U.S. patent application number 09/819693 was filed with the patent office on 2001-11-22 for aminopyridines and methods of using thereof.
This patent application is currently assigned to CoCensys, Inc.. Invention is credited to Hogenkamp, Derk J..
Application Number | 20010044428 09/819693 |
Document ID | / |
Family ID | 22713650 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010044428 |
Kind Code |
A1 |
Hogenkamp, Derk J. |
November 22, 2001 |
Aminopyridines and methods of using thereof
Abstract
This invention relates to aminopyridines of Formula I: 1 or a
pharmaceutically acceptable salt, prodrug or solvate thereof,
wherein R.sub.1-R.sub.8, X and m are set in the specification. The
invention is also directed to the use of compounds of Formula I for
the treatment of neuronal damage following global and focal
ischemia, for the treatment or prevention of neurodegenerative
conditions such as amyotrophic lateral sclerosis (ALS), and for the
treatment, prevention or amelioration of both acute or chronic
pain, as antitinnitus agents, as anticonvulsants, and as antimanic
depressants, as local anesthetics, as antiarrhythmics and for the
treatment or prevention of diabetic neuropathy.
Inventors: |
Hogenkamp, Derk J.;
(Carlsbad, CA) |
Correspondence
Address: |
STERNE, KESSLER, GOLDSTEIN & FOX PLLC
1100 NEW YORK AVENUE, N.W., SUITE 600
WASHINGTON
DC
20005-3934
US
|
Assignee: |
CoCensys, Inc.
|
Family ID: |
22713650 |
Appl. No.: |
09/819693 |
Filed: |
March 29, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60193441 |
Mar 31, 2000 |
|
|
|
Current U.S.
Class: |
514/151 ;
514/349; 546/307 |
Current CPC
Class: |
A61P 23/02 20180101;
A61P 9/06 20180101; C07D 213/74 20130101; A61P 25/28 20180101; A61P
25/08 20180101; A61P 25/18 20180101; A61P 25/00 20180101; A61P
43/00 20180101; A61P 9/10 20180101; A61P 21/02 20180101; A61P 25/04
20180101; A61P 25/24 20180101 |
Class at
Publication: |
514/151 ;
514/349; 546/307 |
International
Class: |
C07D 213/36; A61K
031/655 |
Claims
What is claimed is:
1. A compound having the Formula I: 5or a pharmaceutically
acceptable salt, prodrug or solvate thereof, wherein: R.sub.1 is
selected from the group consisting of hydrogen, alkyl, alkenyl,
alkynyl, halogen, haloalkyl, cycloalkyl, amino, aminoalkyl,
hydroxyalkyl, alkoxyalkyl, alkoxy, alkylthio, alkylsulfinyl,
alkylsulfonyl, carboxyalkyl, cyano, alkylamino, aminocarbonyl,
alkylaminocarbonyl, arylaminocarbonyl, aralkylaminocarbonyl,
alkylcarbonylamino, arylcarbonylamino, alkylcarbonyl,
heterocyclocarbonyl, aminosulfonyl, alkylaminosulfonyl, and
heterocyclosulfonyl, all of which can be optionally substituted;
R.sub.2 is hydrogen or C.sub.1-6 alkyl and R.sub.3 is hydrogen, or
R.sub.2 and R.sub.3 together form a bond; R.sub.4 is hydrogen or
C.sub.1-6 alkyl; R.sub.5, R.sub.6, R.sub.7, and R.sub.8 are
independently selected from the group consisting of hydrogen,
alkyl, alkenyl, alkynyl, halogen, haloalkyl, hydroxyalkyl, hydroxy,
nitro, amino, aminoalkyl, cyano, amide, carboxyalkyl, alkoxyalkyl,
ureido, acylamino, thiol, acyloxy, azido, alkoxy, carboxy,
carbonylamido and alkylthiol; X is one of O, S, NR.sub.9, or
CH.sub.2, wherein R.sub.9 is hydrogen or alkyl; and m is 0-3.
2. The compound of claim 1, wherein R.sub.1 is selected from the
group consisting of independently selected from the group
consisting of hydrogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6
alkenyl, C.sub.2-C.sub.6 alkynyl, amino(C.sub.1-C.sub.6)alkyl,
amino, C.sub.1-C.sub.6 alkylthio, cyano, C.sub.1-C.sub.6
alkylsulfinyl, hydroxy(C.sub.1-C.sub.6)alkyl, C.sub.1-C.sub.6
alkoxy, aminocarbonyl, C.sub.1-C.sub.6 alkylaminocarbonyl,
C.sub.6-C.sub.10 arylaminocarbonyl, C.sub.6-C.sub.10
aryl(C.sub.1-C.sub.6)alkylamino-carbonyl, C.sub.1-C.sub.6
alkylcarbonylamino, C.sub.6-C.sub.10 arylcarbonylamino,
C.sub.6-C.sub.10 aryl(C.sub.1-C.sub.6)alkylcarbonylamino,
C.sub.1-C.sub.6 alkylcarbonyl, heterocyclocarbonyl, aminosulfonyl,
C.sub.1-C.sub.6 alkylaminosulfonyl, C.sub.1-C.sub.6 alkylsulfonyl,
and heterocyclosulfonyl.
3. The compound of claim 2, wherein R.sub.1 is selected from the
group consisting of hydrogen, C.sub.1-C.sub.6 alkyl,
C.sub.1-C.sub.6 alkoxy, amino(C.sub.1-C.sub.6)alkyl,
C.sub.1-C.sub.6 alkylthio and aminocarbonyl.
4. The compound of claim 1, wherein R.sub.5, R.sub.6, R.sub.7, and
R.sub.8 are independently selected from the group consisting of
hydrogen, halo, C.sub.1-C.sub.6 haloalkyl, C.sub.6-C.sub.10 aryl,
C.sub.4-C.sub.7 cycloalkyl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6
alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.6-C.sub.10
aryl(C.sub.1-C.sub.6)alkyl, C.sub.6-C.sub.10
aryl(C.sub.2-C.sub.6)alkenyl, C.sub.6-C.sub.10
aryl(C.sub.2-C.sub.6)alkynyl, C.sub.1-C.sub.6 hydroxyalkyl, nitro,
amino, ureido, cyano, C.sub.1-C.sub.6 acylamido, hydroxy, thiol,
C.sub.1-C.sub.6 acyloxy, azido, C.sub.1-C.sub.6 alkoxy, or
carboxy.
5. The compound of claim 4, wherein R.sub.5 and R.sub.6 are both
hydrogen, R.sub.7 is hydrogen and R.sub.8 is a fluoro in the meta-
or para-position.
6. The compound of claim 1, wherein X is O or S.
7. The compound of claim 6, wherein X is O.
8. The compound of claim 1, having the Formula II: 6wherein
R.sub.1, R.sub.4, and R.sub.5-R.sub.8 are as defined in claim 1, X
is O or S and m is 0 or 1.
9. The compound of claim 8, wherein R.sub.1 is selected from the
group consisting of hydrogen, C.sub.1-C.sub.6 alkyl,
C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl,
amino(C.sub.1-C.sub.6)alkyl, amino, C.sub.1-C.sub.6 alkylthio,
cyano, C.sub.1-C.sub.6 alkylsulfinyl,
hydroxy(C.sub.1-C.sub.6)alkyl, C.sub.1-C.sub.6 alkoxy,
aminocarbonyl, C.sub.1-C.sub.6 alkylaminocarbonyl, C.sub.6-C.sub.10
arylaminocarbonyl, C.sub.6-C.sub.10
aryl(C.sub.1-C.sub.6)alkylamino-carbonyl, C.sub.1-C.sub.6
alkylcarbonylamino, C.sub.6-C.sub.10 arylcarbonylamino,
C.sub.6-C.sub.10 aryl(C.sub.1-C.sub.6)alkylcarbonylamino,
C.sub.1-C.sub.6 alkylcarbonyl, heterocyclocarbonyl, aminosulfonyl,
C.sub.1-C.sub.6 alkylaminosulfonyl, C.sub.1-C.sub.6 alkylsulfonyl,
and heterocyclosulfonyl.
10. The compound of claim 9, wherein R.sub.1 is selected from the
group consisting of hydrogen, C.sub.1-C.sub.6 alkyl,
C.sub.1-C.sub.6 alkoxy, amino(C.sub.1-C.sub.6)alkyl,
C.sub.1-C.sub.6 alkylthio and aminocarbonyl.
11. The compound of claim 1, wherein R.sub.5, R.sub.6, R.sub.7, and
R.sub.8 are independently selected from the group consisting of
hydrogen, halo, C.sub.1-C.sub.6 haloalkyl, C.sub.6-C.sub.10 aryl,
C.sub.4-C.sub.7 cycloalkyl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6
alkenyl, C.sub.2-C.sub.6 alkynyl, C.sub.6-C.sub.10
aryl(C.sub.1-C.sub.6)alkyl, C.sub.6-C.sub.10
aryl(C.sub.2-C.sub.6)alkenyl, C.sub.6-C.sub.10
aryl(C.sub.2-C.sub.6)alkynyl, C.sub.1-C.sub.6 hydroxyalkyl, nitro,
amino, ureido, cyano, C.sub.1-C.sub.6 acylamido, hydroxy, thiol,
C.sub.1-C.sub.6 acyloxy, azido, C.sub.1-C.sub.6 alkoxy, or
carboxy.
12. The compound of claim 11, wherein R.sub.5 and R.sub.6 are both
hydrogen, R.sub.7 is hydrogen and R.sub.8 is a fluoro in the meta-
or para-position.
13. The compound of claim 1, wherein said compound is:
N.sup.3-[4-(3-fluorobenzyloxy)benzyl]pyridine-2,3-diamine;
N.sup.3-[4-(3-fluorobenzyloxy)benzylidene]pyridine-2,3-diamine;
N.sup.3-[4-(4-fluorophenoxy)benzyl]pyridine-2,3-diamine; or
N.sup.3-[4-(4-fluorophenoxy)benzylidene]pyridine-2,3-diamine; or a
pharmaceutically acceptable salt, prodrug or solvate thereof.
14. A pharmaceutical composition, comprising a compound of claim 1
and a pharmaceutically acceptable carrier or diluent.
15. A method of treating a disorder responsive to the blockade of
sodium channels in a mammal suffering therefrom, comprising
administering to a mammal in need of such treatment an effective
amount of a compound of claim 1 or a pharmaceutically acceptable
salt, prodrug or solvate thereof.
16. A method for treating, preventing or ameliorating neuronal loss
following global and focal ischemia; treating, preventing or
ameliorating neurodegenerative conditions; treating, preventing or
ameliorating pain or tinnitus; treating, preventing or ameliorating
manic depression; providing local anesthesia; or treating
arrhythmias, or treating convulsions, comprising administering to a
mammal in need of such treatment an effective amount of a compound
of claim 1 or a pharmaceutically acceptable salt, prodrug or
solvate thereof.
17. The method of claim 16, wherein the method is for treating,
preventing or ameliorating pain and said pain is one of neuropathic
pain, surgical pain or chronic pain.
18. A method of alleviating or preventing seizure activity in an
animal subject, comprising administering to said animal in need of
such treatment an effective amount of a compound of claim 1 or a
pharmaceutically acceptable salt, prodrug or solvate thereof.
19. A compound of claim 1, wherein said compound is .sup.3H or
.sup.14C radiolabeled.
20. Use of a compound of claim 19 as a radioligand for its binding
site on the sodium channel.
Description
[0001] This application claims the priority benefit under 35 U.S.C.
.sctn. 119 of U.S. Provisional Application No. 60/193,441, filed
Mar. 31, 2000, the entirety of which is incorporated by reference
herein.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention is in the field of medicinal chemistry. In
particular, the invention relates to novel aminopyridines, and the
discovery that these compounds are anticonvulsants and act as
blockers of sodium (Na.sup.+) channels.
[0004] 2. Related Art
[0005] Several classes of therapeutically useful drugs, including
local anesthetics such as lidocaine and bupivacaine,
antiarrhythmics such as propafenone and amioclarone, and
anticonvulsants such as lamotrigine, phenytoin and carbamazepine,
have been shown to share a common mechanism of action by blocking
or modulating Na.sup.+ channel activity (Catterall, W. A., Trends
Pharmacol. Sci. 8:57-65 (1987)). Each of these agents is believed
to act by interfering with the rapid influx of Na.sup.+ ions.
[0006] Recently, other Na.sup.+ channel blockers such as BW619C89
and lifarizine have been shown to be neuroprotective in animal
models of global and focal ischemia and are presently in clinical
trials (Graham et al., J. Pharmacol. Exp. Ther. 269:854-859 (1994);
Brown et al., British J. Pharmacol 115:1425-1432 (1995)).
[0007] The neuroprotective activity of Na.sup.+ channel blockers is
due to their effectiveness in decreasing extracellular glutamate
concentration during ischemia by inhibiting the release of this
excitotoxic amino acid neurotransmitter. Studies have shown that
unlike glutamate receptor antagonists, Na.sup.+ channel blockers
prevent hypoxic damage to mammalian white matter (Stys et al., J.
Neurosci. 12:430-439 (1992)). Thus, they may offer advantages for
treating certain types of strokes or neuronal trauma where damage
to white matter tracts is prominent.
[0008] Another example of clinical use of a Na.sup.+ channel
blocker is riluzole. This drug has been shown to prolong survival
in a subset of patients with ALS (Bensimm et al., New Engl. J. Med.
330:585-591 (1994)) and has subsequently been approved by the FDA
for the treatment of ALS. In addition to the above-mentioned
clinical uses, carbamazepine, lidocaine and phenytoin are
occasionally used to treat neuropathic pain, such as from
trigeminal neurologia, diabetic neuropathy and other forms of nerve
damage (Taylor and Meldrum, Trends Pharmacol. Sci. 16:309-316
(1995)), and carbamazepine and lamotrigine have been used for the
treatment of manic depression (Denicott et al., J. Clin. Psychiatry
55: 70-76 (1994)). Furthermore, based on a number of similiarities
between chronic pain and tinnitus, (Moller, A. R. Am. J. Otol. 18:
577-585 (1997); Tonndorf, J. Hear. Res. 28: 271-275 (1987)) it has
been proposed that tinnitus should be viewed as a form of chronic
pain sensation (Simpson, J. J. and Davies, E. W. Tip. 20: 12-18
(1999)). Indeed, lignocaine and carbamazepine have been shown to be
efficacious in treating tinnitus (Majumdar, B. et al. Clin.
Otolaryngol. 8. 175-180 (1983); Donaldson, I. Laryngol. Otol. 95:
947-951 (1981)).
[0009] It has been established that there are at least five to six
sites on the voltage-sensitive Na.sup.+ channels which bind
neurotoxins specifically (Catterall, W. A., Science 242:50-61
(1988)). Studies have further revealed that therapeutic
antiarrhythmics, anticonvulsants and local anesthetics whose
actions are mediated by Na.sup.+ channels, exert their action by
interacting with the intracellular side of the Na.sup.+ channel and
allosterically inhibiting interaction with neurotoxin receptor site
2 (Catterall, W. A., Ann. Rev. Pharmacol. Toxicol. 10:15-43
(1980)).
SUMMARY OF THE INVENTION
[0010] The present invention is related to the discovery that
aminopyridines represented by Formula I are anticonvulsants and act
as blockers of sodium (Na.sup.+ ) channels.
[0011] The invention is also related with treating a disorder
responsive to the blockade of sodium channels in a mammal suffering
from excess activity of said channels by administering an effective
amount of a compound of Formula I as described herein.
[0012] The present invention is also directed to the use of a
compound of Formula I for the treatment of neuronal damage
following global and focal ischemia, and for the treatment or
prevention of neurodegenerative conditions such as amyotrophic
lateral sclerosis (ALS), for the treatment of tinnitus, as
antimanic depressants, as local anesthetics, as antiarrhythmics, as
anticonvulsants and for the treatment or prevention of diabetic
neuropathy and for the treatment of pain including both acute and
chronic pain and migraine headache.
[0013] One aspect of the present invention is directed to the novel
aminopyridines of Formula I.
[0014] Another aspect of the present invention is directed to the
novel compounds of Formula I as blockers of sodium channels.
[0015] A further aspect of the present invention is to provide a
method for treating, preventing or ameliorating neuronal loss
following global and focal ischemia; treating, preventing or
ameliorating pain including acute and chronic pain, and neuropathic
pain; treating, preventing or ameliorating convulsion and
neurodegenerative conditions; treating, preventing or ameliorating
manic depression; using as local anesthesics and anti-arrhythmics,
and treating tinnitus by administering a compound of Formula I to a
mammal in need of such treatment or use.
[0016] Also, an aspect of the present invention is to provide a
pharmaceutical composition useful for treating disorders responsive
to the blockade of sodium ion channels, containing an effective
amount of a compound of Formula I in a mixture with one or more
pharmaceutically acceptable carriers or diluents.
[0017] Further, the present invention is directed to .sup.3H and
.sup.14C radiolabeled compounds of Formula I and their use as
radioligands for their binding site on the sodium channel.
[0018] Additional embodiments and advantages of the invention will
be set forth in part in the description that follows, and in part
will be obvious from the description, or may be learned by practice
of the invention. The embodiments and advantages of the invention
will be realized and attained by means of the elements and
combinations particularly pointed out in the appended claims.
[0019] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The present invention arises out of the discovery that
aminopyridines of Formula I act as blockers of Na.sup.+ channels.
In view of this discovery compounds of Formula I are useful for
treating disorders responsive to the blockade of sodium ion
channels.
[0021] The compounds useful in this aspect of the present invention
are aminopyridines represented by Formula I: 2
[0022] or a pharmaceutically acceptable salt, prodrug or solvate
thereof, wherein:
[0023] R.sub.1 is selected from the group consisting of hydrogen,
alkyl, alkenyl, alkynyl, halogen, haloalkyl, cycloalkyl, amino,
aminoalkyl, hydroxyalkyl, alkoxyalkyl, alkoxy, alkylthio,
alkylsulfinyl, alkylsulfonyl, carboxyalkyl, cyano, alkylamino,
aminocarbonyl, alkylaminocarbonyl, arylaminocarbonyl,
aralkylaminocarbonyl, alkylcarbonylamino, arylcarbonylamino,
alkylcarbonyl, heterocyclocarbonyl, aminosulfonyl,
alkylaminosulfonyl, and heterocyclosulfonyl, all of which can be
optionally substituted;
[0024] R.sub.2 is hydrogen or C.sub.1-6 alkyl and R.sub.3 is
hydrogen, or R.sub.2 and R.sub.3 together form a bond;
[0025] R.sub.4 is hydrogen or C.sub.1-6 alkyl;
[0026] R.sub.5, R.sub.6, R.sub.7, and R.sub.8 are independently
selected from the group consisting of hydrogen, alkyl, alkenyl,
alkynyl, halogen, haloalkyl, hydroxyalkyl, hydroxy, nitro, amino,
aminoalkyl, cyano, amide, carboxyalkyl, alkoxyalkyl, ureido,
acylamino, thiol, acyloxy, azido, alkoxy, carboxy, carbonylamido
and alkylthiol;
[0027] X is one of O, S, NR.sub.9, or CH.sub.2, wherein R.sub.9 is
hydrogen or alkyl; and m is 0-3.
[0028] Preferably X is O or S, more preferably X is O.
[0029] One group of preferred compounds useful in the present
invention are aminopyridines represented by Formula II: 3
[0030] or a pharmaceutically acceptable salt, prodrug or solvate
thereof, wherein:
[0031] R.sub.1, R.sub.4-R.sub.8 are as defined above, X is O or S
and m is 0 or 1.
[0032] Preferably, R.sub.1 is selected from the group consisting of
hydrogen, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl,
C.sub.2-C.sub.6 alkynyl, amino(C.sub.1-C.sub.6)alkyl, amino,
C.sub.1-C.sub.6 alkylthio, cyano, C.sub.1-C.sub.6 alkylsulfinyl,
hydroxy(C.sub.1-C.sub.6)alkyl, C.sub.1-C.sub.6 alkoxy,
aminocarbonyl, C.sub.1-C.sub.6 alkylaminocarbonyl, C.sub.6-C.sub.10
arylaminocarbonyl, C.sub.6-C.sub.10
aryl(C.sub.1-C.sub.6)alkylaminocarbonyl, C.sub.1-C.sub.6
alkylcarbonylamino, C.sub.6-C.sub.10 arylcarbonylamino,
C.sub.6-C.sub.10 aryl(C.sub.1-C.sub.6)alkylcarbonylamino,
C.sub.1-C.sub.6 alkylcarbonyl, heterocyclocarbonyl, aminosulfonyl,
C.sub.1-C.sub.6 alkylaminosulfonyl, C.sub.1-C.sub.6 alkylsulfonyl,
and heterocyclosulfonyl, more preferably hydrogen, C.sub.1-C.sub.6
alkyl, C.sub.1-C.sub.6 alkoxy, amino(C.sub.1-C.sub.6)alkyl,
C.sub.1-C.sub.6 alkylthio and aminocarbonyl. Suitable heterocycles
in the heterocycle-containing groups include, for example,
N-morpholinyl, N-pyrrolidinyl and N-piperazinyl.
[0033] Preferably, R.sub.5, R.sub.6, R.sub.7, and R.sub.8 are
independently selected from the group consisting of hydrogen, halo,
C.sub.1-C.sub.6 haloalkyl, C.sub.6-C.sub.10 aryl, C.sub.4-C.sub.7
cycloalkyl, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl,
C.sub.2-C.sub.6 alkynyl, C.sub.6-C.sub.10
aryl(C.sub.1-C.sub.6)alkyl, C.sub.6-C.sub.10
aryl(C.sub.2-C.sub.6)alkenyl, C.sub.6-C.sub.10
aryl(C.sub.2-C.sub.6)alkynyl, C.sub.1-C.sub.6 hydroxyalkyl, nitro,
amino, ureido, cyano, C.sub.1-C.sub.6 acylamido, hydroxy, thiol,
C.sub.1-C.sub.6 acyloxy, azido, C.sub.1-C.sub.6 alkoxy, or carboxy.
Halo is preferably fluoro or chloro. The groups R.sub.5-R.sub.8
each take the place of a hydrogen atom that would otherwise be
present in any position on the aryl ring to which the R group is
attached. Especially preferred are compounds where R.sub.5 and
R.sub.6 are both hydrogen, R.sub.7 is hydrogen and R.sub.8 is a
fluoro in the meta- or para-position.
[0034] Since the compounds of Formula I are blockers of sodium
(Na.sup.+ ) channels, a number of diseases and conditions mediated
by sodium ion influx can be treated employing these compounds.
Therefore, the invention is related to a method of treating,
preventing or ameliorating neuronal loss associated with stroke,
global and focal ischemia, CNS trauma, hypoglycemia and surgery,
spinal cord trauma; as well as treating or ameliorating
neurodegenerative diseases including Alzheimer's disease,
amyotrophic lateral sclerosis, Parkinson's disease, treating or
ameliorating anxiety, convulsions, glaucoma, migraine headache, and
muscle spasm. The compounds of Formula I are also useful as
antitinnitus agents, antimanic depressants, as local anesthetics,
and as antiarrhythmics; as well as for treating, preventing or
ameliorating pain including surgical, chronic and neuropathic pain.
In each instance, the methods of the present invention require
administering to an animal in need of such treatment an effective
amount of a sodium channel blocker of the present invention, or a
pharmaceutically acceptable salt or prodrug thereof.
[0035] Exemplary preferred compounds that may be employed in this
method of invention include, without limitation:
[0036]
N.sup.3-[4-(3-fluorobenzyloxy)benzyl]pyridine-2,3-diamine;
[0037]
N.sup.3-[4-(3-fluorobenzyloxy)benzylidene]pyridine-2,3-diamine;
[0038] N.sup.3-[4-(4-fluorophenoxy)benzyl]pyridine-2,3-diamine;
and
[0039]
N.sup.3-[4-(4-fluorophenoxy)benzylidene]pyridine-2,3-diamine.
[0040] Useful aryl groups are C.sub.6-14 aryl, especially
C.sub.6-10 aryl. Typical C.sub.6-14 aryl groups include phenyl,
naphthyl, phenanthryl, anthracyl, indenyl, azulenyl, biphenyl,
biphenylenyl and fluorenyl groups.
[0041] Useful cycloalkyl groups are C.sub.3-8 cycloalkyl. Typical
cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl,
cyclohexyl and cycloheptyl.
[0042] Useful halo or halogen groups include fluorine, chlorine,
bromine and iodine.
[0043] Useful alkyl groups include straight-chained and branched
C.sub.1-10 alkyl groups, more preferably C.sub.1-6 alkyl groups.
Typical C.sub.1-10 alkyl groups include methyl, ethyl, propyl,
isopropyl, butyl, sec-butyl, tert-butyl, 3-pentyl, hexyl and octyl
groups. Also contemplated is a trimethylene group substituted on
two adjoining positions on the benzene ring of the compounds of the
invention.
[0044] Useful alkenyl groups are C.sub.2-6 alkenyl groups,
preferably C.sub.2-4 alkenyl.
[0045] Typical C.sub.2-4 alkenyl groups include ethenyl, propenyl,
isopropenyl, butenyl, and sec-butenyl.
[0046] Useful alkynyl groups are C.sub.2-6 alkynyl groups,
preferably C.sub.2-4 alkynyl. Typical C.sub.2-4 alkynyl groups
include ethynyl, propynyl, butynyl, and 2-butynyl groups.
[0047] Useful arylalkyl groups include any of the above-mentioned
C.sub.1-10 alkyl groups substituted by any of the above-mentioned
C.sub.6-14 aryl groups. Useful values include benzyl, phenethyl and
naphthylmethyl.
[0048] Useful arylalkenyl groups include any of the above-mentioned
C.sub.2-4 alkenyl groups substituted by any of the above-mentioned
C.sub.6-14 aryl groups.
[0049] Useful arylalkynyl groups include any of the above-mentioned
C.sub.2-4 alkynyl groups substituted by any of the above-mentioned
C.sub.6-14 aryl groups.
[0050] Useful values include phenylethynyl and phenylpropynyl.
[0051] Useful cycloalkylalkyl groups include any of the
above-mentioned C.sub.1-10 alkyl groups substituted by any of the
above-mentioned cycloalkyl groups.
[0052] Useful haloalkyl groups include C.sub.1-10 alkyl groups
substituted by one or more fluorine, chlorine, bromine or iodine
atoms, e.g. fluoromethyl, difluoromethyl, trifluoromethyl,
pentafluoroethyl, 1,1-difluoroethyl and trichloromethyl groups.
[0053] Useful hydroxyalkyl groups include C.sub.1-10 alkyl groups
substituted by hydroxy, e.g. hydroxymethyl, hydroxyethyl,
hydroxypropyl and hydroxybutyl groups.
[0054] Useful alkoxy groups include oxygen substituted by one of
the C.sub.1-10 alkyl groups mentioned above.
[0055] Useful alkylthio groups include sulfur substituted by one of
the C.sub.1-10 alkyl groups mentioned above.
[0056] Useful acylamino groups are any acyl group, particularly
C.sub.2-6 alkanoyl or C.sub.6-10 aryl(C.sub.2-6)alkanoyl attached
to an amino nitrogen, e.g. acetamido, propionamido, butanoylamido,
pentanoylamido, hexanoylamido, and benzoyl.
[0057] Useful acyloxy groups are any C.sub.1-6 acyl (alkanoyl)
attached to an oxy (--O--) group, e.g. acetoxy, propionoyloxy,
butanoyloxy, pentanoyloxy, hexanoyloxy and the like.
[0058] The term heterocyclic is used herein to mean saturated or
wholly or partially unsaturated 3-7 membered monocyclic, or 7-10
membered bicyclic ring system, which consists of carbon atoms and
from one to four heteroatoms independently selected from the group
consisting of O, N, and S, wherein the nitrogen and sulfur
heteroatoms can be optionally oxidized, the nitrogen can be
optionally quaternized, and including any bicyclic group in which
any of the above-defined heterocyclic rings is fused to a benzene
ring, and wherein the heterocyclic ring can be substituted on
carbon or on a nitrogen atom if the resulting compound is stable.
Examples include, but are not limited to, pyrrolidine, piperidine,
piperazine, morpholine, imidazoline, pyrazolidine, benzodiazepines,
and the like.
[0059] Useful heterocycloalkyl groups include any of the
above-mentioned C.sub.1-10 alkyl groups substituted by any of the
above-mentioned heterocyclic groups.
[0060] Useful alkylamino and dialkylamino groups are --NHR.sub.10
and --NR.sub.10R.sub.11, wherein R.sub.10 and R.sub.11 are
C.sub.1-10 alkyl groups.
[0061] Aminocarbonyl group is --C(O)NH.sub.2.
[0062] Useful alkylaminocarbonyl groups are carbonyl groups
substituted by --NHR.sub.10 and --NR.sub.10R.sub.11, wherein
R.sub.10 and R.sub.11 are C.sub.1-10 alkyl groups.
[0063] Useful alkylthiol groups include any of the above-mentioned
C.sub.1-10 alkyl groups substituted by a --SH group.
[0064] A carboxy group is --COOH.
[0065] An azido group is --N.sub.3.
[0066] An ureido group is --NH--C(O)--NH.sub.2.
[0067] An amino group is --NH.sub.2.
[0068] An amide group is an organic radical having --NHC(O)-- as a
functional group.
[0069] Optional substituents on R.sub.1 include any one of halo,
halo(C.sub.1-6)alkyl, aryl, heterocycle, cycloalkyl, C.sub.1-6
alkyl, C.sub.2-6 alkenyl, C.sub.2-6 alkynyl, aryl(C.sub.1-6)alkyl,
aryl(C.sub.2-6)alkenyl, aryl(C.sub.2-6)alkynyl,
cycloalkyl(C.sub.1-6)alky- l, heterocyclo(C.sub.1-6)alkyl,
hydroxy(C.sub.1-6)alkyl, amino(C.sub.1-6)alkyl,
carboxy(C.sub.1-6)alkyl, alkoxy(C.sub.1-6)alkyl, nitro, amino,
ureido, cyano, acylamino, hydroxy, thiol, acyloxy, azido, alkoxy,
carboxy, aminocarbonyl, and C.sub.1-6 alkylthiol groups mentioned
above. Preferred optional substituents include: halo,
halo(C.sub.1-6)alkyl, hydroxy(C.sub.1-6)alkyl,
amino(C.sub.1-6)alkyl, hydroxy, nitro, C.sub.1-6 alkyl, alkoxy and
amino.
[0070] The invention disclosed herein is meant to encompass all
pharmaceutically acceptable salts thereof of the disclosed
compounds. The pharmaceutically acceptable salts include, but are
not limited to, metal salts such as sodium salt, potassium salt,
secium salt and the like; alkaline earth metals such as calcium
salt, magnesium salt and the like; organic amine salts such as
triethylamine salt, pyridine salt, picoline salt, ethanolamine
salt, triethanolamine salt, dicyclohexylamine salt,
N,N'-dibenzylethylenediamine salt and the like; inorganic acid
salts such as hydrochloride, hydrobromide, sulfate, phosphate and
the like; organic acid salts such as formate, acetate,
trifluoroacetate, maleate, tartrate and the like; sulfonates such
as methanesulfonate, benzenesulfonate, p-toluenesulfonate, and the
like; amino acid salts such as arginate, asparginate, glutamate and
the like.
[0071] The invention disclosed herein is also meant to encompass
prodrugs of the disclosed compounds. Prodrugs are considered to be
any covalently bonded carriers which release the active parent drug
in vivo.
[0072] The invention disclosed herein is also meant to encompass
the in vivo metabolic products of the disclosed compounds. Such
products may result for example from the oxidation, reduction,
hydrolysis, amidation, esterification and the like of the
administered compound, primarily due to enzymatic processes.
Accordingly, the invention includes compounds produced by a process
comprising contacting a compound of this invention with a mammal
for a period of time sufficient to yield a metabolic product
thereof. Such products typically are identified by preparing a
radiolabelled compound of the invention, administering it
parenterally in a detectable dose to an animal such as rat, mouse,
guinea pig, monkey, or to man, allowing sufficient time for
metabolism to occur and isolating its conversion products from the
urine, blood or other biological samples.
[0073] The invention disclosed herein is also meant to encompass
the disclosed compounds being isotopically-labelled by having one
or more atoms replaced by an atom having a different atomic mass or
mass number. Examples of isotopes that can be incorporated into the
disclosed compounds include isotopes of hydrogen, carbon, nitrogen,
oxygen, phosphorous, fluorine and chlorine, such as .sup.2H,
.sup.3H, .sup.13C, .sup.14C, .sup.15N, 18O, .sup.17O, .sup.31P,
.sup.32P, 35S, .sup.18F, and .sup.36Cl, respectively.
[0074] Some of the compounds disclosed herein may contain one or
more asymmetric centers and my thus give rise to enantiomers,
diastereomers, and other stereoisomeric forms. The present
invention is also meant to encompass all such possible forms as
well as their racemic and resolved forms and mixtures thereof. When
the compounds described herein contain olefinic double bonds or
other centers of geometric asymmetry, and unless specified
otherwise, it is intended to include both E and Z geometric
isomers. All tautomers are intended to be encompassed by the
present invention as well.
[0075] As used herein, the term "stereoisomers" is a general term
for all isomers of individual molecules that differ only in the
orientation of their atoms in space. It includes enantiomers and
isomers of compounds with more than one chiral center that are not
mirror images of one another (diastereomers).
[0076] The term "chiral center" refers to a carbon atom to which
four different groups are attached.
[0077] The term "enantiomer" or "enantiomeric" refers to a molecule
that is nonsuperimposeable on its mirror image and hence optically
active wherein the enantiomer rotates the plane of polarized light
in one direction and its mirror image rotates the plane of
polarized light in the opposite direction.
[0078] The term "racemic" refers to a mixture of equal parts of
enantiomers and which is optically inactive.
[0079] The term "resolution" refers to the separation or
concentration or depletion of one of the two enantiomeric forms of
a molecule.
[0080] The invention is also directed to a method for treating
disorders responsive to the blockade of sodium channels in animals
suffering thereof. Particular preferred embodiments of the
aminopyridine compounds for use in method of this invention are
represented by previously defined Formulae I-II.
[0081] The compounds of this invention may be prepared using
methods known to those skilled in the art. Aminopyridine
derivatives according to the invention can be prepared, for
example, as illustrated by examplary reactions in Scheme 1.
Formation of the aryl substituted aminopyridine was accomplished as
described by Curtin, M. L. et al. (J. Med. Chem. 41:74-95 (1998))
and Khanna, I. K. et al. (J. Org. Chem. 60: 960-965 (1995)). 4
[0082] wherein R.sub.4-R.sub.8 are as defined above. Suitable
methods for preparing different aldehyde and ketone starting
compounds are described, for example, in U.S. Provisional Patent
Application No. 60/188,188, filed Mar. 10, 2000, and U.S.
Non-Provisional Patent Application No. 09/533,864, filed Mar. 24,
2000 (Attorney Ref:1483.0360001). Other suitable methods are
described by Dimmock et al. (J. Med. Chem. 39: 3984-3997 (1996))
and Pevarello et al. (J. Med. Chem. 41: 579-590 (1998)).
[0083] The compounds of the present invention were assessed by
electrophysiological assays in dissociated hippocampal neurons for
sodium channel blocker activity. These compounds also could be
assayed for binding to the neuronal voltage-dependent sodium
channel using rat forebrain membranes and [.sup.3H]BTX-B.
[0084] Sodium channels are large transmembrane proteins that are
expressed in various tissues. They are voltage sensitive channels
and are responsible for the rapid increase of Na.sup.+ permeability
in response to depolarization associated with the action potential
in many excitable cells including muscle, nerve and cardiac
cells.
[0085] One aspect of the present invention is the discovery of the
mechanism of action of the compounds herein described as specific
Na.sup.+ channel blockers. Based upon the discovery of this
mechanism, these compounds are contemplated to be useful in
treating or preventing neuronal loss due to focal or global
ischemia, and in treating or preventing neurodegenerative disorders
including ALS, anxiety, and epilepsy. They are also expected to be
effective in treating, preventing or ameliorating neuropathic pain,
surgical pain, chronic pain and tinnitus. The compounds are also
expected to be useful as antiarrhythmics, anesthetics and antimanic
depressants.
[0086] The present invention is directed to compounds of Formulae
I-II that are blockers of voltage-sensitive sodium channels.
According to the present invention, those compounds having
preferred sodium channel blocking properties exhibit an IC.sub.50
of about 100 .mu.M or less in the electrophysiological assay
described herein. Preferably, the compounds of the present
invention exhibit an IC.sub.50 of 10 .mu.M or less. Most
preferably, the compounds of the present invention exhibit an
IC.sub.50 of about 1.0 .mu.M or less. Substituted heteroaryl
compounds of the present invention may be tested for their Na.sup.+
channel blocking activity by the following electrophysiological and
binding assays.
[0087] The invention is also directed to .sup.3H and .sup.14C
radiolabeled compounds of Formula I and their use as radioligands
for their binding site on the sodium channel. For example, one use
of the labeled compounds of the invention is the characterization
of specific receptor binding. Another use of the labeled compounds
of the invention is an alternative to animal testing for the
evaluation of structure-activity relationships. The receptor assay
is performed at a fixed concentration of a labeled compound of
Formula I and at increasing concentrations of a test compound in a
competition assay.
[0088] Tritiated compounds of Formula I can be prepared by
introducing tritium into the compound of Formula I by, for example,
catalytic dehalogenation with tritium. This method includes
reacting a suitably halogen-substituted precursor of a compound of
Formula I with tritium gas in the presence of a suitable catalyst,
for example Pd/C, in the presence or absence of a base. Other
suitable methods for preparing tritiated compounds can be found in
Filer, Isotopes in the Physical and Biomedical Sciences, Vol. 1,
Labeled Compounds (Part A), Chapter 6. .sup.14C-labeled compounds
can be prepared by employing starting materials having a .sup.14C
carbon.
[0089] Electrophysiological Assay:
[0090] Cell preparation: HEK-293 cells stably expressing the hSkM1
isoform of Na.sup.+ channels (generous gift from Dr. A. L. George,
Vanderbilt University Medical School) were cultured using standard
techniques, as described previously (Verdoorn, T. A, et al., Neuron
4:919-928 (1990)). For electrophysiology, cells were plated onto 35
mm Petri dishes (pre-coated with poly-D-lysine) at a density of
1:40 on the day of re-seeding from confluent cultures. Our
experience has been that cells are suitable for recordings for 2-3
days after plating.
[0091] Patch-clamp recordings of voltage-sensitive Na.sup.+
currents: Whole-cell voltage-clamp recordings were made using
conventional patch-clamp techniques (Hamill et al., Pfluegers Arch.
391:85-100 (1981)) with an Axopatch 200A amplifier (Axon
Instruments, Foster City, Calif.). Recordings were made within 2-3
hours after neuron dissociation. The recording chamber was
continuously superfused with the external solution (150 mM NaCl,
5.4 mM KCl, 1.8 mM CaCl.sub.2, 1 mM MgCl.sub.2, 10 mM HEPES, 10 mM
glucose, pH 7.4 (NaOH)) at a speed of about 1 mL/min. Recording
pipettes were pulled from thick-walled capillaries (WPI, Sarasota,
Fla.) and fire-polished. The pipette resistances ranged from 1 to 3
M.OMEGA. when the pipettes were filled with internal solution
containing (in mM): 110 CsF, 10 NaCl, 5 MgCl.sub.2, 11 EGTA, 10
HEPES, pH adjusted to 7.4 with CsOH. Osmolality was set with a
difference of 15-20 mmol/kg between external and internal solutions
(lower inside the cell). Drugs and intervening wash-outs were
applied through a linear array of flow pipes (Drummond Microcaps, 2
.mu.L, 64-mm length). Compounds are dissolved in dimethylsulfoxide
(DMSO) to make a 30 mM stock solution, which was subsequently
diluted into the external solution to give final concentrations of
0.1-100 .mu.M. At the highest (1%) concentration, DMSO inhibited
the size of Na.sup.+ current only slightly. Currents were recorded
at room temperature (22-25.degree. C.), filtered at 5 kHz with an
active 8-pole Bessel filter (Frequency Devices, Haverhill, Mass.),
digitized at 10-50 .mu.s intervals, and stored using Digidata 1200
analog/digital interface with Pclamp6/Clampex software (Axon
Instruments). Series resistance was cancelled typically by 75% when
necessary. The inhibitory potency of drugs was assessed by
measuring reductions in the peak amplitude of Na.sup.+ currents
induced by increasing concentrations of compounds tested. Na.sup.+
currents were elicited by stepping membrane voltage from holding
potentials over the range -100 mV to -50 mV, to a pulse potential
of -10 mV. The test pulse duration was 5-10 msec, repeated at a
frequency .ltoreq.1 Hz. Concentration-inhibition curves were fitted
with equation 1:
I/I.sub.control=1/(1+([compound]/IC.sub.50)) Eq. 1
[0092] where I.sub.control is the maximal Na.sup.+ current in the
absence of antagonist, [compound] is the drug concentration, and
IC.sub.50 is the concentration of compound that produces half
maximal inhibition.
[0093] In vitro Binding Assay:
[0094] The ability of compounds of the present invention to
modulate either site 1 or site 2 of the Na.sup.+ channel was
determined following the procedures fully described in Yasushi, J.
Biol. Chem. 261:6149-6152 (1986) and Creveling, Mol. Pharmacol.
23:350-358 (1983), respectively. Rat forebrain membranes were used
as sources of Na.sup.+ channel proteins. The binding assays were
conducted in 130 .mu.M choline chloride at 37.degree. C. for
60-minute incubation with [.sup.3H] saxitoxin and [.sup.3H]
batrachotoxin as radioligands for site 1 and site 2,
respectively.
[0095] In vivo Pharmacology:
[0096] The compounds of the present invention may be tested for in
vivo anticonvulsant activity after i.v., p.o. or i.p. injection
using a number of anticonvulsant tests in mice, including the
maximum electroshock seizure test (MES). Maximum electroshock
seizures were induced in male NSA mice weighing between 15-20 g and
male Sprague-Dawley rats weighing between 200-225 g by application
of current (50 mA, 60 pulses/sec, 0.8 msec pulse width, 1 sec
duration, D.C., mice; 99 mA, 125 pulses/sec, 0.8 msec pulse width,
2 sec duration, D.C., rats) using a Ugo Basile ECT device (Model
7801). Mice were restrained by gripping the loose skin on their
dorsal surface and saline-coated corneal electrodes were held
lightly against the two corneae. Rats were allowed free movement on
the bench top and ear-clip electrodes were used. Current was
applied and animals were observed for a period of up to 30 seconds
for the occurrence of a tonic hindlimb extensor response. A tonic
seizure was defined as a hindlimb extension in excess of 90 degrees
from the plane of the body. Results were treated in a quantal
manner.
[0097] The compounds may be tested for their antinociceptive
activity in the formalin model as described in Hunskaar, S., O. B.
Fasmer, and K. Hole, J. Neurosci. Methods 14: 69-76 (1985). Male
Swiss Webster NIH mice (20-30 g; Harlan, San Diego, Calif.) were
used in all experiments. Food was withdrawn on the day of
experiment. Mice were placed in Plexiglass jars for at least 1 hour
to accommodate to the environment. Following the accommodation
period mice were weighed and given either the compound of interest
administered i.p. or p.o., or the appropriate volume of vehicle
(10% Tween-80). Fifteen minutes after the i.p. dosing, and 30
minutes after the p.o. dosing mice were injected with formalin (20
.mu.L of 5% formaldehyde solution in saline) into the dorsal
surface of the right hind paw. Mice were transferred to the
Plexiglass jars and monitored for the amount of time spent licking
or biting the injected paw. Periods of licking and biting were
recorded in 5 minute intervals for 1 hour after the formalin
injection. All experiments were done in a blinded manner during the
light cycle. The early phase of the formalin response was measured
as licking/biting between 0-5 minutes, and the late phase was
measured from 15-50 minutes. Differences between vehicle and drug
treated groups were analyzed by one-way analysis of variance
(ANOVA). A P value .ltoreq.0.05 was considered significant. Having
activity in blocking the acute and second phase of formalin-induced
paw-licking activity, the compounds are considered to be
efficacious for acute and chronic pain.
[0098] The compounds may be tested for their potential for the
treatment of chronic pain (antiallodynic and antihyperalgesic
activities) in the Chung model of peripheral neuropathy. Male
Sprague-Dawley rats weighing between 200-225 g were anesthetized
with halothane (1-3% in a mixture of 70% air and 30% oxygen) and
their body temperature controlled during anesthesia through use of
a homeothermic blanket. A 2-cm dorsal midline incision was then
made at the L5 and L6 level and the para-vertibral muscle groups
retracted bilaterally. L5 and L6 spinal nerves were then be
exposed, isolated, and tightly ligated with 6-0 silk suture. A sham
operation was performed exposing the contralateral L5 and L6 spinal
nerves as a negative control.
[0099] Tactile Allodynia: Rats were transferred to an elevated
testing cage with a wire mesh floor and allowed to acclimate for
five to ten minutes. A series of Semmes-Weinstein monofilaments
were applied to the plantar surface of the hindpaw to determine the
animal's withdrawal threshold. The first filament used possessed a
buckling weight of 9.1 gms (0.96 log value) and was applied up to
five times to see if it elicited a withdrawal response. If the
animal had a withdrawal response then the next lightest filament in
the series would be applied up to five times to determine if it
could elicit a response. This procedure was repeated with
subsequent lesser filaments until there was no response and the
lightest filament that elicited a response was recorded. If the
animal did not have a withdrawal response from the initial 9.1 gms
filament then subsequent filaments of increased weight were applied
until a filament elicited a response and this filament was then
recorded. For each animal, three measurements were made at every
time point to produce an average withdrawal threshold
determination. Tests were performed prior to and at 1, 2, 4 and 24
hours post drug administration. Tactile allodynia and mechanical
hyperalgesia tests were conducted concurrently.
[0100] Mechanical Hyperalgesia: Rats were transferred to an
elevated testing cage with a wire mesh floor and allowed to
acclimate for five to ten minutes. A slightly blunted needle was
touched to the plantar surface of the hindpaw causing a dimpling of
the skin without penetrating the skin. Administration of the needle
to control paws typically produced a quick flinching reaction, too
short to be timed with a stopwatch and arbitrarily given a
withdrawal time of 0.5 second. The operated side paw of neuropathic
animals exhibited an exaggerated withdrawal response to the blunted
needle. A maximum withdrawal time of ten seconds was used as a
cutoff time. Withdrawal times for both paws of the animals were
measured three times at each time point with a five-minute recovery
period between applications. The three measures were used to
generate an average withdrawal time for each time point. Tactile
allodynia and mechanical hyperalgesia tests were conducted
concurrently.
[0101] The compounds may be tested for their neuroprotective
activity after focal and global ischemia produced in rats or
gerbils according to the procedures described in Buchan et al.
(Stroke, Suppl. 148-152 (1993)) and Sheardown et al. (Eur. J.
Pharmacol. 236:347-353 (1993)) and Graham et al. (J. Pharmacol.
Exp. Therap. 276:1-4 (1996)).
[0102] The compounds may be tested for their neuroprotective
activity after traumatic spinal cord injury according to the
procedures described in Wrathall et al. (Exp. Neurology 137:119-126
(1996)) and Iwasaki et al. (J. Neuro Sci. 134:21-25 (1995)).
[0103] Compositions within the scope of this invention include all
compositions wherein the compounds of the present invention are
contained in an amount that is effective to achieve its intended
purpose. While individual needs vary, determination of optimal
ranges of effective amounts of each component is within the skill
of the art. Typically, the compounds may be administered to
mammals, e.g. humans, orally at a dose of 0.0025 to 50 mg/kg, or an
equivalent amount of the pharmaceutically acceptable salt thereof,
per day of the body weight of the mammal being treated for
epilepsy, neurodegenerative diseases, anesthetic, arrhythmia, manic
depression, and pain. For intramuscular injection, the dose is
generally about one-half of the oral dose.
[0104] In the method of treatment or prevention of neuronal loss in
global and focal ischemia, brain and spinal cord trauma, hypoxia,
hypoglycemia, status epilepsy and surgery, the compound can be
administrated by intravenous injection at a dose of about 0.025 to
about 10 mg/kg.
[0105] The unit oral dose may comprise from about 0.01 to about 50
mg, preferably about 0.1 to about 10 mg of the compound. The unit
dose may be administered one or more times daily as one or more
tablets each containing from about 0.1 to about 10, conveniently
about 0.25 to 50 mg of the compound or its solvates.
[0106] In addition to administering the compound as a raw chemical,
the compounds of the invention may be administered as part of a
pharmaceutical preparation containing suitable pharmaceutically
acceptable carriers comprising excipients and auxiliaries which
facilitate processing of the compounds into preparations which can
be used pharmaceutically. Preferably, the preparations,
particularly those preparations which can be administered orally
and which can be used for the preferred type of administration,
such as tablets, dragees, and capsules, and also preparations which
can be administered rectally, such as suppositories, as well as
suitable solutions for administration by injection or orally,
contain from about 0.01 to 99 percent, preferably from about 0.25
to 75 percent of active compound(s), together with the
excipient.
[0107] Also included within the scope of the present invention are
the non-toxic pharmaceutically acceptable salts of the compounds of
the present invention. Acid addition salts are formed by mixing a
solution of the particular heteroaryl compound of the present
invention with a solution of a pharmaceutically acceptable
non-toxic acid such as hydrochloric acid, fumaric acid, maleic
acid, succinic acid, acetic acid, citric acid, tartaric acid,
carbonic acid, phosphoric acid, oxalic acid, dichloroacetic acid,
and the like. Basic salts are formed by mixing a solution of the
heteroaryl compound of the present invention with a solution of a
pharmaceutically acceptable non-toxic base such as sodium
hydroxide, potassium hydroxide, choline hydroxide, sodium carbonate
and the like.
[0108] The pharmaceutical compositions of the invention may be
administered to any animal that may experience the beneficial
effects of the compounds of the invention. Foremost among such
animals are mammals, e.g., humans, although the invention is not
intended to be so limited.
[0109] The pharmaceutical compositions of the present invention may
be administered by any means that achieve their intended purpose.
For example, administration may be by parenteral, subcutaneous,
intravenous, intramuscular, intraperitoneal, transdermal, or buccal
routes. Alternatively, or concurrently, administration may be by
the oral route. The dosage administered will be dependent upon the
age, health, and weight of the recipient, kind of concurrent
treatment, if any, frequency of treatment, and the nature of the
effect desired.
[0110] The pharmaceutical preparations of the present invention are
manufactured in a manner which is itself known, for example, by
means of conventional mixing, granulating, dragee-making,
dissolving, or lyophilizing processes. Thus, pharmaceutical
preparations for oral use can be obtained by combining the active
compounds with solid excipients, optionally grinding the resulting
mixture and processing the mixture of granules, after adding
suitable auxiliaries, if desired or necessary, to obtain tablets or
dragee cores.
[0111] Suitable excipients are, in particular, fillers such as
saccharides, for example lactose or sucrose, mannitol or sorbitol,
cellulose preparations and/or calcium phosphates, for example
tricalcium phosphate or calcium hydrogen phosphate, as well as
binders such as starch paste, using, for example, maize starch,
wheat starch, rice starch, potato starch, gelatin, tragacanth,
methyl cellulose, hydroxypropylmethylcellulose, sodium
carboxymethylcellulose, and/or polyvinyl pyrrolidone. If desired,
disintegrating agents may be added such as the above-mentioned
starches and also carboxymethyl-starch, cross-linked polyvinyl
pyrrolidone, agar, or alginic acid or a salt thereof, such as
sodium alginate. Auxiliaries are, above all, flow-regulating agents
and lubricants, for example, silica, talc, stearic acid or salts
thereof, such as magnesium stearate or calcium stearate, and/or
polyethylene glycol. Dragee cores are provided with suitable
coatings that, if desired, are resistant to gastric juices. For
this purpose, concentrated saccharide solutions may be used, which
may optionally contain gum arabic, talc, polyvinyl pyrrolidone,
poly-ethylene glycol and/or titanium dioxide, lacquer solutions and
suitable organic solvents or solvent mixtures. In order to produce
coatings resistant to gastric juices, solutions of suitable
cellulose preparations such as acetylcellulose phthalate or
hydroxypropymethyl-cellulose phthalate, are used. Dye stuffs or
pigments may be added to the tablets or dragee coatings, for
example, for identification or in order to characterize
combinations of active compound doses.
[0112] Other pharmaceutical preparations which can be used orally
include push-fit capsules made of gelatin, as well as soft, sealed
capsules made of gelatin and a plasticizer such as glycerol or
sorbitol. The push-fit capsules can contain the active compounds in
the form of granules which may be mixed with fillers such as
lactose, binders such as starches, and/or lubricants such as talc
or magnesium stearate and, optionally, stabilizers. In soft
capsules, the active compounds are preferably dissolved or
suspended in suitable liquids, such as fatty oils, or liquid
paraffin. In addition, stabilizers may be added.
[0113] Possible pharmaceutical preparations, which can be used
rectally, include, for example, suppositories, which consist of a
combination of one or more of the active compounds with a
suppository base. Suitable suppository bases are, for example,
natural or synthetic triglycerides, or paraffin hydrocarbons. In
addition, it is also possible to use gelatin rectal capsules which
consist of a combination of the active compounds with a base.
Possible base materials include, for example, liquid triglycerides,
polyethylene glycols, or paraffin hydrocarbons.
[0114] Suitable formulations for parenteral administration include
aqueous solutions of the active compounds in water-soluble form,
for example, water-soluble salts and alkaline solutions. In
addition, suspensions of the active compounds as appropriate oily
injection suspensions may be administered. Suitable lipophilic
solvents or vehicles include fatty oils, for example, sesame oil,
or synthetic fatty acid esters, for example, ethyl oleate or
triglycerides or polyethylene glycol-400 (the compounds are soluble
in PEG-400). Aqueous injection suspensions may contain substances
which increase the viscosity of the suspension, and include, for
example, sodium carboxymethyl cellulose, sorbitol, and/or dextran.
Optionally, the suspension may also contain stabilizers.
[0115] The following examples are illustrative, but not limiting,
of the method and compositions of the present invention. Other
suitable modifications and adaptations of the variety of conditions
and parameters normally encountered in clinical therapy and which
are obvious to those skilled in the art are within the spirit and
scope of the invention.
EXAMPLE 1
N.sup.3-[4-(3-Fluorobenzyloxy)benzyl]pyridine-2,3-diamine
[0116] a) 4-(3-Fluorobenzyloxy)benzaldehyde:
[0117] A mixture of 4-hydroxybenzaldehyde (3.1 g, 24.8 mmol),
3-fluorobenzylchloride (2.4 mL, 19.8 mmol), potassium carbonate
(74.5 mmol), and catalytic sodium iodide in ethanol was refluxed
for several hours. The reaction was monitored by TLC. When the
reaction was complete, the mixture was cooled to room temperature,
and partitioned between ethyl acetate and an aqueous sodium
hydroxide solution (2N). The separated organic layer was washed one
more time with an aqueous sodium hydroxide solution (2N), dried
over sodium sulfate, filtered and evaporated under reduced pressure
to give the product as a yellow oil. This material was carried on
without further purification. .sup.1H NMR (CDCl.sub.3): .delta.
9.89 (s, 1H), 7.84 (d, J=8.7 Hz, 2H), 7.4-7.1 (m, 4H), 7.07 (d,
J=9.0 Hz, 2H), 5.15 (s, 2H).
[0118] b)
N.sup.3-[4-(3-Fluorobenzyloxy)benzylidene]pyridine-2,3-diamine:
[0119] A mixture of 4-(3-fluorobenzyloxy)benzaldehyde (0.51 g, 2.2
mmol), 2,3-diaminopyridine (0.33 g, 2.96 mmol), dried molecular
sieves (4 .ANG., 2.1 g) in THF was refluxed for 5 hours, then
stirred at room temperature overnight. The mixture was filtered and
the filtrate was evaporated under reduced pressure to give a yellow
solid. The crude product was purified by column chromatography
affording 448 mg (63%) of the product as a yellow solid. .sup.1H
NMR (CDCl.sub.3): .delta. 8.44 (s, 1H), 7.95 (dd, J=5.1, 1.5 Hz,
1H), 7.86 (d, J=8.7 Hz, 2H), 7.40-7.33 (m, 1H), 7.22-7.15 (m, 3H),
7.06-7.01 (m, 3H), 6.66 (dd, J=7.5, 4.8 Hz, 1H), 5.14 (s, 2H), 4.96
(bs, 2H).
[0120] c)
N.sup.3-[4-(3-Fluorobenzyloxy)benzyl]pyridine-2,3-diamine:
[0121] A mixture of
N.sup.3-[4-(3-fluorobenzyloxy)benzylidene]pyridine-2,3- -diamine
(0.4 g, 1.24 mmol), and sodium borohydride (0.48 g, 12.4 mmol) in
ethanol was refluxed overnight. The solution was cooled to room
temperature, then partitioned between ethyl acetate and water. The
organic layer was dried over sodium sulfate, filtered, and
evaporated under reduced pressure to give a yellow oil. The oil was
purified by column chromatography to give 287 mg (72%) of the final
product as a yellow solid, mp 91-93.degree. C. .sup.1H NMR
(CDCl.sub.3): .delta. 7.61 (d, J=5.1 Hz, 1H), 7.38-7.26 (m, 1H),
7.30 (d, J=8.4 Hz, 2H), 7.20-7.14 (m, 2H), 7.04-6.93 (m, 3H), 6.82
(d, J=7.8 Hz, 1H), 6.68 (dd, J=5.1, 7.2 Hz, 1H), 5.06 (s, 2H), 4.22
(d, J=4.8 Hz, 2H), 4.20 (bs, 2H), 3.49 (bs, 1H).
EXAMPLE 2
N.sup.3-[4-(4-Fluorophenoxy)benzyl]pyridine-2,3-diamine
[0122] N.sub.3[4-(4-Fluorophenoxy)benzyl]pyridine-2,3-diamine was
prepared by the method of Example 1 starting with
4-(4-fluorophenoxy)benzaldehyde. .sup.1H NMR (CDCl.sub.3): .delta.
7.63 d, J=5.1 Hz, 1H), 7.33 (d, J=8.4 Hz, 2H), 7.06-6.94 (m, 6H),
6.82 (d, J=6.6 Hz, 1H), 6.69 (dd, J=4.8, 7.2 Hz, 1H), 4.26 (d,
J=5.1 Hz, 2H), 4.18 (bs, 2H), 3.51 (bs, 1H); mp 117-118.degree.
C.
EXAMPLE 3
N.sup.3-[4-(4-Fluorophenoxy)benzyl]pyridine-2,3-diamine as
Anticonvulsant
[0123] The ability of
N.sup.3-[4-(4-fluorophenoxy)benzyl]pyridine-2,3-diam- ine to block
maximal electroshock-induced seizures (MES) was determined
according to the method above.
[0124] N.sup.3-[4-(4-Fluorophenoxy)benzyl]pyridine-2,3-diamine was
injected i.v. to mice 15 minutes before the test procedure. The
compound exhibited protection against MES with an ED.sub.50 (the
dose protecting 50% of animals) of 10 mg/kg.
[0125] N.sup.3-[4-(3-Fluorobenzyloxy)benzyl]pyridine-2,3-diamine
was tested similarly and it exhibited protection against MES with
an ED.sub.50 of 2.9 mg/kg.
EXAMPLE 4
Activity of N.sup.3-[4-(4-fluorophenoxy)benzyl]pyridine-2,3-diamine
as Sodium Channel Blocker
[0126] N.sup.3-[4-(4-Fluorophenoxy)benzyl]pyridine-2,3-diamine was
tested in the electrophysiological and binding assays as described
above and produced dose-dependent inhibition of voltage-gated
sodium currents recorded in HEK-293 cells stably expressing the
hSKMI isoform of Na.sup.+ channels. The blocking effect of this
compound on Na.sup.+ currents was highly sensitive to the holding
voltage, indicating that
N.sup.3-[4-(4-fluorophenoxy)benzyl]pyridine-2,3-diamine binds to
voltage-sensitive Na.sup.+ channels in their inactivated states and
has weak potency towards Na.sup.+ channels in their resting states
(Ragsdale et al., Mol. Pharmacol. 40:756-765 (1991); Kuo and Bean,
Mol. Pharmacol. 46:716-725 (1994)). The apparent antagonist
dissociation constant K.sub.i (the concentration of a compound that
produces half maximal inhibition) of this compound for inactivated
sodium channels is 0.06 .mu.M.
[0127] Having now fully described this invention, it will be
understood by those of ordinary skill in the art that the same can
be performed within a wide and equivalent range of conditions,
formulations and other parameters without affecting the scope of
the invention or any embodiment thereof.
[0128] Other embodiments of the invention will be apparent to those
skilled in the art from consideration of the specification and
practice of the invention disclosed herein. It is intended that the
specification and examples be considered as exemplary only, with a
true scope and spirit of the invention being indicated by the
following claims.
[0129] All patents and publications cited herein are fully
incorporated by reference herein in their entirety.
* * * * *