U.S. patent application number 13/169331 was filed with the patent office on 2011-10-20 for neurotherapeutic treatment for sexual dysfunction.
This patent application is currently assigned to Revaax Pharmaceuticals, LLC. Invention is credited to Gary A. Koppel.
Application Number | 20110257147 13/169331 |
Document ID | / |
Family ID | 23153146 |
Filed Date | 2011-10-20 |
United States Patent
Application |
20110257147 |
Kind Code |
A1 |
Koppel; Gary A. |
October 20, 2011 |
NEUROTHERAPEUTIC TREATMENT FOR SEXUAL DYSFUNCTION
Abstract
A method for improving sexual function is described. A mammal
suffering from sexual dysfunction or otherwise in need of enhanced
sexual function is administered a compound selected from those that
are capable of inhibiting the activity of .beta.-lactams,
penicillin-binding protein, carboxypeptidase. Such compounds,
including particularly .beta.-lactam ring-containing compounds, can
be used to formulate pharmaceutical formulations useful for
improving sexual function.
Inventors: |
Koppel; Gary A.;
(Indianapolis, IN) |
Assignee: |
Revaax Pharmaceuticals, LLC
Indianapolis
IN
|
Family ID: |
23153146 |
Appl. No.: |
13/169331 |
Filed: |
June 27, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11562311 |
Nov 21, 2006 |
7998991 |
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13169331 |
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10175092 |
Jun 18, 2002 |
7166626 |
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11562311 |
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60299060 |
Jun 18, 2001 |
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Current U.S.
Class: |
514/192 ;
514/203; 514/210.06; 514/210.08 |
Current CPC
Class: |
A61K 31/43 20130101;
A61K 31/424 20130101; A61K 31/431 20130101; A61P 15/10 20180101;
A61K 31/546 20130101; A61K 31/5365 20130101; A61K 31/545
20130101 |
Class at
Publication: |
514/192 ;
514/210.06; 514/203; 514/210.08 |
International
Class: |
A61K 31/431 20060101
A61K031/431; A61K 31/43 20060101 A61K031/43; A61P 15/10 20060101
A61P015/10; A61K 31/5365 20060101 A61K031/5365; A61K 31/545
20060101 A61K031/545; A61K 31/424 20060101 A61K031/424; A61K 31/546
20060101 A61K031/546 |
Claims
1. A method for improving sexual function in a mammal suffering
from or disposed to develop sexual dysfunction or otherwise in need
of enhanced sexual function, said method comprising the step of
administering to said mammal a .beta.-lactam compound capable of
inhibiting the activity of a bacterial enzyme selected from
.beta.-lactamase or penicillin binding protein or a
carboxypeptidase, where the .beta.-lactam compound is administered
in an amount therapeutically effective to treat the sexual
dysfunction or enhance the sexual function of said mammal.
2.-31. (canceled)
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C .sctn.119(e)
to U.S. Provisional Application Ser. No. 60/299,060, filed on Jun.
18, 2001.
FIELD OF THE INVENTION
[0002] This invention relates to a method for improving sexual
function. More particularly, this invention is directed to the use
of compounds capable of exhibiting specific binding affinity to and
inhibiting the activity of certain bacterial enzymes and
structurally related mammalian enzymes for improving sexual
function and for reducing or eliminating the indicia of sexual
dysfunction in a mammal either suffering from such disability or
exposed to conditions tending to engender such disability.
BACKGROUND OF THE INVENTION
[0003] Sexual dysfunction is characterized by a disturbance in the
processes that are involved in the sexual response cycle or by pain
associated with sexual intercourse. The sexual response cycle
comprises the four phases of desire, excitement, orgasm and
resolution. Disorders of sexual response may occur at one or more
of these phases. The sexual dysfunctions include sexual desire
disorders, sexual arousal disorders, orgasmic disorders and sexual
pain disorders. Sexual dysfunctions cause marked distress and
interpersonal difficulty. While progress has been made in the
treatment of such disorders, there remains significant need for
alternative therapeutic approaches.
[0004] A normal erection occurs as a result of a coordinated
vascular event in the penis. This is usually triggered neurally and
consists of vasodilation and smooth muscle relaxation in the penis
and its supplying arterial vessels. Arterial inflow causes
enlargement of the substance of the corpora cavernosa. Venous
outflow is trapped by this enlargement, permitting sustained high
blood pressures in the penis sufficient to cause rigidity. Muscles
in the perineum also assist in creating and maintaining penile
rigidity. Erection may be induced centrally in the nervous system
by sexual thoughts or fantasy, and is usually reinforced locally by
reflex mechanisms. Erectile mechanics are substantially similar in
the female for the clitoris. Impotence or male erectile dysfunction
is defined as the inability to achieve and sustain an erection
sufficient for intercourse. Impotence in any given case can result
from psychological disturbances (psychogenic), from physiological
abnormalities in general (organic), from neurological disturbances
(neurogenic), hormonal deficiencies (endocrine) or from a
combination of the foregoing. These descriptions are not exact,
however. There is currently no standardized method of diagnosis or
treatment. As used herein, psychogenic impotence is defined as
functional impotence with no apparent overwhelming organic basis.
It may be characterized by an ability to have an erection in
response to some stimuli (e.g., masturbation, spontaneous
nocturnal, spontaneous early morning, video erotica, etc.) but not
others (e.g., partner or spousal attention). Various methods for
the treatment of impotence have been suggested, including external
devices, for example, tourniquets (see U.S. Pat. No. 2,818,855). In
addition, penile implants, such as hinged or solid rods and
inflatable, spring driven or hydraulic models, have been used for
some time. The administration of erection effecting and enhancing
drugs is taught in U.S. Pat. No. 4,127,118 to LaTorre. That patent
teaches a method of treating male impotence by injecting into the
penis an appropriate vasodilator, in particular, an adrenergic
blocking agent or a smooth muscle relaxant to effect and enhance an
erection. More recently, U.S. Pat. No. 4,801,587 to Voss et al.
teaches the application of an ointment to relieve impotence. The
ointment consists of the vasodilators papaverine, hydralazine,
sodium nitroprusside, phenoxybenzamine, or phentolamine and a
carrier to assist absorption of the primary agent through the skin.
U.S. Pat. No. 5,256,652 to El-Rashidy teaches the use of an aqueous
topical composition of a vasodilator such as papaverine together
with hydroxypropyl-.beta.-cyclodextrin. Sexual functions in females
can be divided into several broad areas: desire, arousal, and
orgasm. Studies have indicated that up to 63% of women exhibit
dysfunctions in either arousal or orgasmic stages of sexual
activities (Frank E, et al., 1978. N Engl J Med 299: 111). Sexual
disorders such as dyspareunia and vaginismus, reduce the arousal
phase of female sexual functioning. Impaired clitoral
responsiveness can lead to orgasmic disorders. The prevalence of
female sexual dysfunction increases with age (Goldstein M and Teng
N. 1991, Clin Geriatr Med 7:41; Thirlaway K et al., 1996. Quality
of Life Res 5:81; Slob A et al., 1990, J Sex Martial Ther 16:59).
Vascular risk factors of coronary diseases also increase the
probability of sexual dysfunction in postmenopausal females
(Sadeghi-Nejad H et al., 1996, J Urol 155:677A). Female sexual
dysfunction can be due to an impairment in endothelium dependent
vasodilation and smooth muscle relaxation which in turn could lead
to impairment of vascular dependent events associated with sexual
functioning. During sexual arousal, an increase in vaginal blood
flow occurs which in turn results in vaginal lengthening and
enhanced production of vaginal fluid. Enhanced clitoral blood flow
occurs during arousal leading to clitoral engorgement and erection.
Impairment of these vascular dependent events can lead to
impairment in vaginal lubrication and/or a diminution in vaginal
enlargement during the arousal stage of female sexual function. An
abnormality in these vascular dependent events could impair the
arousal and/or orgasmic phases of sexual functioning.
SUMMARY OF THE INVENTION
[0005] The present invention provides a unique therapeutic approach
to improving sexual function or the treatment of sexual dysfunction
by what is presently believed to be a mechanism comprising
inhibition of one or more neurogenic peptidases and a consequent
therapeutically beneficial change in the concentrations of multiple
neurologically significant neurotransmitters in the brain.
[0006] The method comprises the step of administering to a mammal
suffering from or disposed to develop sexual dysfunction, or
otherwise in need of enhanced sexual function, a compound which
exhibits specific binding affinity to, and which inhibits function,
of an enzyme selected from a group consisting of .beta.-lactamase,
penicillin-binding protein, and carboxy-peptidase in an amount
effective to promote normal or enhanced sexual function of said
mammal. The compound should possess sufficient blood-brain barrier
transport properties so that blood levels of said compound achieved
by any one of a wide variety of routes of administration, can
provide a concentration of said compound in the central nervous
system of the mammal undergoing treatment effective to improve
sexual function, either by inhibiting the activity of one or more
neurogenic enzymes, for example, carboxy peptidases and/or by
another yet undefined mechanism of action. Treatment is effective
in males, evidenced by enhanced erectile function, and in females
evidenced, for example, by enhanced solicitation behavior.
[0007] In one embodiment of the invention the compound is a
.beta.-lactam ring-containing compound which is capable of
inhibiting the biological activity of a .beta.-lactamase, a
penicillin-binding protein, or a carboxy peptidase such as carboxy
peptidase E. In one embodiment the compound is clavulanic acid or a
pharmaceutically acceptable salt or ester thereof. Other compounds
recognized for their .beta.-lactamase activity, their antibiotic
activity, and/or their ability to inhibit carboxypeptidase E or
other neurologically significant carboxy peptidases and having the
requisite threshold blood-brain barrier transport property can be
employed beneficially in accordance with the present method. Such
compounds can be administered by any one of a wide variety of
art-recognized routes of administration, including but not limited
to oral ingestion, or parenteral, transdermal, inhalation,
sublingual or buccal administration. Dosage ranges depend on the
patient condition/circumstances and the pharmacologically
significant properties of the therapeutic compound including, for
example, minimum inhibitory concentration, absorption, protein
binding, blood-brain barrier transport and the like, and dosage
levels can be determined by extrapolation of effective
concentrations in test animals. Typically the compounds are
administered in accordance with this invention one to four times a
day at a dose of about 0.01 to about 10 mg/kg, about 0.1 to about
10 mg/kg, or up to about 0.2 mg/kg to about 10 mg/kg. Unit dosage
forms can be prepared to contain about 1 mg to about 500 mgs of the
.beta.-lactam compound in combination with a pharmaceutically
acceptable carrier determined typically by the targeted route of
administration. Optionally the .beta.-lactam compound can be
formulated in a prolonged release dosage form from which effective
amounts of the compound are released over a period of about three
hours to about one week or more. Methods for preparing such
controlled release dosage forms are well known in the art and can
be applied to formulate the compounds for use in accordance with
this invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a bar graph showing anxiety scores for clavulanic
acid administered to cotton-top tamarins.
[0009] FIG. 2 is a bar graph showing the effect of clavulanic acid
on sexual arousal in cotton-top tamarins.
[0010] FIG. 3 illustrates several chromatograms from HPLC
electrochemical detection of dialysate samples collected in the
nucleus accumbens in a test animal following intraperitoneal
administration of 10 .mu.g/kg of clavulanic acid. Retention times
for norepinephrine (NE), epinephrine (Epi), dopamine metabolite
DOPAC, dopamine, serotonin metabolite HIAA, serotonin (5-HT), and
homovanillic acid (HVA) are indicated.
[0011] FIGS. 4A and 4B are graphic representations of the
concentrations of neurotransmitters in the nucleus accumbens of a
test animal (AC-1) as a function of time from administration of
clavulanic acid.
[0012] FIG. 4B is similar to FIG. 4A except that it graphical
depicts the relative concentration of serotonin and serotonin
metabolites in the nucleus accumbens as a function of time post
administration of clavulanic acid.
[0013] FIGS. 5A and 5B are similar to FIGS. 4A and 4B but the data
is that from a second test animal (AC-2)
[0014] FIGS. 6A and 6B are similar to FIGS. 4A and 4B except they
depict test data from a third test animal (AC-3)
[0015] FIGS. 7A and 7B are similar to FIGS. 4A and 4B except that
they depict test data from a fourth test animal (AC-4)
[0016] FIGS. 8A and 8B are also similar to FIGS. 4A and 4B except
that they depict test results from a fifth test animal (AC-5).
DETAILED DESCRIPTION OF THE INVENTION
[0017] There is provided in accordance with this invention a method
for improving sexual function in a mammal suffering from or
disposed to develop sexual dysfunction or otherwise in need of
enhanced sexual function to promote normal or enhanced sexual
function. Sexual dysfunction can be the result of any one or a
combination of a wide variety of psychological or physiological
patient conditions. Alternatively, sexual dysfunction can be a
consequence of the temporal/local environment and physiological and
psychological stress imposed by same. It is a condition that
affects not only humans but also non-human mammals such as farm
animals or zoo animals maintained in captivity.
[0018] As used herein, the term "sexual dysfunctions" includes
sexual desire disorders, sexual arousal disorders, orgasmic
disorders, sexual pain disorders, sexual dysfunction due to a
general medical condition, substance-induced sexual dysfunction and
sexual dysfunction not otherwise specified. These sexual
dysfunctions may be further defined by the nature of the onset of
the disorder: either lifelong type or acquired type; by the context
in which the disorder occurs: either generalized type or
situational type; and by the etiological factors associated with
the disorder: either due to psychological factors or due to
combined factors. Specifically, sexual desire disorders include
hypoactive sexual desire disorder and sexual aversion disorder.
Sexual arousal disorders include female sexual arousal disorder and
male erectile disorder. Orgasmic disorders include female orgasmic
disorder, male orgasmic disorder and premature ejaculation. Sexual
pain disorders include dyspareunia and vaginismus. Sexual
dysfunctions due to a general medical condition may result from
neurological conditions (e.g. multiple sclerosis, spinal cord
lesions, neuropathy and temporal lobe lesions), endocrine
conditions (e.g. diabetes melitus, hypothyroidism, hypogonadal
states and pituitary dysfunction), and vascular conditions and
genitourinary conditions (e.g. testicular disease, Peyronie's
disease, urethral infections, postprostatectomy complications,
genital injury or infection, atrophic vaginitis, infections of the
vagina and external genitalia, postsurgical complications such as
episiotomy scars, shortened vagina, cystitis, endometriosis,
uterine prolapse, pelvic infections and neoplasms).
Substance-induced sexual dysfunction can occur in association with
intoxication with the following classes of substance: alcohol;
amphetamine (and amphetamine-like substances); cocaine; opioids;
sedatives, hypnotic and anxiolytics; and other unknown substances.
A decrease in sexual interest and orgasmic disorders may also be
caused by prescribed medication including antihypertensives,
histamine H.sub.2-receptor antagonists, antidepressants,
neuroleptics, anxiolytics, anabolic steroids, and antiepileptics.
Painful orgasm has been reported with fluphenazine, thioridazine
and amoxapine. Priapism has been reported with the use of
chlorpromazine, trazodone and clozapine, and following penile
injections of papaverine or prostaglandin Selective serotonin
reuptake inhibitors may cause decreased sexual desire or arousal
disorders.
[0019] Also, as used herein, the term "sexual dysfunctions"
includes any of the aforementioned sexual dysfunctions, including
loss of libido, resulting from other medical conditions, most
especially resulting from depression and/or anxiety. As used
herein, the term "treatment" refers both to the treatment to
promote normal or enhanced sexual function and to the prevention or
prophylactic therapy of the aforementioned conditions.
[0020] In a related aspect of the invention it has been found that
administration of .beta.-lactamase inhibitors and other compounds
capable of inhibiting penicillin-binding protein and structurally
related mammalian enzymes activate serotonin and/or dopamine
neurotransmission in the brain. Thus in accordance with another
embodiment of the invention there is provided a method of
activating serotonin and/or dopamine neurotransmission in the brain
of a mammal. The method comprises the step of administering to said
mammal a serotonin and/or dopamine neurotransmission enhancing
amount of a compound selected from a .beta.-lactamase inhibitor, a
penicillin sulfoxide, a penicillin sulfone, and a cephalosporin or
a cephalosporin analog or derivative of the formula
##STR00001##
[0021] wherein X is S, SO, SO.sub.2'O, CR.sub.2, R.sub.3, wherein
R.sub.2 and R.sub.3 are independently hydrogen or C.sub.1-C.sub.4
alkyl, R is hydrogen, a salt forming group or an active ester
fanning group; R.sup.1 is hydrogen or C.sub.1-C.sub.4 alkoxy, T is
C.sub.1-C.sub.4 alkyl, halo (including chloro, fluoro, bromo and
iodo), hydroxy, O(C.sub.1-C.sub.4) alkyl, or --CH.sub.2B wherein B
is the residue of a nucleophile B:H, and acyl is the residue of an
organic acid Acyl OH.
[0022] In still another related aspect of the invention there is
provided a method for using such compounds for the preparation of
pharmaceutical formulations useful for activating serotonin and/or
dopamine neurotransmission in the brain. Such formulations are
expected to be effective in the treatment of numerous disease
states having a neurological dysfunction etiology. Such disease
states include but are not limited to addiction, obesity, and
schizophrenia.
[0023] In still one other embodiment of the invention there is
provided a method for improving sexual function in a mammal
suffering from or disposed to develop sexual dysfunction or
otherwise in need of enhanced sexual function. The method comprises
the step of administering to said mammal a compound selected from
the group consisting of a .beta.-lactamase inhibitor, a penicillin,
a penicillin sulfoxide, a penicillin sulfone, and a cephalosporin
or a cephalosporin analog of the formula
##STR00002##
[0024] wherein X is S, SO, SO.sub.2'O, CR.sub.2, R.sub.3, wherein
R.sub.2 and R.sub.3 are independently hydrogen or C.sub.1-C.sub.4
alkyl, R is hydrogen, a salt fanning group or an active ester
forming group; R.sup.1 is hydrogen or C.sub.1-C.sub.4 alkoxy, T is
C.sub.1-C.sub.4 alkyl, halo (including chloro, fluoro, bromo and
iodo), hydroxy, O(C.sub.1-C.sub.4) alkyl, or --CH.sub.2B wherein B
is the residue of a nucleophile B:H, and acyl is the residue of an
organic acid Acyl OH.
[0025] The method can be utilized in both male and female patients
and is preferably carried out with compounds as specified that are
without clinically significant antimicrobial activity, more
preferably compounds that are substantially devoid of antimicrobial
activity.
[0026] One group of compounds useful in accordance with the present
invention are .beta.-lactamase inhibitors. There are many compounds
that are reported in the literature to exhibit the capacity to
inhibit bacterial .beta.-lactamase activity. Such is typically
measured by the compound's ability to inhibit the rate of
hydrolysis of a penicillin or cephalosporin substrate by 50%,
either with or without preincubation. Techniques for assessing or
assaying .beta.-lactamase inhibition and inhibition of other enzyme
activity are well known in the art.
[0027] Most known .beta.-lactamase inhibitors are compounds which
themselves comprise a .beta.-lactamase ring structure. Both the
patent and non-patent art are replete with reference to such
compounds, their preparation, and their mechanism of action.
Inhibition of bacterial .beta.-lactamase can occur either by an
irreversible mechanism or via a reversible mechanism involving a
transient inhibited intermediate in which the .beta.-lactamase
inhibitor binds to and thus blocks the active site on the
.beta.-lactamase molecule. .beta.-lactamases can be inhibited
irreversibly by a .beta.-lactamase inhibitor which competitively or
preferentially binds to the active site on the .beta.-lactamase
molecule where it effectively acylates the .beta.-lactamase as a
first step in deactivating the enzyme.
[0028] Exemplary of known .beta.-lactamase inhibitors in commercial
use are clavulanic acid, sulbactam, and tazobactam. Other known
.beta.-lactamase inhibitors include derivatives or analogs of
clavulanic acid including deoxyclavulanic acid, isoclavulanic acid,
9-deoxyclavulanic acid, 9-amino deoxyclavulanic acid, and other
clavulanic acid derivatives such as those wherein the 9-hydroxy
group has been chemically modified (e.g. as an acetate, n-methyl
carbamate, methyl ether, benzyl ether, or thiomethyl ether).
Sulbactam has been used to prepare prodrugs, for example,
sultamacillin which is absorbed from the gastrointestinal tract and
then hydrolyzed into sulbactam and ampicillin. Other known
.beta.-lactam containing compounds known to possess
.beta.-lactamase inhibitor properties include olivanic acids and
thienamycin of the carbapenem family of novel naturally occurring
.beta.-lactam antibiotics and sultamicillin and aztreonam.
[0029] One preferred .beta.-lactamase inhibitor for use in
accordance with the present invention is clavulanic acid. It has
only weak, though broad spectrum antibacterial activity, and it has
a long record of safe use as a .beta.-lactamase inhibitor in
commercially available combinations with amoxycillin and
ticarcillin. Moreover, it exhibits good oral adsorption and
transport across the blood-brain barrier into the cerebral spinal
fluid. .beta.-lactamase inhibitors can be administered in
accordance with this invention as their pharmaceutically acceptable
salts or as bioactive esters which hydrolyze to provide therapeutic
concentrations of the .beta.-lactamase inhibitor upon patient
administration.
[0030] Effective dosages of the .beta.-lactamase inhibitors when
used in accordance with the method of this invention depends on
patient condition and the method of administration. Animal tests
indicate that clavulanic acid is effective when administered
intraperitoneally at a dose of about 1 .mu.g/kg to about 50
.mu.g/kg. Parenteral doses of .beta.-lactamase inhibitors when used
in accordance with this invention range from about 0.02 to about 20
mg/kg. Oral dosage levels are typically higher, ranging from about
0.05 mg/kg to about 50 mg/kg. The dosage levels can be adjusted
higher or lower by the attending physician depending on patient
condition and the observed clinical response to the initial dosage.
Treatment in accordance with this invention typically includes one
to four daily doses of .beta.-lactamase inhibitor. Formulation of
the inhibitor into controlled release dosage forms (either for
parenteral or oral use) enables effective once or twice a day
dosage protocols.
[0031] In addition to .beta.-lactamase inhibitors, other
.beta.-lactam-containing compounds, i.e., compounds having a
.beta.-lactam ring system, can be used in accordance with this
invention, generally to activate or enhance serotonin and dopamine
neurotransmission, and more specifically to improve sexual function
or to treat certain other disease states responsive to activation
of serotonin and dopamine neurotransmission.
[0032] Examples of such compounds are .beta.-lactam antibiotics,
such as penicillins and cephalosporins and derivatives, for
example, their sulfoxides or sulfones, and analogs thereof, such as
the art recognized 1-oxa-1-dethiacephems and the
1-carba-1-dethiacephems. The prior art is replete with reference to
many of such compounds and their method of
synthesis/preparation.
[0033] Penicillin sulfoxides or sulfones useful in this invention
are of the general formula
##STR00003##
[0034] wherein X is SO or SO.sub.2 and R and Acyl are as defined
above.
[0035] The cephalosporin/cephalosporin analogs/derivatives useful
in accordance with this invention include both 2-cephem compounds
of the formula
##STR00004##
and 3-cephem compounds of the formula
##STR00005##
wherein X is S, SO, SO.sub.2'O, CR.sub.2, R.sub.3, wherein R.sub.2
and R.sub.3 are independently hydrogen or C.sub.1-C.sub.4 alkyl, R
is hydrogen, a salt forming group or an active ester forming group;
R.sup.1 is hydrogen or C.sub.1-C.sub.4 alkoxy, T is C.sub.1-C.sub.4
alkyl, halo (including chloro, fluoro, bromo and iodo), hydroxy,
O(C.sub.1-C.sub.4) alkyl, or --CH.sub.2B wherein B is the residue
of a nucleophile B:H, and Acyl is the residue of an organic acid
Acyl OH.
[0036] Variations of substituents "Acyl," "R.sup.1" and "T" have
been the subject of years of cephalosporin research which produced
many commercially significant cephalosporin antibiotics. While the
nature of such substituent can impact the biological activity of
the respective compounds, the nature of such substituents is not
the focus of the present invention.
[0037] One group of compounds for neurotherapeutic use herein are
.beta.-lactam antibiotics including penicillins, cephalosporins and
monocyclic and bicyclic analogs or derivatives thereof.
Commercially available antibiotics for use in the present method
and use include penams, cephems, 1-oxa-1-dethia cephems, clavams,
clavems, azetidinones, carbapenams, carbapenems and
carbacephems.
[0038] In one embodiment of this invention the .beta.-lactam ring
containing compounds for us in this invention are without
clinically significant antibiotic activity, and ideally, they are
substantially devoid of biological activity. Such compounds
include, for example, the 2-cephem compounds generally and as well
the 2- and 3-cephem sulfoxide (X.dbd.SO) and sulfone derivatives
(S--SO.sub.2) and penicillin sulfoxide and sulfone derivatives.
[0039] The .beta.-lactam compounds for use in this invention having
a carboxylate functional group can be administered as its
pharmaceutically acceptable salt or in the form of an in vivo
hydrolysable (active) ester group.
[0040] Examples of suitable in vivo hydrolysable (active) ester
groups include, for example, acyloxyalkyl groups such as
acetoxymethyl, pivaloyloxymethyl, .beta.-acetoxyethyl,
.beta.-pivaloyloxyethyl, 1-(cyclohexylcarboonyloxy) prop-1-yl, and
(1-aminoethyl) carbonyloxymethyl; alkoxycarbonyloxyalkyl groups,
such as ethoxycarbonyloxymethyl and alpha-ethoxycarbonyloxyethyl;
dialkylaminoalkyl groups, such as ethoxycarbonyloxymethyl and
.beta.-ethoxycarbonyloxyethyl; dialkylaminoalkyl especially
di-lower alkylamino alkyl groups such as dimethylaminomethyl,
dimethylaminoethyl, diethylaminomethyl or
diethylaminoethyl:2-(alkoxycarbonyl)-2-alkenyl groups such as
2-(isobutoxycarbonyl) pent-2-enyl and 2-(ethoxycarbonyl)but-2-enyl;
lactone groups such as phthalidyl and dimethoxyphthalidyl; and
esters linked to a second .beta.-lactam compound.
[0041] Suitable pharmaceutically acceptable salts of .beta.-lactam
compounds used in this invention include metal salts, e.g.
aluminum, alkali metal salts such as sodium or potassium, alkaline
earth metal salts such as calcium or magnesium, and ammonium or
substituted ammonium salts, for example those with lower
alkylamines such as triethylamine, hydroxy-lower alkylamines such
as 2-hydroxyethylamine, bis-(2-hydroxyethyl)amine or
tris-(2-hydroxyethyl)amine, cycloalkylamines such as
dicyclohexylamine, or with procaine, dibenzylamine,
N,N-dibenzylethylenediamine, 1-ephenamine, N-methylmorpholine,
N-ethylpiperidine, N-benzyl-.beta.-phenethylamine,
dehydroabietylamine, N,N'-bisdehydro-abietylamine, ethylenediamine,
or bases of the pyridine type such as pyridine, collidine or
quinoline, or other amines which have been used to form salts with
known penicillins and cephalosporins. Other useful salts include
the lithium salt and silver salt.
[0042] The amount of .beta.-lactam compounds used to form the
pharmaceutical composition is that amount effective to provide upon
delivery by the intended route of administration, an effective
concentration of the compound in neuronal tissue. Typically they
are administered at a dose of about 0.01 mg/kg to about 10 mg/kg.
Parenteral dosage forms typically can contain about 0.5 to about 50
mg/dose or 2- to 3-fold that amount when formulated in a controlled
release parenteral dosage form, while oral dosage fauns can
typically contain about 1 to about 200 mg of the active
compound.
[0043] Compounds for therapy in accordance with this invention be
formulated/combined with one or more pharmaceutically acceptable
carriers and may be administered, for example, orally in such forms
as tablets, capsules, caplets, dispersible powders, granules,
lozenges, mucosal patches, sachets, and the like. In such
formulations a the active compound is combined with a
pharmaceutically acceptable carrier, for example starch, lactose or
trehalose, alone or in combination with one or more formulation
excipients and pressed into tablets or lozenges or filled into
capsules. Optionally, dosage forms intended for oral ingestion
administration such as tablets, caplets or capsules can be
enterically coated to minimize hydrolysis/degradation in the
stomach. In another embodiment the dosage form is formulated for
oral administration, and is formed as a prolonged release dosage
form using art-recognized formulation techniques for release the
compound over a predetermined period of time.
[0044] Topical dosage forms, including transdermal patches,
intranasal and suppository dosage unit formulations containing the
active compound and conventional non-toxic pharmaceutically
acceptable carriers, adjuvants and vehicles adapted for such routes
of administration can also be used.
[0045] The pharmaceutical compositions suitable for injectable use
in accordance with this invention include sterile aqueous solutions
or dispersions and sterile powders or lyopholysates for the
extemporaneous preparation of sterile injectable solutions or
dispersions. The dosage forms must be sterile and it must be stable
under the conditions of manufacture and storage. The carrier for
injectable formulations is typically water but can also include
ethanol, a polyol (for example, glycerol, propylene glycol and
liquid polyethylene glycol), mixtures thereof, and vegetable
oil.
[0046] Parenteral dosage forms useful in accordance with the
present invention can also be formulated as injectable prolonged
release formulations in which the active compound is combined with
one or more natural or synthetic biodegradable or biodispersible
polymers such as carbohydrates, including starches, gums and
etherified or esterified cellulosic derivatives, polyethers,
polyesters, polyvinyl alcohols, gelatins, or alginates. Such dosage
formulations can be prepared for example in the form of microsphere
suspensions, gels, or shaped polymer matrix implants that are
well-known in the art for their function as "depot-type" drug
delivery systems that provide prolonged release of the biologically
active components. Such compositions can be prepared using
art-recognized formulation techniques and designed for any of a
wide variety of drug release profiles.
Screening Clavulanic Acid (CLAV) for Anxiolytic Activity in
Non-Human Primates
[0047] The cotton-top tamarin (Saguinus oedipus) is listed as an
endangered species with only 1-3 thousand remaining in the rain
forests of Colombia. This monkey has a high stress temperament,
making it difficult to breed and rear in captivity (Snowdon et al.,
1985). Captive tamarins have the highest prevalence of
stress-induced colitis and colon cancer of any monkey studied
(Clapp et al., 1988). The stress of captivity contributes to the
onset of inflammatory bowl disease since this condition is
extremely rare in wild populations (Wood et al., 1998; Wood et al.,
2000) and remission occurs when captive monkeys are returned to the
environmental conditions of the natural habitat (Wood et al.,
1995). If orally administered CLAY could reduce anxiety and stress
in these non-human primates there is a strong likelihood the drug
would be effective when tested in humans. Dr. Charles Snowdon,
Department of Psychology, University of Wisconsin at Madison was
enlisted to design a study using tamarins to test the anxiolytic
activity of CLAY. Dr. Snowdon is a world expert in tamarin behavior
with over twenty peer-reviewed publications in the field. Dr.
Snowdon has studied tamarins in the wild (Savage et al., 1997) and
in the semi-natural environment of his labs at Madison (Ginther et
al., 2000).
Methods
[0048] Eight male/female pairs of tamarins with long standing pair
bonds were tested following oral treatments of CLAV and vehicle
(VEH) control. There were no offspring since males were
vasectomized. Both members of a pair received the same treatments
at the same times. Each animal served as its own control being
tested both with CLAV or VEH one week apart. The treatment schedule
was counter-balanced. CLAV was dissolved in water and dispensed
onto a small cookie in a volume of 100 .mu.l. A single CLAV cookie
was given to each member of a pair at an approximate dose of 1
mg/kg body weight. Animals were given three CLAV cookies each day
for two consecutive days. The 1.sup.st cookie was given at 8:00 AM
prior to the morning feeding, the 2.sup.nd at 11:00 AM prior to the
noon feeding and the 3.sup.rd at 2:00 PM prior to the late
afternoon snack. All animals were scored for anti-anxiety activity
60 min after the 3.sup.rd treatment on the second day.
[0049] This treatment regimen of three doses each day for two
consecutive days was chosen to acclimate the animals to the
treatment procedure (day 1) and to achieve steady-state blood
concentration before testing (day 2). A pharmacokinetic assessment
of CLAV was run by IVEDCO (Irving Tex.) which estimated an oral
dose of 1 mg/kg every three hrs would produce steady-state levels
yielding an average plasma concentration of 2.5 .mu.g/ml at the
time of testing. Since the CSF/plasma ratio is 0.25 the estimated
concentration in the brain would be around 0.3 .mu.M. Given the
rate of clearance of CLAV, treatments from day 1 should not have
contributed to blood levels of drug on day 2.
[0050] Two observers blind to the treatment independently scored
behavioral activity. To elicit anxious/stressful behavior a novel
object was placed into the home cage. A different novel object was
used for each test session and the object presentation was
counter-balanced. Following the presentation of the novel object
animals were scored for a duration of 15 min for: 1) latency to
approach and latency to touch the object, 2) time spent in contact
or proximity with the object, 3) face and head movement (frowns,
head shakes and head cocks that reflect tension), 4) scratching (a
validated measure of anxiety in macaques), 5) piloerection
(autonomic stress response), and 6) visual scanning (nervous
vigilance). On the first test session, it was noted that males
treated with CLAV showed a high incidence of penile erection, hence
the number of erections; mounts and female solicitations were also
scored.
Results
[0051] There was no significant difference between treatments in
latency to approach or latency to touch the novel object. Neither
was there any difference in time spent in proximity to the object.
However, using the combined measures of anxious/nervous behaviors
(3, 4, 5 & 6) there were significantly fewer of these behaviors
following treatment with CLAV (12.7+4.8) than with VEH (16.8=6.4)
(Wilcoxon t=28, n=15 p<0.05) (FIG. 1). There were no gender
differences in drug response.
[0052] The unexpected result was the increase in erections by
males. All eight males showed at least one erection in 15 min when
treated with CLAV while only three of these eight showed erections
with VEH (FIG. 2). The mean was 2.25 erections in 15 min with CLAV
and 0.37 with VEH. Cotton-top tamarins in captivity show an average
base rate of 1.5 erections per hour during their active diurnal
period, a rate comparable to VEH treatment (Snowdon personal
communication). Animals treated with CLAV show a rate of 9.0
erections per hour. These results were significant by a Wilcoxon
test (t=0, n=7, p<0.02). Two of the eight females showed
solicitation behaviors with CLAV treatment while no females showed
solicitation with VEH. There was no significant difference in
mounting behavior between CLAV and VEH treatments.
Summary
[0053] Clavulanic acid given orally at a dose of 1 mg/kg reduced
measures of anxiety in male/female pairs of cotton-top tamarins.
The time course of action was very rapid and appeared in less than
two days of treatments. It is possible the effect could have been
observed in 60 min after a single dose of CLAV, as is the case in
rodent studies. Studies are presently underway to ascertain the
minimal oral dose of CLAV and the shortest time course that
significantly reduces anxiety in tamarins. Nonetheless, the
time-course noted in these studies is far better than the selective
serotonin reuptake inhibitors (SSRIs), e.g., fluoxetine and
sertraline that are becoming more prevalent in the treatment of
anxiety disorders. SSRIs take several days to weeks before
achieving clinical efficacy. In addition, the SSRIs suppress libido
contributing to sexual dysfunction (Rothschild 2000). CLAV not only
reduced anxiety in cotton-top tamarins, but it also increased
sexual arousal as indicated by the increased rate of penile
erections. The mechanism for this biological effect is unknown.
CLAV could have a direct psychogenic effect on libido or the
enhanced sexual arousal could be secondary to a reduction in
stress. The latter hypothesis is not unreasonable since stress is
one of the major factors contributing to sexual dysfunction (Smith
1988). The anxiety disorder, PTSD or post-traumatic stress disorder
has a particularly high incidence of sexual dysfunction (Kotler et
al., 2000). Studies in rats show that long-term psychological
stress impairs sexual behavior, a result associated with a decrease
in monoamine activity in the brain (Sato et al., 1996). Enhancing
monoamine activity restores normal sexual behavior following
chronic stress. It was determined to gather data to assess whether
CLAV is increasing sexual arousal in tamarins by increasing
monoamine activity in the brain.
[0054] Using CLAV to reduce anxiety and enhance sexual arousal in
the cotton-top tamarin, a species whose existence is jeopardized by
its high stress temperament, is very significant. This drug may
have a role in animal husbandry to help in the breeding and rearing
of endangered species held in captivity. More importantly, the fact
CLAV has anxiolytic activity in the tamarin holds the promise the
CLAY and other .beta.-lactamase inhibitors and other .beta.-lactam
compounds may be an effective therapeutic for the treatment of
anxiety disorders in humans and even stress-related
gastrointestinal disease.
[0055] While CLAY does not appear to bind to any of the well known
signaling receptors or transporters, is clearly altering brain
chemistry in some way, either by neurogenic enzyme inhibition or by
interaction with a still unrecognized receptor system, to achieve
anxiolytic activity. To test this hypothesis, extracellular
neurotransmitter levels in the area of the nucleus accumbens were
assessed with microdialysis following CLAY treatment. The accumbens
is part of the limbic forebrain best know for its association with
the pathophysiology of schizophrenia and drug addiction but also
thought to be involved in sensitization to early life trauma
leading to the anxiety disorder PTSD or post traumatic stress
disorder (Charney and Bremner 1999).
Experimental Procedure
[0056] Ten male, Sprague Dawley rats were anesthetized with sodium
pentobarbital (50 mg/kg) and implanted with a unilateral
microdialysis guide cannula aimed at the nucleus accumbens. Two
days after recovery from surgery a microdialysis probe (2 mm) was
lowered to the area and connected to an infusion pump through Tygon
tubing. The dialysate was artificial CSF at pH 7.4 delivered at a
flow rate of 2*l/min. The first 120 min of dialysate will be
discarded. Thereafter, samples were collected at 30 min intervals
prior to and following IP CLAV treatment (10*g/kg). Samples were
collected into microfuge tubes containing 5*l of 0.16 N perchloric
acid to stabilize catecholamines. At the end of the study, animals
were sacrificed and the brains prepared for histology to verify the
site of the microdialysis probe.
Results
[0057] Five of the ten animals studied showed the microdialysis
probe positioned in the nucleus accumbens (AC). In these five
animals (AC-1 through AC-5), electrochemical detection revealed a
time-dependent change in molecules associated with enhanced
neurotransmission of the serotonin and dopamine systems (FIGS. 4A,
B-8A, B). For example, FIG. 4A is a composite of chromatograms
showing changes in monoaminergic molecules prior to and following
CLAV treatment in animals AC-1. Over time there is an increase in
extracellular levels of serotonin concomitant with a robust
increase in the serotonin metabolite 5-hydroxyindoleacetic acid
(HIAA). While there is a modest decrease in dopamine there is a
robust increase in its metabolites homovanillic acid (HVA) and
3,4-dihydroxyphenylacetic acid (DOPAC). These increases in
metabolite levels most probably reflect increased neurotransmission
of serotonin and dopamine. However, it is possible that some of the
metabolism is not directly coupled to the release of the
neurotransmitters (Westernick, 1985).
[0058] The percent change from control values for these
monoaminergic molecules for animals AC-1 through AC-5 are shown in
FIGS. 4A, B-8A, B, respectively. The change in serotoninergic
molecules was fairly consistent. In all cases, animals showed
increases in the serotonin metabolite HIAA of 100%-1000% above
baseline (30-50 pm/ml) following CLAV treatment. The changes in
serotonin levels were more variable with three cases showing an
increase of 50%-100% above baseline (undetectable--5 pm/ml), one no
change, and the other a modest decrease. The change in dopaminergic
molecules was also fairly consistent. In four of five animals there
was an increase in the major dopamine metabolite HVA of 15%-350%
above baseline (50-105 pm/ml) following CLAV treatment. The
exception, animal AC-5 (FIG. 8B) showed high baseline levels of HVA
that remained stable over the course of the study; however, levels
of the other dopamine metabolite DOPAC rose. In three of five
animals dopamine levels increased 50%-450% above baseline (0.5-0.7
pm/ml) following CLAY treatment, while the other two decreased.
DOPAC levels only rose in two cases AC-3 and AC-5, the same animals
that showed decreases in dopamine.
[0059] Animals with the microdialysis probe outside the nucleus
accumbens showed little if any changes in dopamine and serotonin
neurotransmission following CLAY treatment. These sites were the
lateral ventricle, bed nucleus of stria terminalis, head of the
caudate, and ventrolateral thalamus.
Summary
[0060] These microdialysis studies indicate CLAY increases
serotonin and dopamine neurotransmission in the nucleus accumbens.
Recent advances in the treatment of anxiety disorders have focused
on the activation of the serotonin neurotransmission (Feighner
1999). Given the work in this area it is not surprising that CLAV's
release of serotonin is accompanied by robust anti-anxiety behavior
in animal models. Interestingly, the enhanced monoaminergic
neurotransmission with CLAY treatment may explain, in part, the
increased sexual arousal in the stress-prone cotton-top tamarin
[0061] The activation of serotonin and dopamine neurotransmission
in the nucleus accumbens raises the possibility that CLAY may be
used to treat drug addiction, obesity, and schizophrenia. Work by
scientists at the National Institute of Drug Abuse and the National
Institute of Diabetes and Digestive and Kidney Diseases have shown
that the combined administration of amphetamine analogs phentermine
and fenfluramine (PHEN/FEN) increases extracellular dopamine and
serotonin levels in the nucleus accumbens of rats (Baumann et al.,
2000). PHEN/FEN is a an effective pharmacotherapy for obesity
(Weintraub et al., 1984) and in open clinical trials decreased
cocaine craving, alleviated withdrawal symptoms and prolonged drug
abstinence (Rothman et al., 1994). Scientists at the National
Institutes of Health concluded drugs with a similar mechanism to
PHEN/FEN causing increased neurotransmission of serotonin and
dopamine in the nucleus accumbens may have utility in the treatment
of substance abuse and obesity.
[0062] Work by scientists from Eli Lilly and Company used
microdialysis and ex vivo tissue analysis of prefrontal cortex and
nucleus accumbens to evaluate the mechanism of action of a
metabotropic glutamate receptor agonists being developed for the
treatment of psychosis (Cartmell et al., 2000a; 2000b). Atypical
antipsychotics like risperidone increase dopamine and serotonin
neurotransmission in the prefrontal cortex and nucleus accumbens
(Cartmell et al., 2000b; Hertel et al. 1997). The Lilly scientists
found that activation of metabotropic glutamate receptors has a
similar mechanism elevating DOPAC, HIAA and HVA in these brain
areas.
[0063] How CLAV alters serotonin and dopamine neurotransmission is
still unknown. Neither the monoamine transporters nor the
degradative enzyme monoamine oxidase A show binding to CLAV.
Antagonism of any of these receptor proteins would be expected to
alter extracellular levels of monoaminergic molecules. It would
appear CLAV enhances serotonin and dopamine neurotransmission
indirectly by suppressing or activating other neurotransmitter
systems that regulate their activity. CLAV binding to proteolytic
enzyme systems that regulate glutamate activity in the brain have
been examined.
Pharmaceutical Formulations and Use
[0064] The following formulations are prepared using standard
formulation techniques with a mass ratio of carrier to active
compound of about 99:1 to about 30:1.
TABLE-US-00001 Formulations Dosage .beta.-lactamase inhibitor/dose
(mg) Carrier Form I. Clavulanic acid, potassium/30 starch/maltose
capsule II. Clavulanic acid, sodium/50 microcrystalline tablet
cellulose/trehalose III. Tazobactam/75 saline injectable IV.
Tazobactam/125 starch microspheres injectable V. Clavulanic acid,
potassium/150 saline injectable VI. Sulbactam/200 saline injectable
VII. Sulbactam/250 polylactide injectable microspheres VIII.
Cefsulodin/50 starch microspheres injectable IX. Moxalactam
bis-indanyl ester/20 microcrystalline capsule cellulose X.
Cefazolin/120 saline injectable XI. Cefazolin sulfoxide/10 saline
injectable XII. Cephalexin sulfone/35 polylactic acid injectable
microspheres XIII Cefaclor sulfoxide/75 saline injectable
Formulation Use
[0065] A). A male patient suffering from erectile dysfunction is
administered a dose of Formulation I about 1 hour before conjugal
activity to improve sexual performance.
[0066] B). A female patient suffering from mild depression
self-administers Formulation IX t.i.d. over a 2-week period to
improve her libido.
[0067] C). A dog breeder administers Formulation V to his female
and/or male canines to promote breeding activities.
[0068] D). A zoo keeper administers Formulation XI to male and
female partners of a rare simian species to promote reproductive
breeding of the animals.
* * * * *