NZ624056B2 - Compositions of buprenorphine and mu-opioid receptor antagonists - Google Patents

Abstract

The disclosure relates to a composition comprising buprenorphine and a ? opioid receptor antagonist, wherein the composition is characterized by an Agonist Antagonist Activity Index (AAnAI) of between about 0.75 and about 2.2. The composition may comprise an antagonist of formula I. The composition may be used to treat a depressive disorder. may be used to treat a depressive disorder.

Description

WO 2013088243 Title: COMPOSITIONS OF BUPRENORPHINE AND MU-OPIOID RECEPTOR ANTAGONISTS RELATED APPLICATION This application claims the benefit ofUS. Provisional Application No. ,233, filed on December 15, 2011. The entire teachings of the above application are incorporated herein by nce.

BACKGROUND The opioid neuropeptide system plays an important part in regulating mood disorders.

[Machado-Viera R. et. al., Depression and Anxiety, 28 (4) 2011, 267-281]. Opioid peptides and their receptors are potential ates for the development of novel antidepressant treatment. The actions of endogenous s and s are mediated by three receptor types (u, 5 and K), which are coupled to different intracellular effector systems. [Berrocoso E. et. al., Current Pharmaceutical Design, 15(14) 2009, 1612-22]. As such, agents that can modulate the actions of one or more of the opioid receptor types with ivity and sensitivity are important to treat the various diseases and disorders regulated by the opioid system.

The u—opioid system has a profound effect on emotional state and is ted in the context ofmajor sive disorders (MDD) and changes in emotional state. The u-opioid receptors are present and densely distributed in brain regions implicated in the response to stressors and the regulation and ation of emotionally significant stimuli. These include cortical regions, including the rostral anterior cingulate, prefrontal cortex [Eisenberger, e 302, 2003, 290-2; Kennedy Arch Gen Psychiatry 63(11), 2006, 1199-208; Zubieta, Science, 293 2001 , 311-5; Zubieta, Arch Gen Psychiatry, 60(11), 2003, 1145-53].

Subcortically, the u-opioid system is known to have a prominent regulatory role in the opallidal pathway (nucleus accumbens, ventral pallidum) and associated circuits (e.g., amygdala, thalamus, r cortex) involved in the evaluation and response to salient stimuli, both rewarding and nonrewarding [Anderson AK, and Sobel N. Neuron 39(4) 2003, 581-3; Horvitz JC., Behav ci. 114(5), 2000, 934-9; Koob and Le Alcoholism Clinical & Experimental Research, 2001 25(5 Suppl.) 2001, 144S-151S; Napier and ic, Ann N Y Acad Sci., 1999, 176—201; Price 2000; Quirarte, Brain Res., 808(2), 1998, 134-40.; Steiner WO 88243 and Gerfen, Exp Brain Res., 60-76, 1998; Zubieta, Science, 293 2001, 311-5]. Activation of u-opioid receptors increases dopamine which may contribute to anti-depressant effects including enhancement of hedonic tone and sense of contentment, but will lead also to abuse when the increase in dopamine is higher than required to treat symptoms of sion.

Positron emission tomography (PET) studies in humans have shown functional effects of the u-opioid system in the regulation of mood. In vivo u-opioid receptor availability in the sub-amygdalar temporal cortex has been found to inversely correlate with the metabolic ses of this region to the presentation of a negative emotional challenge [Liberzon, Proc Natl Acad Sci. 99(10): 2002, 7084-9]. In a subsequent PET study emotional challenges were shown to elicit further differences in brain u ty between normal human subjects, patients with SSRI sive MDD, and ts with treatment resistant depression [Kennedy, Curr. Psychiatry Rep. 8(6), 2006, 437-44].

It has been hypothesized that blockade of K-receptor activation will have a beneficial therapeutic effect in the treatment of depression. The esis is based on human and animal evidence generated primarily during the past two decades. The following discussion is adapted from a recent review by Knoll and Carlezon, Jr. [Brain Res. 2010, 56-73, 2010].

Whereas u-opioid receptor tion results in elevation of mood in humans, activation of the K-opioid receptor is associated with adverse effects on mood, including dysphoria and anhedonia [Pfeiffer, Horm Metab Res.,l8(l2): 1986, 842-8].

Anatomically, the K-opioid receptor and dynorphin, the y endogenous K ligand, are expressed throughout limbic brain areas implicated in the pathophysiology of depression.

In addition to dysphoria and anhedonia, some aspects of the aversive effects of K activation appear to involve increased anxiety. K-opioid receptors and dynorphin are sed throughout brain areas involved in fear and anxiety, including the amygdala and ed amygdala (Alheid 2003; Fallon and Leslie 1986; Mansour, 1995b]. The effect of K blockade in humans has yet to be tested in ; a ceutically acceptable probe has eluded medicinal chemistry efforts.

Treatment resistant depression (TRD), a widespread disease where patients with MDD do not achieve an adequate response to monoamine reuptake inhibitor epressant therapy. Despite the emergence of le new therapeutic agents in recent decades, TRD remains a major clinical and public health m that results in significant adverse consequences to patients, families, and society as a whole [Gibson, J., Manag. Care, 16:370- 377, 2010; Sackeim, J Clin atry, 62 Suppl 16:10-17, 2001]. Prior to the advent of monoamine oxidase inhibitors (MAOIs) and tricyclic antidepressants , opioids were the primary therapeutic modality for depression. Modern characterization of the endogenous opioid system has elaborated the role of opioidergic peptides in the regulation of both stress response behaviors and hedonic tone. Buprenorphine, a partial u-opioid agonist, has been reported to be useful in treating sion in patients where other available therapies have failed. [Callaway, Soc. Biol. Psychiatry, 39, 1996, 989-990; Emrich et. al., harmacology, 22, 1983, 385-388; Bodkin et. al., J. Clin. Psychopharmacology, 15, 49- 57, 1995].

While opioid ts have anti-depressant effects they are generally not used to treat depression. erm use of a full u-opioid agonist may result in the development of opioid- ency in patients. In addition there are other undesirable side effects including additive potential, sedation, respiratory depression, nausea and constipation that will accompany acute and chronic opioid use. Buprenorphine is an u-opioid partial agonist which es typical u-opioid agonist effects and side effects such as additive potential and respiratory depression while producing maximal effects that are less than those of filll agonists like heroin and methadone. Buprenorphine es suff1cient u-agonist effect to enable opioid-addicted individuals to discontinue the misuse of opioids without experiencing withdrawal ms.

While there are many well-known opioid receptor binding compounds, there is little evidence to guide the management of depression that has not responded to a course of antidepressants. Treatment-refractory depression is an important public health problem and large tic trials are needed to inform clinical practice. [Stimpson et al. The British l of Psychiatry, (2002) 181: 4]. There still s a need to develop effective treatments ofmood disorders, in particular major depressive disorders.

SUMMARY OF THE INVENTION The invention relates to a composition comprising buprenorphine and a u opioid receptor antagonist wherein the composition is characterized by an Agonist:Antagonist Activity Index (AAnAI) of between about 0.70 and about 2.2; wherein; [€:n.a!{EL"P)ffi ___ A: s.' é E-Eli ] 955mm" —-. ‘ smmmmsrmfr; .4” ‘ ~55} ] wherein, EC50 represents the half maximal ive serum concentration of buprenorphine, expressed as nM; IC50 represents the half maximal inhibitory concentration of the u opioid antagonist in humans, expressed as nM; CmaX(BUp) represents the peak serum or plasma concentration ofbuprenorphine and/or a u opioid receptor agonist metabolite of buprenorphine, expressed as nM; and NTAGONIST) represents the peak serum tration of the u opioid antagonist and/or a u opioid receptor nist metabolite of said u opioid antagonist, expressed as nM.

The invention fiarther relates to the treatment of depression comprising stering a composition according to the invention to a subject in need thereof.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

Efflux of dopamine in nucleus ens shell after administration of buprenorphine at 0.001 mg/kg, 0.01 mg/kg, 01 mg/kg and 1 mg/kg doses after subcutaneous (SC) administration.

Average dopamine efflux following (SC) administration of buprenorphine at increasing doses.

Reduction in the efflux of dopamine in nucleus accumbens shell following stration of Compound-l naltrexone and nalmefene with , Compound-10, Buprenorphine (0.1 mg/kg).

Log Activity Index (Log AAnAI) versus dopamine efflux for nd-l, Compound-10, xone and nalmefene with Buprenorphine (0.1 mg/kg).

Increase in immobility following sed concentrations of Compound-l in forced swim test in WKY rats treated with orphine (0.1 mg/kg).

The effect of Compound-l on dopamine efflux in WKY rats undergoing forced swim test after treatment with Buprenorphine (0.1 mg/kg).

The efflux of Compound-l on 5-Hydroxyindoleacetic acid (5-HIAA) release in WKY rats undergoing the forced swim test after ent with Buprenorphine (0.1 mg/kg).

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a ition comprising buprenorphine and another opioid receptor binding compound, wherein the opioid receptor binding compound is a u opioid receptor antagonist, and the ition has an Agonist:Antagonist Activity Index (AAnAI) of between about 0.70 and about 2.2; wherein; [Em-SJGSPWIFH '1 a”J , ? = \uAh 3'" [L nie‘xkANTéflflk‘ISTJ f!4 . , H“. . m“at”; ] wherein, EC50 represents the half maximal effective serum concentration of buprenorphine, expressed as nM; IC50 represents the half maximal inhibitory concentration of the u opioid nist in humans, expressed as nM; CmaX(BUp) represents the peak serum or plasma concentration ofbuprenorphine and/or a u opioid receptor agonist metabolite of buprenorphine, expressed as nM; and Cmax(ANTAGONIST) represents the peak serum concentration of the u opioid nist and/or a u opioid receptor antagonist metabolite of said u opioid nist, expressed as nM.

Buprenorphine (BUP) was studied in combination with varying amounts of an opioid antagonist, Compound-l. This study utilized two ratios of the u opioid receptor nist Compound-l and buprenorphine, with the ratios defined by the amount of each drug (in mg) administered: a) 1:8 and b) 1:1 to evaluate safety and tolerability in patients. The 1:8 (Compoundl-BUP) did show an anti-depressive effect however that change from placebo was not statistically significant. The 1:1 ratio not only proved to be better tolerated, but unexpectedly also provided a clear improvement (statistically significant and clinically meaningful versus placebo) in depression over the duration of this trial. While not wanting to be held to any particular theory, it had been thought that at the lower ratio (1 :8) greater u agonist activity would yield greater improvement in anti-depressive effects. It was an unexpected finding that less u activity as exemplified by the higher ratio (1 :1), was not only te to exert an anti-depressive effect, but the effects were greater than that ed with the 1:8 ratio. While the ratios above were based on mass of drug delivered, when the molecular pharmacology, systemic concentrations achieved (a on of bioavailability by the intended route and clearance) and the relative degree of t:antagonist ty was evaluated it was clear that a net opioid agonist activity was present at both the 1:8 and 1:1 . This approach allowed for the determination of the preferred degree of balance between agonist and antagonist activity for the manifestation of an anti-depressive while eliminating the undesired effects, for example, the high associated with the addictive potential of opioids. The 1:8 ratio of Compound-1 :BUP did not result in a statistical or clinically meaningful ement in sion, and at this ratio patients still ed a “high” and sedation; the calculated “agonist:antagonist activity index” (AAnAI) was 13.4. In contrast, for the 1:1 ratio the AAnAI was 1.3. As used herein, the term “addictive potential” refers to the current Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) definition for substance dependence, defined as: the ability for a compound or substance to illicit physiological dependence, evidence of tolerance or awal. Without being bound to any particular , it is believed that to achieve the desired anti-depressive effect the preferred AAnAI is between the values of about 0.5 and 5.0, preferably about 0.7 and about 2.2. In one embodiment, the AAnAI is between about 0.6 and 4.0. In one ment, the AAnAI is between about 0.7 and 3.0. In a preferred embodiment, the AAnAI is between about 0.8 and about 2.1, preferably between about 1.0 and about 2.0, preferably between about 1.0 and about 1.8, preferably between about 1.1 and about 1.6, preferably between about 1.2 and about 1.4, most preferably about 1.3.

An AAnAI can be determined for buprenorphine and any nd characterized as a u receptor antagonist. The following information is required for the u receptor antagonist: l) IC50 based on GTPyS assay; and 2) Cmax concentration ing dosing. For buprenorphine the following are ed: 1) EC50 based on GTPyS assay; and 2) Cmax concentrations following dosing. Other fianctional assays could also be used based on cAMP or other downstream end-points following receptor activation; however the GTPyS is the preferred approach. The dose ng a Cmax value for buprenorphine or the u opioid receptor antagonist may vary with the route of administration. Since the AAnAI is based on Cmax it can be calculated for any route of administration for the combination. Thus AAnAI is the ratio between the activities of buprenorphine and a u receptor antagonist as shown below: [Smart-Siffiiffifl“5“] games = [finmxiawrssnmsrjifr" £51:- ] The EC50 and IC50 values for orphine (BUP) and Compound-l are shown in Table-l below. These values were determined using the GTPyS functional assay.

Table l Buprenorphine Compound-1 Plasma concentrations of buprenorphine and Compound-l were determined in ts following the different dosing paradigms. (Table 2) The Cmax values are reported below for each drug. Cmax values are typically reported as mass/mL. These parameters reflect the potency of the buprenorphine and the u opioid receptor antagonist.

Table 2 Drug Dose Observed nM at Cmax CmaX/IC or (mg) Cmax ) EC50 Compound-1 0.5 BUP 4 Compound-l Cmax ranges from 3.7 to 77X its IC50 value for inhibiting the u opioid receptor, while the buprenorphine Cmax ranges from about 57-99X its EC50 as a partial agonist. At the lower ratio (1:8) the l u agonist activity would dominate. While at the higher ratio (1 : l) theu signaling would be greatly diminished. This agrees well with the observed clinical data. It also establishes the desired ratio that would be required for any u antagonist in combination with BUP to treat depression while eliminating “high” and development of dependency. The desired range for this ratio, defined here as the AAnAI, would be about 0.5 to about 5 for any drug displaying antagonist ty at the u receptor, including Compound-l, naltrexone and nalmefene. At these ratios u signaling adequate to exert an anti-depressive effect, without the t experiencing signs of being ated with the addictive potential of opioids, in particular buprenorphine.

The AAnAI can be calculated for any u opioid antagonist. Naltrexone and ene are two common u opioid antagonists. In the example below, the AAnAI for naltrexone is shown for a range of Cmax values based on a dose of orphine of 8 mg. Since the functional IC50 value is 4.8 nM for naltrexone, higher Cmax values are required to achieve the same AAnAI as with Compound-l. (Table 3) Estimated dose range of naltrexone would be between 350 and 1050 mg to cover ratios of the “BUP agonist:antagonist activity” ratio of between 1 and 2.

Table 3 Dru cm M11 cm nM Cmax/ICSO naltrexone 10 29 50 146 586 122 I_ In addition to differences in potency of antagonists, the ADME (Absorption, Distribution, Metabolism and ion) properties of the compound illustrate why a simple ratio based on the administered dose cannot be used to predict the y of the combination of buprenorphine and an opioid antagonist to treat depression. Again using naltrexone as the example, plasma concentrations achieved with a 50 mg dose of naltrexone are illustrated. The Cmax for naltrexone is approximately 10 ng/mL. Naltrexone displays fairly roportional pharmacokinetics. Consequently, the oral dose of naltrexone needed to achieve the desired AAnAI would be between about 350 and 750 mg. Importantly, to achieve the same AAnAI shown to have a clear clinical benefit for the buprenorphine-Compound-l ation, the dose of naltrexone required would be about 625 mg and the simple ratio based on oral dose would be almost 80:1.

Similar ations can be made for nalmefene (Table 4) based on published literature values for the IC50 (13 nM) and ed plasma concentrations following oral administration. Based on the available literature to achieve the desired AAnAI, plasma concentrations of about 210 to 400 ng/mL are required .

Table 4 Drug AAnAI Nalmefene . 17.8 l .5 l . l The IC50 for nalmefene was determined using the methods described herein and found to be more potent than previously described in the literature. The AAnAI values based on an IC50 of 2.2 nM are provided below in Table 4A.

Table 4A Drug AAnAI ene . . . 12.0 . 37 . 6.0 0.75 0.38 In some ments, the administration of an antagonist resulting in an AAnAI of between about 0.5 to about 5.0, preferably between about 0.7 to 2.2, modulates dopamine release. In one embodiment, the administration of a ation of buprenorphine and an antagonist of the ion results in a decrease in the production of dopamine in the nucleus accumbens shell in comparison with stration of buprenorphine alone. In a preferred embodiment, the administration of a combination of buprenorphine and Compound-l having an activity index of n about 0.7 and about 2.2 results in a reduction in the dopamine release compared to the administration of buprenorphine alone. In a preferred embodiment, the combination of buprenorphine and an antagonist of the invention results in an average dopamine level of n about 1 pg/sample to about 2 pg/sample whereas the administration of buprenorphine alone (0.1 mg/kg) results in about 3 pg/sample after 2 hours.

In one embodiment, the combination of buprenorphine and an antagonist of the invention, having an AAnAI of between about 0.7 to about 2.2, results in a reduction in dopamine release of between about 25% to about 75% in comparison with the administration of buprenorphine alone in a stimulated dopamine efflux test. Without being bound to any ular theory, the reduction in ne release is postulated to be useful in reducing the drug liking and addictive potential of buprenorphine, while retaining properties that contribute to an anti-depressive effect. Importantly, attenuation of u-opioid signaling further by achieving an AAnAI of less than 0.5 would be undesirable with a loss of anti-depressive effect.

In a preferred embodiment, theu opioid receptor antagonist is a compound of Formula Formula I, or a pharmaceutically acceptable salt, ester or g thereof wherein; s is 0, l or 2; tis 0, l, 2, 3, 4, 5, 6, or 7; X is S or 0; R1 is selected from aliphatic, substituted tic, aryl, substituted aryl, heterocyclyl or substituted heterocyclyl; each R2, R3, R4, R5, R6, R7 and R8 is independently selected from absent, hydrogen, halogen, -OR20, -SR20, 21, -C(O)R20, -C(O)OR20, -C(O)NR20R21, - N(R20)C(O)R21, -CF3, -CN, -N02, -N3, acyl, alkoxy, substituted , alkylamino, substituted alkylamino, dialkylamino, substituted dialkylamino, substituted or unsubstituted alkylthio, tuted or unsubstituted alkylsulfonyl, optionally substituted aliphatic, optionally substituted aryl, heterocyclyl or substituted heterocyclyl; each R9 and R10 is selected from hydrogen, aliphatic, substituted tic, aryl, substituted aryl, heterocyclyl or substituted heterocyclyl; 2012/002900 alternatively, two of R2, R3, R4, R5, R6, R7 and R8 together with the atoms they are attached to form an optionally tuted ring; alternatively R2 and R3 together with the carbon they are attached to form a C=X group; wherein each R20 and R21 is independently selected from absent, hydrogen, halogen, - OH, -SH, -NH2, -CF3, -CN, -N02, -N3, -C(O)OH, -C(O)NH2, acyl, alkoxy, substituted alkoxy, alkylamino, substituted alkylamino, dialkylamino, substituted dialkylamino, substituted or unsubstituted alkylthio, substituted or unsubstituted alkylsulfonyl, aliphatic, tuted aliphatic, aryl or substituted aryl; and alternatively R9 and R10 together with the atom they are attached to form an optionally substituted ring; alternatively two R5 groups, or an R5 and an R6 group, together with the carbon they are attached to form a C=X group.

In a more preferred ment, the u receptor antagonist is a compound of Formula II: Formula II, or a pharmaceutically able salt, ester or prodrug thereof wherein; X is S or 0; R1 is —(CH2)n-C-C3H5, —(CH2)n-C-C4H7s —(CH2)n-C-C5H95 n-CH=CH2 OI' - (CH2)n-CH=C(CH3)2 wherein n and m are independently 0, l, 2 or 3; R6 and R7 are independently H, -OH or together R6 and R7 form an —O- or —S- group; R5 and R11 are independently H, -OH, OCH3 or er R5 and R1 form a =0 or =CH2 group.

In a more preferred embodiment, the n receptor antagonist is selected from: OH N/\2\ NH2 0 H O OH O O OH O O 11 12.

The invention fiarther relates to the treatment of a depressive disorder comprising administering a composition according to the invention to a subject in need thereof. In a preferred embodiment, the depressive disorder is selected from major depressive disorder, chronic depression, severe unipolar recurrent major sive episodes, dysthymic disorder, depressive neurosis and neurotic depression, melancholic depression, atypical depression, reactive depression, treatment resistant depression, seasonal affective disorder and pediatric depression; premenstrual syndrome, premenstrual dysphoric disorder, hot flashes, bipolar disorders or manic sion, bipolar I er, bipolar II disorder and cyclothymic disorder. In a preferred embodiment, the depressive disorder is a major depressive disorder.

In a more preferred embodiment, the depressive disorder is treatment resistant depression.

The invention fiarther s to the treatment of obsessive compulsive disorder, bulimia nervosa, panic disorder, posttraumatic stress disorder (PTSD), premenstrual dysphoric disorder (PMDD), social anxiety disorder and generalized anxiety disorder (GAD).

Definitions Listed below are definitions of various terms used to describe this invention. These definitions apply to the terms as they are used hout this specification and claims, unless ise limited in ic instances, either individually or as part of a larger group.

The term atic group” or atic” refers to a non-aromatic moiety that may be saturated (e.g. single bond) or contain one or more units of unsaturation, e.g., double and/or triple bonds. An aliphatic group may be ht chained, branched or cyclic, n carbon, hydrogen or, optionally, one or more heteroatoms and may be tuted or unsubstituted.

In addition to aliphatic hydrocarbon groups, aliphatic groups include, for example, polyalkoxyalkyls, such as polyalkylene glycols, ines, and polyimines, for example.

Such aliphatic groups may be r substituted. It is understood that tic groups may include alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, and substituted or unsubstituted cycloalkyl groups as described herein.

The term “acyl” refers to a carbonyl substituted with en, alkyl, partially saturated or fully saturated cycloalkyl, partially saturated or fillly saturated heterocycle, aryl, or heteroaryl. For example, acyl includes groups such as (C1-C6) alkanoyl (e.g., formyl, , propionyl, butyryl, valeryl, l, lacetyl, etc.), (C3-C6)cycloalkylcarbonyl (e.g., cyclopropylcarbonyl, cyclobutylcarbonyl, cyclopentylcarbonyl, cyclohexylcarbonyl, etc.), heterocyclic carbonyl (e.g., pyrrolidinylcarbonyl, pyrrolidonecarbonyl, piperidinylcarbonyl, piperazinylcarbonyl, tetrahydrofilranylcarbonyl, etc.), aroyl (e. g., benzoyl) and heteroaroyl (e. g., thiophenylcarbonyl, thiophenylcarbonyl, furanyl carbonyl, furanylcarbonyl, lH-pyrroylcarbonyl, lH-pyrroylcarbonyl, benzo[b]thiophenylcarbonyl, etc.). In addition, the alkyl, cycloalkyl, heterocycle, aryl and heteroaryl portion of the acyl group may be any one of the groups described in the respective definitions. When indicated as being “optionally substituted”, the acyl group may be unsubstituted or optionally substituted with one or more substituents (typically, one to three substituents) independently selected from the group of substituents listed below in the definition for ituted" or the alkyl, cycloalkyl, heterocycle, aryl and heteroaryl portion of the acyl group may be substituted as described above in the preferred and more preferred list of substituents, respectively.

The term “alkyl” is intended to include both branched and straight chain, substituted or unsubstituted saturated aliphatic hydrocarbon radicals/groups having the specified number of s. Preferred alkyl groups comprise about 1 to about 24 carbon atoms (“Cl-€24”).

Other preferred alkyl groups comprise at about 1 to about 8 carbon atoms (“C1-C8”) such as about 1 to about 6 carbon atoms 6”), or such as about 1 to about 3 carbon atoms (“C1- C3”). es of C1-C6 alkyl ls include, but are not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, utyl, n-pentyl, neopentyl and n-hexyl radicals.

The term “alkenyl” refers to linear or ed radicals having at least one - carbon double bond. Such radicals preferably contain from about two to about twenty-four carbon atoms (“CZ-CM”). Other preferred alkenyl radicals are “lower alkenyl” radicals WO 88243 having two to about ten carbon atoms (“Cg-Clo”) such as ethenyl, allyl, propenyl, butenyl and 4-methylbutenyl. Preferred lower alkenyl radicals include 2 to about 6 carbon atoms (“C2- C6”). The terms “alkenyl”, and “lower l”, embrace ls having “cis” and “trans” ations, or alternatively, “E” and “Z” orientations.

The term “alkynyl” refers to linear or branched radicals having at least one carbon- carbon triple bond. Such radicals preferably n from about two to about twenty-four carbon atoms (“Cg-C24”). Other preferred alkynyl radicals are “lower alkynyl” radicals having two to about ten carbon atoms such as propargyl, l-propynyl, 2-propynyl, l-butyne, nyl and l-pentynyl. Preferred lower alkynyl radicals include 2 to about 6 carbon atoms (“C2-C6”).

The term “cycloalkyl” refers to saturated carbocyclic radicals having three to about twelve carbon atoms (“Cg-€12”). The term "cycloalkyl" embraces saturated carbocyclic radicals having three to about twelve carbon atoms. Examples of such radicals include cyclopropyl, cyclobutyl, cyclopentyl and exyl.

The term “cycloalkenyl” refers to partially unsaturated carbocyclic radicals having three to twelve carbon atoms. Cycloalkenyl radicals that are partially unsaturated carbocyclic radicals that contain two double bonds (that may or may not be conjugated) can be called “cycloalkyldienyl”. More preferred lkenyl radicals are “lower cycloalkenyl” radicals having four to about eight carbon atoms. Examples of such radicals include cyclobutenyl, cyclopentenyl and cyclohexenyl.

The term “alkylene,” as used herein, refers to a nt group derived from a straight chain or branched saturated hydrocarbon chain having the specified number of carbons atoms. Examples of alkylene groups e, but are not limited to, ethylene, propylene, butylene, yl-pentylene, and 5-ethyl-hexylene.

The term “alkenylene,” as used herein, denotes a divalent group derived from a straight chain or branched hydrocarbon moiety containing the specified number of carbon atoms having at least one carbon-carbon double bond. Alkenylene groups include, but are not limited to, for example, ethenylene, 2-propenylene, 2-butenylene, l-methylbuten-l- ylene, and the like.

The term “alkynylene,” as used herein, denotes a divalent group derived from a straight chain or branched hydrocarbon moiety containing the ed number of carbon atoms having at least one carbon-carbon triple bond. entative alkynylene groups e, but are not limited to, for example, propynylene, l-butynylene, yl hexynylene, and the like.

The term “alkoxy” refers to linear or branched oxy-containing radicals each having alkyl portions of one to about twenty-four carbon atoms or, preferably, one to about twelve carbon atoms. More preferred alkoxy radicals are “lower alkoxy” radicals having one to about ten carbon atoms and more preferably having one to about eight carbon atoms.

Examples of such radicals include methoxy, , propoxy, butoxy and tert-butoxy.

The term “alkoxyalkyl” refers to alkyl radicals having one or more alkoxy radicals attached to the alkyl radical, that is, to form monoalkoxyalkyl and dialkoxyalkyl radicals.

The term “aryl”, alone or in combination, means an aromatic system containing one, two or three rings wherein such rings may be attached together in a t manner or may be filSGd. The term “aryl” embraces aromatic radicals such as phenyl, naphthyl, tetrahydronaphthyl, indane furanyl, quinazolinyl, pyridyl and biphenyl.

The terms “heterocyclyl”, ocycle” “heterocyclic” or “heterocyclo” refer to saturated, partially unsaturated and unsaturated heteroatom-containing haped radicals, which can also be called “heterocyclyl”, “heterocycloalkenyl” and “heteroaryl” correspondingly, where the heteroatoms may be selected from nitrogen, sulfur and oxygen. es of saturated heterocyclyl radicals include saturated 3 to 6-membered heteromonocyclic group containing 1 to 4 nitrogen atoms (e.g. pyrrolidinyl, imidazolidinyl, piperidino, piperazinyl, etc.); ted 3 to 6-membered heteromonocyclic group containing 1 to 2 oxygen atoms and l to 3 en atoms (e.g. morpholinyl, etc.); saturated 3 to 6- membered heteromonocyclic group containing 1 to 2 sulfur atoms and l to 3 nitrogen atoms (e. g., thiazolidinyl, etc.). Examples of partially unsaturated heterocyclyl radicals include dihydrothiophene, dihydropyran, dihydrofuran and dihydrothiazole. Heterocyclyl radicals may e a pentavalent en, such as in tetrazolium and pyridinium radicals. The term ocycle” also embraces radicals where heterocyclyl radicals are fused with aryl or cycloalkyl radicals. Examples of such fused bicyclic radicals include benzofuran, benzothiophene, and the like.

The term “heteroaryl” refers to rated ic heterocyclyl radicals. Examples of heteroaryl radicals include unsaturated 3 to 6 membered heteromonocyclic group containing 1 to 4 nitrogen atoms, for example, pyrrolyl, pyrrolinyl, imidazolyl, pyrazolyl, pyridyl, pyrimidyl, pyrazinyl, pyridazinyl, triazolyl (e. g., 4H-l,2,4-triazolyl, lH-l,2,3- triazolyl, ,3-triazolyl, etc.) tetrazolyl (e.g. razolyl, 2H-tetrazolyl, etc.), etc.; unsaturated condensed heterocyclyl group containing 1 to 5 nitrogen atoms, for example, indolyl, isoindolyl, indolizinyl, benzimidazolyl, quinolyl, isoquinolyl, indazolyl, riazolyl, tetrazolopyridazinyl (e.g., tetrazolo[l,5-b]pyridazinyl, etc.), etc.; rated 3 to 6-membered heteromonocyclic group containing an oxygen atom, for e, pyranyl, furyl, etc.; unsaturated 3 to 6-membered heteromonocyclic group containing a sulfur atom, for example, thienyl, etc.; unsaturated 3- to ered heteromonocyclic group containing 1 to 2 oxygen atoms and l to 3 nitrogen atoms, for example, oxazolyl, olyl, oxadiazolyl (e.g., l,2,4-oxadiazolyl, l,3,4-oxadiazolyl, l,2,5-oxadiazolyl, etc.) etc.; unsaturated condensed heterocyclyl group containing 1 to 2 oxygen atoms and l to 3 en atoms (e.g. benzoxazolyl, benzoxadiazolyl, etc.); unsaturated 3 to 6-membered heteromonocyclic group containing 1 to 2 sulfur atoms and l to 3 nitrogen atoms, for example, thiazolyl, thiadiazolyl (e.g., l,2,4- thiadiazolyl, l,3,4-thiadiazolyl, l,2,5-thiadiazolyl, etc.) etc.; unsaturated condensed cyclyl group containing 1 to 2 sulfur atoms and l to 3 nitrogen atoms (e. g., benzothiazolyl, benzothiadiazolyl, etc.) and the like.

The term “heterocycloalkyl” refers to heterocyclo-substituted alkyl radicals. More preferred cycloalkyl radicals are "lower heterocycloalkyl" radicals haVing one to six carbon atoms in the heterocyclo radical.

The term thio” refers to radicals containing a linear or branched alkyl radical, of one to about ten carbon atoms attached to a divalent sulfur atom. red alkylthio radicals have alkyl radicals of one to about twenty-four carbon atoms or, preferably, one to about twelve carbon atoms. More preferred alkylthio radicals have alkyl radicals which are "lower alkylthio" radicals haVing one to about ten carbon atoms. Most preferred are alkylthio radicals haVing lower alkyl radicals of one to about eight carbon atoms. Examples of such lower alkylthio radicals include methylthio, ethylthio, propylthio, butylthio and hio.

The terms “aralkyl” or “arylalkyl” refer to aryl-substituted alkyl radicals such as benzyl, diphenylmethyl, triphenylmethyl, ethyl, and diphenylethyl.

The term “aryloxy” refers to aryl radicals attached through an oxygen atom to other radicals.

The terms “aralkoxy” or “arylalkoxy” refer to aralkyl radicals attached through an oxygen atom to other radicals.

The term “aminoalkyl” refers to alkyl radicals substituted with amino radicals.

Preferred aminoalkyl radicals have alkyl radicals haVing about one to about twenty-four carbon atoms or, preferably, one to about twelve carbon atoms. More preferred aminoalkyl radicals are "lower aminoalkyl" that have alkyl radicals having one to about ten carbon atoms. Most preferred are aminoalkyl ls having lower alkyl ls having one to eight carbon atoms. Examples of such radicals include aminomethyl, aminoethyl, and the like.

The term “alkylamino” denotes amino groups which are substituted with one or two alkyl radicals. Preferred alkylamino radicals have alkyl radicals having about one to about twenty carbon atoms or, preferably, one to about twelve carbon atoms. More preferred alkylamino radicals are “lower alkylamino” that have alkyl radicals having one to about ten carbon atoms. Most preferred are alkylamino radicals having lower alkyl radicals having one to about eight carbon atoms. Suitable lower alkylamino may be monosubstituted N- alkylamino or disubstituted N,N—alkylamino, such as N-methylamino, N—ethylamino, N,N— dimethylamino, N,N-diethylamino or the like.

The term ”substituted” refers to the replacement of one or more hydrogen radicals in a given structure with the radical of a specified substituent including, but not limited to: halo, alkyl, alkenyl, alkynyl, aryl, heterocyclyl, thiol, hio, arylthio, alkylthioalkyl, ioalkyl, alkylsulfonyl, alkylsulfonylalkyl, arylsulfonylalkyl, alkoxy, aryloxy, aralkoxy, arbonyl, alkylaminocarbonyl, arylaminocarbonyl, alkoxycarbonyl, aryloxycarbonyl, haloalkyl, amino, trifluoromethyl, cyano, nitro, alkylamino, arylamino, minoalkyl, arylaminoalkyl, aminoalkylamino, hydroxy, alkoxyalkyl, carboxyalkyl, alkoxycarbonylalkyl, aminocarbonylalkyl, acyl, aralkoxycarbonyl, carboxylic acid, sulfonic acid, sulfonyl, onic acid, aryl, heteroaryl, heterocyclic, and aliphatic. It is understood that the substituent may be fiarther tuted.

For simplicity, chemical moieties that are d and referred to throughout can be univalent chemical moieties (e. g., alkyl, aryl, etc.) or multivalent moieties under the appropriate structural circumstances clear to those skilled in the art. For example, an “alkyl” moiety can be referred to a monovalent radical (e.g. CH3-CH2-), or in other instances, a bivalent linking moiety can be “alkyl,” in which case those skilled in the art will understand the alkyl to be a divalent radical (e.g., -CH2-CH2-), which is equivalent to the term “alkylene.” Similarly, in circumstances in which divalent moieties are required and are stated as being “alkoxy”, “alkylamino”, “aryloxy”, “alkylthio”, ‘aryl”, oaryl”, “heterocyclic”, “alkyl” “alkenyl”, “alkynyl”, “aliphatic”, or “cycloalkyl”, those skilled in the art will understand that the terms 3, ECalkylamino3, EC 3) “ , , aryloxy”, “alkylthio , aryl”, oaryl”, “heterocyclic , , “alkenyl”, yl”, “aliphatic”, or “cycloalkyl” refer to the ponding divalent moiety.

WO 88243 The terms “halogen” or “halo” as used herein, refers to an atom selected from fluorine, chlorine, bromine and iodine.

The terms “compound” “drug”, and “prodrug” as used herein all include pharmaceutically acceptable salts, co-crystals, solvates, hydrates, polymorphs, omers, diastereoisomers, racemates and the like of the compounds, drugs and prodrugs having the formulas as set forth herein.

Substituents indicated as attached through variable points of attachments can be attached to any available position on the ring structure.

As used herein, the term “effective amount of the subject compounds,” with respect to the subject method of treatment, refers to an amount of the subject compound which, when delivered as part of desired dose regimen, brings about management of the disease or disorder to clinically acceptable standards. ment” or “treating” refers to an approach for obtaining beneficial or desired clinical results in a patient. For purposes of this invention, beneficial or desired clinical results include, but are not limited to, one or more of the following: alleviation of symptoms, diminishment of extent of a e, stabilization (i.e., not worsening) of a state of disease, ting occurrence or recurrence of disease, delay or slowing of disease progression, amelioration of the disease state, and remission (whether partial or total).

As used herein, the term “major depressive disorder” (MDD) is used as that term is tood in art, and refers to a diagnosis that is guided by diagnostic criteria listed in Diagnostic and Statistical Manual of Mental ers, Fourth Edition (DSM-IV) or ICD-lO, or in similar nomenclatures. ts suffering from “treatment resistant depression” include (1) those who fail to respond to standard doses (i.e., cantly superior to placebo in double-blind studies) of pressants (such as a ine oxidase inhibitors (MAOIs), tricyclic pressants (TCAs), tetracyclic antidepressants (TeCAs), selective serotonin reuptake inhibitors (SSRIs), and serotonin-norepinephrine reuptake tors (SNRIs)) administered continuously for a m duration of 6 weeks, and (2) those who fail to respond to standard doses of an antidepressant (such as a monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCAs), tetracyclic pressants (TeCAs), selective serotonin reuptake tors (SSRIs), and serotonin-norepinephrine reuptake inhibitors (SNRIs)) (monotherapy) administered continuously for a m duration of 12 weeks. One criteria for determining whether a patient's depression is treatment resistant to an antidepressant is if a Clinical Global Impression-Improvement (CGI-I) score of 1 (very much improved) or 2 (much improved) is not achieved by the end of a 6, 8, or 12 week trial. The CGI-I scale is defined in Guy, W. (ed.): ECDEU Assessment Manual for Psychopharmacology, Revised, DHEW Pub. No.

(ADM) 76-338, Rockville, Md., National Institute of Mental Health, 1976.

EXAMPLES Example 1 - A randomized, -blind, placebo-controlled study was conducted evaluating the safety and tolerability of a combination of buprenorphine with Compound-1.

The study was ted in 32 adults with major depressive er who had an inadequate response to antidepressant therapy. In this study, subjects received a once daily sublingual dose of placebo or CompoundBUP at dose ratios of 1 :8 or 1:1 with corresponding escalating doses of mg/0.5:4mg and 4:4mg/8:8mg, respectively, for 7 days.

Among the most common adverse events were dizziness, nausea, vomiting, and sedation (all of which were reported more frequently by subjects in the 1:8 ratio group (Cohort A) versus subjects in the 1:1 ratio (Cohort B) or placebo groups). For example, while about 28.5% of Cohort A ed sedation or somnolence, only 7% of Cohort B reported sedation or somnolence. The occurrence of ess was also significantly higher in Cohort A (57%) compared to Cohort B (29%). A y of the most common adverse events (i.e, those reported by 210% of subjects in any treatment group) is provided in Table Table A: Com arison of most common adverse events >10% in an rou between placebo, Cohort A and Cohort B Adverse Event Placebo Cohort B Preferred Term (N=4) (N=14) —o 857 429 _2s 429 321 —o 429* 214* 1(7) 3 21 somnolence Fati_ue Feeling abnormal Flushing *One subject from each active group discontinued due to vomiting.

Cohort A: 1:8 ratio of Compound 1: Buprenorphine (0.25mg:2mg for days 1 to 3 and 0.5mg:4mg for days 4 to 7) Cohort B: 1:1 ratio of Compound 1: Buprenorphine mg for days 1 to 3 and 8mg:8mg for days 4 to 7 Efficacy was measured by changes from baseline to Day 7 in the 17-item Hamilton Rating Scale for Depression (HAM-D-17) and the mery-Asberg Depression Rating Scale (MADRS). For subjects treated with CompoundBUP at the 1:8 and 1:1 dose ratios or placebo, mean (standard deviation) changes from baseline to day 7 in HAM-D-17 total scores were -5.0 (6.1), -6.7 (3.4), and -1.0 (4.2), respectively (p=0.032 for the 1:1 ratio versus placebo) and mean (SD) s from baseline to day 7 in MADRS total scores were -8.5 (.4), -11.4 (6.6), and -3.5 (5.8), respectively. See Tables B and C.

TABLE B: ison of ent efficacy between placebo, Cohort A and Cohort B assessed by Hamilton Depression Rating Sacle-17 (Total Score) Parameter o Cohort A (1:8) Cohort B (1:1) (PBO) Baseline score # subjects N=4 N=14 N=14 mean (SD) 19.0 (3.2) 17.5 (2.0) 19.4 (2.7) median 18.5 17.5 19.0 Change from # subjects N=4 N=13 N=13 basehne at Day 7 mean (SD) —1.0 (4.2) —5.0 (6.1) -6.7 (3.4) median 0 -4.0 -6.0 Comparison of Cohort A vs. Cohort B vs. changes from PBO PBO baseline -5.69 (3.57) 0.032 p value from exact Wilcoxon test Cohort A: 1:8 ratio of Compound 1: orphine (0.25mg:2mg for days 1 to 3 and 0.5mg:4mg for days 4 to 7) Cohort B: 1:1 ratio of Compound 1: Buprenorphine (4mg:4mg for days 1 to 3 and 8mg:8mg for days 4 to 7 TABLE C: Com arison of treatment efficac between lacebo Cohort A and Cohort B assessedb Mont ome -Asber De ression Ratin Scale Total Score Parameter Placebo Cohort A Cohort B (1:8) (1:1) Baseline score # subjects N=4 N=14 N=14 mean (SD) 24.5 (7.9) 23.3 (4.1) 26.4 (4.4) Median 26.0 23.5 26.0 Change from # subjects N=13 basehne at Day 7 mean (SD) —11.4 (6.6) median - 1 3 .0 Comparison of Cohort A vs. Cohort B vs. s from PBO PBO baseline mean (SD) -4.96 (7.10) -7.88 (6.41) P value"< 0.256 0.054 Cohort A: 1:8 ratio of Compound 1: Buprenorphine (0.25mg:2mg for days 1 to 3 and 4mg for days 4 to 7) Cohort B: 1:1 ratio of Compound 1: Buprenorphine (4mg:4mg for days 1 to 3 and 8mg:8mg for days 4 to 7 Visual analog scales (VAS) were used to assess drug liking and other subjective drug effects. Subjects on active drug at the 1:8 ratio experienced greater subjective experiences of “Feeling High” (Table D) and “Feeling Sedated” (Table E) compared to the 1:1 ratio. The VAS s are reported as predose and postdose scores g the ude of difference in the subjective experiences. For example, on Day 7, the predose Cohort A VAS score for “Feeling High” was 5.8 and postdose score was 32.9, showing a difference of 27.1 score before and after dosing. In case of Cohort B, the predosing VAS score was 14.5 and postdosing was 19.6 showing only an increase of 5. 1. The comparison between the two cohorts shows that Cohort A experienced a significant increase in ng High” after the dosing compared to Cohort B.

TABLE D: Visual analog scale (VAS) results for “feeling high” Timepoint Placebo Cohort A (1 :8) Cohort B (1 :1) (mean[SD]) (mean[SD]) (mean[SD]) Day 1 e 18.0 (20.98) 8.6 (19.58) 9.1 (13.70) Postdose 48.0 (32.04) 54.4 (36.63) 29.4 (30.87) Day 2 Predose 6.8 (4.65) 14.8 (16.97) 22.5 (23.63) Postdose 9.0 (8.76) 39.3 ) 31.5 (29.02) Day 3 Predose 7.3 (2.63) 7.2 (11.35) 22.7 ) Postdose 6.3 (8.66) 41.8 (30.31) 35.5 (32.42) Day 4 Predose 6.3 (4.92) 10.2 (9.94) 17.5 (22.92) Postdose 7.8 (10.97) 57.1 (30.21) 19.1 (23.19) Day 5 e 7.3 (10.59) 6.3 (4.52) 15.7 (20.68) Postdose 23.8 (33.05) 35.1 (34.95) 19.5 (27.58) Day 6 Predose 22.8 (25.68) 4.6 (3.29) 15.5 ) Postdose 29.3 (32.35) 43.7 (30.21) 22.1 (30.36) Day 7 Predose 24.5 (26.85) 5.8 (5.37) 14.5 (23.57) Postdose 9.0 (8.76) 32.9 (30.14) 19.6 (29.51) TABLE E: Visual analog scale (VAS) results for ng sedated” Timepoint Placebo Cohort A (1 :8) Cohort B (1:1) (mean[SD]) (mean[SD]) (mean[SD]) Day 1 Predose 5.3 (9.24) 17.5 (26.98) 3.0 (4.96) se 36.5 (38.73) 60.4 ) 34.3 (31.51) Day 2 Predose 5.5 (6.61) 11.5 (12.80) 13.8 (15.42) Postdose 6.3 (6.75) 48.9 (28.69) 37.8 (31.21) Day 3 Predose 5.5 (5.32) 8.2 (8.64) 21.6 (27.76) Postdose 4.5 (3.87) 49.0 ) 31.2 (29.48) Day 4 Predose 5.8 (6.02) 12.2 (15.80) 22.4 (25.55) Postdose 2.8 (2.22) 38.4 ) 22.2 (24.54) Day 5 Predose 4.0 (3.56) 9.5 ) 13.9 (18.05) Postdose 30 .0 (34.55) 37.0 (31.65) 20.2 (23.79) Day 6 Predose 9.8 (14.93) 6.5 (5.68) 10.6 (14.65) se 21.3 (25.62) 44.8 (31.26) 19.5 (24.77) Day 7 Predose 10.8 (10.53) 17.0 (21.21) 9.7 (12.91) Postdose 5.3 (3.77) 30.3 (25.12) 14.5 (24.22) Bioanalytical method used for determining the Cmax for Compound-1: A method was validated for measuring Compound-1 in human plasma (K2EDTA). Samples were analyzed using a 50 uL aliquot volume and a protein-precipitation extraction procedure followed by liquid chromatography/tandem mass spectrometry (LC/MS/MS). Compound-1 concentrations were calculated with a 1/x2 linear sion over a concentration range of 0.250 to 100 ng/mL using naltrexone-d3 as an internal standard. Ten-fold dilution was successfully tested at 400 ng/mL for both analytes. The API 5000 was operated in the Selected Reaction Monitoring (SRM) mode under optimized conditions for detection of Compound-1, naltrexone-d3 ve ions formed by electrospray ionization. lytical method used for determining the Cmax for buprenorphine: A method was validated for measuring buprenorphine in human plasma (K2EDTA). Samples were analyzed using a 400 uL aliquot volume and a solid-phase extraction procedure followed by liquid chromatography/tandem mass spectrometry (LC/MS/MS). Buprenorphine concentrations were calculated with a l/x2 linear regression over a concentration range of 0.250 to 100 ng/mL. The API 5000 was operated in the Selected Reaction Monitoring (SRM) mode under optimized conditions for detection of buprenorphine and orphine-d4 positive ions formed by electrospray ionization.

The [3SS]GTPyS assay measures the fianctional properties of a compound by quantifying the level of ein activation following t binding in studies using stably transfected cells, and is considered to be a measure of the efficacy of a compound.

Membranes from CHO (Chinese Hamster Ovary) cells that stably expressed the cloned human u opioid receptor were used in the experiments. In a final volume of 0.5 mL, 12 different concentrations of Compound-l were incubated with 7.5 ug of CHO cell membranes that stably expressed the human u opioid receptor. The assay buffer ted of 50mM Tris- HCl, pH 7.4, 3 mM MgClz, 0.2 mM EGTA, 3 uM GDP, and 100 mM NaCl. The final concentration of [35S]GTPyS was 0.080 nM. Nonspecific binding was measured by inclusion of 10 uM GTPyS. g was initiated by the on of the membranes. After an tion of 60 min at 30°C, the samples were filtered through Schleicher & Schuell No. 32 glass fiber . The filters were washed three times with cold 50 mM Tris-HCl, pH 7.5, and were counted in 2 mL of Ecoscint scintillation fluid. Data are the mean Emax and EC50 values :: S.E.M. For calculation of the Emax values, the basal [35S]GTPyS binding was set at 0%, and the 100% [35S]GTPyS binding level was set at the maximum binding achieved with DAMGO.

Example 2 — Experiments were conducted in rats to assess the ability of opioid antagonists to modulate orphine-induced dopamine efflux in the Nucleus ens shell (NAc-sh) region of the mesolimbic region of the brain. Male rats weighing 300-400 grams were used for all studies.To measure the efflux of ne in the NAc-sh an in vivo microdialysis method was utilized in free-moving rats. This method allows the sampling of extracellular cerebrospinal fluid (CSF) from specific brain regions of interest and measurement of neurotransmitter concentrations following the analysis of sampled dialysate with C.

Each rat underwent surgical implantation of microdialysis guide cannula (CMA l2, CMA Microdialysis) to facilitate the insertion of the microdialysis probe later on. Rats were anesthetized with a mixture of ketamine/xylazine (80/6 mg/kg IP) and placed in a stereotaxic apparatus. Using bregma and skull as nce points, final coordinates were determined by The Rat Brain in Stereotaxic Coordinates (Paxinos and Watson, 2006) for the nucleus accumbens shell (+1.7 A/P, +-0.80 M/L, -7.8 D/V) and the guide cannula were lowered vertically into position (D/V = -5.8 from the skull) and fixed to the skull with glass-ionomer dental acrylic. Guide cannula were capped with dummy probes until microdialysis probe insertion. On the day prior to experimentation (3 -4 days post surgery), animals were weighed to determine riate dose for test articles. A microdialysis probe (CMA 12, 2mm membrane, CMA microdialysis) was then inserted through the guide cannula. Microdialysis probes were connected to a tether system allowing free nt and sterile artificial CSF (aCSF) (CMA microdialysis) was pumped via microsyringe pumps at a rate of 0.25 uL/min through the probe overnight for approximately 16 hours prior to experimentation. On the day following probe insertion, sterile aCSF perfusion was increased to 2.0ul/min and a pre- baseline equilibration period was established for at least 1.5 hours prior to initiating continuous collection of CSF. After the equilibration period a baseline neurotransmitter levels were determined for each animal over 1.75 hours. Following this baseline period, antagonist plus buprenonorphine (0.1mg/kg, SC) were administered and uous sampling of the ialysate conducted for an onal 4.25 hours. While continuously collected, the CSF was automatically fractioned into 15 minute periods using a chilled microfraction tor for the entire 6.0 hours collection period (1.75 baseline phase and 4.25 hour treatment phase). Each sample was analyzed via HPLC-EC to determine neurotransmitter concentration of dopamine based upon a six-point standard curve. The average dopamine per sample over the 4.25 treatment phase was used in all comparisons among treatment groups.

In rats buprenorphrine resulted in dose dependent increases in NAc-sh dopamine efflux n doses of 0.01 and 1 mg per kg (Figures 1 and 2). At doses of 0.1 and 1.0 mg per kg oral effects of buprenorphine were observed, including l sedation followed by hyperactivity. Consequently all additional experiments with u opioid antagonist used a dose of 0.1 mg per kg of buprenorphine since it ented the lowest dose associated with clear oral effects. As shown in Figure 3 each of the four antagonists evaluated resulted in linear dose-dependent decreases in NAc-sh dopamine efflux. However, the range in apparent potencies was considerable. Based on the AAnAI concept, this result was expected since neither differences in potency at the u opioid receptor or in the pharmacokinetic properties of the antagonists is taken into account.

TABLE F: C& values for Com ound-l Com ound-10 naltrexone and nalmefene with Buprenorphine 10. 1 mg/kg) _-Doseomnta- 0.03 Comma-1——- Com 0 ound-10 2.24 Naurexone —-- Nalmefene —-- Example 3 — The AAnAI concept was d to the study results obtained where NAc-sh ne efflux was attenuated with increasing doses of the four u—opioid receptor antagonist antagonists. Due to the inherent minor stress associated with PK sampling, and the sensitivity of neural chemistry to this stress, different groups of animals were required to establish circulating concentrations of buprenorphine and the nists at each dose level ted. Male rats ng between 300 - 400 grams, the same weight range used in the microdialysis studies, were used for these PK experiments. Since all animals received a fixed dose of buprenorphine, a commercial formulation of buprenorphine (Buprenex (Reckitt Benckiser)) was diluted to 0.1 mg/ml with sterile saline and then used as the vehicle for the required doses of Compound 1, Compound-10, naltrexone and nalmefene. This approached ensured that at each dose of the antagonist studied the concomitant dose of orphrine would be 0.1 mg per kg. All injections were made by the aneous route at the doses indicated in Table G. Sterile solutions of the test formulations (combination of antagonist with 0.1 mg/kg buprenorphine) were given subcutaneously (designated as time 0). Sample of blood were ted at 5, 15, 30, 60 and 120 minutes post dosing. For each blood sampling time point, rats were lightly etized using (3%) isoflourane anesthesia and approximately 200ul of blood was withdrawn from the lateral tail vein using a 27.5 gauge needle and placed into chilled K2 EDTA tubes. The collection tubes were inverted 10-15 times and then held on ice prior to centrifugation. Plasma was obtained by centrifuging samples for 2 minutes at 14,000 X g (1 1,500 RPM using Eppendorf 54l7R centrifuge rotor) at 4° C. The harvested samples of plasma were frozen at -80° C until assayed for buprenorphine and the antagonists (Compound 1, Compound 10, naltrexone or nalmefene) .

The Cmax values for each antagonist at the doses evaluated are shown in Table F. These values were used to calculate the AAnAI index associated with reductions in NAc-sh DA with increasing administered doses of the antagonist, taking into account differences in potency and PK properties among these compounds. As can be seen from Figure 3, the ility in the NAc-sh dopamine shown in Table E across the antagonist was essentially eliminated for Compound 1, Compound-10 and naltrexone by taking into account the in vitro potency and the Cmax achieved. Nalmefene did appear more potent in attenuating orphine- induced NAc-sh dopamine efflux, indicating that in rats other factors may influence the NAc-sh dopamine response to nalmefene.

TABLE G: Calculated AAnAI values for va in doses of Com ound-l Com ound-lO naltrexone and nalmefene with Bu reno hine 0.1 m /k Dose ofAnta Antagonist Anta_onist IC50 nM 0.03 0.1 0.3 Comma_—- Comoound-lO 0.23 2.5 8 Naurexone .8 Nalmefene Example 4 — The d range of the AAnAI to achieve a clinical anti-depressive effect is between values of about 0.5 and 5, and preferably about 0.7 and 2.2. These ranges take into account the nt variability in assay s used to experimentally determine values for the EC50 of buprenorphine and its concentration in plasma, and the IC50 of opioid antagonists and their concentrations in plasma for both non-clinical and al studies. As cited in Example 1, with plasma Cmax values for buprenorphine and Compound lresulting in AAnAI values of greater than 5, ts reported experiencing greater subjective feelings of high and sedation; undesirable traits for a buprenorphine and opioid antagonist combination ed for the treatment of depression. In the “forced swim test” (FST) rats are placed in a tank of water, from which they cannot escape, on two successive days; 15 minutes on the first day and 5 minutes on the second day. While in the water they will swim, attempt to climb the container wall or become “immobile” floating in the water. The total time rats are immobility increases between the first and second day. Drugs that have antidepressant effects in humans reduce lity time on day 2 and this model is frequently used to evaluate potential anti- WO 88243 depressive like activity of drugs. Strain of rat can also affect total lity time, with the Wistar-Kyoto (WKY) strain showing high immobility times. The WKY rat is spontaneously hypertensive and displays hormonal and depressive-like behavioral abnormalities. To explore the lower end of the range of the AAnAI, an experiment was conducted using three groups of rats in the PST paradigm. Rats received three te subcutaneous injections of either vehicle alone or a combination of buprenorphine (0.1 mg/kg) and Compound-l (0.3 or 3.0 mg/kg) at 1, l9, and 23 h after the first exposure to the swim tanks. At 24 h after the first swim, rats were retested for 5 minutes. Videos were scored manually for immobility time (in seconds) using a manual stop watch in 60 second intervals by a rater blinded to the treatment . A rat was judged to be immobile if it was making only movements necessary to keep its head above water. Results for this study are shown in Figure 5. Immobility time was significantly lower (p<0.05) in rats given the combination of orphine and nd 1 at 0.3 mg/kg, indicating an anti-depressive like action. An AAnAI value of approximately 2 was associated with this dose ation of buprenorphine and Compound 1. The anti- depressive like effect of the combination was lost when the dose of antagonist was raised to 3.0 mg/kg when an AAnAI of less than 0.3 was achieved. These data, along with the clinical data shown in Example 1 illustrate the importance of both the upper and lower boundaries of the AAnAI in order to achieve an anti-depressant activity without undesired side effects. s 6 and 7, show the complete attenuation of buprenorphine effects at the highest dose of Compound 1 for NAc-sh ne and 5-HIAA. These data further illustrate that at the desirable dose combination effects of buprenorphine are being modulated, but not eliminated, by Compound 1.

While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein t departing from the scope of the invention encompassed by the appended claims.

Claims (40)

CLAIMS What is claimed is:

1. A composition comprising buprenorphine and a µ opioid receptor antagonist, n the composition is characterized by an Agonist Antagonist Activity Index 5 (AAnAI) of between about 0.7 and about 2.2; wherein; wherein, EC50 represents the half maximal effective serum tration of buprenorphine, expressed as nM; IC50 represents the half maximal inhibitory concentration of the µ opioid nist in 10 humans, expressed as nM; Cmax(BUP) represents the peak serum or plasma tration of buprenorphine and/or a µ opioid receptor agonist metabolite of buprenorphine, expressed as nM; and Cmax(ANTAGONIST) represents the peak serum concentration of the µ opioid antagonist and/or a µ opioid or antagonist metabolite of said µ opioid antagonist, expressed 15 as nM wherein said antagonist is a compound of Formula I: R3 N (R8)s (R5)t X R7 R6 N R10 or a pharmaceutically acceptable salt or ester thereof wherein; s is 0, 1 or 2; t is 0, 1, 2, 3, 4, 5, 6, or 7; X is S or O; 5 R1 is selected from aliphatic, substituted aliphatic, aryl, substituted aryl, heterocyclyl or substituted heterocyclyl; each R2, R3, R4, R5, R6, R7 and R8 is independently selected from absent, hydrogen, halogen, -OR20, -SR20, -NR20R21, 20, -C(O)OR20, -C(O)NR20R21, - N(R20)C(O)R21, -CF3, -CN, -NO2, -N3, acyl, alkoxy, substituted alkoxy, alkylamino, 10 substituted alkylamino, dialkylamino, substituted dialkylamino, tuted or unsubstituted alkylthio, substituted or unsubstituted alkylsulfonyl, optionally tuted aliphatic, optionally substituted aryl, heterocyclyl or substituted heterocyclyl; each R9 and R10 is selected from hydrogen, aliphatic, tuted aliphatic, aryl, 15 substituted aryl, heterocyclyl or tuted heterocyclyl; alternatively, two of R2, R3, R4, R5, R6, R7 and R8 together with the atoms they are ed to form an optionally substituted ring; alternatively R2 and R3 together with the carbon they are attached to form a C=X group; wherein each R20 and R21 is independently selected from absent, hydrogen, halogen, -OH, -SH, -NH2, -CF3, -CN, - 20 NO2, -N3, -C(O)OH, -C(O)NH2, acyl, alkoxy, substituted , alkylamino, substituted alkylamino, lamino, substituted dialkylamino, substituted or unsubstituted alkylthio, tuted or unsubstituted alkylsulfonyl, aliphatic, tuted aliphatic, aryl or substituted aryl; and alternatively R9 and R10 together with the atom they are attached to form an optionally 25 substituted ring; alternatively two R5 groups, or an R5 and an R6 group, together with the carbon they are attached to form a C=X group.

2. The composition according to claim 1, wherein said AAnAI is between about 0.8 and about 2.1.

3. The composition according to claim 1, wherein said antagonist is a compound of Formula II: X R7 R6 R5 Formula II, or a ceutically acceptable salt or ester thereof wherein; R1 is n-c-C3H5, –(CH2)n-c-C4H7, –(CH2)n-c-C5H9, –(CH2)n-CH=CH2 or - 10 (CH2)n-CH=C(CH3)2 wherein n and m are independently 0, 1, 2 or 3; R6 and R7 are independently H, -OH or together R6 and R7 form an –O- or –S- group; R5 and R11 are independently H, -OH, OCH3 or together R5 and R1 form a =O or =CH2 group.

4. The composition according to claim 3, wherein said antagonist is selected from: OH N O OH O O OH O NH2 O OH O 1 2 3 OH OH O O O O OH O OH O OH NH2 NH2 NH2 4 5 6 N N OH OH O O O O O O O O O NH2 NH2 NH2 10 7 8 9 O OH O O OH O 10 11 and 12 or a pharmaceutically able salt or ester thereof.

5 5. The composition according to claim 4, wherein said antagonist is: O OH O or a pharmaceutically acceptable salt or ester thereof.

6. A composition comprising buprenorphine and a compound of Formula I: R3 N (R8)s (R5)t X R7 R6 N R10 Formula I, or a pharmaceutically acceptable salt or ester thereof wherein; s is 0, 1 or 2; 5 t is 0, 1, 2, 3, 4, 5, 6, or 7; X is S or O; R1 is ed from tic, substituted aliphatic, aryl, substituted aryl, heterocyclyl or substituted heterocyclyl; each R2, R3, R4, R5, R6, R7 and R8 is independently selected from absent, hydrogen, 10 halogen, -OR20, -SR20, -NR20R21, -C(O)R20, -C(O)OR20, -C(O)NR20R21, - N(R20)C(O)R21, -CF3, -CN, -NO2, -N3, acyl, alkoxy, substituted alkoxy, alkylamino, substituted mino, dialkylamino, substituted dialkylamino, substituted or unsubstituted alkylthio, substituted or unsubstituted alkylsulfonyl, optionally substituted aliphatic, optionally substituted aryl, heterocyclyl or substituted 15 heterocyclyl; Each R9 and R10 is ed from hydrogen, aliphatic, tuted aliphatic, aryl, substituted aryl, heterocyclyl or substituted cyclyl; alternatively, two of R2, R3, R4, R5, R6, R7 and R8 together with the atoms they are attached to form an optionally substituted ring; alternatively R2 and R3 together with 20 the carbon they are attached to form a C=X group; wherein each R20 and R21 is independently selected from absent, hydrogen, halogen, -OH, -SH, -NH2, -CF3, -CN, - NO2, -N3, -C(O)OH, -C(O)NH2, acyl, alkoxy, substituted alkoxy, alkylamino, substituted alkylamino, dialkylamino, substituted dialkylamino, tuted or unsubstituted alkylthio, substituted or unsubstituted ulfonyl, aliphatic, 25 substituted aliphatic, aryl or substituted aryl; and alternatively R9 and R10 together with the atom they are ed to form an optionally substituted ring; alternatively two R5 groups, or an R5 and an R6 group, together with the carbon they are attached to form a C=X group. 30

7. The composition ing to claim 6, wherein said compound of Formula I is a compound of Formula II: R 1 1 X R 7 R 6 R 5 NH 2 Formula II, or a pharmaceutically acceptable salt or ester thereof wherein; R1 is –(CH2)n-c-C3H5, –(CH2)n-c-C4H7, –(CH2)n-c-C5H9, –(CH2)n-CH=CH2 or - (CH2)n-CH=C(CH3)2 wherein n and m are independently 0, 1, 2 or 3; R6 and R7 are independently H, -OH or er R6 and R7 form an –O- or –S- group; 10 and R5 and R11 are independently H, -OH, OCH3 or together R5 and R1 form a =O or =CH2 group.

8. The composition according to claim 6, wherein said compound of a I is 15 selected from: OH N O OH O O OH O NH2 O OH O 1 2 3 OH OH O O O O OH O OH O OH NH2 NH2 NH2 4 5 6 N N OH OH O O O O O O O O O NH2 NH2 NH2 7 8 9 O OH O O OH O 10 NH2 10 11 and 12 . or a pharmaceutically acceptable salt or ester f.

9. A composition according to claim 8, wherein said compound is: O OH O or its pharmaceutically acceptable salt or ester.

10. Use of the composition of any one of the above claims for the preparation of a medicament for treating a depressive disorder comprising formulating the 5 medicament for administration to a subject in need thereof.

11. The use according to claim 10, wherein said depressive disorder is ed from major depressive disorder, chronic depression, severe unipolar recurrent major depressive episodes, dysthymic disorder, depressive neurosis and neurotic depression, 10 melancholic depression, atypical sion, reactive depression, treatment resistant depression, seasonal affective disorder and pediatric depression; premenstrual syndrome, premenstrual dysphoric disorder, hot s, bipolar disorders or manic depression, bipolar I disorder, bipolar II disorder and cyclothymic disorder. 15

12. The use according to claim 10, wherein said depressive disorder is major depressive disorder.

13. The use according to claim 11, n said major depressive disorder is resistant to two or more pressants.

14. The use ing to claim 12, wherein the antidepressants are selected from the group comprising selective serotonin ke inhibitors (SSRIs), Serotoninnorepinephrine reuptake inhibitors ), Monoamine e inhibitors (MAOIs) and Tricyclic antidepressants.

15. The use according to claim 10, wherein said depressive disorder is treatment resistant depression.

16. The use according to any of claims 10-15, wherein the medicament is ated for 5 administration orally or sublingually.

17. The use according to any of claims 10-16, wherein said subject exhibits one or more depressive symptoms selected from irritability, feelings of hopelessness and helplessness, inability to concentrate, sadness, insominia, appetite loss, lack of interest 10 in life’s activities, ts of suicide, dizziness, nausea, vomiting, hyperhidrosis, menorrhagia, pain in extremity, constipation, sedation, fatigue, g abnormal, flushing and somnolence.

18. The use according to any of claims 10-17, wherein said µ opioid nist is: O OH O 15 or a salt or ester thereof.

19. A composition comprising about 1mg to about 100 mg of buprenorphine and about 0.25 to about 100 mg of a nd of Formula I R3 N (R8)s (R5)t X R7 R6 N R10 or a ceutically acceptable salt, or ester thereof wherein; s is 0, 1 or 2; 5 t is 0, 1, 2, 3, 4, 5, 6, or 7; X is S or O; R1 is selected from aliphatic, substituted aliphatic, aryl, substituted aryl, heterocyclyl or substituted heterocyclyl; each R2, R3, R4, R5, R6, R7 and R8 is independently selected from absent, hydrogen, 10 halogen, -OR20, -SR20, 21, -C(O)R20, -C(O)OR20, R20R21, - N(R20)C(O)R21, -CF3, -CN, -NO2, -N3, acyl, alkoxy, substituted alkoxy, alkylamino, substituted alkylamino, dialkylamino, substituted dialkylamino, substituted or unsubstituted alkylthio, substituted or unsubstituted alkylsulfonyl, optionally substituted aliphatic, optionally substituted aryl, heterocyclyl or substituted 15 heterocyclyl; each R9 and R10 is ed from hydrogen, tic, substituted aliphatic, aryl, substituted aryl, heterocyclyl or substituted heterocyclyl; alternatively, two of R2, R3, R4, R5, R6, R7 and R8 er with the atoms they are ed to form an optionally substituted ring; alternatively R2 and R3 er with 20 the carbon they are attached to form a C=X group; wherein each R20 and R21 is independently selected from absent, hydrogen, halogen, -OH, -SH, -NH2, -CF3, -CN, - NO2, -N3, -C(O)OH, -C(O)NH2, acyl, alkoxy, substituted alkoxy, alkylamino, substituted alkylamino, dialkylamino, substituted dialkylamino, substituted or unsubstituted alkylthio, substituted or unsubstituted ulfonyl, aliphatic, substituted aliphatic, aryl or substituted aryl; and alternatively R9 and R10 together with the atom they are ed to form an optionally substituted ring; alternatively two R5 groups, or an R5 and an R6 group, together with 5 the carbon they are attached to form a C=X group.

20. The composition of claim 19 comprising about 2mg to about 50mg of buprenorphine.

21. The composition of claim 19 comprising about 3 to about 25 mg of buprenorphine.

22. The composition of claim 19 sing about 3 to about 10 mg of buprenorphine.

23. The composition according to any of claims 20-22 comprising about 0.25 to about 50 mg of a compound of Formula I.

24. The composition according to any of claims 19-22 comprising about 0.5 to about 25 mg of a compound of Formula I.

25. The composition according to any of claims 19-22 comprising about 1.0 to about 20 20 mg of a nd of Formula I.

26. The composition according to any of claims 19-22 comprising about 2.0 to about 10 mg of a compound of Formula I. 25

27. The composition according to any of claims 19-26 n said compound of Formula I is a compound of Formula II: R 1 1 X R 7 R 6 R 5 NH 2 or a pharmaceutically acceptable salt or ester thereof wherein; R1 is –(CH2)n-c-C3H5, –(CH2)n-c-C4H7, n-c-C5H9, –(CH2)n-CH=CH2 or - 5 (CH2)n-CH=C(CH3)2 wherein n and m are independently 0, 1, 2 or 3; R6 and R7 are independently H, -OH or together R6 and R7 form an –O- or –S- group; R5 and R11 are independently H, -OH, OCH3 or together R5 and R1 form a =O or =CH2 group.

28. The composition according to claim 27 n said compound is selected from: OH N O OH O O OH O NH2 O OH O 1 2 3 OH OH O O O O OH O OH O OH NH2 NH2 NH2 4 5 6 N N OH OH O O O O O O O O O 5 NH2 NH2 NH2 7 8 9 O OH O O OH O 10 10 11 and 12 . or a pharmaceutically able salt or ester thereof.

29. The composition according to claim 28, wherein said compound is: O OH O or a pharmaceutically acceptable salt or ester thereof.

30. Use of the composition of any one of claims 1-10 or 19-29 for the preparation of a ment for treating a depressive disorder selected from major depressive 5 disorder, chronic depression, severe unipolar recurrent major depressive episodes, dysthymic disorder, depressive neurosis and neurotic depression, melancholic sion, atypical depression, reactive depression, ent resistant depression, seasonal ive disorder and pediatric depression; premenstrual syndrome, premenstrual dysphoric disorder, hot flashes, bipolar disorders or manic depression, 10 bipolar I disorder, bipolar II disorder and cyclothymic disorder, wherein the ment is formulated for administration to a subject in need thereof.

31. Use of the composition of any one of claims 1-10 or 19-29 for the preparation of a medicament for treating a disease or disorder selected from obsessive compulsive 15 disorder, bulimia nervosa, panic er, posttraumatic stress disorder (PTSD), premenstrual dysphoric disorder (PMDD), social y disorder and generalized anxiety disorder (GAD), n the medicament is formulated for administration to a subject in need thereof. 20

32. A composition according to any of claims 1-10 or 19-29, wherein said composition has an AAnAI of about 1.3.

33. The composition according to claim 1, wherein said AAnAI is between about 0.9 and about 2.0.

34. The composition according to claim 1, wherein said AAnAI is between about 1.0 and about 1.8.

35. The composition according to claim 1, wherein said AAnAI is between about 1.1 and 5 about 1.6.

36. The composition according to claim 1, wherein said AAnAI is between about 1.2 and about 1.4. 10

37. A composition comprising 8mg buprenorphine and 8mg Compound-1, wherein Compound-1 has the structure: O OH O

38. Use of a composition in the manufacture of a medicament for treating a depressive 15 disorder sing formulating the medicament for administration to a patient in need thereof wherein the composition comprises 8mg orphine and 8mg Compound-1, wherein Compound-1 has the structure: O OH O 20

39. Use according to claim 38, wherein said depressive disorder is selected from major depressive er, chronic depression, severe unipolar recurrent major depressive episodes, mic disorder, depressive neurosis and neurotic depression, melancholic sion, atypical depression, reactive depression, treatment resistant depression, seasonal affective disorder and pediatric depression; premenstrual syndrome, premenstrual dysphoric disorder, hot flashes, bipolar disorders or manic depression, bipolar I disorder, bipolar II disorder and cyclothymic er. 5

40. Use according to claim 38, wherein said depressive disorder is major sive disorder.