U.S. patent application number 12/204961 was filed with the patent office on 2009-03-12 for masked carboxylate neopentyl sulfonyl ester cyclization release prodrugs of acamprosate, compositions thereof, and methods of use.
Invention is credited to Wolf-Nicolas Fischer, Mark A. Gallop, Bernd Jandeleit, Yunxiao Li, Peter A. Virsik, Noa Zerangue.
Application Number | 20090069419 12/204961 |
Document ID | / |
Family ID | 39929810 |
Filed Date | 2009-03-12 |
United States Patent
Application |
20090069419 |
Kind Code |
A1 |
Jandeleit; Bernd ; et
al. |
March 12, 2009 |
MASKED CARBOXYLATE NEOPENTYL SULFONYL ESTER CYCLIZATION RELEASE
PRODRUGS OF ACAMPROSATE, COMPOSITIONS THEREOF, AND METHODS OF
USE
Abstract
Masked carboxylate neopentyl sulfonyl ester prodrugs of
acamprosate, pharmaceutical compositions comprising such prodrugs,
and methods of using such prodrugs and compositions thereof for
treating diseases are disclosed. In particular, acamprosate
prodrugs exhibiting enhanced oral bioavailability and methods of
using acamprosate prodrugs to treat neurodegenerative disorders,
psychotic disorders, mood disorders, anxiety disorders, somatoform
disorders, movement disorders, substance abuse disorders, binge
eating disorder, cortical spreading depression related disorders,
tinnitus, sleeping disorders, multiple sclerosis, and pain are
disclosed.
Inventors: |
Jandeleit; Bernd; (Menlo
Park, CA) ; Li; Yunxiao; (Sunnyvale, CA) ;
Gallop; Mark A.; (Santa Clara, CA) ; Zerangue;
Noa; (Belmont, CA) ; Virsik; Peter A.;
(Portola Valley, CA) ; Fischer; Wolf-Nicolas;
(Sunnyvale, CA) |
Correspondence
Address: |
DORSEY & WHITNEY, LLP;INTELLECTUAL PROPERTY DEPARTMENT
370 SEVENTEENTH STREET, SUITE 4700
DENVER
CO
80202-5647
US
|
Family ID: |
39929810 |
Appl. No.: |
12/204961 |
Filed: |
September 5, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60970924 |
Sep 7, 2007 |
|
|
|
61061059 |
Jun 12, 2008 |
|
|
|
Current U.S.
Class: |
514/517 ;
514/625; 558/49; 564/192 |
Current CPC
Class: |
A61P 25/00 20180101;
A61P 25/02 20180101; A61P 25/28 20180101; A61P 25/22 20180101; A61P
29/00 20180101; C07C 309/15 20130101; A61P 25/18 20180101 |
Class at
Publication: |
514/517 ;
564/192; 558/49; 514/625 |
International
Class: |
A61K 31/255 20060101
A61K031/255; C07C 233/01 20060101 C07C233/01; A61K 31/164 20060101
A61K031/164; A61P 25/28 20060101 A61P025/28; A61P 25/22 20060101
A61P025/22; A61P 25/18 20060101 A61P025/18; C07C 303/02 20060101
C07C303/02 |
Claims
1. A compound of Formula (I): ##STR00033## or a pharmaceutically
acceptable salt thereof, wherein: n is chosen from 0, 1, 2, and 3;
R.sup.1 is chosen from C.sub.1-8 alkyl, substituted C.sub.1-8
alkyl, C.sub.6-10 aryl, substituted C.sub.6-10 aryl, C.sub.3-8
cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.7-18 arylalkyl,
substituted C.sub.7-18 arylalkyl, C.sub.4-16 cycloalkylalkyl,
substituted C.sub.4-16 cycloalkylalkyl, C.sub.1-8 heteroalkyl,
substituted C.sub.1-8 heteroalkyl, C.sub.5-10 heteroaryl,
substituted C.sub.5-10 heteroaryl, C.sub.3-8 heterocycloalkyl,
substituted C.sub.3-8 heterocycloalkyl, C.sub.6-18 heteroarylalkyl,
substituted C.sub.6-18 heteroarylalkyl, C.sub.4-16
heterocycloalkylalkyl, substituted C.sub.4-16
heterocycloalkylalkyl, --C(R.sup.6).sub.2OC(O)R.sup.5,
--C(R.sup.6).sub.2OC(O)OR.sup.5, --(CH).sub.rN(R.sup.6).sub.2, and
(CH.sub.2).sub.rC(O)N(R.sup.6).sub.2, wherein: r is chosen from 1,
2 and 3; each R.sup.5 is independently chosen from C.sub.1-6 alkyl,
substituted C.sub.1-6 alkyl, C.sub.6-8 aryl, substituted C.sub.6-8
aryl, C.sub.3-8 cycloalkyl, substituted C.sub.3-8 cycloalkyl,
C.sub.1-6 heteroalkyl, substituted C.sub.1-6 heteroalkyl, C.sub.5-8
heteroaryl, substituted C.sub.5-8 heteroaryl, C.sub.3-8
heterocycloalkyl, and substituted C.sub.3-8 heterocycloalkyl; and
each R.sup.6 is independently chosen from hydrogen, C.sub.1-8
alkyl, substituted C.sub.1-8 alkyl, C.sub.6-8 aryl, substituted
C.sub.6-8 aryl, C.sub.3-8 cycloalkyl, substituted C.sub.3-8
cycloalkyl, and --COOR.sup.33; wherein R.sup.33 is chosen from
hydrogen and C.sub.1-8 alkyl; R.sup.2 and R.sup.3 are independently
chosen from C.sub.1-4 alkyl, substituted C.sub.1-4 alkyl, C.sub.1-4
alkoxy, substituted C.sub.1-4 alkoxy, --NH.sub.2, --NHC(O)R.sup.34,
--NHR.sup.34 and --N(R.sup.34).sub.2; or R.sup.2 and R.sup.3
together with the carbon to which they are bonded form a ring
chosen from a C.sub.3-8 cycloalkyl, substituted C.sub.3-8
cycloalkyl, C.sub.3-8 heterocycloalkyl, and substituted C.sub.3-8
heterocycloalkyl ring; and each R.sup.4 is independently chosen
from hydrogen, halogen, --OR.sup.7, --CN, --CF.sub.3, .dbd.O,
--NO.sub.2, --COOR.sup.33, C.sub.1-8 alkyl, substituted C.sub.1-8
alkyl, C.sub.6-10 aryl, substituted C.sub.6-10 aryl, C.sub.3-8
cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.7-18 arylalkyl,
substituted C.sub.7-18 arylalkyl, C.sub.4-16 cycloalkylalkyl,
substituted C.sub.4-16 cycloalkylalkyl, C.sub.1-8 heteroalkyl,
substituted C.sub.1-8 heteroalkyl, C.sub.5-10 heteroaryl,
substituted C.sub.5-10 heteroaryl, C.sub.3-8 heterocycloalkyl,
substituted C.sub.3-8 heterocycloalkyl, C.sub.6-18 heteroarylalkyl,
substituted C.sub.6-18 heteroarylalkyl, C.sub.4-16
heterocycloalkylalkyl, substituted C.sub.4-16
heterocycloalkylalkyl, --NH.sub.2, --NHC(O)R.sup.34, --NHR.sup.34,
and --N(R.sup.34).sub.2; wherein: R.sup.7 is chosen from hydrogen,
C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl, C.sub.6-10 aryl,
C.sub.6-10 substituted aryl, C.sub.3-8 cycloalkyl, substituted
C.sub.3-8 cycloalkyl, --C(O)R.sup.8, --C(O)OR.sup.8,
--C(O)N(R.sup.9).sub.2, --C(O)SR.sup.8,
--C(R.sup.9).sub.2OC(O)R.sup.8, --C(R.sup.9).sub.2OC(O)OR.sup.8,
--P(O)(OH).sub.2, and --SO.sub.2OH; wherein: each R.sup.8 is
independently chosen from C.sub.1-6 alkyl, substituted C.sub.1-6
alkyl, C.sub.6-8 aryl, substituted C.sub.6-8 aryl, C.sub.3-8
cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.1-6
heteroalkyl, substituted C.sub.1-6 heteroalkyl, C.sub.5-8
heteroaryl, substituted C.sub.5-8 heteroaryl, C.sub.3-8
heterocycloalkyl, and substituted C.sub.3-8 heterocycloalkyl; and
each R.sup.9 is independently chosen from hydrogen, C.sub.1-8
alkyl, substituted C.sub.1-8 alkyl, C.sub.6-8 aryl, substituted
C.sub.6-8 aryl, C.sub.3-8 cycloalkyl, substituted C.sub.3-8
cycloalkyl, and --COOR.sup.35; wherein R.sup.35 is chosen from
hydrogen and C.sub.1-8 alkyl; R.sup.33 is chosen from hydrogen and
C.sub.1-4 alkyl; each R.sup.34 is independently chosen from
hydrogen, C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl, C.sub.1-8
alkoxy, substituted C.sub.1-8 alkoxy, C.sub.6-10 aryl, substituted
C.sub.6-10 aryl, C.sub.6-10 aryloxy, substituted C.sub.6-10
aryloxy, C.sub.3-8 cycloalkyl, substituted C.sub.3-8 cycloalkyl,
C.sub.3-8 cycloalkoxy, substituted C.sub.3-8 cycloalkoxy,
C.sub.7-18 arylalkyl, substituted C.sub.7-18 arylalkyl, C.sub.4-16
cycloalkylalkyl, substituted C.sub.4-16 cycloalkylalkyl, C.sub.1-8
heteroalkyl, substituted C.sub.1-8 heteroalkyl, C.sub.5-10
heteroaryl, substituted C.sub.5-10 heteroaryl, C.sub.3-8
heterocycloalkyl, substituted C.sub.3-8 heterocycloalkyl,
C.sub.6-18 heteroarylalkyl, substituted C.sub.6-18 heteroarylalkyl,
C.sub.4-16 heterocycloalkylalkyl, and substituted C.sub.4-16
heterocycloalkylalkyl; and with the proviso that when n is 1, and
each of R.sup.2 and R.sup.3 is methyl; then R.sup.4 is not chosen
from --OR.sup.7, --COOR.sup.33, and substituted heteroalkyl.
2. The compound of claim 1, wherein each substituent is
independently chosen from halogen, --OH, --CN, --CF.sub.3,
--OCF.sub.3, .dbd.O, --NO.sub.2, C.sub.1-4 alkoxy, C.sub.1-4 alkyl,
--COOR.sup.30, --NR.sup.31.sub.2, and --CONR.sup.32.sub.2; wherein:
each R.sup.30, R.sup.31, and R.sup.32 is independently chosen from
hydrogen and C.sub.1-4 alkyl.
3. The compound of claim 1, wherein n is chosen from 0, 1, and
2.
4. The compound of claim 1, wherein R.sup.1 is chosen from
C.sub.1-6 alkyl, substituted C.sub.1-6 alkyl, C.sub.3-8 cycloalkyl,
substituted C.sub.3-8 cycloalkyl, C.sub.7-12 arylalkyl, substituted
C.sub.7-12 arylalkyl, C.sub.1-6 heteroalkyl, substituted C.sub.1-6
heteroalkyl, C.sub.3-8 heterocycloalkyl, substituted C.sub.3-8
heterocycloalkyl, C.sub.6-8 heteroarylalkyl, and substituted
C.sub.6-8 heteroarylalkyl.
5. The compound of claim 4, wherein R.sup.1 is chosen from
C.sub.1-6 alkyl, benzyl, substituted benzyl, morpholinyl-N-ethyl,
pyridyl-3-methyl, ethoxycarbonyloxyethyl, and methylbenzyl.
6. The compound of claim 1, wherein R.sup.1 is chosen from
--C(R.sup.6).sub.2OC(O)R.sup.5 and
--C(R.sup.6).sub.2OC(O)OR.sup.5.
7. The compound of claim 6, wherein: R.sup.5 is chosen from methyl,
ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl,
sec-butyl, pentyl, cyclohexyl, phenyl, and 3-pyridyl; and one of
R.sup.6 is hydrogen and the other of R.sup.6 is chosen from
hydrogen, methyl, ethyl, n-propyl, isopropyl, cyclohexyl, and
phenyl; or each of R.sup.6 is methyl.
8. The compound of claim 7, wherein: each of R.sup.2 and R.sup.3 is
methyl; and each R.sup.4 is hydrogen.
9. The compound of claim 1, wherein R.sup.2 and R.sup.3 are
independently chosen from C.sub.1-4 alkyl, substituted C.sub.1-4
alkyl, C.sub.1-4 alkoxy, substituted C.sub.1-4 alkoxy, and
--NH.sub.2.
10. The compound of claim 9, wherein each of R.sup.2 and R.sup.3 is
methyl.
11. The compound of claim 1, wherein each R.sup.4 is hydrogen.
12. The compound of claim 1, wherein the compound is chosen from:
methyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
phenylmethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
phenylmethyl
5-{[3-(acetylamino)propyl]sulfonyloxy}-4,4-dimethylpentanoate;
phenylmethyl
4-{[3-(acetylamino)propyl]sulfonyloxy}-3,3-dimethylbutanoate;
phenylmethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2-({[3-(acetylamino)propyl]sulfony-
loxy}methyl)-2-methylpropanoate;
(4-methoxyphenyl)methyl-3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimeth-
ylpropanoate; ethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
methylethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
2'-morpholinylethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
hydrochloride; pyridinylmethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
hydrochloride; ethoxycarbonyloxyethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
phenylmethyl
2-({[3-(acetylamino)propyl]sulfonyloxy}methyl)-3-hydroxy-2-methylpropanoa-
te; methyl
4-{[3-(acetylamino)propyl]sulfonyloxy}-3,3-dimethylbutanoate;
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoic acid;
5-{[3-(acetylamino)propyl]sulfonyloxy}-4,4-dimethylpentanoic acid;
methylethoxycarbonyloxyethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
4-{[3-(acetylamino)propyl]sulfonyloxy-3,3-dimethylbutanoic acid;
methyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2-[(tert-butoxy)carbonylamino]-2-m-
ethylpropanoate; methyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2-amino-2-methyl propanoate;
ethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-diethoxypropanoate;
benzyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-diethoxypropanoate; and
a pharmaceutically acceptable salt of any of the foregoing.
13. The compound of claim 1, wherein the compound is chosen from:
phenylmethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
ethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate; and
a pharmaceutically acceptable salt of any of the foregoing.
14. A compound of Formula (II): ##STR00034## or a pharmaceutically
acceptable salt thereof; wherein: q is chosen from 0, 1, 2, and 3;
R.sup.22 and R.sup.23 are independently chosen from C.sub.1-4
alkyl, substituted C.sub.1-4 alkyl, C.sub.1-4 alkoxy, substituted
C.sub.1-4 alkoxy, --NH.sub.2, --NHC(O)R.sup.34, --NHR.sup.34, and
--NR.sup.34.sub.2; or R.sup.22 and R.sup.23 together with the
carbon to which they are bonded form a ring chosen from a C.sub.3-8
cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.3-8
heterocycloalkyl, and substituted C.sub.3-8 heterocycloalkyl ring;
and each R.sup.24 is independently chosen from hydrogen, halogen,
--OR.sup.7, --CN, --CF.sub.3, .dbd.O, --NO.sub.2, --COOR.sup.33,
C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl, C.sub.6-10 aryl,
substituted C.sub.6-10 aryl, C.sub.3-8 cycloalkyl, substituted
C.sub.3-8 cycloalkyl, C.sub.7-18 arylalkyl, substituted C.sub.7-18
arylalkyl, C.sub.4-16 cycloalkylalkyl, substituted C.sub.4-16
cycloalkylalkyl, C.sub.1-8 heteroalkyl, substituted C.sub.1-8
heteroalkyl, C.sub.5-10 heteroaryl, substituted C.sub.5-10
heteroaryl, C.sub.3-8 heterocycloalkyl, substituted C.sub.3-8
heterocycloalkyl, C.sub.6-18 heteroarylalkyl, substituted
C.sub.6-18 heteroarylalkyl, C.sub.4-16 heterocycloalkylalkyl,
substituted C.sub.4-16 heterocycloalkylalkyl, --NH.sub.2,
--NHC(O)R.sup.34, --NHR.sup.34, and --N(R.sup.34).sub.2; wherein:
R.sup.7 is chosen from hydrogen, C.sub.1-8 alkyl, substituted
C.sub.1-8 alkyl, C.sub.6-10 aryl, substituted C.sub.6-10 aryl,
C.sub.3-8 cycloalkyl, substituted C.sub.3-8 cycloalkyl,
--C(O)R.sup.8, --C(O)OR.sup.8, --C(O)N(R.sup.9).sub.2,
--C(O)SR.sup.8, --C(R.sup.9).sub.2OC(O)R.sup.8, and
--C(R.sup.9).sub.2OC(O)OR.sup.8; wherein: each R.sup.8 is
independently chosen from C.sub.1-6 alkyl, substituted C.sub.1-6
alkyl, C.sub.6-8 aryl, substituted C.sub.6-8 aryl, C.sub.3-8
cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.1-6
heteroalkyl, substituted C.sub.1-6 heteroalkyl, C.sub.5-8
heteroaryl, substituted C.sub.5-8 heteroaryl, C.sub.3-8
heterocycloalkyl, and substituted C.sub.3-8 heterocycloalkyl; each
R.sup.9 is independently chosen from hydrogen, C.sub.1-8 alkyl,
substituted C.sub.1-8 alkyl, C.sub.6-8 aryl, substituted C.sub.6-8
aryl, C.sub.3-8 cycloalkyl, substituted C.sub.3-8 cycloalkyl, and
--COOR.sup.35; wherein R.sup.35 is chosen from hydrogen and
C.sub.1-8 alkyl; R.sup.33 is chosen from hydrogen and C.sub.1-4
alkyl; each R.sup.34 is independently chosen from hydrogen,
C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl, C.sub.1-8 alkoxy,
substituted C.sub.1-8 alkoxy, C.sub.6-10 aryl, substituted
C.sub.6-10 aryl, C.sub.6-10 aryloxy, substituted C.sub.6-10
aryloxy, C.sub.3-8 cycloalkyl, substituted C.sub.3-8 cycloalkyl,
C.sub.3-8 cycloalkoxy, substituted C.sub.3-8 cycloalkoxy,
C.sub.7-18 arylalkyl, substituted C.sub.7-18 arylalkyl, C.sub.4-16
cycloalkylalkyl, substituted C.sub.4-16 cycloalkylalkyl, C.sub.1-8
heteroalkyl, substituted C.sub.1-8 heteroalkyl, C.sub.5-10
heteroaryl, substituted C.sub.5-10 heteroaryl, C.sub.3-8
heterocycloalkyl, substituted C.sub.3-8 heterocycloalkyl,
C.sub.6-18 heteroarylalkyl, substituted C.sub.6-18 heteroarylalkyl,
C.sub.4-16 heterocycloalkylalkyl, and substituted C.sub.4-16
heterocycloalkylalkyl; and with the proviso that when n is 1, and
each of R.sup.22 and R.sup.23 is methyl; then R.sup.24 is not
chosen from OR.sup.7, --COOR.sup.33, and substituted
heteroalkyl.
15. The compound of claim 14, wherein each substituent is
independently chosen from halogen, --OH, --CN, --CF.sub.3,
--OCF.sub.3, .dbd.O, --NO.sub.2, C.sub.1-4 alkoxy, C.sub.1-4 alkyl,
--COOR.sup.30, --NR.sup.31.sub.2, and --CONR.sup.32.sub.2; wherein:
each R.sup.30, R.sup.31, and R.sup.32 is independently chosen from
hydrogen and C.sub.1-4 alkyl.
16. The compound of claim 14, wherein q is chosen from 0, 1, and
2.
17. The compound of claim 14, wherein R.sup.22 and R.sup.23 are
independently chosen from C.sub.1-4 alkyl and C.sub.1-4 alkoxy.
18. The compound of claim 17, wherein each of R.sup.22 and R.sup.23
is methyl.
19. The compound of any one of claims 14 and 18, wherein each
R.sup.24 is hydrogen.
20. The compound of claim 14, wherein the compound is chosen from:
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoic acid;
4-{[3-(acetylamino)propyl]sulfonyloxy-3,3-dimethylbutanoic acid;
5-{[3-(acetylamino)propyl]sulfonyloxy}-4,4-dimethylpentanoic acid;
and a pharmaceutically acceptable salt of any of the foregoing.
21. A pharmaceutical composition comprising a compound of claim 1
and at least one pharmaceutically acceptable vehicle.
22. The pharmaceutical composition of claim 21, comprising an
amount of the compound effective for the treatment of a disease
chosen from a neurodegenerative disorder, a psychotic disorder, a
mood disorder, an anxiety disorder, a somatoform disorder, a
movement disorder, a substance abuse disorder, binge eating
disorder, a cortical spreading depression related disorder, a
sleeping disorder, tinnitus, multiple sclerosis, and pain.
23. The pharmaceutical composition of claim 21, wherein the
pharmaceutical composition is a sustained release oral dosage
formulation.
24. A method of treating a disease in a patient comprising
administering to a patient in need of such treatment the
pharmaceutical composition of claim 21, wherein the disease is
chosen from a neurodegenerative disorder, a psychotic disorder, a
mood disorder, an anxiety disorder, a somatoform disorder, movement
disorder, a substance abuse disorder, binge eating disorder, a
cortical spreading depression related disorder, a sleeping
disorder, tinnitus, multiple sclerosis, and pain.
25. A method of treating a disease in a patient comprising
administering to a patient in need of such treatment the compound
of claim 1, wherein the disease is chosen from a neurodegenerative
disorder, a psychotic disorder, a mood disorder, an anxiety
disorder, a somatoform disorder, movement disorder, a substance
abuse disorder, binge eating disorder, a cortical spreading
depression related disorder, a sleeping disorder, tinnitus,
multiple sclerosis, and pain.
Description
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119(e) of U.S. Provisional Application Ser. Nos. 60/970,924
filed Sep. 7, 2007, and 61/061,059 filed Jun. 12, 2008, each of
which is incorporated by reference in its entirety.
FIELD
[0002] Disclosed herein are masked carboxylate neopentyl sulfonyl
ester prodrugs of acamprosate that exhibit enhanced oral
bioavailability, pharmaceutical compositions comprising such
prodrugs, and methods of using such prodrugs and compositions
thereof for treating diseases. In particular, acamprosate prodrugs
exhibiting enhanced oral bioavailability and methods of using
acamprosate prodrugs to treat neurodegenerative disorders,
psychotic disorders, mood disorders, anxiety disorders, somatoform
disorders, movement disorders, substance abuse disorders, binge
eating disorder, cortical spreading depression related disorders,
sleeping disorders, tinnitus, multiple sclerosis, and pain.
BACKGROUND
[0003] Prodrugs are derivatized forms of drugs that following
administration are converted or metabolized to an active form of
the drug in vivo. Prodrugs are used to modify one or more aspects
of the pharmacokinetics of a drug in a manner that enhances the
therapeutic efficacy of a drug. For example, prodrugs are often
used to enhance the oral bioavailability of a drug. To be
therapeutically effective, drugs exhibiting poor oral
bioavailability may require frequent dosing, large administered
doses, or may need to be administered by other than oral routes,
such as intravenously. In particular, many drugs with sulfonic acid
groups exhibit poor oral bioavailability.
[0004] Intramolecular cyclization prodrug strategies have been used
to modify the pharmacokinetics of drugs (Bundgaard in "A Textbook
of Drug Design and Development," Krogsgaard-Larsen and Bundgaard
Eds., Harwood Academic, Philadelphia, 1991, pp. 113-192; Bungaard
and Nielsen, U.S. Pat. No. 5,073,641; Santos et al., Bionorganic
& Medicinal Chemistry Letters, 2005, 15, 1595-1598; Papot et
al., Curr Med Chem--Anti-Cancer Agents, 2002, 2, 155-185; and Shan
et al., J Pharm Sciences 1997, 86(7), 765-767). Intramolecular
cyclization release prodrug strategies have been applied to drugs
containing sulfonic acid functional groups. Prodrugs comprising a
substituted neopentyl sulfonate ester derivative in which the
neopentyl group is removed in vivo by unmasking a nucleophilic
heteroatom bonded to a substituted neopentyl moiety followed by
intramolecular cyclization to generate the parent drug in the
sulfonic acid or sulfonic acid salt form have been described
(Roberts and Patch, U.S. Pat. No. 5,596,095; and Roberts et al.,
Tetrahedron Lett 1997, 38(3), 355-358). In such prodrugs the
nucleophilic heteroatom can be nitrogen or oxygen and the nitrogen
or oxygen nucleophile can be masked with any amine or alcohol
protecting group, respectively, capable of being deprotected in
vivo. Roberts and Patch also disclose that the masked nucleophilic
group can be a carboxylic ester, e.g., --OCOR where R can be aryl,
substituted aryl, heteroaryl, C.sub.1-8 alkyl, arylalkyl, or
heteroarylalkyl. However, Roberts and Patch do not provide
biological or pharmacological data to indicate which if any of the
substituted neopentyl sulfonate esters release the prodrug in vivo
and would therefore be useful for enhancing the oral
bioavailability of the corresponding drug.
[0005] 3-(Acetylamino)propylsulfonic acid (also referred to as
N-acetylhomotaurine), acamprosate,
##STR00001##
is a derivative of homotaurine, a naturally occurring structural
analog of .gamma.-aminobutyric acid (GABA) that appears to affect
multiple receptors in the central nervous system (CNS). As an
antiglutamatergic agent, acamprosate is believed to exert a
neuropharmacological effect as an antagonist of
N-methyl-D-aspartate (NMDA) receptors. The mechanism of action is
believed to include blocking of the Ca.sup.2+ channel to slow
Ca.sup.2+ influx and reduce the expression of c-fos, leading to
changes in messenger RNA transcription and the concomitant
modification to the subunit composition of NMDA receptors in
selected brain regions (Zornoza et al., CNS Drug Reviews, 2003,
9(4), 359-374; and Rammes et al., Neuropharmacology 2001, 40,
749-760). In addition, acamprosate may block GABA.sub.B receptors
(Daost, et al., Pharmacol Biochem Behav. 1992, 41, 669-74; and
Johnson et al., Psychopharmacology 2000, 149, 327-344). Similar
mechanisms are believed to be associated with the activity of other
glutamate modulators such as riluzole, N-acetylcysteine,
.beta.-lactams, amantadine, lamictal, memantine, neramexane,
remacemide, ifenprodil, and dextromethorphan.
[0006] Other diseases or disorders known to be associated with
modulation of NMDA activity and for which modulators of NMDA
receptor activity are clinically useful include psychotic disorders
such as schizophrenia and schizoaffective disorder; mood disorders
such as anxiety disorders including posttraumatic stress disorder
and obsessive-compulsive disorder, depression, mania, bipolar
disorder; and somatoform disorders such as somatization disorder,
conversion disorder, hypochondriasis, and body dysmorphic disorder;
movement disorders such as Tourette's syndrome, focal dystonia,
Huntington's disease, Parkinson's disease, Syndeham's chorea,
systemic lupus erythematosus, drug-induced movement disorders,
tardive dyskinesia, blepharospasm, tic disorder, and spasticity;
substance abuse disorders such as alcohol abuse disorders, narcotic
abuse disorders, and nicotine abuse disorders; cortical spreading
depression related disorders such as migraine, cerebral damage,
epilepsy, and cardiovascular; sleeping disorders such as sleep
apnea; multiple sclerosis; and neurodegenerative disorders such as
Parkinson's disease, Huntington's disease, Alzheimer's disease, and
amyotrophic lateral sclerosis. Recently, acamprosate has been found
to be effective in treating tinnitus, or noise originating in the
ear, a common disorder (de Azevedo et al., 109.sup.th Meeting and
OTO EXPO of the Am. Acad. Otolaryngology--Head and Neck Foundation,
Los Angeles, Calif., Sep. 25-28, 2005; Azevedo et al, Rev. Bras.
Otorrinolaringol. Engl. Ed., 2005, 71, 618-623; and Azevedo et al.,
WO 2007/082561 A2). Acamprosate analogs (Berthelon et al., U.S.
Pat. No. 6,265,437) and salt forms of acamprosate analogs (Durlach,
U.S. Pat. No. 4,355,043) are also reported to have therapeutic
potential.
[0007] There is also evidence that acamprosate may interact with
excitatory glutamatergic neurotransmission in general and as an
antagonist of the metabotropic glutamate receptor subtype 5
(mGluR5) in particular (De Witte et al., CNS Drugs 2005, 19(6),
517-37). The glutamatergic mechanism of action of acamprosate may
explain the effects of acamprosate on alcohol dependence and
suggests other activities such as in neuroprotection. Dysregulation
of the mGluR5 receptor has been implicated in a number of diseases
and mGluR5 antagonists have been shown to be effective in treating
depression, pain, anxiety disorders, alcohol abuse disorders, drug
abuse disorders, nicotine abuse disorders, neurodegenerative
disorders such as Parkinson's disease, diabetes, schizophrenia, and
gastrointestinal reflux disease.
[0008] Acamprosate is a polar molecule that lacks the requisite
physicochemical characteristics for effective passive permeability
across cellular membranes. Intestinal absorption of acamprosate is
mainly by passive diffusion and to a lesser extent by an active
transport mechanism such as via an amino acid transporter
(Mas-Serrano et al., Alcohol 2000, 4(3); and 324-330; Saivin et
al., Clin Pharmacokinet 1998, 35, 331-345). As a consequence, the
oral bioavailability of acamprosate in humans is only about 11%.
The mean elimination half-life of acamprosate following intravenous
infusion (15 min) is 3.2.+-.0.2 h. Efforts to enhance the
gastrointestinal absorption and oral bioavailability of acamprosate
include co-administrating the drug with polyglycolysed glycerides
(Saslawski et al., U.S. Pat. No. 6,514,524). Acamprosate prodrugs
exhibiting enhanced absorption from the lower gastrointestinal
tract have the potential to increase the oral bioavailability of
the drug and to facilitate administration of acamprosate using
sustained release oral dosage forms.
SUMMARY
[0009] Thus, there is a need for new prodrugs of acamprosate with
demonstrated enhanced oral bioavailability. In particular, masked
carboxylate neopentylsulfonate ester prodrugs of acamprosate that
exhibit enhanced absorption throughout the gastrointestinal tract
and especially in the large intestine/colon and hence that are
suitable for sustained release oral formulations, can enhance the
convenience (by reducing the dose and dosing frequency), efficacy,
and side effect profile of acamprosate.
[0010] In a first aspect, compounds of Formula (I) are
provided:
##STR00002## [0011] or a pharmaceutically acceptable salt thereof;
wherein: [0012] n is chosen from 0, 1, 2, and 3; [0013] R.sup.1 is
chosen from C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl,
C.sub.6-10 aryl, substituted C.sub.6-10 aryl, C.sub.3-8 cycloalkyl,
substituted C.sub.3-8 cycloalkyl, C.sub.7-18 arylalkyl, substituted
C.sub.7-18 arylalkyl, C.sub.4-16 cycloalkylalkyl, substituted
C.sub.4-16 cycloalkylalkyl, C.sub.1-8 heteroalkyl, substituted
C.sub.1-8 heteroalkyl, C.sub.5-10 heteroaryl, substituted
C.sub.5-10 heteroaryl, C.sub.3-8 heterocycloalkyl, substituted
C.sub.3-8 heterocycloalkyl, C.sub.6-18 heteroarylalkyl, substituted
C.sub.6-18 heteroarylalkyl, C.sub.4-16 heterocycloalkylalkyl,
substituted C.sub.4-16 heterocycloalkylalkyl,
--C(R.sup.6).sub.2OC(O)R.sup.5, --C(R.sup.6).sub.2OC(O)OR.sup.5,
(CH.sub.2).sub.rN(R.sup.6).sub.2, and
--(CH.sub.2).sub.rC(O)N(R.sup.6).sub.2, wherein: [0014] r is chosen
from 1, 2 and 3; [0015] each R.sup.5 is independently chosen from
C.sub.1-6 alkyl, substituted C.sub.1-6 alkyl, C.sub.6-8 aryl,
substituted C.sub.6-8 aryl, C.sub.3-8 cycloalkyl, substituted
C.sub.3-8 cycloalkyl, C.sub.1-6 heteroalkyl, substituted C.sub.1-6
heteroalkyl, C.sub.5-8 heteroaryl, substituted C.sub.5-8
heteroaryl, C.sub.3-8 heterocycloalkyl, and substituted C.sub.3-8
heterocycloalkyl; and [0016] each R.sup.6 is independently chosen
from hydrogen, C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl,
C.sub.6-8 aryl, substituted C.sub.6-8 aryl, C.sub.3-8 cycloalkyl,
substituted C.sub.3-8 cycloalkyl, and --COOR.sup.33; wherein
R.sup.33 is chosen from hydrogen and C.sub.1-8 alkyl; [0017]
R.sup.2 and R.sup.3 are independently chosen from C.sub.1-4 alkyl,
substituted C.sub.1-4 alkyl, C.sub.1-4 alkoxy, substituted
C.sub.1-4 alkoxy, --NH.sub.2, --NHC(O)R.sup.34, --NHR.sup.34, and
--N(R.sup.34).sub.2; or R.sup.2 and R.sup.3 together with the
carbon to which they are bonded form a ring chosen from a C.sub.3-8
cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.3-8
heterocycloalkyl, and substituted C.sub.3-8 heterocycloalkyl ring;
and [0018] each R.sup.4 is independently chosen from hydrogen,
halogen, --OR.sup.7, --CN, --CF.sub.3, .dbd.O, --NO.sub.2,
--COOR.sup.33, C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl,
C.sub.6-10 aryl, substituted C.sub.6-10 aryl, C.sub.3-8 cycloalkyl,
substituted C.sub.3-8 cycloalkyl, C.sub.7-18 arylalkyl, substituted
C.sub.7-18 arylalkyl, C.sub.4-16 cycloalkylalkyl, substituted
C.sub.4-16 cycloalkylalkyl, C.sub.1-8 heteroalkyl, substituted
C.sub.1-8 heteroalkyl, C.sub.5-10 heteroaryl, substituted
C.sub.5-10 heteroaryl, C.sub.3-8 heterocycloalkyl, substituted
C.sub.3-8 heterocycloalkyl, C.sub.6-18 heteroarylalkyl, substituted
C.sub.6-18 heteroarylalkyl, C.sub.4-16 heterocycloalkylalkyl,
substituted C.sub.4-16 heterocycloalkylalkyl, --NH.sub.2,
--NHC(O)R.sup.34, --NHR.sup.34, and --NR.sup.34.sub.2; wherein
[0019] R.sup.7 is chosen from hydrogen, C.sub.1-8 alkyl,
substituted C.sub.1-8 alkyl, C.sub.6-10 aryl, C.sub.6-10
substituted aryl, C.sub.3-8 cycloalkyl, substituted C.sub.3-8
cycloalkyl, --C(O)R.sup.8, --C(O)OR.sup.8, --C(O)N(R.sup.9).sub.2,
--C(O)SR.sup.8, --C(R.sup.9).sub.2OC(O)R.sup.8,
--C(R.sup.9).sub.2OC(O)OR.sup.8, --P(O)(OH).sub.2, and
--SO.sub.2OH; wherein: [0020] each R.sup.8 is independently chosen
from C.sub.1-6 alkyl, substituted C.sub.1-6 alkyl, C.sub.6-8 aryl,
substituted C.sub.6-8 aryl, C.sub.3-8 cycloalkyl, substituted
C.sub.3-8 cycloalkyl, C.sub.1-6 heteroalkyl, substituted C.sub.1-6
heteroalkyl, C.sub.5-8 heteroaryl, substituted C.sub.5-8
heteroaryl, C.sub.3-8 heterocycloalkyl, and substituted C.sub.3-8
heterocycloalkyl; and [0021] each R.sup.9 is independently chosen
from hydrogen, C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl,
C.sub.6-8 aryl, substituted C.sub.6-8 aryl, C.sub.3-8 cycloalkyl,
substituted C.sub.3-8 cycloalkyl, and --COOR.sup.35; wherein
R.sup.35 is chosen from hydrogen and C.sub.1-8 alkyl; [0022]
R.sup.33 is chosen from hydrogen and C.sub.1-4 alkyl; [0023] each
R.sup.34 is independently chosen from hydrogen, C.sub.1-8 alkyl,
substituted C.sub.1-8 alkyl, C.sub.1-8 alkoxy, substituted
C.sub.1-8 alkoxy, C.sub.6-10 aryl, substituted C.sub.6-10 aryl,
C.sub.6-10 aryloxy, substituted C.sub.6-10 aryloxy, C.sub.3-8
cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.3-8
cycloalkoxy, substituted C.sub.3-8 cycloalkoxy, C.sub.7-18
arylalkyl, substituted C.sub.7-18 arylalkyl, C.sub.4-16
cycloalkylalkyl, substituted C.sub.4-16 cycloalkylalkyl, C.sub.1-8
heteroalkyl, substituted C.sub.1-8 heteroalkyl, C.sub.5-10
heteroaryl, substituted C.sub.5-10 heteroaryl, C.sub.3-8
heterocycloalkyl, substituted C.sub.3-8 heterocycloalkyl,
C.sub.6-18 heteroarylalkyl, substituted C.sub.6-18 heteroarylalkyl,
C.sub.4-16 heterocycloalkylalkyl, and substituted C.sub.4-16
heterocycloalkylalkyl; and [0024] with the proviso that when n is
1, and each of R.sup.2 and R.sup.3 is methyl; then R.sup.4 is not
chosen from --OR.sup.7, --COOR.sup.33, and substituted
heteroalkyl.
[0025] In a second aspect, compounds of Formula (II) are
provided.
##STR00003## [0026] or a pharmaceutically acceptable salt thereof;
wherein: [0027] q is chosen from 0, 1, 2, and 3; [0028] R.sup.22
and R.sup.23 are independently chosen from C.sub.1-4 alkyl,
substituted C.sub.1-4 alkyl, C.sub.1-4 alkoxy, and substituted
C.sub.1-4 alkoxy; or R.sup.22 and R.sup.23 together with the carbon
to which they are bonded form a ring chosen from a C.sub.3-8
cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.3-8
heterocycloalkyl, and substituted C.sub.3-8 heterocycloalkyl ring;
and [0029] each R.sup.24 is independently chosen from hydrogen,
halogen, --OR.sup.7, --CN, --CF.sub.3, .dbd.O, --NO.sub.2,
--COOR.sup.33, C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl,
C.sub.6-10 aryl, substituted C.sub.6-10 aryl, C.sub.3-8 cycloalkyl,
substituted C.sub.3-8 cycloalkyl, C.sub.7-18 arylalkyl, substituted
C.sub.7-18 arylalkyl, C.sub.4-16 cycloalkylalkyl, substituted
C.sub.4-16 cycloalkylalkyl, C.sub.1-8 heteroalkyl, substituted
C.sub.1-8 heteroalkyl, C.sub.5-10 heteroaryl, substituted
C.sub.5-10 heteroaryl, C.sub.3-8 heterocycloalkyl, substituted
C.sub.3-8 heterocycloalkyl, C.sub.6-18 heteroarylalkyl, substituted
C.sub.6-18 heteroarylalkyl, C.sub.4-16 heterocycloalkylalkyl,
substituted C.sub.4-16 heterocycloalkylalkyl,
--NH.sub.2,--NHC(O)R.sup.34, and --N(R.sup.34).sub.2; wherein:
[0030] R.sup.7 is chosen from hydrogen, C.sub.1-8 alkyl,
substituted C.sub.1-8 alkyl, C.sub.6-10 aryl, substituted
C.sub.6-10 aryl, C.sub.3-8 cycloalkyl, substituted C.sub.3-8
cycloalkyl, --C(O)R.sup.8, --C(O)OR.sup.8, --C(O)N(R.sub.9).sub.2,
--C(O)SR.sup.8, --C(R.sup.9).sub.2OC(O)R.sup.8, and
--C(R.sup.9).sub.2OC(O)OR.sup.8; wherein: [0031] each R.sup.8 is
independently chosen from C.sub.1-6 alkyl, substituted C.sub.1-6
alkyl, C.sub.6-8 aryl, substituted C.sub.6-8 aryl, C.sub.3-8
cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.1-6
heteroalkyl, substituted C.sub.1-6 heteroalkyl, C.sub.5-8
heteroaryl, substituted C.sub.5-8 heteroaryl, C.sub.3-8
heterocycloalkyl, and substituted C.sub.3-8 heterocycloalkyl;
[0032] each R.sup.9 is independently chosen from hydrogen,
C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl, C.sub.6-8 aryl,
substituted C.sub.6-8 aryl, C.sub.3-8 cycloalkyl, substituted
C.sub.3-8 cycloalkyl, and --COOR.sup.35; wherein R.sup.35 is chosen
from hydrogen and C.sub.1-8 alkyl; [0033] R.sup.33 is chosen from
hydrogen and C.sub.1-4 alkyl; [0034] each R.sup.34 is independently
chosen from hydrogen, C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl,
C.sub.1-8 alkoxy, substituted C.sub.1-8 alkoxy, C.sub.6-10 aryl,
substituted C.sub.6-10 aryl, C.sub.6-10 aryloxy, substituted
C.sub.6-10 aryloxy, C.sub.3-8 cycloalkyl, substituted C.sub.3-8
cycloalkyl, C.sub.3-8 cycloalkoxy, substituted C.sub.3-8
cycloalkoxy, C.sub.7-18 arylalkyl, substituted C.sub.7-18
arylalkyl, C.sub.4-16 cycloalkylalkyl, substituted C.sub.4-16
cycloalkylalkyl, C.sub.1-8 heteroalkyl, substituted C.sub.1-8
heteroalkyl, C.sub.5-10 heteroaryl, substituted C.sub.5-10
heteroaryl, C.sub.3-8 heterocycloalkyl, substituted C.sub.3-8
heterocycloalkyl, C.sub.6-18 heteroarylalkyl, substituted
C.sub.6-18 heteroarylalkyl, C.sub.4-16 heterocycloalkylalkyl, and
substituted C.sub.4-16 heterocycloalkylalkyl; and [0035] with the
proviso that when n is 1, and each of R.sup.22 and R.sup.23 is
methyl; then R.sup.24 is not --OH.
[0036] In a third aspect, pharmaceutical compositions are provided
comprising at least one pharmaceutically acceptable excipient and
at least one compound of Formula (I) or a pharmaceutically
acceptable salt thereof.
[0037] In a fourth aspect, methods of treating a disease in a
patient are provided comprising administering to a patient in need
of such treatment a therapeutically effective amount of a compound
of Formula (I) or a pharmaceutically acceptable salt thereof. In
certain embodiments, the disease is chosen from a neurodegenerative
disorder, a psychotic disorder, a mood disorder, an anxiety
disorder, a somatoform disorder, a movement disorder, a substance
abuse disorder, binge eating disorder, a cortical spreading
depression related disorder, tinnitus, a sleeping disorder,
multiple sclerosis, and pain.
DETAILED DESCRIPTION
Definitions
[0038] A dash ("--") that is not between two letters or symbols is
used to indicate a point of bonding to a moiety or substituent. For
example, --CONH.sub.2 is attached through the carbon atom.
[0039] "Alkyl" by itself or as part of another substituent refers
to a saturated or unsaturated, branched, or straight-chain,
monovalent hydrocarbon radical derived by the removal of one
hydrogen atom from a single carbon atom of a parent alkane, alkene,
or alkyne. Examples of alkyl groups include, but are not limited
to, methyl; ethyls such as ethanyl, ethenyl, and ethynyl; propyls
such as propan-1-yl, propan-2-yl, prop-1-en-1-yl, prop-1-en-2-yl,
prop-2-en-1-yl (allyl), prop-1-yn-1-yl, prop-2-yn-1-yl, etc.;
butyls such as butan-1-yl, butan-2-yl, 2-methyl-propan-1-yl,
2-methyl-propan-2-yl, but-1-en-1-yl, but-1-en-2-yl,
2-methyl-prop-1-en-1-yl, but-2-en-1-yl, but-2-en-2-yl,
buta-1,3-dien-1-yl, buta-1,3-dien-2-yl, but-1-yn-1-yl,
but-1-yn-3-yl, but-3-yn-1-yl, etc.; and the like.
[0040] The term "alkyl" is specifically intended to include groups
having any degree or level of saturation, i.e., groups having
exclusively single carbon-carbon bonds, groups having one or more
double carbon-carbon bonds, groups having one or more triple
carbon-carbon bonds, and groups having mixtures of single, double,
and triple carbon-carbon bonds. Where a specific level of
saturation is intended, the terms "alkanyl," "alkenyl," and
"alkynyl" are used. In certain embodiments, an alkyl group can have
from 1 to 20 carbon atoms, in certain embodiments, from 1 to 10
carbon atoms, in certain embodiments from 1 to 8 carbon atoms, in
certain embodiments, from 1 to 6 carbon atoms, in certain
embodiments from 1 to 4 carbon atoms, and in certain embodiments,
from 1 to 3 carbon atoms.
[0041] "Alkoxy" by itself or as part of another substituent refers
to a radical --OR.sup.31 where R.sup.31 is chosen from alkyl,
heteroalkyl, cycloalkyl, heterocycloalkyl, cycloalkylalkyl,
heterocycloalkylalkyl, aryl, heteroaryl, arylalkyl, and
heteroarylalkyl, as defined herein. Examples of alkoxy groups
include, but are not limited to, methoxy, ethoxy, propoxy, butoxy,
cyclohexyloxy, and the like. In certain embodiments, an alkoxy
group is C.sub.1-18 alkoxy, in certain embodiments, C.sub.1-12
alkoxy, in certain embodiments, C.sub.1-8 alkoxy, in certain
embodiments, C.sub.1-6 alkoxy, in certain embodiments, C.sub.1-4
alkoxy, and in certain embodiments, C.sub.1-3 alkoxy.
[0042] "Aryl" by itself or as part of another substituent refers to
a monovalent aromatic hydrocarbon radical derived by the removal of
one hydrogen atom from a single carbon atom of a parent aromatic
ring system. Aryl encompasses 5- and 6-membered carbocyclic
aromatic rings, for example, benzene; bicyclic ring systems wherein
at least one ring is carbocyclic and aromatic, for example,
naphthalene, indane, and tetralin; and tricyclic ring systems
wherein at least one ring is carbocyclic and aromatic, for example,
fluorene. Aryl encompasses multiple ring systems having at least
one carbocyclic aromatic ring fused to at least one carbocyclic
aromatic ring, cycloalkyl ring, or heterocycloalkyl ring. For
example, aryl includes 5- and 6-membered carbocyclic aromatic rings
fused to a 5- to 7-membered heterocycloalkyl ring containing one or
more heteroatoms chosen from N, O, and S. For such fused, bicyclic
ring systems wherein only one of the rings is a carbocyclic
aromatic ring, the point of attachment may be at the carbocyclic
aromatic ring or the heterocycloalkyl ring. Examples of aryl groups
include, but are not limited to, groups derived from aceanthrylene,
acenaphthylene, acephenanthrylene, anthracene, azulene, benzene,
chrysene, coronene, fluoranthene, fluorene, hexacene, hexaphene,
hexalene, as-indacene, s-indacene, indane, indene, naphthalene,
octacene, octaphene, octalene, ovalene, penta-2,4-diene, pentacene,
pentalene, pentaphene, perylene, phenalene, phenanthrene, picene,
pleiadene, pyrene, pyranthrene, rubicene, triphenylene,
trinaphthalene, and the like. In certain embodiments, an aryl group
can have from 6 to 20 carbon atoms (C.sub.6-20), from 6 to 12
carbon atoms (C.sub.6-12), and in certain embodiments, from 6 to 10
carbon atoms (C.sub.6-10).
[0043] "Arylalkyl" by itself or as part of another substituent
refers to an acyclic alkyl radical in which one of the hydrogen
atoms bonded to a carbon atom, typically a terminal or sp.sup.3
carbon atom, is replaced with an aryl group. Examples of arylalkyl
groups include, but are not limited to, benzyl, 2-phenylethan-1-yl,
2-phenyl ethen-1-yl, naphthylmethyl, 2-naphthylethan-1-yl,
2-naphthylethen-1-yl, naphthobenzyl, 2-naphthophenylethan-1-yl and
the like. Where specific alkyl moieties are intended, the
nomenclature arylalkanyl, arylalkenyl, or arylalkynyl is used. In
certain embodiments, an arylalkyl group is C.sub.7-30 arylalkyl,
e.g., the alkanyl, alkenyl or alkynyl moiety of the arylalkyl group
is C.sub.1-10 and the aryl moiety is C.sub.7-20, in certain
embodiments, an arylalkyl group is C.sub.6-18 arylalkyl, e.g., the
alkanyl, alkenyl or alkynyl moiety of the arylalkyl group is
C.sub.1-8 and the aryl moiety is C.sub.6-10.
[0044] "AUC" is the area under a curve representing the
concentration of a compound or metabolite thereof in a biological
fluid in a patient as a function of time following administration
of the compound to the patient. In certain embodiments provided by
the present disclosure, the compound is a prodrug of Formula (I)
the drug is acamprosate. Examples of biological fluids include
plasma, blood, and cerebrospinal fluid. The AUC may be determined
by measuring the concentration of a compound or metabolite thereof
in a biological fluid such as the plasma or blood using methods
such as liquid chromatography-tandem mass spectrometry (LC/MS/MS),
at various time intervals, and calculating the area under the
plasma concentration-versus-time curve. Suitable methods for
calculating the AUC from a drug concentration-versus-time curve are
well known in the art. As relevant to the present disclosure, an
AUC for acamprosate or metabolite thereof may be determined by
measuring over time the concentration of acamprosate or metabolite
thereof in the plasma, blood, or other biological fluid or tissue
of a patient following administration of a corresponding prodrug of
Formula (I) to the patient.
[0045] "Bioavailability" refers to the rate and amount of a drug
that reaches the systemic circulation of a patient following
administration of the drug or prodrug thereof to the patient and
can be determined by evaluating, for example, the plasma or blood
concentration-versus-time profile for a drug. Parameters useful in
characterizing a plasma or blood concentration-versus-time curve
include the area under the curve (AUC), the time to maximum
concentration (T.sub.max), and the maximum drug concentration
(C.sub.max), where C.sub.max is the maximum concentration of a drug
in the plasma or blood of a patient following administration of a
dose of the drug or form of drug to the patient, and T.sub.max is
the time to the maximum concentration (C.sub.max) of a drug in the
plasma or blood of a patient following administration of a dose of
the drug or form of drug to the patient.
[0046] "C.sub.max" is the maximum concentration of a drug in the
plasma or blood of a patient following administration of a dose of
the drug or prodrug to the patient.
[0047] "T.sub.max" is the time to the maximum (peak) concentration
(C.sub.max) of a drug in the plasma or blood of a patient following
administration of a dose of the drug or prodrug to the patient.
[0048] "Compounds" of Formula (I)-(II) disclosed herein include any
specific compounds within these formulae. Compounds may be
identified either by their chemical structure and/or chemical name.
When the chemical structure and chemical name conflict, the
chemical structure is determinative of the identity of the
compound. The compounds described herein may comprise one or more
chiral centers and/or double bonds and therefore may exist as
stereoisomers such as double-bond isomers (i.e., geometric
isomers), enantiomers, or diastereomers. Accordingly, any chemical
structures within the scope of the specification depicted, in whole
or in part, with a relative configuration encompass all possible
enantiomers and stereoisomers of the illustrated compounds
including the stereoisomerically pure form (e.g., geometrically
pure, enantiomerically pure, or diastereomerically pure) and
enantiomeric and stereoisomeric mixtures. Enantiomeric and
stereoisomeric mixtures may be resolved into their component
enantiomers or stereoisomers using separation techniques or chiral
synthesis techniques well known to those skilled in the art.
[0049] Compounds of Formula (I)-(II) include optical isomers of
compounds of Formula (I)-(II), racemates thereof, and other
mixtures thereof. In such embodiments, the single enantiomers or
diastereomers, i.e., optically active forms, can be obtained by
asymmetric synthesis or by resolution of the racemates. Resolution
of the racemates may be accomplished, for example, by conventional
methods such as crystallization in the presence of a resolving
agent, or chromatography, using, for example, a chiral
high-pressure liquid chromatography (HPLC) column. In addition,
compounds of Formula (I)-(II) include Z- and E-forms (or cis- and
trans-forms) of compounds with double bonds.
[0050] Compounds of Formula (I)-(II) may also exist in several
tautomeric forms including the enol form, the keto form, and
mixtures thereof. Accordingly, the chemical structures depicted
herein encompass all possible tautomeric forms of the illustrated
compounds. Compounds of Formula (I)-(II) also include isotopically
labeled compounds where one or more atoms have an atomic mass
different from the atomic mass conventionally found in nature.
Examples of isotopes that may be incorporated into the compounds
disclosed herein include, but are not limited to, .sup.2H, .sup.3H,
.sup.11C, .sup.13C, .sup.14C, .sup.15N, .sup.18O, .sup.17O, etc.
Compounds as referred to herein may be free acids, salts, hydrates,
solvates, or N-oxides. Thus, when reference is made to compounds of
the present disclosure, such as compounds of Formula (I)-(II), it
is understood that a compound also implicitly refers to salts,
solvates, hydrates, and combinations of any of the foregoing.
Certain compounds may exist in multiple crystalline, cocrystalline,
or amorphous forms. Compounds of Formula (I)-(II) include
pharmaceutically acceptable solvates of a free acid or salt form of
any of the foregoing, hydrates of a free acid or salt form of any
of the foregoing, as well as crystalline forms of any of the
foregoing.
[0051] Compounds of Formula (I)-(II) also include solvates. The
term "solvate" refers to a molecular complex of a compound with one
or more solvent molecules in a stoichiometric or non-stoichiometric
amount. Such solvent molecules are those commonly used in the
pharmaceutical art, which are known to be innocuous to a patient,
e.g., water, ethanol, and the like. A molecular complex of a
compound or moiety of a compound and a solvent can be stabilized by
non-covalent intra-molecular forces such as, for example,
electrostatic forces, van der Waals forces, or hydrogen bonds. The
term "hydrate" refers to a solvate in which the one or more solvent
molecules is water.
[0052] Further, when partial structures of the compounds are
illustrated, an asterisk (*) indicates the point of bonding of the
partial structure to the rest of the molecule.
[0053] "Cycloalkyl" by itself or as part of another substituent
refers to a saturated or partially unsaturated cyclic alkyl
radical. Where a specific level of saturation is intended, the
nomenclature "cycloalkanyl" or "cycloalkenyl" is used. Examples of
cycloalkyl groups include groups derived from cyclopropane,
cyclobutane, cyclopentane, cyclohexane, and the like. In certain
embodiments, a cycloalkyl group is C.sub.3-15 cycloalkyl,
C.sub.3-12 cycloalkyl, C.sub.3-10 cycloalkyl or in certain
embodiments, C.sub.3-8 cycloalkyl. Cycloalkyl includes nonaromatic
fused ring systems.
[0054] "Cycloalkylalkyl" by itself or as part of another
substituent refers to an acyclic alkyl radical in which one of the
hydrogen atoms bonded to a carbon atom, typically a terminal or
sp.sup.3 carbon atom, is replaced with a cycloalkyl group. Where
specific alkyl moieties are intended, the nomenclature
cycloalkylalkanyl, cycloalkylalkenyl, or cycloalkylalkynyl is used.
In certain embodiments, a cycloalkylalkyl group is C.sub.7-30
cycloalkylalkyl, e.g., the alkanyl, alkenyl, or alkynyl moiety of
the cycloalkylalkyl group is C.sub.1-10 and the cycloalkyl moiety
is C.sub.6-20, and in certain embodiments, a cycloalkylalkyl group
is C.sub.7-20 cycloalkylalkyl, e.g., the alkanyl, alkenyl, or
alkynyl moiety of the cycloalkylalkyl group is C.sub.1-8 and the
cycloalkyl moiety is C.sub.4-20 or C.sub.6-12. In certain
embodiments, a cycloalkylalkyl group is C.sub.4-18
cycloalkylalkyl.
[0055] "Disease" refers to a disease, disorder, condition, or
symptom of any of the foregoing.
[0056] "Drug" as defined under 21 U.S.C. .sctn.321 (g)(1) means
"(A) articles recognized in the official United States
Pharmacopoeia, official Homeopathic Pharmacopoeia of the United
States, or official National Formulary, or any supplement to any of
them; and (B) articles intended for use in the diagnosis, cure,
mitigation, treatment, or prevention of disease in man or other
animals; and (C) articles (other than food) intended to affect the
structure or any function of the body of man or other animals . . .
"
[0057] "Halogen" refers to a fluoro, chloro, bromo, or iodo group.
In certain embodiments, halogen is fluoro, and in certain
embodiments, halogen is chloro.
[0058] "Heteroalkyl" by itself or as part of another substituent
refer to an alkyl group in which one or more of the carbon atoms
(and certain associated hydrogen atoms) are independently replaced
with the same or different heteroatomic groups. Examples of
heteroatomic groups include, but are not limited to, --O--, --S--,
--O--O--, --S--S--, --O--S--, --NR.sup.37, .dbd.N--N.dbd.,
--N.dbd.N--, --N.dbd.N--NR.sup.37--, --PR.sup.37--, --P(O).sub.2--,
--POR.sup.37--, --O--P(O).sub.2--, --SO--, --SO.sub.2--,
--Sn(R.sup.37).sub.2--, and the like, where each R.sup.37 is
independently chosen from hydrogen, C.sub.1-6 alkyl, substituted
C.sub.1-6 alkyl, C.sub.6-12 aryl, substituted C.sub.6-12 aryl,
C.sub.7-18 arylalkyl, substituted C.sub.7-18 arylalkyl, C.sub.3-7
cycloalkyl, substituted C.sub.3-7 cycloalkyl, C.sub.3-7
heterocycloalkyl, substituted C.sub.3-7 heterocycloalkyl, C.sub.1-6
heteroalkyl, substituted C.sub.1-6 heteroalkyl, C.sub.5-12
heteroaryl, substituted C.sub.5-12 heteroaryl, C.sub.6-18
heteroarylalkyl, or substituted C.sub.6-18 heteroarylalkyl.
Reference to, for example, a C.sub.1-6 heteroalkyl, means a
C.sub.1-6 alkyl group in which at least one of the carbon atoms
(and certain associated hydrogen atoms) is replaced with a
heteroatom. For example C.sub.1-6 heteroalkyl includes groups
having five carbon atoms and one heteroatom, groups having four
carbon atoms and two heteroatoms, etc. In certain embodiments, each
R.sup.37 is independently chosen from hydrogen and C.sub.1-3 alkyl.
In certain embodiments, a heteroatomic group is chosen from --O--,
--S--, --NH--, --N(CH.sub.3)--, and --SO.sub.2--.
[0059] "Heteroaryl" by itself or as part of another substituent
refers to a monovalent heteroaromatic radical derived by the
removal of one hydrogen atom from a single atom of a parent
heteroaromatic ring system. Heteroaryl encompasses multiple ring
systems having at least one heteroaromatic ring fused to at least
one other ring, which can be aromatic or non-aromatic. Heteroaryl
encompasses 5- to 7-membered aromatic, monocyclic rings containing
one or more, for example, from 1 to 4, or in certain embodiments,
from 1 to 3, heteroatoms chosen from N, O, and S, with the
remaining ring atoms being carbon; and 5- to 1 4-membered bicyclic
rings containing one or more, for example, from 1 to 4, or in
certain embodiments, from 1 to 3, heteroatoms chosen from N, O, and
S, with the remaining ring atoms being carbon, wherein at least one
of the rings is an aromatic ring, and wherein at least one
heteroatom is present in the at least one aromatic ring. For
example, heteroaryl includes a 5- to 7-membered heteroaromatic ring
fused to a 5- to 7-membered cycloalkyl ring. For such fused,
bicyclic heteroaryl ring systems wherein only one of the rings
contains one or more heteroatoms, the point of attachment may be at
the heteroaromatic ring or the cycloalkyl ring. In certain
embodiments, when the total number of N, S, and O atoms in the
heteroaryl group exceeds one, the heteroatoms are not adjacent to
one another. In certain embodiments, the total number of N, S, and
O atoms in the heteroaryl group is not more than two. In certain
embodiments, the total number of N, S, and O atoms in the aromatic
heterocycle is not more than one. In certain embodiments, a
heteroaryl group is C.sub.5-12 heteroaryl, C.sub.5-10 heteroaryl,
and in certain embodiments, C.sub.5-6 heteroaryl. The ring of a
C.sub.5-10 heteroaryl has from 4 to 9 carbon atoms, with the
remainder of the atoms in the ring being heteroatoms.
[0060] Examples of heteroaryl groups include, but are not limited
to, groups derived from acridine, arsindole, carbazole,
.beta.-carboline, chromane, chromene, quinoline, furan, imidazole,
indazole, indole, indoline, indolizine, isobenzofuran, isochromene,
isoindole, isoindoline, isoquinoline, isothiazole, isoxazole,
naphthyridine, oxadiazole, oxazole, perimidine, phenanthridine,
phenanthroline, phenazine, phthalazine, pteridine, purine, pyran,
pyrazine, pyrazole, pyridazine, pyridine, pyrimidine, pyrrole,
pyrrolizine, quinazoline, quinoline, quinolizine, quinoxaline,
tetrazole, thiadiazole, thiazole, thiophene, triazole, xanthene,
and the like. In certain embodiments, a heteroaryl group is from 5-
to 20-membered heteroaryl, in certain embodiments from 5- to
10-membered heteroaryl, and in certain embodiments from 5- to 8-
heteroaryl. In certain embodiments heteroaryl groups are those
derived from thiophene, pyrrole, benzothiophene, benzofuran,
indole, pyridine, quinoline, imidazole, oxazole, or pyrazine.
[0061] "Heteroarylalkyl" by itself or as part of another
substituent refers to an acyclic alkyl radical in which one of the
hydrogen atoms bonded to a carbon atom, is replaced with a
heteroaryl group. Typically a terminal or sp.sup.3 carbon atom is
the atom replaced with the heteroaryl group. Were specific alkyl
moieties are intended, the nomenclature "heteroarylalkanyl,"
"heteroarylalkenyl," and "heterorylalkynyl" is used. In certain
embodiments, a heteroarylalkyl group is a 6- to 20-membered
heteroarylalkyl, e.g., the alkanyl, alkenyl, or alkynyl moiety of
the heteroarylalkyl is 1- to 8-membered and the heteroaryl moiety
is a 5- to 12-membered heteroaryl, and in certain embodiments, 6-
to 14-membered heteroarylalkyl, e.g., the alkanyl, alkenyl, or
alkynyl moiety of the heteroarylalkyl is 1- to 4-membered and the
heteroaryl moiety is a 5- to 12-membered heteroaryl. In certain
embodiments, a heteroarylalkyl group is C.sub.6-18 heteroarylalkyl
and in certain embodiments, C.sub.6-10 heteroarylalkyl.
[0062] "Heterocycloalkyl" by itself or as part of another
substituent refers to a saturated or partially unsaturated cyclic
alkyl radical in which one or more carbon atoms (and any associated
hydrogen atoms) are independently replaced with the same or
different heteroatom. Typical heteroatoms to replace the carbon
atom(s) include, but are not limited to, N, P, O, S, Si, etc. Where
a specific level of saturation is intended, the nomenclature
"heterocycloalkanyl" or "heterocycloalkenyl" is used. Examples of
heterocycloalkyl groups include, but are not limited to, groups
derived from epoxides, azirines, thiiranes, imidazolidine,
morpholine, piperazine, piperidine, pyrazolidine, pyrrolidine,
quinuclidine, and the like. Heterocycloalkyl includes nonaromatic
heterocycloalkyl fused ring systems. In certain embodiments, a
heterocycloalkyl group is a C.sub.3-12 heterocycloalkylalkyl,
C.sub.3-10 heterocycloalkylalkyl, and in certain embodiments
C.sub.3-8 heterocycloalkyalkyl.
[0063] "Heterocycloalkyalkyl" by itself or as part of another
substituent refers to an acyclic alkyl radical in which one of the
hydrogen atoms bonded to a carbon atom, is replaced with a
heterocycloalkyl group as defined herein. In certain embodiments, a
heterocycloalkylalkyl group is a C.sub.4-18 heterocycloalkylalkyl,
C.sub.4-12 heterocycloalkylalkyl, and in certain embodiments
C.sub.4-10 heterocycloalkyalkyl.
[0064] "Metabolic intermediate" refers to a compound that is formed
in vivo by metabolism of a parent compound and that further
undergoes reaction in vivo to release an active agent. Compounds of
Formula (I) are protected carboxylate nucleophile prodrugs of
acamprosate that are metabolized in vivo to provide the
corresponding metabolic intermediates of Formula (II). Metabolic
intermediates of Formula (II) undergo nucleophilic cyclization to
release acamprosate and one or more reaction products. It is
desirable that the reaction products or metabolites thereof not be
toxic.
[0065] "Neopentyl" refers to a radical in which a methylene carbon
is bonded to a carbon atom, which is bonded to three non-hydrogen
substituents. Examples of non-hydrogen substituents include carbon,
oxygen, nitrogen, and sulfur. In certain embodiments, each of the
three non-hydrogen substituents is carbon. In certain embodiments,
two of the three non-hydrogen substituents is carbon, and the third
non-hydrogen substituent is chosen from oxygen and nitrogen. In
certain embodiments, a neopentyl group has the structure:
##STR00004##
where R.sup.a and R.sup.b are independently chosen from C.sub.1-4
alkyl, substituted C.sub.1-4 alkyl, C.sub.1-4 alkoxy, and
substituted C.sub.1-4 alkoxy; or R.sup.3 and R.sup.4 together with
the carbon to which they are bonded form a ring chosen from a
C.sub.3-10 cycloalkyl, substituted C.sub.3-10 cycloalkyl,
C.sub.3-10 heterocycloalkyl, and substituted C.sub.3-10
heterocycloalkyl ring; and R.sup.c is chosen from carbon, nitrogen,
and oxygen. In certain embodiments, each of R.sup.a and R.sup.b is
methyl; and R.sup.c is chosen from carbon, nitrogen, and oxygen. In
certain embodiments, each of R.sup.a and R.sup.b is methyl; and
R.sup.c is carbon; in certain embodiments, nitrogen; and in certain
embodiments, oxygen.
[0066] "Parent aromatic ring system" refers to an unsaturated
cyclic or polycyclic ring system having a conjugated .pi. (pi)
electron system. Included within the definition of "parent aromatic
ring system" are fused ring systems in which one or more of the
rings are aromatic and one or more of the rings are saturated or
unsaturated, such as, for example, fluorene, indane, indene,
phenalene, etc. Examples of parent aromatic ring systems include,
but are not limited to, aceanthrylene, acenaphthylene,
acephenanthrylene, anthracene, azulene, benzene, chrysene,
coronene, fluoranthene, fluorene, hexacene, hexaphene, hexalene,
as-indacene, s-indacene, indane, indene, naphthalene, octacene,
octaphene, octalene, ovalene, penta-2,4-diene, pentacene,
pentalene, pentaphene, perylene, phenalene, phenanthrene, picene,
pleiadene, pyrene, pyranthrene, rubicene, triphenylene,
trinaphthalene, and the like.
[0067] "Parent heteroaromatic ring system" refers to an aromatic
ring system in which one or more carbon atoms (and any associated
hydrogen atoms) are independently replaced with the same or
different heteroatom in such a way as to maintain the continuous
.pi. (pi)-electron system characteristic of aromatic systems and a
number or out-of-plane .pi. (pi)-electrons corresponding to the
Huckel rule (4n+1). Examples of heteroatoms to replace the carbon
atoms include, but are not limited to, N, P, O, S, and Si, etc. In
certain embodiments, a heteroatom is chosen from N, O, and S.
Specifically included within the definition of "parent
heteroaromatic ring systems" are fused ring systems in which one or
more of the rings are aromatic and one or more of the rings are
saturated or unsaturated, such as, for example, arsindole,
benzodioxan, benzofuran, chromane, chromene, indole, indoline,
xanthene, etc. Examples of parent heteroaromatic ring systems
include, but are not limited to, arsindole, carbazole,
.beta.-carboline, chromane, chromene, cinnoline, furan, imidazole,
indazole, indole, indoline, indolizine, isobenzofuran, isochromene,
isoindole, isoindoline, isoquinoline, isothiazole, isoxazole,
naphthyridine, oxadiazole, oxazole, perimidine, phenanthridine,
phenanthroline, phenazine, phthalazine, pteridine, purine, pyran,
pyrazine, pyrazole, pyridazine, pyridine, pyrimidine, pyrrole,
pyrrolizine, quinazoline, quinoline, quinolizine, quinoxaline,
tetrazole, thiadiazole, thiazole, thiophene, triazole, xanthene,
and the like.
[0068] "Patient" refers to a mammal, for example, a human.
[0069] "Pharmaceutically acceptable" refers to approved or
approvable by a regulatory agency of the Federal or a state
government or listed in the U.S. Pharmacopoeia or other generally
recognized pharmacopoeia for use in animals, and more particularly
in humans.
[0070] "Pharmaceutically acceptable salt" refers to a salt of a
compound, which possesses the desired pharmacological activity of
the parent compound. Such salts include acid addition salts, formed
with inorganic acids such as hydrochloric acid, hydrobromic acid,
sulfuric acid, nitric acid, phosphoric acid, and the like; or
formed with organic acids such as acetic acid, propionic acid,
hexanoic acid, cyclopentanepropionic acid, glycolic acid, pyruvic
acid, lactic acid, malonic acid, succinic acid, malic acid, maleic
acid, fumaric acid, tartaric acid, citric acid, benzoic acid,
3-(4-hydroxybenzoyl)benzoic acid, cinnamic acid, mandelic acid,
methanesulfonic acid, ethanesulfonic acid, 1,2-ethane-disulfonic
acid, 2-hydroxyethanesulfonic acid, benzenesulfonic acid,
4-chlorobenzenesulfonic acid, 2-naphthalenesulfonic acid,
4-toluenesulfonic acid, camphorsulfonic acid,
4-methylbicyclo[2.2.2]-oct-2-ene-1-carboxylic acid, glucoheptonic
acid, 3-phenylpropionic acid, trimethylacetic acid, tertiary
butylacetic acid, lauryl sulfuric acid, gluconic acid, glutamic
acid, hydroxynaphthoic acid, salicylic acid, stearic acid, muconic
acid, and the like; and salts formed when an acidic proton present
in the parent compound is replaced by a metal ion, e.g., an alkali
metal ion, an alkaline earth ion, or an aluminum ion; or
coordinates with an organic base such as ethanolamine,
diethanolamine, triethanolamine, N-methylglucamine, and the like.
In certain embodiments, pharmaceutically acceptable addition salts
include metal salts such as sodium, potassium, aluminum, calcium,
magnesium and zinc salts, and ammonium salts such as
isopropylamine, diethylamine, and diethanolamine salts. In certain
embodiments, a pharmaceutically acceptable salt is the
hydrochloride salt. In certain embodiments, a pharmaceutically
acceptable salt is the sodium salt. Pharmaceutically acceptable
salts may be prepared by the skilled chemist, by treating, for
example, a compound of Formula (I) with an appropriate base in a
suitable solvent, followed by crystallization and filtration.
[0071] "Pharmaceutically acceptable vehicle" refers to a
pharmaceutically acceptable diluent, a pharmaceutically acceptable
adjuvant, a pharmaceutically acceptable excipient, a
pharmaceutically acceptable carrier, or a combination of any of the
foregoing with which a compound provided by the present disclosure
may be administered to a patient and which does not destroy the
pharmacological activity thereof and which is non-toxic when
administered in doses sufficient to provide a therapeutically
effective amount of the compound.
[0072] "Pharmaceutical composition" refers to at least one compound
of Formula (I) and at least one pharmaceutically acceptable vehicle
with which the at least one compound of Formula (I) is administered
to a patient.
[0073] "Prodrug" refers to a derivative of a drug molecule that
requires a transformation within the body to release the active
drug. Prodrugs are frequently, although not necessarily,
pharmacologically inactive until converted to the parent drug.
Prodrugs may be obtained by bonding a promoiety (defined herein)
typically via a functional group, to a drug. For example, referring
to compounds of Formula (I), the promoiety is bonded to the drug,
acamprosate, via the sulfonic acid functional group of acamprosate.
Compounds of Formula (I) are prodrugs of acamprosate that can be
metabolized within a patient's body to release acamprosate.
[0074] "Promoiety" refers to a group bonded to a drug, typically to
a functional group of the drug, via bond(s) that are cleavable
under specified conditions of use. The bond(s) between the drug and
promoiety may be cleaved by enzymatic or non-enzymatic means. Under
the conditions of use, for example following administration to a
patient, the bond(s) between the drug and promoiety may be cleaved
to release the parent drug. The cleavage of the promoiety may
proceed spontaneously, such as via a hydrolysis reaction, or it may
be catalyzed or induced by another agent, such as by an enzyme, by
light, by acid, or by a change of or exposure to a physical or
environmental parameter, such as a change of temperature, pH, etc.
The agent may be endogenous to the conditions of use, such as an
enzyme present in the systemic circulation of a patient to which
the prodrug is administered or the acidic conditions of the stomach
or the agent may be supplied exogenously. For example, for a
prodrug of Formula (I), the drug is acamprosate (1) and the
promoiety has the structure:
##STR00005##
where n, R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are is defined
herein.
[0075] "Protecting group" refers to a grouping of atoms, which when
attached to a reactive group in a molecule masks, reduces, or
prevents that reactivity. Examples of amino protecting groups
include, but are not limited to, formyl, acetyl, trifluoroacetyl,
benzyl, benzyloxycarbonyl (CBZ), tert-butoxycarbonyl (Boc),
trimethylsilyl (TMS), 2-trimethylsilyl-ethanesulfonyl (SES), trityl
and substituted trityl groups, allyloxycarbonyl,
9-fluorenylmethyloxycarbonyl (FMOC), nitro-veratryloxycarbonyl
(NVOC), and the like. Examples of hydroxy protecting groups
include, but are not limited to, those in which the hydroxy group
is either acylated or alkylated such as benzyl, and trityl ethers
as well as alkyl ethers, tetrahydropyranyl ethers, trialkylsilyl
ethers, and allyl ethers.
[0076] "Salt" refers to a chemical compound consisting of an
assembly of cations and anions. Salts of a compound of the present
disclosure include stoichiometric and non-stoichiometric forms of
the salt. In certain embodiments, because of its potential use in
medicine, salts of a compound of Formula (I) are pharmaceutically
acceptable salts.
[0077] "Substituted" refers to a group in which one or more
hydrogen atoms are independently replaced with the same or
different substituent group(s). Examples of substituent groups
include, but are not limited to, -M, --R.sup.60, --O.sup.-, .dbd.O,
--OR.sup.60, --SR.sup.60, --S.sup.-, .dbd.S, --NR.sup.60R.sup.61,
.dbd.NR.sup.60, --CF.sub.3, --CN, --OCN, --SCN, --NO, --NO.sub.2,
.dbd.N.sub.2, --N.sub.3, --S(O).sub.2O.sup.-, --S(O).sub.2OH,
--S(O).sub.2R.sup.60, --OS(O.sub.2)O.sup.-, --OS(O).sub.2R.sup.60,
--P(O)(O.sup.60).sub.2, --P(O)(OR.sup.60)(O.sup.-),
--OP(O)(OR.sup.60)(OR.sup.61), --C(O)R.sup.60, --C(S)R.sup.60,
--C(O)OR.sup.60, --C(O)NR.sup.60R.sup.61, --C(O)O.sup.-,
--C(S)OR.sup.60, --NR.sup.62C(O)NR.sup.60R.sup.61,
--NR.sup.62C(S)NR.sup.60R.sup.61,
--NR.sup.62C(NR.sup.63)NR.sup.60R.sup.61, and
--C(NR.sup.62)NR.sup.60R.sup.61 where M is halogen; R.sup.60,
R.sup.61, R.sup.62, and R.sup.63 are independently chosen from
hydrogen, alkyl, alkoxy, cycloalkyl, heterocycloalkyl, aryl, and
heteroaryl, or R.sup.60 and R.sup.61 together with the nitrogen
atom to which they are bonded form a ring chosen from a
heterocycloalkyl ring. In certain embodiments, R.sup.60, R.sup.61,
R.sup.62, and R.sup.63 are independently chosen from hydrogen,
C.sub.1-6 alkyl, C.sub.1-6 alkoxy, C.sub.3-12 cycloalkyl,
C.sub.3-12 heterocycloalkyl, C.sub.6-12 aryl, and C.sub.6-12
heteroaryl. In certain embodiments, each substituent group is
independently chosen from halogen, --OH, --CN, --CF.sub.3, .dbd.O,
--NO.sub.2, C.sub.1-3 alkoxy, C.sub.1-3 alkyl, --COOR.sup.64
wherein R.sup.64 is chosen from hydrogen and C.sub.1-3 alkyl, and
--N(R.sup.65).sub.2 wherein each R.sup.65 is independently chosen
from hydrogen and C.sub.1-3 alkyl. In certain embodiments, each
substituent group is independently chosen from halogen, --OH, --CN,
--CF.sub.3, --OCF.sub.3, .dbd.O, --NO.sub.2, C.sub.1-6 alkoxy,
C.sub.1-6 alkyl, --COOR.sup.26, --N(R.sup.27).sub.2, and
--CON(R.sup.28).sub.2; wherein each of R.sup.26, R.sup.27, and
R.sup.28 is independently chosen from hydrogen and C.sub.1-6
alkyl.
[0078] In certain embodiments, each substituent group is
independently chosen from halogen, --OH, --CN, --CF.sub.3, .dbd.O,
--NO.sub.2, C.sub.1-3 alkoxy, C.sub.1-3 alkyl, --COOR.sup.12
wherein R.sup.12 is chosen from hydrogen and C.sub.1-3 alkyl, and
--N(R.sup.12).sub.2 wherein each R.sup.12 is independently chosen
from hydrogen and C.sub.1-3 alkyl. In certain embodiments, each
substituent group is independently chosen from halogen, --OH, --CN,
--CF.sub.3, --OCF.sub.3, .dbd.O, --NO.sub.2, C.sub.1-6 alkoxy,
C.sub.1-6 alkyl, --COOR.sup.12, --N(R.sup.12).sub.2, and
--CONR.sup.12.sub.2; wherein each R.sup.12 is independently chosen
from hydrogen and C.sub.1-6 alkyl. In certain embodiments, each
substituent group is chosen from C.sub.1-4 alkyl, --OH, and
--NH.sub.2.
[0079] "Sustained release" refers to release of a compound from a
dosage form of a pharmaceutical composition at a rate effective to
achieve a therapeutic or prophylactic concentration of the compound
or active metabolite thereof, in the systemic circulation of a
patient over a prolonged period of time relative to that achieved
by administration of an immediate release formulation of the same
compound by the same route of administration. In some embodiments,
release of a compound occurs over a time period of at least about 4
hours, such as at least about 8 hours, at least about 12 hours, at
least about 16 hours, at least about 20 hours, and in some
embodiments, at least about 24 hours.
[0080] "Treating" or "treatment" of any disease refers to arresting
or ameliorating a disease or at least one of the clinical symptoms
of a disease or disorder, reducing the risk of acquiring a disease
or at least one of the clinical symptoms of a disease, reducing the
development of a disease or at least one of the clinical symptoms
of the disease or reducing the risk of developing a disease or at
least one of the clinical symptoms of a disease. "Treating" or
"treatment" also refers to inhibiting the disease, either
physically, (e.g., stabilization of a discernible symptom),
physiologically, (e.g., stabilization of a physical parameter), or
both, and to inhibiting at least one physical parameter that may or
may not be discernible to the patient. In certain embodiments,
"treating" or "treatment" refers to delaying the onset of the
disease or at least one or more symptoms thereof in a patient which
may be exposed to or predisposed to a disease or disorder even
though that patient does not yet experience or display symptoms of
the disease.
[0081] "Therapeutically effective amount" refers to the amount of a
compound that, when administered to a subject for treating a
disease, or at least one of the clinical symptoms of a disease, is
sufficient to affect such treatment of the disease or symptom
thereof. The "therapeutically effective amount" may vary depending,
for example, on the compound, the disease and/or symptoms of the
disease, severity of the disease and/or symptoms of the disease or
disorder, the age, weight, and/or health of the patient to be
treated, and the judgment of the prescribing physician. An
appropriate amount in any given instance may be ascertained by
those skilled in the art or capable of determination by routine
experimentation.
[0082] "Therapeutically effective dose" refers to a dose that
provides effective treatment of a disease or disorder in a patient.
A therapeutically effective dose may vary from compound to
compound, and from patient to patient, and may depend upon factors
such as the condition of the patient and the route of delivery. A
therapeutically effective dose may be determined in accordance with
routine pharmacological procedures known to those skilled in the
art.
[0083] Reference is now made in detail to certain embodiments of
compounds, compositions, and methods. The disclosed embodiments are
not intended to be limiting of the claims. To the contrary, the
claims are intended to cover all alternatives, modifications, and
equivalents.
Compounds
[0084] Certain embodiments provide a compound of Formula (I):
##STR00006## [0085] or a pharmaceutically acceptable salt thereof;
wherein: [0086] n is chosen from 0, 1, 2, and 3; [0087] R.sup.1 is
chosen from C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl,
C.sub.6-10 aryl, substituted C.sub.6-10 aryl, C.sub.3-8 cycloalkyl,
substituted C.sub.3-8 cycloalkyl, C.sub.7-18 arylalkyl, substituted
C.sub.7-18 arylalkyl, C.sub.4-16 cycloalkylalkyl, substituted
C.sub.4-16 cycloalkylalkyl, C.sub.1-8 heteroalkyl, substituted
C.sub.1-8 heteroalkyl, C.sub.5-10 heteroaryl, substituted
C.sub.5-10 heteroaryl, C.sub.3-8 heterocycloalkyl, substituted
C.sub.3-8 heterocycloalkyl, C.sub.6-18 heteroarylalkyl, substituted
C.sub.6-18 heteroarylalkyl, C.sub.4-16 heterocycloalkylalkyl,
substituted C.sub.4-16 heterocycloalkylalkyl,
--C(R.sup.6).sub.2OC(O)R.sup.5, --C(R.sup.6).sub.2OC(O)OR.sup.5,
--(CH.sub.2).sub.rN(R.sup.6).sub.2, and
--(CH.sub.2).sub.rC(O)N(R.sup.6).sub.2, wherein: [0088] r is chosen
from 1, 2 and 3; [0089] each R.sup.5 is independently chosen from
C.sub.1-6 alkyl, substituted C.sub.1-6 alkyl, C.sub.6-8 aryl,
substituted C.sub.6-8 aryl, C.sub.3-8 cycloalkyl, substituted
C.sub.3-8 cycloalkyl, C.sub.1-6 heteroalkyl, substituted C.sub.1-6
heteroalkyl, C.sub.5-8 heteroaryl, substituted C.sub.5-8
heteroaryl, C.sub.3-8 heterocycloalkyl, and substituted C.sub.3-8
heterocycloalkyl; and [0090] each R is independently chosen from
hydrogen, C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl, C.sub.6-8
aryl, substituted C.sub.6-8 aryl, C.sub.3-8 cycloalkyl, substituted
C.sub.3-8 cycloalkyl, and --COOR.sup.33; wherein R.sup.33 is chosen
from hydrogen and C.sub.1-8 alkyl; [0091] R.sup.2 and R.sup.3 are
independently chosen from C.sub.1-4 alkyl, substituted C.sub.1-4
alkyl, C.sub.1-4 alkoxy, substituted C.sub.1-4 alkoxy, --NH.sub.2,
--NHC(O)R.sup.34, --NHR.sup.34, and --N(R.sup.34).sub.2; or R.sup.2
and R.sup.3 together with the carbon to which they are bonded form
a ring chosen from a C.sub.3-8 cycloalkyl, substituted C.sub.3-8
cycloalkyl, C.sub.3-8 heterocycloalkyl, and substituted C.sub.3-8
heterocycloalkyl ring; and [0092] each R.sup.4 is independently
chosen from hydrogen, halogen, --OR.sup.7, --CN, --CF.sub.3,
.dbd.O, --NO.sub.2, --COOR.sup.33, C.sub.1-8 alkyl, substituted
C.sub.1-8 alkyl, C.sub.6-10 aryl, substituted C.sub.6-10 aryl,
C.sub.3-8 cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.7-18
arylalkyl, substituted C.sub.7-18 arylalkyl, C.sub.4-16
cycloalkylalkyl, substituted C.sub.4-16 cycloalkylalkyl, C.sub.1-8
heteroalkyl, substituted C.sub.1-8 heteroalkyl, C.sub.5-10
heteroaryl, substituted C.sub.5-10 heteroaryl, C.sub.3-8
heterocycloalkyl, substituted C.sub.3-8 heterocycloalkyl,
C.sub.6-18 heteroarylalkyl, substituted C.sub.6-18 heteroarylalkyl,
C.sub.4-16 heterocycloalkylalkyl, substituted C.sub.4-16
heterocycloalkylalkyl, --NH.sub.2, --NHC(O)R.sup.34, and
--N(R.sup.34).sub.2; wherein: [0093] R.sup.7 is chosen from
hydrogen, C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl, C.sub.6-10
aryl, C.sub.6-10 substituted aryl, C.sub.3-8 cycloalkyl,
substituted C.sub.3-8 cycloalkyl, --C(O)R.sup.8, --C(O)OR.sup.8,
--C(O)N(R.sup.9).sub.2, --C(O)SR.sup.8,
--C(R.sup.9).sub.2OC(O)R.sup.8, --C(R.sup.9).sub.2OC(O)OR.sup.8,
--P(O)(OH).sub.2, and --SO.sub.2OH; wherein: [0094] each R.sup.8 is
independently chosen from C.sub.1-6 alkyl, substituted C.sub.1-6
alkyl, C.sub.6-8 aryl, substituted C.sub.6-8 aryl, C.sub.3-8
cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.1-6
heteroalkyl, substituted C.sub.1-6 heteroalkyl, C.sub.5-8
heteroaryl, substituted C.sub.5-8 heteroaryl, C.sub.3-8
heterocycloalkyl, and substituted C.sub.3-8 heterocycloalkyl; and
[0095] each R.sup.9 is independently chosen from hydrogen,
C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl, C.sub.6-8 aryl,
substituted C.sub.6-8 aryl, C.sub.3-8 cycloalkyl, substituted
C.sub.3-8 cycloalkyl, and --COOR.sup.35; wherein R.sup.35 is chosen
from hydrogen and C.sub.1-8 alkyl; [0096] R.sup.33 is chosen from
hydrogen and C.sub.1-4 alkyl; [0097] each R.sup.34 is independently
chosen from hydrogen, C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl,
C.sub.1-8 alkoxy, substituted C.sub.1-8 alkoxy, C.sub.6-10 aryl,
substituted C.sub.6-10 aryl, C.sub.6-10 aryloxy, substituted
C.sub.6-10 aryloxy, C.sub.3-8 cycloalkyl, substituted C.sub.3-8
cycloalkyl, C.sub.3-8 cycloalkoxy, substituted C.sub.3-8
cycloalkoxy, C.sub.7-18 arylalkyl, substituted C.sub.7-18
arylalkyl, C.sub.4-16 cycloalkylalkyl, substituted C.sub.4-16
cycloalkylalkyl, C.sub.1-8 heteroalkyl, substituted C.sub.1-8
heteroalkyl, C.sub.5-10 heteroaryl, substituted C.sub.5-10
heteroaryl, C.sub.3-8 heterocycloalkyl, substituted C.sub.3-8
heterocycloalkyl, C.sub.6-18 heteroarylalkyl, substituted
C.sub.6-18 heteroarylalkyl, C.sub.4-16 heterocycloalkylalkyl, and
substituted C.sub.4-16 heterocycloalkylalkyl; and [0098] with the
proviso that when n is 1, and each of R.sup.2 and R.sup.3 is
methyl; then R.sup.4 is not chosen from --OR.sup.7, --COOR.sup.33,
and substituted heteroalkyl.
[0099] In certain embodiments of a compound of Formula (I), each
substituent is independently chosen from halogen, --OH, --CN,
--CF.sub.3, --OCF.sub.3, .dbd.O, --NO.sub.2, C.sub.1-6 alkoxy,
C.sub.1-6 alkyl, --COOR.sup.30, --N(R.sup.31).sub.2, and
--CON(R.sup.32).sub.2; wherein each R.sup.30, R.sup.31, and
R.sup.32 is independently chosen from hydrogen and C.sub.1-6 alkyl.
In certain embodiments of a compound of Fonnula (I), each
substituent is independently chosen from C.sub.1-4 alkyl, C.sub.1-4
alkoxy, --OH, and --NH.sub.2.
[0100] In certain embodiments of a compound of Formula (I), n is
chosen from 0, 1, and 2. In certain embodiments of a compound of
Formula (I), n is 0, n is 1, n is 2, and in certain embodiments, n
is 3.
[0101] In certain embodiments of a compound of Formula (I), R.sup.1
is chosen from C.sub.1-6 alkyl, substituted C.sub.1-6 alkyl,
C.sub.3-8 cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.6-10
aryl, substituted C.sub.6-10 aryl, C.sub.7-12 arylalkyl,
substituted C.sub.7-12 arylalkyl, C.sub.1-6 heteroalkyl,
substituted C.sub.1-6 heteroalkyl, C.sub.3-8 heterocycloalkyl,
substituted C.sub.3-8 heterocycloalkyl, C.sub.5-10 heteroaryl,
substituted C.sub.5-10 heteroaryl, C.sub.6-12 heteroarylalkyl, and
substituted C.sub.6-12 heteroarylalkyl. In certain embodiments of a
compound of Formula (I), R.sup.1 is chosen from C.sub.1-6 alkyl,
C.sub.3-8 cycloalkyl, C.sub.6-10 aryl, C.sub.7-12 arylalkyl,
C.sub.1-6 heteroalkyl, C.sub.3-8 heterocycloalkyl, C.sub.5-10
heteroaryl, and C.sub.6-12 heteroarylalkyl. In certain embodiments
of a compound of Formula (I), R.sup.1 is chosen from C.sub.1-6
alkyl, C.sub.3-8 cycloalkyl, C.sub.6-10 aryl, and C.sub.7-12
arylalkyl.
[0102] In certain embodiments of a compound of Formula (I), R.sup.1
is chosen from --C(R.sup.6).sub.2OC(O)R.sup.5 and
--C(R.sup.6).sub.2OC(O)OR.sup.5.
[0103] In certain embodiments of a compound of Formula (I), R.sup.1
is chosen from --C(R.sup.6).sub.2OC(O)R.sup.5 and
--C(R.sup.6).sub.2OC(O)OR.sup.5; R.sup.5 is chosen from C.sub.1-6
alkyl, substituted C.sub.1-6 alkyl, C.sub.6-8 aryl, substituted
C.sub.6-8 aryl, C.sub.3-8 cycloalkyl, substituted C.sub.3-8
cycloalkyl, C.sub.1-6 heteroalkyl, substituted C.sub.1-6
heteroalkyl, C.sub.5-8 heteroaryl, substituted C.sub.5-8
heteroaryl, C.sub.3-8 heterocycloalkyl, and substituted C.sub.3-8
heterocycloalkyl; and each R.sup.6 is independently chosen from
hydrogen, C.sub.1-6 alkyl, substituted C.sub.1-6 alkyl, C.sub.6-8
aryl, substituted C.sub.6-8 aryl, C.sub.3-8 cycloalkyl, and
substituted C.sub.3-8 cycloalkyl.
[0104] In certain embodiments of a compound of Formula (I), R.sup.1
is chosen from --C(R.sup.6).sub.2OC(O)R.sup.5 and
--C(R.sup.6).sub.2OC(O)OR.sup.5; R.sup.5 is chosen from C.sub.1-6
alkyl and C.sub.6-8 aryl; and each R.sup.6 is independently chosen
from hydrogen, C.sub.1-6 alkyl, and C.sub.6-8 aryl.
[0105] In certain embodiments of a compound of Formula (I) wherein
R.sup.1 is chosen from --C(R.sup.6).sub.2OC(O)R.sup.5 and
--C(R.sup.6).sub.2OC(O)OR.sup.5; R.sup.5 is chosen from methyl,
ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl,
cyclohexyl, phenyl, and 3-pyridyl; and one of R.sup.6 is hydrogen
and the other of R.sup.6 is chosen from hydrogen, methyl, ethyl,
n-propyl, isopropyl, cyclohexyl, and phenyl; or each of R.sup.6 is
methyl. In certain of the immediately preceding embodiments, each
of R.sup.2 and R.sup.3 is methyl. In certain of the immediately
preceding embodiments, each R.sup.4 is hydrogen.
[0106] In certain embodiments of a compound of Formula (I), R.sup.1
is chosen from C.sub.1-6 alkyl, benzyl, substituted benzyl,
morpholinyl-N-ethyl, pyridyl-3-methyl, ethoxycarbonyloxyethyl, and
methylbenzyl.
[0107] In certain embodiments of a compound of Formula (I), R.sup.2
and R.sup.3 are independently chosen from C.sub.1-4 alkyl,
substituted C.sub.1-4 alkyl, C.sub.1-4 alkoxy, substituted
C.sub.1-4alkoxy, and --NH.sub.2.
[0108] In certain embodiments of a compound of Formula (I), each of
R.sup.2 and R.sup.3 is methyl.
[0109] In certain embodiments of a compound of Formula (I), R.sup.2
is methyl; and R.sup.3is chosen from
--OSO.sub.2(CH.sub.2).sub.3NHC(O)CH.sub.3, --NH.sub.3.sup.+X.sup.-,
and --CH.sub.2OH, where X is halogen.
[0110] In certain embodiments of a compound of Formula (I), each
R.sup.4 is independently chosen from hydrogen, halogen, --CN,
--CF.sub.3, .dbd.O, --NO.sub.2, C.sub.1-6 alkoxy, C.sub.1-6 alkyl,
--COOR.sup.33, and --N(R.sup.34).sub.2; wherein R.sup.33 is chosen
from hydrogen and C.sub.1-3 alkyl; and each R.sup.34 is
independently chosen from hydrogen and C.sub.1-3 alkyl.
[0111] In certain embodiments of a compound of Formula (I), each
R.sup.4 is independently chosen from hydrogen and C.sub.1-4 alkyl.
In certain embodiments of a compound of Fonnula (I), each R.sup.4is
hydrogen.
[0112] In certain embodiments of a compound of Formula (I), R.sup.1
is chosen from C.sub.1-6 alkyl, morpholinyl-N-ethyl,
N,N-dimethylaminoethyl, benzyl, and methylbenzyl. In certain
embodiments, R.sup.1 is chosen from methyl, ethyl, n-propyl,
isopropyl, 1-butyl, sec-butyl, tert-butyl, isobutyl, pentyl,
cyclohexyl, phenyl, and benzyl.
[0113] In certain embodiments of a compound of Formula (I), R.sup.1
is chosen from C.sub.1-4 alkyl, cyclohexyl, phenyl, benzyl, and
cyclohexylmethyl; n is chosen from 0, 1, and 2; each R.sup.4 is
hydrogen; and each of R.sup.2 and R.sup.3 is methyl.
[0114] In certain embodiments of a compound of Formula (I), the
stereochemistry of the carbon atom to which R.sup.4is bonded is of
the (S)-configuration.
[0115] In certain embodiments of a compound of Formula (I), the
stereochemistry of the carbon atom to which R.sup.4 is bonded is of
the (R)-configuration.
[0116] In certain embodiments, R.sup.1 is chosen from a
carboxyl-protecting group that is cleavable in vivo by enzymatic or
chemical means to provide the corresponding amide metabolic
intermediate. When cleaved in vivo, the amide-protecting group
provides a non-toxic metabolite. Examples of carboxyl-protecting
groups include 2-N-(morpholino)ethyl, choline, methyl,
methoxyethyl, 9-fluorenylmethyl, methoxymethyl, methylthiomethyl,
tetrahydropyranyl, tetrahydrofuranyl, methoxyethoxymethyl,
2-(trimethylsilyl)ethoxymethyl, benzyloxymethyl, pivaloyloxymethyl,
phenylacetoxymethyl, triisopropylsilylmethyl, cyanomethyl, acetol,
p-bromophenacyl. .alpha.-methylphenacyl, p-methoxyphenacyl, desyl,
carboxamidomethyl, p-azobenzenecarboxamido-methyl,
N-phthalimidomethyl, (methoxyethoxy)ethyl, 2,2,2-trichloroethyl,
2-fluoroethyl, 2-chloroethyl, 2-bromoethyl, 2-iodoethyl,
4-chlorobutyl, 5-chloropentyl, 2-(trimethylsilyl)ethyl,
2-methylthioethyl, 1,3-dithianyl-2-methyl,
2-(p-nitrophenylsulfenyl)ethyl, 2-(p-toluenesulfonyl)ethyl,
2-(2'-pyridyl)ethyl, 2-(p-methoxyphenyl)ethyl,
2-(diphenylphosphino)ethyl, 1-methyl-1-phenylethyl,
2-(4-acetyl-2-nitrophenyl)ethyl, 2-cyanoethyl, heptyl, tert-butyl,
3-methyl-3-pentyl, dicyclopropylmethyl, 2,4-dimethyl-3-pentyl,
cyclopentyl, cyclohexyl, allyl, methallyl, 2-methylbut-3-en-2-yl,
3-methylbut-2-(prenyl), 3-buten-1-yl,
4-(trimethylsilyl)-2-buten-1-yl, cirnamyl, .alpha.-methylcinnamyl,
propargyl, phenyl, 2,6-dimethylphenyl, 2,6-diisopropylphenyl,
2,6-di-tert-butyl-4-methylphenyl,
2,6-di-tert-butyl-4-methoxyphenyl, p-(methylthio)phenyl,
pentafluorophenyl, benzyl, triphenylmethyl, diphenylmethyl,
bis(o-nitrophenyl)methyl, 9-anthrylmethyl,
2-(9,10-dioxo)anthrylmethyl. 5-dibenzosuberyl, 1-pyrenylmethyl,
2-(trifluoromethyl)-6-chromonylmethyl, 2,4,6-trimethylbenzyl,
p-bromobenzyl, o-nitrobenzyl, p-nitrobenzyl, p-methoxybenzyl,
2.6-dimethoxybenzyl, 4-(methylsulfinyl)benzyl, 4-sulfobenzyl,
4-azidomethoxybenzyl,
4-{a/-[1-(4,4-dimethyl-2,6-dioxocyclohexylidene)-3-methylbutyl]amino}benz-
yl, piperonyl, 4-picolyl, trimethyisilyl, triethylsilyl,
tert-butyldimethylsilyl, isopropyldimethylsilyl,
phenyidimethylsilyl, di-tert-butylmethylsilyl, triisopropylsilyl,
and the like. Other carboxyl-protecting groups are known in the
art.
[0117] In certain embodiments of a compound of Formula (I), the
compound is an embodiment of Formula (I) described herein with the
proviso that when n is 1 and each of R.sup.2 and R.sup.3 is
C.sub.1-4 alkyl, then R.sup.4 is not chosen from --OR.sup.7,
--COOR.sup.33, and substituted heteroalkyl.
[0118] In certain embodiments of a compound of Formula (1), the
compound is chosen from: [0119] methyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
[0120] phenylmethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
[0121] phenylmethyl
5-{[3-(acetylamino)propyl]sulfonyloxy}-4,4-dimethylpentanoate;
[0122] phenylmethyl
4-{[3-(acetylamino)propyl]sulfonyloxy}-3,3-dimethylbutanoate;
[0123] phenylmethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2-({[3-(acetylamino)propyl]sulfony-
loxy}methyl)-2-methylpropanoate; [0124] (4-methoxyphenyl)methyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
[0125] ethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
[0126] methylethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
[0127] 2'-morpholinylethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
hydrochloride; [0128] pyridinylmethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
hydrochloride; [0129] ethoxycarbonyloxyethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
[0130] phenylmethyl
2-({[3-(acetylamino)propyl]sulfonyloxy}methyl)-3-hydroxy-2-methylpropanoa-
te; [0131] methyl
4-{[3-(acetylamino)propyl]sulfonyloxy}-3,3-dimethylbutanoate;
[0132] 3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoic
acid; [0133]
5-{[3-(acetylamino)propyl]sulfonyloxy}-4,4-dimethylpentanoic acid;
[0134] methylethoxycarbonyloxyethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate;
[0135] 4-{[3-(acetylamino)propyl]sulfonyloxy-3,3-dimethylbutanoic
acid; [0136] methyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2-[(tert-butoxy)carbonylami-
no]-2-methylpropanoate; [0137] methyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2-amino-2-methyl propanoate;
[0138] ethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-diethoxypropanoate;
[0139] benzyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-diethoxypropanoate; and
[0140] a phanmaceutically acceptable salt of any of the
foregoing.
[0141] In certain embodiments of a compound of Formula (I), the
compound is chosen from: [0142] phenylmethyl 3-{[3-(acetyl
amino)propyl]sulfonyloxy}-2,2-dimethylpropanoate; [0143] ethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate; and
[0144] a pharmaceutically acceptable salt of any of the
foregoing.
[0145] Certain embodiments provide a compound of Formula (II):
##STR00007## [0146] or a pharmaceutically acceptable salt thereof;
wherein: [0147] q is chosen from 0, 1, 2, and 3; [0148] R.sup.22
and R.sup.23 are independently chosen from C.sub.1-4 alkyl,
substituted C.sub.1-4 alkyl, C.sub.1-4 alkoxy, substituted
C.sub.1-4 alkoxy, --NH.sub.2, --NHC(O)R.sup.34, and
--N(R.sup.34).sub.2; or R.sup.22 and R.sup.23 together with the
carbon to which they are bonded form a ring chosen from a C.sub.3-8
cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.3-8
beterocycloalkyl, and substituted C.sub.3-8 heterocycloalkyl ring;
and [0149] each R.sup.24 is independently chosen from hydrogen,
halogen, --OR.sup.7, --CN, --CF.sub.3, .dbd.O, --NO.sub.2,
--COOR.sup.33, C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl,
C.sub.6-10 aryl, substituted C.sub.6-10 aryl, C.sub.3-8 cycloalkyl,
substituted C.sub.3-8 cycloalkyl, C.sub.7-18 arylalkyl, substituted
C.sub.7-18 arylalkyl, C.sub.4-16 cycloalkylalkyl, substituted
C.sub.4-16 cycloalkylalkyl, C.sub.1-8 heteroalkyl, substituted
C.sub.1-8 heteroalkyl, C.sub.5-10 heteroaryl, substituted
C.sub.5-10 heteroaryl, C.sub.3-8 heterocycloalkyl, substituted
C.sub.3-8 heterocycloalkyl, C.sub.6-18 heteroarylalkyl, substituted
C.sub.6-18 heteroarylalkyl, C.sub.4-16 heterocycloalkylalkyl,
substituted C.sub.4-16 heterocycloalkylalkyl, --NH.sub.2,
--NHC(O)R.sup.34, --NHR.sup.34, and --N(R.sup.34).sub.2; wherein:
[0150] R.sup.7 is chosen from hydrogen, C.sub.1-8 alkyl,
substituted C.sub.1-8 alkyl, C.sub.6-10 aryl, substituted
C.sub.6-10 aryl, C.sub.3-8 cycloalkyl, substituted C.sub.3-8
cycloalkyl, --C(O)R.sup.8, --C(O)OR.sup.8, --C(O)N(R.sup.9).sub.2,
--C(O)SR.sup.8, --C(R.sup.9).sub.2OC(O)R.sup.8, and
--C(R.sup.9).sub.2OC(O)OR.sup.8; wherein: [0151] each R.sup.8 is
independently chosen from C.sub.1-6 alkyl, substituted C.sub.1-6
alkyl, C.sub.6-8 aryl, substituted C.sub.6-8 aryl, C.sub.3-8
cycloalkyl, substituted C.sub.3-8 cycloalkyl, C.sub.1-6
heteroalkyl, substituted C.sub.1-6 heteroalkyl, C.sub.5-8
heteroaryl, substituted C.sub.5-8 heteroaryl, C.sub.3-8
heterocycloalkyl, and substituted C.sub.3-8 heterocycloalkyl;
[0152] each R.sup.9 is independently chosen from hydrogen,
C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl, C.sub.6-8 aryl,
substituted C.sub.6-8 aryl, C.sub.3-8 cycloalkyl, substituted
C.sub.3-8 cycloalkyl, and --COOR.sup.35; wherein R.sup.35 is chosen
from hydrogen and C.sub.1-8 alkyl; [0153] R.sup.33 is chosen from
hydrogen and C.sub.1-4 alkyl; [0154] each R.sup.34 is independently
chosen from hydrogen, C.sub.1-8 alkyl, substituted C.sub.1-8 alkyl,
C.sub.1-8 alkoxy, substituted C.sub.1-8 alkoxy, C.sub.6-10 aryl,
substituted C.sub.6-10 aryl, C.sub.6-10 aryloxy, substituted
C.sub.6-10 aryloxy, C.sub.3-8 cycloalkyl, substituted C.sub.3-8
cycloalkyl, C.sub.3-8 cycloalkoxy, substituted C.sub.3-8
cycloalkoxy, C.sub.7-18 arylalkyl, substituted C.sub.7-18
arylalkyl, C.sub.4-16 cycloalkylalkyl, substituted C.sub.4-16
cycloalkylalkyl, C.sub.1-8 heteroalkyl, substituted C.sub.1-8
heteroalkyl, C.sub.5-10 heteroaryl, substituted C.sub.5-10
heteroaryl, C.sub.3-8 heterocycloalkyl, substituted C.sub.3-8
heterocycloalkyl, C.sub.6-18 heteroarylalkyl, substituted
C.sub.6-18 heteroarylalkyl, C.sub.4-16 heterocycloalkylalkyl, and
substituted C.sub.4-16 heterocycloalkylalkyl; and [0155] with the
proviso that when n is 1 and each of R.sup.22 and R.sup.23 is
methyl; then R.sup.24 is not chosen from OR.sup.7, --COOR.sup.33,
and substituted heteroalkyl.
[0156] In certain embodiments of a compound of Formula (II), each
substituent is independently chosen from halogen, --OH, --CN,
--CF.sub.3, --OCF.sub.3, .dbd.O, --NO.sub.2, C.sub.1-4 alkoxy,
C.sub.1-4 alkyl, --COOR.sup.30, --N(R.sup.31).sub.2, and
--CON(R.sup.32).sub.2; wherein each R.sup.30, R.sup.31, and
R.sup.32 is independently chosen from hydrogen and C.sub.1-4 alkyl.
In certain embodiments of a compound of Formula (II), each
substituent is chosen from C.sub.1-4 alkyl, C.sub.1-4 alkoxy, --OH,
and --NH.sub.2.
[0157] In certain embodiments of a compound of Formula (II), q is
chosen from 0, 1, and 2. In certain embodiments of a compound of
Formula (II), q is 0, q is 1, q is 2, and in certain embodiments, q
is 3.
[0158] In certain embodiments of a compound of Formula (II),
R.sup.22 and R.sup.23 are independently chosen from C.sub.1-4 alkyl
and C.sub.1-4 alkoxy.
[0159] In certain embodiments of a compound of Formula (II), each
of R.sup.22 and R.sup.23 is methyl.
[0160] In certain embodiments of a compound of Formula (II), each
R.sup.24 is independently chosen from hydrogen, halogen, --OH,
--CN, --CF.sub.3, .dbd.O, --NO.sub.2, C.sub.1-6 alkoxy, C.sub.1-6
alkyl, --COOR.sup.33, and --N(R.sup.34).sub.2; wherein R.sup.33 is
chosen from hydrogen and C.sub.1-3 alkyl; and each R.sup.34 is
independently chosen from hydrogen and C.sub.1-3 alkyl.
[0161] In certain embodiments of a compound of Formula (II), each
R.sup.24 is chosen from hydrogen, C.sub.1-4 alkyl, and C.sub.1-4
alkoxy. In certain embodiments of a compound of Formula (II), each
R.sup.24 is hydrogen.
[0162] In certain embodiments of a compound of Formula (II), the
stereochemistry of the carbon atom to which R.sup.24 is bonded is
of the (S)-configuration.
[0163] In certain embodiments of a compound of Formula (II), the
stereochemistry of the carbon atom to which R.sup.24 is bonded is
of the (R)-configuration.
[0164] In certain embodiments of a compound of Formula (II), q is
chosen from 0, 1, and 2; each R.sup.24 is chosen from hydrogen and
C.sub.1-4 alkyl; and each of R.sup.22 and R.sup.23 is methyl. In
certain embodiments of a compound of Formula (II), the compound is
an embodiment of Formula (II) described herein with the proviso
that when n is 1 and each of R.sup.22 and R.sup.23 is C.sub.1-4
alkyl, then R.sup.24 is not chosen from OR.sup.7, --COOR.sup.33,
and substituted heteroalkyl.
[0165] In certain embodiments of a compound of Formula (II), the
compound is chosen from: [0166]
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoic acid;
[0167] 4-{[3-(acetylamino)propyl]sulfonyloxy-3,3-dimethylbutanoic
acid; [0168]
5-{[3-(acetylamino)propyl]sulfonyloxy}-4,4-dimethylpentanoic acid;
and [0169] a pharmaceutically acceptable salt of any of the
foregoing.
[0170] In certain embodiments of compounds of Formula (I)-(II), a
pharmaceutically acceptable salt is chosen from a sodium salt, a
potassium salt, a lithium salt, an ammonium salt, a calcium salt, a
zinc salt, and a magnesium salt. In certain embodiments of
compounds of Formula (I)-(II), a pharmaceutically acceptable salt
is the hydrochloride salt, and in certain embodiments, the sodium
salt.
[0171] In certain embodiments, compounds of Formula (I)-(II) are
free acids.
Synthesis
[0172] Compounds disclosed herein may be obtained via the synthetic
methods illustrated in Schemes 1-24. Those of ordinary skill in the
art will appreciate that a useful synthetic route to the disclosed
compounds comprises bonding a substituted neopentyl alcohol or
appropriate intermediate thereof bearing a suitable functional
group at the neopentyl position of the promoiety to acamprosate,
i.e. sulfonyl chloride, of acamprosate to form a substituted
neopentyl sulfonyl ester moiety.
[0173] General synthetic methods useful in the synthesis of
compounds described herein are available in the art. Starting
materials useful for preparing compounds and intermediates thereof
are commercially available or can be prepared by well-known
synthetic methods. Other methods for the synthesis of compounds
provided by the present disclosure are either described in the art
or will be readily apparent to the skilled artisan in view of the
references provided herein and may be used to synthesize the
compounds provided by the present disclosure. Accordingly, the
methods presented in the schemes are illustrative rather than
comprehensive or limiting.
[0174] In certain embodiments, and referring to Scheme 1,
commercially available homotaurine 1 can be converted to the
corresponding 3-(N-acetyl) homotaurinate derivative 2 using methods
or variations thereof disclosed in Durlach, et al., U.S. Pat. No.
4,355,043, DE 30 19 350 C2, or Berthelon, et al., U.S. Pat. No.
6,265,437 B1.
##STR00008##
[0175] In certain embodiments, and referring to Scheme 2,
commercially available potassium phthalimide 3 can be reacted with
3-propanesulton 4 in a solvent such as ethanol (EtOH) at a
temperature from about 25.degree. C. to about 80.degree. C. to
provide the corresponding potassium 3-(N-phthalimido)
propylsulfonate 5, using methods or variations thereof described by
Shue, et al., Bioorg. Med. Chem. Lett. 1996, 6, 1709.
##STR00009##
[0176] Referring to Scheme 3 (where Q is NHAc, phthalimido, or
other useful amine precursor, M is a metal salt, and X is halogen),
drugs or suitable precursors of drugs having at least one sulfonic
acid group 6, a suitable sulfonic acid derivative thereof such as a
tetraalkylammonium salt 7, or certain metal salts of sulfonic acids
8 can be reacted with activation agents to provide the
corresponding activated sulfonic acid derivatives, i.e. sulfonyl
chlorides. Useful methods are described in Shue, et al., Bioorg.
Med. Chem. Lett. 1996, 6, 1709; and Korolev, et. al., Synthesis
2003, 3, 383-388. For example, activation of sulfonic acid 6, the
corresponding tetraalkylammonium salt 7, such as the
tetramethylammonium salt of a sulfonic acid derivative, or the
corresponding alkali metal salt 8 (n is 1) can be accomplished by
reaction with an appropriate chlorination agent such as phosphorous
pentachloride (PCl.sub.5), or, alternatively, thionyl chloride
(SOCl.sub.2), sulfuryl chloride (SO.sub.2Cl.sub.2), or cyanuric
chloride (ClCN); in a solvent such as the chlorination agent
itself, dichloromethane (DCM), and the like, optionally in the
presence of a catalyst such as N,N-dimethylformamide (DMF); and at
a temperature from about 0.degree. C. to about 60.degree. C.; to
provide the corresponding sulfonic acid chlorides or sulfonyl
chlorides 9 such as 3-(N-acetyl)propylsulfonyl chloride
(acamprosate chloride) or 3-phthalimido propylsulfonyl
chloride.
##STR00010##
[0177] In certain embodiments, and referring to Scheme 3, certain
activated precursors of drugs having at least one sulfonic acid
group 6, for example, where Q is chlorine and X is chlorine, i.e.
3-chloropropylsulfonyl chloride, are commercially available and can
be used directly as coupling partners for the synthesis of
functionalized prodrug intermediates.
[0178] Masked carboxylate neopentyl sulfonic acid prodrugs,
intermediates, and precursors of any of the foregoing can be
prepared according to general synthetic Schemes 4-24. In general,
activated sulfonic acid intermediates such as sulfonyl chlorides
can be coupled with a functionalized neopentyl alcohol in the
presence of a base and/or a catalyst at a temperature from about
-78.degree. C. to about 65.degree. C. to provide neopentyl sulfonyl
ester prodrugs, intermediates, or precursors. Depending on the
nature of the functional groups of the sulfonyl moiety and/or the
neopentyl alcohol, the intermediates or precursors may be further
derivatized or interconverted to provide the desired prodrugs.
[0179] Examples for preparing functionalized neopentyl promoieties
and appropriately functionalized neopentyl alcohols such as
functionalized 2,2-bis-substituted 3-hydroxy propanoic acid
derivatives, that are useful as coupling partners are shown in the
following schemes.
[0180] Referring to Scheme 4,2,2-bis-substituted 3-hydroxy
propanoic acid derivative 11 (corresponding to n is 0 in Formula
(I)) as a functionalized neopentyl promoiety is provided, where
R.sup.1, R.sup.2, and R.sup.3 are as defined herein. In certain
embodiments, each of R.sup.2 and R.sup.3 is methyl, and R.sup.1 is
alkyl or substituted alkyl, and the starting material is
2,2-dimethyl 3-hydroxypropanoic acid (hydroxypivalic acid) 10. In
certain embodiments, where R.sup.2 and R.sup.3 are independently
chosen from methyl and hydroxymethyl, and R.sup.1 is alkyl or
substituted alkyl, the starting material is
2,2-(bis-hydroxymethyl)propionic acid.
##STR00011##
[0181] Using known synthetic methods, 2,2-bis-substituted 3-hydroxy
propanoic acid derivatives such as 2,2-dimethyl 3-hydroxy propanoic
acid (hydroxypivalic acid), 2,2-(bis-hydroxymethyl)propionic acid,
and the like, can be converted to the corresponding ester
derivative 11 in the presence of an inorganic base such as an
alkali carbonate (e.g., Cs.sub.2CO.sub.3 or K.sub.2CO.sub.3), and
an alkyl halide reagent such as alkyl or benzylic halides (e.g.,
ethyl iodide (EtI), isopropyl bromide (iPrBr), or benzyl bromide
(BnBr)), in an inert solvent such as N,N-dimethylformamide (DMF),
N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMA, DMAc),
dimethylsulfoxide (DMSO), or tetrahydrofuran (THF), at a
temperature from about 0.degree. C. to about 100.degree. C.
[0182] Methods for preparing acyloxyalkyl ester derivatives, and
alkoxy- or aryloxycarbonyloxyoxy ester derivatives 14 of
2,2-bis-substituted 3-hydroxy propanoic acid derivatives 12 are
shown in Scheme 5 where R.sup.2, R.sup.3, R.sup.5, and R.sup.6 are
as defined herein, X is halogen, and Y is oxygen or a bond. In
certain embodiments, where each of R.sup.2 and R.sup.3 is methyl,
R.sup.5 is ethyl, and R.sup.6 is methyl; the starting materials are
2,2-dimethyl 3-hydroxy propanoic acid (hydroxypivalic acid) and
rac-1-chloroethyl ethyl carbonate. Unsubstituted and substituted
1-halogenoalkyl carboxylates, or 1-halogenoalkyl alkyl- or
aryl-carbonates are either commercially available or can be
prepared from commercially available starting materials adapting
procedures or variations thereof according to Harada, et al.,
Synth. Commun. 1994, 24, 767-772; Davidsen, et al., J. Med. Chem.
1994, 37, 4423-4429; Jasys, EP 0 061 274 B1; and Wheeler, et al.,
J. Med. Chem. 1979, 22, 657-661, or other methods known in the art.
Acyloxyalkyl ester derivatives or alkoxy- and
aryloxy-carbonyloxyoxy ester derivative 14 can be obtained by
reacting 2,2-bis-substituted 3-hydroxypropionic acid derivative 12
with a substituted 1-halogenoalkyl carboxylate or a 1-halogenoalkyl
alkyl- or aryl-carbonate 13 in the presence of a tertiary organic
base such as triethylamine (Et.sub.3N, TEA), diethylisopropylamine
(DIEA, Hunigs-base), or NMM (N-methylmorpholine); or an amidine
base such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or
1,5-diazabicyclo(4.3.0)non-5-ene (DBN); either in neat form or in
an organic solvent such as 1,2-dichloroethane (DCE), at a
temperature from about 0.degree. C. to about 100.degree. C.
##STR00012##
[0183] Alternatively, 2,2-bis-substituted 3-hydroxy propanoic acid
derivatives can be prepared according to Scheme 6, where R.sup.1,
R.sup.2, and R.sup.3 are defined herein and Y is oxygen or a bond.
In certain embodiments, each of R.sup.2 and R.sup.3 is methyl;
R.sup.1 is 3-pyridylmethyl (nicotinyl) or 2-(morpholin-4-yl)ethyl
(mofetil); the starting material is 2,2-dimethyl 3-hydroxy
propanoic acid (hydroxypivalic acid) 15; and Y is oxygen.
##STR00013##
[0184] For example, referring to Scheme 6, protection of
hydroxypivalic acid 15 with mixed trialkyl- or mixed
trialkylarylchlorosilanes such as tert-butyl
dimethylsilylchlorosilane (TBDMSCI), triisopropylchlorosilane
(TIPSCI), tert-butyldiphenylsilyl chlorosilane (TBDPSCI), and the
like, in an inert solvent such as dichloromethane (DCM),
tetrahydrofuran (THF), or N,N-dimethylformamide (DMF), in the
presence of an organic base such as imidazole or triethylamine
(Et.sub.3N, TEA), and optionally a catalytic amount of a
nucleophilic catalyst such as 4-(N,N-dimethyl)aminopyridine (DMAP),
at a temperature from about 0.degree. C. to about 60.degree. C.,
provides the corresponding 3-trialklyl- or mixed 3-alkylarylsiloxy
2,2-dimethyl propanoic acid intermediates. Other methods for the
selective introduction and removal of protecting groups and
alternative protection strategies are known in the art.
[0185] Functionalized carboxylic acid derivatives such as
carboxylic acid esters or carboxamides of protected 3-trialklyl- or
mixed 3-alkylarylsiloxy 2,2-bis-substituted propanoic acids can be
obtained through an activation/coupling sequence. For example,
3-trialklyl- or mixed 3-alkylarylsiloxy 2,2-bis-substituted
propanoic acids such as 2,2-dimethyl 3-(tert-butyldimethylsilyloxy)
propanoic acid can be contacted with an activation agent such as a
dehydration agent, e.g., N,N'-dicyclohexylcarbodiimide (DCC); in an
inert solvent such as dichloromethane (DCM), acetonitrile (MeCN),
and the like; in the presence of an additive such as a nucleophilic
acylation catalyst, e.g. 4-(N,N-dimethyamino)pyridine (DMAP); at a
temperature from about 0.degree. C. to about 60.degree. C. The
activated intermediate of the 3-trialklyl- or mixed
3-alkylarylsiloxy 2,2-dimethyl propanoic acid, such as 2,2-dimethyl
3-(tert-butyldimethylsilyloxy)propanoic acid can then be reacted in
the same solvent with a functionalized alcohol such as
2-(morpholin-4-yl)ethanol or 3-pyridylmethanol, to provide the
corresponding alkyl-, aryl-, 3-trialklyl-, or mixed
3-alkylarylsiloxy 2,2-bis-substituted propanoate.
[0186] Reaction of alkyl or aryl 2,2-dialkyl 3-trialkylsilyoxy
propanoates with reagents capable of selectively cleaving the
3-trialkyl or mixed alkylarylsilyl protecting group provide alkyl-
or aryl-2,2-dialkyl 3-hydroxy propanoate 16 that is useful
neopentyl alcohol promoieties and/or coupling partners. For
example, trialkylsilyl or mixed alkylarylsilyl-protected
derivatives can be selectively cleaved using fluoride-containing
agents such as tetrabutylammonium fluoride (TBAF), potassium
fluoride (KF), ammonium fluoride (H.sub.4NF), and hydrogen fluoride
(HF); or using hydrogen fluoride complexes with organic bases such
as triethylamine trihydrofluoride (Et.sub.3N.3HF) or pyridinium
hydrofluoride; in an inert solvent such as tetrahydrofuran (THF);
at a temperature from about 0.degree. C. to about 100.degree. C. to
provide the corresponding desilylated alkyl 2,2-dialkyl 3-hydroxy
propanoate 16.
[0187] As shown in Scheme 7, heteroatom-protected intermediate 18
can be synthesized from an appropriately functionalized 3-hydroxy
propanoic acid derivative such as
2-amino-3-hydroxy-2-methylpropanoic acid 17. Standard
esterification methods, e.g., anhydrous methanol (MeOH) in the
presence of a catalytic amount of an acidic catalyst such as
thionyl chloride (SOCl.sub.2), sulfuryl chloride
(SO.sub.2Cl.sub.2), concentrated sulfuric acid (H.sub.2SO.sub.4),
or trimethylsilyl chloride (TMSCl); or a sulfonic acid derivative
such aspara-toluene sulfonic acid (TsOH) or camphor sulfonic acid
(CSA); at a temperature from about 0.degree. C. to about
100.degree. C. can be used to provide the corresponding protected
methyl ester. As shown in Scheme 7, Step 2, methyl
2-amino-3-hydroxy-2-methylpropanate can be reacted with
di-tert-butylpyrocarbonate (Boc.sub.2O) in the presence of a base
to provide the corresponding N-Boc protected methyl
2-amino-3-hydroxy-2-methylpropanate 18. Examples of useful solvents
for the reaction shown in Scheme 7, step 2, include a mixture of a
1N aqueous solution of sodium hydroxide (NaOH) and 1,4-dioxane, a
saturated aqueous solution of sodium bicarbonate (NaHCO.sub.3) with
acetonitrile as a co-solvent, dichloromethane (DCM), and a tertiary
organic base, optionally in the presence of a catalyst. Examples of
useful tertiary organic bases include triethylamine (TEA) and a
catalytic amount of 4-(N,N-dimethylamino)pyridine (DMAP).
##STR00014##
[0188] Scheme 8 shows the synthesis of alkyl- or aryl-2,2-alkoxy
3-hydroxy propanoate 20 as a functionalized neopentyl promoiety
where R.sup.1 is as defined herein and R.sup.c and R.sup.d are
independently alkyl or R.sup.c and R.sup.d are linked by an alkyl
to form a heteroalkyl ring. In certain embodiments where each of
R.sup.c and R.sup.b is ethyl (Et), and R.sup.1 is ethyl (Et) or
benzyl (Bn), the starting material is the corresponding acrylic
acid derivative 19. The carbon-carbon double bond of an acrylic
acid ester such as an ethyl acrylate or benzyl acrylate can be
dihydroxylated to obtain the corresponding alkyl glycerate using
oxidation agents such as potassium permanganate (KMnO.sub.4) in a
solvent such as acetone and water, at a temperature from about
-78.degree. C. to about 60.degree. C. Methods for the oxidative
transformation of alkenes into vicinal diols are known in the
art.
##STR00015##
[0189] The primary hydroxyl group of an alkyl glycerate can be
selectively protected by reacting the alkyl glycerate with a bulky
trialkyl chlorosilane such as tert-butyl dimethylsilylchlorosilane
(TBDMSCI), triisopropylchlorosilane (TIPSCI), tert-butyl
diphenylsilylchlorosilane (TBDPSCI), in an inert solvent such as
dichloromethane (DCM), tetrahydrofuran (THF), or
N,N-dimethylformamide (DMF), in the presence of an organic base
such as imidazole or triethylamine (Et.sub.3N, TEA), optionally in
the presence of a catalytic amount of a nucleophilic catalyst such
4-(N,N-dimethyl)aminopyridine (DMAP) at a temperature from about
0.degree. C. to about 60.degree. C.
[0190] Methods for oxidizing secondary hydroxyl groups to oxo
groups, i.e. ketones, are well known. For example, the 2-hydroxyl
group of tris alkylsilyl- or mixed alkyl-arylsilyl-protected alkyl
glycerate can be oxidized to provide the corresponding alkyl 2-oxo
3-silyoxy propanoate using
1,1,1-tris(acetyloxy)-1,1-dihydro-1,2-benziodoxol-3-(1H)-one
(Dess-Martin periodinane) in a inert solvent such as
dichloromethane (DCM) at a temperature from about -20.degree. C. to
about 25.degree. C.
[0191] In certain embodiments of Scheme 8, alkyl 2,2-dialkoxy
3-trialkylsilyoxy propanoates are provided. Formation of ketals
from oxo-compounds, i.e. ketones, is well known. For example, an
alkyl 2-oxo 3-trialkylsilyoxy propanoate can be reacted with an
excess of alcohol such as ethanol (EtOH) or an appropriately
functionalized diol such as ethylene glycol; or with a suitable
transacetalization reagent such as a trisalkyl orthoformate, i.e.
triethyl orthoformate, either in the neat form or in the presence
of an inert solvent and a catalyst such as concentrated sulfuric
acid (H.sub.2SO.sub.4), pyridinium para-toluene sulfonate (PPTS),
para-toluene sulfonate (TsOH), or camphorsulfonic acid (CSA); at a
temperature from about -20.degree. C. to about 100.degree. C.
Alternatively, when alcohols are used, the reaction can be carried
out by azeotropic removal of water generated during the
reaction.
[0192] Reaction of an alkyl 2,2-dialkoxy 3-silyoxy propanoate with
reagents capable of selectively cleaving the 3-silyl protecting
group provide alkyl 2,2-dialkoxy 3-hydroxy propanoate 20 that is a
useful neopentyl alcohol promoiety or coupling partner. For
example, reacting an alkyl 2,2-dialkoxy 3-trialkylsilyoxy
propanoate with an acid in a solvent at a temperature from about
0.degree. C. to about 100.degree. C. provides the corresponding
desilylated alkyl 2,2-dialkoxy 3-hydroxy propanoate 20. Examples of
useful acid and solvent mixtures for the reaction include mixtures
of acetic acid (HOAc), water, and tetrahydrofuran (THF); and
concentrated hydrochloric acid (HCl) in ethanol (EtOH).
Alternatively, fluoride-containing agents can be used.
[0193] As shown in Scheme 9 (wherein n, R.sup.2, R.sup.3, and
R.sup.4 are as defined herein; X is halogen such as chloro; Y is
hydrogen, alkoxy,; and Q is a NHAc or a precursor to an amine), an
activated sulfonic acid derivative such as a sulfonyl chloride of a
drug having at least one sulfonic acid group 21, e.g., acamprosate
chloride, or alternatively, a similarly activated sulfonic acid
derivative of a precursor of a drug having at least one sulfonic
acid group can be reacted with a functionalized and externally
masked neopentyl alcohol 22 to provide externally masked neopentyl
acamprosate prodrugs (neopentyl sulfonyl esters) or precursors or
intermediates to such prodrugs 23. Examples of externally masked
nucleophile 22 include functionalized 2,2-bis-substituted 3-hydroxy
propanoic acid derivatives, such as esters.
##STR00016##
[0194] Referring to Scheme 9, when n is 0, a neopentyl promoiety 22
can be a functionalized 2,2-bis-substituted 3-hydroxy propanoic
acid ester where Y is --OR.sup.1, X is chlorine, Q is N-acetylamino
(NHAc), and R.sup.2, R.sup.3, and R.sup.4 are defined herein, and
the activated sulfonic acid derivative is
3-(N-acetyl)propylsulfonyl chloride (acamprosate chloride) 21.
Neopentyl alcohol 22 can be reacted with 3-(N-acetyl)propylsulfonyl
chloride 21 in a solvent such as dichloromethane (DCM) in the
presence of a base such as triethylamine (Et.sub.3N, TEA),
pyridine, or diisopropyl ethyl amine (iPr.sub.2EtN, DIEA); and a
nucleophilic catalyst such as 4-(N,N-dimethyl)pyridine (DMAP); at a
temperature from about -20.degree. C. to about 25.degree. C. to
provide the corresponding internally masked neopentyl sulfonyl
ester 23.
[0195] When Q is N-acetylamino (NHAc), R.sup.2 and R.sup.3 are
independently chosen from methyl and tert-butoxycarbonylamino
(NHBoc), Y is methoxy, and n is 0 in Scheme 9, as shown in Scheme
10 the corresponding N-unprotected derivative of neopentyl
sulfonylester acamprosate prodrug 25 can be prepared by reacting a
N-Boc-protected neopentyl sulfonyl ester derivative 24 with a
strong acid in an inert solvent such as trifluoroacetic acid in
dichloromethane (DCM) or hydrogen chloride (HCl) in 1,4-dioxane. In
the reaction the tert-butoxycarbonyl (Boc) protecting group can be
cleaved to provide the corresponding unprotected species in either
free amine or in N-protonated form, i.e. ammonium salt, where G is
chosen from NH.sub.2, NH.sub.3.sup.+Cl.sup.-, and
NH.sub.3.sup.+F.sub.3CCO.sub.2.sup.-.
##STR00017##
[0196] As shown in Scheme 11, and also referring to Scheme 9, when
Q is N-acetylamino (NHAc), each of R.sup.2 and R.sup.3 is methyl, Y
is benzoyloxy, i.e., phenylmethoxy, and n is 0; the free acid 27 of
the corresponding benzyl hydroxypivalic acid conjugate 26 can be
obtained by reacting the conjugate with hydrogen in the presence of
a heterogeneous catalyst such as palladium on activated carbon, in
a solvent such as methanol (MeOH), ethanol (EtOH), or ethyl acetate
(EtOAc), at a temperature from about 0.degree. C. to about
50.degree. C. and under a pressure of about 15 psi to about 60
psi.
##STR00018##
[0197] Examples of methods for synthesizing functionalized
neopentyl promoieties, appropriately functionalized neopentyl
alcohols, precursors, or derivatives thereof, such as suitably
functionalized 2,2-bis-substituted .omega.-unsaturated alcohols
that are useful as coupling partners are shown in the following
schemes.
[0198] Scheme 12 (where R.sup.2, R.sup.3, and R.sup.4 are as
defined herein; R.sup.a is hydrogen; R.sup.b is hydrogen, alkyl,
alkoxy, amide, substituted carbonyl or aryl; and A is hydrogen,
hydroxyl, or alkoxy) shows the synthesis of 3,3-bis-substituted
4-hydroxy butanoic acid (corresponding to n is 1 in compound 20)
and 4,4-bis-substituted 5-hydroxy pentanoic acid promoieties
(corresponding to n is 2 in compound 20). The synthetic method
illustrated in Scheme 12 is extendable to homologs such as
5,5-bis-substituted 6-hydroxy hexanoic acids. Conjugates based on
3,3-bis-substituted 4-hydroxy butanoic acid and 4,4-bis-substituted
5-hydroxy pentanoic acid precursor 29 can be derivatized after
coupling to a sulfonyl group of a drug or a precursor of a drug
having at least one sulfonic acid group to provide the
corresponding neopentyl sulfonyl ester prodrug. In certain
embodiments, where each of R.sup.2 and R.sup.3 is methyl, R.sup.4
is hydrogen, and n is either 1 or 2, the starting material 28 can
be chosen from 2,2-dimethyl-4-pentenoic acid, methyl
2,2-dimethyl-4-pentenoic acid, 2,2-dimethyl-4-pentenal, and
2,2-dimethyl-5-hexenoic acid.
##STR00019##
[0199] For example, referring to Scheme 12, in certain embodiments,
A is lower alkoxy such as methoxy, hydroxyl, or hydrogen; each of
R.sup.2 and R.sup.3 is methyl, R.sup.4, each of R.sup.a and R.sup.b
is hydrogen; and n is 1 or 2. Using standard synthetic methods,
2,2-dimethyl-4-pentenoic acid, its lower alkyl ester (A is OH or
O-lower alkyl), or 2,2-dimethyl-5-hexenoic acid can be converted to
the corresponding alcohol 29 by reaction with reducing agents such
as lithium aluminum hydride (LiAlH.sub.4, LAH); in an anhydrous
inert solvent such as tetrahydrofuran (THF) or diethyl ether
(Et.sub.2O); at a temperature from about -78.degree. C. to about
65.degree. C. Alternatively, the reaction can be carried out using
LiBH.sub.4 in an inert solvent such as tetrahydrofuran, at a
temperature from about 0.degree. C. to about 25.degree. C.
Aldehydes 28, e.g., A is H, and n is 1, can be reduced to the
corresponding alcohol 29 using boron hydride reagents such as
alkali borohydrides, e.g., NaBH.sub.4, in an alcohol solvent such
as methanol (MeOH) or ethanol (EtOH).
[0200] Activated sulfonic acid derivatives such as a sulfonyl
chloride of a drug or precursor of a drug having at least one
sulfonic acid group 30, e.g. acamprosate chloride, can be reacted
with a functionalized coupling partner to provide useful
intermediates for preparing externally masked neopentyl sulfonyl
ester prodrugs 32 as disclosed herein. Examples of coupling
partners include functionalized 2,2-bis-substituted
.omega.-unsaturated alcohols 31.
[0201] Referring to Scheme 13 (where n, R.sup.2, R.sup.3, and
R.sup.4 are as defined herein, R.sup.a is hydrogen, R.sup.b is
hydroxy, alkyl, or an aromatic, X is halogen, and Q is an amine
precursor), in certain embodiments where n is 1 or 2, and the
corresponding neopentyl promoieties are functionalized
2,2-bis-substituted .omega.-unsaturated alcohols 31 wherein X is
chlorine, and Q is N-acetylamino (NHAc), and the activated sulfonic
acid derivative is 3-(N-acetyl)propylsulfonyl chloride (acamprosate
chloride) 30. Functionalized 2,2-bis-substituted co-unsaturated
alcohol 31 can be reacted with 3-(N-acetyl)propylsulfonyl chloride
(acamprosate chloride) 30 in a solvent such as dichloromethane
(DCM) in the presence of a base such as triethylamine (Et.sub.3N,
TEA), pyridine, or diisopropyl ethyl amine (iPr.sub.2EtN, DIEA) and
a nucleophilic catalyst such as 4-(N,N-dimethyl)pyridine (DMAP) at
a temperature from about -20.degree. C. to about 25.degree. C. to
provide precursor or intermediate 32 to externally masked neopentyl
sulfonyl esters.
##STR00020##
[0202] As shown in Scheme 14, terminally unsaturated sulfonyl ester
coupling intermediates 33 can then be converted to carboxylic acid
ester sulfonyl ester intermediates 35 such as ester or amide
derivatives. Scheme 14 shows a method for converting the terminal
carbon-carbon double bond to a one carbon shortened ester
derivative. Other methods for the oxidative transformation of
alkenes into aldehydes or carboxylic acid derivatives are described
in the art.
##STR00021##
[0203] In certain embodiments of Scheme 14, Q is N-acetylamino
(NHAc), each of R.sup.2 and R.sup.3 is methyl, R.sup.4 is hydrogen,
each of R.sup.a and R.sup.b is hydrogen, and n is 1 or 2. Oxidative
cleavage of the terminal carbon-carbon double bond of alkene 33 by
ozonolysis using a gaseous mixture of oxygen and ozone
(O.sub.2/O.sub.3) in a solvent such as dichloromethane (DCM) or
DCM/alcohol mixtures, i.e., DCM/MeOH=9:1-5:1, at a temperature of
about -78.degree. C. followed by reductive decomposition of the
intermediate ozonide with a reducing agent such as dimethyl sulfide
(Me.sub.2S), triphenylphosphine (Ph.sub.3P), or tributylphosphine
(Bu.sub.3P), provides intermediate one-carbon shortened aldehyde
derivative 34. Alternatively, aldehyde derivative 34 can be
prepared by oxidation methods using sodium meta-periodate
(NaIO.sub.4)/catalytic osmium tetroxide (OsO.sub.4)
(Lemineux-Johnson reagent) in a mixture of solvents such as
tetrahydrofuran (THF) and water at a temperature from about
0.degree. C. to about 40.degree. C. Other oxidation methods such as
the ruthenium-catalyzed oxidative cleavage of olefins to aldehydes
can also be useful in preparing aldehyde precursors from
unsaturated compounds 33 (Yang, et al., J. Org. Chem. 2001, 66,
4814).
[0204] Aldehyde 34 can be converted to the corresponding carboxylic
acid ester under oxidative reaction conditions to provide
externally masked neopentyl prodrugs that are based on
functionalized (n-1), (n-1)-bis-substituted n-hydroxy alkanoic
acids such as 3,3 bis-substituted 4-hydroxy butanoic acid or
4,4-bis-substituted 5-hydroxy pentanoic acid promoieties. For
example, contacting aldehyde 34 with an oxidant such as
N-iodosuccinimide (NIS); in the presence of an inorganic base such
as alkali carbonate, e.g., K.sub.2CO.sub.3; in a solvent such as
methanol or acetonitrile containing an excess of an alcohol; at a
temperature from about 0.degree. C. to about 40.degree. C. and in
the dark, provides the corresponding carboxylic acid ester as
acamprosate prodrug 35 in a single step. Other oxidant systems that
can be used in this transformation include Oxone.RTM. in an alcohol
solvent, bromine or iodine (Br.sub.2, I.sub.2), N-bromosuccinimide
(NBS)/2,2'-azobis(2-methylpropionitrile (AIBN), pyridinium
dichromate (PDC), and manganese dioxide (MnO.sub.2)/hydrogen
cyanide (HCN).
[0205] When P is oxygen in Scheme 15 (where n, R.sup.1, R.sup.2,
R.sup.3, and R.sup.4 are as defined herein, Q is NHAc or an amine
precursor, R.sup.a is hydrogen (see Scheme 14), aldehyde derivative
36 can be oxidized to the corresponding free carboxylic acid
derivative 37 using standard procedures. For example,
Jones-oxidation of aldehyde 36 with excess chromic acid
(H.sub.2CrO.sub.4) in a solvent such as acetone or a water/acetone
mixture at a temperature from about -10.degree. C. to about
40.degree. C. provides the corresponding carboxylic acid 37. The
oxidant Oxone.RTM. can also be used to oxidize aldehydes to
carboxylic acids in solvents such as N,N-dimethylformamide (DMF)
and at a temperature from about 0.degree. C. to about 25.degree. C.
Other oxidation systems, for example transition metal-based systems
comprising a co-oxidant and an oxidation catalyst can also be used
and are well known in the art.
##STR00022##
[0206] When P in Scheme 15 is .dbd.CHR.sup.b where R.sup.b is
chosen from hydrogen,; and n is 0, 1, or 2, using methods described
by Henry, et al., J. Org. Chem. 1993, 58, 4745; and Travis, et al.,
Org. Lett. 2003, 5, 1031, the corresponding carboxylic acid
intermediate 37 can be prepared by direct oxidation of unsaturated
precursor 36 with oxidation mixtures such as chromic acid
(H.sub.2CrO.sub.4, Jones-reagent) or Oxone.RTM.
(2HKSO.sub.5.KHSO.sub.4.K.sub.2SO.sub.4) in the presence of a
catalytic amount of osmiumtetroxide (OsO.sub.4) in a solvent such
acetone or N,N-dimethylformamide (DMF) at a temperature from about
0.degree. C. to about 40.degree. C. Other methods for effecting
this transformation use systems comprising transition metal
oxidation catalysts based on ruthenium, chromium, or tungsten in
the presence of co-oxidants such as bleach (NaOCl) or sodium
periodate (NalO.sub.4).
[0207] Carboxylic acids are useful precursors for preparing the
corresponding carboxylic acid esters or amides of externally masked
neopentyl prodrugs based on suitably functionalized
3,3-bis-substituted 4-hydroxy butanoic acid or 4,4-bis-substituted
5-hydroxy pentanoic acids. For example, referring to Scheme 15,
carboxylic acids can be activated in situ to provide the
corresponding acid chloride by reacting carboxylic acid 37 with an
activating agent such as oxalyl chloride ((COCl).sub.2) or thionyl
chloride (SOCl.sub.2) in a solvent such as the chlorination agent
itself (neat) or an inert solvent such as dichloromethane (DCM);
optionally in the presence of a catalyst such as a catalytic amount
of N,N-dimethylformamide (DMF) at a temperature from about
0.degree. C. to about 25.degree. C. The acid chloride can then be
quenched with an excess of a functionalized alcohol such as
methanol (MeOH) or benzylic alcohol (BnOH) or other suitable
alcohol or amine in the presence of a base such as pyridine,
triethylamine (Et.sub.3N, TEA), or diisopropylethylamine
(iPr.sub.2EtN, DIEA), in an inert solvent such as dichloromethane
(DCM); at a temperature from about 0.degree. C. to about 25.degree.
C. to provide the corresponding externally masked neopentyl prodrug
38, e.g., an acamprosate prodrug based on a functionalized
3,3-bis-substituted 4-hydroxy butanoic acid or 4,4-bis-substituted
5-hydroxy pentanoic acid.
[0208] Carboxylic acid derivatives may be activated using, for
example, any of the activation agents described herein, and the
activated intermediates can subsequently be coupled to an alcohol
or other functionalized substrate.
[0209] Methods for preparing functionalized 2,2-bis-substituted
.omega.-unsaturated alcohols (functionalized neopentyl alcohols),
or derivatives thereof, useful as coupling partners with an
activated sulfonic acid, such as sulfonyl chlorides of a drug or a
precursor of a drug having at least one sulfonic acid group are
provided in Scheme 16 (where n, R.sup.1, R.sup.2, and R.sup.3 are
as defined herein, R.sup.b is an aromatic, X is hydrogen or alkoxy,
and B is hydroxyl and hydrogen or oxygen). For example, in certain
embodiments of Scheme 16, wherein each of R.sup.1 and R.sup.2 is
methyl; n is 0; R.sup.3 is absent; B is hydroxyl and hydrogen, or
oxygen; the starting materials are either pantolactone or
dihydro-4,4-dimethyl-2,3-furandione; R.sup.b is hydrogen; and X is
hydrogen or methoxy, 3-O-protected 2,2-dimethylpent-4-en-1-ol 43
can be prepared from the starting materials using protocols or
variations thereof according to Blakemore, et al., J. Org. Chem.
2005, 70, 5449; Mandel, et al., Org. Lett. 2004, 6, 4801; Shiina,
et al., Bull. Chem. Soc. Jpn. 2001, 74, 113; Lavallee, et al.,
Tetrahedron Lett. 1986, 27, 679; or Ito et al., Synthesis 1993,
137.
##STR00023## ##STR00024##
[0210] For example, pantolactone 39 where B is hydroxyl and
hydrogen or dihydro-4,4-dimethyl-2,3-furandione 39 where B is
oxygen can be converted to the corresponding
3,3-dimethylbutan-1,2,4-triol 40 by reaction with a reducing agent
such as lithium aluminum hydride (LiAlH.sub.4, LAH) in an anhydrous
inert solvent such as tetrahydrofuran (THF) or diethyl ether
(Et.sub.2O), at a temperature from about -78.degree. C. to about
65.degree. C. Alternatively, excess borane dimethyl sulfide complex
(BH.sub.3.Me.sub.2S) in the presence of a catalytic amount of
sodium borohydride (NaBH.sub.4) in an anhydrous inert solvent such
as tetrahydrofuran (THF), at a temperature from about 0.degree. C.
to about 65.degree. C. can be used for the reaction (Lavallee et
al., Tetrahedron Lett. 1986, 27, 679-682; and Saito et al., Chem.
Lett. 1984, 1389-1392). The reaction proceeds with conservation of
stereochemical integrity (without racemization) when
enantiomerically pure starting materials such as D-pantolactone are
used.
[0211] Using methods described in the literature, triol 40 can be
converted regioselectively to the corresponding 6-membered ring
acetal (benzyliden-type acetal) under thermodynamic conditions
using a suitable aldehyde derivative such as benzaldehyde (X is
hydrogen), anisaldehyde (X is methoxy), benzaldehyde dimethyl
acetal (X is hydrogen), orpara-methoxybenzaldehyde dimethyl acetal
(X is methoxy) in a solvent such as dichloromethane (DCM) or
toluene; and in the presence of a catalyst such as phosphoryl
chloride (POCl.sub.3), camphorsulfonic acid (CSA),
para-toluenesulfonic acid (TsOH), or pyridinium
para-toluenesulfonate (PPTS), at a temperature from about
25.degree. C. to about 110.degree. C. The free hydroxyl group of
the cyclic 1,3-acetal protected triol 41 can be oxidized to the
corresponding aldehyde derivative using standard Swern-oxidation
conditions such as dimethylsulfoxide (DMSO) in the presence of
oxalyl chloride ((COCl).sub.2) and triethylamine (Et.sub.3N, TEA)
in dichloromethane (DCM) at a temperature of about -78.degree. C.
Alternatively, useful oxidants such a sulfur trioxide-pyridine
complex (SO.sub.3.Py) or pyridinium dichromate (PDC) (Cornforth
reagent) in an inert solvent such as dichloromethane (DCM) at a
temperature from about 0.degree. C. to about 25.degree. C. can be
used. Another useful oxidant for this transformation is
1,1,1-tris(acetyloxy)-1,1-dihydro-1,2-benziodoxol-3-(1H)-one
(Dess-Martin periodinane) in an inert solvent such as
dichloromethane (DCM) at a temperature from about -20.degree. C. to
about 25.degree. C.
[0212] Wittig-olefination or methylenation of the aldehyde
derivative with an appropriately functionalized
triphenylphosphoylide or methylenetriphenylphosphorane provides the
corresponding alkene derivative 42. The functionalized phosphoylide
or methylenetriphenylphosphorane can be generated in situ from the
corresponding methyltriphenylphosphonium halide such as bromide, in
a solvent such as tetrahydrofuran (THF) using a base such
n-butyllithium (n-BuLi) or potassium tert-butoxide (KOtBu) at a
temperature from about -78.degree. C. to about 25.degree. C.
Aldehydes and phosphoylides or phosphoranes are reacted in the same
solvent at temperatures from about -78.degree. C. to about
65.degree. C. Mild and non-basic reaction conditions such as using
alternative methylenation reagents in mixtures of solvents such as
dichloromethane (DCM) and tetrahydrofuran (THF) at a temperature
from about 0.degree. C. to about 25.degree. C. can also be used to
convert aldehyde 41 to alkene 42. For example, methylenation
reagents can be generated in situ from zinc dust (Zn), titanium(IV)
halides such as titanium(IV) chloride (TiCl.sub.4), and
dihalomethanes such as dibromomethane (CH.sub.2Br.sub.2) in an
inert organic solvents such tetrahydrofuran (THF) at temperatures
from about -78.degree. C. to about 0.degree. C.
[0213] Using methods known to those skilled in the art,
regioselective reductive ring opening of 1,3-benzylidene acetal 42
with dialkylaluminum hydride reagents such as diisobutylaluminum
hydride (iBu.sub.2AlH, DIBAL(H)) in an inert solvent such as
dichloromethane (DCM) at temperatures from about -78.degree. C. to
about 25.degree. C. provides the corresponding 3-O-protected
2,2-dimethylpent-4-en-1-ol derivative 43. Alternatively,
regioselective reductive acetal ring opening can be accomplished
using reducing agents generated from lithium aluminum hydride
(LiAlH.sub.4, LAH) and aluminum(III) chloride (AlCl.sub.3) in an
inert solvent such as diethyl ether (Et.sub.2O), at temperature
from about 0.degree. C. to about 25.degree. C.
[0214] Alternatively, as shown in Scheme 17 (where PG is a
protecting group and R.sup.b is hydrogen, alkoxycarbonyl, or aryl)
and using procedures or a variations thereof according to Mandel,
et al., Org. Lett. 2004, 6, 4801; and Miyoka, et al., Tetrahedron:
Asymmetry 1995, 6, 587, 3-O-benzylic-protected
2,2-dimethylpent-4-en-1-ol derivatives or
3-O-tert-butyldimethylsilyl protected 2,2-dimethylpent-4-en-1-ol
derivatives can also be prepared from pantolactone 44 using a three
step procedure. In certain embodiments of Scheme 17, PG is a
protecting group such as benzyl, para-methoxybenzyl, or
tert-butyldimethylsilyl (TBDMS), and R.sup.b is hydrogen or
methoxycarbonyl.
##STR00025##
[0215] In certain embodiments, n is 0 and R.sup.1 absent, each of
R.sup.2 and R.sup.3 are methyl, B is hydroxyl and hydrogen and the
starting material 44 is pantolactone. For example, under mildly
basic conditions, the reaction of pantolactone 44 with benzyl
bromide (BnBr) in the presence of silver(I) oxide (Ag.sub.2O) in a
solvent such as N,N-dimethylformamide (DMF) provides the
corresponding O-benzyl-protected pantolactone 45. Other methods for
introducing protecting groups into pantolactone are well known in
the art and include basic conditions prone to partial racemization
if the basicity of the reaction system is not controlled
sufficiently. Examples include cesium carbonate promoted
O-benzylation with benzyl chloride/cesium carbonate in
dimethylformamide (DMF) at room temperature (Dueno et al.,
Tetrahedron Lett. 1999, 40, 1843); allylation with silver
oxide/allyliodide in diethyl ether (Et.sub.2O) (Aurich et al.,
Liebigs Ann. Chem. Recueil 1997, 2, 423); and alkalimetal hydrides,
i.e., NaH or organic bases, i.e., diisopropylethyl amine
[(iPr).sub.2EtN, Hunigs-Base] with various alkylation agents
(Pirrung et al., Synthesis 1995, 4, 458; Hart et al., Hetereocycles
2000, 52(3), 1025; and Gimalova et al., Russ. J. Org. Chem. 2005,
41(8), 1183).The formation of the tetrahydropyranyl ether (Klar et
al., Synthesis 2005, 2, 301) is acid catalyzed
[0216] Using protocols or variations thereof according to O'Brien
et al., Tetrahedron Lett. 2002, 43, 5491-5494; Weinges et al.,
Chem. Ber. 1994, 127, 1305-1309; Johnston et al., J. Chem. Soc.
Perkin Trans. I, 2000, 5, 681-695; Iversen et al, J. Chem. Soc.
Chem. Commun. 1981, 1240-1241; Wessel et al. J. Chem. Soc. Perkin
Trans. I, 1985, 2247-2250; Enders et al., Org. Syntheses 2002, 78,
177-183; and Rai et al., Tetrahedron Lett. 2003, 44, 2267-2269,
O-benzyl or O-para-methoxybenzyl protecting groups can be added to
pantolactone 44 using functionalized acetimidates such as O-benzyl-
or O-para-methoxybenzyl 2,2,2-trichloro acetimidates in the
presence of a catalyst such triflic acid (F.sub.3CSO.sub.3H), a
rare earth triflate such as scandium(III) triflate (Sc(OTf).sub.3),
or others in solvent mixtures such as cyclohexane and
dichloromethane (DCM), toluene, or acetonitrile (MeCN) at
temperatures from about 0.degree. C. to about 40.degree. C. Other
useful catalyst systems include Bronstedt-acids such as
para-toluenesulfonic acid (TsOH), camphorsulphonic acid (CSA),
trifluoroacetic acid (TFA), and Lewis-acids such as trifluoroborane
diethyl ether complex (BF.sub.3. Et.sub.2O), trityl
tetrafluoroborate (TrBF.sub.4), trityl perchlorate (TrClO.sub.4),
trimethylsilyl trifluoromethanesulfonate (TMSOTf), or tin triflates
(Sn(OTf).sub.2, under similar reaction conditions. When enantiopure
starting material such as D-pantolactone is used, the reaction
proceeds with conservation of stereochemical integrity (without
racemization) of the stereogenic center.
[0217] Silicon-based protecting groups, such as mixed tris-alkyl or
alkylaryl silyl-based protecting groups, i.e. tert-butyldimethyl
silyl (tBuMe.sub.2Si, TBDMS), or tert-butyldiphenyl silyl
(tBuPh.sub.2Si, TBDPS), also provide robust protection of the
pantolactone hydroxyl group. For example, the free hydroxyl group
of pantolactone 44 can be protected with tert-butyldimethyl
chlorosilane (tBuMe.sub.2SiCl, TBDMSCI) using an inert solvent such
as dichloromethane (DCM) or N,N-dimethylformamide (DMF) and an
organic base such as imidazole or triethylamine (Et.sub.3N, TEA),
optionally in the presence of additives such as catalytic amounts
of nucleophilic alkylation catalysts such as
4-(N,N-dimethyl)aminopyridine (DMAP) at a temperature from about
0.degree. C. to about 60.degree. C. to provide the corresponding
silyl protected pantolactone 45. When enantiopure starting material
such as D-pantolactone is used, the reaction proceeds with
conservation of stereochemical integrity (without racemization) of
the stereogenic center.
[0218] Reduction of O-benzyl- or O-silyl-protected lactone 45 with
dialkylaluminum hydride reducing reagents such as
diisobutylaluminum hydride [iBu.sub.2AlH, DIBAL(H)] in an inert
solvent such as tetrahydrofuran (THF) at temperatures from about
-78.degree. C. to about 0.degree. C. provides intermediate lactol
or hemiacetal 46 as a mixture of diastereomers or anomers.
[0219] Wittig-olefination of lactol or hemiacetal diastereomer 46
with functionalized triphenylphosphoylides or
methylenetriphenylphosphorane (R.sup.b is H) or methyl
(triphenylphosphoraneylidene)acetate (R.sup.b is CO.sub.2Me)
provides the corresponding (substituted) alkene derivative 47.
Functionalized phosphoylides can be generated in situ from the
corresponding methyltriphenylphosphonium bromide or
(carbomethoxymethyl)triphenylphosphonium bromide in a solvent such
as tetrahydrofuran (THF) in the presence of a base such
n-butyllithium (nBuLi) or potassium tert-butoxide (KOtBu) at
temperatures from about -78.degree. C. to about 25.degree. C.
Lactols 46, phosphoylides, or phosphoranes can then be reacted
either in the same solvent or in a separate solvent such as
1,2-dichloroethane (DCE) at temperatures from about 0.degree. C. to
about 70.degree. C. to provide the corresponding 3-O-benzyl or
3-O-tert-butyldimethylsilyl protected 2,2-dimethylpent-4-en-1-ol
compound 47. Olefination or methylenation of the lactol 46 can also
be accomplished under a variety of Horner-Wadsworth-Emmons
(HWE)-conditions with trimethyl phosphonoacetate (i.e., Banwell et
al., J. Chem. Soc., Perkin Trans. 1, 2002, 22) and an excess of
Tebbe's reagent [Cp.sub.2TiCH.sub.2ClAl(CH.sub.3).sub.2] (Martin et
al., Tetrahedron Lett. 2001, 42, 8373.
[0220] Determination of enantiomeric excess (e.e.) of intermediate
47 can be accomplished by .sup.1H NMR spectroscopy in the presence
of the diamagnetic enantiomerically pure chiral co-solvent
(R)-(-)-2,2,2-trifluoro-1-(9-anthryl)ethanol (Pirkle-alcohol) and
in comparison with .sup.1H NMR spectra of the corresponding racemic
samples under similar conditions or using other analytical method
such as HPLC using chiral stationary phases or enantiopure covalent
derivatization agents such as Mosher's chloride.
[0221] Referring to Scheme 18 (where R.sup.1, R.sup.2, and R.sup.3
are as defined herein, R.sup.b is hydrogen, alkyl, alkoxycarbonyl,
or an aromatic, PG is a protecting group, and X is halogen),
activated sulfonic acid derivatives such as a sulfonyl chlorides of
a drug having at least one sulfonic acid group 48, e.g.
3-chloropropylsulfonyl chloride, can be reacted with a
functionalized protected 2,2-disubstituted pent-4-en-ol derivative
49 to provide masked acamprosate neopentyl sulfonyl ester
intermediates. The intermediates can be converted to the desired
2,4-dihydroxy 3,3-dimethyl butanoic acid- or pantoic acid-based
prodrug. Examples of functionalized protected 2,2-disubstituted
pent-4-en-ol derivative 49 include 3-O-protected
2,2-dimethylpent-4-en-1-ol or derivative thereof.
##STR00026##
[0222] In certain embodiments of Scheme 18, the protected neopentyl
alcohol 49 is a 3-O-protected 2,2-dimethylpent-4-en-1-ol or a
derivative thereof, wherein each of R.sup.2 and R.sup.3 is methyl,
R.sup.b is hydrogen or methoxycarbonyl, PG is benzyl,
para-methoxybenzyl, or tert-butyl dimethylsilyl (TBDMS), X is
chlorine, Q is NHAc, chlorine or 1,3-dioxobenzo[c]azolin-2-yl
(phthalyl)-and the activated sulfonic acid derivative 48 is either
3-chloropropylsulfonyl
chloride,2-[3-(chlorosulfonyl)propyl]benzo[c]azolin-1,3-dione, or
N-[3-(chlorosulfonyl)propyl]acetamide. Functionalized 3-O-protected
2,2-dimethylpent-4-en-1-ol 49 or derivative thereof can be reacted
with 3-chloropropylsulfonyl chloride or
2-[3-(chlorosulfonyl)propyl]benzo[c]azolin-1,3-dione in an inert
solvent such as dichloromethane (DCM) in the presence of a base
such as triethylamine (Et.sub.3N, TEA), pyridine, or
diisopropylethylamine (iPr.sub.2EtN, DIEA) and a nucleophilic
catalyst such as 4-(N,N-dimethyl)pyridine (DMAP) at a temperature
from about -20.degree. C. to about 25.degree. C. to provide the
corresponding neopentyl sulfonyl ester intermediate 50 as a
precursor or intermediate to externally masked neopentyl sulfonyl
ester prodrug 52.
[0223] The terminal alkene group of unsaturated neopentyl sulfonyl
ester intermediate or coupling product 50 can be converted to a
carboxylic acid derivative, such as an ester or amide derivative,
to provide the corresponding functionalized externally masked
neopentyl sulfonyl ester promoiety based on the pantoic acid
scaffold. Methods for converting terminal carbon-carbon double
bonds to ester derivatives are disclosed herein and shown in Scheme
18. Methods for the oxidative transformation of alkenes to
aldehydes or carboxylic acid derivatives are also described in the
art.
[0224] In certain embodiments of Scheme 18, each of R.sup.2 and
R.sup.3 is methyl, R.sup.b is hydrogen or methoxycarbonyl, PG is
benzyl, para-methoxybenzyl, or tert-butyl dimethylsilyl (TBDMD), X
is chlorine, and Q is NHAc, chlorine, or
1,3-dioxobenzo[c]azolin-2-yl (phthalyl). Using synthetic methods
and reaction conditions as previously described the terminal
carbon-carbon double bond of alkene intermediate 50 can be
oxidatively cleaved to provide the corresponding aldehyde. Using
previously described methods and reaction conditions, aldehyde
derivatives can be converted to the corresponding free carboxylic
acid derivative 51 and subsequently converted to the corresponding
carboxylic ester neopentyl intermediate 52.
[0225] Carboxylic acids are useful precursors for preparing the
corresponding carboxylic acid esters of externally masked neopentyl
sulfonyl ester intermediates or prodrugs based on functionalized
(n-1), (n-1)-bis-substituted n-hydroxy alkanoic acids. Methods for
preparing acyloxyalkyl ester derivatives, and alkoxy- or
aryloxy-carbonyloxy ester derivatives 55 of
(n-1),(n-1)-bis-substituted n-hydroxy alkanoic acid derivatives are
shown in Scheme 19 where R.sup.2, R.sup.3, R.sup.4, R.sup.5,
R.sup.6, and PG are as defined herein, X is halogen such as
chlorine or idodine, Y is oxygen or a bond, and Q is NHAc or an
amine precursor. In certain embodiments each of R.sup.2 and R.sup.3
is methyl, R.sup.4 is --OPG with PG is chosen from benzyl,
para-methoxybenzyl, or tert-butyl dimethylsilyl (TBDMS), Y is
oxygen, R.sup.5 is isopropyl, ethyl, cyclohexyl, and R.sup.6 is
hydrogen, methyl or isopropyl.
##STR00027##
[0226] For example, chloromethyl carboxylates can be prepared from
carboxylic acids using commercially available chloromethyl
chlorosulfate in a biphasic mixture of dichloromethane (DCM) and
aqueous sodium bicarbonate in the presence of a phase transfer
catalyst such as tetra-n-butylammonium hydrogensulfate
(nBu.sub.4NHSO.sub.4) at a temperature from about -20.degree. C. to
about 25.degree. C. Alternative reaction conditions employ
chloroiodomethane in the presence of a base such as triethylamaine
(Et.sub.3N, TEA) in a suitable solvent such as
N,N-dimethylformamide. Higher substituted 1-halogenoalkyl
carboxylates can also be obtained from appropriately functionalized
carboxylic acid chlorides and aldehydes in the presence of zinc(II)
chloride either neat or in an inert solvent such as dichloromethane
(DCM) at a temperature from about -20.degree. C. to about
40.degree. C. Furthermore, 1-halogenoalkyl alkyl- or
aryl-carbonates 54 can be prepared from 1-halogenoalkyl
chloroformates such as 1-chloroethyl chloroformate, and an alcohol
in the presence of a base such as pyridine or triethylamine
(Et.sub.3N, TEA) in an inert solvent such as dichloromethane (DCM)
at a temperature from about -20.degree. C. to about 25.degree.
C.
[0227] Acyloxyalkyl ester derivatives or alkoxy- and
aryloxy-carbonyloxyoxy ester derivative 55 can be obtained by
reacting carboxylic acid derivative 53 with a substituted
1-halogenoalkyl carboxylate, or a 1-halogenoalkyl alkyl- or
aryl-carbonate 54 in the presence of a mild base and halide
scavenger such silver(I) carbonate (Ag.sub.2CO.sub.3), silver(I)
oxide (Ag.sub.2O), mercury(II) oxide (HgO), or others, either in an
inert organic solvent such as toluene, or optionally, neat at a
temperature from about 0.degree. C. to about 100.degree. C.
[0228] Pantoic acid derived functionalized neopentyl sulfonyl ester
intermediate 56 can be further modified to provide externally
masked neopentyl sulfonyl ester prodrugs. Scheme 20 shows methods
for converting the functional group Q of an acamprosate precursor
to form a N-acetylamino (NHAc) functionality, where R.sup.1 is as
described herein, PG is a protecting group, and Q is an amine
precursor. Depending on the nature of functional group Q, different
synthetic methods can be used.
##STR00028##
[0229] In certain embodiments of Scheme 20, R.sup.1 is as defined
herein, PG is benzyl orpara-methoxybenzyl, and Q is chlorine or
1,3-dioxobenzo[c]azolin-2-yl (phthalyl). For example, when
functional group Q of intermediate 56 is
1,3-dioxobenzo[c]azolin-2-yl (phthalyl), common synthetic protocols
such as the Ing-Manske exchange procedure can be used to liberate
the free amino group. When Q is 1,3-dioxobenzo[c]azolin-2-yl,
externally masked neopentyl sulfonyl ester intermediate 56 can be
reacted with an excess of hydrazine (H.sub.2NNH.sub.2) in a solvent
such as ethyl acetate (EtOAc) and ethanol (EtOH) or mixtures
thereof at temperatures from about 0.degree. C. to about 60.degree.
C. to provide the corresponding free amine 57. Liberation of the
free amine from phthalimide derivative 57 can also be accomplished
by reacting with sodium sulfide (Na.sub.2S) in aqueous
tetrahydrofuran (THF) or acetone, sodium borohydride
(NaBH.sub.4)/acetic acid, , or using acid or base catalyzed
hydrolysis. Alternative useful and commonly used agents to
deprotect phthalimide protecting groups include methylamine
(MeNH.sub.2) in ethanol (EtOH) or methanol (MeOH) at room
temperature (Motawia et al., Synthesis 1989, 384; and Smith et al.,
J. Am. Chem. Soc. 1992, 114, 3134-3136), and n-butylamine
(nBuNH.sub.2) in methanol (MeOH) at reflux (Durette et al,
Tetrahedron Lett. 1979, 42, 4013-4016).
[0230] Free amine 57 can be converted to the corresponding
protected intermediate 58 by reaction with an acetylation agent
such as acetic anhydride (Ac.sub.2O) or acetyl chloride (AcCl) in a
solvent such as dichloromethane (DCM), tetrahydrofuran (THF), or
pyridine, optionally in the presence of a base such as pyridine,
triethylamine (Et.sub.3N, TEA), or diisopropylethylamine
(iPr.sub.2EtN, DIEA) and/or a nucleophilc acylation catalyst such
4-(N,N-dimethylaminopyridine (DMAP) at temperature from about
-20.degree. C. to about 40.degree. C. to provide corresponding
protected sulfonyl ester intermediate 58.
[0231] In certain embodiments of Scheme 20 where the functional
group Q of intermediate 56 is chlorine, the chloro substituent can
be converted to an N-acetyl functionality (Q is NHAc) using methods
known in the art. For example, intermediate 56 can be reacted with
a reagent capable of providing an azide-nucleophile such as sodium
azide (NaN.sub.3) or tetrabutylammonium azide (nBu.sub.4NN.sub.3),
in a polar non-protic solvent such as anhydrous dimethyl sulfoxide
(DMSO), anhydrous N,N-dimethylformamide (DMF), acetonitrile
(H.sub.3CCN), or mixtures thereof, at a temperature from about
0.degree. C. to about 100.degree. C., to provide the organic
primary azide that can be isolated in pure form. Optionally, the
azide can be used directly in the next step following aqueous
work-up.
[0232] Primary azides (Q is N.sub.3) can be converted to free amine
intermediates that can be isolated in pure form as salts of mineral
acids such as hydrogen chloride (HCl) or organic acids such as
acetic acid (H.sub.3CCO.sub.2H) or trifluoroacetic acid
(F.sub.3CCO.sub.2H), and the like. Appropriate reagents and
reaction conditions for orthogonal and selective deprotection
sequences and functional group interconversions can depend on the
nature of the substituents and determined by those skilled in the
art. In certain embodiments, where Q is azido, an azide-containing
intermediate can be reacted with azide-reducing agents commonly
used in similar chemical transformations. For example, azide
reducing agents such as hydrogen (H.sub.2) in the presence of a
catalyst such a palladium on activated carbon, and a solvent such
as methanol (MeOH), ethanol (EtOH), ethyl acetate (EtOAc), or
mixtures of any of the foregoing under a pressure from about
atmospheric pressure to about 100 psi at a temperature from about
0.degree. C. to about 100.degree. C. can be used.
[0233] Alternatively, the azide functionality can be reduced using
metal salts such as stannous chloride (SnCl.sub.2) in a protic
solvent such as methanol (MeOH), at a temperature from about
0.degree. C. to about 60.degree. C., or, using aryl- or
alkylphosphines such as triphenylphosphine (Ph.sub.3P) or
tributylphosphine (nBu.sub.3P) in a solvent mixture such as
tetrahydrofuran (THF) and water, at a temperature from about
0.degree. C. to about 60.degree. C. The corresponding amine
intermediates 57 are provided in either free amine (Q is NH.sub.2),
or N-protonated, i.e. ammonium form (Q is NH.sub.3+), where the
counter ion is Cl.sup.-, H.sub.3CCO.sub.2.sup.-,
F.sub.3CO.sub.2.sup.-, and the like.
[0234] Free amine 57 obtained from reduction of the azide may be
directly converted to the corresponding N-acetyl derivative 58 by
reacting with an acetylation agent such as acetic anhydride
(Ac.sub.2O) or acetyl chloride (AcCl) in a solvent such as
dichloromethane (DCM), tetrahydrofuran (THF), or pyridine,
optionally in the presence of a base such as pyridine,
triethylamine (Et.sub.3N, TEA), or diisopropylethylamine
(iPr.sub.2EtN, DIEA), and/or a nucleophilc acylation catalyst such
4-(N,N-dimethylaminopyridine (DMAP) at a temperature from about
-20.degree. C. to about 40.degree. C. to provide the corresponding
N-acetylated O-protected neopentyl sulfonyl ester prodrug 58 (Q is
NHAc). In certain embodiments, acetylation agents, bases, and/or
catalysts may be added during or immediately following the
azide-reducing step.
[0235] In certain embodiments where PG is benzyl
orpara-methoxybenzyl and using hydrogenolysis conditions similar to
those described herein, O-protecting groups can be cleaved
simultaneously with the reduction of the azide-functionality to the
corresponding amine to provide the free hydroxyl derivative. In
embodiments where the O-deprotection is complete, selective
N-acetylation with any of the aforementioned acetylation agents
such as acetic anhydride (Ac.sub.2O), acetyl chloride (AcCl) using
similar reagents such as bases and/or catalysts as described herein
may directly provide externally masked neopentyl sulfonyl ester
acamprosate prodrugs 59 that incorporate the pantoic acid scaffold
as a promoiety.
[0236] In certain embodiments of Scheme 20, where PG is benzyl or
para-methoxybenzyl, O-protected externally masked neopentyl
sulfonyl ester derivative 58 can be O-deprotected to generate the
corresponding externally masked neopentyl sulfonyl ester
acamprosate prodrug that incorporates the pantoic acid scaffold as
a promoiety 59. The choice of reagents and reaction conditions will
depend on the nature of the substituents. For example, in
embodiments where PG is benzyl orpara-methoxybenzyl, the reducing
agent can be hydrogen (H.sub.2), the catalyst can be palladium on
activated carbon, and the solvent can be methanol (MeOH), ethanol
(EtOH), or ethyl acetate (EtOAc), and reacted under a pressure from
about atmospheric pressure to about 100 psi at a temperature from
about 0.degree. C. to about 100.degree. C. In certain embodiments,
the addition of a catalytic amount of an organic acid, i.e. acetic
acid (HOAc), i.e mineral acids (HCl), or other acidic reagents may
activate the catalyst system and facilitate the conversion rate for
the transformation.
[0237] In certain embodiments of Scheme 20 where PG is
para-methoxybenzyl, O-protected externally masked neopentyl
sulfonyl ester derivative 58 may be O-deprotected using
orthogonally applicable reagents and reaction conditions to provide
the corresponding externally masked neopentyl sulfonyl ester
prodrug 59. For example, reacting an O-protected externally masked
neopentyl sulfonyl ester acamprosate prodrugs that incorporate the
pantoic acid scaffold with an a excess of
2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in a mixture of
solvents such as dichloromethane (DCM) at a temperature from about
0.degree. C. to about 40.degree. C. provides the corresponding
externally masked neopentyl sulfonyl ester acamprosate prodrug
containing the pantoic acid scaffold as a promoiety 58. Examples of
additional reagents and reaction conditions for this transformation
include ceric ammonium nitrate ((H.sub.4N).sub.2Ce(NO.sub.3).sub.6,
CAN) and solvents such as water, dichloromethane, or
acetonitrile.
[0238] Referring to Scheme 20, selective de-silylation of
O-silyl-protected acamprosate prodrug 58 can be accomplished with
methods well known in the art to provide acamprosate prodrug 59.
For example, trialkylsilyl or mixed alkylarylsilyl-protected
derivative 58 can be selectively deprotected using
fluoride-containing agents such as tetrabutylammonium fluoride
(TBAF), potassium fluoride (KF), ammonium fluoride (H.sub.4NF), or
hydrogen fluoride (HF); or using hydrogen fluoride complexes with
organic bases such as triethylamine trihydrofluoride (Et.sub.3N
3HF) or pyridinium hydrofluoride; in an inert solvent such as
tetrahydrofuran (THF); at a temperature from about 0.degree. C. to
about 100.degree. C. to provide the corresponding desilylated
acamprosate prodrug 59
[0239] Alternative routes for preparing sulfonylester prodrugs,
such as acamprosate prodrugs, from activated sulfonic acid
intermediates are shown in Scheme 21. Functionalized
2,2-bis-substituted .quadrature.-O-protected diol (functionalized
neopentyl alcohols) 62, as functionalized coupling partners to
activated sulfonic acid derivatives provide useful functionalized
and protected neopentyl sulfonyl ester intermediates. The
intermediates can be further modified to provide externally masked
neopentyl sulfonyl ester prodrugs bearing functionalized
(n-1),(n-1)-bis-substituted n-hydroxy alkanoic acid scaffolds in
the promoiety and the parent alkananoic acid on which the prodrugs
are based is either propanoic acid, butanoic acid, or pentanoic
acid. R.sup.1, R.sup.2, R.sup.3, R.sup.4, Q, X, and PG are defined
therein.
##STR00029##
[0240] Referring to Scheme 22 (where n, R.sup.2, R.sup.3, R.sup.4,
Z, and PG are as defined herein), potentially useful starting
materials and methods for preparing functionalized
2,2-bis-substituted .omega.-O-protected diol (functionalized
neopentyl alcohol) 65 are useful as coupling partners with sulfonyl
chlorides are either described in the art or will be readily
apparent to those skilled in the art. Examples of useful protecting
groups (PG) for functionalized 2,2-bis-substituted
.omega.-O-protected diol 65 include benzyl or tris-alkylsilyls and
mixed tris-alkyl-arylsilyls.
##STR00030##
[0241] Activated sulfonic acid derivatives can be reacted with
functionalized 2,2-bis-substituted .omega.-O-protected diol 65 to
provide useful neopentyl sulfonyl ester intermediates. Referring to
Scheme 23, in certain embodiments where each of R.sup.2 and R.sup.3
is methyl, R.sup.4 is hydrogen, each of X and Q is chlorine, PG is
benzyl, functionalized 2,2-bis-substituted (o-O-protected diol 68
is 2,2-dimethyl-5-benzylpentan-1-ol, and the activated sulfonic
acid derivative 67 is 3-chloropropylsulfonyl chloride.
Functionalized 2,2-bis-substituted .omega.-O-protected diol 68 can
be reacted with 3-chloropropylsulfonyl chloride 67 using reaction
conditions as described herein. The reaction can be carried out in
an inert solvent such as dichloromethane (DCM) in the presence of a
base such as triethylamine (Et.sub.3N, TEA), pyridine, or
diisopropylethylamine (iPr.sub.2EtN, DIEA) and a nucleophilic
catalyst such as 4-(N,N-dimethyl)pyridine (DMAP) at a temperature
from about -20.degree. C. to about 25.degree. C. to provide the
corresponding protected neopentyl sulfonyl ester intermediate
69.
##STR00031##
[0242] Protected neopentyl sulfonyl ester intermediate 69 can be
derivatized after coupling to provide the externally masked
neopentyl sulfonyl ester intermediate 70 or if a prodrug then 73.
The chlorine group of intermediate 69 can be converted to the
N-acetylamino (NHAc) using methods described herein followed by
conversion of the protected hydroxyl group in the .omega.-position
of the promoiety precursor to the corresponding carboxylic acid
derivative 71 using methods described herein or known in the
art.
[0243] In certain embodiments of Scheme 23, each of R.sup.2 and
R.sup.3 is methyl, R.sup.4 is hydrogen, m is 2, PG is benzyl, Q is
chlorine, and neopentyl alcohol 68 can be derived from
2,2-dimethylglutaric anhydride. Briefly, neopentyl sulfonyl ester
intermediate 69, where Q is chlorine, can be reacted with an
azide-nucleophile such as sodium azide (NaN.sub.3) or
tetrabutylammonium azide (nBu.sub.4NN.sub.3), in a solvent such as
dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), or
acetonitrile (H.sub.3CCN), at a temperature from about 0.degree. C.
to about 100.degree. C., to provide the organic primary azide.
Primary azides (Q is N.sub.3) can be converted to the corresponding
free amine intermediate that can be isolated in pure form as a salt
of a mineral acid such as hydrogen chloride (HCl) or an organic
acid such as acetic acid (H.sub.3CCO.sub.2H), trifluoroacetic acid
(F.sub.3CCO.sub.2H), and the like. Reactants can include a reducing
agent such as hydrogen (H.sub.2), a catalyst such as palladium on
activated carbon, and a solvent such as methanol (MeOH), ethanol
(EtOH), or ethyl acetate (EtOAc) under a pressure from about
atmospheric pressure to about 100 psi and at a temperature from
about 0.degree. C. to about 100.degree. C. Other useful reducing
agents and conditions include metal salts such as stannous chloride
(SnCl.sub.2) in a protic solvent such as methanol (MeOH), at a
temperature from about 0.degree. C. to about 60.degree. C., or,
alternatively, aryl- or alkyl-phosphines such as triphenylphosphine
(Ph.sub.3P) or tributylphosphine (n-Bu.sub.3P) in a solvent mixture
such as tetrahydrofuran (THF) and water, at a temperature from
about 0.degree. C. to about 60.degree. C.
[0244] Free amines or salts thereof can be directly converted to
the corresponding N-acetyl derivative 70 by reacting with an
acetylation agent such as acetic anhydride (Ac.sub.2O) or acetyl
chloride (AcCl) in a solvent such as dichloromethane (DCM),
tetrahydrofuran (THF), or pyridine, optionally in the presence of
abase such as pyridine, triethylamine (Et.sub.3N, TEA), or
diisopropylethylamine (iPr.sub.2EtN, DIEA), and/or a nucleophilc
acylation catalyst such 4-(N,N-dimethylaminopyridine (DMAP) at a
temperature from about -20.degree. C. to about 40.degree. C. to
provide corresponding N-acetylated O-protected neopentyl sulfonyl
ester intermediate 70 (Q is NHAc). In certain embodiments,
acetylation agents, bases, and/or catalysts may be added directly
during or immediately following the azido reducing step to provide
corresponding N-acetylated O-protected neopentyl sulfonyl ester
intermediate 70 (Q is NHAc).
[0245] In certain embodiments, where PG is benzyl or other benzylic
protecting group, under hydrogenolysis conditions as described
herein, O-protecting groups may be cleaved simultaneously with the
reduction of the azide-functionality to provide the corresponding
free hydroxyl derivative. In embodiments when O-deprotection is
complete, selective N-acetylation with an acetylation agent
provides the N-acetylated O-deprotected neopentyl sulfonyl ester
intermediate 71 that can be further modified to provide neopentyl
sulfonyl ester acamprosate prodrugs that incorporate the (n-1),
(n-1)-bis-substituted n-hydroxy alkanoic acid scaffold as a
promoiety.
[0246] In certain embodiments of Scheme 23, where PG is benzyl or
other benzylic protecting group, N-acetylated O-deprotected
neopentyl sulfonyl ester intermediate 71 can be prepared via
hydrogenolysis of the protecting group using hydrogen (H.sub.2) in
the presence of a catalyst such a palladium on activated carbon in
a solvent such as methanol (MeOH), ethanol (EtOH), or ethyl acetate
(EtOAc) under a pressure from about atmospheric pressure to about
100 psi and at a temperature from about 0.degree. C. to about
100.degree. C. In certain embodiments, the addition of a catalytic
amount of an organic acid such as acetic acid (HOAc), mineral acid
such as hydrochloric acid (HCl), or other acid can be used to
activate the catalyst system and facilitate the conversion rate for
the transformation. In embodiments where PG is a tris-alkyl or
mixed tris alkyl-arylsilyl protecting group, intermediate 70 can be
contacted with a fluoride-containing desilylation agent such as
tetrabutylammonium fluoride (TBAF), potassium fluoride (KF),
ammonium fluoride (H.sub.4NF), hydrogen fluoride (HF), or hydrogen
fluoride complex in an organic base such as triethylamine
trihydrofluoride (Et.sub.3N.3HF) or pyridinium hydrofluoride, in an
inert solvent such as tetrabydrofuran (THF) at a temperature from
about 0.degree. C. to about 100.degree. C. to provide corresponding
desilylated intermediate 71. Depending on the nature of PG, other
reagents and reactions conditions can be used for the
transformation.
[0247] Terminal hydroxyl groups of neopentyl sulfonyl ester
intermediate 71 can be converted to aldehydes or carboxylic acids
as functionalized building blocks for the preparation of externally
masked neopentyl sulfonyl esters prodrugs based on
(n-1),(n-1)-bis-substituted n-hydroxy alkanoic acid scaffolds.
Methods for the oxidative transformation of primary alcohols into
aldehydes or carboxylic acids are known to those skilled in the
art.
[0248] In certain embodiments of Scheme 23, N-acetyl O-deprotected
neopentyl sulfonyl ester intermediate 71 can be oxidized to the
corresponding aldehyde 72 or directly to the corresponding
carboxylic acid derivative 73. Methods for preparing aldehyde 72
include, for example, reaction with
1,1,-tris(acetyloxy)-1,1-dihydro-1,2-benziodoxol-3-(1H)-one
(Dess-Martin periodinane) in an inert solvent such as
dichoromethane (DCM) at a temperature from about -20.degree. C. to
about 25.degree. C. Standard Swern-oxidation conditions such as
dimethylsulfoxide (DMSO) in the presence of oxalyl chloride
((COCl).sub.2) and triethylamine (Et.sub.3N, TEA) in
dichloromethane (DCM) at a temperature of about -78.degree. C. can
also be used. Alternatively, oxidants such a sulfur
trioxide-pyridine complex (SO.sub.3.Py) or pyridinium dichromate
(PDC) (Cornforth reagent) in an inert solvent such as
dichloromethane (DCM) at a temperature from about 0.degree. C. to
about 25.degree. C. can be used. Methods for preparing free
carboxylic acids include oxidation systems comprising transition
metal oxidation catalysts based on ruthenium such as RuCl.sub.3 in
the presence of the co-oxidant sodium periodate (NaIO.sub.4) in a
mixture of acetonitrile/carbontetrachloride/water at a temperature
from about 0.degree. C. to about 40.degree. C. Other useful
ruthenium compounds include RuO.sub.2 and RuO.sub.4 under similar
reaction conditions. In addition, high-valency chromium compounds
such as chromium(VI), manganese(VII) compounds, or peroxytungsten
compounds, optionally in the presence of a co-oxidant such as
bleach (NaOCl) or others, can be used.
[0249] Phosphatases are important metabolic enzymes and are
classified as phosphoric monoester hydrolases (phosphatases, E.C.
3.1.3., phosphoric diester hydrolases (phosphodiesterases, E.C.
3.1.4.), triphosphoric monoester hydrolases (E.C. 3.1.5.),
diphosphoric monoester hydrolases (pyrophosphatases, E.C. 3.1.7.),
and phosphoric ester trimester hydrolases (E.C. 3.1.8). Some of
these enzymes are active in the de-phosporylation reaction of
xenobiotic organophosphorus compounds, including, for example,
alkaline phosphatase, E.C. 3.1.3.1., and others. Phosphate
conjugates of pharmaceutical interest are often monoesters. Enzymes
believed to be able to dephosphorylate phosphate conjugates via
hydrolysis or transphosphorylation include alkaline phosphatases
and acid phosphatases. The de-phosphorylation reactions often
proceed with high catalytic efficiency in vitro and also in vivo to
provide the parent drug. Alkaline phosphatatase is a ubiquitous,
extracellularly bound to membranes, and widely expressed
non-specific esterase of phosphoric monoesters in mammals with an
optimal pH for catalysis at about 8.0 and above. The enzyme is
found particularly in the the gastrointestinal tract, pancreas,
liver, bile, placenta, and osteoplasts.
[0250] Incorporation of a phosphate group to has successfully
overcome numerous drug delivery problems. Phosphate moieties can
either be directly incorporated via a covalent bond to an alcoholic
or phenolic hydroxyl group of a parent drug or prodrug (in form of
a monoester) or via a chemical linker. Generally these
phosphomonoester prodrugs are chemically very stable with long
attractive shelf-lives. Introduction of a phosphate group into a
xenobiotic often constructively influences a multitude of
physiochemical and biological/pharmacokinetic parameters of a drug
or prodrug including increasing the aqueous solubility, improving
the parenteral dosing regime, and modulating specific
pharmacokinetic parameters, i.e., half life (t.sub.max), peak
concentrations (c.sub.max), or concentration time curves
(AUCs).
[0251] Examples for phosphate ester prodrugs of alcohols and
phenols include the gram-positive antibiotic clindamycin phosphate,
the broad-spectrum antifungal fosfluconazole, the orally active
human immunodeficiency virus (HIV) inhibitor fosamprenavir, the
antineoplastic etoposide phosphate, and double prodrugs such as GPI
15715.
[0252] Methods for preparing phosphate conjugates of acamprosate
prodrugs or derivatives thereof, with useful physiochemical,
biological, or pharmacokinetic properties are provided in Scheme
24, where R.sup.1, R.sup.2 are defined herein, Y is oxygen or bond.
For example and referring to Scheme 24, using methods well known in
the art, the secondary hydroxyl group of acamprosate prodrugs 74,
or any other hydroxyl group optionally incorporated in the R.sup.1
and R.sup.2 groups, can be phosphorylated with activated
bis-O-protected phosphoric acid diester derivatives to provide the
corresponding phosphorylated intermediate 75. The protecting groups
of the phosphoric acid moiety are chosen in a way that the
protecting groups in compound 75 can be removed orthogonally
without affecting any of the additional functional groups to
provide the free phosphate conjugate 76.
##STR00032##
[0253] In certain embodiments of Scheme 24, where R.sup.1 and
R.sup.2 are defined herein, Y is oxygen or bond, the free secondary
hydroxyl group of acamprosate prodrug 74 can be reacted with
protected and activated phosphorous acid derivatives such as
commercially available diphenyl chlorophosphate (PhO).sub.2POCl,
dibenzyl chlorophosphate (BnO).sub.2POCl, or di-tert-butyl
chlorophosphate (tBuO).sub.2POCl) in a suitable solvent such as
dichloromethane (DCM) and in the presence of suitable bases such as
triethylamine (Et.sub.3N, TEA), diisopropylethylamine
[(iPr).sub.2EtN, DIEA, Hunigs-base], pyridine, and optionally in
the presence of catalysts such 4-(N,N-dimethylamino)pyridine (DMAP)
at a temperature from about 0.degree. C. to about 40.degree. C.
[0254] Referring to Scheme 24, intermediate 75 can be deprotected
and converted the free phosphate monoesters of acamprosate prodrug
76 with methods known in the art where R.sup.1 and R.sup.2 are
defined herein, Y is oxygen or bond. In certain embodiments, PG is
phenyl and the phenyl groups are removed via hydrogenolysis under a
hydrogen atmosphere format a pressure from about 1 atm to about 100
psi and at a temperature from about 0.degree. C. to about
60.degree. C. employing platinum(IV)-based heterogenous catalysts
such as platinum(IV) oxide Pt(IV)O.sub.2 or hydrates thereof, i.e.
Pt(IV)O.sub.2.H.sub.2O, x.about.1) (Adam's catalysts) in suitable
solvents such as methanol (MeOH), ethanol (EtOH), water, or
mixtures thereof optionally in the presence of a trace amount of an
acidic additive such as an organic acid, i.e. acetic acid (HOAc) or
diluted mineral acid such as one molar (1.0 M) hydrochloric acid
(HCl). If PG in compound 75 is chosen from Bn, then the
heterogenous catalyst can also be palladium on activated carbon in
a solvent such methanol (MeOH), ethyl acetate (EtOAc), mixtures
thereof, or others (Scheme 24). If PG in compound 75 is optionally
chosen from tBu then the protecting groups can be removed by
contacting compounds 75 at temperatures from about 0.degree. C. to
about 40.degree. C. with strong acids such as trifluoroacetic acid
(TFA) in a suitable solvent such as dichloromethane (DCM) or,
optionally, with hydrogen chloride (HCl (in 1,4-dioxane or diethyl
ether (Et.sub.2O).
Pharmaceutical Compositions
[0255] Pharmaceutical compositions provided by the present
disclosure comprise a compound of Formula (I) together with a
suitable amount of one or more pharmaceutically acceptable vehicles
so as to provide a composition for proper administration to a
patient. Examples of suitable pharmaceutical vehicles are known in
the art.
[0256] Pharmaceutical compositions comprising a compound of Formula
(I) may be manufactured by means of conventional mixing,
dissolving, granulating, dragee-making, levigating, emulsifying,
encapsulating, entrapping, or lyophilizing processes.
Pharmaceutical compositions may be formulated in a conventional
manner using one or more physiologically acceptable carriers,
diluents, excipients, or auxiliaries, which facilitate processing
of compounds of Formula (I) or crystalline form thereof and one or
more pharmaceutically acceptable vehicles into formulations that
can be used pharmaceutically. Proper formulation is dependent upon
the route of administration chosen. In certain embodiments, a
pharmaceutical composition comprising a compound of Formula (I) or
crystalline form thereof may be formulated for oral administration,
and in certain embodiments for sustained release oral
administration. Pharmaceutical compositions provided by the present
disclosure may take the form of solutions, suspensions, emulsion,
tablets, pills, pellets, capsules, capsules containing liquids,
powders, sustained-release formulations, suppositories, emulsions,
aerosols, sprays, suspensions, or any other form suitable for
administration to a patient.
[0257] Pharmaceutical compositions provided by the present
disclosure may be formulated in a unit dosage form. A unit dosage
form refers to a physically discrete unit suitable as a unitary
dose for patients undergoing treatment, with each unit containing a
predetermined quantity of at least one compound of Formula (I)
calculated to produce an intended therapeutic effect. A unit dosage
form may be for a single daily dose, for administration 2 times per
day, or one of multiple daily doses, e.g., 3 or more times per day.
When multiple daily doses are used, a unit dosage may be the same
or different for each dose. One or more dosage forms may comprise a
dose, which may be administered to a patient at a single point in
time or during a time interval.
[0258] In certain embodiments, a compound of Formula (I) may be
incorporated into pharmaceutical compositions to be administered
orally. Oral administration of such pharmaceutical compositions may
result in uptake of a compound of Formula (I) throughout the
intestine and entry into the systemic circulation. Such oral
compositions may be prepared in a manner known in the
pharmaceutical art and comprise at least one compound of Formula
(I) and at least one pharmaceutically acceptable vehicle. Oral
pharmaceutical compositions may include a therapeutically effective
amount of at least one compound of Formula (I) and a suitable
amount of a pharmaceutically acceptable vehicle, so as to provide
an appropriate form for administration to a patient.
[0259] Pharmaceutical compositions comprising at least one compound
of Formula (I) may be formulated for immediate release for
parenteral administration, oral administration, or for any other
appropriate route of administration.
[0260] Controlled drug delivery systems may be designed to deliver
a drug in such a way that the drug level is maintained within a
therapeutically effective window and effective and safe blood
levels are maintained for a period as long as the system continues
to deliver the drug at a particular rate. Controlled drug delivery
may produce substantially constant blood levels of a drug over a
period of time as compared to fluctuations observed with immediate
release dosage forms. For some drugs, maintaining a constant blood
and tissue concentration throughout the course of therapy is the
most desirable mode of treatment. Immediate release of drugs may
cause blood levels to peak above the level required to elicit a
desired response, which may waste the drug and may cause or
exacerbate toxic side effects. Controlled drug delivery can result
in optimum therapy, and not only can reduce the frequency of
dosing, but may also reduce the severity of side effects. Examples
of controlled release dosage forms include dissolution controlled
systems, diffusion controlled systems, ion exchange resins,
osmotically controlled systems, erodable matrix systems, pH
independent formulations, gastric retention systems, and the
like.
[0261] In certain embodiments, an oral dosage form provided by the
present disclosure may be a controlled release dosage form.
Controlled delivery technologies can improve the absorption of a
drug in a particular region or regions of the gastrointestinal
tract.
[0262] The appropriate oral dosage form for a particular
pharmaceutical composition provided by the present disclosure may
depend, at least in part, on the gastrointestinal absorption
properties of a compound of Formula (I), the stability of a
compound of Formula (I) in the gastrointestinal tract, the
pharmacokinetics of a compound of Formula (I), and the intended
therapeutic profile. An appropriate controlled release oral dosage
form may be selected for a particular compound of Formula (I). For
example, gastric retention oral dosage forms may be appropriate for
compounds absorbed primarily from the upper gastrointestinal tract,
and sustained release oral dosage forms may be appropriate for
compounds absorbed primarily from the lower gastrointestinal tract.
Certain compounds are absorbed primarily from the small intestine.
In general, compounds traverse the length of the small intestine in
about 3 to 5 hours. For compounds that are not easily absorbed by
the small intestine or that do not dissolve readily, the window for
active agent absorption in the small intestine may be too short to
provide a desired therapeutic effect.
[0263] Gastric retention dosage forms, i.e., dosage forms that are
designed to be retained in the stomach for a prolonged period of
time, may increase the bioavailability of drugs that are most
readily absorbed by the upper gastrointestinal tract. For example,
certain compounds of Formula (I) may exhibit limited colonic
absorption, and be absorbed primarily from the upper
gastrointestinal tract. Thus, dosage forms that release a compound
of Formula (I) in the upper gastrointestinal tract and/or retard
transit of the dosage form through the upper gastrointestinal tract
will tend to enhance the oral bioavailability of the compound of
Formula (I). The residence time of a conventional dosage form in
the stomach is about 1 to about 3 hours. After transiting the
stomach, there is approximately a 3 to 5 hour window of
bioavailability before the dosage form reaches the colon. However,
if the dosage form is retained in the stomach, the drug may be
released before it reaches the small intestine and will enter the
intestine in solution in a state in which it can be more readily
absorbed. Another use of gastric retention dosage forms is to
improve the bioavailability of a drug that is unstable to the basic
conditions of the intestine.
[0264] In certain embodiments, pharmaceutical compositions provided
by the present disclosure may be practiced with dosage forms
adapted to provide sustained release of a compound of Formula (I)
upon oral administration. Sustained release oral dosage forms may
be used to release drugs over a prolonged time period and are
useful when it is desired that a drug or drug form be delivered to
the lower gastrointestinal tract. Sustained release oral dosage
forms include any oral dosage form that maintains therapeutic
concentrations of a drug in a biological fluid such as the plasma,
blood, cerebrospinal fluid, or in a tissue or organ for a prolonged
time period. Sustained release oral dosage forms include
diffusion-controlled systems such as reservoir devices and matrix
devices, dissolution-controlled systems, osmotic systems, and
erosion-controlled systems. Sustained release oral dosage forms and
methods of preparing the same are well known in the art.
[0265] Sustained release oral dosage forms may be in any
appropriate form for oral administration, such as, for example, in
the form of tablets, pills, or granules. Granules can be filled
into capsules, compressed into tablets, or included in a liquid
suspension. Sustained release oral dosage forms may additionally
include an exterior coating to provide, for example, acid
protection, ease of swallowing, flavor, identification, and the
like.
[0266] In certain embodiments, sustained release oral dosage forms
may comprise a therapeutically effective amount of a compound of
Formula (I) and at least one pharmaceutically acceptable vehicle.
In certain embodiments, a sustained release oral dosage form may
comprise less than a therapeutically effective amount of a compound
of Fonnula (I) and a pharmaceutically effective vehicle. Multiple
sustained release oral dosage forms, each dosage form comprising
less than a therapeutically effective amount of a compound of
Formula (I) may be administered at a single time or over a period
of time to provide a therapeutically effective dose or regimen for
treating a disease in a patient. In certain embodiments, a
sustained release oral dosage form comprises more than one compound
of Formula (I).
[0267] Sustained release oral dosage forms provided by the present
disclosure can release a compound of Formula (I) from the dosage
form to facilitate the ability of the compound of Formula (I) to be
absorbed from an appropriate region of the gastrointestinal tract,
for example, in the small intestine or in the colon. In certain
embodiments, sustained release oral dosage forms may release a
compound of Formula (I) from the dosage form over a period of at
least about 4 hours, at least about 8 hours, at least about 12
hours, at least about 16 hours, at least about 20 hours, and in
certain embodiments, at least about 24 hours. In certain
embodiments, sustained release oral dosage forms may release a
compound of Formula (I) from the dosage form in a delivery pattern
corresponding to about 0 wt % to about 20 wt % in about 0 to about
4 hours; about 20 wt % to about 50 wt % in about 0 to about 8
hours; about 55 wt % to about 85 wt % in about 0 to about 14 hours;
and about 80 wt % to about 100 wt % in about 0 to about 24 hours;
where wt % refers to the percent of the total weight of the
compound in the dosage form. In certain embodiments, sustained
release oral dosage forms may release a compound of Formula (I)
from the dosage form in a delivery pattern corresponding to about 0
wt % to about 20 wt % in about 0 to about 4 hours; about 20 wt % to
about 50 wt % in about 0 to about 8 hours; about 55 wt % to about
85 wt % in about 0 to about 14 hours; and about 80 wt % to about
100 wt % in about 0 to about 20 hours. In certain embodiments,
sustained release oral dosage forms may release a compound of
Formula (I) from the dosage form in a delivery pattern
corresponding to about 0 wt % to about 20 wt % in about 0 to about
2 hours; about 20 wt % to about 50 wt % in about 0 to about 4
hours; about 55 wt % to about 85 wt % in about 0 to about 7 hours;
and about 80 wt % to about 100 wt % in about 0 to about 8
hours.
[0268] Sustained release oral dosage forms comprising a compound of
Formula (I) may provide a concentration of the corresponding drug
in the plasma, blood, cerebrospinal fluid, or tissue of a patient
over time, following oral administration to the patient. The
concentration profile of the drug may exhibit an AUC that is
proportional to the dose of the corresponding compound of Formula
(I).
[0269] Regardless of the specific type of controlled release oral
dosage form used, a compound of Formula (I) may be released from an
orally administered dosage form over a sufficient period of time to
provide prolonged therapeutic concentrations of the compound of
Formula (I) in the plasma and/or blood of a patient. Following oral
administration, a dosage form comprising a compound of Formula (I)
may provide a therapeutically effective concentration of the
corresponding drug in the plasma and/or blood of a patient for a
continuous time period of at least about 4 hours, of at least about
8 hours, for at least about 12 hours, for at least about 16 hours,
and in certain embodiments, for at least about 20 hours following
oral administration of the dosage form to the patient. The
continuous time periods during which a therapeutically effective
concentration of the drug is maintained may be the same or
different. The continuous period of time during which a
therapeutically effective plasma concentration of the drug is
maintained may begin shortly after oral administration or following
a time interval.
[0270] An appropriate dosage of a compound of Formula (I) or
pharmaceutical composition comprising a compound of Formula (I) may
be determined according to any one of several well-established
protocols. For example, animal studies such as studies using mice,
rats, dogs, and/or monkeys may be used to determine an appropriate
dose of a pharmaceutical compound. Results from animal studies may
be extrapolated to determine doses for use in other species, such
as for example, humans.
Uses
[0271] Compounds of Formula (I) are prodrugs of acamprosate. Thus,
compounds of Formula (I) may be administered to a patient suffering
from any disease including a disorder, condition, or symptom for
which acamprosate is known or hereafter discovered to be
therapeutically effective. Methods for treating a disease in a
patient provided by the present disclosure comprise administering
to a patient in need of such treatment a therapeutically effective
amount of at least one compound of Formula (I).
[0272] Compounds of Formula (I) or pharmaceutical compositions
thereof may provide therapeutic or prophylactic plasma and/or blood
concentrations of the corresponding drug following oral
administration to a patient. The promoiety(ies) of compounds of
Formula (1) may be cleaved in vivo either chemically and/or
enzymatically to release the parent drug. One or more enzymes
present in the intestinal lumen, intestinal tissue, blood, liver,
brain, or any other suitable tissue of a patient may enzymatically
cleave the promoiety of the administered compounds. For example, a
promoiety of a compound of Formula (I) may be cleaved following
absorption of the compound from the gastrointestinal tract (e g.,
in intestinal tissue, blood, liver, or other suitable tissue of a
mammal). For compounds of Formula (I) the masking promoiety is
first cleaved enzymatically, chemically, or by both mechanisms to
provide a neopentyl promoiety terminated with a nitrogen or oxygen
nucleophile. The structures of the oxygen nucleophile metabolic
intermediates have the structures of Formula (II). The nucleophilic
group can then internally cyclize to release acamprosate.
[0273] In certain embodiments, compounds of Formula (I) may be
actively transported across the intestinal endothelium by
transporters expressed in the gastrointestinal tract including the
small intestine and colon. The drug, e.g., acamprosate, may remain
conjugated to the promoiety during transit across the intestinal
mucosal barrier to prevent or minimize presystemic metabolism. In
certain embodiments, a compound of Formula (I) is essentially not
metabolized to acamprosate within gastrointestinal enterocytes, but
is metabolized to release acamprosate within the systemic
circulation, for example in the intestinal tissue, blood/plasma,
liver, or other suitable tissue of a mammal. In such embodiments,
compounds of Formula (I) may be absorbed into the systemic
circulation from the small and large intestines either by active
transport, passive diffusion, or by both active and passive
processes. For example, a promoiety may be cleaved after absorption
from the gastrointestinal tract, for example, in intestinal tissue,
blood, liver, or other suitable tissue of a mammal.
[0274] Compounds of Formula (I) may be administered in similar
equivalent amounts of acamprosate and using a similar dosing
schedule as described in the art for treatment of a particular
disease. For example, in a human subject weighing about 70 kg,
compounds of Formula (I) may be administered at a dose over time
having an equivalent weight of acamprosate from about 10 mg to
about 10 g per day, and in certain embodiments, an equivalent
weight of acamprosate from about 1 mg to about 3 g per day. A dose
of a compound of Formula (I) taken at any one time can have an
equivalent weight of acamprosate from about 1 mg to about 3 g. An
acamprosate dose may be determined based on several factors,
including, for example, the body weight and/or condition of the
patient being treated, the severity of the disease being treated,
the incidence of side effects, the manner of administration, and
the judgment of the prescribing physician. Dosage ranges may be
determined by methods known to one skilled in the art. In certain
embodiments, compounds of Formula (I) provide a higher oral
bioavailability of acamprosate compared to the oral bioavailability
of acamprosate itself when orally administered at an equivalent
dose and in an equivalent dosage form. Consequently, a lesser
equivalent amount of acamprosate derived from a compound of Formula
(I) may be orally administered to achieve the same therapeutic
effect as that achieved when acamprosate itself is orally
administered.
[0275] Compounds of Formula (I) may be assayed in vitro and in vivo
for the desired therapeutic or prophylactic activity prior to use
in humans. For example, in vitro assays may be used to determine
whether administration of a compound of Formula (I) is a substrate
of a transporter protein, including transporters expressed in the
gastrointestinal tract. Examples of certain assay methods
applicable to analyzing the ability of compounds of Formula (I) to
act as substrates for one or more transporter proteins are
disclosed in Zerangue et al., US 2003/0158254. In vivo assays, for
example using appropriate animal models, may also be used to
determine whether administration of a compound of Formula (I) is
therapeutically effective. Compounds of Formula (I) may also be
demonstrated to be therapeutically effective and safe using animal
model systems.
[0276] In certain embodiments, a therapeutically effective dose of
a compound of Formula (I) may provide therapeutic benefit without
causing substantial toxicity. Toxicity of compounds of Formula (I)
prodrugs, and/or metabolites thereof may be determined using
standard pharmaceutical procedures and may be ascertained by one
skilled in the art. The dose ratio between toxic and therapeutic
effect is the therapeutic index. A dose of a compound of Formula
(I) may be within a range capable of establishing and maintaining a
therapeutically effective circulating plasma and/or blood
concentration of a compound of Formula (I) or acamprosate that
exhibits little or no toxicity.
[0277] Compounds of Formula (I) may be used to treat diseases,
disorders, conditions, and symptoms of any of the foregoing for
which acamprosate is shown to provide therapeutic benefit. Hence,
compounds of Formula (I) be used to treat neurodegenerative
disorders, psychotic disorders, mood disorders, anxiety disorders,
somatoform disorders, movement disorders, substance abuse
disorders, binge eating disorder, cortical spreading depression
related disorders, tinnitus, sleeping disorders, multiple
sclerosis, and pain. The underlying etiology of any of the
foregoing diseases being so treated may have a multiplicity of
origins.
[0278] Further, in certain embodiments, a therapeutically effective
amount of one or more compounds of Formula (I) may be administered
to a patient, such as a human, as a preventative measure against
various diseases or disorders. Thus, a therapeutically effective
amount of one or more compounds of Formula (I) be administered as a
preventative measure to a patient having a predisposition for a
neurodegenerative disorder, a psychotic disorder, a mood disorder,
an anxiety disorder, a somatoform disorder, a movement disorder, a
substance abuse disorder, binge eating disorder, a cortical
spreading depression related disorder, tinnitus, a sleeping
disorder, multiple sclerosis, or pain.
[0279] Substance abuse disorders refer to disorders related to
taking a drug of abuse, to the side effects of a medication, and to
toxin exposure. Drugs of abuse include alcohol, amphetamines,
caffeine, cannabis, cocaine, hallucinogens, inhalants, nicotine,
opioids, phencyclidine, or similarly acting arylcyclohexylamines,
sedatives, hypnotics, and anxiolytics.
[0280] Alcoholism or alcohol dependence is a chronic disorder with
genetic, psychosocial, and environmental causes. Alcoholism refers
to ". . . maladaptive alcohol use with clinically significant
impairment as manifested by at least three of the following within
any one-year period: tolerance; withdrawal; taken in greater
amounts or over longer time course than intended; desire or
unsuccessful attempts to cut down or control use; great deal of
time spent obtaining, using, or recovering from use; social,
occupational, or recreational activities given up or reduced;
continued use despite knowledge of physical or psychological
sequelae." (Diagnostic and Statistical Manual of Mental Disorders,
Fourth Edition, Text Revision, Washington D.C., American
Psychiatric Association, 2000 (DSM-IV)). Alcohol use disorders
include alcohol dependence and alcohol abuse. Screening tests
useful for identifying alcoholism include the Alcohol Dependence
Data Questionnaire, the Michigan Alcohol Screening Test, the
Alcohol Use Disorders Identification Test, and the Paddington
Alcohol Test, and other generally recognized tests for diagnosing
alcohol dependence.
[0281] Treatment for alcoholism generally includes psychological,
social, and pharmacotherapeutic interventions aimed at reducing
alcohol-associated problems and usually involves detoxification and
rehabilitation phases. Medications useful in the pharmacologic
treatment of alcohol dependence include disulfiram and
naltrexone.
[0282] Studies suggest that modulation of mGluR.sup.5 receptors
play a role in substance abuse disorders and that mGluR.sup.5
receptor antagonists such as MPEP may be useful in treating such
conditions including drug abuse disorders.
[0283] Acamprosate has been shown to be effective for maintaining
abstinence from alcohol in patients with alcohol dependence that
are abstinent at the initiation of acamprosate treatment (Scott et
al., CNS Drugs 2005, 19(5), 445-464; and Heilig and Egli,
Pharmacology & Therapeutics 2006, 11, 855-876) and as such is
marketed in the United States for the treatment of alcohol
abstinence as Camprale (Forest Laboratories and Merck KGaA).
Typical acamprosate doses range from about 1-2 gm per day to
achieve a steady-state plasma concentration of about 370-640 ng/mL,
which occurs at about 3-8 hours post-dose (Overman et al., Annals
Pharmacotherapy 2003, 37, 1090-1099; Paille et al., Alcohol. 1995,
30, 239-47; and Pelc et al., Br. Psychiatry 1997, 171, 73-77) with
a recommended dose of Campral.RTM. being two to three 333 mg
tablets taken three times daily.
[0284] The efficacy of compounds of Formula (I) and compositions
thereof for treating alcohol dependency may be assessed using
animal models of alcoholism and using clinical studies. Animal
models of alcoholism are known. Clinical protocols for assessing
the efficacy of a compound of Formula (I) for treating alcoholism
are known.
[0285] The effect of acamprosate on relapse in other substances of
abuse has not been extensively studied; however administration of
100 mg/kg acamprosate for 3 days attenuated relapse-like behavior
in cocaine conditioned mice (Mcgeehan and Olive, Behav Pharmacol
2006, 17(4), 363-7). Studies suggest that modulation of mGluR.sup.5
receptors play a role in substance abuse disorders and that
mGluR.sup.5 receptor antagonists such as MPEP may be useful in
treating such conditions including drug abuse disorders and
nicotine abuse disorders. Therefore, acamprosate may have
applicability in treating other substance abuse disorders,
including narcotic abuse disorders and nicotine abuse
disorders.
[0286] Binge eating disorder is characterized by recurrent episodes
of distressing, uncontrollable eating of excessively large amounts
of food without the inappropriate compensatory weight loss
behaviors of bulimia nervosa or anorexia nervosa (DSM-IV, Fourth
Ed., Text Revision, Washington D.C., American Psychiatric Assoc.,
2000). The pathophysiology of binge eating disorders is unknown.
Binge eating disorder is associated with psychopathology such as
compulsive, impulsive, and affective disorders, medical
comorbidity, especially obesity, impaired quality of life, and
disability. Emotional cues such as anger, sadness, boredom, and
anxiety can trigger binge eating. Impulsive behavior and certain
other emotional problems can be more common in people with binge
eating disorder. Antidepressant medications, including tricyclic
antidepressants, selective serotonin re-uptake inhibitors, as well
as some of certain antidepressants, have shown evidence of some
therapeutic value in binge eating disorder (Bello and Jajnal, Brain
Res Bulletin 2006, 70, 422-429; Buda-Levin et al., Physiology &
Behavior 2005, 86, 176-184; and Han et al., Drug Alcohol Dependence
2007, prepublication no. DAD-3137, 5 pages).
[0287] The efficacy of compounds of acamprosate prodrugs and
compositions for treating binge eating may be assessed using animal
models of binge eating and using clinical studies. Animal models of
binge eating are known. Clinical protocols useful for assessing the
efficacy of an acamprosate prodrug for treating binge eating are
also known.
[0288] In certain embodiments, compounds of Formula (I) can be used
to treat tinnitus. Tinnitus is the perception of sound in the
absence of acoustic stimulation and often involves sound sensations
such as ringing, buzzing, roaring, whistling, or hissing that
cannot be attributed to an external sound source. Tinnitus is a
symptom associated with many forms of hearing loss and can also be
a symptom of other health problems.
[0289] Tinnitus can be caused by hearing loss, loud noise,
medicine, and other health problems such as allergies, head or neck
tumors, cardiovascular disorders such as atherosclerosis, high
blood pressure, turbulent blood flow, malformation of capillaries,
trauma such as excessive exposure to loud noise, long-term use of
certain medications such as salicylates, quinine, cisplatin and
certain types of antibiotics, changes to ear bones such as
otosclerosis, and jaw and neck injuries. In general, insults or
damage to the auditory and somatosensory systems can create an
imbalance between inhibitory and excitatory transmitter actions in
the midbrain, auditory cortex, and brain stem. This imbalance can
cause hyperexcitability of auditory neurons that can lead to the
perception of phantom sounds. For acute tinnitus such as tinnitus
induced by drugs or loud noises, increased spontaneous firing rates
in the auditory nerve fibers have been attributed to reduced levels
of central inhibition, presumably by GABA, in central auditory
structures leading to neural hyperactivity in the inferior
colliculus. Although chronic tinnitus may have a different cause
than acute tinnitus, reduced GABA levels have also been
implicated.
[0290] A recent clinical trial suggests that acamprosate may be
effective in treating tinnitus (Azevedo and Figueiredo, Rev Bras
Otorrinolaringol 2005, 71(5), 618-23).
[0291] Acamprosate prodrugs of Formula (I) can be used to treat
tinnitus, including preventing, reducing, or eliminating tinnitus
and/or the accompanying symptoms of tinnitus in a patient. Treating
tinnitus refers to any indicia of success in prevention, reduction,
elimination, or amelioration of tinnitus, including any objective
or subjective parameter such as abatement, remission, diminishing
of symptoms, prevention, or lessening of tinnitus symptoms or
making the condition more tolerable to the patient, making the
tinnitus less debilitating, or improving a patient's physical or
mental well-being.
[0292] The efficacy of an acamprosate prodrug of Formula (I) for
treating tinnitus can be assessed using animal models of tinnitus
and in clinical results. Methods of evaluating tinnitus in animals
and humans are known. The ability of a compound of Formula (I) to
treat tinnitus in human patients may be assessed using objective
and subjective tests such as those described in Bauer and Brozoski,
Laryngoscope 2006, 116(5), 675-681. An example of a test used in a
clinical context to assess tinnitus treatment outcomes is the
Tinnitus Handicap Inventory.
[0293] Neurodegenerative diseases are characterized by progressive
dysfunction and neuronal death. Neurodegenerative diseases
featuring cell death can be categorized as acute, i.e., stroke,
traumatic brain injury, spinal cord injury, and chronic, i.e.,
amyotrophic lateral sclerosis, Huntington's disease, Parkinson's
disease, and Alzheimer's disease. Although these diseases have
different causes and affect different neuronal populations, they
share similar impairment in intracellular energy metabolism NMDA
receptor and non-NMDA receptor mediated excitotoxic injury results
in neurodegeneration leading to necrotic or apoptotic cell death.
Studies also suggest that mGluR.sup.5 receptor activity is involved
in the etiology of neurodegenerative disorders and that mGluR.sup.5
modulators can be useful in treating movement and cognitive
dysfunction associated with neurodegenerative disorders, as well as
exhibit neuroprotective effects.
[0294] Parkinson's disease is a slowly progressive degenerative
disorder of the nervous system characterized by tremor when muscles
are at rest (resting tremor), slowness of voluntary movements, and
increased muscle tone (rigidity). In Parkinson's disease, nerve
cells in the basal ganglia, e.g., substantia nigra, degenerate, and
thereby reduce the production of dopamine and the number of
connections between nerve cells in the basal ganglia. As a result,
the basal ganglia are unable to smooth muscle movements and
coordinate changes in posture as normal, leading to tremor,
incoordination, and slowed, reduced movement (bradykinesia).
[0295] Modulators of NMDA receptor activity have shown therapeutic
potential in the management of Parkinson's disease, as well as have
mGluR.sup.5 receptor antagonists. Accordingly, acamprosate may be
useful in treating Parkinson's disease.
[0296] Studies suggest that agents that NMDA receptor antagonists
or mGluR.sup.5 receptor antagonists are potentially useful for
treating levodopa-induced dyskinesias such as levodopa-induced
dyskinesias in Parkinson's disease Fabbrini et al., Movement
Disorders 2007, 22(10), 1379-1389; and Mela et al., J
Neurochemistry 2007, 101, 483-497). Accordingly, acamprosate
prodrugs provided by the present disclosure may be useful in
treating a movement disorder such as levodopa-induced dyskinesias
in Parkinson's disease.
[0297] The efficacy of a compound of Formula (I) for treating
Parkinson's disease may be assessed using animal models of
Parkinson's disease and in clinical studies. Animal models of
Parkinson's disease are known. The ability of acamprosate prodrugs
to mitigate against L-dopa induced dyskinesias can be assessed
using animal models and in clinical trials.
[0298] Alzheimer's disease is a progressive loss of mental function
characterized by degeneration of brain tissue. In Alzheimer's
disease, parts of the brain degenerate, destroying nerve cells and
reducing the responsiveness of the maintaining neurons to
neurotransmitters. Abnormalities in brain tissue consist of senile
or neuritic plaques, e.g., clumps of dead nerve cells containing an
abnormal, insoluble protein called amyloid, and neurofibrillary
tangles, twisted strands of insoluble proteins in the nerve
cell.
[0299] Excitotoxic cell death is thought to contribute to neuronal
cell injury and death in Alzheimer's diseases and other
neurodegenerative disorders. Excitotoxicity is due, at least in
part, to excessive acylation of NMDA-type glutamate receptors and
the concomitant excessive Ca.sup.2+ influx through the receptor's
associated ion channel. NMDA receptor antagonists have shown
neuroprotective effects in Alzheimer's disease (Lipton, NeuroRx
2004, 1(1), 101-110). As a modulator of the NMDA receptor,
acamprosate may have similar effects.
[0300] The efficacy of administering a compound of Formula (I) for
treating Alzheimer's disease may be assessed using animal models of
Alzheimer's disease and in clinical studies. Useful animal models
for assessing the efficacy of compounds for treating Alzheimer's
disease are known.
[0301] Huntington's disease is an autosomal dominant
neurodegenerative disorder in which specific cell death occurs in
the neostriatum and cortex. Onset usually occurs during the fourth
or fifth decade of life, with a mean survival at age of onset of 14
to 20 years. Huntington's disease is universally fatal, and there
is no effective treatment. Symptoms include a characteristic
movement disorder (Huntington's chorea), cognitive dysfunction, and
psychiatric symptoms. The disease is caused by a mutation encoding
an abnormal expansion of CAG-encoded polyglutamine repeats in the
protein, huntingtin.
[0302] Neuroprotective effects of NMDA antagonists such as
memantine and ketamine in Huntington's disease have been proposed
(Murman et al., Neurology 1997, 49(1), 153-161; and Kozachuk, US
2004/0102525).
[0303] The efficacy of administering a compound of Formula (I) for
treating Huntington's disease may be assessed using animal models
of Huntington's disease and in clinical studies. Animal models of
Huntington's disease are known.
[0304] Amyotrophic lateral sclerosis (ALS) is a progressive
neurodegenerative disorder characterized by the progressive and
specific loss of motor neurons in the brain, brain stem, and spinal
cord. ALS begins with weakness, often in the hands and less
frequently in the feet that generally progresses up an arm or leg.
Over time, weakness increases and spasticity develops characterized
by muscle twitching and tightening, followed by muscle spasms and
possibly tremors.
[0305] A possible cause of ALS is constitutive opening of the
calcium pore in glutamate responsive AMPA channels secondary to a
failure of RNA editing. Recent work has shown that endogenous
polyamines can block the vulnerability of motor neurons to cell
death due to calcium influx through Ca.sup.2+-permeable AMP
receptors. Acamprosate is believed to have an action at AMPA
receptors similar to that of endogenous polyamines. Accordingly, it
has been proposed that acamprosate may be useful in treating ALS
(Kast and Altschuler, Med Hypotheses 2007, 69(4), 836-837).
[0306] The efficacy of a compound of Formula (I) for treating ALS
may be assessed using animal models of ALS and in clinical studies.
Natural disease models of ALS include mouse models (motor neuron
degeneration, progressive motor neuropathy, and wobbler) and the
hereditary canine spinal muscular atrophy canine model.
Experimentally produced and genetically engineered animal models of
ALS can also useful in assessing therapeutic efficacy.
Specifically, the SODI-G93A mouse model is a recognized model for
ALS. Examples of clinical trial protocols useful in assessing
treatment of ALS are known.
[0307] Multiple sclerosis (MS) is an inflammatory autoimmune
disease of the central nervous system caused by an autoimmune
attack against the isolating axonal myelin sheets of the central
nervous system. Demyelination leads to the breakdown of conduction
and to severe disease with destruction of local axons and
irreversible neuronal cell death. The symptoms of MS are highly
varied with each patient exhibiting a particular pattern of motor,
sensory, and sensory disturbances. MS is typified pathologically by
multiple inflammatory foci, plaques of demyelination, gliosis, and
axonal pathology within the brain and spinal cord, all of which
contribute to the clinical manifestations of neurological
disability. Although the causal events that precipitate MS are not
fully understood, evidence implicates an autoimmune etiology
together with environmental factors and specific genetic
predispositions. Functional impairment, disability, and handicap
are expressed as paralysis, sensory and octintive disturbances,
spasticity, tremor, lack of coordination, and visual impairment.
These symptoms significantly impact the quality of life of the
individual.
[0308] Involvement of ionotropic glutamate receptor function
including the NMDA receptor, AMPA receptor, and kainite receptor
are implicated in the pathology of MS). Compounds that modulate the
NMDA and AMPA/kainite family of glutamate receptors have shown
neuroprotective effects in multiple sclerosis (Killestein et al., J
Neurol Sci 2005, 233, 113-115). As a mediator of ionotropic
glutamate receptors, acamprosate is potentially useful in treating
MS.
[0309] Assessment of MS treatment efficacy in clinical trials can
be accomplished using tools such as the Expanded Disability Status
Scale and the MS Functional Composite as well as magnetic resonance
imaging lesion load, biomarkers, and self-reported quality of
life). Animal models of MS shown to be useful to identify and
validate potential MS therapeutics include experimental
autoimmune/allergic encephalomyelitis (EAE) rodent models that
simulate the clinical and pathological manifestations of MS.
[0310] In certain embodiments, compounds of Formula (I) or
pharmaceutical compositions thereof can be used to treat a
psychotic disorder such as, for example, schizophrenia. Other
psychotic disorders for which acamprosate prodrugs provided by the
present disclosure may be useful include brief psychotic disorder,
delusional disorder, schizoaffective disorder, and schizophreniform
disorder.
[0311] Schizophrenia is a chronic, severe, and disabling brain
disorder that affects about one percent of people worldwide,
including 3.2 million Americans. Schizophrenia encompasses a group
of psychotic disorders characterized by dysfunctions of the
thinking process, such as delusions, hallucinations, and extensive
withdrawal of the patient's interests form other people.
Schizophrenia includes the subtypes of paranoid schizophrenia
characterized by a preoccupation with delusions or auditory
hallucinations, hebephrenic or disorganized schizophrenia
characterized by disorganized speech, disorganized behavior, and
flat or inappropriate emotions; catatonic schizophrenia dominated
by physical symptoms such as immobility, excessive motor activity,
or the assumption of bizarre postures; undifferentiated
schizophrenia characterized by a combination of symptoms
characteristic of the other subtypes; and residual schizophrenia in
which a person is not currently suffering from positive symptoms
but manifests negative and/or cognitive symptoms of schizophrenia
(DSM-IV-TR classifications 295.30 (Paranoid Type), 295.10
(Disorganized Type), 295.20 (Catatonic Type), 295.90
(Undifferentiated Type), and 295.60 (Residual Type) (Diagnostic and
Statistical Manual of Mental Disorders, Fourth Edition, Text
Revision, American Psychiatric Association, 2000). Schizophrenia
includes these and other closely associated psychotic disorders
such as schizophreniform disorder, schizoaffective disorder,
delusional disorder, brief psychotic disorder, shared psychotic
disorder, psychotic disorder due to a general medical condition,
substance-induced psychotic disorder, and unspecified psychotic
disorders (DSM-IV-TR). Schizoaffective disorder is characterized by
symptoms of schizophrenia as well as mood disorders such as major
depression, bipolar mania, or mixed mania, is included as a subtype
of schizophrenia.
[0312] Symptoms of schizophrenia can be classified as positive,
negative, or cognitive. Positive symptoms of schizophrenia include
delusion and hallucination, which can be measured using, for
example, using the Positive and Negative Syndrome Scale (PANSS).
Negative symptoms of schizophrenia include affect blunting,
anergia, alogia and social withdrawal, can be measured for example,
using the Scales for the Assessment of Negative Symptoms (SANS)
(Andreasen, 1983, Scales for the Assessment of Negative Symptoms
(SANS), Iowa City, Iowa). Cognitive symptoms of schizophrenia
include impairment in obtaining, organizing, and using intellectual
knowledge, which can be measured using the Positive and Negative
Syndrome Scale-cognitive subscale (PANSS-cognitive subscale) or by
assessing the ability to perform cognitive tasks such as, for
example, using the Wisconsin Card Sorting Test.
[0313] The glutamatergic system has been implicated in the etiology
and pathophysiology of schizophrenia and modulators of NMDA
receptor activity and mGluR.sup.5 receptor activity such as
acamprosate have been proposed as potential therapeutic agents for
schizophrenia Paz et al., Eur Neuropsychopharmacology 2008,
prepublication no. NEUPSY-10085, 14 pages). Accordingly,
acamprosate and acamprosate prodrugs provided by the present
disclosure may have efficacy in treating the positive, negative,
and/or cognitive symptoms of schizophrenia (Kozachuk, US
2004/0102525; and Fogel, U.S. Pat. No. 6,689,816).
[0314] The efficacy of compounds of Formula (I) and pharmaceutical
compositions of any of the foregoing for treating schizophrenia may
be determined by methods known to those skilled in the art. For
example, negative, positive, and/or cognitive symptom(s) of
schizophrenia may be measured before, during, and/or after treating
the patient. Reduction in such symptom(s) indicates that a
patient's condition has improved. Improvement in the symptoms of
schizophrenia may be assessed using, for example, the Scale for
Assessment of Negative Symptoms (SANS), Positive and Negative
Symptoms Scale (PANSS) and using Cognitive Deficits tests such as
the Wisconsin Card Sorting Test (WCST).
[0315] The efficacy of a compound of Formula (I) and pharmaceutical
compositions of any of the foregoing may be evaluated using animal
models of schizophrenic disorders. For example, conditioned
avoidance response behavior (CAR) and catalepsy tests in rats are
shown to be useful in predicting antipsychotic activity and EPS
effect liability.
[0316] In certain embodiments, compounds of Formula (I) or
pharmaceutical compositions thereof can be used to treat a mood
disorder such as, for example, a bipolar disorder and a depressive
disorder.
Bipolar Disorder
[0317] Bipolar disorder is a psychiatric condition characterized by
periods of extreme mood. The moods can occur on a spectrum ranging
from depression (e.g., persistent feelings of sadness, anxiety,
guilt, anger, isolation, and/or hopelessness, disturbances in sleep
and appetite, fatigue and loss of interest in usually enjoyed
activities, problems concentrating, loneliness, self-loathing,
apathy or indifference, depersonalization, loss of interest in
sexual activity, shyness or social anxiety, irritability, chronic
pain, lack of motivation, and morbid/suicidal ideation) to mania
(e.g., elation, euphoria, irritation, and/or suspicious). Bipolar
disorder is defined and classified in DSM-IV-TR. Bipolar disorder
includes bipolar 1 disorder, bipolar II disorder, cyclothymia, and
bipolar disorder not otherwise specified. Patients afflicted with
this disorder typically alternate between episodes of depression
(depressed mood, hopelessness, anhedonia, varying sleep
disturbances, difficulty in concentration, psychomotor retardation
and often, suicidal ideation) and episodes of mania (grandiosity,
euphoria, racing thoughts, decreased need for sleep, increased
energy, risk taking behavior).
[0318] Inhibitors of glutamate release such as lamotrigine and
riluzole, and NMDA antagonists such as memantine and ketamine are
being investigated for treating bipolar disorder (Zarate et al., Am
J Psychiatry 2004, 161, 171-174; Zarate et al., Biol Psychiatry
2005, 57, 430-432; and Teng and Demetrio, Rev Bras Psiquiatr 2006,
28(3), 251-6).
[0319] Treatment of bipolar disorder can be assessed in clinical
trials using rating scales such as the Montgomery-Asberg Depression
Rating Scale, the Hamilton Depression Scale, the Raskin Depression
Scale, Feiglmer criteria, and/or Clinical Global Impression Scale
Score).
[0320] Depressive disorders include major depressive disorder,
dysthymic disorder, premenstrual dysphoric disorder, minor
depressive disorder, recurrent brief depressive disorder, and
postpsychotic depressive disorder of schizophrenia (DSM IV).
[0321] Studies support the involvement of the glutamatergic system
in the pathophysiology of depression. NMDA receptor antagonists
have shown antidepressant effects in animal models and in clinical
studies. Modulators of mGluR.sup.5 activity have also shown
potential efficacy as antidepressants.
[0322] The efficacy of compounds provided by the present disclosure
for treating depression can be evaluated in animal models of
depression such as the forced swim test, the tail suspension test
and others, and in clinical trials.
[0323] Anxiety is defined and classified in DSM-IV-TR. Anxiety
disorders include panic attack, agoraphobia, panic disorder without
agoraphobia, agoraphobia without history of panic disorder,
specific phobia, social phobia, obsessive-compulsive disorder,
posttraumatic stress disorder, acute stress disorder, generalized
anxiety disorder, anxiety disorder due to a general medical
condition, substance-induced anxiety disorder, and anxiety disorder
not otherwise specified.
[0324] Neurochemical investigations have linked anxiety to
dysfunction in central GABAergic, serotonergic, and noradrenergc
systems. Modulators of mGluR.sup.5 receptors such as the selective
antagonist 2-methyl-6-(phenylethynyl)-pyridine have been shown to
be effective in treating anxiety disorders (Lea and Faden, CNS Drug
Rev 2006, 12(2), 149-66; and Molina-Hernandez et al., Prog
Neuro-Psychopharmacology Biolog Psychiatry 2006, 30, 1129-1135). In
particular, acamprosate has been proposed for the treatment of
anxiety disorders (Fogel, U.S. Pat. No. 6,689,816).
[0325] Useful animal models for assessing treatment of anxiety
include fear-potentiated startle, elevated plus-maze, X-maze test
of anxiety, and the rat social interaction test. Genetic animal
models of anxiety are also known as are other animal models
sensitive to anti-anxiety agents.
[0326] In clinical trials, efficacy can be evaluated using
psychological procedures for inducing experimental anxiety applied
to healthy volunteers and patients with anxiety disorders or by
selecting patients based on the Structured Clinical interview for
DSM-IV Axis 1 Disorders. One or more scales can be used to evaluate
anxiety and the efficacy of treatment including, for example, the
Penn State Worry Questionnaire, the Hamilton Anxiety and Depression
Scales, the Spielberger State-Trait Anxiety Inventory, and the
Liebowitz Social Anxiety Scale.
[0327] In certain embodiments, acamprosate prodrugs provided by the
present disclosure may be useful in treating somatoform disorders
such as somatization disorder, conversion disorder, hypochndriasis,
and body dysmorphic disorder.
[0328] In certain embodiments, movement disorders include
myoclonus, tremor, tics, tardive dyskinesia, movement disorders
associated with Parkinson's disease and Huntington's disease,
progressive suprauclear palsy, Shy-Drager syndrome, tics,
Tourette's syndrome, chorea and athetosis, spasmodic torticollis,
ataxia, restless legs syndrome, and dystonias. Also included in
movement disorders is spasticity.
[0329] Tardive dyskinesia is a neurological disorder caused by the
long-term or high-dose use of dopamine antagonists such as
antipsychotics. Tardive dyskinesia is characterized by repetitive,
involuntary, purposeless movements such as grimacing, tongue
protrusion, lip smacking, puckering and pursing of the lips, and
rapid eye blinking, and can also involve rapid movements of the
arms, legs, and trunk.
[0330] Studies suggest that NMDA receptors are involved in the
dyskinesia observed in animal models of tardive dyskinesia and NMDA
receptor modulators have to some extent been shown to reverse the
effects of neuroleptic induced vacuous chewing movements, an animal
model of tardive dyskinesia. Accordingly, acamprosate has been
proposed for treating tardive dyskinesia and other movement
disorders including tics, Tourette's syndrome, focal dystonias,
blepharospasm, and Meige Syndrome (Fogel, U.S. Pat. No. 5,952,389,
US 2002/0013366, and US 2006/1028802), and in studies on individual
patients has been shown effective in treating tardive dyskinesia,
dystonia, and tic at acamprosate doses from about 1,000 mg/day to
about 2,000 mg/day.
[0331] Efficacy of tardive dyskinesia treatment can be assessed
using animal models.
Spasticity
[0332] Spasticity is an involuntary, velocity-dependent, increased
resistance to stretch. Spasticity is characterized by muscle
hypertonia and displays increased resistance to externally imposed
movement with increasing speed of stretch. Spasticity can be caused
by lack of oxygen to the brain before, during, or after birth
(cerebral palsy); physical trauma (brain or spinal cord injury);
blockage of or bleeding from a blood vessel in the brain (stroke);
certain metabolic diseases; adrenolekodystrophy; phenylketonuria;
neurodegenerative diseases such as Parkinson's disease and
amyotrophic lateral sclerosis; and neurological disorders such as
multiple sclerosis. Spasticity is associated with damage to the
corticospinal tract and is a common complication of neurological
disease. Diseases and conditions in which spasticity may be a
prominent symptom include cerebral palsy, multiple sclerosis,
stroke, head and spinal cord injuries, traumatic brain injury,
anoxia, and neurodegenerative diseases. Patients with spasticity
complain of stiffness, involuntary spasm, and pain. These painful
spasms may be spontaneous or triggered by a minor sensory stimulus,
such as touching the patient.
[0333] Symptoms of spasticity can include hypertonia (increased
muscle tone), clonus (a series of rapid muscle contractions),
exaggerated deep tendon reflexes, muscle spasms, scissoring
(involuntary crossing of the legs), deformities with fixed joints,
stiffness, and/or fatigue caused by trying to force the limbs to
move normally. Other complications include urinary tract
infections, chronic constipation, fever or other systemic
illnesses, and/or pressure sores. The degree of spasticity varies
from mild muscle stiffness to severe, painful, and uncontrollable
muscle spasms. Spasticity may coexist with other conditions but is
distinguished from rigidity (involuntary bidirectional
non-velocity-dependent resistance to movement), clonus
(self-sustaining oscillating movements secondary to hypertonicity),
dystonia (involuntary sustained contractions resulting in twisting
abnormal postures), athetoid movement (involuntary irregular
confluent writhing movements), chorea (involuntary, abrupt, rapid,
irregular, and unsustained movements), ballisms (involuntary
flinging movements of the limbs or body), and tremor (involuntary
rhythmic repetitive oscillations, not self-sustaining). Spasticity
can lead to orthopedic deformity such as hip dislocation,
contractures, or scoliosis; impairment of daily living activities
such as dressing, bathing, and toileting; impairment of mobility
such as inability to walk, roll, or sit; skin breakdown secondary
to positioning difficulties and shearing pressure; pain or abnormal
sensory feedback; poor weight gain secondary to high caloric
expenditure; sleep disturbance; and/or depression secondary to lack
of functional independence.
[0334] Treatment of spasticity includes physical and occupational
therapy such as functional based therapies, rehabilitation,
facilitation such as neurodevelopmental therapy, proprioceptive
neuromuscular facilitation, and sensory integration; biofeedback:
electrical stimulation; and orthoses. Oral medications useful in
treating spasticity include baclofen, benzodiazepines such as
diazepam, dantrolene sodium; imidazolines such as clonidine and
tizanidine; and gabapentin. Intrathecal medications useful in
treating spasticity include baclofen. Chemodenervation with local
anesthetics such as lidocaine and xylocaine; type A botulinum toxin
and type B botulinum toxin; phenol and alcohol injection can also
be useful in treating spasticity. Surgical treatments useful in
treating spasticity include neurosurgery such as selective dorsal
rhizotomy; and orthopedic operations such as contracture release,
tendon or muscle lengthening, tendon transfer, osteotomy, and
arthrodesis.
[0335] Studies suggest that NMDA receptor may play a role in the
activity of muscle relaxants and that NMDA receptor antagonists may
have therapeutic potential in spasticity (Kornhuber and Quack,
Neruosci Lett 1995, 195, 137-139).
[0336] The efficacy of a compound of Formula (I) for the treatment
of spasticity can be assessed using animal models of spasticity and
in clinically relevant studies of spasticity of different
etiologies. The therapeutic activity may be determined without
determining a specific mechanism of action. Animal models of
spasticity are known. For example, animal models of spasticity
include the mutant spastic mouse; the acute/chronic spinally
transected rat and the acute decerebrate rat; primary observation
Irwin Test in the rat; and Rotarod Test in the rat and mouse. Other
animal models include spasticity induced in rats following
transient spinal cord ischemia (; spasticity in mouse models of
multiple sclerosis; and spasticity in rat models of cerebral
palsy.
[0337] The efficacy of compounds of Formula (I) may also be
assessed in humans using double blind placebo-controlled clinical
trials. Clinical trial outcome measures for spasticity include the
Ashworth Scale, the modified Ashworth Scale, muscle stretch
reflexes, presence of clonus and reflex response to noxious
stimuli. Spasticity can be assessed using methods and procedures
known in the art such as a combination of clinical examination,
rating scales such as the Ashworth Scale, the modified Ashworth
scale the spasm frequency scale and the reflex score, biomechanical
studies such as the pendulum test, electrophysiologic studies
including electromyography, and functional measurements such as the
Fugl-Meyer Assessment of Sensorimotor Impairment scale. Other
measures can be used to assess spasticity associated with a
specific disorder such as the Multiple Sclerosis Spasticity
Scale.
[0338] Cortical spreading depression (CSD) is a phenomena believed
to be involved in the pathogenesis of migraine. During the early
phase of CSD, a slow-propagating wave of hyper- then hypo-activity
spreads through the cortex, resulting in hyper- then
hypo-vascularization. This is followed by a prolonged period of
neuronal depression, which is associated with disturbances in nerve
cell metabolism and regional reductions in blood flow. CSD may also
activate trigeminal nerve axons, which then release neuropeptides,
such as substance P, neurokinin A, and CGRP from axon terminals
near the meningeal and other blood vessels that produce an
inflammatory response in the area around the innervated blood
vessels. CSD is also implicated in progressive neuronal injury
following stroke and head trauma; and cerebrovascular disease.
Glutamate release and subsequent NMDA receptor activation have been
implicated in the spread of CSD. NMDA antagonists such as
ifenprodil have been shown effective in preventing CSD in the mouse
entorhinal cortex and the NMDA receptor antagonist MK-801 was
effective in blocking CSD caused by traumatic injury in rat
neocortical brain slices. Accordingly, NMDA receptor antagonists
that inhibit the release of glutamate in the neuron can potentially
prevent CSD and its consequences. For example,
(7-chloro-4-hydroxy-3-(3-phenoxy)phenyl-2-(1H)-quinolone, a high
affinity antagonist at the glycine site of the NMDA receptor
inhibits the initiation and propagation of spreading depression.
Other selective NMDA antagonists and an uncompetitive NMDA receptor
blocker have shown potential for treating cortical spreading
depression migraine (Menniti et al., Neuropharmacology 2000, 39,
1147-1155; and Peeters et al., J Pharmacology and Experimental
Therapeutics 2007, 321(2), 564-572). Accordingly, acamprosate
prodrugs may be useful in treating cortical spreading depression
related disorders such as migraine, cerebral injury, epilepsy, and
cardiovascular disease.
[0339] Efficacy of acamprosate prodrugs provided by the present
disclosure for treating cortical spreading depression can be
assessed using animal models of cortical spreading depression.
[0340] Migraine is a neurological disorder that is characterized by
recurrent attacks of headache, with pain most often occurring on
one side of the head, accompanied by various combinations of
symptoms such as nausea, vomiting, and sensitivity to light, sound,
and odors. The exact mechanism of migraine initiation and progress
is not known. Migraine can occur at any time of day or night, but
occurs most frequently on arising in the morning. Migraine can be
triggered by various factors, such as hormonal changes, stress,
foods, lack of sleep, excessive sleep, or visual, auditory,
olfactory, or somatosensory stimulation. In general, there are four
phases to a migraine: the prodrome, auras, the attack phase, and
postdrome. The prodrome phase is a group of vague symptoms that may
precede a migraine attack by several hours, or even a few days
before a migraine episode. Prodrome symptoms can include
sensitivity to light and sound, changes in appetite, fatigue and
yawning, malaise, mood changes, and food cravings. Auras are
sensory disturbances that occur before the migraine attack in one
in five patients. Positive auras include bright or shimmering light
or shapes at the edge of the field of vision. Other positive aura
experiences are zigzag lines or stars. Negative auras are dark
holes, blind spots, or tunnel vision. Patients may have mixed
positive and negative auras. Other neurologic symptoms that may
occur at the same time as the aura include speech disturbances,
tingling, numbness, or weakness in an arm or leg, perceptual
disturbances such as space or size distortions, and confusion. A
migraine attack usually lasts from 4 to 72 hours and typically
produces throbbing pain on one side of the head, pain worsened by
physical activity, nausea, visual symptoms, facial tingling or
numbness, extreme sensitivity to light and noise, looking pale and
feeling cold, and less commonly tearing and redness in one eye,
swelling of the eyelid, and nasal congestion. During the attack the
pain may migrate from one part of the head to another, and may
radiate down the neck into the shoulder. Scalp tenderness occurs in
the majority of patients during or after an attack. After a
migraine attack, there is usually a postdrome phase, in which
patients may feel exhausted, irritable, and/or be unable to
concentrate. Other types of migraine include menstrual migraines,
ophthalmologic migraine, retinal migraine, basilar migraine,
familial hemiplegic migraine, and status migrainosus.
[0341] It is theorized that persons prone to migraine have a
reduced threshold for neuronal excitability, possibly due to
reduced activity of the inhibitory neurotransmitter y-aminobutyric
acid (GABA). GABA normally inhibits the activity of the
neurotransmitters serotonin (5-HT) and glutamate, both of which
appear to be involved in migraine attacks. The excitatory
neurotransmitter glutamate is implicated in an electrical
phenomenon called cortical spreading depression, which can initiate
a migraine attack, while serotonin is implicated in vascular
changes that occur as the migraine progresses.
[0342] Acamprosate prodrugs provided by the present disclosure or
pharmaceutical composition thereof may be administered to a patient
after initiation of the migraine. For example, a patient may be in
the headache phase of the migraine or the postdrome phase before
the prodrug or pharmaceutical composition is administered.
Alternatively, acamprosate prodrugs provided by the present
disclosure or pharmaceutical composition thereof may be
administered to the patient before the migraine starts, such as
once the patient senses that a migraine is developing or when the
early symptoms of the migraine have begun. Acamprosate prodrugs
provided by the present disclosure may also be administered to a
patient on an ongoing or chronic basis to treat recurrent or
frequent occurrences of migraine episodes.
[0343] Migraine may be diagnosed by determining whether some of a
person's recurrent headaches meet migraine criteria as disclosed
in, for example, see The International Classification of Headache
Disorders, 2nd edition, Headache Classification Committee of the
International Headache Society, Cephalalgia 2004, 24 (suppl 1),
8-160.
[0344] The efficacy of administering at least one compound of
Formula (I) for treating migraine can be assessed using animal
models of migraine and clinical studies. Animal models of migraine
are known. For example, to delineate and assess the effectiveness
of an acamprosate prodrug provided by the present disclosure, the
frequency of migraine attacks, their severity and their
accompanying symptoms may be recorded and measured at baseline, and
at 3 months, and 6 months, etc., following initiation of treatment.
Anti-migraine and cortical-spreading depression activity of
compounds provided by the present disclosure may be determined
using methods known in the art.
[0345] Therapeutic efficacy of a compound of Formula (I) or
pharmaceutical composition of any of the foregoing for treating
migraine may also be determined in various animal models of
neuropathic pain or in clinically relevant studies of different
types of neuropathic pain. The therapeutic activity may be
determined without determining a specific mechanism of action.
Animal models for neuropathic pain are known in the art and
include, but are not limited to, animal models that determine
analgesic activity or compounds that act on the CNS to reduce the
phenomenon of central sensitization that results in pain from
non-painful or non-noxious stimuli. Other animal models are known
in the art, such as hot plate tests, model acute pain and are
useful for determining analgesic properties of compounds that are
effective when painful or noxious stimuli are present. The
progression of migraine is believed to be similar to the progress
of epilepsy because an episodic phenomenon underlies the initiation
of the epileptic episode and, as such, it is believed that epilepsy
animal models may be useful in determining a component of the
therapeutic activity of the pharmaceutical composition.
[0346] Sleeping disorders include primary sleep disorders such as
dysomnias characterized by abnormalities in the amount, quality, or
timing of sleep and parasomnias characterized by abnormal
behavioral or physiological events occurring in association with
sleep, specific sleep stages, or sleep-wake transitions; sleep
disorders related to another mental disorder, sleep disorders due
to a general medical condition; and substance-induced sleep
disorder (DSM-IV). Dysomnias include breathing-related sleep
disorders such as obstructive sleep apnea syndrome characterized by
repeated episodes of upper-airway obstruction during sleep; central
sleep apnea syndrome characterized by episodic cessation of
ventilation during sleep without airway obstruction; and central
alveolar hypoventilation syndrome characterized by impairment in
ventilatory control that results in abnormally low arterial oxygen
levels further worsened by sleep.
[0347] Sleep apnea is a sleep disorder characterized by pauses in
breathing during sleep. Clinically significant levels of sleep
apnea are defined as five or more events of any type per hour of
sleep time. Sleep apnea can be characterized as central,
obstructive, and mixed. In central sleep apnea, breathing is
interrupted by the lack of effort. In obstructive sleep apnea, a
physical block to airflow despite effort results in interrupted
breathing. In mixed sleep apnea, there is a transition from central
to obstructive features during the events. Sleep apnea leads to
interrupted, poor-quality sleep, nocturnal oxygen desaturation, and
a reduction or absence of REM sleep. Sleep apnea may exacerbate or
contribute to cardiovascular disease including coronary heart
disease, hypertension, ventricular hypertrophy and dysfunction,
cardiac arrhythmias, and stroke, by mechanisms such as endothelial
damage and dysfunction, increases in inflammatory mediators,
increases in prothromobitic factors, increased sympathetic
activity, hypoxemia, impaired vagal activity and insulin
resistance. Sleep apnea may also contribute to cognitive
impairment.
[0348] Acamprosate has been shown to improve sleep in patients
being treated for alcohol withdrawal (Staner et al., Alcohol Clin
Exp Res 2006, 30(9), 1492-9) and preliminary studies suggest that
acamprosate at doses of about 1,000 mg/day (333 mg three times per
day) may be effective in treating central and obstructive sleep
apnea (Hedner et al., WO 2007/032720).
[0349] Sleep apnea can be clinically evaluated using
polysomnography or oximetry, and/or using tools such as the Epworth
Sleepiness Scale and the Sleep Apnea Clinical Score and/or using
polysomnographic recording. Animal models of sleep apnea are known
and can be useful in assessing the efficacy of acamprosate prodrugs
for treating sleep apnea.
[0350] Pain includes nociceptive pain caused by injury to bodily
tissues and neuropathic pain caused by abnormalities in nerves,
spinal cord, and/or brain. Pain includes mechanical allodynia,
thermal allodnia, hyperplasia, central pain, peripheral neuropathic
pain, diabetic neuropathy, breakthrough pain, cancer pain,
deafferentation pain, dysesthesia, fibromyalgia syndrome,
hyperpathia, incident pain, movement-related pain, myofacial pain,
and paresthesia. Pain can be acute or chronic.
[0351] Studies demonstrate the involvement of mGluR.sup.5 receptors
in nociceptive processes and that modulation of mGluR.sup.5
receptor activity can be useful in treating various pain states
such as acute pain, persistent and chronic pain, inflammatory pain,
visceral pain, neuropathic pain, nonioceptive pain, and
post-operative pain. NMDA receptor antagonists have also been shown
to attenuate central sensitization and hyperplasia in animals and
humans.
[0352] Neuropathic pain involves an abnormal processing of sensory
input usually occurring after direct injury or damage to nerve
tissue. Neuropathic pain is a collection of disorders characterized
by different etiologies including infection, inflammation, disease
such as diabetes and multiple sclerosis, trauma or compression to
major peripheral nerves, and chemical or irradiation-induced nerve
damage. Neuropathic pain typically persists long after tissue
injury has resolved.
[0353] An essential part of neuropathic pain is a loss (partial or
complete) of afferent sensory function and the paradoxical presence
of certain hyperphenomena in the painful area. The nerve tissue
lesion may be found in the brain, spinal chord, or the peripheral
nervous system. Symptoms vary depending on the condition but are
usually the manifestations hyperalgesia (the lowering of pain
threshold and an increased response to noxious stimuli), allodynia
(the evocation of pain by non-noxious stimuli such as cold, warmth,
or touch), hyperpathia (an explosive pain response that is suddenly
evoked from cutaneous areas with increased sensory detection
threshold when the stimulus intensity exceeds sensory threshold),
paroxysms (a type of evoked pain characterized by shooting,
electric, shock like or stabbing pain that occurs spontaneously, or
following stimulation by an innocuous tactile stimulus or by a
blunt pressure), paraesthesia (abnormal but non-painful sensations,
which can be spontaneous or evoked, often described as pins and
needles), dysesthesia (abnormal unpleasant but not necessarily
painful sensation, which can be spontaneous or provoked by external
stimuli), referred pain and abnormal pain radiation (abnormal
spread of pain), and wind-up like pain and after sensations (the
persistence of pain long after termination of a painful stimulus).
Patients with neuropathic pain typically describe burning,
lancinating, stabbing, cramping, aching and sometimes vice-like
pain. The pain can be paroxysmal or constant. Pathological changes
to the peripheral nerve(s), spinal cord, and brain have been
implicated in the induction and maintenance of chronic pain.
Patients suffering from neuropathic pain typically endure chronic,
debilitating episodes that are refractory to current
pharmacotherapies and profoundly affect their quality of life.
Currently available treatments for neuropathic pain, including
tricyclic antidepressants and gabapentin, typically show limited
efficacy in the majority of patients (Sindrup and Jensen, Pain
1999, 83, 389-400).
[0354] There are several types of neuropathic pain. A
classification that relates to the type of damage or related
pathophysiology causing a painful neuropathy includes neuropathies
associated with mechanical nerve injury such as carpal tunnel
syndrome, vertebral disk herniation, entrapment neuropathies, ulnar
neuropathy, and neurogentic thoracic outlet syndrome; metabolic
disease associated neuropathies such as diabetic polyneuropathy;
neuropathies associated with neurotropic viral disease such as
herpes zoster and human immunodeficiency virus (HIV) disease;
neuropathies associated with neruotoxicity such as chemotherapy of
cancer or tuberculosis, radiation therapy, drug-induced neuropathy,
and alcoholic neuropathy; neuropathies associated with inflammatory
and/or immunolgic mechanisms such as multiple sclerosis,
anti-sulfatide antibody neuropathies, neuropathy associated with
monoclonal gammopathy, Sjogren's disease, lupus, vasculitic
neuropathy, polyclonal inflammatory neuropathies, Guillain-Barre
syndrome, chornic inflammatory demyelinating neuropathy, multifocal
motor neuropathy, paraneoplastic autonomic neuropathy, ganlinoic
acetylcholine receptor antibody autonomic neuropathy, Lambert-Eaton
myasthenic syndrome and myasthenia gravis; neuropathies associated
with nervous system focal ischemia such as thalamic syndrome
(anesthesia dolorosa); neuropathies associated with multiple
neurotransmitter system dysfunction such as complex regional pain
syndrome (CRPS); neuropathies associated with chronic/neuropathic
pain such as osteoarthritis, lower back pain, fibromyalgia, cancer
bone pain, chronic stump pain, phantom limb pain, and
paraneoplastic neuropathies; neuropathies associated with
neuropathic pain including peripheral neuropathies such as
postherpetic neuralgia, toxic neuropathies (e.g., exposure to
chemicals such as exposure to acrylamide, 3-chlorophene,
carbamates, carbon disulfide, ethylene oxide, n-hexane, methyl
n-butylketone, methyl bromide, organophosphates, polychlorinated
biphenyls, pyriminil, trichlorethylene, or dichloroacetylene),
focal traumatic neuropathies, phantom and stump pain,
monoradiculopathy, and trigeminal neuralgia; and central
neuropathies including ischemic cerebrovascular injury (stroke),
multiple sclerosis, spinal cord injury, Parkinson's disease,
amyotrophic lateral sclerosis, syringomyelia, neoplasms,
arachnoiditis, and post-operative pain; mixed neuropathies such as
diabetic neuropathies (including symmetric polyneuropathies such as
sensory or sensorimotor polyneuropathy, selective small-fiber
polyneuropathy, and autonomic neuropathy; focal and multifocal
neuropathies such as cranial neuropathy, limb mononeuropathy, trunk
mononeuro-pathy, mononeuropathy multiplex, and asymmetric lower
limb motor neuropathy) and sympathetically maintained pain. Other
neuropathies include focal neuropathy, glosopharyngeal neuralgia,
ischemic pain, trigeminal neuralgia, atypical facial pain
associated with Fabry's disease, Celiac disease, hereditary sensory
neuropathy, or B.sub.12-deficiency; mono-neuropathies,
polyneuropathis, hereditary peripheral neuropathies such as
Carcot-Marie-Tooth disease, Refsum's disease, Strumpell-Lorrain
disease, and retinitis pigmentosa; acute polyradiculoneuropathy;
and chronic polyradiculoneuropathy. Paraneoplastic neuropathies
include paraneoplastic subacute sensory neuronopathy,
paraneoplastic motor neuron disease, paraneoplastic neuromyotonia,
paraneoplastic demyelinating neuropathies, paraneoplastic
vasculitic neuropathy, and paraneoplastic autonomic
insufficiency.
[0355] The important role of N-methyl-D-aspartate (NMDA) receptors
in the development and maintenance of chronic pain associated with
central and peripheral nerve injury is well documented.
Consequently, NMDA antagonists have been proposed as potential
therapeutics for neuropathic pain. NMDA antagonists of different
classes have shown efficacy in preclinical models as well as in
patients with chronic pain, including neuropathic pain. Several
clinical studies have observed a long-lasting relief in some
neuropathic pain patients treated with NMDA antagonists (Pud et
al., Pain 1998, 75(2-3), 349-54; Eisenberg et al., J Pain 2007,
8(3), 223-9; Rabben et al., J Pharmacol Exp Ther 1999, 289(2),
1060-1066; Correll et al., Pain Med 2004, 5(3), 263-75; and Harbut
et al., US 2005/0148673).
[0356] Other diseases or disorders for which NMDA antagonists and
mGluR.sup.5 antagonists such as acamprosate may be therapeutically
useful include neuroprotection in epilepsy (Chapman et al.,
Neuropharmacol 2000, 39, 1567-1574), cognitive dysfunction (Riedel
et al., Neuropharmacol 2000, 39, 1943-1951), Down's syndrome,
normal cognitive senescence, meningitis, sepsis and septic
encephalophathy, CNS vasculities, leudodystrophies and X-ADL,
childbirth and surgical anesthesia, spinal cord injury,
hypoglycemia, encephalopathy, tumors and malignancies, cerebellar
degenerations, ataxias, bowel syndromes, metabolic bone disease and
osteoporosis, obesity, diabetes and pre-diabetic syndromes (Storto
et al., Molecular Pharmacology 2006, 69(4), 1234-1241), and
gastroesophageal reflux disease (Jensen et al., Eur J Pharmacology
2005, 519, 154-157).
Administration
[0357] Prodrugs of Formula (I), pharmaceutically acceptable salts
of any of the foregoing, and/or pharmaceutical compositions thereof
may be administered orally. Prodrugs of Formula (I) and/or
pharmaceutical compositions thereof may also be administered by any
other convenient route, for example, by infusion or bolus
injection, by absorption through epithelial or mucocutaneous
linings (e.g., oral mucosa, rectal, and intestinal mucosa, etc.).
Administration may be systemic or local. Various delivery systems
are known, (e.g., encapsulation in liposomes, microparticles,
microcapsules, capsules, etc.) that may be used to administer a
compound and/or pharmaceutical composition. Prodrugs of Formula (I)
a pharmaceutically acceptable salt of any of the foregoing, or a
pharmaceutical composition thereof may be administered by any
appropriate route. Examples of suitable routes of administration
include, but are not limited to, intradermal, intramuscular,
intraperitoneal, intravenous, subcutaneous, intranasal, epidural,
oral, sublingual, intracerebral, intravaginal, transdermal, rectal,
inhalation, or topical.
[0358] In certain embodiments, it may be desirable to introduce
prodrugs of Formula (I) and/or pharmaceutical compositions thereof
into the central nervous system, which may be by any suitable
route, including intraventricular, intrathecal, and epidural
injection. Intraventricular injection may be facilitated using an
intraventricular catheter attached to a reservoir such as an Ommaya
reservoir.
[0359] The amount of a prodrug of Formula (I) that will be
effective in the treatment of a disease in a patient will depend,
in part, on the nature of the condition and can be determined by
standard clinical techniques known in the art. In addition, in
vitro or in vivo assays may be employed to help identify optimal
dosage ranges. A therapeutically effective amount of prodrug of
Formula (I) to be administered may also depend on, among other
factors, the subject being treated, the weight of the subject, the
severity of the disease, the manner of administration, and the
judgment of the prescribing physician.
[0360] For systemic administration, a therapeutically effective
dose may be estimated initially from in vitro assays. For example,
a dose may be formulated in animal models to achieve a beneficial
circulating composition concentration range. Initial doses may also
be estimated from in vivo data, e.g., animal models, using
techniques that are known in the art. Such information may be used
to more accurately determine useful doses in humans. One having
ordinary skill in the art may optimize administration to humans
based on animal data.
[0361] A dose may be administered in a single dosage form or in
multiple dosage forms. When multiple dosage forms are used the
amount of compound contained within each dosage form may be the
same or different. The amount of a compound of Formula (I)
contained in a dose may depend on the route of administration and
whether the disease in a patient is effectively treated by acute,
chronic, or a combination of acute and chronic administration.
[0362] In certain embodiments an administered dose is less than a
toxic dose. Toxicity of the compositions described herein may be
determined by standard pharmaceutical procedures in cell cultures
or experimental animals, e.g., by determining the LD.sub.50 (the
dose lethal to 50% of the population) or the LD.sub.100 (the dose
lethal to 100% of the population). The dose ratio between toxic and
therapeutic effect is the therapeutic index. In certain
embodiments, an acamprosate prodrug may exhibit a high therapeutic
index. The data obtained from these cell culture assays and animal
studies may be used in formulating a dosage range that is not toxic
for use in humans. A dose of an acamprosate prodrug provided by the
present disclosure may be within a range of circulating
concentrations in for example the blood, plasma, or central nervous
system, that include the effective dose and that exhibits little or
no toxicity. A dose may vary within this range depending upon the
dosage form employed and the route of administration utilized. In
certain embodiments, an escalating dose may be administered.
Combination Therapy
[0363] In certain embodiments, prodrugs of Formula (I) or
pharmaceutically acceptable salts of any of the foregoing can be
used in combination therapy with at least one other therapeutic
agent. Prodrugs of Formula (I) and the at least one other
therapeutic agent(s) may act additively or, in certain embodiments,
synergistically. In certain embodiments, prodrugs of Formula (I) be
administered concurrently with the administration of another
therapeutic agent. In certain embodiments, prodrugs of Formula (I)
or pharmaceutically acceptable salts of any of the foregoing may be
administered prior or subsequent to administration of another
therapeutic agent. The at least one other therapeutic agent may be
effective for treating the same or different disease or
disorder.
[0364] When used to treat a disease or disorder a therapeutically
effective amount of one or more compounds of Formula (I) may be
administered singly, or in combination with other agents including
pharmaceutically acceptable vehicles and/or pharmaceutically active
agents for treating a disease or disorder, which may be the same or
different disease or disorder as the disease or disorder being
treated by the one or more compounds of Formula (I). A
therapeutically effective amount of one or more compounds of
Formula (I) may be delivered together with a compound disclosed
herein or combination with another pharmaceutically active
agent.
[0365] Methods of the present disclosure include administration of
one or more compounds of Formula (I), or pharmaceutical
compositions thereof and another therapeutic agent provided the
other therapeutic agent does not inhibit the therapeutic efficacy
of the one or more compounds of Formula (I) and/or does not produce
adverse combination effects.
[0366] In certain embodiments, compositions provided by the present
disclosure may be administered concurrently with the administration
of another therapeutic agent, which can be part of the same
pharmaceutical composition as, or in a different composition than
that containing the compound provided by the present disclosure. In
certain embodiments, a compound of Formula (I) may be administered
prior or subsequent to administration of another therapeutic agent.
In certain embodiments of combination therapy, the combination
therapy comprises alternating between administering a composition
of Formula (I) and a composition comprising another therapeutic
agent, e.g., to minimize adverse side effects associated with a
particular drug. When a compound of Formula (I) is administered
concurrently with another therapeutic agent that may produce
adverse side effects including, but not limited to, toxicity, the
other therapeutic agent may be administered at a dose that falls
below the threshold at which the adverse side effect is
elicited.
[0367] In certain embodiments, a pharmaceutical composition may
further comprise substances to enhance, modulate and/or control
release, bioavailability, therapeutic efficacy, therapeutic
potency, stability, and the like. For example, to enhance
therapeutic efficacy a compound of Formula (I) may be
co-administered with one or more active agents to increase the
absorption or diffusion of the compound from the gastrointestinal
tract or to inhibit degradation of the drug in the systemic
circulation. In certain embodiments, a compound of Formula (I) may
be co-administered with active agents having a pharmacological
effect that enhance the therapeutic efficacy of the drug.
[0368] In certain embodiments, compounds of Formula (I) or
pharmaceutical compositions thereof include, or may be administered
to a patient together with, another compound for treating a
neurodegenerative disorder, a psychotic disorder, a mood disorder,
an anxiety disorder, a somatoform disorder, movement disorder, a
substance abuse disorder, binge eating disorder, a cortical
spreading depression related disorder, tinnitus, a sleeping
disorder, multiple sclerosis, or pain.
[0369] In certain embodiments, acamprosate prodrugs provided by the
present disclosure and pharmaceutical compositions thereof may be
administered to a patient for treating a neurodegenerative disorder
in combination with a therapy or another therapeutic agent known or
believed to be effective in treating a neurodegenerative disorder.
In certain embodiments, a neurodegenerative disorder is chosen from
Alzheimer's disease, Parkinson's disease, Huntington's disease, and
amyotrophic lateral sclerosis.
[0370] Therapeutic agents useful for treating Parkinson's disease
include dopamine precursors such levodopa, dopamine agonists such
as bromocriptine, pergolide, pramipexole, and ropinirole, MAO-B
inhibitors such as selegiline, anticholinergic drugs such as
benztropine, trihexyphenidyl, tricyclic antidepressants such as
amitriptyline, amoxapine, clomipramine, desipramine, doxepin,
imipramine, maprotiline, nortriptyline, protriptyline, amantadine,
and trimipramine, some antihistamines such as diphenhydramine;
antiviral drugs such as amantadine; and .beta.-blockers such as
propranolol.
[0371] Useful drugs for treating Alzheimer's disease include
rosiglitazone, roloxifene, vitamin E, donepezil, tacrine,
rivastigmine, galantamine, and memantine.
[0372] Useful drugs for treating symptoms of Huntington's disease
include antipsychotics such as haloperidol, chlorpromazine and
olanzapine to control hallucinations, delusions and violent
outbursts; antidepressants such as fluoxetine, sertraline, and
nortryiptyline to control deptression and obsessive-compulsive
behavior; tranquilizers such as benzodiazepines, paroxetine,
venflaxin and beta-blockers to control anxiety and chorea; mood
stabilizers such as liethium, valproate, and carbamzepine to
control mania and bipolar disorder; and botulinum toxin to control
dystonia and jaw clenching. Useful drugs for treating symptoms of
Huntington's disease further include selective serotonin reuptake
inhibitors (SSRI) such as fluoxetine, paroxetine, sertraline,
escitalopram, citalopram, fluvosamine; norepinephrine and serotonin
reuptake inhibitors (NSRI) such as venlafaxine and duloxetine,
benzodiazepines such as clonazepam, alprazolam, diazepam, and
lorazepam, tricyclic antidepressants such as as amitriptyline,
nortriptyline, and imipramine; and atypical antidepressants such as
busipirone, bupriopion, and mirtazepine for treating the symptoms
of anxiety and depression; atomoxetine, dextroamphetamine, and
modafinil for treating apathy symptoms; amantadine, memantine, and
tetrabenazine for treating chorea symptoms; citalopram,
atomoxetine, memantine, rivastigmine, and donepezil for treating
cognitive symptoms; lorazepam and trazedone for treating insomnia;
valproate, carbamazepine and lamotrigine for treating symptoms of
irritability; SSRI antidepressants such as fluoxetine, paroxetine,
sertaline, and fluvoxamine, NSRI antidpressants such as
venlafaxine, and others such as mirtazepine, clomipramine,
lomotrigine, gabapentin, valproate, carbamazepine, olanzapine,
rispiridone, and quetiapine for treating symptoms of
obsessive-compulsive disorder; haloperidol, quetiapine, clozapine,
risperidone, olanzapine, ziprasidone, and aripiprazole for treating
psychosis; and pramipexole, levodopa and amantadine for treating
rigidity.
[0373] Useful drugs for treating ALS include riluzole. Other drugs
of potential use in treating ALS include memantine, tamoxifen,
thalidomide, cefiriaxone, sodium phenyl butyrate, celecoxib,
glatiramer acetate, busipirone, creatine, minocycline, coenzyme
Q10, oxandrolone, IGF-1, topiramate, xaliproden, and indinavir.
Drugs such as baclofen and diazepam can be useful in treating
spasticity associated with ALS.
[0374] In certain embodiments, acamprosate prodrugs provided by the
present disclosure and pharmaceutical compositions thereof may be
administered to a patient for treating a psychotic disorder in
combination with a therapy or another therapeutic agent known or
believed to be effective in treating a psychotic disorder. In
certain embodiments a psychotic disorder is schizophrenia.
[0375] Examples of antipsychotic agents useful in treating positive
symptoms of schizophrenia include, but are not limited to,
acetophenazine, alseroxylon, amitriptyline, aripiprazole,
astemizole, benzquinamide, carphenazine, chlormezanone,
chlorpromazine, chlorprothixene, clozapine, desipramine,
droperidol, aloperidol, fluphenazine, flupenthixol, glycine,
oxapine, mesoridazine, molindone, olanzapine, ondansetron,
perphenazine, pimozide, prochlorperazine, procyclidine, promazine,
propiomazine, quetiapine, remoxipride, reserpine, risperidone,
sertindole, sulpiride, terfenadine, thiethylperzaine, thioridazine,
thiothixene, trifluoperazine, triflupromazine, trimeprazine, and
ziprasidone. Examples of typical antipsychotic agents useful for
treating positive symptoms of schizophrenia include acetophenazine,
chlorpromazine, chlorprothixene, droperidol, fluphenazine,
haloperidol, loxapine, mesoridazine, methotrimeprazine, molindone,
perphenazine, pimozide, raclopride, remoxipride, thioridazine,
thiothixene, and trifluoperazine. Examples of atypical
antipsychotic agents useful for treating positive symptoms of
schizophrenia include aripiprazole, clozapine, olanzapine,
quetiapine, risperidone, sertindole, and ziprasidone.
[0376] Other antipsychotic agents useful for treating positive
symptoms of schizophrenia include amisulpride, balaperidone,
blonanserin, butaperazine, carphenazine, eplavanserin, iloperidone,
lamictal, onsanetant, paliperidone, perospirone, piperacetazine,
raclopride, remoxipride, sarizotan, sonepiprazole, sulpiride,
ziprasidone, and zotepine; serotonin and dopamine (5HT/D2) agonists
such as asenapine and bifeprunox; neurokinin 3 antagonists such as
talnetant and osanetant; AMPAkines such as CX-516, galantamine,
memantine, modafinil, ocaperidone, and tolcapone; and .alpha.-amino
acids such as D-serine, D-alanine, D-cycloserine, and
N-methylglycine. Thus, antipsychotic agents include typical
antipsychotic agents, atypical antipsychotic agents, and other
compounds useful for treating schizophrenia in a patient, and
particularly useful for treating the positive symptoms of
schizophrenia.
[0377] Examples of agents useful for treating cognitive and/or
negative symptoms of schizophrenia include aripiprazole, clozapine,
olanzapine, quetiapine, risperidone, sertindole, ziprasidone,
asenapine, bifeprunox, iloperidone, lamictal, galantamine,
memantine, modafininil, acaperidone, NK3 antagonists such as
talnetant and osanetant, AMPAkines, tolcapone, amisulpride,
mirtazapine, lamotrigine, idazoxan, neboglamine, sabcomeline,
ispronicline, sarcosine, preclamol, L-camosine, nicotine,
raloxifene, pramipexol, escitalopram, estradiol, riluzole,
creatine, entacapone, L-threonine, atomoxetine, divalproex sodium,
pimozide, provastatin, duloxetine; and NMDA receptor modulators
such as glycine, D-serine, and D-cycloserine.
[0378] In certain embodiments, pharmaceutical compositions provided
by the present disclosure may be co-administered with another drug
useful for treating a symptom of schizophrenia or a disease,
disorder, or condition associated with schizophrenia and that is
not an antipsychotic agent. For example, acamprosate prodrugs may
be co-administered with an antidepressant, such as, but not limited
to alprazolam, amitriptyline, amoxapine, bupropion, citalopram,
clomipramine, desipramine, eoxepin, escitapopram, fluoxetine,
fluvoxamine, imipramine, maprotiline, methylphenidate, mirtazapine,
nefazodone, nortriptyline, paroxetine, phenelzine, protriptyline,
sertraline, tranylcypromine, trazodone, trimipramine, venlafaxine,
and combinations of any of the foregoing.
[0379] For example, in certain embodiments, an acamprosate prodrug
provided by the present disclosure, or pharmaceutical compositions
thereof may be administered to a patient for the treatment of
schizophrenia in conjunction with a social therapy for treating
schizophrenia such as rehabilitation, community support activities,
cognitive behavioral therapy, training in illness management
skills, participation in self-help groups, and/or psychotherapy.
Examples of psychotherapies useful for treating schizophrenia
include Alderian therapy, behavior therapy, existential therapy,
Gestalt therapy, person-centered therapy, psychoanalytic therapy,
rational-emotive and cognitive-behavioral therapy, reality therapy,
and transactional analysis.
[0380] Other examples of drugs useful for treating psychotic
disorders include aripiprazole, loxapine, mesoridazine, quetiapine,
reserpine, thioridazine, trifluoperazine, and ziprasidone,
chlorpromazine, clozapine, fluphenazine, haloperidol, olanzapine,
perphenazine, prochlorperazine, risperidone, and thiothixene.
[0381] In certain embodiments, acamprosate prodrugs provided by the
present disclosure and pharmaceutical compositions thereof may be
administered to a patient for treating a mood disorder in
combination with a therapy or another therapeutic agent known or
believed to be effective in treating a mood disorder. In certain
embodiments, a mood disorder is chosen from a bipolar disorder and
a depressive disorder.
[0382] Examples of drugs useful for treating bipolar disorder
include aripirprazole, verapamil, carbamazepine, clonidine,
clonazepam, lamotrigine, olanzapine, quetiapine, fluoxetine, and
ziprasidone.
[0383] In certain embodiments, acamprosate prodrugs provided by the
present disclosure and pharmaceutical compositions thereof may be
administered to a patient for treating depression in combination
with a therapy or another therapeutic agent known or believed to be
effective in treating depression.
[0384] Examples of drugs useful for treating depression include
tricyclics such as amitriptyline, amoxapine, clomipramine,
desipramine, doxepin, imipramine, maprotiline, nortryptyline,
protryptyline, and trimipramine; tetracyclics such as maprotiline
and mirtazapine; selective serotonin reuptake inhibitors (SSRI)
such as citalopram, escitalopram, fluoxetine, fluvoxamine,
paroxetine, and sertraline; serotonin and norepinephrine reuptake
inhibitors (SNRI) such as venlafaxine and duloxetine; monoamine
oxidase inhibitors such as isocarboxazid, phenelzine, selegiline,
and tranylcypromine; psychostimulants such as dextroamphetamine and
metylphenidate; and other drugs such as bupropion, mirtazapine,
nefazodone, trazodone, lithium, and venlafaxine.
[0385] In certain embodiments, acamprosate prodrugs provided by the
present disclosure and pharmaceutical compositions thereof may be
administered to a patient for treating an anxiety disorder in
combination with a therapy or another therapeutic agent known or
believed to be effective in treating an anxiety disorder.
[0386] Examples of drugs for useful treating anxiety disorders
include alprazolam, atenolol, busipirone, chlordiazepoxide,
clonidine, clorazepate, diazepam, doxepin, escitalopram, halazepam,
hydroxyzine, lorazepam, nadolol, oxazepam, paroxetine,
prochlorperazine, trifluoperazine, venlafaxine, amitriptyline,
sertraline, citalopram, clomipramine, fluoxetine, fluvoxamine, and
paroxetine.
[0387] In certain embodiments, acamprosate prodrugs provided by the
present disclosure and pharmaceutical compositions thereof may be
administered to a patient for treating a somatoform disorder in
combination with a therapy or another therapeutic agent known or
believed to be effective in treating a somatoform disorder.
[0388] Examples of drugs useful for treating somatoform disorders
include tricyclic antidepressants such as amitriptyline, and
serotonin reuptake inhibitors.
[0389] In certain embodiments, acamprosate prodrugs provided by the
present disclosure and pharmaceutical compositions thereof may be
administered to a patient for treating a movement disorder in
combination with a therapy or another therapeutic agent known or
believed to be effective in treating a movement disorder. In
certain embodiments, a movement disorder is selected from tardive
dyskinesia and spasticity.
[0390] Examples of drugs useful for treating movement disorders
include levodopa, mild sedatives such as benzodiazepines including
alprazolam, chlordiazepoxide, clonazepam, clorazepate, diazepam,
lorazepam, and oxazepam; muscle relaxants such as baclofen,
anticholinergic drugs such as trihexyphenidyl and diphenhydramine;
antipsychotics such as chlorpromazine, fluphenazine, haloperidol,
loxapine, mesoridazine, molindone, perphenazine, pimozide,
thioridazine, thiothixene, trifluoperazine, aripiprazole,
clozapine, olanzapine, quetiapine, risperidone, and ziprasidone;
and antidepressants such as amitriptyline.
[0391] Examples of drugs useful for treating tardive dyskinesia
include vitamin E, dizocilpine, memantine, clzapine, lorazepam,
diazepam, clonazepam, glycine, D-cycloserine valproic acid,
amantadine, ifenprodil, and tetrabenazine.
[0392] Examples of drugs useful for treating spasticity include
baclofen, R-baclofen, diazepam, tizanidine, clonidine, dantrolene,
4-aminopyridine, cyclobenzaprine, ketazolam, tiagabine, and
botulinum A toxin. Compounds having activity as .alpha.2.delta.
subunit calcium channel modulators such as gabapentin and
pregabalin are believed to be useful as antispasticity agents.
[0393] In certain embodiments, acamprosate prodrugs provided by the
present disclosure and pharmaceutical compositions thereof may be
administered to a patient for treating a substance abuse disorder
in combination with a therapy or another therapeutic agent known or
believed to be effective in treating a substance abuse disorder. In
certain embodiments, a substance abuse disorder is chosen from an
alcohol abuse disorder, a narcotic abuse disorder, and a nicotine
abuse disorder.
[0394] Examples of drugs useful for treating alcohol dependency or
alcohol abuse disorders include disulfiram, naltrexone,
acamprosate, ondansetron, atenolol, chlordiazepoxide, clonidine,
clorazepate, diazepam, oxazepam, methadone, topiramate,
1-alpha-acetylmethadol, buprenorphine, bupropion, and baclofen.
[0395] Examples of drugs useful for treating opioid abuse disorders
include buprenorphine, naloxone, tramadol, methadone, and
naltrexone.
[0396] Examples of drugs useful for treating cocaine abuse
disorders include disulfiram, modafinil, propranolol, baclofen,
vigabatrin, and topiramate.
[0397] Examples of drugs useful for treating nicotine abuse
disorders include bupropion, clonidine, rimonabant, verenicline,
and nicotine.
[0398] In certain embodiments, acamprosate prodrugs provided by the
present disclosure and pharmaceutical compositions thereof may be
administered to a patient for treating a cortical spreading
depression related disorder in combination with a therapy or
another therapeutic agent known or believed to be effective in
treating a cortical spreading depression related disorder. In
certain embodiments, a cortical spreading depression related
disorder is selected from migraine, cerebral injury, epilepsy, and
cardiovascular disease.
[0399] Drugs useful for treating migraine can prevent a migraine
from occurring, abort a migraine that is beginning, or relieve pain
during the migraine episode.
[0400] Prophylactic migraine treatments reduce the frequency of
migraines and include non-steroidal anti-inflammatory agents
(NSAIDs), adrenergic beta-blockers, calcium channel blockers,
tricyclic antidepressants, selective serotonin reuptake inhibitors,
anticonvulsants, NMDA receptor antagonists, angiotensin converting
enzyme (ACE) inhibitors, angiotensin-receptor blockers (ARBs),
leukotriene-antagonists, dopamine agonists, selective 5HT-1D
agonists, selective 5HT-1F agonists, AMPA/KA antagonists, CGRP
(calcitonin gene related peptide) antagonists, NOS (nitric oxide
synthase) inhibitors, blockers of spreading cortical depression,
and other therapy. Examples of NSAIDs useful for preventing
migraine include aspirin, ibuprofen, fenoprofen, flurbiprofen,
ketoprofen, mefenamic acid, and naproxen. Examples of adrenergic
beta-blockers useful for preventing migraine include acebutolol,
atenolol, imilol, metoprolol, nadolol, pindolol, propranolol, and
timolol. Examples of calcium channel blockers useful for preventing
migraine include amlodipine, diltiazem, dotarizine, felodipine,
flunarizine, nicardipine, nifedipine, nimodipine, nisoldipine, and
verapamil. Examples of tricyclic antidepressants useful for
preventing migraine include amitriptyline, desipramine, doxepin,
imipramine, nortriptyline, and protriptyline. Examples of selective
serotonin reuptake inhibitors (SSRIs) useful for preventing
migraine include fluoxetine, methysergide, nefazodone, paroxetine,
sertraline, and venlafaxine. Examples of other antidepressants
useful for preventing migraine include bupropion, nefazodone,
norepinephrine, and trazodone.
[0401] Examples of anticonvulsants (antiepileptics) useful for
preventing migraine include divalproex sodium, felbamate,
gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine,
topiramate, valproate, and zonisamide. Examples of NMDA receptor
antagonists useful for preventing migraine include
dextromethorphan, magnesium, and ketamine. Examples of angiotensin
converting enzyme (ACE) inhibitors useful for preventing migraine
include lisinopril. Examples of angiotensin-receptor blockers
(ARBs) useful for preventing migraine include candesartan. Examples
of leukotriene-antagonists useful for preventing migraine include
zileuton, zafirlukast, montelukast, and pranlukast. Examples of
dopamine agonists useful for preventing migraine include
.alpha.-dihydroergocryptine. Examples of other therapy useful for
preventing migraine include botulinum toxin, magnesium, hormone
therapies, riboflavin, methylergonovine, cyproheptadine, and
phenelzine, and complementary therapies such as
counseling/psychotherapy, relaxation training, progressive muscle
relaxation, guided imagery, diaphragmatic breathing, biofeedback,
acupuncture, and physical and massage therapy.
[0402] Acute migraine treatments intended to eliminate or reduce
the severity of the headache and any associated symptoms after a
migraine has begun include serotonin receptor agonists, such as
triptans (5-hydroxytryptophan (5-HT) agonists) including
almotriptan, eletriptan, frovatriptan, naratriptan, rizatriptan,
sumatriptan, imotriptan, and zolmitriptan; ergotamine-based
compounds such as dihydroergotamine and ergotamine; antiemetics
such as metoclopramide and prochlorperazine; and compounds that
provide analgesic effects.
[0403] Other examples of drugs used to treat migraine once started
include, acetaminophen-aspirin, caffeine, cyproheptadine,
methysergide, valproic acid, NSAIDs such as diclofenac,
flurbiprofen, ketaprofen, ketorolac, ibuprofen, indomethacin,
meclofenamate, and naproxen sodium, opioids such as codeine,
meperidine, and oxycodone, and glucocorticoids including
dexamethasone, prednisone and methylprednisolone.
[0404] GABA analog prodrugs provided by the present disclosure may
also be administered in conjunction with drugs that are useful for
treating symptoms associated with migraine such as nausea and
vomiting, and depression. Examples of useful therapeutic agents for
treating or preventing vomiting include, but are not limited to,
5-HT.sub.3 receptor antagonists such as ondansetron, dolasetron,
granisetron, and tropisetron; dopamine receptor antagonists such as
prochlorperazine, thiethylperazine, chlorpromazine, metoclopramide,
and domperidone; glucocorticoids such as dexamethasone; and
benzodiazepines such as lorazepam and alprazolam. Examples of
useful therapeutic agents for treating or preventing depression
include, but are not limited to, tricyclic antidepressants such as
amitryptyline, amoxapine, bupropion, clomipramine, desipramine,
doxepin, imipramine, maprotiline, nefazadone, nortriptyline,
protriptyline, trazodone, trimipramine, and venlafaxine; selective
serotonin reuptake inhibitors such as fluoxetine, fluvoxamine,
paroxetine, and setraline; monoamine oxidase inhibitors such as
isocarboxazid, pargyline, phenizine, and tranylcypromine; and
psychostimulants such as dextroamphetamine and methylphenidate.
[0405] Useful drugs for treating cerebral trauma include
corticosteroids such as betainethasone, budesonide, cortisone,
dexamethasone, hydrocortisone, methylprednisolone, predisolone,
prednisone, and triamcinolone, and antithrombotics such as
ticlopidine.
[0406] Useful drugs for treating epilepsy include acetazolamide,
carbamazepine, gabapentin, mephobarbital, felbamate, fosphenytoin,
phenytoin, pregabalin, and valproic acid.
[0407] In certain embodiments, acamprosate prodrugs provided by the
present disclosure and pharmaceutical compositions thereof may be
administered to a patient for treating tinnitus in combination with
a therapy or another therapeutic agent known or believed to be
effective in treating tinnitus.
[0408] A second therapeutic agent for treating or preventing
tinnitus can have one or more of analgesic, anesthetic, sodium
channel blocker, antiedemic, analgesic, and antipyretic properties.
Analgesics include, for example, steroidal anti-inflammatory
agents, non-steroidal anti-inflammatory agents, selective COX-2
inhibitors, and narcotics. Examples of analgesics include, for
example, acetaminophen, amitriptyline, aspirin, buprenorphine,
celecoxib, clonidine, codeine, diclofenac, diflunisal, etodolac,
fenoprofen, fentanyl, flurbiprofen, hydromorphone, hydroxyzine,
ibuprofen, imipramine, indomethacin, ketoprofen, ketorolac,
levorphanol, meperidine, methadone, morphine, naproxen, oxycodone,
piroxicam, propoxyphene, refecoxib, sulindac, tolmetin, tramadol,
valdecoxib, and combinations of any of the foregoing.
[0409] In certain embodiments, a compound of the present disclosure
or pharmaceutical composition thereof can be administered with a
N-methyl-D-aspartate (NMDA) receptor antagonist that binds to the
NMDA receptor at the competitive NMDA antagonist binding site, the
non-competitive NMDA antagonist binding site within the ion
channel, or to the glycine site. Examples of NMDA receptor
antagonists include amantadine, D-2-amino-5-phosphonopentanoic acid
(D-AP5), 3-((.+-.)2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid
(CCP), conantokins, 7-chlorokynurenate (7-CK), dextromethorphan,
ifenprodil, ketamine, memantine, dizocilpine, gacyclidine,
licostinel, phencyclidine, riluzole, traxoprodil, and combinations
of any of the foregoing (Sands, U.S. Pat. No. 5,716,961 and Guitton
et al., US 2006/0063802). Other drugs that may be useful in
treating tinnitus include baclofen, caroverine, piribedil,
nimodipine, clonazepam, and trimetazidine.
[0410] An acamprosate prodrug of Formula (I) or pharmaceutical
composition thereof can also be used in conjunction with
non-pharmacological tinnitus therapies such as, for example,
avoidance of ototoxic medications, reduced consumption of alcohol,
caffeine and nicotine, reduced stress, the use of background noises
or maskers, behavioral therapies such as hypnosis, cognitive
therapy, biofeedback, tinnitus retraining therapy.
[0411] In certain embodiments, acamprosate prodrugs provided by the
present disclosure and pharmaceutical compositions thereof may be
administered to a patient for treating a sleeping disorder in
combination with a therapy or another therapeutic agent known or
believed to be effective in treating a sleeping disorder.
[0412] Examples of drugs useful for treating sleep apnea include
mirtiazapine and modafinil.
[0413] In certain embodiments, acamprosate prodrugs provided by the
present disclosure and pharmaceutical compositions thereof may be
administered to a patient for treating multiple sclerosis in
combination with a therapy or another therapeutic agent known or
believed to be effective in treating multiple sclerosis.
[0414] Examples of drugs useful for treating MS include
corticosteroids such as methylprednisolone; IFN-.beta. such as
IFN-.beta.1a and IFN-.beta.1b; glatiramer acetate; monoclonal
antibodies that bind to the very late antigen-4 (VLA-4) integrin
such as natalizumab; immunomodulatory agents such as FTY 720
sphinogosie-1 phosphate modulator and COX-2 inhibitors such as
BW755c, piroxicam, and phenidone; and neuroprotective treatments
including inhibitors of glutamate excitotoxicity and iNOS,
free-readical scaventers, and cationic channel blockers; memantine;
AMPA antagonists such as topiramate; and glycine-site NMDA
antagonists.
[0415] In certain embodiments, acamprosate prodrugs provided by the
present disclosure and pharmaceutical compositions thereof may be
administered to a patient for treating pain in combination with a
therapy or another therapeutic agent known or believed to be
effective in treating pain. In certain embodiments, the pain is
neuropathic pain.
[0416] Examples of drugs useful for treating pain include opioid
analgesics such as morphine, codeine, fentanyl, meperidine,
methadone, propoxyphene, levorphanol, hydromorphone, oxycodone,
oxymorphone, and pentazocine; nonopioid analgesics such as aspirin,
ibuprofen, ketoprofen, naproxen, and acetaminophen; nonsteroidal
anti-inflammatory drugs such as aspirin, choline magnesium
trisalicylate, diflunisal, salsalate, celecoxib, rofecoxib,
valdecoxib, diclofenac, etodolac, fenoprofen, flubiprofen,
ibuprofen, indomethacin, ketoprofen, ketorolac, meclofanamate,
mefenamic acid, meloxicam, nabumetone, naproxen, oxaprozin,
piroxicam, sulindac, and tometin; and other drugs such as
amitriptyline, desipramine, gabapentin, carbamazepine, phenytoin,
clonazepam, divalproex, lamotrigine, topiramate, oxcarbazepine,
divalproex, butorphanol, tramadol, valdecoxib, vicoprofen,
pentazocine, propoxyhene, fenoprofen, piroxicam, indometnacin,
hydroxyzine, buprenorphine, benzocaine, clonidine, flurbiprofen,
and meperidine.
[0417] The weight ratio of compounds of Formula (I) to a second
therapeutic agent may be varied and may depend upon the effective
dose of each agent. A therapeutically effective dose of each
compound will be used. Thus, for example, when a compound of
Formula (I) is combined with another therapeutic agent, the weight
ratio of the compound provided by the present disclosure to the
second therapeutic agent can be from about 1000:1 to about 1:1000,
and in certain embodiments, from about 200:1 to about 1:200.
[0418] Combinations of compounds of Formula (I) and a second
therapeutic agent may also be within the aforementioned range, but
in each case, an effective dose of each active compound can be
used. In such combinations a compound of Formula (I) and second
therapeutic agent may be administered separately or in conjunction.
In addition, administration of one agent may be prior to,
concurrent with, or subsequent to the administration of another
therapeutic agent(s). Accordingly, compounds of Formula (I) may be
used alone or in combination with other therapeutic agents that are
known to be beneficial in treating the same disease being treated
with the compound of Formula (I) or other therapeutic agents that
affect receptors or enzymes that either increase the efficacy,
safety, convenience, or reduce unwanted side effects or toxicity of
the compound of Formula (I). Compounds of Formula (I) and the other
therapeutic agent may be co-administered, either in concomitant
therapy or in a fixed combination. The additional therapeutic agent
may be administered by the same or different route than the route
used to administer a compound of Formula (I) or pharmaceutical
composition of any of the foregoing.
EXAMPLES
[0419] The following examples describe in detail synthesis of
compounds of Formula (I)-(II), properties of compounds of Formula
(I)-(II), and uses of compounds of Formula (I)-(II). It will be
apparent to those skilled in the art that many modifications, both
to materials and methods, may be practiced without departing from
the scope of the disclosure.
Description 1
General Experimental Protocols
[0420] All reagents and solvents were purchased from commercial
suppliers and used without further purification or
manipulation.
[0421] Proton NMR spectra (400 MHz) were recorded on a Varian AS
400 NMR spectrometer equipped with an autosampler and data
processing computation. CDCl.sub.3 (99.8% D), DMSO-d.sup.6 (99.9%
D), or MeOH-d.sup.4 (99.8+% D) were used as solvents unless
otherwise noted. The CHCl.sub.3, DMSO-d.sup.5, or MeOH-d.sup.3
solvent signals were used for calibration of the individual
spectra. Determination of enantiomeric excess (e.e.) of
intermediates was accomplished by 1H NMR-spectroscopy in the
presence of the diamagnetic enantiomerically pure chiral co-solvent
(R)-(-)-2,2,2-trifluoro-1-(9-anthryl)ethanol (Pirkle-alcohol) and
in comparison NMR-spectra of the corresponding racemic samples
under similar conditions (Parker, Chem. Rev., 1991, 91, 1441-1457).
Analytical thin layer chromatography (TLC) was performed using
Whatman, Schleicher & Schuell TLC. MK6F silica gel plates
(2.5.times.7.5 cm, 250 .mu.m layer thickness). Dyeing or staining
reagents for TLC detection and visualization were prepared
according methods known in the art. Ozonolysis reactions were
performed using a Welsbach Standard T-series ozone generator.
Analytical LC/MS was performed on a Waters 2790 separation module
equipped with a Waters Micromass QZ mass spectrometer, a Waters 996
photodiode detector, and a Merck Chromolith UM2072-027 or
Phenomenex Luna C-18 analytical column. Mass-guided preparative
HPLC purification of final compounds was performed on an instrument
equipped with a Waters 600 controller, ZMD Micromass spectrometer,
a Waters 2996 photodiode array detector, and a Waters 2700 Sample
Manager. Acetonitrile/water gradients containing 0.05% formic acid
were used as eluent in both analytical and preparative HPLC
experiments. Compound isolation from aqueous solvent mixtures,
e.g., acetonitrile/water/0.05% formic acid, was accomplished by
primary lyophilization (freeze drying) of the frozen solutions
under reduced pressure at room temperature using manifold freeze
dryers such as Heto Drywinner DW 6-85-1, Heto FD4, or VIRTIS
Freezemobile 25 ES equipped with a high vacuum pump. Optionally,
and if the isolated compound had ionizable functional groups such
as an amino group or a carboxylic acid, the lyophilization process
was conducted in the presence of a slight excess of one molar (1.0
M) hydrochloric acid to yield the purified compounds as the
corresponding hydrochloride salt (HCl-salt) or the corresponding
protonated free carboxylic acid.
[0422] Chemical names were generated with Chemistry 4-D Draw Pro
Version 7.01c (Draw Chemical Structures Intelligently.COPYRGT.
1993-2002) from ChemInnovation Software, Inc., San Diego, USA).
Example 1
Synthesis of N-[3-(Chlorosulfonyl)propyl]acetamide (1)
Step A: Tetramethylammonium N-acetylhomotaurate (1a)
[0423] Tetramethylammonium N-acetylhomotaurate (1a) was synthesized
adapting procedures disclosed in Durlach, U.S. Pat. No. 4,355,043,
DE 3019350, and U.S. Pat. No. 4,199,601. A 250 mL round bottomed
flask equipped with a magnetic stir bar was charged with
3-amino-1-propanesulfonic acid (5.0 g, 36.0 mmol) and 20 mL of
water. To the stirred solution, 13.0 g (36.0 mmol) of
tetramethylammonium hydroxide (25 w-% in water) was added. The
solution was stirred at room temperature for 1 hour and acetic
anhydride 4.1 mL (4.39 g, 43.0 mmol) was added. The mixture was
stirred overnight at ca. 40.degree. C. (oil bath) to ensure
complete conversion. The resulting solution was extracted twice
with 30 mL of diethyl ether or tert-butyl methyl ether (MTBE), and
residual methanol in the aqueous phase was removed under reduced
pressure using a rotary evaporator. The extract was isolated from
the residual water in the solution by lyophilization to yield 9.1 g
(quant.) of the title compound (1a) as a colorless powder that was
used without further purification after additional thorough drying
under high vacuum. .sup.1H NMR (400 MHz, D.sub.2O):
.delta.=1.88-1.95 (m, 2H), 1.97 (s, 3H), 2.88-2.92 (m, 2H), 3.16
(s, 12H), 3.27 (in, 2H) ppm. MS (ESI) m/z 180.04 (M-H).sup.-.
Step B: N-[3-(Chlorosulfonyl)propyl]acetamide (1)
[0424] Adapting a procedure or a variation thereof according to
Shue et al., Bioorg. Med. Chem. 1996, 6, 1709-1714, and Korolev et
al., Synthesis 2003, 383-388, a 500 mL round bottomed flask
equipped with a magnetic stir bar was charged with
tetramethylammonium N-acetylhomotaurate (1a) (9.1 g, 36 mmol),
phosphorus pentachloride (PCl.sub.5) (7.9 g, 37 mmol), and 200 mL
of anhydrous dichloromethane (200 mL). The solution was heated to
reflux overnight. The resulting mixture was washed twice with water
(100 mL) and brine (100 mL). The organic layer was dried over
magnesium sulfate (MgSO.sub.4), filtered, and the solvents removed
by evaporation under reduced pressure using a rotary evaporator to
provide 4.6 g (65% yield) of the title compound (1) as a light
yellow, viscous liquid. The crude material was of sufficient purity
to be used in the next steps. .sup.1H NMR (400 MHz, CDCl.sub.3):
.delta.=2.07 (s, 3H), 2.23-2.32 (m, 2H), 3.46-3.51 (m, 2H),
3.76-3.80 (m, 2H) ppm. MS (ESI) m/z 200.01 (M+H).sup.+. The
material contained various amounts of the cyclization product
2-acetyl-1,1-dioxo-1,2-thiazolidine as determined by .sup.1H NMR
spectroscopy and mass spectroscopy. .sup.1H NMR (400 MHz,
CDCl.sub.3): .delta.=2.37-2.44 (m, 5H), 3.41 (t, J=7.2 Hz, 2H),
3.84 (t, J=7.2 Hz, 2H) ppm. MS (ESI) m/z 164.01 (M+H).sup.+, 186.00
(M+Na).sup.+.
Description 2
General Procedure for the Preparation of Hydroxypivalic Acid Esters
(HPA-Esters) through Reaction of HPA with Alkylating Agents
Method A
[0425] A dry 500 mL round-bottomed flask equipped with a magnetic
stirring bar, a reflux condenser, and a rubber septum was charged
under an atmosphere of nitrogen with 7.09 g (60.0 mmol) of
3-hydroxy-2,2-dimethylpropanoic acid (hydroxypivalic acid, HPA) or
3-hydroxy-2-(hydroxymethyl)-2-methylpropanoic acid
(bis-hydroxypivalic acid, BHPA) and 19.55 g (60.0 mmol) of dried
and freshly powdered cesium carbonate (Cs.sub.2CO.sub.3). 150 mL of
anhydrous dimethylformamide (DMF) was added followed by 0.7-1.0
equivalents (40.0 to 60.0 mmol) of an appropriately substituted
alkyl halide. The reaction mixture was heated under an atmosphere
of nitrogen for overnight to ca. 50-70.degree. C. (oil bath)
(depending on the boiling point of the halide). The reaction
mixture was diluted with ethyl acetate, precipitates were filtered
off, and the filtrate was carefully diluted with a one molar (1.0
M) of hydrochloric acid (HCl). The aqueous phase was extracted
several times with ethyl acetate and the combined organic extracts
were washed with a saturated aqueous solution of sodium hydrogen
carbonate (NaHCO.sub.3). The organic solvents were removed under
reduced pressure using a rotary evaporator and the residue was
diluted in methyl tert-butyl ether (MTBE). The organic solution was
washed five times with water (to remove residual DMF), then brine,
dried over anhydrous magnesium sulfate (MgSO.sub.4), filtered and
the residual solvents removed under reduced pressure using a rotary
evaporator. Generally, the products were of sufficient purity to be
used directly in the next step without further purification or,
optionally, were purified by fractional distillation under reduced
pressure or silica gel column chromatography using ethyl
acetate/hexane mixtures as eluent.
Method B
[0426] rac-1-Acyloxyalkyl halides, i.e., chlorides, were either
commercially available or were prepared from the corresponding
aldehydes and carboxylic acid chlorides in the presence of
catalytic amounts of anhydrous zinc chloride (ZnCl.sub.2) adapting
literature known methods or variations thereof. As a typical
example, a 250 mL round bottomed flask equipped with a magnetic
stirring bar, an addition funnel, and a rubber septum was charged
under a nitrogen atmosphere with 100.0 mmol of the corresponding
aldehyde, a catalytic amount of anhydrous zinc chloride
(ZnCl.sub.2) (ca. 5-10 mol-%), and 100-300 mL of an inert solvent
such as dichloromethane (DCM). The solution was cooled to ca.
0.degree. C. (ice bath) and to 50.0 mmol of the corresponding
carboxylic acid chloride as a solution in DCM was added while
stirring. The reaction mixture was stirred at 0.degree. C. for
approximately three hours with gradual darkening of the mixture.
(Note: If the reaction is run for longer periods and with gradual
warming to room temperature, product yields and integrity will
become significantly lower after workup.). The solvents and excess
of volatile reagents were carefully removed under reduced pressure
using a rotary evaporator. The resulting crude reaction mixture was
directly pre-purified through a short plug filtration column using
n-pentane or hexanes as eluent followed by careful removal of the
solvents under slightly reduced pressure using a rotary evaporator.
Optionally, the crude reaction mixture was diluted with diethyl
ether (Et.sub.2O) and the solution washed with a saturated aqueous
solution of sodium hydrogen carbonate (NaHCO.sub.3), water, and
brine, dried over anhydrous magnesium sulfate (MgSO.sub.4),
filtered and carefully evaporated under reduced pressure using a
rotary evaporator to provide the desired product. Occasionally, the
products obtained by either pre-purification method were of
sufficient purity to be used directly in the next step without
further purification or, optionally, were purified further by
fractional distillation under reduced pressure or silica gel column
chromatography using diethyl ether (Et.sub.2O) or methyl tert-butyl
ether (MTBE) mixtures with pentane, hexanes, or heptane as eluent
(depending on the volatility of the title compound).
[0427] rac-1- Alkoxy- and aryloxycarbonyloxyalkyl halides, i.e.,
chlorides, were either commercially available or were prepared from
commercially available 1-chloroalkyl chloroformates and the
corresponding alcohols or phenols adapting methods known in the
literature or variations thereof. As a typical example, a 250 mL
round bottomed flask equipped with a magnetic stirring bar and a
rubber septum was charged under a nitrogen atmosphere with 10.0
mmol of the corresponding alcohol of phenol, 890 .mu.L (870 mg,
11.0 mmol) of anhydrous pyridine (Pyr) in 10-30 mL of an inert
solvent such as dichloromethane (DCM). The solution was cooled to
ca. 0.degree. C. (ice bath) and 12.0 mmol of the corresponding
rac-1-chloroalkyl chloroformate either in neat form or as a
concentrated solution in DCM was added while stirring. The reaction
mixture was stirred overnight with gradual warming to room
temperature. The solvents and volatile reagents were carefully
removed under reduced pressure using a rotary evaporator. The
residue was diluted with diethyl ether (Et.sub.2O) or methyl
tert-butyl ether (MTBE), washed with 0.1 molar hydrochloric acid
(HCl), water, and brine, and then dried over anhydrous magnesium
sulfate (MgSO.sub.4). After filtration and evaporation of the
solvents under reduced pressure using a rotary evaporator, the
desired compound was obtained. Generally, the products were of
sufficient purity to be used directly in the next step without
further purification or, optionally, were purified by fractional
distillation under reduced pressure or silica gel column
chromatography using diethyl ether (Et.sub.2O) or methyl tert-butyl
ether (MTBE) mixtures with pentane, hexanes, or heptane as eluent
(depending on the volatility of the title compound).
[0428] For the synthesis of acyloxyalkyl ester derivatives or
alkoxy- and aryloxycarbonyloxyalkyl ester derivatives, a 100 mL
round bottomed flask equipped with a magnetic stirring bar and a
rubber septum was charged under a nitrogen atmosphere with 709 mg
(6.0 mmol) of 3-hydroxy-2,2-dimethylpropanoic acid (hydroxypivalic
acid, HPA) or 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoic acid
(bis-hydroxypivalic acid, BHPA), and 2.0 equivalents (12.0 mmol) of
an appropriately substituted 1-chloro- or 1-iodoalkyl carboxylate
or an appropriately substituted 1-chloro- or 1-iodoalkyl alkyl- or
arylcarbonate. 2.09 mL (1.55 g, 12.0 mmol) of diethylisopropylamine
(DIEA, Hunigs base) were added neat. Optionally, 2 mL of anhydrous
1,2-dichloroethane was added to dissolve the reactants and to
facilitate stirring. The reaction mixture was heated to ca.
70.degree. C. and reacted overnight. Volatile reactants or solvents
were removed under reduced pressure using a rotary evaporator. The
residue was diluted with ethyl acetate (EtOAc) and water. After
extraction, the combined extracts were washed with brine and dried
over magnesium sulfate (MgSO.sub.4), filtered and the solvents
removed under reduced pressure using a rotary evaporator.
Optionally, the residues were used in the next step without further
purification or were purified using silica gel column
chromatography with ethyl acetate/hexane mixtures as eluent.
Example 2
Ethyl 3-hydroxy-2,2-dimethylpropanoate (2)
[0429] Following the general procedure for the synthesis of
hydroxypivalic ester derivatives of Description 2, 4.73 g (40.0
mmol) of 3-hydroxy-2,2-dimethylpropanoic acid (hydroxypivalic acid,
HPA) was reacted with 3.23 mL (6.24 g, 40.0 mmol) of iodoethane in
80 mL of DMF in the presence of 13.03 g (40.0 mmol) of
Cs.sub.2CO.sub.3. After work-up, 3.40 g (68% yield) of the title
compound (2) was obtained as a yellow liquid. The material was of
sufficient purity to be used in the next step without further
purification. .sup.1H NMR (400 MHz, CDCl.sub.3): .delta.=1.20 (s,
6H), 1.28 (t, J=7.2 Hz, 3H), 2.50-2.55 (br. m, 1H), 3.52-3.57 (br.
m, 2H), 4.16 (q, J=7.2 Hz, 2H) ppm.
Example 3
Methylethyl 3-hydroxy-2,2-dimethylpropanoate (3)
[0430] Following the general procedure for the synthesis of
hydroxypivalic ester derivatives of Description 2, 4.73 g (40.0
mmol) of 3-hydroxy-2,2-dimethylpropanoic acid (hydroxypivalic acid,
HPA) was reacted with 3.75 mL (4.92 g, 40.0 mmol) of 2-bromopropane
in 80 mL of DMF in the presence of 13.03 g (40.0 mmol) of
Cs.sub.2CO.sub.3. After work-up, 4.40 g (69% yield) of the title
compound (3) was obtained as a pale-yellow liquid. The material was
of sufficient purity to be used in the next step without further
purification. .sup.1H NMR (400 MHz, CDCl.sub.3): .delta.=1.18 (s,
6H), 1.25 (d, J=6.4Hz, 6H), 2.35-2.55 (br. m, 1H), 3.50-3.56 (br.
m, 2H), 5.02 (heptett, J=6.0 Hz, 1 H) ppm.
Example 4
Phenylmethyl 3-hydroxy-2,2-dimethylpropanoate (4)
[0431] Following the general procedure for the synthesis of
hydroxypivalic ester derivatives of Description 2, 7.09 g (60.0
mmol) of 3-hydroxy-2,2-dimethylpropanoic acid (hydroxypivalic acid,
HPA) was reacted with 5.94 mL (8.55 g, 50.0 mmol) of benzyl bromide
in 150 mL of DMF in the presence of 16.29 g (50.0 mmol) of
Cs.sub.2CO.sub.3. After work-up, 9.60 g (92% yield) of the title
compound (4) was obtained as a pale-yellow liquid. The material was
of sufficient purity to be used in the next step without further
purification. R.sub.f=0.44 (EtOAc/Hxn=1:2). .sup.1H NMR (400 MHz,
CDCl.sub.3): .delta.=1.21 (s, 6H), 2.34-2.41 (br. m, 1H), 3.55-3.59
(br. m, 2H), 3.82 (s, 3H), 5.09 (s, 2H), 6.86-6.90 (m, 2H),
7.24-7.32 (m, 2H) ppm.
Example 5
(4-Methoxyphenyl)methyl 3-hydroxy-2,2-dimethylpropanoate (5)
[0432] Adapting a procedure or a variation thereof according to
Zhou, et al., WO 99/51613, 20.0 g (143 mmol) of sodium
3-hydroxy-2,2-dimethylpropanoate was reacted with 19.7 mL (22.7 g,
145 mmol) of 4-methoxybenzyl chloride in anhydrous N-methyl
pyrrolidinone (NMP) as described in the general procedure of
Description 2. After work-up, the crude material was purified by
silica gel column chromatography using a mixture of ethyl acetate
(EtOAc) and hexane (Hxn) (EtOAc/Hxn=1:3) as eluent to provide 11.30
g (32% yield) of the title compound (5) as a pale-yellow liquid.
R.sub.f=0.38 (EtOAc/Hxn=1:2). .sup.1H NMR (400 MHz, CDCl.sub.3):
.delta.=1.21 (s, 6H), 2.34-2.41 (br. m, 1H), 3.55-3.59 (br. m, 2H),
3.82 (s, 3H), 5.09 (s, 2H), 6.86-6.90 (m, 2H), 7.24-7.32 (m, 2H)
ppm.
Example 6
Phenylmethyl 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoate (6)
[0433] Following the general procedure for the synthesis of
hydroxypivalic ester derivatives of Description 2, 3.35 g (25.0
mmol) of 3-hydroxy-2-(hydroxymethyl)-2-methylpropanoic acid
(bis-hydroxypivalic acid, BHPA) was reacted with 1.78 mL (2.57 g,
15.0 mmol) of benzylbromide in 50 mL of DMF in the presence of 6.52
g (15.0 mmol) of Cs.sub.2CO.sub.3. After work-up, 3.13 g (93%
yield) of the title compound (6) was obtained as colorless
crystals. The material was of sufficient purity to be used in the
next step without further purification. M.p.=71.6-72.8.degree. C.
.sup.1H NMR (400 MHz, CDCl.sub.3): .delta.=1.10 (s, 3H), 2.77-2.86
(br. m, 2H), 3.75 (d, J=11.6 Hz, 2H), 3.95 (d, J=11.2 Hz, 2H), 5.22
(s, 2H), 7.31-7.41 (m, 5H) ppm.
Example 7
rac-Ethoxycarbonyloxyethyl 3-hydroxy-2,2-dimethylpropanoate (7)
[0434] Following the general procedure for the synthesis of
acyloxyalkyl ester derivatives or alkoxy- and
aryloxycarbonyloxyalkyl derivatives of Description 2, 709 mg (6.0
mmol) of 3-hydroxy-2,2-dimethylpropanoic acid (hydroxypivalic acid,
HPA) was reacted with 1.83 g (12.0 mmol) of 1-chloroethyl ethyl
carbonate in the presence of 2.09 mL (1.55 g, 12.0 mmol) of
diethylisopropylamine (DIEA, Hunigs base). After work-up and
isolation, ca. 1.4 g (quant.) of the title compound (7) was
obtained as a colorless liquid. The material was of sufficient
purity to be used in the next step without further purification.
R.sub.f=0.44 (EtOAc/Hxn=1:2). .sup.1H NMR (400 MHz, CDCl.sub.3):
.delta.=1.18 (s, 3H), 1.21 (s, 3H), 1.32 (t, J=6.8 Hz, 3H), 1.53
(d, J=5.2 Hz, 3H), 2.35-2.52 (br. m, 1H), 3.48 (d, J=11.2 Hz, 1H),
3.60 (d, J=11.2 Hz, 1H), 4.22 (q, J=6.8 Hz, 2H), 6.70 (q, J=5.2 Hz,
1H) ppm. MS (ESI) m/z 257.00 (M+Na).sup.+.
Description 3
General Procedure for Synthesis of Acamprosate Neopentyl
Sulfonylester Prodrugs or Intermediates to Prodrugs
Method A
[0435] A 100 mL round-bottomed flask equipped with a magnetic stir
bar was charged at ca. 0.degree. C. (icebath) with
N-[3-(chlorosulfonyl)propyl]acetamide (1) (ca. 300 mg, 1.5 mmol),
the corresponding functionalized neopentyl alcohol (3.0 mmol), and
10 mL of dichloromethane (DCM). To the solution was added 209 .mu.L
of triethylamine (TEA, Et.sub.3N) (152 mg, 2.0 mmol,) and
4-(N,N-dimethyl)aminopyridine (DMAP) (183 mg, 1.5 mmol). The
reaction mixture was stirred overnight at room temperature. Upon
completion of the reaction, dichloromethane was evaporated and the
residue was diluted with ethyl acetate (EtOAc) and water. The
aqueous layer was acidified with a one molar (1.0 M) hydrochloric
acid (HCl). After vigorous mixing followed by phase separation, the
aqueous layer was extracted twice more with ethyl acetate. The
combined organic extracts were successively washed with a saturated
aqueous sodium hydrogencarbonate (NaHCO.sub.3) solution, brine, and
then dried over MgSO.sub.4. After filtration, the solvent was
evaporated under reduced pressure using a rotary evaporator. The
residue was dissolved in a mixture of ca. 60% (v/v)
acetonitrile/water and the solution filtered through a 0.2-.mu.m
nylon syringe filter and purified by mass-guided preparative HPLC.
After lyophilization of the solvents, the corresponding acamprosate
neopentyl sulfonylester prodrug was obtained as a colorless oil or
solid. Alternatively, acamprosate neopentyl sulfonylester prodrugs
were purified by silica gel chromatography using ethyl
acetate/hexane or ethyl acetate/methanol mixtures as eluent
followed by removal of the solvents under reduced pressure using a
rotary evaporator.
Method B
[0436] Operational (synthesis and work-up) procedures in Method B
were identical to the ones described in Method A. The molar ratios
of the reactants were similar but
N-[3-(chlorosulfonyl)propyl]acetamide (1) the commercially
available 3-chloropropylsulfonyl chloride, a precursor to
acamprosate prodrugs, was employed for the synthesis of suitable
neopentyl sulfonyl ester intermediates. Acamprosate neopentyl
sulfonylester intermediates were generally purified by silica gel
chromatography using ethyl acetate (EtOAc) or methyl tert-butyl
ether (MTBE) and hexane or n-heptane mixtures as eluent followed by
removal of the solvents under reduced pressure using a rotary
evaporator.
Example 8
Methyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
(8)
[0437] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs of Description 3
(Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1) (ca. 1.00 g,
5.0 mmol), dissolved in 8 mL of dichloromethane, was reacted with
397 mg (3.0 mmol) of commercially available methyl
3-hydroxy-2,2-dimethylpropanoate (2) in the presence of 697 .mu.L
of triethylamine (506 mg, 5.0 mmol) and 611 mg (5.0 mmol) of DMAP.
After aqueous work-up and purification by mass-guided preparative
HPLC, 205 mg (23% yield) of the title compound (8) was obtained as
a colorless, viscous oil. .sup.1H NMR (400 MHz, DMSO-d.sup.6):
.delta.=1.18 (s, 6H), 1.73-1.82 (m, 5H), 3.12 (q, J=5.6 Hz, 2H),
3.29-3.36 (m, 2H), 3.64 (s, 3H), 4.18 (s, 2H), 7.90 (br. t, J=5.2
Hz, 1H) ppm. MS (ESI) m/z 296.08 (M+H).sup.+, 318.09
(M+Na).sup.+.
Example 9
Ethyl 3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
(9)
[0438] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs of Description 3
(Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1) (ca. 500 mg,
2.5 mmol) dissolved in 8 mL of dichloromethane was reacted with 585
mg (4.0 mmol) of ethyl 3-hydroxy-2,2-dimethylpropanoate (2) in the
presence of 348 .mu.L of triethylamine (253 mg, 2.5 mmol) and 305
mg (2.5 mmol) of DMAP. Following aqueous work-up and purification
by mass-guided preparative HPLC, 208 mg (27% yield) of the title
compound (9) was obtained as a colorless, viscous oil. .sup.1H NMR
(400 MHz, CDCl.sub.3): .delta.=1.28 (s, 6H), 1.29 (t, J=7.2 Hz,
3H), 2.01 (s, 3H), 2.04-2.11 (m, 2H), 3.17-3.22 (m, 2H), 3.40 (q,
J=6.4 Hz, 2H), 4.17 (q, J=7.2 Hz, 2H), 4.20 (s, 2H), 5.97-6.04 (br.
m, 1H) ppm. MS (ESI) m/z 310.10 (M+H).sup.+, 332.04
(M+Na).sup.+.
Example 10
Methylethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
(10)
[0439] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs of Description 3
(Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1) (ca. 500 mg,
2.5 mmol), dissolved in 8 mL of dichloromethane, was reacted with
585 mg (4.0 mmol) of methylethyl 3-hydroxy-2,2-dimethylpropanoate
(3) in the presence of 348 .mu.L of triethylamine (253 mg, 2.5
mmol) and 305 mg (2.5 mmol) of DMAP. After aqueous work-up and
purification by mass-guided preparative HPLC, 192 mg (24% yield) of
the title compound (10) was obtained as a colorless, viscous oil.
.sup.1H NMR (400 MHz, CDCl.sub.3): .delta.=1.25-1.28 (m, 12H), 2.01
(s, 3H), 2.04-2.12 (m, 2H), 3.17-3.22 (m, 2H), 3.41 (q, J=6.8 Hz,
2H), 4.19 (s, 2H), 5.01 (heptett, J=6.4 Hz, 1H), 5.94-6.02 (br. m,
1H) ppm. MS (ESI) m/z 324.12 (M+H).sup.+, 346.06 (M+Na).sup.+.
Example 11
Phenylmethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
(11)
[0440] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs of Description 3
(Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1) (ca. 8.98 g,
45.0 mmol) dissolved in 150 mL of dichloromethane was reacted with
10.41 g (50.0 mmol) of phenylmethyl
3-hydroxy-2,2-dimethylpropanoate (4) in the presence of 6.97 mL of
triethylamine (5.06 g, 50 mmol) and 6.11 g (50 mmol) of DMAP. After
aqueous work-up, the crude material was purified by silica gel
column chromatography using mixtures of ethyl acetate (EtOAc) and
hexane (Hxn) as eluent
(EtOAc/Hxn=6:1.fwdarw.9:1.fwdarw.14:1.fwdarw.100% EtOAc) to provide
5.50 g (33% yield) of the title compound (11) as a colorless,
viscous oil. R.sub.f=0.59 (EtOAc/MeOH=19:1). .sup.1H NMR (400 MHz,
CDCl.sub.3): .delta.=1.31 (s, 6H), 1.92-2.01 (m, 5H), 3.06-3.12 (m,
2H), 3.32 (q, J=6.4 Hz, 2H), 4.21 (s, 2H), 5.16 (s, 2H), 5.78-5.84
(br. m, 1H), 7.31-7.41 (m, 5H) ppm. MS (ESI) m/z 372.13
(M+H).sup.+, 394.08 (M+Na).sup.+.
Example 12
3-{[3-(Acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoic acid
(12)
[0441] A 100 mL round-bottomed flask equipped with a magnetic
stirring bar and a three-way adapter connected to a hydrogen filled
balloon at ca. 15 psi was charged with 505 mg (1.36 mmol) of
phenylmethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate (11)
and 400 mg of 10 wt-% palladium on activated carbon. Twenty-five
(25) mL of anhydrous ethanol (EtOH) was added and the atmosphere
was exchanged to hydrogen with five alternating evacuation/refill
cycles. The reaction mixture was stirred for two hours at room
temperature and then filtered through a short plug of Celite.RTM..
The filter medium was washed several times with EtOH. After partial
evaporation of the solvent under reduced pressure using a rotary
evaporator, the residual solution was filtered through a 0.2 .mu.M
nylon syringe filter and evaporated under reduced pressure to
provide 383 mg (quant.) of the title compound (12) as a colorless
oil. .sup.1H NMR (400 MHz, DMSO-d.sup.6): .delta.=1.15 (s, 6H),
1.74-1.82 (m, 5H), 3.08-3.16 (m, 2H), 3.29-3.37 (m, 2H), 4.15 (s,
2H), 7.90 (t, J=5.6 Hz, 1H), 12.63 (br. s, 1H) ppm. MS (ESI) m/z
282.13 (M+H).sup.+, 304.00 (M+Na).sup.+, 280.03 (M-H).sup.-.
Example 13
(4-Methoxyphenyl)methyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
(13)
[0442] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs of Description 3
(Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1) (ca. 500 mg,
2.5 mmol) dissolved in 8 mL of dichloromethane was reacted with 715
mg (3.0 mmol) of (4-methoxyphenyl)methyl
3-hydroxy-2,2-dimethylpropanoate (5) in the presence of 348 .mu.L
of triethylamine (253 mg, 2.5 mmol) and 305 mg (2.5 mmol) of DMAP.
After aqueous work-up, the crude product was purified by silica gel
column chromatography using a mixture of ethyl acetate (EtOAc) and
methanol (MeOH) as eluent (EtOAc/MeOH=19:1) to provide 150 mg (15%
yield) of the title compound (13) as a colorless, viscous oil.
R.sub.f=0.32 (EtOAc). .sup.1H NMR (400 MHz, CDCl.sub.3):
.delta.=1.28 (s, 6H), 1.93-2.02 (m, 5H), 3.06-3.12 (m, 2H), 3.34
(q, J=6.4 Hz, 2H), 3.82 (s, 3H), 4.19 (s, 2H), 5.09 (s, 2H),
5.81-5.88 (br. m, 1H), 6.87-6.92 (m, 2H), 7.26-7.30 (m, 2H) ppm. MS
(ESI) m/z 402.14 (M+H).sup.+, 424.09 (M+Na).sup.+.
Example 14
Phenylmethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2-({[3-(acetylamino)propyl]sulfony-
loxy}methyl)-2-methylpropanoate (14)
[0443] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs of Description 3
(Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1) (ca. 1.00 g,
5.0 mmol) dissolved in 15 mL of dichloromethane was reacted with
300 mg (1.34 mmol) of phenylmethyl
3-hydroxy-2-(hydroxymethyl)-2-methylpropanoate (6) in the presence
of 697 .mu.L of triethylamine (506 mg, 5.0 mmol) and 611 mg (5.0
mmol) of DMAP. After aqueous work-up and purification by
mass-guided preparative HPLC, 262 mg (36% yield) of the title
compound (14) was obtained as a colorless, viscous oil. .sup.1H NMR
(400 MHz, CDCl.sub.3): .delta.=1.33 (s, 3H), 1.97-2.06 (m, 10H),
3.14-3.19 (m, 4H), 3.32-3.39 (m, 4H), 4.30 (d, J=9.6 Hz, 2H), 4.42
(d, J=10.0 Hz, 2H), 5.20 (s, 2H), 6.20 (br. t, J=6.0 Hz, 2H),
7.32-7.41 (m, 5H) ppm. MS (ESI) m/z 551.24 (M+H).sup.+, 574.09
(M+Na).sup.+.
Example 15
rac-Phenylmethyl
2-({[3-(acetylamino)propyl]sulfonyloxy}-methyl)-3-hydroxy-2-methylpropano-
ate (15)
[0444] The corresponding mono-sulfonylester derivative (15) was
also isolated from the crude reaction product of Example 14 by
mass-guided preparative HPLC and was obtained as a colorless oil.
.sup.1H NMR (400 MHz, CDCl.sub.3): .delta.=1.27 (s, 3H), 1.97-2.08
(m, 5H), 3.11-3.20 (m, 2H), 3.31-3.38 (m, 2H), 3.72 (d, J=10.8 Hz,
1H), 3.87 (d, J=11.2 Hz, 1H), 4.34 (d, J=9.6 Hz, 1H), 4.47 (d,
J=10.0 Hz, 1H), 5.19 (s, 2H), 5.83-5.90 (br. m, 1H), 7.31-7.41 (m,
5H) ppm. MS (ESI) m/z 388.10 (M+H).sup.+, 410.00 (M+Na).sup.+.
Example 16
rac-Ethoxycarbonyloxyethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
(16)
[0445] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs of Description 3
(Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1) (ca. 1.00 g,
5.0 mmol) dissolved in 15 mL of dichloromethane was reacted with
ca. 1.4 g (6.0 mmol) of rac-ethoxycarbonyloxyethyl
3-hydroxy-2,2-dimethylpropanoate (7) in the presence of 697 .mu.L
of triethylamine (506 mg, 5.0 mmol) and 611 mg (5.0 mmol) of DMAP.
After aqueous work-up, the crude material was purified by silica
gel column chromatography using mixtures of ethyl acetate (EtOAc)
and hexane (Hxn) as eluent (EtOAc/Hxn=4:1.fwdarw.9:1.fwdarw.100%
EtOAc) to provide 434 mg (22% yield) of the title compound (16) as
a colorless, viscous oil. R.sub.f=0.24 (EtOAc/Hxn=4:1). .sup.1H NMR
(400 MHz, CDCl.sub.3): .delta.=1.29 (s, 6H), 1.34 (t, J=7.2 Hz,
3H), 1.55 (d, J=5.6 Hz, 3H), 2.01 (s, 3H), 2.03-2.11 (m, 2H),
3.16-3.24 (m, 2H), 3.35-3.46 (m, 2H), 4.15-4.28 (m, 4H), 5.40-6.40
(br. m, 1H), 6.76 (q, J=5.6 Hz, 1H) ppm. MS (ESI) m/z 398.01
(M+H).sup.+, 419.95 (M+Na).sup.+.
Example 17
rac-Methylethoxycarbonyloxyethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
(17)
[0446] The title compound (17), an oxidative degradation product
produced during preparation of pantoic acid based neopentyl
sulfonyl ester acamprosate prodrugs, was isolated following
mass-guided preparative HPLC purification as a colorless, viscous
oil (57 mg). R.sub.f=0.15 (EtOAc/Hxn=4:1). .sup.1H NMR (400 MHz,
CDCl.sub.3): .delta.=1.29 (s, 6H), 1.327/1.330 (2d, superimposed,
J=6.4 Hz, 6H), 1.55 (d, J=5.6 Hz, 3H), 2.07 (s, 3H), 2.03-2.11 (m,
2H), 3.18-3.23 (m, 2H), 3.34-3.47 (m, 2H), 4.16 (d, J=9.6 Hz, 1H),
4.21 (d, J=9.2 Hz, 1H), 4.84-4.94 (m, 1H), 5.95-6.01 (br. m, 1H),
6.75 (q, J=5.6 Hz, 1H) ppm. MS (ESI) m/z 412.0 (M+H).sup.+, 434.0
(M+Na).sup.+.
Example 18
2-Morpholin-4-ylethyl
3-{[3-(acetylamino)propyl]-sulfonyloxy}-2,2-dimethylpropanoate
Hydrochloride (18)
Step A: 2,2-Dimethyl-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoic
acid (18a)
[0447] A 2 L round bottomed flask equipped with a magnetic stir bar
was charged with 11.8 g (100 mmol) of
3-hydroxy-2,2-dimethylpropanoic acid and the acid dissolved in 1 L
of anhydrous dichloromethane (DCM). Tert-butyl dimethylchlorosilane
(31.7 g, 210 mmol) and imidazole (14.3 g, 210 mmol) was added while
stirring. The reaction was monitored by TLC. After the starting
material was completely consumed the white precipitate was filtered
off and the solvent removed under reduced pressure using a rotary
evaporator. The residue was dissolved in 500 mL of diethyl ether
(Et.sub.2O). The mixture was stirred for two hours and the
colorless precipitate filtered off. After removing diethyl ether
under reduced pressure using a rotary evaporator, the residue was
dissolved in 600 mL of a mixture of water and acetonitrile (1:1).
8.0 g (200 mmol) of sodium hydroxide was added to the solution and
the mixture was stirred overnight at room temperature. The reaction
was acidified with a one normal (1N) aqueous solution of hydrogen
chloride (HCl) and extracted with ethyl acetate. The combined
organic extracts were washed with water and brine, dried over
magnesium sulfate (MgSO.sub.4), filtered, and the solvents removed
under reduced pressure using a rotary evaporator. The residue was
purified by silica gel chromatography using a mixture of ethyl
acetate (EtOAc) and hexane (Hxn) (EtOAc/Hxn=1:4) as eluent to
provide 23 g (quant.) of the title compound (18a) as a colorless
liquid. R.sub.f=0.58 (EtOAc/Hexane =1:4). .sup.1H NMR (400 MHz,
CDCl.sub.3): .delta.=0.07 (s, 6H), 0.90 (s, 9H), 1.19 (s, 6H), 3.60
(s, 2H) ppm. MS (ESI) m/z 233.01 (M+H).sup.+.
Step B: 2-Morpholin-4-ylethyl
2,2-dimethyl-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate
(18b)
[0448] To a stirred solution of
2,2-dimethyl-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoic acid
(18a) (2.3 g, 10.0 mmol) in 100 mL of anhydrous dichloromethane
(DCM) in a 250 mL round-bottomed flask equipped with a magnetic
stir bar was added N,N'-dicyclohexylcarbodiimide (2.3 g, 11.0
mmol), N-(2-hydroxyethyl)morpholine (1.2 g, 9.0 mmol) and 0.15 g
(1.1 mmol) of 4-N,N-dimethylaminopyridine (DMAP). The reaction was
stirred overnight at room temperature. The colorless precipitate
was filtered off and the solvent removed under reduced pressure
using a rotary evaporator. The residue was purified by silica gel
chromatography using a mixture of ethyl acetate (EtOAc) and hexane
(Hxn) (EtOAc/Hxn=1:1) as eluent to provide 0.53 g (17% yield) of
the title compound (18b) as a colorless solid. R.sub.f=0.4
(EtOAc/Hxn=1:1). .sup.1H NMR (400 MHz, CDCl.sub.3): .delta.=0.04
(s, 6H), 0.88 (s, 9H), 1.16 (s, 6H), 2.50-2.54 (m, 4H), 2.63 (t,
J=6.0 Hz, 2H), 3.57 (s, 2H), 3.68-3.73 (m, 4H), 4.21 (t, J=6.0 Hz,
2H) ppm. MS (ESI) m/z 346.26 (M+H).sup.+.
Step C: 2-Morpholin-4-ylethyl 3-hydroxy-2,2-dimethylpropanoate
(18c)
[0449] Adapting a procedure, or a variation thereof according to
Pirrung et al., Bioorg. Med. Chem. Lett., 1994, 4, 1345, 0.73 g of
triethylamine trihydrofluoride (4.5 mmol) was added to a solution
of 2-morpholin-4-ylethyl
2,2-dimethyl-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate (18b)
(0.52 g, 1.5 mmol) in 10 mL of anhydrous tetrahydrofuran (THF)
while stirring. The reaction mixture was stirred overnight at
50.degree. C. After the starting material was completely consumed,
the solvent was removed under reduced pressure using a rotary
evaporator. The residue was purified by silica gel chromatography
using a mixture of ethyl acetate (EtOAc) and methanol (MeOH)
(EtOAc/MeOH=4:1) as eluent to provide 330 mg (95% yield) of the
title compound (18c). R.sub.f=0.29 (EtOAc). .sup.1H NMR (400 MHz,
CDCl.sub.3): .delta.=1.21 (s, 6H), 2.47-2.54 (m, 4H), 2.58-2.63 (m,
2H), 3.54 (s, 2H), 3.69-3.73 (m, 4H), 4.33-4.37 (m, 2H) ppm. MS
(ESI) m/z 232.10 (M+H).sup.+.
Step D: 2-Morpholin-4-ylethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
Hydrochloride (18)
[0450] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs of Description 3
(Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1) (0.43 g, 2.1
mmol) dissolved in 10 mL of dichloromethane (DCM) was reacted with
2-morpholin-4-ylethyl 3-hydroxy-2,2-dimethylpropanoate (18c) (0.33
g, 1.43 mmol) in the presence of 0.30 mL of triethylamine (0.22 g,
2.1 mmol) and 24 mg (0.2 mmol) of DMAP. After mass-guided
preparative HPLC purification and lyophilization in the presence of
a slight excess of a one molar (1.0 M) hydrochloric acid (HCl), 60
mg (10% yield) of the title compound (18) was obtained as a
colorless solid. .sup.1H NMR (400 MHz, CDCl.sub.3): .delta.=1.29
(s, 6H), 2.01 (s, 3H), 2.02-2.10 (m, 2H), 2.62-2.66 (m, 4H), 2.76
(t, J=6.0 Hz, 2H), 3.17-3.22 (m, 2H), 3.37-3.43 (m, 2H), 3.72-3.77
(m, 4H), 4.20 (s, 2H), 4.30 (t, J=6.0 Hz, 2H), 6.12-6.20 (m, 1 H)
ppm. MS (ESI) m/z 395.10 (M+H).sup.+.
Example 19
3-Pyridylmethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
Hydrochloride (19)
Step A: 2-Pyridylmethyl
2,2-dimethyl-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate
(19a)
[0451] One (1.0) mL of 3-pyridinemethanol (1.2 g, 11.0 mmol) and
4-N,N-dimethylaminopyridine (DMAP) (0.15 g, 1.1 mmol) were added to
a solution of
2,2-dimethyl-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoic acid
(18a) (Example 18, Step A) (2.3 g, 10.0 mmol) in 100 mL of
anhydrous dichloromethane (DCM) in a 250 mL round-bottomed flask
equipped with a magnetic stir bar was added
N,N'-dicyclohexylcarbodiimide (2.3 g, 11.0 mmol) while stirring.
The reaction mixture was stirred overnight at room temperature. The
colorless precipitate was then filtered off and the solvent removed
under reduced pressure using a rotary evaporator. The residue was
purified by silica gel chromatography using a mixture of ethyl
acetate (EtOAc) and hexanes (Hxn) (EtOAc/Hxn=1:2) as eluent to
provide 1.2 g (37% yield) of the title compound (19a) as colorless
liquid. R.sub.f=0.43 (EtOAc/Hxn=1:2). .sup.1H NMR (400 MHz,
CDCl.sub.3): .delta.=0.01 (s, 6H), 0.86 (s, 9H), 1.19 (s, 6H), 3.60
(s, 2H), 5.13 (s, 2H), 7.24-7.30 (m, 1H), 7.65-7.69 (m, 1H),
8.55-8.57 (m, 1H), 8.59-8.61 (m, 1H) ppm. MS (ESI) m/z 324.16
(M+H).sup.+.
Step B: 3-Pyridylmethyl 3-hydroxy-2,2-dimethylpropanoate (19b)
[0452] Adapting a procedure, or a variation thereof according to
Pirrung et al., Bioorg. Med. Chem. Lett., 1994, 4, 1345, 1.77 g
(11.0 mmol) of triethylamine trihydrofluoride was added to a
stirred solution of 3-pyridylmethyl
2,2-dimethyl-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate (19a)
(1.2 g, 3.7 mmol) in 30 mL of anhydrous tetrahydrofuran (THF). The
reaction mixture was stirred overnight at 50.degree. C. After the
starting material was completely consumed, the solvent was removed
under reduced pressure using a rotary evaporator. The residue was
purified by silica gel chromatography using a mixture of ethyl
acetate (EtOAc) and methanol (MeOH) (EtOAc/MeOH=10:1) as an eluent
to provide 800 mg (quant.) of the title compound (19b) as a
colorless solid. R.sub.f=0.34 (EtOAc). .sup.1H NMR (400 MHz,
CDCl.sub.3): .delta.=1.23 (s, 6H), 2.38-2.52 (br. m, 1H), 3.60 (s,
2H), 5.17 (s, 2H), 7.25-7.33 (m, 1H), 7.65-7.69 (m, 1H), 8.56-8.59
(m, 1 H), 8.60-8.62 (m, 1 H) ppm. MS (ESI) m/z 209.99
(M+H).sup.+.
Step C: 3-Pyridylmethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-dimethylpropanoate
Hydrochloride (19)
[0453] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs of Description 3
(Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1) (0.76 g, 3.8
mmol) dissolved in 20 mL of dichloromethane was reacted with
3-pyridylmethyl 3-hydroxy-2,2-dimethylpropanoate (19b) (0.4 g, 1.9
mmol) in the presence of 0.53 mL of triethylamine (0.38 g, 3.8
mmol) and 50 mg (0.4 mmol) of DMAP. After mass-guided preparative
HPLC purification and lyophilization in the presence of a slight
excess of a one molar (1.0 M) hydrochloric acid (HCl), 370 mg (47%
yield) of the title compound (19) was obtained. .sup.1H NMR (400
MHz, MeOH-d.sup.4): .delta.=1.31 (s, 6H), 1.97-2.05 (m, 2H), 2.15
(s, 3H), 3.29-3.34 (m, 2H), 4.41 (t, J=6.8 Hz, 2H), 4.30 (s, 2H),
5.42 (s, 2H), 8.12-8.16 (m, 1H), 8.69-8.73 (m, 1H), 8.85-8.87 (m,
1H), 8.96-8.97 (m, 1H) ppm. MS (ESI) m/z 373.08 (M+H).sup.+.
Example 20
rac-Methyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2-[(tert-butoxy)carbonyl-
amino]-2-methylpropanoate (20)
Step A: rac-Methyl 2-amino-3-hydroxy-2-methylpropanoate
Hydrochloride (20a)
[0454] Adapting a procedure or variation thereof according to
Clemens et al., Bioorg. Med. Chem. Lett. 2004, 14, 4903-4906, a 500
mL round-bottomed flask equipped with a magnetic stirring bar and a
reflux condenser was charged with commercially available
2-amino-3-hydroxy-2-methylpropanoic acid (1.67 g, 14.0 mmol) and
200 mL of anhydrous methanol (MeOH). To the stirred solution was
added 110 .mu.L (0.18 g, 1.5 mmol) of neat thionyl chloride
(SOCl.sub.2) and the reaction mixture was heated to reflux
overnight. The solvent was then removed under reduced pressure
using a rotary evaporator. The residue was purified by mass-guided
preparative HPLC to provide 550 mg (30% yield) of the title
compound (20a) as a colorless solid. .sup.1H NMR (400 MHz,
MeOH-d.sup.4): .delta.=1.52 (s, 3H), 3.38 (s, 3H), 3.68 (d,
J.sub.gem=11.2 Hz, 1H), 3.97 (d, J.sub.gem=11.2 Hz, 1H) ppm. MS
(ESI) m/z 133.94 (M+H).sup.+. The analytical data for the compound
was consistent with that given in then literature.
Step B: rac-Methyl
2-[(tert-butoxy)carbonylamino]-3-hydroxy-2-methylpropanoate
(20b)
[0455] Adapting a procedure or variation thereof according to
Clemens et al., Bioorg. Med. Chem. Lett. 2004, 14, 4903-4906, a 500
mL round-bottomed flask equipped with a magnetic stir bar was
charged with (2.5 g, 15.0 mmol) of methyl
2-amino-3-hydroxy-2-methylpropanoate hydrochloride (20a) and 200 mL
of a mixture of acetonitrile (H.sub.3CCN) and water (v/v=1:1). To
the stirred solution was added sodium hydrogencarbonate
(NaHCO.sub.3) (2.8 g, 45.0 mmol) and 6.5 g (30.0 mmol) of
di-tert-butyl dicarbonate (di-tert-butyl pyrocarbonate, Boc.sub.2O)
and the reaction mixture was stirred overnight at room temperature.
After the starting material was completely consumed, the reaction
was diluted with water and the aqueous phase extracted with ethyl
acetate (EtOAc). The organic extracts were washed in brine, dried
over anhydrous magnesium sulfate (MgSO.sub.4), filtered, and the
solvents removed under reduced pressure using a rotary evaporator.
The residue was purified by silica gel chromatography using ethyl
acetate (EtOAc) as eluent to provide 0.8 g (24% yield) of the title
compound (20b) as a colorless oil. R.sub.f=0.51 (EtOAc). .sup.1H
NMR (400 MHz, CDCl.sub.3): .delta.=1.46 (s, 9H), 1.49 (s, 3H),
3.77-3.79 (m, 4H), 4.00 (d, J=11.6 Hz, 1H), 5.29 (br. s, 1H) ppm.
MS (ESI) m/z 234.06 (M+H).sup.+. The analytical data for the
compound was consistent with that given in the literature.
Step C: Methyl
3-{[3-(Acetylamino)propyl]sulfonyloxy}-2-[(tert-butoxy)carbonylamino]-2-m-
ethylpropanoate (20)
[0456] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs of Description 3
(Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1) (ca. 0.4 g,
2.0 mmol) dissolved in 20 mL of dichloromethane was reacted with
methyl 2-[(tert-butoxy)carbonylamino]-3-hydroxy-2-methylpropanoate
(20b) (0.25 g, 1.1 mmol) in the presence of 0.28 mL of
triethylamine (0.20 g, 2.0 mmol) and 24 mg (0.2 mmol) of DMAP.
After mass-guided preparative HPLC purification, 210 mg (49% yield)
of the title compound (20) was obtained as a clear oil. .sup.1H NMR
(400 MHz, CDCl.sub.3): .delta.=1.45 (s, 9H), 1.54 (s, 3H), 2.01 (s,
3H), 2.04-2.09 (m, 2H), 3.18 (t, J=7.2 Hz, 2H), 3.39 (q, J=5.6 Hz,
2H), 3.80 (s, 3H), 4.57 (d, J=10.4 Hz, 1H), 4.68 (br. d, J=10.4 Hz,
1H), 5.40 (br. s, 1H), 5.94-6.00 (br. m, 1H) ppm. MS (ESI) m/z
397.03 (M+H).sup.+.
Example 21
Methyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2-amino-2-methylpropanoate
Hydrochloride (21)
[0457] To a stirred solution of methyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2-[(tert-butoxy)carbonylamino]-2-m-
ethylpropanoate (20) (0.13 g, 0.33 mmol) in 5 mL of dichloromethane
(DCM) was added 5 mL of trifluroacetic acid (F.sub.3CO.sub.2H,
TFA). The reaction was stirred at room temperature for two hours.
The solvent was then removed under reduced pressure using a rotary
evaporator. The residue was further purified using mass-guided
preparative HPLC. Removal of the solvent by lyophilization in the
presence of a slight excess of an one molar (1.0 M) hydrochloric
acid (HCl) afforded 60 mg (55% yield) of the title compound (21).
.sup.1H NMR (400 MHz, MeOH-d.sup.4): .delta.=1.66 (s, 3H),
2.05-2.13 (m, 2H), 2.14 (s, 3H), 3.42-3.48 (m, 4H), 3.93 (s, 3H),
4.47 (d, J=10.8 Hz, 2H), 4.70 (d, J=11.2 Hz, 2H) ppm. MS (ESI) m/z
297.03 (M+H).sup.+.
Example 22
Ethyl 3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-diethoxypropanoate
(22)
Step A : rac-Ethyl glycerate (22a)
[0458] Adapting a procedure according to Choi et al., Bioorg. Med.
Chem. 1996, 4, 2105-2114, a 1,000 mL round bottomed flask equipped
with a magnetic stirring bar was charged with 15.65 g (99.0 mmol)
of potassium permanganate (KMnO.sub.4). The oxidant was dissolved
in 150 mL of water and 300 mL of acetone and the reaction mixture
was cooled to ca. -78.degree. C. using a dry ice/acetone bath. 9.75
mL of ethyl acrylate (9.01 g, 90.0 mmol) was slowly added while
stirring at -78.degree. C. The reaction mixture was slowly warmed
to 0.degree. C. The inorganic salts were removed by filtration and
the filter residue was washed with 150 mL of acetone. The combined
filtrates were concentrated under reduced pressure at temperatures
below 40.degree. C. using a rotary evaporator. The product was
extracted with ethyl acetate (3.times.200 mL) and the combined
extracts were dried over anhydrous sodium sulfate
(Na.sub.2SO.sub.4). After filtration, the solvent was removed under
reduced pressure using a rotary evaporator to provide 4.2 g (35%
yield) of the title compound (22a) as a clear, colorless oil. The
material was of sufficient purity to be used in the next step
without further purification. R.sub.f=0.60 (MeOH/CHCl.sub.3=3:7).
.sup.1H NMR (CDCl.sub.3, 400 MHz): .delta.=1.32 (t, J=7.2 Hz, 3H),
2.30-2.70 (br. m, 1H), 3.30-3.60 (br. m, 1H), 3.85 (dd, J=11.6, 3.6
Hz, 1H), 3.91 (dd, J=11.2, 2.8 Hz, 1H), 4.23-4.32 (m, 3H) ppm. MS
(ESI) m/z 135.07 (M+H).sup.+. The analytical data for the compound
was consistent with the data given in the literature.
Step B: rac-Ethyl
2-hydroxy-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate (22b)
[0459] Adapting procedures or variations thereof according to Shin
et al., J. Org. Chem, 2000, 65, 7667-7675 and Parkkari et al.,
Bioorganic Med. Chem. Lett. 2004, 14, 3231-3234, a 250 mL
round-bottomed flask equipped with a magnetic stirring bar was
charged with 1.0 g (7.45 mmol) of rac-ethyl glycerate (22a) and the
material dissolved in 20 mL of anhydrous dichloromethane (DCM).
Imidazole (0.51 g, 7.45 mmol), 7.45 mL of a one molar (1.0 M
solution of tert-butyl dimethylchlorosilane in DCM, and 0.4 g, 2.98
mmol of 4-(N,N-dimethylamino)pyridine (DMAP) were added. The
reaction mixture was stirred overnight at room temperature. The
reaction mixture was diluted with 100 mL of DCM and washed twice
with water and brine. The combined organic extracts were dried over
anhydrous magnesium sulfate (MgSO.sub.4). After filtration, the
solvent was removed under reduced pressure using a rotary
evaporator to provide 1.8 g (97% yield) of the title compound (22b)
as a clear oil that was of sufficient purity to be used in the next
step without further purification. R.sub.f=0.50 (EtOAc/Hxn=1:1).
.sup.1H NMR (CDCl.sub.3, 400 MHz): .delta.=0.05 (s, 3H), 0.06 (s,
3H), 0.87 (s, 9H), 1.30 (t, J=7.2 Hz, 3H), 2.98-3.08 (br. m, 1H),
3.85 (dd, J=10.0, 3.2 Hz, 1H), 3.92 (dd, J=10.4, 3.2 Hz, 1H),
4.17-4.20 (m, 1H), 4.24 (q, J=7.6 Hz, 2H) ppm. MS (ESI) m/z =249.07
(M+H).sup.+. The analytical data for the compound was consistent
with the proposed structure of the compound as described in
Carreiro, et al., ES 2006959.
Step C: Ethyl 2-oxo-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate
(22c)
[0460] Adapting procedures or variations thereof according to Dess
et al., J. Am. Chem. Soc. 1991, 113, 7277-7287, 1.6 g (3.77 mmol)
of 1,1,1-tris(acetyloxy)-1,1-dihydro-1,2-benziodoxol-3-(1H)-one
(Dess-Martin periodinane) was added to a solution of 0.8 g (3.22
mmol) of ethyl
2-hydroxy-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate (22b) in
15 mL of anhydrous dichloromethane while stirring at ca. 0.degree.
C. (ice bath). The reaction mixture was stirred for six hours at
room temperature. The solvent was removed under reduced pressure
using a rotary evaporator and the residue diluted with 100 mL of
diethyl ether and washed twice with a saturated sodium bicarbonate
(NaHCO.sub.3) solution and subsequently with an aqueous 10 wt-%
solution of sodium thiosulfate (Na2S.sub.2O.sub.3). The combined
organic extracts were dried over anhydrous magnesium sulfate
(MgSO.sub.4). The solvents were removed under reduced pressure
using a rotary evaporator. The residue was purified by silica gel
chromatography using a mixture of ethyl acetate (EtOAc) and hexane
(Hxn) as eluent (EtOAc/Hxn=1:4) to provide 0.470 g, (60% yield) of
the title compound (22c) as a colorless oil. R.sub.f=0.50
(EtOAc/Hxn=1:4). .sup.1H NMR (CDCl.sub.3, 400 MHz): .delta.=0.000
(s, 6H), 0.81 (s, 9H), 1.26 (t, J=7.2 Hz, 3H), 4.22 (q, J=7.2 Hz,
2H), 4.62 (s, 2H) ppm. MS (ESI) m/z 247.07 (M+H).sup.+.
Step D: Ethyl 2,2-diethoxy-3-(1,1,2,2-tetramethyl-1-silapropoxy)
propanoate (22d)
[0461] To a stirred solution of ethyl
2-oxo-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate (22c), 0.362
g (1.469 mmol) in 20 mL of triethylorthoformate at ca. 0.degree. C.
(ice bath) was added a catalytic amount (ca. 0.5 mL) of
concentrated sulfuric acid (H.sub.2SO.sub.4). The reaction mixture
was stirred at 0.degree. C.-10.degree. C. for three to four hours.
The reaction mixture was then diluted with dichloromethane (DCM)
and washed with water and brine. The organic extract was dried over
anhydrous magnesium sulfate (MgSO.sub.4), filtered, and the
solvents removed under reduced pressure using a rotary evaporator
to provide 0.2 g (43% yield) of the title compound (22d) as a
colorless oil that was of sufficient purity to be used in the next
step without further purification. R.sub.f=0.20 (EtOAc/Hxn=1:4).
.sup.1H NMR (CDCl.sub.3, 400 MHz): .delta.=0.000 (s, 6H), 0.83 (s,
9H), 1.19 (t, J=6.8 Hz, 3H), 1.27 (t, J=7.2 Hz, 6H), 3.39-3.48 (m,
2H), 3.54-3.64 (m, 2H), 3.81 (s, 2H), 4.21 (q, J=7.2 Hz, 2H)
ppm.
Step E: Ethyl 2,2-diethoxy-3-hydroxy propanoate (22e)
[0462] Adapting procedures or variations thereof according to Bhat
et al., Bioorg. & Med. Chem. Lett. 1998, 8, 3181-3186, a 100 mL
round-bottomed flask equipped with a magnetic stirring bar was
charged with 200 mg (0.63 mmol) of ethyl
2,2-diethoxy-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate (22d).
Fifteen (15) mL of a mixture of ethanol (EtOH) and concentrated
hydrochloric acid (99:1 v/v) were added and the reaction mixture
was stirred overnight at room temperature. The solvents were
evaporated under reduced pressure using a rotary evaporator and a
high vacuum pump to provide 120 mg (93% yield) of the title
compound (22e) as a colorless oil that was of sufficient purity to
be used directly in the next step without further purification and
characterization.
Step F: Ethyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-diethoxypropanoate
(22)
[0463] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs of Description 3
(Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1) (ca. 350 mg,
1.75 mmol) dissolved in 10 mL of dichloromethane was reacted with
ethyl 2,2-diethoxy-3-hydroxy propanoate (22e) (200 mg, 0.969 mmol)
in the presence of 243 .mu.L of triethylamine (176 mg, 1.74 mmol)
and 211 mg (1.73 mmol) of DMAP. After mass-guided preparative HPLC
purification, 10 mg (3% yield) of the title compound (22) was
obtained as a colorless oil. .sup.1H NMR (400 MHz, MeOH-d.sup.4):
.delta.=1.23 (t, J=7.2 Hz, 6H), 1.33 (t, J=7.6 Hz, 3H), 1.94-2.01
(m, 5H), 3.25-3.31 (m, 4H), 3.49-3.57 (m, 2H), 3.60-3.69 (m, 2H),
4.28 (q, J=7.2 Hz, 2H), 4.42 (s, 2H) ppm. MS (ESI) m/z 370.15
(M+H).sup.+; 392.14 (M+Na).sup.+.
Example 23
Benzyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-diethoxypropanoate
(23)
Step A: rac-Benzyl glycerate (23a)
[0464] Adapting a procedure according to Choi et al., Bioorg. Med.
Chem. 1996, 4, 2105-2114, a 1,000 mL round-bottomed flask equipped
with a magnetic stirring bar was charged with 16.0 g (101.7 mmol)
of potassium permanganate (KMnO.sub.4). The oxidant was dissolved
in 150 mL of water and 300 mL of acetone and the reaction mixture
was cooled to ca. -78.degree. C. using a dry ice/acetone bath. 15.0
g (92.5 mmol) of benzyl acrylate was slowly added while stirring at
-78.degree. C., and the reaction mixture then slowly warmed to
0.degree. C. The inorganic salts were removed by filtration and the
filter residue washed with 150 mL of acetone. The combined
filtrates were concentrated under reduced pressure at temperatures
below 40.degree. C. using a rotary evaporator. The product was
extracted with ethyl acetate (3.times.200 mL) and the combined
extracts were dried over anhydrous sodium sulfate
(Na.sub.2SO.sub.4). After filtration, the solvent was removed under
reduced pressure using a rotary evaporator. The crude material was
purified by silica gel chromatography using a mixture of ethyl
acetate (EtOAc) and hexane (Hxn) as eluent (EtOAc/Hxn=1:4) to
provide 6.0 g (33% yield) of the title compound (23a) as a clear,
colorless oil. R.sub.f=0.50 (CHCl.sub.3/Acetone=9:1). .sup.1H NMR
(CDCl.sub.3, 400 MHz): .delta.=2.61-2.83 (br. m, 2H), 3.87 (dd,
J=12.0, 3.6 Hz, 1H), 3.92 (dd, J=11.6, 3.2 Hz, 1H), 3.12 (br. t,
J=3.6 Hz, 1H), 5.24 (d, J=12.4 Hz, 1H), 5.27 (d, J=12.4 Hz, 1H),
7.32-7.40 (m, 5H) ppm. MS (ESI) m/z 197.06 (M+H).sup.+. The
analytical data was consistent with that given in Shin, et al., J.
Org. Chem., 2000, 65, 7667-7675.
Step B: rac-Benzyl
2-hydroxy-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate (23b)
[0465] Adapting procedures or variations thereof according to Shin
et al., J Org. Chem. 2000, 65, 7667-7675 and Parkkari et al.,
Bioorganic Med. Chem. Lett. 2004, 14, 3231-3234, a 250 mL
round-bottomed flask equipped with a magnetic stirring bar was
charged with 2.0 g (10.2 mmol) of rac-benzyl glycerate (23a) and
the material dissolved in 40 mL of anhydrous dichloromethane (DCM).
Imidazole (0.69 g, 10.2 mmol), 10.2 mL of a one molar (1.0 M)
solution of tert-butyl dimethylchlorosilane in DCM, and 0.50 g,
(4.1 mmol) of 4-(N,N-dimethylamino)pyridine (DMAP) were added. The
reaction mixture was stirred overnight at room temperature. The
reaction mixture was then diluted with 100 mL of DCM and washed
twice with water and brine. The combined organic extracts were
dried over anhydrous magnesium sulfate (MgSO.sub.4). After
filtration, the solvent was removed under reduced pressure and
purified by silica gel chromatography using a mixture of ethyl
acetate (EtOAc) and hexane (Hxn) as eluent (EtOAc/Hxn=95:5) to
provide 2.0 g (75% yield) of the title compound (23b) as a clear
oil. R.sub.f=0.60 (EtOAc/Hxn=1:4). .sup.1H NMR (400 MHz,
CDCl.sub.3): .delta.=0.03 (s, 3H), 0.06 (s, 3H), 0.87 (s, 9H), 3.06
(d, J=7.6 Hz, 1H), 3.87 (dd, J=10.4, 3.2 Hz, 1H), 3.97 (dd, J=10.4,
3.2 Hz, 1H), 4.26 (br. dt, J=8.4, 3.2 Hz, 1H), 5.22 (s, 2H),
7.33-7.38 (m, 5H), ppm. MS (ESI) m/z=311.19 (M+H).sup.+. The
analytical data was consistent with that given in Shin, et al., J.
Org. Chem., 2000, 65, 7667-7675; and Carreiro, et al., ES 2006959
(1989).
Step C: Benzyl
2-oxo-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate (23c)
[0466] Adapting procedures or variations thereof according to Dess
et al., J. Am. Chem. Soc. 1991, 113, 7277-7287, to a stirred
solution of benzyl 2-oxo-3-(1,1,2,2-tetramethyl-1-silapropoxy)
propanoate (23b), 1.8 g (5.8 mmol) of
1,1,1-tris(acetyloxy)-1,1-dihydro-1,2-benziodoxol-3-(1H)-one
(Dess-Martin periodinane) in 10 mL of anhydrous dichloromethane was
added at ca. 0.degree. C. (ice bath) 3.0 g (7.0 mmol). The reaction
mixture was stirred for six hours at room temperature. The solvent
was then removed under reduced pressure using a rotary evaporator.
The residue was diluted with 100 mL of diethyl ether and washed
twice with a saturated sodium bicarbonate (NaHCO.sub.3) solution
and subsequently with a 10 wt-% aqueous solution of sodium
thiosulfate (Na.sub.2S.sub.2O.sub.3). The combined organic extracts
were dried over anhydrous magnesium sulfate (MgSO.sub.4). The
solvents were removed under reduced pressure using a rotary
evaporator to provide 1.7 g (95% yield) of the title compound (23c)
as a colorless oil. The material was of sufficient purity to be
used in the next step without further purification or isolation.
R.sub.f=0.50 (EtOAc/Hxn=1:4). .sup.1H NMR (400 MHz, CDCl.sub.3):
.delta.=0.10 (s, 6H), 0.92 (s, 9H), 4.74 (s, 2H), 5.29 (s, 2H),
7.36-7.39 (m, 5H) ppm. MS (ESI) m/z 307.12 (M+H).sup.+.
Step D: Benzyl
2,2-diethoxy-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate
(23d)
[0467] A catalytic amount (ca. 2.1 mL) of concentrated sulfuric
acid (H.sub.2SO.sub.4) was added to a solution of benzyl
2-oxo-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate (23c), 1.7 g,
(5.5 mmol) in ca. 90 mL (80.2 g, 0.54 mol) of triethylorthoformate
while stirring at ca. 0.degree. C. (ice bath). The reaction mixture
was stirred at 0.degree. C.-10.degree. C. for three to four hours.
The reaction mixture was then diluted with dichloromethane (DCM)
and washed with water and brine. The organic extract was dried over
anhydrous magnesium sulfate (MgSO.sub.4), filtered, and the solvent
removed under reduced pressure using a rotary evaporator to provide
2.0 g (95% yield) of the title compound (23d) as a colorless oil
that was of sufficient purity to be used in the next step without
further purification. R.sub.f=0.60 (EtOAc/Hxn=1:4). .sup.1H NMR
(400 MHz, CDCl.sub.3): .delta.=0.003 (s, 6H), 0.85 (s, 9H), 1.23
(t, J=7.2 Hz, 6H), 3.40-3.64 (m, 4H), 3.84 (s, 2H), 5.26 (s, 2H),
7.30-7.40 (m, 5H) ppm. MS (ESI) m/z 383.19 (M+H).sup.+, 405.15
(M+Na).sup.+.
Step E: Benzyl 2,2-diethoxy-3-hydroxy propanoate (23e)
[0468] Adapting a procedure or a variation thereof according to
Bhat et al., Bioorg. Med. Chem. Lett. 1998, 8, 3181-3186, a 100 mL
round-bottomed flask equipped with a magnetic stirring bar was
charged with 2.0 g (5.23 mmol) of benzyl
2,2-diethoxy-3-(1,1,2,2-tetramethyl-1-silapropoxy)propanoate (23d).
Fifteen (15) mL of a mixture of ethanol (EtOH) and concentrated
hydrochloric acid (95:5 v/v) was added and the reaction mixture
stirred overnight at room temperature. The solvents were evaporated
under reduced pressure using a rotary evaporator and a high vacuum
pump to provide 1.4 g (99% yield) of the title compound (23e) as a
colorless oil that was of sufficient purity to be used directly in
the next step without further purification or isolation. MS (ESI)
m/z: 291.1(M+Na).sup.+.
Step F: Benzyl
3-{[3-(acetylamino)propyl]sulfonyloxy}-2,2-diethoxypropanoate
(23)
[0469] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs of Description 3
(Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1) (ca. 225 mg,
1.11 mmol) dissolved in 10 mL of dichloromethane was reacted with
benzyl 2,2-diethoxy-3-hydroxy propanoate (23e) (250 mg, 0.932 mmol)
in the presence of 155 .mu.L of triethylamine (113 mg, 1.12 mmol)
and 137 mg (1.12 mmol) of DMAP. After mass-guided preparative HPLC
purification, 32 mg (8% yield) of the title compound (23) was
obtained as a colorless oil. .sup.1H NMR (400 MHz, DMSO-d.sup.6):
.delta.=1.23 (t, J=7.2 Hz, 6H), 1.70-1.78 (m, 2H), 1.80 (s, 3H),
3.07-3.13 (m, 2H), 3.31-3.37 (m, 2H), 3.37-3.46 (m, 2H), 3.50-3.59
(m, 2H), 4.38 (s, 2H), 5.21 (s, 2H), 7.31-7.40 (m, 5H), 7.89 (br.
t, J=5.2 Hz, 1H) ppm. MS (ESI) m/z 432.1 (M+H).sup.+; 454.1
(M+Na).sup.+.
Example 24
Methyl 4-{[3-(acetylamino)propyl]sulfonyloxy}-3,3-dimethylbutanoate
(24)
Step A: 2,2-Dimethyl-pent-4-en-1-ol (24a)
[0470] Adapting a procedure or a variation thereof according to
Chen et al., J. Am. Chem. Soc. 2003, 125, 6697-6704, an oven dried
500 mL round-bottomed flask equipped with a magnetic stirring bar
and a pressure equalized addition funnel was charged under a
nitrogen atmosphere with 5.00 g (39.0 mmol) of commercially
available 2,2-dimethyl-4-pentenoic acid. The acid was dissolved in
100 mL of anhydrous tetrahydrofuran (THF) and cooled to ca.
0.degree. C. (ice bath). Forty (40) mL of a one molar (1.0 M)
solution of lithium aluminum hydride (LAH) in THF was slowly added
at this temperature and the reaction mixture then stirred overnight
with slow warming to room temperature followed by subsequent
cooling to ca. 0.degree. C. (ice bath). Subsequent and careful
addition of 2.6 mL of water, 5.2 mL of a 10 wt-% aqueous solution
of sodium hydroxide (NaOH), and 2.6 mL of water resulted in a
colorless precipitate that was filtered off. The filter residue was
washed with ethyl acetate (EtOAc) and the combined filtrates were
dried over anhydrous magnesium sulfate (MgSO.sub.4) and filtered.
Solvents were evaporated under reduced pressure using a rotary
evaporator to provide 4.05 g (91% yield) of the title compound
(24a) as a colorless oil. R.sub.f=0.30 (EtOAc/Hxn=1:9). .sup.1H NMR
(400 MHz, CHCl.sub.3): .delta.=0.91 (s, 6H), 2.04 (d, J=8.0 Hz,
2H), 3.34 (s, 2H), 5.01-5.10 (m, 2H), 5.79-5.91 (m, 1H) ppm. MS
(ESI) m/z 114.86 (M+H).sup.+. The analytical data for the compound
was consistent with the structure and the data reported in the
literature.
[0471] Alternatively, the title compound (24a) was prepared in
comparable yield starting from the corresponding alkyl esters of
acid employing comparable synthetic methods, or from commercially
available 2,2-dimethyl-4-pentenal through reduction of the aldehyde
functionality with sodium borohydride (NaBH.sub.4) in ethanol
(EtOH) at room temperature.
Step B: 2,2-Dimethylpent-4-enyl [3-(acetylamino)propyl]sulfonate
(24b)
[0472] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs of Description 3
(Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1) (2.6 g, 13
mmol) dissolved in 50 mL of dichloromethane was reacted with
2,2-dimethyl-pent-4-en-1-ol (24a) (1.0 g, 8.8 mmol) in the presence
of 1.9 mL of triethylamine (1.4 g, 14.0 mmol) and 170 mg (1.4 mmol)
of DMAP. After aqueous work-up, the residue was purified by silica
gel chromatography using ethyl acetate (EtOAc) as eluent to provide
1.4 g (57% yield) of the title compound (24b) as a colorless oil.
R.sub.f=0.33 (EtOAc). .sup.1H NMR (400 MHz, CDCl.sub.3):
.delta.=0.98 (s, 6H), 2.01 (s, 3H), 2.06-2.12 (m, 4H), 3.15-3.19
(m, 2H), 3.43 (dd, J=12.8, 6.8Hz, 2H), 3.90 (s, 2H), 5.04-5.12 (m,
2H), 5.72-5.81 (m, 2H), 5.87 (br. m, 1H) ppm. MS (ESI) m/z 278.12
(M+H).sup.+.
Step C: 2,2-Dimethyl-4-oxobutyl [3-(acetylamino)propyl]sulfonate
(24c)
[0473] Adapting a procedure or a variation thereof according to
Pappo et al., J. Org. Chem. 1956, 21, 478-479, a stirred solution
of 2,2-dimethylpent-4-enyl [3-(acetylamino)propyl]sulfonate (24b)
(0.1 g, 0.36 mmol) in 3 mL of a mixture of water and
tetrahydrofuran (THF) (1:1 v/v) was reacted with 0.36 mL of a 2.5
wt-% solution of osmiumtetroxide (OsO.sub.4) in tert-butanol and in
the presence of 0.15 g (0.72 mmol) of sodium metaperiodate
(NaIO.sub.4). The reaction was monitored by analytical LC/MS. After
the starting material was completely consumed, the reaction was
quenched by adding a 10 wt-% aqueous sodium hydrogensulfite
solution (NaHSO.sub.3). The reaction mixture was then extracted
twice with ethyl acetate. The combined organic extracts were
subsequently washed with a 10 wt-% aqueous NaHSO.sub.3 solution and
brine, dried over magnesium sulfate (MgSO.sub.4), filtered, and the
solvents removed under reduced pressure using a rotary evaporator
to provide ca. 0.1 g (95% yield) of the title compound (24c) as a
colorless oil. The resulting crude material was of sufficient
purity for use in the next step without further purification.
R.sub.f=0.15 (EtOAc). .sup.1H NMR (400 MHz, CDCl.sub.3):
.delta.=1.14 (s, 6H), 2.00 (s, 3H), 2.02-2.09 (m, 2H), 2.45 (d,
J=2.0 Hz, 2H), 3.15-3.19 (m, 2H), 3.37-3.42 (m, 2H), 4.03 (s, 2H),
5.98-6.05 (br. m, 1H), 9.79 (t, J=2.0 Hz, 1H) ppm. MS (ESI) m/z
280.08 (M+H).sup.+.
Step D: Methyl
4-{[3-(acetylamino)propyl]sulfonyloxy}-3,3-dimethylbutanoate
(24)
[0474] Adapting a procedure or a variation thereof according to
McDonald et al., J. Org. Chem. 1989, 54, 1213-1215, to a stirred
solution of 2,2-dimethyl-5-oxobutyl
[3-(acetylamino)propyl]sulfonate (24c) (0.2 g, 0.68 mmol) and
methanol (0.23 mL, 0.24 g, 2.2 mmol) in 10 mL of acetonitrile were
added 0.31 g (1.4 mmol) N-iodosuccinimide (NIS) and potassium
carbonate (K.sub.2CO.sub.3) (0.28 g, 2.0 mmol). The reaction
mixture was stirred overnight at room temperature. The reaction
mixture was then diluted with water and extracted twice with ethyl
acetate. The combined organic extracts were washed with a 10 wt-%
aqueous sodium thiosulfate solution (Na.sub.2S.sub.2O.sub.3) and
brine, dried over magnesium sulfate (MgSO.sub.4), filtered, and the
solvents removed under reduced pressure using a rotary evaporator.
The residue was purified by silica gel chromatography using a
mixture of ethyl acetate (EtOAc) and methanol (MeOH) as eluent
(EtOAc/MeOH=4:1) to provide 13 mg (12% yield) of the title compound
(24) as a colorless oil. .sup.1H NMR (400 MHz, CHCl.sub.3):
.delta.=1.07 (s, 6H), 2.00 (s, 3H), 2.03-2.10 (m, 2H), 2.34 (s,
2H), 3.17-3.21 (m, 2H), 3.37-3.43 (m, 2H), 3.67 (s, 3H), 4.06 (s,
2H), 6.10-6.20 (br. m, 1H) ppm. MS (ESI) m/z 310.15
(M+H).sup.+.
Example 25
Phenylmethyl
4-{[3-(acetylamino)propyl]sulfonyloxy}-3,3-dimethylbutanoate
(25)
[0475] Adapting a procedure or a variation thereof according to
McDonald et al., J. Org. Chem. 1989, 54, 1213-1215,
N-iodosuccinimide (NIS) (0.63 g, 2.8 mmol) and potassium carbonate
K.sub.2CO.sub.3 (0.39 g, 2.8 mmol) were added to a solution of
2,2-dimethyl-4-oxobutyl [3-(acetylamino)propyl]sulfonate (24c)
(0.26 g, 0.93 mmol) and benzyl alcohol (0.29 mL, 0.30 g, 2.8 mmol)
in 5 mL acetonitrile while stirring. The mixture was stirred
overnight at room temperature. The reaction mixture was then
diluted with water and extracted twice with ethyl acetate. The
combined organic extracts were washed with a 10 wt-% aqueous sodium
thiosulfate solution (Na.sub.2S.sub.2O.sub.3) and brine, dried over
magnesium sulfate (MgSO.sub.4), filtered, and the solvents removed
under reduced pressure using a rotary evaporator. The residue was
purified by mass-guided preparative HPLC to provide 17 mg (5%
yield) of the title compound (25) as a colorless oil. .sup.1H NMR
(400 MHz, CHCl.sub.3): .delta.=1.08 (s, 6H), 2.00 (s, 3H),
2.02-2.09 (m, 2H), 2.40 (s, 2H), 3.12-3.17 (m, 2H), 3.38 (q, J=6.4
Hz, 2H), 4.07 (s, 2H), 5.12 (s, 2H), 5.80-5.88 (br. m, 1H),
7.33-7.40 (m, 5H) ppm. MS (ESI) m/z 386.02 (M+H).sup.+; m/z 408.03
(M+Na).sup.+.
Alternative Synthesis of Phenylmethyl
4-{[3-(acetylamino)propyl]sulfonyloxy}-3,3-dimethylbutanoate
(25)
Step A: 2,2-Dimethyl-4-oxobutyl [3-(acetylamino)propyl]sulfonate
(25a)
[0476] A 100 mL round bottomed flask equipped with a magnetic
stirring bar and a perforated polyethylene stopper with a 14
gauge-needle connected via silicon tubing to a Welsbach Standard
T-Series ozone generator was charged with 550 mg (1.99 mmol) of
2,2-dimethylpent-4-enyl [3-(acetylamino)propyl]sulfonate (24b) and
dissolved in 15 mL of anhydrous dichloromethane. The solution was
cooled to ca. -78.degree. C. (dry ice/acetone) and an ozone/oxygen
gas mixture was purged through the solution until an intensely blue
color indicated an excess of dissolved ozone in the reaction
mixture. Excess ozone was removed by successive purges with oxygen
and nitrogen gas. Seven-hundred thirty-four (734) .mu.L (621 mg,
10.0 mmol) of dimethyl sulfide was added and the reaction mixture
stirred overnight with gradual warming to room temperature. The
solvents were then removed under reduced pressure using a rotary
evaporator. The residue was purified by silica gel column
chromatography using mixtures of ethyl acetate (EtOAc) and methanol
(MeOH) as eluent (100% EtOAc.fwdarw.EtOAc/2.5 vol-%
MeOH.fwdarw.EtOAc/5 vol-% MeOH.fwdarw.EtOAc/10 vol-% MeOH) to
provide 385 mg (69% yield) of the title compound (25a) as a
colorless oil. R.sub.f=0.40 (EtOAc/MeOH=95:5). The analytical data
for the compound was consitent with the proposed structure and data
obtained from material prepared using the
OsO.sub.4/NaIO.sub.4-route.
Step B: 4-{[3-(Acetylamino)propyl]sulfonyloxy}-3,3-dimethylbutanoic
Acid (25b)
[0477] Adapting a procedure or a variation thereof according to
Fillmore et al., Encyclopedia of Reagents for Organic Synthesis,
John Wiley & Sons, Ltd., 2001, Jones reagent (chromic acid) was
freshly prepared prior to use from 2.00 g (20.0 mmol) of chromium
trioxide and 1.333 mL (2.45 g, 25.0 mmol) of concentrated sulfuric
acid (H.sub.2SO.sub.4). The chemicals were carefully mixed at
0.degree. C. and the resulting mixture was diluted at the same
temperature with water to a total volume of 10 mL to provide an
aqueous chromic acid preparation of approximately 2.0 M. The
reagent was used without further purification or isolation in the
next step.
[0478] Adapting a procedure or variation thereof according to
Petrini, et al., Tetrahedron, 1986, 42, 151-154, a 4 mL vial
equipped with a magnetic stirring bar and screw cap was charged
with 55 mg (0.197 mmol) of 2,2-dimethyl-4-oxobutyl
[3-(acetylamino)propyl]sulfonate (26a) and 1.6 mL of acetone. To
the cooled reaction mixture (ca. 0.degree. C., ice bath), 111 .mu.L
(ca. 0.222 mmol) of the freshly prepared Jones-reagent was added
and the reaction mixture stirred for two hours with gradual warming
to room temperature. Excess Jones-reagent was consumed by adding
100 .mu.L of isopropanol (i-PrOH) and stirring for 30 minutes at
room temperature. The reaction mixture was then diluted with water
(pH<1) and extracted with ethyl acetate (EtOAc). The combined
organic extracts were washed with brine, dried over magnesium
sulfate (MgSO.sub.4), filtered, and evaporated under reduced
pressure using a rotary evaporator to provide ca. 50 mg (86% yield)
of the title compound (25b) as a colorless oil that was of
sufficient purity to be used in the next step without further
purification or isolation. .sup.1H NMR (400 MHz, CDCl.sub.3):
.delta.=1.13 (s, 6H), 2.00-2.12 (m, 5H), 2.38 (s, 2H), 3.14-3.22
(m, 2H), 3.36-3.44 (m, 2H), 4.12 (s, 2H), 6.14-6.22 (m, 1H) ppm. MS
(ESI) m/z 296.01 (M+H).sup.+; m/z 317.95 (M+Na).sup.+; m/z 293.98
(M-H).sup.-.
[0479] Alternatively, the title compound (25b) was prepared under
mild conditions starting from the unsaturated precursor compound
2,2-dimethylpent-4-enyl [3-(acetylamino)propyl]sulfonate (24c)
according to a method described by Henry et al., J. Org. Chem.
1993, 58, 4745. In one synthesis, 100 mg (0.36 mmol) of
2,2-dimethylpent-4-enyl [3-(acetylamino)propyl]sulfonate (24c)
dissolved in 3 mL of acetone was reacted with 360 .mu.L (0.04 mmol,
ca. 10 mol-%) of a 2.5 wt-% solution of osmiumtetroxide (OsO.sub.4)
in tert-butanol (t-BuOH) and 650 .mu.L (ca. 1.30 mmol) of freshly
prepared Jones-reagent (ca. 2 M). The reaction mixture was stirred
overnight with gradual warming to room temperature. Excess
Jones-reagent was then consumed by adding 100 .mu.L of isopropanol
(i-PrOH) and stirring for 30 minutes at room temperature followed
by the addition of 250 .mu.L of an aqueous 10 wt-% solution of
sodium hydrogensulfite (NaHSO.sub.3). The reaction mixture was
diluted with water (pH<1) and extracted with dichloromethane
(DCM). The combined organic extracts were washed with an aqueous
one molar solution of hydrogen chloride (HCl) and brine, dried over
magnesium sulfate (MgSO.sub.4), filtered, and evaporated under
reduced pressure using a rotary evaporator to provide 100 mg (95%
yield) of the title compound (25b) as a colorless oil that was of
sufficient purity to be used in the next step without further
purification or isolation. The analytical data for the compound was
consistent with the proposed structure and the data obtained from
material prepared using the sequential route.
Step C:
3-(Chlorocarbonyl)-2,2-dimethylpropyl[3-(acetylamino)propyl]sulfon-
ate (25c)
[0480] An oven dried 100 mL round bottomed flask equipped with a
magnetic stirring bar and a rubber septum was charged with ca. 50
mg (0.17 mmol) of
4-{[3-(acetylamino)propyl]sulfonyloxy}-3,3-dimethylbutanoic acid
(25b). The material was dissolved in 5 mL of anhydrous
dichloromethane (DCM) and two small drops of anhydrous
N,N-dimethylformamide (DMF). The solution was cooled to ca.
0.degree. C. (ice bath) and 150 .mu.L (0.3 mmol) of a two molar
solution (2 M) of oxalyl chloride in DCM was added. The reaction
mixture was stirred with gradual warming to room temperature for
three hours and the solvents then removed under reduced pressure on
a rotary evaporator to provide the title compound (25c) as a clear,
oily semisolid that was used directly in the next step without
further purification or characterization.
Step D: Phenylmethyl
4-{[3-(acetylamino)propyl]sulfonyl-oxy}-3,3-dimethylbutanoate
(25)
[0481] An oven dried 100 mL round bottomed flask equipped with a
magnetic stirring bar and a rubber septum was charged with freshly
prepared acid chloride 3-(chlorocarbonyl)-2,2-dimethylpropyl
[3-(acetylamino)propyl]sulfonate (25c). The material was dissolved
in 3 mL of anhydrous dichloromethane (DCM). One-hundred three (103)
.mu.L (108 mg, 1.0 mmol) of anhydrous benzyl alcohol and 61 mg (0.5
mmol) of 4-(N,N-dimethylamino)-pyridine and 40 .mu.L (40 mg, 0.5
mmol) of anhydrous pyridine were added and the reaction mixture
stirred overnight at room temperature. The solvents were then
removed under reduced pressure using a rotary evaporator and the
residue diluted with ethyl acetate (EtOAc). The solution was washed
with a one molar aqueous solution of hydrogen chloride (HCl), a
saturated aqueous solution of sodium hydrogencarbonate
(NaHCO.sub.3) and brine, dried over anhydrous magnesium sulfate
(MgSO.sub.4), filtered, and the solvent removed under reduced
pressure using a rotary evaporator. The residue was purified by
silica gel column chromatography using mixtures of EtOAc and
methanol (MeOH) as eluent (100% EtOAc.fwdarw.EtOAc/MeOH=95:5) to
provide 36 mg (47% yield over three steps) of the title compound
(25) as a colorless oil. The analytical data for the compound was
consistent with the proposed structure and the data obtained from
material prepared using the two step route, e.g., (i)
OsO.sub.4/NaIO.sub.4 and (ii) NIS/ROH).
Example 26
2,2-Dimethyl-5-oxapentyl [3-(acetylamino)propyl]sulfonate (26)
Step A: 2,2-Dimethylhex-5-en-1-ol (26a)
[0482] Adapting procedures or a variations thereof according to
Juaristi et al., J. Org. Chem. 1991, 56, 1623-1630; Ashby et al.,
J. Org. Chem. 1984, 49, 3545-3556; or Beckwith et al., J. Chem.
Soc., Perkin Trans. 2: Phys. Org. Chem. 1979, 1535-1539, an
oven-dried 100 mL round-bottomed flask equipped with a magnetic
stirring bar and a pressure equalized addition funnel was charged
under a nitrogen atmosphere with 1.04 g (7.33 mmol) of commercially
available 2,2-dimethyl-5-hexenoic acid. The acid was dissolved in
20 mL of anhydrous tetrahydrofuran (THF) and cooled to ca.
0.degree. C. (ice bath). Eight (8.0) mL of a one molar solution
(1.0 M) of lithium aluminum hydride (LAH) in THF was slowly added
and the reaction mixture stirred for three hours with slow warming
to room temperature followed by cooling to ca. 0.degree. C. (ice
bath). Careful addition of 0.49 mL of water, 0.98 mL of a 10 wt-%
aqueous solution of sodium hydroxide (NaOH), and 0.49 mL of water
resulted in a colorless precipitate that was filtered off. The
filter residue was washed with ethyl acetate (EtOAc) and the
combined filtrates were dried over anhydrous magnesium sulfate
(MgSO.sub.4), filtered, and the solvents evaporated under reduced
pressure using a rotary evaporator. The residue was purified by
silica gel chromatography using a mixture of ethyl acetate (EtOAc)
and hexane (Hxn) as eluent (EtOAc/Hxn=1:3) to provide 548 mg (58%
yield) of the title compound (26a) as a colorless oil. R.sub.f=0.42
(EtOAc/Hxn=1:4). .sup.1H NMR (400 MHz, CHCl.sub.3): .delta.=0.91
(s, 6H), 1.30-1.40 (m, 2H), 2.00-2.08 (m, 2H), 3.35 (s, 2H),
4.91-5.06 (m, 2H), 5.78-5.90 (m, 1H) ppm. MS (ESI) m/z 129.12
(M+H).sup.+. The analytical data for the compound was consistent
with the proposed structure and the data reported in the
literature.
Step B: 2,2-Dimethylhex-5-enyl [3-(acetylamino)propyl]sulfonate
(26b)
[0483] Following the general procedure for the synthesis of
acamprosate neopentyl sulfonylester prodrugs or intermediates of
Description 3 (Method A), N-[3-(chlorosulfonyl)propyl]acetamide (1)
(1.7 g, 8.6 mmol), dissolved in 50 mL of dichloromethane, was
reacted with 2,2-dimethylhex-5-en-1-ol (26a) (0.55 g, 4.3 mmol) in
the presence of 1.2 mL of triethylamine (0.87 g, 8.6 mmol) and 100
mg (0.8 mmol) of DMAP. After aqueous work-up, the residue was
purified by silica gel chromatography using a mixture of ethyl
acetate (EtOAc) and methanol (MeOH) as eluent (EtOAc/MeOH=4:1) to
provide 500 mg (40% yield) of the title compound (26b) as a
colorless oil. .sup.1H NMR (400 MHz, CHCl.sub.3): .delta.=0.98 (s,
6H), 1.38-1.41 (m, 2H), 2.06 (s, 3H), 2.06-2.12 (m, 4H), 3.15-3.19
(m, 2H), 3.43 (dd, J=12.8, 6.4 Hz, 2H), 3.92 (s, 2H), 4.94-5.05 (m,
2H), 5.75-5.85 (m, 1H) ppm. MS (ESI) m/z 292.02 (M+H).sup.+.
Step C: 2,2-Dimethyl-5-oxopentyl [3-(acetylamino)propyl]sulfonate
(26)
[0484] Adapting a procedure or a variation thereof according to
Pappo et al., J. Org. Chem. 1956, 21, 478-479, a stirred solution
of 2,2-dimethylhex-5-enyl [3-(acetylamino)propyl]sulfonate (26b)
(0.5 g, 1.7 mmol) in 15 mL of a mixture of water and
tetrahydrofuran (THF) (1:1 v/v) was reacted with 2.0 mL of a 2.5
wt-% solution of osmiumtetroxide (OsO.sub.4) in tert-butanol in the
presence of 0.75 g (3.45 mmol) of sodium metaperiodate
(NaIO.sub.4). The reaction was monitored using analytical LC/MS.
After the starting material was completely consumed, the reaction
was quenched by adding a 10 wt-% aqueous sodium hydrogensulfite
solution (NaHSO.sub.3). The reaction mixture was then extracted
twice with ethyl acetate. The combined organic extracts were
subsequently washed with a 10 wt-% aqueous NaHSO.sub.3 solution and
brine, dried over magnesium sulfate (MgSO.sub.4), filtered, and the
solvents removed under reduced pressure using a rotary evaporator.
The residue was purified by silica gel chromatography using a
mixture of ethyl acetate (EtOAc) and methanol (MeOH)
(EtOAc/MeOH=4:1) as eluent to provide 200 mg (45% yield) of the
title compound (26) as a colorless oil. R.sub.f=0.66
(EtOAc/MeOH=4:1). .sup.1H NMR (400 MHz, CHCl.sub.3): .delta.=0.96
(s, 6H), 1.62-1.66 (m, 2H), 2.03 (s, 3H), 2.01-2.08 (m, 2H),
2.43-2.47 (m, 2H), 3.14-3.18 (m, 2H), 3.35-3.40 (m, 2H), 3.88 (s,
2H), 6.24-6.28 (br. m, 1H), 9.75 (t, J=2.0 Hz, 1 H) ppm. MS (ESI)
m/z 293.98 (M+H).sup.+.
Alternative Synthesis of 2,2-Dimethyl-5-oxopentyl
[3-(acetylamino)propyl]sulfonate (26)
[0485] In one qualitative experiment, a 100 mL round bottomed flask
equipped with a magnetic stirring bar and a perforated polyethylene
stopper with a 14 gauge-needle connected via silicon tubing to a
Welsbach Standard T-Series ozone generator was charged with
2,2-dimethylhex-5-enyl [3-(acetylamino)propyl]sulfonate (26b) and
dissolved in anhydrous dichloromethane (DCM). The solution was
cooled to ca. -78.degree. C. (dry ice/acetone) and an ozone/oxygen
gas mixture was purged through the solution until an intensely blue
color indicated an excess of dissolved ozone in the reaction
mixture. Excess ozone was removed by successive purges with oxygen
and nitrogen gas. An excess of dimethyl sulfide was added and the
reaction mixture was stirred overnight with gradual warming to room
temperature. The solvents were then removed under reduced pressure
using a rotary evaporator. The residue was purified by silica gel
column chromatography using mixtures of ethyl acetate (EtOAc) and
methanol (MeOH) as eluent to provide the title compound (26) as a
colorless oil. R.sub.f=0.40 (EtOAc/MeOH=95:5). The analytical data
for the compound are was consistent with the proposed structure and
the data obtained from material prepared using the
OsO.sub.4/NaIO.sub.4-route.
Example 27
Phenylmethyl
5-{[3-(acetylamino)propyl]sulfonyloxy}-4,4-dimethylpentanoate
(27)
[0486] Adapting a procedure or a variation thereof according to
McDonald, et al., J. Org. Chem. 1989, 54, 1213-1215, to a stirred
solution of 2,2-dimethyl-5-oxopentyl
[3-(acetylamino)propyl]sulfonate (26) (0.2 g, 0.68 mmol) and benzyl
alcohol (0.23 mL, 0.24 g, 2.2 mmol) in 10 mL of acetonitrile were
added 0.31 g (1.4 mmol) N-iodosuccinimide (NIS) and potassium
carbonate (K.sub.2CO.sub.3) (0.28 g, 2.0 mmol). The reaction
mixture was stirred overnight at room temperature. The reaction
mixture was diluted with water and extracted twice with ethyl
acetate. The combined organic extracts were washed with a 10 wt-%
aqueous sodium thiosulfate solution (Na.sub.2S.sub.2O.sub.3) and
brine, dried over magnesium sulfate (MgSO.sub.4), filtered, and the
solvents removed under reduced pressure using a rotary evaporator.
The residue was purified by mass-guided preparative HPLC to provide
43 mg (16% yield) of the title compound (27) as a colorless oil.
.sup.1H NMR (400 MHz, CDCl.sub.3): .delta.=0.97 (s, 6H), 1.68-1.72
(m, 2H), 1.99 (s, 3H), 2.03-2.10 (m, 2H), 2.35-2.39 (m, 2H),
3.15-3.18 (m, 2H), 3.40 (dd, J=12.8, 6.4Hz, 2H), 3.90 (s, 2H), 5.12
(s, 2H), 5.98-6.02 (br. m, 1H), 7.32-7.37 (m, 5H) ppm. MS (ESI) m/z
400.06 (M+H).sup.+.
Example 28
5-{[3-(Acetylamino)propyl]sulfonyloxy}-4,4-dimethylpentanoic Acid
(28)
[0487] Caution: Chromium(VI) oxide is a highly toxic cancer suspect
agent. All chromium(VI) reagents must be handled with care. The
mutagenicity of Cr(VI) compounds, i.e. chromic acid
(Jones-Reagent), is well documented. Special care must always be
exercised in adding CrO.sub.3 to organic solvents. This reagent
must be handled in a fume hood.
[0488] Adapting a procedure or a variation thereof according to
Fillmore et al., Encyclopedia of Reagents for Organic Synthesis,
John Wiley & Sons, Ltd., 2001, Jones reagent (chromic acid) was
freshly prepared prior to use from 2.00 g (20.0 mmol) of chromium
trioxide and 1.333 mL (2.45 g, 25.0 mmol) of concentrated sulfuric
acid (H.sub.2SO.sub.4). The chemicals were carefully mixed at
0.degree. C. and the resulting mixture was carefully diluted at the
same temperature with water to total volume of 10 mL to yield an
aqueous chromic acid preparation of approximately 2.0 M. The
reagent was used in the next step without further purification or
isolation.
[0489] Adapting a procedure or variation thereof according to
Petrini et al., Tetrahedron, 1986, 42, 151-154, a 100 mL
round-bottomed flask equipped with a magnetic stirring bar was
charged with 2,2-dimethyl-5-oxopentyl
[3-(acetylamino)propyl]sulfonate (26) (580 mg, 1.98 mmol). The
compound was dissolved in 20 mL of acetone, cooled to ca. 0.degree.
C. (ice bath), and 1.19 mL (2.38 mmol) of Jones-reagent (2.0 M in
water) was added while stirring. The reaction mixture turned from
brown to green in about 30 min. After the starting material was
completely consumed, 1 mL of isopropanol (iPrOH) was added to
destroy excess oxidant. The reaction mixture was diluted with water
and extracted with ethyl acetate. The combined organic extracts
were washed with brine, dried over anhydrous magnesium sulfate
(MgSO.sub.4), filtered, and the solvents removed under reduced
pressure using a rotary evaporator. After purification by
mass-guided preparative HPLC, 153 mg (25% yield) of the title
compound (28) was obtained as a colorless solid. M.p.:
105.3-124.9.degree. C. .sup.1H NMR (400 MHz, DMSO-d.sup.6):
.delta.=0.89 (s, 6H), 1.49-1.54 (m, 2H), 1.76-1.83 (m, 5H),
2.17-2.22 (m, 2H), 3.10-3.16 (m, 2H), 3.31-3.35 (m, 2H,
superimposed with H.sub.2O signal), 3.88 (s, 2H), 7.90 (br. t,
J=5.6 Hz, 1H), 12.06 (br. s, 1H) ppm. MS (ESI) m/z 310.0
(M+H).sup.+, 332.0 (M+Na).sup.+, 308.0 (M-H).sup.-.
Example 29
Bioavailability of Acamprosate Following Administration of
Acamprosate Prodrugs to Rats
[0490] Rats were obtained commercially and were pre-cannulated in
the jugular vein. Animals were conscious at the time of the
experiment. All animals were fasted overnight and until 4 hours
post-dosing of a prodrug of Formula (I).
[0491] Rat blood samples (0.3 mL/sample) were collected from all
animals prior to dosing and at different time-points up to 24 h
post-dose into tubes containing EDTA. Two aliquots (100 .mu.L each)
were quenched with 300 .mu.L methanol and stored at -20.degree. C.
prior to analysis.
[0492] To prepare analysis standards, 90 .mu.L of rat blood was
quenched with 300 .mu.L methanol followed by 10 .mu.L of spiking
standard and/or 20 .mu.L of internal standard. The sample tubes
were vortexed for at least 2 min and then centrifuged at 3400 rpm
for 20 min. The supernatant was then transferred to an injection
vial or plate for analysis by LC-MS-MS.
[0493] To prepare samples for analysis, 20 .mu.L of internal
standard was added to each quenched sample tube. The sample tubes
were vortexed for at least 2 min and then centrifuged at 3400 rpm
for 20 min. The supernatant was then transferred to an injection
vial or plate for analysis by LC-MS-MS.
[0494] LC-MS-MS analysis was performed using an API 4000 equipped
with Agilent 1100 HPLC and a Leap Technologies autosampler. The
following HPLC column conditions were used: HPLC column:
Thermal-Hypersil-Keystone C18, 4.6.times.100 mm, 5 .mu.m; mobile
phase A: 0.1% formic acid in water; mobile phase B: 0.1% formic
acid in acetonitrile; flow rate: 1.2 mL/min; gradient: 99%A/1%B at
0.0 min; 99%A/1%B at 0.5 min; 5%A/95%B at 1.8 min; 5%A/95%B at 3.5
min; 99%A/1%B at 3.6 min; and 99%A/1%B at 9.0 min. Acamprosate was
monitored in negative ion mode. The LOQ was 0.004 .mu.g/mL. The
standard curve range was 0.004 to 10 .mu.g/mL. Prodrug was
monitored in positive ion mode. The LOQ and standard curve range
was the same as for acamprosate.
[0495] Non-compartmental analysis was performed using WinNonlin
software (v.3.1 Professional Version, Pharsight Corporation,
Mountain View, Calif.) on individual animal profiles. Summary
statistics on major parameter estimates was performed for C.sub.max
(peak observed concentration following dosing), T.sub.max (time to
maximum concentration is the time at which the peak concentration
was observed), AUC.sub.(0-t) (area under the plasma
concentration-time curve from time zero to last collection time,
estimated using the log-linear trapezoidal method),
AUC.sub.(0-.infin.), (area under the plasma concentration time
curve from time zero to infinity, estimated using the log-linear
trapezoidal method to the last collection time with extrapolation
to infinity), and t.sub.1/2,z (terminal half-life).
[0496] Acamprosate or acamprosate prodrug was administered by oral
gavage to groups of four to six adult male Sprague-Dawley rats
(about 250 g). Animals were conscious at the time of the
experiment. Acamprosate or acamprosate prodrug was orally or
colonically administered in 3.4% Phosal at a dose of 70
mg-equivalents acamprosate per kg body weight.
[0497] The percent relative bioavailability (F%) of acamprosate was
determined by comparing the area under the acamprosate
concentration vs time curve (AUC) following oral or colonic
administration of an acamprosate prodrug or acamprosate with the
AUC of the acamprosate concentration vs time curve following
intravenous administration of acamprosate on a dose normalized
basis. Compounds (9) and (11) exhibited an acamprosate oral
bioavailability at least about 5 times greater than the acamprosate
oral bioavailability of an equivalent dose of acamprosate itself.
Compound (9) exhibited an acamprosate colonic bioavailability at
least about 5 times greater than the acamprosate colonic
bioavailability of an equivalent dose of acamprosate itself.
Description 4
Use of Clinical Trials to Assess the Efficacy of Acamprosate
Prodrugs for Maintaining Abstinence from Alcohol
[0498] The efficacy of an acamprosate prodrug for treating
alcoholism can be assessed using a randomized, double-blind,
double-dummy, placebo-controlled trial. Patients aged 18 to 65
years meeting DSM IV criteria for alcohol dependence and having a
history of alcohol dependence for at least 12 months are selected
for the study. Patients are required to have undergone
detoxification and have had five or more days of abstinence from
alcohol before commencing treatment. Patients having a body weight
of less than 60 kg receive an equivalent of 1332 mg/day (two 333 mg
tablets in the morning and one at midday and in the evening) or
placebo, and patients having a bodyweight of greater than 50 kg
receive an acamprosate equivalent of 1998 mg/day (two 333 mg
tablets in the morning, midday and evening) or placebo. Other
acamprosate equivalent doses may be appropriate depending upon the
pharmacokinetics of a particular acamprosate prodrug.
[0499] Primary and secondary outcome measures include commonly
accepted subjective measures (based mainly on self-reported data)
of continuous abstinence rate (CAR, i.e., the percentage of
patients completely abstinent throughout the entire treatment
and/or follow-up period), cumulative abstinence duration (CAD), the
proportion of the total time that CAD represented (CADP, i.e. CAD
as a proportion of the total treatment duration) and/or time to
first drink (TFD). Surrogate biologcial markers of relapse such as
.gamma.-glutamyl transferase, carbohydrate-deficient transferrin,
AST and ALT levels, and mean corpuscular volume can also be
determined. Efficacy of acamprosate prodrugs in the maintenance of
abstinence in patients with alcohol dependence is reflected in an
increased CAR, CADP, and TFD compared to patients receiving
placebo.
Description 5
Use of Animal Models to Assess the Efficacy of Acamprosate Prodrugs
for Treating Alcohol Withdrawal
[0500] Withdrawal Seizure-Prone (WSP) and Withdrawal
Seizure-Resistant (WSR) mice are used to assess the efficacy of
acamprosate prodrugs for treating alcohol withdrawal. Mice are made
dependent on ethanol via 72 h of chronic ethanol vapor inhalation.
On day 1, mice are weighted, injected with a loading dose of
ethanol and pyrazole HCl (Pyr), an alcohol dehydrogenase inhibitor,
and placed into ethanol vapor chambers. Controls are placed into
air chambers and receive Pyr only. At 24 and 48 h, Pyr boosters are
administered to both the experimental and control groups. Blood
ethanol concentrations (BECs) for ethanol groups are measured and
the ethanol vapor concentrations adjusted to equate ethanol
exposure between lines. Mean BECs are maintained between
approximately 1.0-2.0 mg/mL, depending upon the effects of the test
compound being studied. After 72 h, all mice are removed from the
chambers to initiate withdrawal, and ethanol treated mice have
blood samples drawn for BEC determinations.
[0501] Following removal from the ethanol or air chambers, mice are
scored hourly for handling-induced convulsion (HIC). Scoring is
initiated 1 h after removal from ethanol and hourly over the next
12-15 h and again at 24 h. If animals do not return to baseline HIC
levels by 25 h, an additional score is obtained at 48 h. The scale
such as the following is used (0--no convulsion after a gently
180.degree. spin; 1--only facial grimace after gentle 180.degree.
spin; 2--tonic convulsion elicited by gently 180.degree. spin;
3--tonic-clonic convulsion after 180.degree. spin; 4--tonic
convulsion when lifted by tail, no spin; 5--tonic-clonic convulsion
when lifted by tail, no spin; 6--severe tonic-clonic convulsion
when lifted by tail, no spin; and 7--severe tonic-clonic convulsion
elicited before lifting by the tail). The area under the curve is
calculated and used to quantitaively evaluate withdrawal severity.
An additional index of withdrawal severity is the peak HIC score,
calculated by identifying the highest HIC for each individual mouse
and averaging this score with the two adjacent scores. Data are
analyzed by appropriate statistical methods.
Description 6
Animal Model for Assessing Therapeutic Efficacy of Acamprosate
Prodrugs for Treating Tinnitus
Unilateral Noise Trauma
[0502] The efficacy of acamprosate prodrugs of Formula (I) for
treating tinnitus can be assessed using animal models of tinnitus
in which unilateral noise trauma is used to induce tinnitus (Bauer
and Brozoski, J Assoc Res Otolarynology 2001, 2(1), 54-64; and
Guitton et al., US 2006/0063802). Long-Evans rats are first
behaviorally acclimated to lever-press for food pellets and then
conditioned to respond in a distinctive and standard way to
auditory test stimuli. After conditioning, the animals are
separated into groups and exposed to unilateral noise trauma for 0,
1, or 2 hours. Animals are anesthetized, placed in a stereotaxic
head frame, and unilaterally exposed once to narrowband noise with
a peak intensity of 105 dB centered at 16 kHz for 0, 1, or 2 hours
before or after behavioral training and testing. The animals are
then administered an acamprosate prodrug and suppression of the
conditioned response determined and compared to a control group not
exposed to noise trauma.
Sodium Salicylate-Induced Sound Experience
[0503] An animal model developed for short-term, acute induced
phantom auditory sensations in rats can be used to evaluate
acamprosate prodrugs for treating tinnitus. Salicylate-induced
animal models of tinnitus are known.
[0504] Female albino rats (Wistar, aged 8-20 weeks) are trained and
tested on five consecutive days per week. Training and testing
takes place in a commercial conditioning chamber (rat shuttle box,
TSE) adapted for the study. Electrical stimuli (0.1-0.5 mA, 100 V,
0.5 s) can be supplied via a shockable floor ground. A resting
platform with a mechanical sensor was mounted on one side of the
cage, covering the shockable floor and serving as a resting
location for the animal. The cage is separated by a wall into two
short hallways. At both ends of the hallways, within a recess,
small amounts of fluid can be given to an animal, gravity-advanced
and controlled by flow resistance- and vibration-muted magnetic
shutter valves. A typical open time is 0.5 s, resulting in a reward
drop of ca. 20 .mu.L, supplied to an animal via a curved metal
drinking cannula. Reward drops not taken up by the animal are
drained off into a reservoir unreachable by the rat. Photo sensors
registered the visits of an animal at the feeder recesses. All
sensors are monitored on a computer screen and a top-mounted USB
camera provided pictures of the entire floor dimensions of the cage
interior.
[0505] Auditory stimuli are generated and presented over three
broadened speakers mounted vertically in the cage. A continuous
white noise can be plated on the central loudspeaker switched off
and on with a 100 ms ramp. In parallel to the white noise sound, a
pure tone (cue tone, 8 kHz, 70 dB SPL, 200 ms length, 25 ms ramp,
repeated five times with 300 ms pause) could be presented over
loudspeakers mounted directly over the left and right feeder
recesses.
[0506] Animals are trained on auditory stimuli for 30-60 min/day
for 5 days/week. Training session length is adapted to the animal's
activity. Always 15-18 h prior to behavioral testing (experimental
session), the drinking water is withdrawn. The conditioned rats are
divided into two groups (one animal per cage for either group).
Animals from the first group receive an intraperitoneal injection
of sodium salicylate (350 mg/kg bw) while animals from the second
group receive an intraperitoneal injection of an equivalent volume
of saline. Animals from either group are tested on the same day in
a semi-random order exactly 3 h after injection. During the
experimental session electrical stimuli are omitted. Four minutes
after the start of a session the sugar water reward is stopped and
the behavioral performances are recorded from 12-16 min and
subsequently analyzed. Within the next 2-5 days rats receive the
same training as before the experiment. On the next experimental
day animals from the group previously treated with salicylate are
injected with saline or test compound and tested again.
[0507] Frequencies of feeder access action of a rat are calculated
for periods of sound and periods of silence separately
(accesses/min) and normalized (SA activity ratio). The difference
of silence activity ratios (ASA ratio) is determined as the silence
activity ratio of an animal tested after salicylate injection less
the silence activity ratio of the same animal after saline
injection. Data is analyzed using appropriate statistical
methods.
[0508] During the training procedure, animals are conditioned to
discriminate between periods of sound and periods of silence using
auditory cues.
[0509] To induce phantom auditory sensations, animals are injected
with salicylate (350 mg/kg bw) or an equivalent volume of saline
and tested 3 h later. The SA ratio of animals treated with
salicylate is significantly higher than the SA ratio for animals
treated with saline.
[0510] Test compounds can be administered and their ability to
reverse the effects of the salicylate induced phantom auditory
sensations determined. Compounds that reduce the increase in the SA
ratio following in the salicylate treated animals can have
potential in treating tinnitus.
Description 7
Method for Assessing Therapeutic Efficacy of Acamprosate Prodrugs
for Treating Tinnitus in Humans
[0511] The efficacy of acamprosate prodrugs of Formula (I) for
treating tinnitus in humans can be assessed using methods known in
the art.
[0512] Patients are screened using pre-established inclusion and
exclusion criteria and selected for their ability to perform a
psychophysical loudness matching task using pure tones and
broad-band noise (BBN). Examples of inclusion criteria include, for
example, age, type of tinnitus, e.g., continuous or pulsed,
duration of tinnitus, Tinnitus Handicap Questionnaire (THQ)
score>30, Beck Depression Index (BDI)<13, and criterion
performance on loudness matching task using a 1 KHz standard.
[0513] Following screening, selection and enrollment, tinnitus is
evaluated before and after an acamprosate prodrug is administered
to a patient. Hearing thresholds are evaluated using an objective
stimulus loudness match and a tinnitus loudness matching
procedure.
[0514] Prior to enrollment, subjects are screened for proficiency
in a psychophysical matching task. In the objective stimulus
loudness matching procedure, subjects match a binaural 1 KHz
standard tone at 20 dB sensation levels to each of five binaural
comparison stimuli (BBN, 0.5, 1, 2, and 4 KHz). The loudness match
is obtained using a forced two-choice procedure. Each trial begins
with the simultaneous presentation of a visual cue and the 1 KHz
standard followed by the presentation of the second visual cue and
the comparison stimulus. Subjects are instructed to indicate
whether the standard and comparison stimuli sound the "same" or
"different" in loudness by clicking an on-screen button. An
ascending-descending method of limits procedure is used. Subjects
are screened using this loudness-matching test and are required to
meet inclusion criteria of efficiency (completion time.ltoreq.1 h)
and reliability (standard deviation of match levels.ltoreq.5
dB).
[0515] The tinnitus loudness matching procedure differs from the
objective stimulus loudness matching procedure in that the initial
presentation on each trial is a null presentation during which an
on-screen message instructs subjects to listen closely to their
tinnitus. During this initial 1-sec cue subjects are instructed to
use their perception of tinnitus as the standard stimulus. Subjects
are instructed to click a "same loudness" button when the loudness
of the comparison stimulus matches the loudness of their tinnitus.
The presentation order of the comparison stimuli (BBN, 0.5, 1, 2,
and 4 KHz) is randomized, and each ascending and descending
stimulus series is repeated once, for a total of four tinnitus
loudness matches at each of the five 1comparison stimuli. The
intensities of the loudness-match points are recorded and converted
to sensation levels of tinnitus loudness using the hearing
threshold determined in each session for the comparison stimuli.
Psychoacoustically determined tinnitus loudness is reported as dB
HL of the maximum sensation-level match obtained within a
session.
[0516] Assessment sessions are performed at the initiation of the
study and at intervals during the study. Subjects can be given
placebo only, an acamprosate prodrug only, a variable including
escalating or deescalating dose of an acamprosate prodrug, or a
combination of placebo and acamprosate prodrug during the course of
a study. The duration of the study can be a few hours, days, weeks,
months, or years.
[0517] Primary outcome measures are psychoacoustically determined
tinnitus loudness and perceived tinnitus handicap. Tinnitus
handicap can be determined using the Tinnitus Handicap
Questionnaire, which provides a global score and subscores related
to emotional, functional, and cognitive aspects of tinnitus.
Secondary outcome measures include general health and quality of
life factors determined using, for example, the General Health
Survey Short form (RAND 36-Item Health Survey, 1.0, Rand Health,
Santa Monica, Calif.) and the Tinnitus Experience Questionnaire, a
set of seven scaled questions that evaluate the experiential
sensory features of tinnitus. Other questionnaires for assessing
tinnitus can be used.
Description 8
Animal Model for Assessing Therapeutic Efficacy of Acamprosate
Prodrugs for Treating Sleep Apnea
[0518] Sprague-Dawley rats are anesthetized and a surgical incision
of the scalp is made to allow bilateral implantation of stainless
steel screws into the frontal and parietal bones of the skull for
electroencephalogram (EEG) recording. Bilateral wire electrodes are
placed into the nuchal muscles for electromyogram (EMG) recording.
The skin is then sutured and the animals allowed at least 7 days
for recovery. Respirations are recorded by placing each rat inside
a single chamber plethysmograph. The plethysmograph chamber is
flushed with room air at a constant regulated flow rate of 2 L/min.
EEG, EMG and respirations are continuously recorded. Sleep apneas
are defined as cessation of respiratory effort for at least 2.5 s.
The effects of recording hour, sleep state, and acamprosate prodrug
administration are analyzed using appropriate statistical
methods.
Description 9
Study for Assessing the Therapeutic Efficacy of Acamprosate
Prodrugs for Treating Sleep Apnea in Humans
[0519] Inclusion criteria are an apnea-hypopnea index (AHI)
exceeding 20 based on self-rated sleep duration at previous
unattended ventilatory screening or an AHI exceeding 25 in a
previous polysomnographic (PSG) recording. A double blind,
randomized, placebo-controlled cross-over study comparing the
effects of an acamprosate prodrug and placebo is used. Each patient
undergoes a complete PSG recording for habituation at night 1.
Patients are randomized to receive acamprosate prodrug on night 2
and placebo on night 3, or vice versa. Night 2 is scheduled within
1-21 days after night 1 and night 3 within 7-28 days after night 1
to provide a minimum of 7 days between night 2 and night 3 washout.
A complete PSG recording, physical examination, and recording of
ECG is performed in an identical manner at all study nights. Blood
samples are obtained in the morning after study nights for
hematology and clinical chemistry. Adverse events are determined by
active questioning. AHI, the number of obstructive apneic/hyponeic
events per time, is the primary efficacy variable. Secondary
efficacy variables are REM AHI, non-REM AHI, apnea index (AI),
hypopnea index (HI), oxygen desaturation index (ODI), minimum
overnight oxygen saturation, sleep stage distribution arousal
index, REM sleep and slow wave sleep latency, safety and
tolerability. An obstructive apnea is defined as loss of nasal
pressure accompanied by paradoxical respiratory movements for
>10 s. An obstructive hypopnea is defined as a >50% reduction
of the nasal pressure signal, but accompanied by chest wall
paradoxical motion through most of inspiration for >10 s. Events
without respiratory movements are classified as central apneas.
Description 10
Animal Models for Assessing Therapeutic Efficacy of Acamprosate
Prodrugs for Treating Parkinson's Disease
MPTP Induced Neurotoxicity
[0520] MPTP, or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine is a
neurotoxin that produces a Parkinsonian syndrome in both man and
experimental animals. Studies of the mechanism of MPTP
neurotoxicity show that it involves the generation of a major
metabolite, MPP.sup.+, formed by the activity of monoamine oxidase
on MPTP. Inhibitors of monoamine oxidase block the neurotoxicity of
MPTP in both mice and primates. The specificity of the neurotoxic
effects of MPP.sup.+ for dopaminergic neurons appears to be due to
the uptake of MPP.sup.+ by the synaptic dopamine transporter.
Blockers of this transporter prevent MPP.sup.+ neurotoxicity.
MPP.sup.+ has been shown to be a relatively specific inhibitor of
mitochondrial complex I activity, binding to complex 1 at the
retenone binding site and impairing oxidative phosphorylation. In
vivo studies have shown that MPTP can deplete striatal ATP
concentrations in mice. It has been demonstrated that MPP.sup.+
administered intrastriatally to rats produces significant depletion
of ATP as well as increased lactate concentration confined to the
striatum at the site of the injections. Compounds that enhance ATP
production can protect against MPTP toxicity in mice.
[0521] A prodrug of Formula (I) is administered to mice or rats for
three weeks before treatment with MPTP. MPTP is administered at an
appropriate dose, dosing interval, and mode of administration for 1
week before sacrifice. Control groups receive either normal saline
or MPTP hydrochloride alone. Following sacrifice the two striate
are rapidly dissected and placed in chilled 0.1 M perchloric acid.
Tissue is subsequently sonicated and aliquots analyzed for protein
content using a fluorometer assay. Dopamine,
3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA)
are also quantified. Concentrations of dopamine and metabolites are
expressed as nmol/mg protein.
[0522] Prodrugs of Formula (I) that protect against DOPAC depletion
induced by MPTP, HVA, and/or dopamine depletion are neuroprotective
and therefore can be useful for the treatment of Parkinson's
disease.
Haloperidol-Induced Hypolocomotion
[0523] The ability of a compound to reverse the behavioral
depressant effects of dopamine antagonists such as haloperidol in
rodents and is considered a valid method for screening drugs with
potential antiparkinsonian effects. Hence, the ability of prodrugs
of Formula (I) to block haloperidol-induced deficits in locomotor
activity in mice can be used to assess both in vivo and potential
anti-Parkinsonian efficacy.
[0524] Mice used in the experiments are housed in a controlled
environment and allowed to acclimatize before experimental use. 1.5
h before testing, mice are administered 0.2 mg/kg haloperidol, a
dose that reduces baseline locomotor activity by at least 50%. A
test compound is administered 5-60 min prior to testing. The
animals are then placed individually into clean, clear
polycarbonate cages with a flat perforated lid. Horizontal
locomotor activity is determined by placing the cages within a
frame containing a 3.times.6 array of photocells interfaced to a
computer to tabulate beam interrupts. Mice are left undisturbed to
explore for 1 h, and the number of beam interruptions made during
this period serves as an indicator of locomotor activity, which is
compared with data for control animals for statistically
significant differences.
6-Hydroxydopamine Animal Model
[0525] The neurochemical deficits seen in Parkinson's disease can
be reproduced by local injection of the dopaminergic neurotoxin,
6-hydroxydopamine (6-OHDA) into brain regions containing either the
cell bodies or axonal fibers of the nigrostriatal neurons. By
unilaterally lesioning the nigrostriatal pathway on only one-side
of the brain, a behavioral asymmetry in movement inhibition is
observed. Although unilaterally-lesioned animals are still mobile
and capable of self maintenance, the remaining dopamine-sensitive
neurons on the lesioned side become supersensitive to stimulation.
This is demonstrated by the observation that following systemic
administration of dopamine agonists, such as apomorphine, animals
show a pronounced rotation in a direction contralateral to the side
of lesioning. The ability of compounds to induce contralateral
rotations in 6-OHDA lesioned rats has been shown to be a sensitive
model to predict drug efficacy in the treatment of Parkinson's
disease.
[0526] A 2 cm long incision is made along the midline of the scalp
and the skin retracted and clipped back to expose the skull. A
small hole is then drilled through the skull above the injection
site. In order to lesion the nigrostriatal pathway, the injection
cannula is slowly lowered to position above the right medial
forebrain bundle at -3.2 mm anterior posterior, -1.5 mm medial
lateral from the bregma, and to a depth of 7.2 mm below the
duramater. Two minutes after lowering the cannula, 6-OHDA is
infused at a rate of 0.5 .mu.L/min over 4 min, to provide a final
dose of 8 .mu.g. The cannula is left in place for an additional 5
min to facilitate diffusion before being slowly withdrawn. The skin
is closed, the animal removed from the sterereotaxic frame, and
returned to its housing. The rats are allowed to recover from
surgery for two weeks before behavioral testing.
[0527] Rotational behavior is measured using a rotameter system
having stainless steel bowls (45 cm dia.times.15 cm high) enclosed
in a transparent Plexiglas cover around the edge of the bowl and
extending to a height of 29 cm. To assess rotation, rats are placed
in a cloth jacket attached to a spring tether connected to an
optical rotameter positioned above the bowl, which assesses
movement to the left or right either as partial (45.degree.) or
full (360.degree.) rotations.
[0528] To reduce stress during administration of a test compound,
rats are initially habituated to the apparatus for 15 min on four
consecutive days. On the test day, rats are given a test compound,
e.g., a prodrug of Formula (I). Immediately prior to testing,
animals are given a subcutaneous injection of a subthreshold dose
of apomorphine, and then placed in the harness and the number of
rotations recorded for one hour. The total number of full
contralatral rotations during the hour test period serves as an
index of antiparkinsonian drug efficacy.
L-Dopa Induced Dyskinesia
[0529] The ability of acamprosate prodrugs to mitigate the effects
of L-dopa induced dyskinesia can be assessed using animal
models.
[0530] Male, Sprague-Dawley rats (250-300 g) are housed and
maintained under standard conditions.
[0531] Reserpine (4 mg/kg) is administered under light isofluorane
anesthesia. Eighteen hours following reserpine administration, the
animals are placed into observation cages. Behavior is assessed
using an automated movement detection system that includes dual
layers of rectangular grids of sensors containing an array of 24
infrared beams surrounding the cage. Each beam break is registered
as an activity count and contributes to the assessment of a variety
of different behavioral parameters depending on the location of the
event and the timing of successive beam breaks. These parameters
include: (1) horizontal activity, a measure of the number of beams
broken on the lower level; and (2) vertical activity, a measure of
beams broken on the upper level.
[0532] In one experiment, immediately prior to commencing
behavioral assessments, rats are injected with a combination of
L-dopa methyl ester and carbidopa (or benserazide). In another
study, to assess the effects of acamprosate prodrugs on L-dopa
induced activity, animals are randomly assigned to groups. In each
group, immediately following L-dopa/carbidopa administration,
vehicle or acamprosate prodrug is administered. The behavior of
normal, non-resperine-treated, animals is also assessed. Behavior
of the animals in the different groups is monitored for at least 4
hours. Acamprosate prodrugs that reduce the L-dopa-induced
locomotion in the reserpine-treated rats are potentially useful in
treating Parkinson's disease and/or the symptoms associated with
Parkinson's disease.
Description 11
Use of Clinical Trials to Assess the Efficacy of Acamprosate
Prodrugs for Treating Parkinson's Disease
[0533] The following clinical study may be used to assess the
efficacy of a compound in treating Parkinson's disease.
[0534] Patients with idiopathic PD fulfilling the Queen Square
Brain Bank criteria with motor fluctuations and a defined short
duration GABA analog response (1.5-4 hours) are eligible for
inclusion. Clinically relevant peak dose dyskinesias following each
morning dose of their current medication are a further
pre-requisite. Patients are also required to have been stable on a
fixed dose of treatment for a period of at least one month prior to
starting the study. Patients are excluded if their current drug
regime includes slow-release formulations of L-Dopa, COMT
inhibitors, selegiline, anticholinergic drugs, or other drugs that
could potentially interfere with gastric absorption (e.g.
antacids). Other exclusion criteria include patients with psychotic
symptoms or those on antipsychotic treatment, patients with
clinically relevant cognitive impairment, defined as MMS (Mini
Mental State) score of less than 24, risk of pregnancy, Hoehn &
Yahr stage 5 in off-status, severe, unstable diabetes mellitus, and
medical conditions such as unstable cardiovascular disease or
moderate to severe renal or hepatic impairment. Full blood count,
liver, and renal function blood tests are taken at baseline and
after completion of the study.
[0535] A randomized, double blind, and cross-over study design is
used. Each patient is randomized to the order in which either
L-dopa or one of the two dosages of test compound, e.g., an
acamprosate prodrug, is administered in a single-dose challenge in
double-dummy fashion in three consecutive sessions. Randomization
is by computer generation of a treatment number, allocated to each
patient according to the order of entry into the study. All
patients give informed consent.
[0536] Patients are admitted to a hospital for an overnight stay
prior to administration of test compound the next morning on three
separate occasions at weekly intervals. After withdrawal of all
antiparkinsonian medication from midnight the previous day, test
compound is administered at exactly the same time in the morning in
each patient under fasting conditions.
[0537] Patients are randomized to the order of the days on which
they receive placebo or test compound. The pharmacokinetics of a
test compound can be assessed by monitoring plasma acamprosate
concentration over time. Prior to administration, a 22 G
intravenous catheter is inserted in a patient's forearm. Blood
samples of 5 ml each are taken at baseline and 15, 30, 45, 60, 75,
90, 105, 120, 140, 160, 180, 210, and 240 minutes after
administering a test compound or until a full off state has been
reached if this occurs earlier than 240 minutes after drug
ingestion. Samples are centrifuged immediately at the end of each
assessment and stored deep frozen until assayed. Plasma acamprosate
levels are determined by high-pressure liquid chromatography
(HPLC). On the last assessment additional blood may be drawn for
routine hematology, blood sugar, liver, and renal function.
[0538] For clinical assessment, motor function is assessed using
the United Parkinson's Disease Rating Scale motor score and
BrainTest, which is a tapping test performed with a patient's more
affected hand on the keyboard of a laptop computer. These tests are
carried out at baseline and then immediately following each blood
sample until patients reach their full on-stage, and thereafter at
3 intervals of 20 min, and 30 min intervals until patients reach
their baseline off-status. Once patients reach their full on-state,
video recordings are performed three times at 20 min intervals. The
following mental and motor tasks, which have been shown to increase
dyskinesia, are monitored during each video session: (1) sitting
still for 1 minute; (2) performing mental calculations; (3) putting
on and buttoning a coat; (4) picking up and drinking from a cup of
water; and (5) walking. Videotapes are scored using, for example,
versions of the Goetz Rating Scale and the Abnormal Involuntary
Movements Scale to document a possible increase in test compound
induced dyskinesia.
[0539] Occurrence and severity of dyskinesia is measured with a
Dyskinesia Monitor. The device is taped to a patient's shoulder on
their more affected side. The monitor records during the entire
time of a challenging session and provides a measure of the
frequency and severity of occurring dyskinesias.
[0540] Results can be analyzed using appropriate statistical
methods.
Description 12
Use of Clinical Trials to Assess the Efficacy of Acamprosate
Prodrugs for Treating Levodopa-Induced Dyskinesias in Parkinson's
Disease
[0541] A double-blind placebo-controlled clinical trial such as
that described by Goetz et al., Movement Disorders 2007, 22(2),
179-186 can be used to assess the efficacy of an acamprosate
prodrug for treating levodopa-induced dyskinesias in Parkinson's
disease.
[0542] Patients are 30 years of age or older with Parkinson's
disease and received levodopa treatment at a stable (at least 4
weeks) and optimized dose. Following enrollment, patients are
randomized and receive either placebo or an appropriate dose and
regimen of acamprosate prodrug. Levodopa doses are maintained at
the baseline level. At appropriate intervals during the study,
patients are evaluated for periods during the day characterized by
sleep, off, on-without dyskinesias, on-with non-troublesome
dyskinesias, and on-with troublesome dyskinesia. The primary
outcome is change from baseline in on-time without dyskinesia.
Various dyskinesia rating scales such as, for example, the Abnormal
Involuntary Movement Scale, Unified Parkinson's Disease Rating
Scale (UPDRS) Motor examination (Part III), or UPDRS Activities of
Daily Living assessment (Part III) can also be used. Measures of
safety such as frequency and severity of reported adverse events,
changes in vital signs, laboratory test results, including
ACTH-suppression testing of cortisol levels and electrocardiogram
can also be determined.
Description 13
Animal Model for Assessing Therapeutic Efficacy of Acamprosate
Prodrugs for Treating Alzheimer's Disease
[0543] Heterozygous transgenic mice expressing the Swedish AD
mutant gene, hAPPK670N, M671L (Tg2576) are used as an animal model
of Alzheimer's disease. Beginning at 9 months of age, mice are
divided into two groups. The first two groups of animals receive
increasing doses of an acamprosate prodrug, over six weeks. The
remaining control group receives daily saline injections for six
weeks.
[0544] Behavioral testing is performed at each drug dose using the
same sequence over two weeks in all experimental groups: (I)
spatial reversal learning, (2) locomotion, (3) fear conditioning,
and (4) shock sensitivity. This order is selected to minimize
interference among testing paradigms.
[0545] Acquisition of the spatial learning paradigm and reversal
learning are tested during the first five days of test compound
administration using a water T-maze. Mice are habituated to the
water T-maze during days 1-3, and task acquisition begins on day 4.
On day 4, mice are trained to find the escape platform in one
choice arm of the maze until 6 to 8 correct choices are made on
consecutive trails. The reversal learning phase is then conducted
on day 5. During the reversal learning phase, mice are trained to
find the escape platform in the choice arm opposite from the
location of the escape platform on day 4. The same performance
criterion and inter-trial interval are used as during task
acquisition.
[0546] Large ambulatory movements are assessed to determine that
the results of the spatial reversal learning paradigm are not
influenced by the capacity for ambulation. After a rest period of
two days, horizontal ambulatory movements, excluding vertical and
fine motor movements, are assessed in a chamber equipped with a
grid of motion-sensitive detectors on day 8. The number of
movements accompanied by simultaneous blocking and unblocking of a
detector in the horizontal dimension are measured during a one-hour
period.
[0547] The capacity of an animal for contextual and cued memory is
tested using a fear conditioning paradigm beginning on day 9.
Testing takes place in a chamber that contains a piece of absorbent
cotton soaked in an odor-emitting solution such as mint extract
placed below the grid floor. A 5-min, 3 trial 80 db, 2800 Hz
tone-foot shock sequence is administered to train the animals on
day 9. On day 10, memory for context is tested by returning each
mouse to the chamber without exposure to the tone and foot shock,
and recording the presence or absence of freezing behavior every 10
seconds for 8 minutes. Freezing is defined as no movement, such as
ambulation, sniffing or stereotypy, other than respiration.
[0548] On day 11, the response of the animal to an alternate
context and to the auditory cue is tested. Coconut extract is
placed in a cup and the 80 dB tone is presented, but no foot shock
is delivered. The presence or absence of freezing in response to
the alternate context is then determined during the first 2 minutes
of the trial. The tone is then presented continuously for the
remaining 8 minutes of the trial, and the presence or absence of
freezing in response to the tone is determined. On day 12, the
animals are tested to assess their sensitivity to the conditioning
stimulus, i.e., foot shock. Following the last day of behavioral
testing, animals are anesthetized and the brains removed,
post-fixed overnight, and sections cut through the hippocampus. The
sections are stained to image .beta.-amyloid plaques (.
[0549] Data are analyzed using appropriate statistical methods.
Description 14
Animal Model for Assessing Therapeutic Efficacy of Acamprosate
Prodrugs for Treating Huntington's Disease
Neuroprotective Effects in a Transgenic Mouse Model of Huntington
's Disease
[0550] Transgenic HD mice of the N171-82Q strain and non-transgenic
littermates are treated with a prodrug of Formula (I) or a vehicle
from 10 weeks of age. The mice are placed on a rotating rod
("rotarod"). The length of time at which a mouse falls from the
rotarod is recorded as a measure of motor coordination. The total
distance traveled by a mouse is also recorded as a measure of
overall locomotion. Mice administered prodrugs of Formula (I) that
are neuroprotective in the N 171-82Q transgenic HD mouse model
remain on the rotarod for a longer period of time and travel
further than mice administered vehicle.
Malonate Model of Huntington 's Disease
[0551] A series of reversible and irreversible inhibitors of
enzymes involved in energy generating pathways has been used to
generate animal models for neurodegenerative diseases such as
Parkinson's and Huntington's diseases. In particular, inhibitors of
succinate dehydrogenase, an enzyme that impacts cellular energy
homeostasis, has been used to generate a model for Huntington's
disease. The enzyme succinate dehydrogenase plays a central role in
both the tricarboxylic acid cycle as well as the electron transport
chain in mitochondria. Malonate is a reversible inhibitor of
succinate dehydrogenase. Intrastriatal injections of malonate in
rats have been shown to produce dose dependent striatal excitotoxic
lesions that are attenuated by both competitive and noncompetitive
NMDA antagonists. For example, the glutamate release inhibitor,
lamotrigine, also attenuates the lesions. Co-injection with
succinate blocks the lesions, consistent with an effect on
succinate dehydrogenase. The lesions are accompanied by a
significant reduction in ATP levels as well as a significant
increase in lactate levels in vivo as shown by chemical shift
resonance imaging. The lesions produce the same pattern of cellular
sparing, which is seen in Huntington's disease, supporting malonate
challenge as a useful model for the neuropathologic and
neurochemical features of Huntington's disease.
[0552] To evaluate the effect of acamprosate prodrugs of Formula
(1) in this malonate model for Huntington's disease, a prodrug of
Formula (I) is administered at an appropriate dose, dosing
interval, and route, to male Sprague-Dawley rats. A prodrug is
administered for two weeks prior to the administration of malonate
and then for an additional week prior to sacrifice. Malonate is
dissolved in distilled deionized water and the pH adjusted to 7.4
with 0.1 M HCl. Intrastriatal injections of 1.5 .mu.L of 3 .mu.mol
malonate are made into the left striatum at the level of the Bregma
2.4 mm lateral to the midline and 4.5 mm ventral to the dura.
Animals are sacrificed at 7 days by decapitation and the brains
quickly removed and placed in ice cold 0.9% saline solution. Brains
are sectioned at 2 mm intervals in a brain mold. Slices are then
placed posterior side down in 2% 2,3,5-tiphenyltetrazolium
chloride. Slices are stained in the dark at room temperature for 30
min and then removed and placed in 4% paraformaldehyde pH 7.3.
Lesions, noted by pale staining, are evaluated on the posterior
surface of each section. The measurements are validated by
comparison with measurements obtained on adjacent Nissl stain
sections. Compounds exhibiting a neuroprotective effect and
therefore potentially useful in treating Huntington's disease show
a reduction in malonate-induced lesions.
Description 15
Animal Model for Assessing Therapeutic Efficacy of Acamprosate
Prodrugs for Treating Amyotrophic Lateral Sclerosis
[0553] A murine model of SODI mutation-associated ALS has been
developed in which mice express the human superoxide dismutase
(SOD) mutation glycine.fwdarw.alanine at residue 93 (SOD1). These
SOD1 mice exhibit a dominant gain of the adverse property of SOD,
and develop motor neuron degeneration and dysfunction similar to
that of human ALS. The SOD1 transgenic mice show signs of posterior
limb weakness at about 3 months of age and die at 4 months.
Features common to human ALS include astrocytosis, microgliosis,
oxidative stress, increased levels of cyclooxygenase/prostaglandin,
and, as the disease progresses, motor neuron loss.
[0554] Studies are performed on transgenic mice overexpressing
human Cu/Zn--SOD G93A mutations ((B6SJL-TgN (SOD1-G93A) 1 Gur)) and
non-transgenic B6/SJL mice and their wild litter mates. Mice are
housed on a 12-hr day/light cycle and (beginning at 45 d of age)
allowed ad libitum access to either test compound-supplemented
chow, or, as a control, regular formula cold press chow processed
into identical pellets. Genotyping can be conducted at 21 days of
age. The SOD1 mice are separated into groups and treated with a
test compound, e.g., an acamprosate prodrug, or serve as
controls.
[0555] The mice are observed daily and weighed weekly. To assess
health status mice are weighed weekly and examined for changes in
lacrimation/salivation, palpebral closure, ear twitch and pupillary
responses, whisker orienting, postural and righting reflexes and
overall body condition score. A general pathological examination is
conducted at the time of sacrifice.
[0556] Motor coordination performance of the animals can be
assessed by one or more methods known to those skilled in the art.
For example, motor coordination can be assessed using a
neurological scoring method. In neurological scoring, the
neurological score of each limb is monitored and recorded according
to a defined 4--point scale: 0--normal reflex on the hind limbs
(animal will splay its hind limbs when lifted by its tail);
1--abnormal reflex of hind limbs (lack of splaying of hind limbs
weight animal is lifted by the tail); 2--abnormal reflex of limbs
and evidence of paralysis; 3--lack of reflex and complete
paralysis; and 4--inability to right when placed on the side in 30
seconds or found dead. The primary end point is survival with
secondary end points of neurological score and body weight.
Neurological score observations and body weight are made and
recorded five days per week. Data analysis is performed using
appropriate statistical methods.
[0557] The rotarod test evaluates the ability of an animal to stay
on a rotating dowel allowing evaluation of motor coordination and
proprioceptive sensitivity. The apparatus is a 3 cm diameter
automated rod turning at, for example, 12 rounds per min. The
rotarod test measures how long the mouse can maintain itself on the
rod without falling. The test can be stopped after an arbitrary
limit of 120 sec. Should the animal fall down before 120 sec, the
performance is recorded and two additional trials are performed.
The mean time of 3 trials is calculated. A motor deficit is
indicated by a decrease of walking time.
[0558] In the grid test, mice are placed on a grid (length: 37 cm,
width: 10.5 cm, mesh size: 1.times.1 cm.sup.2) situated above a
plane support. The number of times the mice put their paws through
the grid is counted and serves as a measure for motor
coordination.
[0559] The hanging test evaluates the ability of an animal to hang
on a wire. The apparatus is a wire stretched horizontally 40 cm
above a table. The animal is attached to the wire by its forepaws.
The time needed by the animal to catch the string with its hind
paws is recorded (60 sec max) during three consecutive trials.
[0560] Electrophysiological measurements (EMG) can also be used to
assess motor activity condition. Electromyographic recordings are
performed using an electromyography apparatus. During EMG
monitoring mice are anesthetized. The measured parameters are the
amplitude and the latency of the compound muscle action potential
(CMAP). CMAP is measured in gastrocnemius muscle after stimulation
of the sciatic nerve. A reference electrode is inserted near the
Achilles tendon and an active needle placed at the base of the
tail. A ground needle is inserted on the lower back of the mice.
The sciatic nerve is stimulated with a single 0.2 msec pulse at
supramaximal intensity (12.9 mA). The amplitude (mV) and the
latency of the response (ms) are measured. The amplitude is
indicative of the number of active motor units, while distal
latency reflects motor nerve conduction velocity.
[0561] The efficacy of test compounds can also be evaluated using
biomarker analysis. To assess the regulation of protein biomarkers
in SODI mice during the onset of motor impairment, samples of
lumbar spinal cord (protein extracts) are applied to ProteinChip
Arrays with varying surface chemical/biochemical properties and
analyzed, for example, by surface enhanced laser desorption
ionization time of flight mass spectrometry. Then, using integrated
protein mass profile analysis methods, data is used to compare
protein expression profiles of the various treatment groups.
Analysis can be performed using appropriate statistical
methods.
Description 16
Assessing Therapeutic Efficacy of Acamprosate Prodrugs for Treating
Cortical Spreading Depression
[0562] It has been hypothesized that cortical spreading depression
emanating from a site of injury causes secondary damage in the
"penumbra" by disrupting ion homeostasis and producing demands on
neurons already in a compromised state. Focal CNS injury or
ischemia also results in an induction of the immediate early gene
c-fos. c-fos induction spreads throughout the injured hemisphere by
a process that appears to be dependent on cortical spreading
depression. c-fos induction is inhibited by NMDA receptor
antagonists. Thus, both cortical spreading depression and c-fos
induction are NMDA receptor activated processes associated with CNS
injury and may be components of the cascade leading to neuron
death.
[0563] NMDA-induced increase in fos immunoreactivty in mice is
determined according to the following protocol. Male CF-1 mice (20
to 25 g) are administered varying doses of an acamprosate prodrug
or vehicle. Thirty min later, animals receive intraperitioneal
administration of NMDA (75 mg/kg) or vehicle. Sixty min later,
animals are terminally anesthetized, brains are removed to ice and
immersed for 1 h in 2% paraformaldehyde in phosphate buffered
saline, and transferred to 15% sucrose in phosphate buffered
saline, incubated overnight, and then frozen at -80.degree. C.
Coronal sections through the hippocampal region are taken, washed,
and incubated with a sheep anti-fos polyclonal antibody (OA-11-824)
for 18 h at 4.degree. C. Sections are washed with phosphate
buffered saline and then incubated with biotinylated rabbit
anti-sheep antibody for 2 h. After 3 washes in phosphate buffered
saline, sections are incubated in Vector ABC solution for 1 h at
25.degree. C., washed 3 times, stained for glucose oxidase, and
mounted. Each section is photographed and the intensity of fos-like
immunoreactivity in the dentate gyrus is analyzed.
[0564] CNS trauma-induced c-fos mRNA induction in rats is
determined according to the following protocol. Male Sprague-Dawley
rats (200-250 g) are administered different doses of an acamprosate
prodrug or vehicle. After 30 min, animals are anesthetized and a
burr hole drilled over the right frontal parietal cortex 3 mm
anterior and 3 mm lateral to bregma. An 18-gauge needle is inserted
through the hole for 2 min to a depth of about 3 mm into the
cortex. After a 60 min recovery animals are sacrificed, the brains
removed, and cortices dissected and frozen in liquid nitrogen.
Changes in c-fos mRNA expression following needle injury are
quantified using procedures known in the art.
[0565] To assess the effects of acamprosate prodrugs on
electrically-induced cortical spreading depression in rats, male
Sprague-Dawley rats (275-325 g) are anaesthetized. The
spontaneously breathing animals are fixed in a stereotaxic frame, a
craniotomy is drilled over the parietal cortex, and the dura is
removed. Two saline-filled glass recording microelectrodes each
containing a Ag/AgCl wire are inserted into the parietal cortex at
a depth of about 1 mm and 1.5-2.0 mm apart along the sagital plane
using a micromanipulator. Two saline filled cannulae each
containing a Ag/AgCl wire are inserted under the skin of the animal
to serve as reference electrodes. Cortical spreading depression is
induced in the parietal cortex using a bipolar stimulating
electrode placed at 90.degree. to the frontal recording electrode
and positioned so that the electrode visibly touches but does not
depress the cortex. Electrocortical stimulation consists of a train
of 5 ms pulses at 40 Hz lasting for 2 s. The threshold stimulation
for cortical spreading depression determined by varying the
current. Once the threshold current has been determined, the
current is increased by 20% for experimental measurements. DC
potentials are recorded at 10 min intervals for four control
stimulations. An acamprosate prodrug is then administered. DC
potentials are again recorded at 10 min intervals. The speed of
cortical spreading depression expansion is calculated from the
latency difference of the negative DC shift at the rostral and
caudal electrodes.
Description 17
Animal Models to Assess the Efficacy of Acamprosate Prodrugs for
Treating Migraine
[0566] Therapeutic activity of acamprosate prodrugs provided by the
present disclosure may be determined in various animal models of
neuropathic pain or in clinically relevant studies of different
types of neuropathic pain. Animal models for neuropathic pain are
known in the art and include animal models that determine analgesic
activity or compounds that act on the CNS to reduce the phenomenon
of central sensitization that results in pain from nonpainful or
nonnoxious stimuli. Other animal models that are known in the art,
such as hot plate tests, model acute pain, are useful for
determining analgesic properties of compounds that are effective
when painful or noxious stimuli are present. The progression of
migraines is believed to be similar to the progression of epilepsy
(because an episodic phenomenon underlies the initiation of the
epileptic episode) and, as such, it is believed that epilepsy
animal models may be useful in determining efficacy in treating
migraine. Analgesic Activity
[0567] The following test can be used to evaluate the analgesic
activity of an acamprosate prodrug. Test compound is administered
orally to mice. Morphine is administered as a reference substance
at 64 mg/kg to mice under the same experimental conditions. A
vehicle is administered to mice as a control substance under the
same experimental conditions. Test compound, morphine, or vehicle
is administered to the mice in a blind study. Sixty minutes after
the test compound, morphine, or vehicle is administered, the mice
are placed onto a hot metal plate maintained at 54.degree. C. and
surrounded by a Plexiglass cylinder. The time taken for the mice to
lick their feet is an index of analgesic activity. Effective
analgesics increase the latency or amount of time to licking.
Latency to the first foot lick is measured, up to a maximum time of
30 sec to prevent tissue damage to the mice.
Hyperreflexia and Flexor Reflex Tests
[0568] Assessment of hyperreflexia, pain, and muscle tone in
chronic spinally transected rats is performed using male albino
Holtzman-derived rats weighing 270-530 gm. The rats are housed
independently and have continuous access to food and water
throughout the experiments. Animals are anesthetized. Rats are
placed in a stereotaxic frame and anesthesia is maintained. An
incision is made so that the paraspinal muscles can be retracted
and a laminectomy performed between T6-T9. A one- to two-millimeter
portion of the spinal cord is removed by evacuation and replaced
with gel foam to reduce bleeding, after which the incision is
closed in layers.
[0569] Following the transection, rats are placed in a room in
which the ambient temperature is raised to about 27.degree. C. to
maintain body temperature. On the following morning post-surgery,
the hindquarters of the spinalized rats are bathed and their urine
expressed manually by applying pressure to their bladders.
Experiments are conducted between 21 and 28 days after surgery. For
the first two weeks post-surgery, 0.25 mL of an antibiotic is
administered to the rats to prevent bladder infection. A topical
antibiotic is applied to any part of the skin that shows signs of
decubitus lesions. Within approximately two weeks, all animals
regain bladder control and are no longer given antibiotic
treatment. Assessment of hyperreflexia and flexor reflex is
performed before and after treatment with test compound so that
each animal serves as its own control.
[0570] Initial assessment of hyperreflexia is performed by rating
the hyperreflexia response elicited with an innocuous stimulus,
such as a metal probe. A metal probe is pressed against the lower
abdomen at four specific sites. The response is evaluated for each
of four trials using a scale ranging from zero (no response in all
four trials) to four (a maximum, tonic-clonic reaction elicited in
all four trials). All scores, pre- and post-treatment, are
transformed to indicate the percent of hyperreflexia, pain, or
muscle tone. The data is analyzed using appropriate statistical
methods.
[0571] After determining hyperreflexia before drug treatment, test
compound is administered to the rats.
[0572] Polysynaptic flexor-reflex responses, elicited by stimuli
that activate high-threshold afferents, are recorded as EMG
activity from the ipsilateral hamstring muscle. Supramaximal
electric shocks are applied to the hindpaw and recording electrodes
are placed in the biceps femoris semitendinosus muscle. Five sets
of stimuli are made at each time point. The flexor reflex is
recorded, in periods with and without test compound, every 30 min
once a stable baseline response is achieved. The data at time zero
represent pre-treatment control values. The responses are
determined in spinalized rats by observing the flexor-reflex
response before treatment and at each of 30, 60, 90, and 120 min
following administration of test compound, baclofen (10 mg/kg sc),
or vehicle (water, 12 ml/kg po). Efficacy is indicated when a test
compound is shown to reduce the magnitude of the flexor-reflex
responses in a chronic spinalized rat at all time points with
similar efficacy to baclofen, the positive control.
Cutaneous Hypersensitivity Test
[0573] The effects of a test compound on nociceptive activation of
the trigeminovascular system is determined using an animal model of
migraine. A pharmaceutical composition comprising a test compound
is administered to cats. To serve as positive and negative
controls, a vehicle control is administered to the cats. Efficacy
is indicated for compounds that inhibit trigeminovascular
activation compared to the trigeminovascular activation in the cats
that receive the vehicle.
Yawning
[0574] Yawning is a behavior that has been linked to activation of
dopaminergic neurotransmission. Yawning is part of a behavioral
syndrome occurring in most patients during a migraine attack.
Blockage of quinipirole-induced yawning in rats has been used as an
animal model to study the potential antagonism of migraine
symptoms.
[0575] Male Sprague Dawley rats are acclimatized for 12 days before
testing and at the time of the study. The rats are housed in
standard size steel cages with four animals per cage and are
maintained on a 12 hour light/dark schedule. Test compound or
vehicle is administered 15 min before the dopamine D2 agonist
quinipirole in vehicle or the vehicle alone is administered to the
animals. The animals are then placed individually in 6 in.times.6
in plexiglass observation cages and the number of yawns is counted
for the subsequent 30 min. The data is analyzed by an appropriate
statistical method.
[0576] The dopamine D2 agonist quinipirole can produce an average
of 13-15 yawns per 30 minutes while no yawning behavior is
typically observed in vehicle treated animals. Compounds that
inhibit quinipirole-induced yawning may be efficacious in treating
migraine.
Animal Model of Dural Protein Extravasation
[0577] The following animal model can be employed to determine the
ability of an acamprosate prodrug to inhibit protein extravasation,
an exemplary functional assay of the neuronal mechanism of
migraine.
[0578] Rats or guinea pigs are anesthetized and placed in a
stereotaxic frame with the incisor bar set at -3.5 mm for rats or
-4.0 mm for guinea pigs. Following a midline sagital scalp
incision, two pairs of bilateral holes are drilled through the
skull (6 mm posteriorly, 2.0 and 4.0 mm laterally in rats; 4 mm
posteriorly and 3.2 and 5.2 mm laterally in guinea pigs, with all
coordinates referenced to bregma). Pairs of stainless steel
stimulating electrodes, insulated except at the tips are lowered
through the holes in both hemispheres to a depth of 9 mm (rats) or
10.5 mm (guinea pigs) from dura.
[0579] Test compound is administered. About 7 min later a
fluorescent dye (e.g., Evans Blue) is administered. The fluorescent
dye complexes with proteins in the blood and functions as a marker
for protein extravasation. Ten (10) min post-injection of the test
compound, the left trigeminal ganglion is stimulated for 3 minutes
at a current intensity of 1.0 mA (5 Hz, 4 msec duration) with a
potentiostat/galvanostat. Fifteen minutes following stimulation,
the animals are killed and exsanguinated with 20 mL of saline. The
top of the skull is removed to facilitate collection of the dural
membranes. Dural membrane samples are removed from both
hemispheres, rinsed with water, and spread flat on microscopic
slides. Once dried, the tissues are coverslipped with a 70%
glycerol/water solution. A fluorescence microscope equipped with a
grating monochromator and a spectrophotometer is used to quantify
the amount of fluorescent dye in each sample.
[0580] The extravasation induced by the electrical stimulation of
the trigeminal ganglion is an ipsilateral effect (i.e. occurs only
on the side of the dura in which the trigeminal ganglion is
stimulated). This allows the other (unstimulated) half of the dura
to be used as a control. The ratio of the amount of extravasation
in the dura from the stimulated side, over the amount of
extravasation in the unstimulated side, is calculated. Control
animals dosed with only saline, yield, for example, a ratio of
about 2.0 in rats and about 1.8 in guinea pigs. In contrast, a
compound that effectively prevents the extravasation in the dura
from the stimulated side yields a ratio of about 1.0. Dose-response
curves can be generated for a test compound and the dose that
inhibits the extravasation by 50% (ID.sub.50) or 100% (ID.sub.100)
can be determined.
Amygdala Kindling Model
[0581] A relationship has been reported between migraine, affective
illness and epilepsy. Although the three disorders are distinct,
they all are paroxysmal dysregulations of the nervous system that
partially overlap in their pharmacology. The kindling model for
complex-partial seizures is based on the progressive development of
seizures combined with electroencephalographic (EEG) paroxysmal
patterns induced by repeated initially subconvulsive electrical
stimulation of limbic structures, e.g., the basolateral nucleus of
the amygdala. Once established, the phenomenon persists for months.
Since the amygdala-kindled seizures in animals share numerous
characteristics with complex-partial seizures in humans, it is a
useful animal model of complex partial seizures. An advantage of
using the amygdala kindling model is that both behavioral and EEG
parameters of the partial and generalized seizures can be measured.
Furthermore, the amygdala kindling model is reported to be
appropriate for studying diseases such as migraine, affective
illness, and epilepsy which increase in severity over time and in a
manner which is related to the number of symptomatic episodes.
[0582] Rats are obtained at an age of 11-12 weeks (body weight
180-200 gm). Rats are maintained separately in plastic cages at
controlled temperature (23.degree. C.) and humidity (about 50% RH)
with a 12-h light cycle. The rats receive standard diet and tap
water ad libitum.
[0583] For implantation of stimulation and recording electrodes,
rats are anesthetized and receive stereotaxic implantation of one
bipolar electrode in the right basolateral amygdala. Coordinates
for electrode implantation are AP-2.2 mm, L-4.8 mm, V-8.5 mm. All
coordinates are measured from bregma. Skull screws serve as the
reference electrode. The electrode assembly is attached to the
skull by dental acrylic cement. After a postoperative period of 2
weeks, constant current stimulations (500 .mu.A, 1 ms, monophasic
square-wave pulses, 50/sec for 1 sec) are delivered to the amygdala
at intervals of 1/day until ten stage 5 seizures are elicited. The
electrical susceptibility of the stimulated region (threshold for
induction of afterdischarges) is recorded on the first day of the
experiment (initial afterdischarge threshold) as well as after
kindling acquisition (with an interval of at least 4 days after the
tenth stage 5 seizure) using an ascending staircase procedure. The
initial current intensity is 1 .mu.A, and the current intensity is
increased in steps of about 20% of the previous current at
intervals of 1 min until an afterdischarge of at least 3 sec
duration is elicited. In addition to afterdischarge threshold, the
following parameters of kindled seizures are measured in
fully-kindled rats after stimulation with the afterdischarge
threshold current: seizure severity is classified as follows:
1--immobility, eye closure, twitching of vibrissae, sniffing,
facial clonus; 2--head nodding associated with more severe facial
clonus; 3--clonus of one forelimb; 4--rearing, often accompanied by
bilateral forelimb clonus; and 5--rearing with loss of balance and
falling accompanied by generalized clonic seizures. Seizure
duration 1 is the duration of limbic (stage 1-2) and/or motor
seizures (stage 3-5). Seizure duration 2 includes the time of
limbic and/or motor seizures plus the adjacent time of immobility.
Afterdischarge duration 1 (ADD 1) is the time of spikes in the EEG
recorded from the site of stimulation with a frequency of at least
1/sec. Afterdischarge duration 2 (ADD 2) is the total time of
spikes occurring in the EEG including those, which followed the ADD
1 with lower frequency and amplitude.
[0584] Test compound is administered to the prepared animals.
Control experiments are performed 2-3 days before each test
compound experiment. For control determinations, rats receive
vehicle (e.g., saline) with the pretreatment time of the respective
test compound experiment. For all test compound experiments, at
least 4 days are interposed between successive administrations in
order to avoid alterations in drug potency due to cumulation or
tolerance. Data is analyzed using appropriate statistical
methods.
[0585] In addition to recordings of anticonvulsant parameters,
kindled rats can be observed for adverse effects in order to
estimate a therapeutic index. Tests include open field
observations, rotarod test, and body temperature. Tests used to
evaluate adverse effects are performed in the same manner in
control and test compound experiments at two different times,
immediately before application of a test compound or vehicle and 13
min after application.
[0586] The rotarod test is carried out with a rod of 6 cm diameter
and rotation speed of 8 rpm. Neurological deficit is indicated by
inability of the animals to maintain their equilibrium for at least
1 min on the rotating rod. Rats are trained prior to the rotarod
evaluation to maintain their balance on the rod. After treatment
with a test compound or vehicle, rats that are not able to maintain
their equilibrium on the rod for three subsequent 1 min attempts
are considered to exhibit neurological deficit.
[0587] In addition to these quantitative estimations of
neurological deficit, behavioral alterations after administration
of test compound are noted in the cage and after placing the
animals in an open field of 90-100 cm diameter. Muscle tone is
estimated by palpation of the abdomen. The extent of deficits in
behavior after administration of a test compound is determined by a
rating system. Animals are taken out of the cage, placed in an open
field, observed for about 1 minute and rated separately for ataxia,
abducted hindlimbs, reduced righting, flat body posture, circling,
Straub tail, piloerection, hypolocomotion and hyperlocomotion
(abdominal muscle tone is evaluated by palpation at the end of the
period of observation). All other parameters except ataxia are
scored from 0 to 3: 0--absent; 1--equivocal; 2--present;
3--intense. For ataxia: 1--slight ataxia in hind-legs (tottering of
the hind quarters); 2--more pronounced ataxia with dragging of hind
legs; 3--further increase of ataxia and more pronounced dragging of
hind legs; 4--marked ataxia, animals lose balance during forward
locomotion; 5--very marked ataxia with frequent loss of balance
during forward locomotion; and 6--permanent loss of righting
reflexes, but animal still attempts to move forward. Rectal body
temperature is measured. Body weight of the animals is recorded
once daily before a test compound is administered. Data is analyzed
by an appropriate statistical method. The ability of a test
compound to increase the electrical threshold for induction of
afterdischarges, decrease the severity of seizures, reduce seizure
duration, and reduce total afterdischarge duration suggests
efficacy in treating migraine.
Description 18
Use of Clinical Trials to Assess the Efficacy of Acamprosate
Prodrugs for Treating Migraine
[0588] The efficacy of a compound of Formula (I) in treating
migraine may be assessed using a randomized, double blind,
placebo-controlled, parallel group, clinical trial. The primary
objective of the study is to evaluate the safety and efficacy of a
test compound vs placebo in the treatment of recurrent episodes of
migraine based on change from the baseline phase to the
double-blind phase in the monthly (28 days) migraine episode rate.
The secondary objectives are to evaluate the effect of treatment
with a test compound versus placebo in migraine patients on
percentage of subjects responding to treatment (50% or more
reduction in monthly migraine episode rate) and change from the
baseline phase to the double-blind phase in migraine days per
month, average migraine duration, rescue medication use, average
severity of migraine headache, average severity of migraine
associated symptoms (nausea, vomiting, photophobia, phonophobia),
to provide safety and efficacy data for the comparison a dose of a
test compound in the treatment of migraine, and to evaluate the
effect of treatment with a dose of a test compound versus placebo
in migraine patients on migraine-specific measures of
health-related quality of life (HRQL) and SF-36 quality-of-life
measures, as well as the correlation between HRQL and migraine
frequency.
[0589] The clinical trial is a randomized, double blind, placebo
controlled, parallel-group, multicenter study to evaluate the
efficacy and safety of one or more doses of a test compound versus
placebo in migraine prophylaxis. Patients are randomized into
treatment groups. The patients must have been diagnosed with
migraine for at least twelve months, with or without aura, as
defined by the International Headache Society (HIS). The IHS
diagnostic criteria differ from the definition of a migraine period
utilized in this study for evaluation of efficacy. For the purposes
of this study a migraine period is defined as the twenty-four hour
period starting with the onset of painful migraine symptoms, or
aura with successful abortive/rescue treatment. Any recurrence
during the twenty-four hour period is considered part of the
initial episode. If the migraine pain persists beyond the
twenty-four hour period, for the purposes of this study, this is
considered a new episode.
[0590] There are four phases in the clinical trial: Baseline, Core
Double-Blind, Blinded Extension, and Taper/Exit. The Baseline Phase
lasts up to 42 days and includes two periods: Washout and
Prospective Baseline. At Baseline Visit 1 (screening), patients are
evaluated to ensure that they meet inclusion/exclusion criteria. In
addition, a three-month retrospective headache history is recorded.
During each of the three months prior to Visit 1, patients should
have had no more than 8 migraines and no more than 15 total
headache days (migraine plus other headache types). Eligible
patients then undergo other study procedures and are given a
headache/rescue medication record. Patients maintain this record
from Visit I throughout their participation in the clinical trial,
documenting the occurrence of any headaches, or auras, as well as
the duration, severity, and symptomatology of any migraine attacks.
Patients also record the use of any abortive/rescue medication
taken for the relief of migraine pain and associated symptoms, or
during an aura to prevent migraine pain or relieve symptoms. In
addition, for each migraine attack, patients answer the questions
on the headache record regarding work loss and productivity. If at
the start of the trial, eligible patients are on any prophylactic
medication to treat their migraines, they enter a Washout Period of
up to 14 days to taper from these medications. This washout is
concluded by the time the patient enters the Prospective Baseline
Period, 28 days prior to Visit 2 (randomization).
[0591] At Baseline Visit 2 (Day 1), headache/rescue medication
record information is reviewed. To be eligible for randomization
into the trial a patient must have had 3 to 12 migraine episodes
but no greater than 15 (migraine and non-migraine), headache days
during the 28 days prior to Visit 2.
[0592] In the Core Double-Blind Phase, patients who complete the
Baseline Phase and meet the entry criteria (including Prospective
Baseline Period migraine/headache rate) are randomized into
treatment groups representing one or more doses of test compound or
placebo. The Core Double-Blind Phase has two periods: Titration and
Maintenance.
[0593] The Titration Period immediately follows the Baseline Phase
and extends for eight weeks (56 days). During this period, patients
randomized to test compound are started at an initial dose and the
daily dose is increased weekly until the assigned dose is achieved
(or maximum tolerated dose, whichever is less). From the third week
of Titration until the end of the Maintenance Period, a maximum of
two dose level reductions are permitted for unacceptable
tolerability problems. If a patient is still in the Titration
Period, after a dose reduction, rechallenge is attempted to
approach the patient's assigned dose, and, if unsuccessful, the
dose is reduced again to the original reduced dose. Patients who
have already had their study medication dose decreased by two
levels, and are still experiencing unacceptable tolerability
problems, which warrant additional dose reductions, exit the study,
or enter the Open Label Extension Phase, where their dose is
further adjusted. Clinic visits occur on, for example, Day 29
(Visit 3) and Day 57 (Visit 4/End of Titration).
[0594] During the 18-week Maintenance Period, patients remain on
the dose of test compound reached at the end of the Titration
Period (the assigned dose or the maximum tolerated dose). If a
patient experiences unacceptable tolerability problems, the dose is
reduced, but only to the point that there are no more than two dose
reductions for the entire Core Phase (Titration plus Maintenance).
No rechallenge is permitted during the Maintenance Period, so a
patient continues on the reduced dose for the remainder of the
period. Patients who have already had their study medication dose
decreased by two levels, and are still experiencing unacceptable
tolerability problems, which would warrant additional dose
reductions, exit the study. Clinic visits occur, for example, on
Day 83 (Visit 5), Day 113 (Visit 6), Day 141 (Visit 7) and Day 183
(Visit 8/Core Double-Blind Final Visit or Early Withdrawal).
[0595] Patients are considered to have completed the Core
Double-Blind Phase if they complete all 26 weeks of the Phase (8
weeks of Titration and 18 weeks of Maintenance) without prematurely
discontinuing study medication. Only patients who complete all 26
weeks of the Core Phase have the option of entering the Blinded
Extension Phase.
[0596] During the Blinded Extension Phase, patients remain on test
compound at the same dose they achieve during the Core Phase for
six months, or until they withdraw. During this phase, patients are
not permitted to adjust the dose of test compound. Patients are
seen quarterly during this phase (Visits 10 and 11/Blinded
Extension Final Visit). Patients are considered to have completed
the Blinded Extension Phase if they complete all six months of the
Phase without prematurely discontinuing the test compound.
[0597] In the Taper/Exit Phase, patients exiting the study are
tapered from study medication. If a patient exits the study during
the Core Double-Blind Phase (Titration or Maintenance Period), he
or she is tapered from study medication in a blinded fashion. The
length of the taper is as long as seven weeks, but varied according
to the dose the patient achieves. Patients who exit the study
during the Blinded Extension Phase are tapered from their
medication following the recommended taper schedule.
[0598] Physical examinations (including height) and neurologic
examinations are performed at the beginning and end of the study. A
baseline electrocardiogram is performed at the beginning of the
study. Vital signs and weight are recorded at each clinic visit.
Adverse events are recorded. Quality of Life assessments are
performed at intervals, for example, Visits 2 (Day 1), 4 (Day
57/Exit from Titration), 6 (Day 113) and 8 (Day 183/Core
Double-Blind Final Visit/Early Withdrawal). Health Care Resource
Use information is recorded at intervals, for example, Visits 3
through 8. The occurrence of any headaches or auras, severity and
symptomatology of any migraine headaches, and the use of rescue
medication is transcribed from a patient's headache record to their
case record form at each visit.
[0599] Efficacy evaluations are based on information recorded on
the subject's headache/rescue medication record and Health-Related
Quality of Life assessments. On the headache/rescue medication
record the patients documented the following throughout his/her
study participation: occurrence and duration of headaches (and
auras if no headache pain develops), severity of migraine pain and
associated symptoms, as well as the use of medication taken to
relieve migraine pain or symptoms (or taken during an aura to
relieve symptoms or prevent migraine pain). Health-Related Quality
of Life (HRQL) assessments are completed at specified intervals
throughout the study. The Migraine-Specific Quality of Life
questionnaire (MSQ), and the Medical Outcomes Study Short Form-36
(SF-36) can be used to assess HRQL.
[0600] The primary efficacy criterion is the reduction in migraine
episodes per month (28 days) during the Core Double-Blind Phase
compared to the 28 day Prospective Baseline Period. Secondary
efficacy criteria include the percentage of patients responding to
treatment (50% or more reduction in the monthly (28 day) migraine
episode rate) and reduction from the Prospective Baseline Period to
the Core Double-Blind Phase in migraine days per month, monthly
rate of all types of headaches, average migraine duration, rescue
medication use, average severity of migraine headache, and average
severity of migraine-associated symptoms (nausea, vomiting,
photophobia, phonophobia). Also included in the secondary efficacy
criteria is the effect of treatment with test compound versus
placebo on migraine-specific measures of health-related quality of
life (HRQL) and SF-36 quality-of-life measures, as well as the
correlation between HRQL and migraine frequency. The Medical
Outcomes Study Short Form-36 (SF-36) is the most frequently used
generic measure of HRQL in migraine patients and has been used in
studies of migraine. The SF-36 is a 36-item questionnaire measuring
eight domains. The SF-36 has been shown to be reliable and valid in
a wide variety of patient populations as well as for migraine
patients. The migraine specific quality of life questionnaire (MSQ)
can also be administered. The MSQ is a disease-specific instrument
developed to assess quality of life relating to migraine. The MSQ
has been used in published clinical trials of migraine therapy and
has demonstrated evidence of reliability, validity, and
responsiveness.
Description 19
Animal Model for Assessing Therapeutic Efficacy of Acamprosate
Prodrugs for Treating Schizophrenia
Morris Water Maze
[0601] The Morris Water Maze (MWM) is used as a well-validated
hippocampus dependent test of visual-spatial memory. The MWM tests
the ability of an animal to locate a hidden platform submerged
under water by using extra-maze cues from the test environment.
Rats are trained in a pool 1.8 m in diameter and 0.6 .mu.m high,
containing water at about 26.degree. C. A 10 cm square transparent
platform is hidden in a constant position 1 cm below the water
level in the pool. Only distal visuo-spatial cues are available to
the rats for location of the submerged platform. The rats are given
trials to find the hidden platform. The escape latency, i.e., the
time required by the rats to find and climb onto the platform, is
recorded for up to 120 s. Each rat is allowed to remain on the
platform for 30 s, after which it is removed to its home cage. If
the rat did not find the platform within 120 s, it is manually
placed on the platform and returned to its home cage after 30
s.
[0602] Male Sprague-Dawley rats weighing 150-200 g are used. Ten
days before the beginning of the experiments, the rats are handled
once daily to reduce experimental stress. Acamprosate prodrug or
control is administered to the rats for three consecutive days
before behavioral testing. On each day of behavioral testing the
rats are injected with either haloperidol or saline 30 min before
behavioral assessment.
PCP-Induced Hyperactivity Model
[0603] Male C57BI/6J mice are used. Mice are received at 6-weeks of
age. Upon receipt, mice are assigned unique identification numbers
(tail marked) and are group housed with 4 mice/cage in OPTI mouse
ventilated cages. All animals remain housed in groups of four
during the study. All mice are acclimated to the colony room for at
least two weeks prior to testing and are subsequently tested at an
average age of 8 weeks of age. During the period of acclimation,
mice and rats are examined on a regular basis, handled, and weighed
to assure adequate health and suitability.
[0604] Test compounds are prepared and administered according to
the following procedures. An acamprosate prodrug is dissolved in
sterile injectable water and administered i.p. at a dose volume of
10 mL/kg at 60 min prior to PCP injection. The amount of
acamprosate prodrug administered can range, for example, from 0.01
mg/kg to 100 mg/kg. As a positive control, clozapine (1 mg/kg) is
dissolved in 10% DMSO and administered i.p. at a dose volume of 10
mL/kg at 30 min prior to PCP injection. PCP (5 mg/kg) is dissolved
in sterile injectable water and administered i.p. at a dose volume
of 10 mL/kg.
[0605] The Open Filed (OF) test is used to assess both anxiety and
locomotor behavior. The open field chambers are Plexiglas square
chambers (27.3.times.27.3.times.20.3 cm) surrounded by infrared
photobeams (16.times.16.times.16) to measure horizontal and
vertical activity. The analysis is configured to divide the open
field into a center and periphery zone. Distance traveled is
measured from horizontal beam breaks as a mouse moves, and rearing
activity is measured from vertical beam breaks.
[0606] Mice are acclimated to the activity experimental room for at
least 1 h to prior to testing. Eight animals are tested in each
run. Mice are injected with water or acamprosate prodrug, placed in
holding cages for 30 min, and then in the OF chamber for 30 min,
removed from the OF chamber and injected with either water or PCP
and returned to the OF chambers for a 60-minute session. A
different group of mice are injected with either 10% DMSO or
clozapine and placed in the OF chamber for 30 min, removed from the
OF chamber and injected with PCP (5 mg/kg), and returned to the OF
chambers for a 60-minute session.
[0607] Data is analyzed by analysis of variance (ANOVA) followed by
post-hoc comparisons with Fisher Tests when appropriate. Baseline
activity is measured during the first 30 min of the test prior to
PCP injection. PCP-induced activity is measured during the 60 min
following PCP injection. Statistical outliers that fall above or
below 2 standard deviations from the mean are removed from the
final analysis. An effect is considered significant if p<0.05
.
Auditory Startle and Prepulse Inhibition of Startle (PPI)
[0608] Young, adult male C57B1/6J mice are used in this study. Mice
are received at 6-weeks of age. Upon receipt, mice are assigned
unique identification numbers (tail marked) and are group housed in
standard mouse cages. For testing, animals are randomly assigned
across treatment groups and balanced by PPI chamber.
[0609] Acoustic startle measures an unconditioned reflex response
to external auditory stimulation. PPI consisting of an inhibited
startle response (reduction in amplitude) to an auditory
stimulation following the presentation of a weak auditory stimulus
or prepulse, has been used as a tool for the assessment of
deficiencies in sensory-motor gating, such as those seen in
schizophrenia. Mice are placed in the PPI chamber (Med Associates)
for a 5 min session of white noise (70 dB) habituation. A test
session begins immediately after the 5 min acclimation period. The
session starts with a habituation block of 6 presentations of the
startle stimulus alone, followed by 10 PPI blocks of 6 different
types of trials. Trial types are: null (no stimuli), startle (120
dB), startle plus prepulse (4, 8 and 12 dB over background noise
i.e., 74, 78 or 82 dB) and prepulse alone (82 dB). Trial types are
presented at random within each block. Each trial begins with a 50
ms null period during which baseline movements are recorded. There
is a subsequent 20 ms period during which prepulse stimuli are
presented and responses to the prepulse measured. Following a 100
ms pause, the startle stimuli are presented for 40 ms and responses
are recorded for 100 ms from startle onset. Responses are sampled
every ms. The inter-trial interval is variable with an average of
15 s (range from 10 to 20 s). In startle alone trials the basic
auditory startle is measured and in prepulse plus startle trials
the amount of inhibition of the normal startle is determined and
expressed as a percentage of the basic startle response (from
startle alone trials), excluding the startle response of the first
habituation block.
[0610] For the normal mouse-PPI portion of the study, C57BL/6J mice
are treated with vehicle, haloperidol or acamprosate prodrug and
placed back in their holding cages. Thirty min following
administration of vehicle or haloperidol and 60 min following
injection of vehicle or acamprosate prodrug, normal mouse-PPI
testing commences.
[0611] For the PCP-PPI portion of the study, C57BL/6J mice are
treated with vehicle, clozapine, or acamprosate prodrug and
returned to their holding cages. Thirty min later, all treatment
groups are injected with vehicle or PCP. Thirty min following
vehicle or PCP injection, PPI testing commences.
Description 20
Animal Model for Assessing Therapeutic Efficacy of Acamprosate
Prodrugs for Treating Anxiety
[0612] The elevated plux-maze test can be used to assess the
effects of test compounds on anxiety. A plus-maze is consists of
two open arms (50.times.10 cm) and two closed arms
(50.times.10.times.40 cm). The arms extend from a central platform
(10.times.10 cm) and are raised 50 cm. Each mouse is placed at the
center of the maze facing a closed arm and is allowed to explore
the maze for 5 min. The time spent in the open arms and the time
spent in the closed arms is monitored, and the percent of time
spent in the open arms determined. Increased time spent in the open
arms indicates an anxiolytic effect for the test condition. A test
that measures spontaneous locomotor activity such as measurement in
an activity cage can be used to determine whether the test compound
also affects locomotor activity. It is desirable that a compound
exhibiting an anxiolytic effect not decrease locomotor
activity.
Description 21
Animal Models of Depression
Forced Swim Test in Rats
[0613] Male Wistar rats weighting 230-270 g are acclimated to the
colony room for a minimum of 1 week, handled daily for at least 4
days and habituated to saline injections for 2 days before the
experiments.
[0614] Two glass cylinders (20 cm di.times.40 cm height) are
separated by black opaque partitions and filled with water at about
24.degree. C. to a depth of 30 cm. At this depth a rat cannot stand
on the cylinder bottom. The water level is 10 cm from the top.
Water is changed before each animal is placed into the water tank.
An experimental session consists of two trials. During the
conditioning trial, rats are gently placed into the cylinders for
15 min. After the trial, rats are dried and placed into a warm cage
with the paper towels for 10-15 min before being returned to their
home cages. Twenty-four hours later, for the test trial, animals
are placed again into the cylinders for a 5-min test session. Tests
are video taped for subsequent quantitative behavioral analysis.
The frequency and/or total duration are calculated for each of the
following categories: passive/immobile behavior (floating is scored
when an animal remains in the water with all four limbs motionless,
except for occasional alternate movements of paws and tail
necessary to prevent sinking and to keep head/nose above the
water); active/mobile behaviors (swimming characterized by rigorous
movements with all four legs; paddling characterized by floating
with rhythmical simultaneous kicks and occasional pushes off the
wall to give speed and direction to the drift), including
escape-oriented behaviors (climbing characterized by intense
movements with all four limbs, with the two forepaws breaking the
surface of the water and being directed against the walls of the
cylinder; diving characterized by movements towards the bottom of
the cylinder with the head of the rat below its hind limbs), and
self-directed behaviors (headshakes, vigorous headshakes to get
water off the snout and eyes; wiping, rubbing water away from the
snout). In addition, at the end of each test trial, fecal boli are
counted. A test compound, control, or positive control (e.g.,
imipramine) is administered prior to the test.
Tail Suspension Test in Mice
[0615] Mice are housed in standard laboratory cages and acclimated.
Mice are moved from the housing room to the testing area in their
home cages and allowed to adapt to the new environment for at least
1 h before testing. Immobility is induced by tail suspension. Mice
are hung individually on a paper adhesive tape, 65 cm above a
tabletop. Tape is placed approximately 1 cm from the tip of the
tail. Animals are allowed to hang for 6 min and the duration of
immobility is recorded. Mice are considered immobile only when
hanging passively and completely motionless. Mice from these
experiments are used one week later in locomotor activity studies.
A test compound, control, or positive control (e.g., imipramine) is
administered prior to the test.
Locomotor Activity
[0616] The spontaneous locomotor activity of mice is measured in
photoresistor actometers (circular cages, 25 cm in dia, 15 cm high,
two light sources, two photoresistors), in which the animals are
placed individually 1 h after administration of a test compound.
The number of crossings of light beams is measured during the first
30 min of the experimental session. The first measurement is
performed 6 min after placing an animal into the actometer.
Description 22
Animal Model for Assessing Therapeutic Efficacy of Acamprosate
Prodrugs for Treating Tardive Dyskinesia
[0617] Vacuous chewing movements (VCM) are a rodent model of TD. In
this model, animals are treated chronically with antipsychotics and
their vacuous chewing motions are assessed by observation. The
model has been shown to be sensitive to differential effects of
typical and atypical antipsychotics and potential anti-dyskinetic
agents.
[0618] Rats are housed in a controlled environment and allowed to
acclimatize prior to testing. In order to limit neuroleptic-induced
weight gain, food consumption is restricted to 15 g per animal per
day. Rats are weighed biweekly throughout the study.
[0619] For two weeks prior to administration of test compound,
animals are handled daily and habituated to the animal colony and
the procedures related to drug administration and video recording.
Subsequently (week 0), rats undergo a behavior video recording
session following which they are randomized to a haloperidol
treatment and a control group. The rats in the treatment group
receive an intramuscular injection in the thigh muscles with
haloperidol decanoate. The control rats are similarly injected with
an equal volume of phosphate buffered saline (PBS). The haloperidol
decanoate and saline injections are repeated every four weeks, for
20 weeks. Additional behavior video recording sessions are
performed at weeks 12, 20 and 24 (i.e., 4 weeks after the last
(fifth) injection). During the injection procedures, rats are
handheld with minimal restraint.
[0620] On the basis of the results of the behavior assessment
performed 24 weeks after the first haloperidol injection (i.e.,
baseline day), the haloperidol-treated rats are assigned to 10
subject-each treatment groups having an equal mean frequency of
observed VCM episodes. One week later (i.e., test day), the groups
are randomized to receive either 0.5 mL PBS (vehicle) or
acamprosate prodrug in 0.5 mL PBS. Rats undergo a 30-150 min video
recorded behavior assessment session following administration. Two
weeks after the test day (i.e., post-test day), the video recorded
behavior assessment session is repeated to investigate longer-term
effects of the experimental treatments.
[0621] The videotapes are scored. A VCM episode is defined as a
bout of vertical deflections of the lower jaw, which may be
accompanied by contractions of the jaw musculature.
Description 23
Animal Model for Assessing Therapeutic Efficacy of Acamprosate
Prodrugs for Treating Spasticity
[0622] The mutant spastic mouse is a homozygous mouse that carries
an autosomal recessive trait of genetic spasticity characterized by
a deficit of glycine receptors throughout the central nervous
system. The mouse is normal at birth and subsequently develops a
coarse tremor, abnormal gait, skeletal muscle rigidity, and
abnormal righting reflexes at two to three weeks of age. Assessment
of spasticity in the mutant spastic mouse can be performed using
electrophysiological measurements or by measuring the righting
reflex (any righting reflex over one second is considered
abnormal), tremor (holding mice by their tails and subjectively
rating tremor), and flexibility.
[0623] Models of acute spasticity including the acute decerebrate
rat, the acute or chronic spinally transected rat, and the
chronically spinal cord-lesioned rat. The acute models, although
valuable in elucidating the mechanisms involved in the development
of spasticity, have come under criticism due to the fact that they
are acute. The animals usually die or have total recovery from
spasticity. The spasticity develops immediately upon intervention,
unlike the spasticity that evolves in the human condition of
spasticity, which most often initially manifests itself as a
flaccid paralysis. Only after weeks and months does spasticity
develop in humans. Some of the more chronic-lesioned or spinally
transected models of spasticity do postoperatively show flaccid
paralysis. At approximately four weeks post-lesion/transection, the
flaccidity changes to spasticity of variable severity. Although all
of these models have their own particular disadvantages and lack of
true representation of the human spastic condition, they are shown
useful in developing treatments for spasticity in humans. Many of
these models have also made use of different species, such as cats,
dogs, and primates. Baclofen, diazepam, and tizanidine, effective
antispastic agents in humans, are effective on different parameters
of electrophysiologic assessment of muscle tone in these
models.
[0624] The Irwin Test is used to detect physiological, behavioral,
and toxic effects of a test substance, and indicates a range of
dosages that can be used for later experiments. Typically, rats
(three per group) are administered the test substance and are then
observed in comparison with a control group given vehicle.
Behavioral modifications, symptoms of neurotoxicity, pupil
diameter, and rectal temperature are recorded according to a
standardized observation grid derived from that of Irwin. The grid
contains the following items: mortality, sedation, excitation,
aggressiveness, Straub tail; writhes, convulsions, tremor,
exophthalmos, salivation, lacrimation, piloerection, defecation,
fear, traction, reactivity to touch, loss of righting reflexes,
sleep, motor incoordination, muscle tone, stereotypes,
head-weaving, catalepsy, grasping, ptosis, respiration, corneal
reflex, analgesia, abnormal gait, forepaw treading, loss of
balance, head twitches, rectal temperature, and pupil diameter.
Observations are performed at 15, 30, 60, 120, and 180 minutes
following administration of a test compound, and also 24 hours
later.
[0625] In the Rotarod Test rats or mice are placed on a rod
rotating at a speed of eight turns per minute. The number of
animals that drop from the rod before three minutes is counted and
the drop-off times are recorded (maximum: 180 sec). Diazepam, a
benzodiazepine, can be administered at 8 mg/kg, i.p., as a
reference substance.
Description 24
Animal Model for Assessing Therapeutic Efficacy of Acamprosate
Prodrugs for Treating Multiple Sclerosis
[0626] Experiments are conducted on female C57BL/6 mice aged 4-6
weeks weighing 17-20 g. Experimental autoimmune encephalomyelitis
(EAE) is actively induced using .gtoreq.95% pure synthetic myelin
oligodendrocyte glycoprotein peptide 35-55 (MOG35-55,
MEVGWYRSPFSRVVHLYRNGK). Each mouse is anesthetized and receives 200
.mu.g of MOG peptide and 15 .mu.g of Saponin extract from Quilija
bark emulsified in 100 .mu.L of phosphate-buffered saline. A 25
.mu.L volume is injected subcutaneously over four flank areas. Mice
are also intraperitoneally injected with 200 ng of pertussis toxin
in 200 .mu.L of PBS. A second, identical injection of pertussis
toxin is given after 48 h.
[0627] An acamprosate prodrug is administered at varying doses.
Control animals receive 25 .mu.L of DMSO. Daily treatment extends
from day 26 to day 36 post-immunization. Clinical scores are
obtained daily from day 0 post-immunization until day 60. Clinical
signs are scored using the following protocol: 0, no detectable
signs; 0.5, distal tail limpness, hunched appearance and quiet
demeanor; 1, completely limp tail; 1.5, limp tail and hindlimb
weakness (unsteady gait and poor grip with hindlimbs); 2,
unitlateral partial hindlimb paralysis; 2.5, bilateral hindlimb
paralysis; 3, complete bilateral hindlimb paralysis; 3.5, complete
hindlimb paralysis and unilateral forelimb paralysis; 4, total
paralysis of hindlimbs and forelimbs.
[0628] Inflammation and demyelination are assessed by histology on
sections from the CNS of EAE mice. Mice are sacrificed after 30 or
60 days and whole spinal cords are removed and placed in 0.32 M
sucrose solution at 4.degree. C. overnight. Tissues are prepared
and sectioned. Luxol fast blue stain is used to observe areas of
demyelination. Haematoxylin and eosin staining is used to highlight
areas of inflammation by darkly staining the nuclei of mononuclear
cells. Immune cells stained with H&E are counted in a blinded
manner under a light microscope. Sections are separated into gray
and white matter and each sector is counted manually before being
combined to give a total for the section. T cells are
immunolabelled with anti-CD3+ monoclonal antibody. After washing,
sections are incubated with goat anti-rat HRP secondary antibody.
Sections are then washed and counterstained with methyl green.
Spenocytes isolated from mice at 30 and 60 days post-immunization
are treated with lysis buffer to remove red blood cells. Cells are
then resuspended in PBS and counted. Cells at a density of about
3.times.106 cells/mL are incubated overnight with 20 .mu.g/mL of
MOG.sub.35-55 peptide. Supernatants from stimulated cells are
assayed for IFN-.gamma. protein levels using an appropriate mouse
IFN-y immunoassay system.
Description 25
Animal Models of Pain
[0629] Inflammatory Pain--Formalin test
[0630] A formalin assessment test is used. Fifty .mu.L of a 5%
formalin solution is injected subcutaneously into the dorsal aspect
of the right hind paw and the rats are then individually placed
into clear observation cages. Rats are observed for a continuous
period of 60 min or for periods of time corresponding to phase I
(from 0 to 10 min following formalin injection) and phase II (from
30 to 50 min following formalin injection) of the formalin test
(Abbott et al., Pain 1995, 60, 91-102). The number of flinching
behaviors of the injected paw is recorded using a sampling
technique in which each animal is observed for one 60-sec period
during each 5-min interval. Test compound is administered 30 min or
other appropriate interval prior to formalin injection.
Inflammatory Pain--Carrageenan-Induced Acute Thermal Hyperalgesia
and Edema
[0631] Paw edema and acute thermal hyperalgesia are induced by
injecting 100 .mu.L of a 1% solution of .lamda.-carrageenan in
physiological saline into the plantar surface of the right hind
paw. Thermal hyperalgesia is determined 2 h following carrageenan
injection, using a thermal paw stimulator. Rats are placed into
plastic cubicles mounted on a glass surface maintained at
30.degree. C. and a thermal stimulus in the form of radiant heat
emitted form a focused projection bulb is then applied to the
plantar surface of each hind paw. The stimulus current is
maintained at 4.50.+-.0.05 amp, and the maximum time of exposure is
set at 20.48 sec to limit possible tissue damage. The elapsed time
until a brisk withdrawal of the hind paw from the thermal stimulus
is recorded automatically using photodiode motion sensors. The
right and left hind paw of each rat is tested in three sequential
trials at about 5-min intervals. Carrageenan-induced thermal
hyperalgesia of paw withdrawal latency (PWL.sub.thermal) is
calculated as the mean of the two shortest latencies. Test compound
is administered 30 min before assessment of thermal
hyperalgesia.
[0632] The volume of paw edema is measured using water displacement
with a plethysmometer 2 h following carrageenan injection by
submerging the paw up to the ankle hairline (approx. 1.5 cm). The
displacement of the volume is measured by a transducer and
recorded. Test compound is administered at an appropriate time
following carrageenan injection, such as for example, 30 min or 90
min.
Visceral Pain
[0633] Thirty min following administration of test compound, mice
receive an injection of 0.6% acetic acid in sterile water (10
mL/kg, i.p.). Mice are then placed in table-top Plexiglass
observation cylinders (60 cm high.times.40 cm diameter) and the
number of constrictions/writhes (a wave of mild constriction and
elongation passing caudally along the abdominal wall, accompanied
by a slight twisting of the trunk and followed by bilateral
extension of the hind limbs) is recorded during the 5-20 min
following acetic acid injection for a continuous observation period
of 15 min.
Neuropathic Pain--Spinal Nerve Ligation
[0634] Rats receive unilateral ligation of the lumbar 5 (L5) and
lumbar 6 (L6) spinal nerves. The left L5 and L6 spinal nerves of
the rat are isolated adjacent to the vertebral column and tightly
ligated with a 5-0 silk suture distal to the dorsal root ganglia,
and care is taken to avoid injury of the lumbar 4 (L4) spinal
nerve. Control rats undergo the same procedure but without nerve
ligation. All animals are allowed to recover for at least 1 week
and not more than 3 weeks prior to assessment of mechanical
allodynia. Mechanical allodynia is measure using calibrated von
Frey filaments. Rats are placed into inverted plastic containers
(20.times.12.5.times.20 cm) on top of a suspended wire mesh grid
and acclimated to the test chamber for 20 min. The von Frey
filaments are presented perpendicularly to the plantar surface of
the selected hind paw, and then held in this position for
approximately 8 s with enough force to cause a slight bend in the
filament. Positive responses include an abrupt withdrawal of the
hind paw from the stimulus or flinching behavior immediately
following removal of the stimulus. A 50% paw withdrawal threshold
(PWT) is determined. Rats with a PWT.ltoreq.5.0 g are considered
allodynic and utilized to test the analgesic activity of a test
compound. The test compound can be administered 30 min prior to the
assessment of mechanical allodynia.
Neuropathic Pain--Chronic Constriction Injury of the Sciatic
Nerve
[0635] A model of chronic constriction injury of the sciatic
nerve-induced neuropathic pain is used. The right common sciatic
nerve is isolated at mid-thigh level and loosely ligated by four
chromic gut (4-0) ties separated by an interval of 1 mm. Control
rats undergo the same procedure but without sciatic nerve
constriction. All animals are allowed to recover for at least 2
weeks and for no more than 5 weeks prior to testing of mechanical
allodynia. Allodynic PWT is assessed in the animals as described
for animals with spinal nerve ligation. Only rats with a
PWT.ltoreq.5.0 g are considered allodynic and utilized to evaluate
the analgesic activity of a test compound. Test compound is
administered 30 min or other appropriate time prior to the
assessment of mechanical allodynia.
Neuropathic Pain--Vincristine-induced Mechanical Allodynia
[0636] A model of chemotherapy-induced neuropathic pain is produced
by continuous intravenous vincristine infusion (Nozaki-Taguchi et
al., Pain 2001, 93, 69-76). Anesthetized rats undergo a surgical
procedure in which the jugular vein is catheterized and a
vincristine-primed pump is implanted subcutaneously. Fourteen days
of intravenous infusion of vincristine (30 .mu.g/kg/day) results in
systemic neuropathic pain of the animal. Control animals undergo
the same surgical procedure, with physiological saline infusion.
PWT of the left paw is assessed in the animals 14 days
post-implantation as described for the spinal nerve ligation model.
Test compound is administered 30 min prior to the test for
mechanical allodynia in rats with PWT.ltoreq.5.00 g before
treatment.
Post-Operative Pain
[0637] A model of post-operative pain is performed in rats. The
plantar aspect of the left hind paw is exposed through a hole in a
sterile plastic drape, and a 1-cm longitudinal incision is made
through the skin and fascia, starting 0.5 cm from the proximal edge
of the heel and extending towards the toes. The plantaris muscle is
elevated and incised longitudinally leaving the muscle origin and
insertion points intact. After hemostasis by application of gently
pressure, the skin is apposed with two mattress sutures using 5-0
nylon. Animals are then allowed to recover for 2 h following
surgery, at which time mechanical allodynia and thermal
hyperalgesia are assessed.
[0638] Effects of test compound on mechanical allodynia are
assessed 30 min following administration, with PWT being examined
in these animals for both the injured and non-injured paw as
described for the spinal nerve ligation model with the von Frey
filament systematically pointing towards the medial side of the
incision. In a separate experiment, the effects of test compound on
thermal hyperalgesia are assessed 30 min following administration
of test compound, with PWL.sub.thermal being determined as
described for the carrageen-induced thermal hyperalgesia model with
the thermal stimulus applied to the center of the incision of the
paw planter aspect.
Description 26
Animal Model for Assessing Therapeutic Efficacy of Acamprosate
Prodrugs for Treating Binge Eating
[0639] Thirty 2-month old male Sprague Dawley rats are individually
housed in a temperature- and humidity-controlled vivarium under a
12:12 light:dark cycle. Three days after being introduced into the
vivarium, rats are given overnight access to a bowl of vegetable
shortening. The rats are then divided into three groups of ten
matched for two-day average chow intake, overnight shortening
intake, and body weight.
[0640] The groups and different test phases are designed to test
the effects of acamprosate prodrug under different shortening
access conditions. In phase 1, rats maintained on a feeding
protocol that promotes infrequent, large binges (B group) are
compared to rats maintained on feeding protocols that promote no
binges (FM and C groups). In phase 2, rats maintained for an
extended period of time on the infrequent, large binge protocol (B
group) are compared to rats that have just started the same binge
protocol (FM and C groups). In phase 3, rats maintained on the
feeding protocol that promotes infrequent, large binges (B group)
are compared to rats on a feeding protocol that promotes more
frequent, smaller binges (FM and C groups).
[0641] The three groups are maintained as follows: Binge (B): The
(B) rats have continuous access to chow and water. In addition,
they are given 2-h access to a separate bowl of vegetable
shortening every Monday, Wednesday, and Friday (MWF), during the 2
h prior to no light. During the 2-h shortening access period, the
chow and water remain available. This protocol results in
infrequent, large episodes of binge-type eating in male rats. This
protocol models the intermittent excessive eating behavior that
characterizes binge eating. The B rats are maintained on this
protocol throughout all phases of the study. Fat-Matched (FM): The
rats in group FM are given the same proportions of chow and
shortening that the Binge (B) groups consume except that the
shortening is mixed into the chow, which is provided continuously.
The proportions of chow and shortening consumed by the Binge group
each week are determined, and the FM group is provided with a
fat-matched chow mixed to that proportion the following week. The
FM group has free access to the FM chow and water. The FM group is
included to control for possible neural or behavioral effects of
dietary fat. The FM group is maintained on the FM chow throughout
all phases of the study. During phase 1, the FM group only has
access to the FM chow. During phase 2, the FM group has access to a
separate bowl of vegetable shortening for 2-h on MWF each week, in
addition to the continuously available FM chow. During phase 3, the
FM group has 2-h access to the vegetable shortening every day, in
addition to the continuously available FM chow. This daily protocol
results in more frequent, smaller episodes of binge-type eating.
Chow/change (C): The rats in group C have continuous access to the
regular chow and water through all phases of the study. During the
first phase, the C group only has access to the regular chow diet.
During the second phase, the C group has access to a separate bowl
of vegetable shortening for 2-h on MWF each week in addition to the
continuously available regular chow. During the third phase, the C
group has 2-h access to the vegetable shortening every day in
addition to the continuously available regular chow.
[0642] The effects of acamprosate prodrugs effects are determined
during each of the three phases of the study. In phase 1, the
effects of acamprosate prodrug are determined on binge-type
consumption of vegetable shortening and on consumption of the
regular and FM chow diets. Rats are on their respective diets for
about 6 weeks prior to the initiation of acamprosate prodrug
testing. In phase 2, the effects of acamprosate prodrug are
assessed in rats that are bingeing for a relatively long (B group:
three months) or short (FM and C groups: 1 day) period of time (all
groups have MWF 2-h access to shortening in addition to their
assigned regular or FM chow). In phase 3, the effects of
acamprosate prodrug are assessed under conditions of infrequent (B:
2-h MWF) and more frequent (FM and C groups: 2-h daily) shortening
access. The FM and C rats are on the daily shortening access
schedule for ten days before the first acamprosate prodrug
administration in phase 3. Acamprosate prodrug is not tested in
rats with continuous access to a bowl of shortening due to the low
2-h intakes that are generated on that protocol under
non-food-deprived conditions. A dose and regimen of acamprosate
prodrug is administered as appropriate for the objectives of the
study.
[0643] Acamprosate prodrug is administered at an appropriate time
prior to the shortening access period. Chow is removed during the
30-min pretreatment period. Shortening and/or chow are weighted and
placed into the cage at the beginning of the test period, e.g.,
2-h, and then re-weighted at the end of the test period. The data
is analyzed using appropriate statistical methods.
[0644] Finally, it should be noted that there are alternative ways
of implementing the embodiments disclosed herein. Accordingly, the
present embodiments are to be considered as illustrative and not
restrictive, and the claims are not to be limited to the details
given herein, but may be modified within the scope and equivalents
thereof.
* * * * *