WO2008075162A2

WO2008075162A2 - Selective mu opioid receptor antagonists for the treatment of female sexual dysfunction

Info

Publication number: WO2008075162A2
Application number: PCT/IB2007/003884
Authority: WO
Inventors: Vivienne Margaret Jackson; Christopher Peter Wayman
Original assignee: Pfizer Ltd Great Britain
Current assignee: Pfizer Ltd Great Britain
Priority date: 2006-12-15
Filing date: 2007-12-03
Publication date: 2008-06-26
Anticipated expiration: 2009-06-15
Also published as: JP2008150371A; TW200833338A; AR064368A1; WO2008075162A3

Abstract

The invention relates to methods of treatment of female sexual dysfunction with a selective antagonist of mu opioid receptors. Combination treatments with other classes of agent are also disclosed.

Description

COMPOUNDS FOR THE TREATMENT OF SEXUAL DYSFUNCTION

FIELD OF INVENTION

The present invention relates to the use of a selective mu opioid receptor antagonist for the treatment and/or prevention of female sexual dysfunction (FSD), in particular female sexual arousal disorder (FSAD).

The present invention further relates to a method of treatment and/or prevention of FSD, in particular FSAD using a selective mu opioid receptor antagonist.

BACKGROUND TO THE INVENTION

SEXUAL DYSFUNCTION

Sexual dysfunction (SD) is a significant clinical problem which can affect both males and females. The causes of SD may be both organic as well as psychological. Organic aspects of SD are typically caused by underlying vascular diseases, such as those associated with hypertension or diabetes mellitus, by prescription medication and/or by psychiatric disease such as depression. Physiological factors include fear, performance anxiety and interpersonal conflict. SD impairs sexual performance, diminishes self- esteem and disrupts personal relationships thereby inducing personal distress. In the clinic, SD disorders have been divided into female sexual dysfunction (FSD) disorders and male sexual dysfunction (MSD) disorders (Melman et al, J. Urology, 1999, 161, 5-11 ).

FSD can be defined as the difficulty or inability of a woman to find satisfaction in sexual expression. Male sexual dysfunction (MSD) is generally associated with erectile dysfunction, also known as male erectile dysfunction (MED) (Benet et a/ 1994 - Male Erectile dysfunction assessment and treatment options. Comp. Ther. 20: 669-673.). This invention is particularly beneficial for the prophylaxis and/or treatment of sexual dysfunction in the female - female sexual dysfunction (FSD), e.g. female sexual arousal disorder (FSAD).

FEMALE SEXUAL DYSFUNCTION (FSD)

In accordance with the invention, FSD can be defined as the difficulty or inability of a woman to find satisfaction in sexual expression. FSD is a collective term for several diverse female sexual disorders (Leiblum, S. R.

(1998) - Definition and classification of female sexual disorders. Int. J. Impotence Res., 10, S104-S106; Berman, J. R., Berman, L. & Goldstein, I.

(1999) - Female sexual dysfunction: Incidence, pathophysiology, evaluations and treatment options. Urology, 54, 385-391). The woman may have lack of desire, difficulty with arousal or orgasm, pain with intercourse or a combination of these problems. Several types of disease, medications, injuries or psychological problems can cause FSD, for example, antidepressant-induced female sexual dysfunction (Seqraves RT., Antidepressant-induced sexual dysfunction. J Clin Psychiatry. 1998;59 Suppl 4:48-54.; Taylor MJ., Strategies for managing antidepressant-induced sexual dysfunction: a review, Curr Psychiatry Rep. 2006 Dec;8(6):431-6).. Treatments in development are targeted to treat specific subtypes of FSD, predominantly desire and arousal disorders.

The categories of FSD are best defined by contrasting them to the phases of normal female sexual response: desire, arousal and orgasm (Leiblum, S. R. (1998) - Definition and classification of female sexual disorders. Int. J. Impotence Res., 10, S104-S106). Desire or libido is the drive for sexual expression. Its manifestations often include sexual thoughts either when in the company of an interested partner or when exposed to other erotic stimuli. Arousal is the vascular response to sexual stimulation, an important component of which is genital engorgement and includes increased vaginal lubrication, elongation of the vagina and increased genital sensation/sensitivity. Orgasm is the release of sexual tension that has culminated during arousal.

Hence, FSD occurs when a woman has an inadequate or unsatisfactory response in any of these phases, usually desire, arousal or orgasm. FSD categories include hypoactive sexual desire disorder, sexual arousal disorder, orgasmic disorders and sexual pain disorders. Although the compounds of the invention will restore the genital response and improve subjective arousal in response to sexual stimulation (as in female sexual arousal disorder), in doing so they may also improve the associated pain, distress and discomfort associated with intercourse and so treat other female sexual disorders.

Hypoactive sexual desire disorder is present if a woman has no or little desire to be sexual, and has no or few sexual thoughts or fantasies. This type of FSD can be caused by low testosterone levels, due either to natural menopause or to surgical menopause. Other causes include illness, medications, fatigue, depression and anxiety.

Female sexual arousal disorder (FSAD) is characterised by inadequate genital response to sexual stimulation. The genitalia do not undergo the engorgement that characterises normal sexual arousal. The vaginal walls are poorly lubricated, so that intercourse is painful. Orgasms may be impeded. Arousal disorder can be caused by reduced oestrogen at menopause or after childbirth and during lactation, as well as by illnesses, with vascular components such as diabetes, hypertension and atherosclerosis. Other causes result from treatment with diuretics, antihistamines, antidepressants e.g. selective serotonin re-uptake inhibitors (SSRIs) or antihypertensive agents.

Sexual pain disorders (includes dyspareunia and vaginismus) is characterised by pain resulting from penetration and may be caused by medications which reduce lubrication, endometriosis, pelvic inflammatory disease, inflammatory bowel disease or urinary tract problems but may also include noncoital sexual pain.

The prevalence of FSD is difficult to gauge because the term covers several types of problem, some of which are difficult to measure; such problems are typically poorly reported by the women experiencing them; and because the interest in treating FSD is relatively recent. Many women's sexual problems are associated either directly with the female ageing process or with chronic illnesses such as diabetes and hypertension. Clinical assessment and diagnosis tools are reviewed by Althof et al in J. Sex Med 2005, 2(Suppl. 3), pp146-153.

Because FSD consists of several subtypes that express symptoms in separate phases of the sexual response cycle, there is not a single therapy. Current treatment of FSD focuses principally on psychological or relationship issues. Treatment of FSD is gradually evolving as more clinical and basic science studies are dedicated to the investigation of this medical problem. Female sexual complaints are not all psychological in pathophysiology, especially for those individuals who may have a component of vasculogenic dysfunction (e.g. FSAD) contributing to the overall female sexual complaint. There are at present no drugs licensed for the treatment of FSD. Empirical drug therapy includes oestrogen administration (topically or as hormone replacement therapy), androgens or mood-altering drugs such as buspirone or trazodone. These treatment options are often unsatisfactory due to low efficacy or unacceptable side effects.

Since interest is relatively recent in treating FSD pharmacologically, therapy consists of the following: psychological counselling, over-the-counter sexual lubricants, and investigational candidates, including drugs approved for other conditions. These medications consist of hormonal agents, either testosterone or combinations of oestrogen and testosterone and more recently vascular drugs that have proved effective in male erectile dysfunction (MED). None of these agents has yet been demonstrated to be effective in treating FSD. This invention is particularly useful for the prophylaxis and/or treatment of female sexual arousal disorder (FSAD).

FEMALE SEXUAL AROUSAL DISORDER (FSAD)

The Diagnostic and Statistical Manual (DSM) IV of the American Psychiatric Association defines Female Sexual Arousal Disorder (FSAD) as being:

"... a persistent or recurrent inability to attain or to maintain until completion of the sexual activity adequate lubrication-swelling response of sexual excitement. The disturbance must cause marked distress or interpersonal difficulty. ...".

The arousal response consists of vasocongestion in the pelvis, vaginal lubrication and expansion and swelling of the external genitalia. The disturbance causes marked distress and/or interpersonal difficulty.

Basson et al (J. Urology, 2000, 163, 888-893, incorporated herein by reference) describes a revised classification system which follows the same general structure as DSM IV wherein the four major categories of dysfunction, that is desire (including hypoactive sexual desire disorder and sexual aversion disorder), arousal, orgasmic and sexual pain disorders are preserved and a new category of sexual pain including non-coital sexual pain is described. Non-coital sexual pain disorder is recurrent or persistent genital pain induced by non-coital sexual stimulation.

FSAD is a highly prevalent sexual disorder affecting pre-, peri- and postmenopausal (± hormone replacement therapy (HRT)) women. It is associated with concomitant disorders such as depression, cardiovascular diseases, diabetes and urogenital (UG) disorders. The primary consequences of FSAD are lack of engorgement/swelling, lack of lubrication and lack of pleasurable genital sensation. The secondary consequences of FSAD are reduced sexual desire, pain during intercourse and difficulty in achieving an orgasm.

It has recently been hypothesised that there is a vascular basis for at least a proportion of patients with symptoms of FSAD (Goldstein et al., Int. J. Impot. Res., 10, S84-S90,1998) with animal data supporting this view (Park et al., Int. J. Impot. Res., 9, 27-37, 1997).

Drug candidates for treating FSAD, which are under investigation for efficacy, are primarily erectile dysfunction therapies that promote circulation to male genitalia. They consist of two types of formulation, oral or sublingual medications (Apomorphine, Phentolamine, phosphodiesterase type 5 (PDE5) inhibitors, e.g. Sildenafil), and prostaglandin (PGE-i) that are injected or administered transurethrally in men and topically to the genitalia in women.

RJ. Levin teaches us that because "... male and female genitalia develop embryologically from the common tissue anlagen, [that] male and female genital structures are argued to be homologues of one another. Thus the clitoris is the penile homologue and the labia homologues of the scrotal sac. ..." (Levin, R.J. (1991), Exp. CHn. Endocrinol., 98, 61-69).

ANQRGASMIA^'

Anorgasmia is a form of sexual dysfunction, sometimes classified as a psychiatric disorder, where the patient cannot achieve orgasm, even with "adequate" stimulation. However it can also be caused by medical problems such as diabetic neuropathy, multiple sclerosis, pelvic trauma, hormonal imbalances, total hysterectomy, spinal cord injury and cardiovascular disease. Anorgasmia is far more common in females than in males.

OPIOID RECEPTORS In the study of opioid biochemistry, a variety of endogenous opioid compounds and non-endogenous opioid compounds has been identified. In this effort, significant research has been focused on understanding the mechanism of opioid drug action, particularly as it relates to cellular and differentiated tissue opioid receptors (Current Medicinal Chemistry, 2002, 1591-1603).

Opioid drugs are typically classified by their binding selectivity in respect of the cellular and differentiated tissue receptors to which a specific drug species binds as a ligand. These receptors include mu (μ), delta (δ) and kappa (K) receptors (Pharmacological Rev., 48, 1996, 567-592).

All three receptors are present in the central and peripheral nervous systems of many species including man. Activation of delta receptors produces antinociception in rodents and can induce analgesia in man, in addition to influencing motility of the gastrointestinal tract. (See Burks, T. F. (1995) in "The Pharmacology of Opioid Peptides", edited by Tseng, L. F., Harwood Academic Publishers).

The well known narcotic opiates such as morphine and its analogs are selective for the opioid mu receptor. Mu receptors mediate analgesia, respiratory depression, and inhibition of gastrointestinal transit. Kappa receptors mediate analgesia and sedation.

The existence of the opioid delta receptor (δ) [delta opioid receptor; DOR] is a relatively recent discovery which followed the isolation and characterization of endogenous enkephalin peptides, which are ligands for the delta receptor. Research in the past decade has produced significant information about the delta receptor, but a clear picture of its function has not yet emerged. Delta receptors mediate analgesia, but do not appear to inhibit intestinal transit in the manner characteristic of mu receptors.

OPIATES AND SEXUAL FUNCTION Opiates are involved in sexual function in the human and animal body, with effects on endocrine (hormone) function observed in human and animal studies.

Opiates have a long history as drugs which dampen the sexual urge. In female rodents opioid agonists administered centrally have been shown to inhibit or facilitate sexual behaviour depending upon the receptor type, doses of drugs used and brain areas stimulated.

The reduction of sexual receptivity has been observed in animal studies using opiate agonists, such as endogenous opiates or morphine; whereas nonselective opiate antagonists, such as naloxone or naltrexone, have been observed to increase female receptivity to sexual stimuli.

Naloxone and naltrexone are well-known non-selective opioid antagonists. There is some suggestion of a role of naloxone or naltrexone, in the treatment of male sexual dysfunction (impotence) (Psychoneuroendocrinology, 1979, 3, 231-236; Psychoneuroendocrinology 1989, 14, 103-111; Arch. Gen. Psychiatry, 1977, 34, 1179-1180; Arch. Med. Res., 2001 , 32, 221-226; Arch. Gen. Psychiatry, 1986, 43, 1986).

The evidence for the roles of such opiates in female sexual health is less clear - with one study of naloxone on a small number of sexually unresponsive women showing no effect on sexual arousal. Naloxone has also been reported to either enhance or inhibit orgasm (J. Sex Res., 1983, 19, 49-57). High doses of naloxone have been reported to produce immediate inhibition of sexual arousal (Neuroscience and Biobehavioral Reviews, 1987, 11 , 1-34).

Naltrexone has the capacity to cause hepatocellular injury when given in excessive doses. Naltrexone is contraindicated in acute hepatitis or liver failure, and its use in patients with active liver disease must be carefully considered in light of its hepatotoxic effects. The margin of separation between the apparently safe dose of naltrexone and the dose causing hepatic injury appears to be only five-fold or less. For this reason, naltrexone is accompanied by a "black box" warning on the package insert. Similarly, naloxone is associated with liver toxicity, and also carries a black box warning.

A problem that remains unsolved is the provision of therapy for female sexual dysfunction.

A further problem that remains unsolved is the provision of orally active therapy for female sexual dysfunction.

Surprisingly, it has now been found that mu selective opioid receptor antagonists are advantageous in treating FSD, preferably FSAD and/or Female Orgasmic Disorder (FOD).

SUMMARY OF THE INVENTION

According to a first aspect, there is provided the use of a selective mu opioid receptor antagonist (MOR), or a pharmaceutically acceptable salt thereof, in the preparation of a medicament for the treatment and/or prevention of female sexual dysfunction.

According to a second aspect, there is provided the use of a selective mu opioid receptor antagonist, or a pharmaceutically acceptable salt thereof, together with an auxiliary agent, or a pharmaceutically acceptable salt thereof, selected from one or more of:

i) compounds which modulate the action of natruretic factors in particular atrial naturetic factor;

ii) compounds which inhibit angiotensin-converting enzyme;

iii) substrates for NO-synthase;

iv) cholesterol lowering agents; v) estrogen receptor modulators and/or estrogen agonists and/or estrogen antagonists;

vi) phosphodiesterase (PDE) inhibitors;

vii) vasoactive intestinal protein (VIP), VIP mimetic, VIP analogue, a VIP receptor agonist or a VIP fragment, or an adrenoceptor antagonist with VIP combination;

viii) serotonin receptor agonists, antagonists or modulators;

ix) testosterone replacement agents or a testosterone implants;

x) selective androgen receptor modulators;

xi) estrogen, estrogen and medroxyprogesterone or medroxyprogesterone acetate (MPA) (i.e. as a combination), or estrogen and methyl testosterone hormone replacement therapy agents;

xii) progesterone, agonists or modulators of progesterone such as Gestodine, ethinylestradiol, ethynnodiol, etonogesterol implant, dyhydrogesterone, progestogen, totelle sekvens, norethynodrel or progesterone creams or gels such as MuProgest, Natragest and Fem-Gest;

xiii) modulators of transporters for noradrenaline, dopamine and/or serotonin; and

xiv) agonists or modulators for oxytocin/vasopressin receptors;

xv) melanocortin receptor agonists or modulators;

xvi) mono amine transport inhibitors; xvii) dopamine agonists (in particular selective D2, selective D3, selective D4 and selective D2-like agents);

xviii) α-adrenergic receptor antagonists (also known as α-adrenoceptor blockers, α-receptor blockers or α-blockers)

xix) anti-diabetic agents; and

xx) NPY receptor modulators (agonist and/or antagonist)

in the preparation of a medicament for the treatment and/or prevention of female sexual dysfunction.

According to a third aspect there is provided a compound that is a selective mu opioid receptor antagonist (MOR), or a pharmaceutically acceptable salt thereof, for use in the treatment and/or prevention of female sexual dysfunction.

According to a fourth aspect, there is provided a selective mu opioid receptor antagonist, or a pharmaceutically acceptable salt thereof, together with an auxiliary agent, or a pharmaceutically acceptable salt thereof, selected from one or more of:

ii) compounds which inhibit angiotensin-converting enzyme;

iii) substrates for NO-synthase;

iv) cholesterol lowering agents; . v) estrogen receptor modulators and/or estrogen agonists and/or estrogen antagonists;

vi) phosphodiesterase (PDE) inhibitors;

viii) serotonin receptor agonists, antagonists or modulators;

ix) testosterone replacement agents or a testosterone implants;

x) selective androgen receptor modulators;

xii) progesterone, agonists or modulators of progesterone such as Gestodine, ethinyl estradiol, ethynnodiol, etonogesterol implant, dyhydrogesterone, progestogen, totelle sekvehs, norethynodrel or progesterone creams or gels such as MuProgest, Natragest and Fem-Gest;

xiv) agonists or modulators for oxytocin/vasopressin receptors;

xv) melanocortin receptor agonists or modulators;

xix) anti-diabetic agents; and

xx) NPY receptor modulators (agonist and/or antagonist),

for use in the treatment and/or prevention of female sexual dysfunction.

Female sexual dysfunction may be one or more disorders selected form hypoactive sexual desire disorder, sexual arousal disorder, orgasmic disorder and sexual pain disorder.

According to a fifth aspect, there is provided a pharmaceutical composition comprising a selective mu opioid receptor antagonist, or a pharmaceutically acceptable salt thereof, and one or more auxiliary agents, or pharmaceutically acceptable salts thereof, selected from:

ii) compounds which inhibit angiotensin-converting enzyme;

iii) substrates for NO-synthase;

iv) cholesterol lowering agents;

v) estrogen receptor modulators and/or estrogen agonists and/or estrogen antagonists; vi) phosphodiesterase (PDE) inhibitors;

viii) serotonin receptor agonists, antagonists or modulators;

ix) testosterone replacement agents or a testosterone implants;

x) selective androgen receptor modulators;

xii) progesterone, agonists or modulators of progesterone such as Gestodine, ethinyl estradiol, ethynnodiol, etonogesterol implant, dyhydrogesterone, progestogen, totelle sekvens, norethynodrel or progesterone creams or gels such as MuProgest, Natragest and Fem-Gest;

xiv) agonists or modulators for oxytocin/vasopressin receptors;

xv) melanocortin receptor agonists or modulators;

xvi) mono amine transport inhibitors;

xvii) dopamine agonists (in particular selective D2, selective D3, selective D4 and selective D2-like agents); xviii) α-adrenergic receptor antagonists (also known as α-adrenoceptor blockers, α-receptor blockers or α-blockers)

xix) anti-diabetic agents; and

xx) NPY receptor modulators (agonist and/or antagonist).

According to a sixth aspect, there is provided a method for the treatment and/or prevention of female sexual dysfunction comprising administering to a subject in need thereof a therapeutic amount of a selective mu opioid receptor antagonist, or a pharmaceutically acceptable salt thereof.

According to a seventh aspect, there is provided a method for the treatment and/or prevention of female sexual dysfunction comprising administering to a subject in need thereof a therapeutic amount of a selective mu opioid receptor antagonist, or a pharmaceutically acceptable salt thereof, together with an auxiliary agent, or a pharmaceutically acceptable salt thereof, selected from one or more of i) to xx) listed above.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows displacement by Compound A of [³H]DAMGO (Mu Receptors), [³H]Naltrindole (Delta Receptors) and [³H]Diprenorphine (Kappa Receptors) from binding to their respective human opioid receptor.

Figure 2 shows inhibition by Compound A of the Increase in the Intracellular Ca⁺⁺ in CHO Cells Transiently Transfected with the Mu Receptor (Squares) and G_αQj₅ G-Protein or with the Kappa Receptor (Circles) and G_αQi₅DAMGO (400 nM) was the agonist used to stimulate the mu receptor and U-50,488 (400 nM) to activate the kappa receptor. Representative curves from triplicate measurements.

Figure 3: Effect of Compound A and naloxone hydrochloride on the mean receptivity score in OVX female rats treated with sub-threshold hormonal 4

16 primes - 5 Dg estrogen and 50 Dg progesterone. Receptivity score was calculated at pre-test (i.e. before administration of test compounds) and at 120 minutes post dose for Compound A (0.000167-16.7 mg/kg PO) and de-ionized water (5 mL/kg PO). Data are mean + SEM of the receptivity score: Compound A vehicle (n=7), 0.00167 mg/kg Compound A (n=5), 0.0167 mg/kg Compound A (n=8), 0.5 mg/kg Compound A (n=8), 1.67 mg/kg Compound A (n=8), 5 mg/kg Compound A (n=4), 16.7 mg/kg Compound A (n=5). Statistical significance was calculated using the Analysis of Variance (ANOVA) package from Excel add-in LabStats (Tessella) and the receptivity score for all treatment groups and time points was calculated as one mean for each animal on each dose of Compound A, de-ionized water (Compound A vehicle). "Compound A veh" (or "veh") = Compound A vehicle = de-ionized water (vehicle for Compound A). Predicted free plasma levels (nM) of Compound A are shown at the top of each dose response.

Figure 4: Effect of Compound A on the mean lordosis quotient in OVX female rats treated with sub-threshold hormonal primes - 5 Dg estrogen and 50 Dg progesterone. Lordosis quotient was calculated at 120 minutes post- dose for Compound A (0.00167-16.7 mg/kg PO). Data are mean + SEM of the lordosis quotient: Compound A vehicle (n=7), 0.00167 mg/kg Compound A (n=5), 0.0167 mg/kg Compound A (n=8), 0.5 mg/kg Compound A (n=8), 16.7 mg/kg Compound A (n=8), 5 mg/kg Compound A (n=4) and 16.7 mg/kg Compound A (n=5). Statistical significance for each dose group was calculated using the Analysis of Variance (ANOVA) package from Excel add- in LabStats (Tessella) against Compound A vehicle. The lordosis quotient for all dose groups were calculated as one mean for each animal on each dose of Compound A and Compound A vehicle (de-ionized water). "Compound A veh" (or "veh") = Compound A vehicle (vehicle for Compound A) = de-ionized water. (*=p<0.1, **=p<0.05, ***=p<0.001).

Figure 5: Effect of Compound A on the mean number of ear wiggles in OVX female rats treated with sub-threshold hormonal primes — 5μg estrogen and 50 μg progesterone. Ear wiggles were counted at 120 minutes post-dose for Compound A (0.00167-16.7 mg/kg P.O.). Data are mean + SEM: Compound A vehicle (n=7), 0.00167 mg/kg Compound A (n =5), 0.0167mg/kg Compound A (n =8), 0.5 mg/kg Compound A (n =8), 1.67 mg/kg Compound A (n=8), 5 mg/kg Compound A (n=4) and 16.7 mg/kg Compound A (n=5).

DETAILED DESCRIPTION

SELECTIVE MU OPIOID RECEPTOR ANTAGONIST

As used herein, the term "selective mu opioid receptor antagonist" refers to a compound which inhibits a physiological response when acting on a mu opioid receptor and which has selectivity for a mu opioid receptor, as compared with a kappa opioid and/or delta opioid receptor, greater than that exhibited by naltrexone in a functional assay.

"Selectivity" as used herein is a measure of the relative potency of a drug between two receptor subtypes for the same ligand. Potency can be determined, for example, by the assays as described in the protocols. Additionally, protocols for determination of potency and selectivity of ligands are described in Pharmacalogical Reviews, 39, 1987, 197-249, the entire content of which is incorporated herein by reference.

Preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a kappa opioid receptor, greater than that exhibited by naltrexone in a functional assay.

More preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a kappa opioid receptor, at least three times greater than that exhibited by naltrexone in a functional assay. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a kappa opioid receptor, at least five times greater than that exhibited by naltrexone in a functional assay, Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a. kappa opioid receptor, at least ten times greater than that exhibited by naltrexone in a functional assay. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a kappa opioid receptor, at least twenty times greater than that exhibited by naltrexone in a functional assay.

Preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, greater than that exhibited by naltrexone in a functional assay.

More preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, at least three times greater than that exhibited by naltrexone in a functional assay. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, at least five times greater than that exhibited by naltrexone in a functional assay. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, at least ten times greater than that exhibited by naltrexone in a functional assay. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, at least twenty times greater than that exhibited by naltrexone in a functional assay.

Preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a kappa opioid receptor, greater than that exhibited by naloxone in a functional assay.

More preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a kappa opioid receptor, at least three times greater than that exhibited by naloxone in a functional assay. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a kappa opioid receptor, at least five times greater than that exhibited by naloxone in a functional assay. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a kappa opioid receptor, at least ten times greater than that exhibited by naloxone in a functional assay. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a kappa opioid receptor, at least twenty times greater than that exhibited by naloxone in a functional assay.

Preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, greater than that exhibited by naloxone in a functional assay.

More preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, at least three times greater than that exhibited by naloxone in a functional assay. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, at least five times greater than that exhibited by naloxone in a functional assay. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, at least ten times greater than that exhibited by naloxone in a functional assay. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, at least twenty times greater than that exhibited by naloxone in a functional assay.

Preferably, the selective mu opioid receptor antagonist has a Ki for mu opioid receptors of less than 100 nM in a binding assay. More preferably, the selective mu opioid receptor antagonist has a Ki of less than 10 nM for mu opioid receptors in a binding assay. More preferably, the selective mu opioid receptor antagonist has a Ki for mu opioid receptors of less than 1 nM in a binding assay.

Preferably, the selective mu opioid receptor antagonist has a Ki for kappa opioid receptors of more than 10 nM in a binding assay. More preferably, the selective mu opioid receptor antagonist has a Ki for kappa opioid receptors of more than 100 nM in a binding assay. More preferably, the selective mu opioid receptor antagonist has a Ki for kappa opioid receptors of more than 1000 nM in a binding assay.

Preferably, the selective mu opioid receptor antagonist has a Ki for delta opioid receptors of more than 10 nM in a binding assay. More preferably, the selective mu opioid receptor antagonist has a Ki for delta opioid receptors of more than 100 nM in a binding assay. More preferably, the selective mu opioid receptor antagonist has a Ki for delta opioid receptors of more than 1000 nM in a binding assay.

Preferably, the selective mu opioid receptor antagonist has a Ki for mu opioid receptors of less than 100 nM in a functional assay. More preferably, the selective mu opioid receptor antagonist has a Ki of less than 10 nM for mu opioid receptors in a functional assay. More preferably, the selective mu opioid receptor antagonist has a Ki for mu opioid receptors of less than 5 nM in a functional assay.

Preferably, the selective mu opioid receptor antagonist has a Ki for kappa opioid receptors of more than 10 nM in a functional assay. More preferably, the selective mu opioid receptor antagonist has a Ki for kappa opioid receptors of more than 50 nM in a functional assay. More preferably, the selective mu opioid receptor antagonist has a Ki for kappa opioid receptors of more than 100 nM in a functional assay.

Preferably, the selective mu opioid receptor antagonist has a Ki for delta opioid receptors of more than 10 nM in a functional assay. More preferably, the selective mu opioid receptor antagonist has a Ki for delta opioid receptors of more than 100 nM in a functional assay. More preferably, the selective mu opioid receptor antagonist has a Ki for delta opioid receptors of more than 1000 nM in a functional assay.

Preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a kappa opioid receptor, by a factor of at least 5. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a kappa opioid receptor, by a factor of at least 10. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a kappa opioid receptor, by a factor of at least 50. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a kappa opioid receptor, by a factor of at least 100.

Preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, by a factor of at least 5. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, by a factor of at least 10. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, by a factor of at least 50. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor, as compared with a delta opioid receptor, by a factor of at least 100.

Preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor as compared with kappa and delta opioid receptors by a factor of at least 5. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor as compared with kappa and delta opioid receptors by a factor of at least 10. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor as compared with kappa and delta opioid receptors by a factor of at least 50. Still more preferably, the selective mu opioid receptor antagonist has selectivity for a mu opioid receptor as compared with kappa and delta opioid receptors by a factor of at least 100.

In a preferred embodiment, the selective mu opioid receptor antagonist inhibitor is a CNS-penetrant selective mu opioid receptor antagonist inhibitor.

As used herein, the term "antagonist" means any agent that reduces the action of another agent or target. The antagonistic action may result form a combination of the substance being antagonised (chemical antagonism) or the production of an opposite effect through a different target (functional antagonism or physiological antagonism) or as a consequence of competition for the binding site of an intermediate that links target activation to the effect observed (indirect antagonism).

As used herein the term "agonist" means any agent that enhances the action of or activates another agent or target. The term agonist includes a ligand that binds to receptors and thereby alters, typically increases, the proportion of them that are in an active form, resulting in a biological response.

Preferred compounds

Preferred compounds for use in the invention include those of the formula (I)

wherein X is H, halogen, -OH, -CN, -Ci-C₄ alkyl substituted with from one to three halogen atoms, or -0(CrC₄ alkyl), wherein the CrC₄ alkyl of -0(CrC₄ alkyl) is optionally substituted with from one to three halogen atoms;

Q is halogen, -OH, -0(C₁-C₄ alkyl), -NH₂, -NH(C₁-C₄ alkyl), -N(C₁-C₄ alkyl)(CrC₄ alkyl), -C(=O)NH₂, -C(=O)NH(Ci-C₄ alkyl), -C(=O)N(C_r C₄alkyl)(Ci-C₄ alkyl), -NHS(O)₂H, or -NHS(=0)₂R¹¹;

or Q may form a 5 or- 6 membered cycloalkyl or heterocycloalkyl ring with either carbon atom adjacent to the carbon atom to which it is attached, thereby forming a bicyclic fused ring system with the phenyl to which it is attached, wherein said heterocycloalkyl comprises from one to three hetero moities selected from O, S, -C(=O), and N, and wherein said cycloalkyl or heterocycloalkyl optionally contains one or two double bonds;

R¹ and R² are, with the carbon to which they are attached, connected to form a C₃-C₇ cycloalkyl or a 4-7 membered heterocycloalkyl comprising from one to three hetero moities selected from O, S, - C(=O), and N; and wherein said cycloalkyl or heterocycloalkyl optionally contains one or two double bonds; and wherein said cycloalkyl or heterocycloalkyl is optionally fused to a C₆-Cu aryl or 5-14 membered heteroaryl group;

wherein said C₃-C7 cycloalkyl or 4-7 membered heterocycloalkyl formed by R¹ and R² can each optionally be substituted by from one to three R¹² groups, and said optionally fused aryl or heteroaryl can each optionally independently be substituted with from one to six R¹² groups, wherein the R¹² groups are selected from R¹³, R¹⁶, -C₁-C₄ alkyl containing one or two unsaturated bonds, halogen, -OR¹³, -NO₂, -CN, - Cg-Cβcycloalkyl, -NR¹³R¹⁴, -NR¹³C(=O)R¹⁴, -C(O)NR¹³R¹⁴, - OC(=O)R¹³, -C(=O)OR¹³, -C(=O)R¹³, -NR¹³C(=O)OR¹⁴, NR¹³C(=O)NR¹⁴R¹⁵, -NR¹³S(O)₂R¹⁴, and -S(=O)₂R¹³;

R³ is Ci-C₄ alkyl, wherein said CrC₄ alkyl optionally contains one or two unsaturated bonds; 007/003884

24

R⁴ is -C₁-C₄ alkyl which may optionally contain one or two unsaturated bonds, -OH, -CN, -NO₂, -OR¹⁶, -NH₂, -NHR¹⁶, -NR¹⁶R¹⁷, or- NHC(=O)R¹⁶;

R⁵ and R⁸ are each independently H or methyl;

R⁶, R⁷, R⁹ and R¹⁰ are H;

R¹¹ is selected from C₁-C₄ alkyl, -(CrC₄ alkylene)-O-(Ci-C₄ alkyl), 4-(1- methylimidazole), -(C₁-C₄ alkylene)-NH₂, -(C₁-C₄ alkylene)-NH(C₁-C₄ alkyl), -(C₁-C₄ alkylene)-N(Ci-C₄ alkyl)(CrC₄ alkyl);

each R¹³, R¹⁴, and R¹⁵ is independently selected from H, R¹⁶, Ci-C₄ alkyl, halogen, -OH, -SH, -NH₂, -NH(C₁-C₄ alkyl), -N(C₁-C₄ alkyl)(C_rC₄ alkyl), -0(Ci-C₄ alkyl), -S(C₁-C₄ alkyl), -CN, -NO₂, -C(=O)(C_rC₄ alkyl), - C(=O)OH, -C(=O)O(C_rC₄ alkyl), -NHC(=O)(C_rC₄ alkyl), -C(=O)NH₂, and -C^O)N(C₁-C₄ alkyl)(C_rC₄ alkyl), or R¹³ and R¹⁴ wherein - NR¹³R¹⁴, may optionally be connected to form a 4 to 6 membered heterocycloalkyl or heteroaryl group, which heterorayl group optionally comprises from 1 to 3 further hetero moieties selected from N, S, O and -C(=O);

each R^1δ and R¹⁷ is independently selected from Ce-C₁₄ aryl and 5-14 membered heteroaryl, wherein said heteroaryl comprises from one to three hetero moities selected from O, S, -C(=O), and N, and wherein said aryl and heteroaryl are optionally substituted with from one to three substituents selected from C₁-C₄ alkyl optionally containing one or two unsaturated bonds, halogen, -OH, -SH, -NH₂, -NH(C₁-C₄ alkyl), - N(C₁-C₄ alkyl)(C_rC₄ alkyl),-O(C₁-C₄alkyl), -S(C.,-C₄alkyl), -CN, -NO₂, - C(=O)(C_rC₄alkyl), -C(=O)OH, -C(=O)O(C_rC₄ alkyl), -NHq=O)(C₁-C₄ alkyl), -C(=O)NH₂, and -C(=O)N(C-,-C₄ alkyl)(C_rC₄ alkyl);

and n is an integer selected from zero, 1 , 2, 3, 4, and 5; or a pharmaceutically acceptable salt thereof.

More preferred compounds are those of formula (II)

(H)

Wherein R ϊ1 , _D R2 , O R3 , _D R4⁴, Q, n and X having the meanings set out above.

Preferably, R³ is methyl, ethyl, isopropyl, or straight-chain propyl.

Preferably, R⁴ is -CN, -NO₂, -OH, -OCH₃, -CH₂OH, -NH₂, or -NHC(=O)CH₃. -

Preferably, Q is F, -OH, -C(=O)NH₂, -NHS(=O)₂CH₃, -NHS^O)₂CH₂CH₃, - NHS(=O)₂CH₂CH₂CH₃, -NHS(=0)2CH(CH₃)(CH₃), -NHS(=O)₂CH₂CH₂OCH₃, or -NHS(=O)₂(4-(1 -methylimidazole)).

Preferably, X is H, F, -OH, -C(=O)NH₂, or -CN.

Preferably, Q is halogen, -OH, -0(C₁-C₄ alkyl), -NH₂, -NH(C₁-C₄ alkyl), -N(C₁- C₄ alkyl)(C_rC₄ alkyl), -C(=O)NH₂, -C(=O)NH(C_rC₄ alkyl), -C (=O)N(Ci-C₄ 8^yI)(C₁-C₄ alkyl), -NHS(=O)₂H, or -NHS(=O)₂R¹¹. Preferably R¹ and R², with the carbon to which they are attached, are connected to form a cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl group, each optionally substituted with one or two R¹² groups.

Preferably R¹ and R², with the carbon to which they are attached, are connected to form a cyclopentyl group or a cyclohexyl group, which cyclopentyl group or cyclohexyl group is fused to a benzene ring, wherein said cyclopentyl group or cyclohexyl group and/or benzene ring are each optionally substituted with one or two R¹² groups.

Prefejably R¹ and R², with the carbon to which they are attached, are connected to form a cyclobutyl group, which cyclobutyl group is optionally substituted with one or two R¹² groups.

Suitable methods for the preparation of such compounds are taught in WO03/035622, the entire content of which is incorporated herein by reference.

Preferred compounds of the invention include:

Exo-N-(3-{6-ethyl-3-[3-(1-hydroxy-cyclohexyl)-propyl]-3-aza- bicyclo[3.1.0]hex-6-yl}-phenyl)-methanesulfonamide ;

Exo-N-(3-{6-ethyl-3-[3-(1-hydroxy-cyclohexyl)-propyl]-3-aza- bicyclo[3.1.0]hex-6-yl}-phenyl)-methanesulfonamide citrate;

Exo-N-(3-{6-ethyl-3-[3-(1-hydroxymethyl-cyclopentyl)-propyl]-3-aza- bicyclo[3.1.0]hex-6-yl}-phenyl)-methanesulfonamide;

Exo-N-(3-{6-ethyl-3-[3-(1-hydroxy-cyclohexyl)-propyl]-3-aza- bicyclo[3.1.0]hex-6-yl}-5-fluoro-phenyl)-methanesulfonamide;

Exo-N-(3-{6-ethyl-3-[3-(1-hydroxy-cyclohexyl)-propyl]-3-aza- bicyclo[3.1.0]hex-6-yl}-5-fluoro-phenyl)-methanesulfonamide besylate;

Exo-3-{6-ethyl-3-[3-(1-hydroxy-cyclohexyl)-propyl]-3-aza- bicyclo[3.1.0]hex-6-yl}-5-fluoro-benzamide;

Exo-3- {6-ethyl-3- [3- (1-hydroxy-cyclohexyl)-propyl]-3-aza-bicyclo [3.

1.0]hex-6-yl}-5- fluoro-benzamide tosylate; Exo-N-{3-[6^ethyl-3-(2-hydroxy-indan-2-ylmethyl)-3-aza- bicyclo[3.1.0]hθx-6-yl]-phenyl}-methanesulfonamic!e ;

Exo-N-{3-[6-ethyl-3-(2-hydroxy-indan-2-ylmethyl)-3-aza- bicyclo[3.1.0]hex-6-yl]-phenyl}-methanesulfonamide mesylate;

Exσ-2-methoxy-ethanesulfonic acid {3-[6-ethyl-3-(2-hydroxy-indan-2- ylmethyl)-3-aza-bicyclo[3.1.0]hex-6-yl]-phenyl}-amide;

Exo-2-methoxy-ethanesulfonic acid (3-{6-ethyl-3-[3-(1-hydroxy- cyclohexyl)-propyl]-3-aza-bicyclo[3.1.0 hex-6-yl}-phenyl)-amide;

Exo-3-[6-ethyl-3-(2-hydroxy-indan-2-ylmethyl)-3-aza-bicyclo[3.1.0]hex-

6-yl]- benzamide;

Exo-3-[6-ethyl-3-(2-hydroxy-indan-2-ylmethyl)-3-aza-bicyclo[3.1.0]hex-

6-yl]-benzamide citrate;

Exo-3-{6-ethyl-3-[3-(1-hydroxy-cyclohexyl)-propyl]-3-aza- b'icyclo[3.1.0]hex-6-yl}-phenol;

Exo-3-{6-ethyl-3-[3-(1-hydroxy-cyclohexyl)-propyI]-3-aza- bicyclo[3.1.0]hex-6-yl}- phenol citrate;

Exo-2-[6-ethyl-6-(3-hydroxy-phenyl)-3-aza-bicyclo[3.1.0]hex-3- ylmethy]]-indan-2-oi;

Exo-3-{6-Ethyl-3-[2-(2-hydroxy-indan-2-yl)-ethyl]-3-aza- bicyclo[3.1.0]hex-6-yl}- benzamide;

(+/-)-Exσ-2-Methoxy-ethanesulfonic acid {3-[6-ethyl-3-(2-hydroxy-

1 ,2,3,4- tetrahydro-naphthalen-2-ylmethyl)-3-aza-bicyclo[3.1.0]hex-6- yl]-phenyl}-amide;

(+)-Exo-N-{3-[6-Ethyl-3-(2-hydroxy-1 ,2,3,4-tetrahydro-naphthalen-2- ylmethyl)-3-aza-bicyclo[3.1.0]hex-6-yl]-phenyl}-methanesulfonamide;

(-)-Exo-N-{3-[6-Ethyl-3-(2-hydroxy-1 ,2,3,4-tetrahydro-naphthalen-2- ylmethyl)-3-aza-bicyclo[3.1.0]hex-6-yl]-phenyl}-methanesulfonamide;

Exo-3-[3-(2-Hydroxy-indan-2-ylmethyl)-6-propyl-3-aza- bicyclo[3.1.0]hex-6-yI]- benzamide;

Exo-3-{3-[3-(1-Hydroxy-cyclohexyl)-propyl]-6-propyI-3-aza- bicyclo[3.1.0]hex-6-yl}- benzamide;

Exo-N-(3-{3-[3-(1-Cyano-cyclohexyl)-propyl]-6-ethyl-3-aza- bicyclo[3.1.0]hex-6-yl}- phenyl)-methanesulfonamide; Exo-2-Methoxy-ethanesuifonic acid {3-[3-(2-hydroxy-indan-2-ylmethyl)- 6-propyl-3-aza-bicyclo[3.1.0]hex-6-yl]-phenyl}-amide; Exo-N-{3-[3-(2~Hydroxy-indan-2-ylmethyl)-6-isopropyl-3-aza- bicyclo[3.1.0]hex-6-yl]-phenyl}-methanesulfonamide; Exo-2-Methoxy-ethanesulfonic acid (3-{3-[3-(1 -hydroxy-cyclohexyl)- propyl]-6- isopropyl-3-aza-bicyclo[3.1.0]hex-6-yl}-phenyl)-amide; Exo-N-{3-[6-Ethyl-3-(c/s-1-hydroxy-3-phenyl-cyclobutylmethyl)-3-aza- bicyclo [3.1.0]hex-6-yl]-phenyl}-methanesulfonamidθ; Exo-3-[6-Ethyl-3-(c/s-1-hydroxy-3-phenyl-cyclobutylmethyl)-3-aza- bicyclo [3.1.0]hex-6-yl]-benzamide;

Exo-Ethanesulfonic acid {3-[6-ethyl-3-(2-hyroxy-indan-2~ylmethyl)-3- aza- bicyclo[3.1.0]hex-6-yl]-phenyl}-amide; and

Exo-Ethanesulfonic acid(3-{6-ethyl-3-[3-(1-hydroxy-cyclohexyl)-propyl]- 3-aza-bicyclo[3.1.0] hex-6-yl}-phenyl)-amide; and pharmaceutically acceptable salts thereof (where not specified).

A preferred compound is Exo-N-{3-[6-ethyl-3-(2-hydroxy-indan-2-ylmethyl)-3- aza-bicyclo[3.1.0]hex-6-yl]-phenyl} methanesulfonamide (also referred to herein as Compound A) and pharmaceutically acceptable salts thereof. This compound has the structure (III)

(III)

A specifically preferred compound is Exo-N-{3-[6-ethyl-3-(2-hydroxy-indan-2- ylmethyl)-3-aza-bicyclo[3.1.0]hex-6-yl]-phenyl} methanesulfonamide mesylate. This compound may be prepared according to the methods of preparation taught in WO03/035622, the entire content of which is incorporated by reference.

The term "alkyl", as used herein, unless otherwise indicated, includes saturated monovalent hydrocarbon radicals having straight or branched moieties. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, and t-butyl.

The term "cycloalkyl", as used herein, unless otherwise indicated, includes non- aromatic saturated cyclic alkyl moieties wherein alkyl is as defined above. Examples of cycloalkyl include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl.

The term "aryl", as used herein, unless otherwise indicated, includes an organic radical derived from an aromatic hydrocarbon by removal of one hydrogen, such as phenyl, naphthyl, indenyl, and fluorenyl.

"Heteroaryl", as used herein, refers to aromatic groups containing one or more heteroatoms (O, S, or N), preferably from one to four heteroatoms. A multicyclic group containing one or more heteroatoms wherein at least one ring of the group is aromatic is a "heteroaryl"group. The heteroaryl groups of this invention can also include ring systems substituted with one or more oxo moieties. Examples of heteroaryl groups are pyridinyl, pyridazinyl, imidazolyl, pyrimidinyl, pyrazolyl, triazolyl, pyrazinyl, quinolyl.isoquinolyl, tetrazolyl.furyl, thienyl, isoxazolyl, thiazolyl, oxazolyl, isothiazolyl, pyrrolyl,indolyl,benzimidazolyl, benzofuranyl, cinnolinyl, indazolyl, indolizinyl, phthalazinyl, triazinyl, isoindolyl, purinyl.oxadiazolyl, thiadiazolyl, furazanyl,benzofurazanyl, benzothiophenyl, benzotriazolyl,benzothiazolyl, benzoxazolyl, quinazolinyl, quinoxalinyl, naphthyridinyl, dihydroquinolyl, tetrahydroquinolyl.dihydroisoquinolyl, tetrahydroisoquinolyl, benzofuryl, furopyridinyl, pyrolopyrimidinyl, andazaindolyl. The foregoing groups, as derived from the compounds listed above, may be C-attached or N-attached where such is possible. For instance, a group derived from pyrrole may be pyrrol-1-yl (N-attached) or pyrrol-3-yl (C- attached). The terms referring to the groups also encompass all possible tautomers.

An alternative preferred mu selective opioid antagonist has the structure (IV)

(IV)

Compound (IV) may be prepared according to the method of Lett. Pept. Sci. 1998, 5, 193.

An alternative, preferred mu selective opioid antagonist is cyprodime. Cyprodime has the structure

(V)

Additional mu selective opioid receptor antagonists useful in the invention include Clocinnamox, Etonitazenyl isothiocyanate, CTOP (D-Phe-Cys-Tyr-D- Trp-Orn-Thr-Pen-Thr-NH2), CTP (D-Phe-Cys-Tyr-D-Trp-Lys-Thr-Pen-Thr- NH2), CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2), TCTOP (D-Tic- Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2), SMS-201 ,995 (D-Phe-Cys-Phe-D-Trp- Lys-Thr-ol), β-funaltrexamine, naloxonazine, alvimopan, LY-246736 and cyprodime.

Preferably the patient will also be receiving Hormone Replacement Therapy (HRT), even more preferably HRT and additional androgen therapy. Agents used may include estrogen, estrogen and medroxyprogesterone or medroxyprogesterone acetate (MPA) (i.e. as a combination), or estrogen and methyl testosterone hormone replacement therapy agent (e.g. HRT especially Premarjn, Cenestin, Oestrofeminal, Equin, Estrace, Estrofem, Elleste Solo, ^~ Estring, Eastraderm TTS, Eastraderm Matrix, Dermestril, Premphase, Prempro, Prempak, Premique, Estratest, Estratest HS, Tibolone). Agents for androgen therapy include testosterone replacement agent (including dehydroandrostendione), testosternone (Tostrelle), dihydrotestosterone or a testosterone implant.

Reference to an antagonist, an agonist or an inhibitor shall at all times be understood to include all active forms of such agents, including the free form thereof (e.g. the free and/or base form) and also all pharmaceutically acceptable salts, polymorphs, hydrates, silicates, stereo-isomers (e.g. diastereoisomers and enantiomers) and so forth. Active metabolites of any of the compounds, in any form, are also included.

Particular formulations of the compounds for either oral delivery or for topical application (creams, gels) are included in the invention and are described herein. An intravaginal formulation comprising a compound or combination of compounds as defined herein, preferably a formulation which is a cream or a gel, is also included in the invention.

A method of enhancing sexual function of a female comprising administering a selective mu opioid receptor antagonist to a healthy female is a further aspect of the invention. Yet a. further aspect of the invention is a method of screening for compounds useful for treating FSD, preferably FSAD and/or FOD, comprising screening compounds for selective mu opioid receptor antagonist activity and selecting compounds with a Ki of less than 50 nM, preferably with a Ki of less than 10 nM, even more preferably with a Ki of less than 1 nM in binding assays (see Example 1), or with a Ki of less than 50 nM, preferably a Ki of less than 10 nM, most preferably a Ki of less than 5 nM functional assays (see Example 1).

"Potency" as used herein is a measure of the concentration of a compound at which it is effective. The potency of a compound can be determined in a binding assay as described in the protocols, and potency in this context will refer to the Ki of the compound, i.e. to the concentration of competing ligand in a competition assay which would occupy 50% of the receptors if no radioligand were present. The potency of a compound can also be determined in a functional assay such as contractile assays for different tissues expressing different receptor subtypes as described in Example 1.

AUXILIARY ACTIVE AGENTS

Suitable auxiliary active agents for use in the combinations of the present invention include:

1 ) Compounds which modulate the action of natruretic factors in particular atrial naturetic factor (also known as atrial naturetic peptide), B type and C type naturetic factors such as inhibitors or neutral endopeptidase and in particular the compounds described and claimed in WO 02/02513, WO 02/03995, WO 02/079143 and EP-A-1258474, and especially the compound of Example 22 of WO 02/079143 (2S)-2{[1 -{3-4(- chlorophenyl)propyl]amino}carbonyl)cyclopentyl]methyl}-4-methoxybutanoic acid;

2) Compounds which inhibit angiotensin-converting enzyme such as * enapril, and combined inhibitors of angiotensin-converting enzyme and neutral endopeptidase such as omapatrilat.

{ . 3) Substrates for NO-synthase, such as L-arginine;

4) Cholesterol lowering agents such as statins (e.g. atorvastatin/ Lipitor- trade mark) and fibrates;

5) Estrogen receptor modulators and/or estrogen agonists and/or estrogen antagonists, preferably raloxifene or lasofoxifene, (-)-cis-6-phenyl-5- [4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-5,6,7,8-tetrahydronaphthalene-2-ol and pharmaceutically acceptable salts thereof the preparation of which is detailed in WO 96/21656;

6) PDE inhibitors such as PDE2 (e.g. erythro-9-(2-hydroxyl-3-nonyl)- adenine) and Example 100 of EP 0771799-incorporated herein by reference) and in particular a PDE5 inhibitor such as the pyrazolo [4,3-d]pyrimidin-7-ones disclosed in EP-A-0463756; the pyrazolo [4,3-d]pyrimidin-7-ones disclosed in EP-A-0526004; the pyrazolo [4,3-d]pyrimidin-7-ones disclosed in published international patent application WO 93/06104; the isomeric pyrazolo [3,4- d]pyrimidin-4-ones disclosed in published international patent application WO 93/07149; the quinazolin-4-ones disclosed in published international patent application WO 93/12095; the pyrido [3,2-d]pyrimidin-4-ones disclosed in published international patent application WO 94/05661 ; the purin-6-ones disclosed in published international patent application WO 94/00453; the pyrazolo [4,3-d]pyrimidin-7-ones disclosed in published international patent application WO 98/49166; the pyrazolo [4,3-d]pyrimidin-7-ones disclosed in published international patent application WO 99/54333; the pyrazolo [4,3- d]pyrimidin-4-ones disclosed in EP-A-0995751 ; the pyrazolo [4,3-d]pyrimidin- 7-ones disclosed in published international patent application WO 00/24745; the pyrazolo [4,3-d]pyrimidin-4-ones disclosed in EP-A-0995750; the compounds disclosed in published international application WO95/19978; the compounds disclosed in published international application WO 99/24433 and the compounds disclosed in published international application WO 93/07124; the pyrazolo [4,3-d]pyrimidin-7-ones disclosed in published international application WO 01/27112; the pyrazolo [4,3-d]pyrimidin-7-ones disclosed in published international application WO 01/27113; the compounds disclosed in EP-A-1092718 and the compounds disclosed in EP-A-1092719;

7) Vasoactive intestinal protein (VIP), VIP mimetic, VIP analogue, more particularly mediated by one or more of the VIP receptor subtypes VPAC1 ,VPAC or PACAP (pituitary adenylate cyclase activating peptide), one or more of a VIP receptor agonist or a VIP analogue (e.g. Ro 125 1553) or a VIP fragment, one or more of a adrenoceptor antagonist with VIP combination (e.g. Invicorp, Aviptadil);

8) A serotonin receptor agonist, antagonist or modulator, more particularly agonists, antagonists or modulators for 5HT1A (including VML 670 [WO02/074288] , flibanserin [US2003/0104980] and OPC 14523 [US2007/0142395]), 5HT2A, 5HT2C, 5HT3 and/or 5HT6 receptors, including those described in WO-09902159, WO-00002550 and/or WO-00028993;

9) A testosterone replacement agent, including dehydroandrostendione, testosterone (including Tostrelle and Intrinsa), dihydrotestosterone or a testosterone implant;

10) Selective androgen receptor modulators eg LGD-2226;

11) Estrogen, estrogen and medroxyprogesterone or medroxyprogesterone acetate (MPA) (i.e. as a combination), or estrogen and methyl testosterone hormone replacement therapy agent (e.g. HRT especially Premarin, Cenestin, Oestrofeminal, Equin, Estrace, Estrofem, Elleste Solo, Estring, Eastraderm TTS, Eastraderm Matrix, Dermestril, Premphase, Preempro, Prempak, Premique, Estratest, Estratest HS,

Tibolone);

12) Progesterone, agonists or modulators of progesterone such as Gestodine, ethinylestradiol, ethynnodiol, etonogesterol implant, dyhydrogesterone, progestogen, totelle sekvens, norethynodrel or progesterone creams or gels such as MuProgest, Natragest and Fem-Gest; 13) A modulator of transporters for noradrenaline, dopamine and/or serotonin, such as bupropion, GW-320659; and

14) An agonist or modulator for oxytocin/vasopressin receptors, preferably a selective oxytocin agonist or modulator;

15) A melanocortin receptor agonist or modulator (including PT-141 [Bremelanotide] and melanotan-ll and preferably a selective MCR3, MCR3/4 and/or MCR4 melanocortin agonist or modulator (including MB-243, RO0282425 and the compounds described in WO2005/77935 and PCT/IB07/000456);

16) Mono amine transport inhibitors, such as Noradrenaline (norepinephrine) re-uptake inhibitors (NRIs), especially selective NRIs such as reboxetine, either in its racemic (R,R/S,S) or optically pure (S, S) enantiomeric form, particularly (S,S)-reboxetine; Serotonin Re-uptake Inhibitors (SRIs) including selective serotonin reuptake inhibitors (SSRIs) such as dapoxetine, paroxetine, 3-[(dimethylamino)methyl]-4-[4- (methylsulfanyl)phenoxy]benzenesulfonamide (Example 28, WO 0172687), 3- [(dimethylamino)methyl]-4-[3-methyl-4-

(methylsulfanyl)phenoxy]benzenesulfonamide (Example 12, WO 0218333), N- methyl-Λ/-({3-[3-methyl-4-(methylsulfanyl)phenoxy]-4-pyridinyl}methyl)amine (Example 38, PCT Application no PCT/IB02/01032); or Dopamine Re-uptake Inhibitors (DRIs);

17) Dopamine agonists (in particular selective D2, selective D3, selective D4 and selective D2-like agents) such as Pramipexole (Pharmacia Upjohn compound number PNU95666), ropinirole, apomorphine, surmanirole, quinelorane, PNU-142774, bromocriptine, carbergoline, Lisuride, compounds described in WO2004/052372, WO2005/116027, WO2005/115985; 18) One or more α-adrenergic receptor antagonists (also known as α-adrenoceptor blockers, α-receptor blockers or α-blockers); suitable αr adrenergic receptor antagonists include: phentolamine, prazosin, phentolamine mesylate, trazodone, alfuzosin, indoramin, naftopidil, tamsulosin, phenoxybenzamine, rauwolfa alkaloids, Recordati 15/2739, SNAP 1069, SNAP 5089, RS17053, SL 89.0591 , doxazosin, Example 19 of WO9830560, terazosin and abanoquil; suitable α₂- adrenergic receptor antagonists include dibenarnine, tolazoline, trimazosin, efaroxan, yohimbine, idazoxan and clonidine; suitable non-selective α-adrenergic receptor antagonists include dapiprazole; further α- adrenergic receptor antagonists are described in PCT application WO99/30697 published on 14th June 1998 and US patents: 4,188,390; 4,026,894; 3,511 ,836; 4,315,007; 3,527,761 ; 3,997,666; 2,503,059; 4,703,063; 3,381 ,009; 4,252,721 and 2,599,000 each of which is incorporated herein by reference;

19) Anti-diabetic agents such as aldose reductase inhibitors, e.g.zolpolrestat; glycogen phosphorylase or sorbitol dehydrogenase inhibitors; and

20) One or more NPY receptor modulators (agonist and/or antagonist) e.g, NPY-Y1 , NPY- Y2, NPY- Y5 or a modulator with combined pharmacologies at these receptors.

By cross reference herein to compounds contained in patents and patent applications which can be used in accordance with invention, we mean the therapeutically active compounds as defined in the claims (in particular of claim 1) and the specific examples (all of which is incorporated herein by reference).

If a combination of active agents is administered, then they may be administered simultaneously, separately or sequentially.

Auxiliary Agents - PDE5 Inhibitors Particularly preferred herein as auxiliary active agents are PDE5 (or PDEV) inhibitors.

The suitability of any particular cGMP PDE5 inhibitor can be readily determined by evaluation of its potency and selectivity using literature methods followed by evaluation of its toxicity, absorption, metabolism, pharmacokinetics, etc in accordance with standard pharmaceutical practice.

IC50 values for the cGMP PDE5 inhibitors may be determined using the PDE5 assay (see hereinbelow and WO01/27113).

Preferably the cGMP PDE5 inhibitors used in the pharmaceutical combinations according to the present invention are selective for the PDE5 enzyme. Preferably (when used orally) they are selective over PDE3, more preferably over PDE3 and PDE4. Preferably (when oral), the cGMP PDE5 inhibitors of the invention have a selectivity ratio greater than 100 more preferably greater than 300, over PDE3 and more preferably over PDE3 and PDE4.

Selectivity ratios may readily be determined by the skilled person. IC50 values for the PDE3 and PDE4 enzyme may be determined using established literature methodology, see S A Ballard et al, Journal of Urology, 1998, vol. 159, pages 2164-2171 and as detailed herein after.

Suitable cGMP PDE5 inhibitors for the use according to the present invention include:

The pyrazolo [4,3-d]pyrimidin-7-ones disclosed in EP-A-0463756; the pyrazolo [4,3-d]pyrimidin-7-ones disclosed in EP-A-0526004; the pyrazolo [4,3- d]pyrimidin-7-ones disclosed in published international patent application WO 93/06104; the isomeric pyrazolo [3,4-d]pyrimidin-4-ones disclosed in published international patent application WO 93/07149; the quinazolin-4- ones disclosed in published international patent application WO 93/12095; the pyrido [3,2-d]pyrimidin-4-ones disclosed in published international patent application WO 94/05661 ; the purin-6-ones disclosed in published international patent application WO 94/00453; the pyrazolo [4,3-d]pyrimidin-7- ones disclosed in published international patent application WO 98/49166; the pyrazolo [4,3-d]pyrimidin-7-ones disclosed in published international patent application WO 99/54333; the pyrazolo [4,3-d]pyrimidin-4-ones disclosed in EP-A-0995751 ; the pyrazolo [4,3-d]pyrimidin-7-ones disclosed in published international patent application WO 00/24745; the pyrazolo [4,3-d]pyrimidin-4- ones disclosed in EP-A-0995750; the hexahydropyrazino [2',1'[6,I]PyHdO [3,4- b]indole-1 ,4-diones disclosed in published international application WO95/19978; the imidazo[5,1-f][1 ,2_;4]triazin-ones disclosed in EP-A-1092719 and in published international application WO 99/24433; and the bicyclic compounds disclosed in published international application WO 93/07124; all of which are incorporated herein by reference.

Further examples of suitable PDE5 inhibitors for use herein include: the pyrazolo [4,3-d]pyrimidin-7-ones disclosed in published international application WO 01/27112; the pyrazolo [4,3-d]pyrimidin-7-ones disclosed in published international application WO 01/27113; the compounds disclosed in EP-A-1092718 and the compounds disclosed in EP-A-1092719; the tricyclic compounds disclosed in EP-A-1241170; the alkyl sulphone compounds disclosed in published international application WO 02/074774; the compounds disclosed in published international application WO 02/072586; the compounds disclosed in published international application WO 02/079203; the compounds described in WO01187882; the compounds described in WO0056719, e.g. BMS-341400; the compounds described in WO9964004, e.g. BMS-263504; the compounds described in EP-1057829 (Jordanian Pharmaceutical Manufacturing and Medical Equipment Company); the compounds described in EP722936; the compounds described in WO93/07124; the compounds described in WO98/06722; the compounds described in WO98/06722; the compounds described in EP579496 and in particular ONO1505 (Ono); the compounds described in WO97/03070 and in particular OPC35564 (Otsuka); and the compounds described in WO02/074312; all of which are incorporated herein by reference.

Yet further examples of suitable PDE5 inhibitors for use herein include the carboline derivatives described in WO03000691 , WO02098875, WO02064591 , WO02064590 and WO0108688, the pyrazino [1',2¹Ii , 6] pyrido [3,4-B] indole 1 ,4-dione derivatives described in WO02098877, the tetracyclic compounds described in WO02098428, the compounds described in WO02088123 and WO0200656, the condensed pyrazindione derivatives described in WO0238563 and WO02000657, the indole derivatives described in WO0236593,- the condensed pyrindole derivatives described in WO0228865 and WO0228859, the hexahydropyrazino[r,2':1 ,6]-pyrido [3,4-B] indole-1 ,4-dione derivatives described in WO0228858 and WO0194345, the fused heterocyclic derivatives described in WO0210166, the cyclic GMP specific phosphodiesterase inhibitors described in WO0200658, the tetracyclic diketopiperazine compounds described in WO0194347, the compounds described in WO0298877 and the compounds described in use application WO0219213, all of which are incorporated herein by reference.

Yet further examples of suitable PDE5 inhibitors for use herein include the compounds described in WO0164192, DE 10104800, WO0259126, DE10104095, WO0249651 , DE10063224, DE10060338, DE10058662 and WO0200660, all of which are incorporated herein by reference.

Still other PDE5 inhibitors useful in conjunction with the present invention include:

4-bromo-5-(pyridylmethylamino)-6-[3-(4-chlorophenyl)-propoxy]-3(2H)pyrid azinone;

1-[4-[(1 ,3-benzodioxol-5-ylmethyl)amiono]-6-chloro-2-quinozolinyl]-4- piperidine-carboxylic acid.monosodium salt;

(+)-cis-5,6a, 7,9,9, 9a-hexahydro-2-[4-(trifluoromethyl)-phenylmethyl-5-methyl- cyclopent-4,5]imidazo[2,1-b]purin-4(3H)one; furazlocillin; cis^-hexyl-δ-methyl-S^.δ.θaJ.δ^.θa-octahydrocyclopent^.δJ-imidazo^.i- b]purin-4-one; 3-acetyl-1 -(2-chlorobenzyl)-2-propylindole-6- carboxylate; 3-acetyl-1-(2-chlorobenzyl)-2-propylindole-6-carboxylate; 4-bromo-5-(3-pyridylmethylamino)-6-(3-(4-chlorophenyl) propoxy)-

3(2H)pyridazinone;

1-methyl-5(5-morpholinoacetyl-2-n-propoxyphenyl)-3-n-propyl-1 ,6-dihydro-7H- pyrazolo(4,3-d)pyrimidin-7-one;

1-[4-[(1 ,3-benzodioxol-5-ylmethyl)amino]-6-chloro-2-quinazolinyl]-4- piperidinecarboxylic acid, monosodium salt;

Pharmaprojθcts No. 4516 (Glaxo Wellcome); Pharmaprojects No. 5051 (Bayer); Pharmaprojects No. 5064 (Kyowa Hakko; see WO 96/26940); Pharmaprojects No. 5069 (Schering Plough); ER-118585, E-8010, E-4021 and E-4010 (Eisai); Bay-38-3045 & 38-9456 (Bayer); FR181074, FR229934 and FR226807 (Fujisawa); TA-1032, T-0156 and TA-1790 (Tanabe Seiyaku); EMD82639 and EMR6203 (Merck); LAS34179 and LAS35917 (Almirall); Sch- 51866; BMS-223131 (Bristol Myers Squibb); NCX911 (Nicox); and ABT-724 and ABT-670 (Abbott).

Preferred PDE5 inhibitors for the use according to the present invention include:

(')

5-[2-ethoxy-5-(4-methyl-1~piperazinylsuIphonyl)phenyl]-1-methyl-3-n-propyl- 1 ,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one (sildenafil) also known as 1-[[3- (6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)-4- ethoxyphenyl]sulphonyl]-4-methylpiperazine (see EP-A-0463756);

(ii) 5-(2-ethoxy-5-morpholinoacetylphenyl)-1-methyl-3-n-propyl-1 ,6-dihydro-7H- pyrazolo[4,3-d]pyrimidin-7-one (see EP-A-0526004);

(iii)

3-ethyl-5-[5-(4-ethylpiperazin-1-ylsulphonyl)-2-n-propoxyphenyl]-2-(pyridin-2- yl)methyl-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one (see WO98/49166); (iv)

3-θthyl-5-[5-(4-ethylpiperazin-1-ylsulphonyl)-2-(2-methoxyethoxy)pyridine-3- yl]-2-(pyπdin-2-yl)mθthyl-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimiclin-7-onθ (see WO99/54333);

(V)

(+)-3-ethyl-5-[5-(4-ethylpiperazin-1-ylsulphonyl)-2-(2-methoxy-1 (R)- methylethoxy)pyridin-3-yl]-2-methyl-2,6-dihydro-7H-pyrazolo[4,3-d]pyrinnidin- 7-one, also known as 3-ethyl-5-{5-[4-ethylpiperazin-1-ylsulphonyl]-2-([(1 R)-2- methoxy-1-methylethyl]oxy)pyridin-3-yl}-2-methyl-2,6-dihydro-7H- pyrazolo[4,3-d] pyrimidin-7-one (see WO99/54333);

(vi)

5-[2-ethoxy-5-(4-ethylpiperazin-1-ylsulphonyl)pyridin-3-yl]-3-ethyl-2-[2- methoxyethyl]-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one, also known as 1-{6-ethoxy-5-[3-ethyl-6,7-dihydro-2-(2-methoxyethyl)-7-oxo-2H-pyrazolo[4,3- d]pyrimidin-5-yl]-3-pyridylsulphonyl}-4-ethylpiperazine (see WO01/27113, Example 8);

(vii)

5-[2-iso-Butoxy-5-(4-ethylpiperazin-1-ylsulphonyl)pyridin-3-yl]-3-ethyl-2-(1- methylpiperidin-4-yl)-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one (see WO 01/27113, Example 15);

(viii)

5-[2-Ethoxy-5-(4-ethylpiperazin-1-ylsulphonyl)pyridin-3-yl]-3-ethyl-2-phenyl- 2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one (see WO 01/27113, Example 66);

(ix)

5-(5-Acetyl-2-propoxy-3-pyridinyl)-3-ethyl-2-(1-isopropyl-3-azetidinyl)-2,6- dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one (see WO 01/27112, Example 124); (X)

5-(5-Acetyl-2-butoxy-3-pyridinyl)-3-ethyl-2-(1-ethyI-3-azetidinyl)-2_>6-dihyclro- 7H-pyrazolo[4,3-d]pyrimidin-7-one (see WO 01/27112, Example 132);

(xi)

(6R, 12aR)-2,3,6,7, 12,12a-hexahydro-2-methyl-6-(3,4-methylenedioxyphenyl)- pyrazinoβM'tf.itøyridoβ^-bilindole-I Λ-dione (tadalafil, iC-351 , Cialis®), i.e. the compound of examples 78 and 95 of published international application WO95/19978, as well as the compound of examples 1 , 3, 7 and 8;

(xϊi)

2-[2-ethoxy-5-(4-ethyl-piperazin-1-yl-1-sulphonyl)-phenyl]-5-methyl-7-propyl- 3H-imidazo[5,1-fJ[1 ,2,4]triazin-4-one (vardenafil) also known as 1-[[3-(3,4- dihydro-5-methyl-4-oxo-7-propylimidazo[5,1-f]-as-triazin-2-yl)-4- ethoxyphenyl]sulphonyl]-4-ethylpiperazine, i.e. the compound of examples 20, 19, 337 and 336 of published international application WO99/24433;

(xiii) the pyrazolo [4,3-d]pyrimidin-4-ones disclosed in WO00/27848, in particular N-[[3-(4,7-dihydro-1 -methyl-7-oxo-3-propyl-1 H-pyrazolo[4,3-d]- pyrimidin-5-yl)-4-propxyphenyl]sulfonyl]-1-methyl2-pyrrolidinepropanamide [DA-8159 (Example 68 of WO00/27848)];

(xiv) the compound of example 11 of published international application WO93/07124;

(xv) 4-(4-chlorobenzyl)amino-6,7,8-trimethoxyquinazoline;

(xvi) 7,8-dihydro-8-oxo-6-[2-propoxyphenyl]-1 H-imidazo[4,5-g]quinazoline;

(xvii)

1-[3-[1-[(4-fluorophenyl)methyl]-7,8-dihydro-8-oxo-1 H-imidazo[4,5- g]quinazolin-6-yl]-4-propoxyphenyl]carboxamide;

(xviii) 5-(5-acetyl-2-butoxy-3-pyridinyl)-3-ethyl-2-(1-ethyl-3-azetidinyl)-2,6-dihyclro- 7H-pyrazolo[4,3-d]pyrimidin-7~one; and

(xix)

1-{6-ethoxy-5-[3-ethyl-6,7-dihydro-2-(2-methoxyethyl)-7-oxo-2H-pyrazolo[4,3- d]pyrimidin-5-yl]-3-pyridylsulfonyl}-4-ethylpiperazine;

(XX)

7-(3-bromo-4-methoxyphenylmethyl)-1-ethyl-8-{[(1 R,2R)- 2- hydroxycyclopropyl]amino}-3-(2-hydroxyethyl)-3,7-dihydro- 1H-purine-2,6- dione [dasantafil, SCH-446132]; and

pharmaceutically acceptable salts and solvates thereof.

The suitability of any particular PDE5 inhibitor can be readily determined by evaluation of its potency and selectivity using literature methods followed by evaluation of its toxicity, absorption, metabolism, pharmacokinetics, etc in accordance with standard pharmaceutical practice.

Preferably, the PDE5 inhibitors have an IC50 at less than 100 nanomolar, more preferably, at less than 50 nanomolar, more preferably still at less than 10 nanomolar.

1C50 values for the PDE5 inhibitors may be determined using the PDE5 assay described hereinafter.

Preferably the PDE5 inhibitors used in the pharmaceutical combinations according to the present invention are selective for the PDE5 enzyme. Preferably they have a selectivity of PDE5 over PDE3 of greater than 100 more preferably greater than 300. More preferably the PDE5 inhibitor has a selectivity over both PDE3 and PDE4 of greater than 100, more preferably greater than 300. Selectivity ratios may be readily determined by the skilled person. IC50 values for the PDE3 and PDE4 enzyme may be determined using established literature methodology, see S A Ballard et al, Journal of Urology, 1998, vol. 159, pages 2164-2171 and as detailed herein after.

By cross reference herein to compounds contained in patents and patent applications which can be used in accordance with invention, we mean the therapeutically active compounds as defined in the claims (in particular of claim 1 ) and the specific examples (all of which is incorporated herein by reference).

PHARMACEUTICALLY ACCEPTABLE SALTS

Pharmaceutically acceptable salts can be formed from organic and inorganic acids, for example, acetic, propionic, lactic, citric, tartaric, succinic, fumaric, maleic, malonic, mandelic, malic, phthalic, hydrochloric, hydrobromic, phosphoric, nitric, sulfuric, methanesulfonic, naphthalenesulfonic, benzenesulfonic, toluenesulfonic, camphorsulfonic, and similarly known acceptable acids when a compound of this invention contains a basic moiety. Salts may also be formed from organic and inorganic bases, preferably alkali metal salts, for example, sodium, lithium, or potassium, when a compound of this invention contains an acidic moiety.

ASYMMETRY

The compounds of this invention may contain an asymmetric carbon atom and some of the compounds of this invention may contain one or more asymmetric centers and may thus give rise to optical isomers and diastereomers. While shown without respect to stereochemistry, the present invention includes such optical isomers and diastereomers; as well as the racemic and resolved, enantiomerically pure R and S stereoisomers; as well as other mixtures of the R and S stereoisomers and pharmaceutical acceptable salts thereof. It is recognized that one optical isomer, including diastereomer and enantiomer, or stereoisomer may have favorable properties over the other. Thus when disclosing and claiming the invention, when one racemic mixture is disclosed, it is clearly contemplated that both optical isomers, including diastereomers and enantiomers, or stereoisomers substantially free of the other are disclosed and claimed as well.

PHARMACEUTICAL COMPOSITIONS

The present invention also provides a pharmaceutical composition comprising a therapeutically effective amount of the agent of the present invention and a pharmaceutically acceptable carrier, diluent or excipient (including combinations thereof)

The pharmaceutical compositions may be for human or animal usage in human and veterinary medicine and will typically comprise any one or more of a pharmaceutically acceptable diluent, carrier, or excipient. Acceptable carriers or diluents for therapeutic use are well known in the pharmaceutical art, and are described, for example, in Remington's Pharmaceutical Sciences, Mack Publishing Co. (A. R. Gennarp edit. 1985). The choice of pharmaceutical carrier, excipient or diluent can be selected with regard to the intended route of administration and standard pharmaceutical practice. The pharmaceutical compositions may comprise as - or in addition to - the carrier, excipient or diluent any suitable binder(s), lubricant(s), suspending agent(s), coating agent(s), solubilising agent(s).

Preservatives, stabilisers, dyes and even flavouring agents may be provided in the pharmaceutical composition. Examples of preservatives include sodium benzoate, sorbic acid and esters of p-hydroxybenzoic acid. Antioxidants and suspending agents may be also used.

There may be different composition/formulation requirements dependent on the different delivery systems. By way of example, the pharmaceutical composition of the present invention may be formulated to be delivered using a mini-pump or by a mucosal route, for example, as a nasal spray or aerosol for inhalation or ingestable solution, or parenterally in which the composition is formulated by an injectable form, for delivery, by, for example, an intravenous, intramuscular or subcutaneous route. Alternatively, the formulation may be designed to be delivered by both routes.

Where the agent is to be delivered mucosally through the gastrointestinal mucosa, it should be able to remain stable during transit though the gastrointestinal tract; for example, it should be resistant to proteolytic degradation, stable at acid pH and resistant to the detergent effects of bile.

Where appropriate, the pharmaceutical compositions can be administered by inhalation, in the form of a suppository or pessary, topically in the form of a lotion, solution, cream, ointment or dusting powder, by use of a skin patch, orally in the form of tablets containing excipients such as starch or lactose, or in capsules or ovules either alone or in admixture with excipients, or in the form of elixirs, solutions or suspensions containing flavouring or colouring agents, or they can be injected parenterally, for example intravenously, intramuscularly or subcutaneously. For parenteral administration, the compositions may be best used in the form of a sterile aqueous solution which may contain other substances, for example enough salts or monosaccharides to make the solution isotonic with blood. For buccal or sublingual administration the compositions may be administered in the form of tablets or lozenges which can be formulated in a conventional manner.

For some embodiments, the agents of the present invention may also be used in combination with a cyclodextrin. Cyclodextrins are known to form inclusion and non-inclusion complexes with drug molecule's. Formation of a drug- cyclodextrin complex may modify the solubility, dissolution rate, bioavailability and/or stability property of a drug molecule. Drug-cyclodextrin complexes are generally useful for most dosage forms and administration routes. As an alternative to direct complexation with the drug the cyclodextrin may be used as an auxiliary additive, e.g. as a carrier, diluent or solubiliser. Alpha-, beta- and gamma-cyclodextrins are most commonly used and suitable examples are described in WO-A-91/11172, WO-A-94/02518 and WO-A-98/55148. In a preferred embodiment, the agents of the present invention are delivered systemically (such as orally, buccally, sublingually), more preferably orally.

Hence, preferably the agent is in a form that is suitable for oral delivery.

ADMINISTRATION

Compounds of the invention intended for pharmaceutical use may be administered as crystalline or amorphous products or may exist in a continuum of solid states ranging from fully amorphous to fully crystalline. They may be obtained, for example, as solid plugs, powders, or films by methods such as precipitation, crystallization, freeze drying, spray drying, or evaporative drying. Microwave or radio frequency drying may be used for this purpose.

They may be administered alone or in combination with one or more other compounds of the invention or in combination with one or more other drugs (or as any combination thereof). Generally, they will be administered as a formulation in association with one or more pharmaceutically acceptable excipients. The term 'excipient' is used herein to describe any ingredient other than the compound(s) of the invention. The choice of excipient will to a large extent depend on factors such as the particular mode of administration, the effect of the excipient on solubility and stability, and the nature of the dosage form.

Pharmaceutical compositions suitable for the delivery of compounds of the present invention and methods for their preparation will be readily apparent to those skilled in the art. Such compositions and methods for their preparation may be found, for example, in "Remington's Pharmaceutical Sciences", 19th Edition (Mack Publishing Company, 1995).

The compounds of the invention may be administered orally. Oral administration may involve swallowing, so that the compound enters the gastrointestinal tract, or buccal or sublingual administration may be employed by which the compound enters the blood stream directly from the mouth. Formulations suitable for oral administration include solid formulations such as tablets, capsules containing particulates, liquids, or powders, lozenges (including liquid-filled), chews, multi- and nano-particulates, gels, solid solution, liposome, films, ovules, sprays and liquid formulations.

Liquid formulations include suspensions, solutions, syrups and elixirs. Such formulations may be employed as fillers in soft or hard capsules and typically comprise a carrier, for example, water, ethanol, polyethylene glycol, propylene glycol, methylcellulose, or a suitable oil, and one or more emulsifying agents and/or suspending agents. Liquid formulations may also be prepared by the reconstitution of a solid, for example, from a sachet.

The compounds of the invention may also be used in fast-dissolving, fast- disintegrating dosage forms such as those described in Expert Opinion in Therapeutic Patents, H (6), 981-986, by Liang and Chen (2001).

For tablet dosage forms, depending on dose, the drug may make up from 1 weight % to 80 weight % of the dosage form, more typically from 5 weight % to 60 weight % of the dosage form. In addition to the drug, tablets generally contain a disintegrant. Examples of disintegrants include sodium starch glycolate, sodium carboxymethyl cellulose, calcium carboxymethyl cellulose, croscarmellose sodium, - crospovidone, polyvinylpyrrolidone, methyl cellulose, microcrystalline cellulose, lower alkyl-substituted hydroxypropyl cellulose, starch, pregelatinised starch and sodium alginate. Generally, the disintegrant will comprise from 1 weight % to 25 weight %, preferably from 5 weight % to 20 weight % of the dosage form.

Binders are generally used to impart cohesive qualities to a tablet formulation. Suitable binders include microcrystalline cellulose, gelatin, sugars, polyethylene glycol, natural and synthetic gums, polyvinylpyrrolidone, pregelatinised starch, hydroxypropyl cellulose and hydroxypropyl methylcellulose. Tablets may also contain diluents, such as lactose (monohydrate, spray-dried monohydrate, anhydrous and the like), mannitol, xylitol, dextrose, sucrose, sorbitol, microcrystalline cellulose, starch and dibasic calcium phosphate dihydrate.

Tablets may also optionally comprise surface active agents, such as sodium lauryl sulfate and polysorbate 80, and glidants such as silicon dioxide and talc. When present, surface active agents may comprise from 0.2 weight % to 5 weight % of the tablet, and glidants may comprise from 0.2 weight % to 1 weight % of the tablet.

Tablets also generally contain lubricants such as magnesium stearate, calcium stearate, zinc stearate, sodium stearyl fumarate, and mixtures of magnesium stearate with sodium lauryl sulphate. Lubricants generally comprise from 0.25 weight % to 10 weight %, preferably from 0.5 weight % to 3 weight % of the tablet. Other¹ possible ingredients include anti-oxidants, colourants, flavouring agents, preservatives and taste-masking agents.

Exemplary tablets contain up to about 80% drug, from about 10 weight % to about 90 weight % binder, from about 0 weight % to about 85 weight % diluent, from about 2 weight % to about 10 weight % disintegrant, and from about 0.25 weight % to about 10 weight % lubricant.

Tablet blends may be compressed directly or by roller to form tablets. Tablet blends or portions of blends may alternatively be wet-, dry-, or melt- granulated, melt congealed, or extruded before tabletting. The final formulation may comprise one or more layers and may be coated or uncoated; it may even be encapsulated. The formulation , of tablets is discussed in "Pharmaceutical Dosage Forms: Tablets", Vol. 1 , by H. Lieberman and L. Lachman (Marcel Dekker, New York, 1980).

Consumable oral films for human or veterinary use are typically pliable water- soluble or water-swellable thin film dosage forms which may be rapidly dissolving or mucoadhesive and typically comprise a compound of formula (I), a film-forming polymer, a binder, a solvent, a humectant, a plasticiser, a stabiliser or emulsifier, a viscosity-modifying agent and a solvent. Some components of the formulation may perform more than one function.

The compounds of the invention may be water-soluble or insoluble. A water- soluble compound typically comprises from 1 weight % to 80 weight %, more typically from 20 weight % to 50 weight %, of the solutes. Less soluble compounds may comprise a greater proportion of the composition, typically up to 88 weight % of the solutes. Alternatively, the compounds may be in the form of multiparticulate beads.

The film-forming polymer may be selected from natural polysaccharides, proteins, or synthetic hydrocolloids and is typically present in the range 0.01 to 99 weight %, more typically in the range 30 to 80 weight %.

Other possible ingredients include anti-oxidants, colorants, flavourings and flavour enhancers, preservatives, salivary stimulating agents, cooling agents, co-solvents (including oils), emollients, bulking agents, anti-foaming agents, surfactants and taste-masking agents.

Films in accordance with the invention are typically prepared by evaporative drying of thin aqueous films coated onto a peelable backing support or paper. This may be done in a drying oven or tunnel, typically a combined coater dryer, or by freeze-drying or vacuuming.

Solid formulations for oral administration may be formulated to be immediate and/or modified release. Modified release formulations include delayed-, sustained-, pulsed-, controlled-, targeted and programmed release.

Suitable modified release formulations for the purposes of the invention are described in US Patent No. 6,106,864. Details of other suitable release technologies such as high energy dispersions and osmotic and coated particles are to be found in "Pharmaceutical Technology On-line", 25(2), 1-14, by Verma et al (2001). The use of chewing gum to achieve controlled release is described in WO 00/35298. The compounds of the invention may also be administered directly into the blood stream, into muscle, or into an internal organ. Suitable means for parenteral administration include intravenous, intraarterial, intraperitoneal, intrathecal, intraventricular, intraurethral, intrastemal, intracranial, intramuscular and subcutaneous. Suitable devices for parenteral administration include needle (including microneedle) injectors, needle-free injectors and infusion techniques. Parenteral formulations are typically aqueous solutions which may contain excipients such as salts, carbohydrates and buffering agents (preferably to a pH of from 3 to 9), but, for some applications, they may be more suitably formulated as a sterile non-aqueous solution or as a dried form to be used in conjunction with a suitable vehicle such as sterile, pyrogen-free water. The preparation of parenteral formulations under sterile conditions, for example, by lyophilisation, may readily be accomplished using standard pharmaceutical techniques well known to those skilled in the art.

The solubility of compounds of formula (I) used in the preparation of parenteral solutions may be increased by the use of appropriate formulation techniques, such as the incorporation of solubility-enhancing agents. Formulations for parenteral administration may be formulated to be immediate and/or modified release. Modified release formulations include delayed-, sustained-, pulsed-, controlled-, targeted and programmed release. Thus compounds of the invention may be formulated as a solid, semi-solid, or thixotropic liquid for administration as an implanted depot providing modified release of the active compound. Examples of such formulations include drug- coated stents and poly(c//-lactic-coglycolic)acid (PGLA) microspheres.

The compounds of the invention may also be administered topically to the skin or mucosa, that is, dermally or transdermally. Typical formulations for this purpose include gels, hydrogels, lotions, solutions, creams, ointments, dusting powders, dressings, foams, films, skin patches, wafers, implants, sponges, fibres, bandages and microemulsions. Liposomes may also be used. Typical carriers include alcohol, water, mineral oil, liquid petrolatum, white petrolatum, glycerin, polyethylene glycol and propylene glycol. Penetration enhancers may be incorporated - see, for example, J Pharm Sci, 88 (10), 955-958, by Finnin and Morgan (October 1999). Other means of topical administration include delivery by electroporation, iontophoresis, phonophoresis, sonophoresis and microneedle or needle-free (e.g. Powderject™, Bioject™, etc.) injection. Formulations for topical administration may be formulated to be immediate and/or modified release. Modified release formulations include delayed-, sustained-, pulsed-, controlled-, targeted and programmed release.

The compounds of the invention can also be administered intranasally or by inhalation, typically in the form of a dry powder (either alone, as a mixture, for example, in a dry blend with lactose, or as a mixed component particle, for example, mixed with phospholipids, such as phosphatidylcholine) from a dry powder inhaler or as an aerosol spray from a pressurised container, pump, spray, atomiser (preferably an atomiser using electrohydrodynamics to produce a fine mist), or nebuliser, with or without the use of a suitable propellant, such as 1 ,1 ,1 ,2-tetrafluoroethane or 1 ,1 ,1 ,2,3,3,3- heptafluoropropane. For intranasal use, the powder may comprise a bioadhesive agent, for example, chitosan or cyclodextrin.

The pressurised container, pump, spray, atomizer, or nebuliser contains a solution or suspension of the compound(s) of the invention comprising, for example, ethanol, aqueous ethanol, or a suitable alternative agent for dispersing, solubilising, or extending release of the active, a propellant(s) as solvent and an optional surfactant, such as sorbitan trioleate, oleic acid, or an oligolactic acid.

Prior to use in a dry powder or suspension formulation, the drug product is micronised to a size suitable for delivery by inhalation (typically less than 5 microns). This may be achieved by any appropriate comminuting method, such as spiral jet milling, fluid bed jet milling, supercritical fluid processing to form nanoparticles, high pressure homogenisation, or spray drying. Capsules (made, for example, from gelatin or hydroxypropylmethylcellulose), blisters and cartridges for use in an inhaler or insufflator may be formulated to contain a powder mix of the compound of the invention, a suitable powder base such as lactose or starch and a performance modifier such as /-leucine, mannitol, or magnesium stearate. The lactose may be anhydrous or in the form of the monohydrate, preferably the latter. Other suitable excipients include dextran, glucose, maltose, sorbitol, xylitol, fructose, sucrose and trehalose.

A suitable solution formulation for use in an atomiser using electrohydrodynamics to produce a fine mist may contain from 1 μg to 20mg of the compound of the invention per actuation and the actuation volume may vary from 1 μl to 100μl. A typical formulation may comprise a compound of formula (I), propylene glycol, sterile water, ethanol and sodium chloride. Alternative solvents which may be used instead of propylene glycol include glycerol and polyethylene glycol.

Suitable flavours, such as menthol and levomenthol, or sweeteners, such as saccharin or saccharin sodium, may be added to those formulations of the invention intended for inhaled/intranasal administration.

Formulations for inhaled/intranasal administration may be formulated to be immediate and/or modified release using, for example, PGLA. Modified release formulations include delayed-, sustained-; pulsed-, controlled-, targeted and programmed release.

In the case of dry powder inhalers and aerosols, the dosage unit is determined by means of a valve which delivers a metered amount. Units in accordance with the invention are typically arranged to administer a metered dose or "puff' containing from 2 to 30mg of the compound of formula (I). The overall daily dose will typically be in the range 50 to 100mg which may be administered in a single dose or, more usually, as divided doses throughout the day. The compounds of the invention may be administered rectally or vaginally, for example, in the form of a suppository, pessary_s or enema. Cocoa butter is a traditional suppository base, but various alternatives may be used as appropriate. Formulations for rectal/vaginal administration may be formulated to be immediate and/or modified release. Modified release formulations include delayed-, sustained-, pulsed-, controlled-, targeted and programmed release.

The compounds of the invention may also be administered directly to the eye or ear, typically in the form of drops of a micronised suspension or solution in isotonic, pH-adjusted, sterile saline. Other formulations suitable for ocular and aural administration include ointments, biodegradable (e.g. absorbable gel sponges, collagen) and non-biodegradable (e.g. silicone) implants, wafers, lenses and particulate or vesicular systems, such as niosomes or liposomes. A polymer such as crossed-linked polyacrylic acid, polyvinylalcohol, hyaluronic acid, a cellulosic polymer, for example, hydroxypropylmethylcellulose, hydroxyethylcellulose, or methyl cellulose, or a heteropolysaccharide polymer, for example, gelan gum, may be incorporated together with a preservative, such as benzalkonium chloride. Such formulations may also be delivered by iontophoresis. Formulations for ocular/aural administration may be formulated to be immediate and/or modified release. Modified release formulations include delayed-, sustained-, pulsed-, controlled-, targeted, or programmed release.

The compounds of the invention may be combined with soluble macromolecular entities, such as cyclodextrin and suitable derivatives thereof or polyethylene glycol-containing polymers, in order to improve their solubility, dissolution rate, taste-masking, bioavailability and/or stability for use in any of the aforementioned modes of administration. Drug-cyclodextrin complexes, for example, are found to be generally useful for most dosage forms and administration routes. Both inclusion and non-inclusion complexes may be used. As an alternative to direct complexation with the drug, the cyclodextrin may be used as an auxiliary additive, i.e. as a carrier, diluent, or solubiliser. Most commonly used for these purposes are alpha-, beta- and gamma- cyclodextrins, examples of which may be found in International Patent Applications Nos. WO 91/11172, WO 94/02518 and WO 98/55148.

The compositions of the present invention may be administered by direct injection.

For some applications, preferably the agent is administered orally.

A particular advantage, especially of compounds of formulae (I), (II) and (III) above is that they are active orally.

For some applications, preferably the agent is administered topically.

DOSE LEVELS

Typically, a physician will determine the actual dosage which will be most suitable for an individual subject. The specific dose level and frequency of dosage for any particular individual may be varied and will depend upon a variety of factors including the activity of the specific compound employed, the metabolic stability and length of action of that compound, the age, body weight, general health, sex, diet, mode and time of administration, rate of excretion, drug combination, the severity of the particular condition, and the ^• individual undergoing therapy. The agent and/or the pharmaceutical composition of the present invention may be administered in accordance with a regimen of from 1 to 10 times per day, such as once or twice per day.

For oral and parenteral administration to humans, the daily dosage level of the agent may be in single or divided doses.

Depending upon the need, the agent may be administered at a dose of from 0.01 to 30 mg/kg body weight, such as from 0.1 to 10 mg/kg, more preferably from 0.1 to 1 mg/kg body weight. Naturally, the dosages mentioned herein are exemplary of the average case. There can, of course, be individual instances where higher or lower dosage ranges are merited. Preferably, the daily oral dose is from 0.1 to 100 mg. More preferably, the daily dose is from 0.5 to 20 mg. Still more preferably, the daily dose is from 1 to 10 mg. Still more preferably, the daily dose is 2 to 5 mg. Most preferably, the daily dose is about 3 mg.

Suitable doses will include those which allow a satisfactory therapeutic ratio between the treatment of female sexual dysfunction, particularly FSAD, and the induction of emesis or other side effects.

FORMULATION

The agents of the present invention may be formulated into a pharmaceutical composition, such as by mixing with one or more of a suitable carrier, diluent or excipient, by using techniques that are known in the art.

The following present some non-limiting examples of formulations.

Formulation 1 : A tablet is prepared using the following ingredients:

weight/m g

Agent 250

Cellulose, microcrystalline 400

Silicon dioxide, fumed 10

Stearic acid 5

Total 665

the components are blended and compressed to form tablets each weighing 665mg.

Formulation 2: An intravenous formulation may be prepared as follows: Agent 100mg

Isotonic saline 1 ,000ml

INDIVIDUAL

As used herein, the term "individual" refers to vertebrates, particularly members of the mammalian species. The term includes but is not limited to domestic animals, sports animals, primates and humans.

The compounds of the invention find application in the following sub- populations of patients with FSD: the young, the elderly, pre-menopausal, peri-menopausal, post-menopausal women with or without hormone replacement therapy.

It is to be appreciated that all references herein to treatment include curative, palliative and prophylactic treatment.

The compounds of the invention find application in patients with FSD arising from:-

i) Vasculogenic etiologies e.g. cardiovascular or atherosclerotic diseases, hypercholesterolemia, cigarette smoking, diabetes, hypertension, radiation and perineal trauma, traumatic injury to the iliohypogastric pudendal vascular system;

ii) Neurogenic etiologies such as spinal cord injuries or diseases of the central nervous system including multiple sclerosis, diabetes, Parkinsonism, cerebrovascular accidents, peripheral neuropathies, trauma or radical pelvic surgery;

iii) Hormonal/endocrine etiologies such as dysfunction of the hypothalamic/pituitary/gonadal axis, or dysfunction of the ovaries, dysfunction of the pancreas, surgical or medical castration, androgen deficiency, high T/IB2007/003884

58 circulating levels of prolactin e.g. hyperprolactinemia, natural menopause, premature ovarian failure, hyper and hypothyroidism;

iv) Psychogenic etiologies such as depression, obsessive compulsive disorder, anxiety disorder, postnatal depression/"Baby Blues", emotional and relational issues, performance anxiety, marital discord, dysfunctional attitudes, sexual phobias, religious inhibition or a traumatic past experiences; and/or

v) Drug-induced sexual dysfunction resulting from therapy with selective serotonin reuptake inhibitors (SSRis) and other antidepressant therapies (tricyclics and major tranquillizers), anti-hypertensive therapies, sympatholytic drugs, chronic oral contraceptive pill therapy.

BIOAVAILABILITY

Preferably, the compounds of the invention (and combinations) are orally bioavailable. Oral bioavailablity refers to the proportion of an orally administered drug that reaches the systemic circulation. The factors that determine oral bioavailability of a drug are dissolution, membrane permeability and metabolic stability. Typically, a screening cascade of firstly in vitro and then in vivo techniques is used to determine oral bioavailablity.

Dissolution, the solubilisation of the drug by the aqueous contents of the gastro-intestinal tract (GIT), can be predicted from in vitro solubility experiments conducted at appropriate pH to mimic the GIT. Preferably the compounds of the invention have a minimum solubility of 50 mcg/ml. Solubility can be determined by standard procedures known in the art such as described in Adv. Drug Deliv. Rev. 23, 3-25, 1997.

Membrane permeability refers to the passage of the compound through the cells of the GIT. Lipophilicity is a key property in predicting this and is defined by in vitro Log D_7-4 measurements using organic solvents and buffer. Preferably the compounds of the invention have a Log D₇.₄ of -2 to +4, more preferably -1 to +2. The log D can be determined by standard procedures known in the art such as described in J. Pharm. Pharmacol. 1990, 42:144.

Cell monolayer assays such as CaCO₂ add substantially to prediction of favourable membrane permeability in the presence of efflux transporters such as p-glycoprotein, so-called caco-2 flux. Preferably, compounds of the invention have a caco-2 flux of greater than 2x10^'6cms^"1, more preferably greater than 5x10^"6cms^"1. The caco flux value can be determined by standard procedures known in the art such as described in J. Pharm. Sci, 1990, 79, 595-600

Metabolic stability addresses the ability of the GIT or the liver to metabolise compounds during the absorption process: the first pass effect. Assay systems such as microsomes, hepatocytes etc are predictive of metabolic liability. Preferably the compounds of the Examples show metabolic stability in the assay system that is commensurate with a hepatic extraction of less then 0.5. Examples of assay systems and data manipulation are described in Curr. Opin. Drug Disc. Devel., 201 , 4, 36-44, Drug Met. Disp.,2000, 28, 1518-1523.

Because of the interplay of the above processes further support that a drug will be orally bioavailable in humans can be gained by in vivo experiments in animals. Absolute bioavailability is determined in these studies by administering the compound separately or in mixtures by the oral route. For absolute determinations (% absorbed) the intravenous route is also employed. Examples of the assessment of oral bioavailability in animals can be found in Drug Met. Disp.,2001 , 29, 82-87; J. Med Chem , 1997, 40, 827-829, Drug Met. Disp.,1999, 27, 221-226.

Preferred features of each aspect of the present invention are as for each of the other aspects mutatis mutandis.

PROTOCOLS PROTOCOL 1 : PROTOCOL FOR DETERMINING MQR ANTAGONIST ACTIVITY

mu FLIPR Protocol:

Transient Co-transfection Protocol (PER PLATE) Cell Line: Hek293T

HOPM Complete Media: for 1 Liter

DMEM

100 mL heat inactivated FBS

10 mL L-glutamine

1O mL Pen/Strep

10 mL Geneticin G418

Seeding

7 x e6 cells are seeded into a T-175 one day prior to transfection.

Cell Preparation

Harvest cells from a 60% confluent T-175 with 2 mL of 0.25% trypsin.

Let trypsin sit in flask for approximately 5 minutes.

Bang the flask once and resuspend cells in 8 mL of complete medium.

Pipet suspension up and down several times and transfer to a 50 mL polypropylene tube.

Spin down cells at 1 ,000 rpm for 5 minutes.

Decant supernate and resuspend in 15 mL of complete medium.

Count cells to obtain a cell density of 4 x e5 cells / mL. Dilute cells if necessary in a final volume of 15 ml_ of complete medium.

Transfection Mix

Set up 2 polypropylene 14 ml_ tubes.

Add 1 ml_ of DMEM serum free media and 70 ml_ of Fugene 6 reagent to the first tube.

Add 1.84 mg of HOPM DNA, 1.6 mg of Gql5 and 10 mg of pcDNA to the second tube.

Incubate for 5 minutes at room temperature.

Add the DMEM/Fugene mix to the DNA drop by drop and swirl gently.

Let the mixture incubate for 20 minutes at room temperature.

Add the mixture in a dropwise fashion to the cell suspension.

Mix slowly by gently inverting the tube several times.

Add 130 mL per well into Black/Clear Poly-d-Lysine coated FLIPR plates.

Place in 37°C incubator for 48 hours.

Assay Reagents:

Assay Buffer 1 Liter pH 7.4

Reagent Cone. (mM) Amount (g)

NaCL 145 8.47 glucose 10 1.80

KCI 5.0 0.37 tfgSO4 1.0 0.25

HEPES 10 2.38

Calcium 2.0 0.22

Probenicid Mixture

Probenecid 0.74g

5N NaOH 1 ml_

Assay Buffer 9 mL

Cell Dye Media PER PLATE

DMEM 11 mL

Probenicid Mixture 11O mL

Fluo 4 Dye 2 vials add to dye vial:

Pluoronic Acid 22 mL

DMSO 22 mL

Assay Protocol:

Cell plates are loaded with dye one hour prior to assay, and incubated in a non-sterile incubator at 37°C. Excess dye is flicked out, and plates washed with assay buffer in the Skatron plate washer.

Cells are allowed to equillibrate for 20-30 minutes.

Using the FLIPR 384, drug is added in the initial addition and monitored at 2 second intervals for 2 minutes.

Plates are pre-incubated with drug for 20 minutes.

Second addition is agonist competitor (40OnM DAMGO) which is added and monitored at 2 second intervals for 2 minutes. Data are analyzed using Excel and Graph Pad.

INTERPRETATION

Data are interpreted by characterizing the functional activity of compounds as antagonists or agonists.

PROTOCOL 2: Human Delta Opioid Receptor Competition Binding Protocol (using ³H-NALTRINDOLE)

3H-NALTRINDOLE BINDING ASSAY

MATERIALS AND EQUIPMENT:

ASSAY BUFFER-50mM Tris HCI pH 7.4, 5mM MgCI2, 100ug/ml Bacitracin, 1.08ug/ml Bestatin, and 0.3uM Thiorphan (at room temp.).

Polypropylene 96 well plates.

3H-Natrindole, NEN, NET-1065, 32Ci/mmol, or Tocris Cookson, R740, 50Ci/mmol, ~0.5nM.

CHO cells expressing human opioid receptor (HOPD).

Membrane buffer 5OmM Tris HCI pH 7.4 and 1 mM EGTA.

Brinkmann PT3000 Polytron.

Wash buffer -5OmM Tris HCI, and 5mM MgCI2, pH 7.4 (at 4 deg C).

Skatron Harvester.

Whatman GF/C glass fiber filters polyethylenimine (PEI). Cell Membrane Preparation

Dislodge the HOPD cells from the bottom of the flask using D-PBS with 5mM EDTA at 37 ⁰C. Spin the dislodged cells at 18,000 rpm for 15 min in a SS-34 rotor in a SORVALL centrifuge. Resuspend the pellet in 50 vols of membrane buffer (5OmM Tris HCI pH 7.4, & 1mM EGTA) using a Polytron at 15,000 rpm for 20 sec. Spin as above and resuspend pellet to a final concentration of 10ug per well (0.4mg/mI stock).

Binding Assay

Incubation Mixture: 25μl Total, compound (at 10X), or blank 200μl 3H-NTI (-0.5 nM final concentration) 25μl Cell membranes (~10ug protein/well).

The reaction is initiated with the addition of cell membranes to each well of a polypropylene 96-well plate containing 3H-NTI and the appropriate blank, competitor, or vehicle. Non-specific binding is estimated using 1uM cold Naltrindole. Incubate for 90 min at 37 °C. The reaction is terminated by rapid filtration onto Whatman GF/C filters (presoaked in 0.6% PEI for at least 1 hour) using a Skatron Green Machine harvester at program 555. The filter disks are airdried overnight, then placed in sample bags and counted on a Betaplate counter.

INTERPRETATION

Data are expressed as Ki's (the concentration that occupies half of the receptors). If a Ki is not obtained from the assay, the inhibition at the highest dose tested is reported. All data are analyzed using linear regression with a Quickbasic Beta software program.

PROTOCOL 3: Kappa Opioid receptor binding protocol CHO-K1 cells expressing the Human kappa opioid receptor are purchased as a membrane preparation from Receptor Biology. A 400 microassay vial (1 ml_ volume) is thawed and added to 79ml_s of assay buffer (5OmM Tris HCL, pH 7.4, 1 OmM MgCL2) and homgenized with a Polytron. Tissue is kept on ice. Compounds are solubilized into 100% DMSO and diluted into assay buffer. Blank is 10μM Naloxone; ligand is 2nM 3H Diprenorphine (NEN #NET1121). 25μL of compound, buffer or blank is added to a 96well polypropylene plate, followed by 25 μl_ of 3H DPN and 20OuL of membranes. Plate is incubated at room temperature on an orbital shaker for 1 hour. Assay is then harvested on to a VVallac printed filtermat A previously soaked in 0.5% PEI using a Skatron harvester and 5OmM Tris HCL pH 7.4 as the wash buffer. Filters are allowed to dry overnight then counted the next day with a Betaplate counter and later analyzed.

INTERPRETATION

Data are analyzed using Excel to determine IC₅₀ and Ki values.

PROTOCOL 4: GTPYS ANTAGONIST BINDING IN FLASHPLATES FOR MU & DELTA & KAPPA

Specific Activity of GTPγS is 1100-1200 Ci/mmole. Use radioactivity calculator at http://www.graphpad.com to determine actual concentration of stock. The final concentration of GTPy ³⁵S is 0.1 nM, (stock 0.4 nM, 4X).

Plate set up:

-add 2 μl 100X compound to plate. Final concentrations in assay plate are 10^" ⁵ to 10-¹⁰

- controls should include 2 μl cold 1 mM GTPγS (non-specific), 2 μl DMSO buffer (total) and 2 μl DMSO (basal, no agonist)

-add 50 μl 0.4 nM GTPγS to all wells

-add 128 μl homogenized membrane (5 μg) in assay buffer to all wells

(homogenize membranes in a dounce)

-shake briefly

-incubate 10 min (S) 3O⁰C

-add 20 μl 10 uM b-endorphin to mu or 10 nM BW373U86 delta or 100 nM dynorphinA to kappa in assay buffer to all wells except basal (add 20 μl buffer)

-shake briefly

-incubate 60 min @ 3O⁰C

-spin 10 min @ 1000 X G (2500 rpm)

-count

100X Protease inhibitors: 10 mg/ml bacitracin 10 mg/ml benzamidine 0.5 mg/ml aprotinin 0.5 mg/ml leupeptin

Notes:

- make assay buffer fresh - keep assay buffer at RT during experiment

- make protease inhibitors at 100X concentration and store at - 20⁰C

EXAMPLES

Example 1

Binding Studies: Selective Affinity of Compound A for Mu Opioid Receptors

The affinity and selectivity of Compound A binding to the mu, delta, and kappa opioid receptor subtypes were evaluated in radioligand binding studies. The affinity of Compound A for the mu opioid receptor was determined using a membrane preparation from Chinese Hamster Ovary (CHO) cells stably expressing the human mu opioid receptor. Compound A displaced the binding of [³H]DAMGO to the human mu receptor with a Kj value of 0.88+0.22 nM). A similar Kj value of 0.76±0.19 nM was obtained against the rodent mu receptor (data not shown).

Figure 1 shows displacement by Compound A of [³H]DAMGO (Mu Receptors), [³H]Naltrindole (Delta Receptors) and [³H]Diprenorphine (Kappa Receptors) from binding to their respective human opioid receptor. Affinity for the delta receptor was determined using CHO cells expressing human delta opioid receptors. Compound A displaced the binding of [³H]naltrindole with a K₁ value of 2510+578 nM.

Characterization of the binding of Compound A to the kappa receptor utilized HEK-T293 cells stably expressing the human kappa receptor. In membrane binding studies, Compound A displaced the binding of [³H]diprenorphine with a Kj value of 353+140 nM.

In vitro Studies on the Functional Activity of Compound A at Mu and Kappa Opioid Receptors

Binding studies indicate the affinity with which a compound binds to a recognition site, but are of limited use for understanding its functional effects. Additional in vitro studies were carried out with Compound A to evaluate its functional activity at mu and kappa receptors transiently expressed in CHO cells.

All three opioid receptors normally interact with heterotrimeric G-proteins, in particular Gi and G₀. These proteins negatively couple the opioid receptors to adenyl cyclase such that activation of the opioid receptors leads to a reduction in cAMP concentrations that is often difficult to detect. However, using HEK cells transiently expressing both the mu opioid receptor and a chimeric G-protein results in mobilization of intracellular Ca⁺⁺ stores. Using a fluorescence imaging plate reader (FLIPR) alterations in intracellular Ca⁺⁺ concentrations are imaged in real time using changes in fluorescence of Fluo- 4.

The DAMGO-elicited increase in the intracellular concentration of Ca⁺⁺ was dose-dependently inhibited by Compound A, with a Ki value of 2.9+1.5 nM (N = 4). In contrast, Compound A antagonized the increase in intracellular Ca⁺⁺ elicited by U-50,488, a kappa receptor selective agonist, with an Kj value of 72.8±28 nM (N = 4; Figure 2).

Figure 2 shows inhibition by Compound A of the Increase in the Intracellular Ca⁺⁺ in CHO Cells Transiently Transfected with the Mu Receptor (Squares) 4

69 and G_αQj₅ G-Protein or with the Kappa Receptor (Circles) and G_αQj₅DAMGO (400 nM) was the agonist used to stimulate the mu receptor and U-50,488 (400 nM) to activate the kappa receptor. Representative curves from triplicate measurements.

Table 1 summarizes the key pharmacologic properties of Compound A.

Table 1. Summary of Key Pharmacologic Properties of Compound A

Assay Result

Receptor binding studies

Compound A Mu Receptor Ki = 0.88±0.22 nM (0.3745 ng/mL) Delta Receptors Kj = 2510±578 nM (1070.7 ng/mL) Kappa Receptor Ki = 353±140 nM (150.6 ng/mL)

Naltrexone Mu Receptor K₁ = 0.4±0.05 nM (0.136 ng/mL) Delta Receptors Ki = 29.6±6.4 nM (10.1 ng/mL) Kappa Receptor K, = 5.4±2.3 nM (1.84 ng/mL)

In vitro studies

FLIPR (Ki) mu K, = 2.9±1.5 nM (1.19 ng/mL) kappa Ki = 72.8±28 nM (31 ng/mL)

Example 2

Animal husbandry

Rats were maintained on a light reversed cycle (dark from 09:00-21:00 hrs) for a minimum of three weeks prior to each study. During this period animals were single-sexed housed in groups of five with food and water available ad libitum. All behavioural tests were carried out between 12:00-17:00hrs (during the dark period) under half lux lighting conditions.

Experiments were in compliance with UK legislation and subject to local ethical review. A - The receptivity model.

Tests were carried out in separate circular Perspex arenas approximately 50cm in diameter. A test female was placed into the arena containing a sexually experienced active male rat. The male was allowed to mount the test females 10 times and the number of sexual behaviours were scored.

Treatment of test females

Forty-eight hours prior to study day the test females were dosed with 5 μg/rat estrogen SC. On the day of the test the test females were dosed with progesterone (50 μg/rat SC) and pre-tested 3-4 hours later to establish their pre-dose lordosis quotients and receptivity scores. They were then dosed with either test compound (Compound A) PO, test compound vehicle (de- ionized water (5 mL/kg PO), internal standard naloxone hydrochloride (2 mg/kg SC) or internal standard vehicle (saline 0.9% w/v 1 mL/kg SC).

Hormone replacement therapy (HRT) animals serve as a positive control and are primed as such to bring them into full behavioural estrous, displaying maximal receptive and proceptive behaviours. HRT animals received 5 μg/rat estrogen SC forty-eight hours prior to study day and 1 mg/kg progesterone on study day, however no pre-test was conducted.

All females dosed with either Compound A or de-ionized water were tested at 60 and 120 minutes post dose.

Females dosed with naloxone hydrochloride or saline were tested at 30 minutes post dose.

Scoring methodology Receptivity was assessed using the lordosis quotient, in which the frequency of female lordosis (a dorsiflexion that allows/is necessary for intromission (vaginal penetration) to occur) is scored as a ratio of 10 mounts by a sexually active male rat and expressed as a percentage.

Receptivity was also assessed using the receptivity score (RS) which incorporates other behaviours in addition to lordosis in response to a male mount.

Criteria for scores

0 is assigned when a female rears and rejects e.g. active avoidance behaviours such as boxing and kicking in response to a mount;

1 is assigned when a male is allowed to mount with or without intromission but the female does not display the lordotic posture and either remains stationary or moves away;

2 is assigned when the male mounts the female with or without intromission but forces the female into a lordotic posture. The lordotic response is not full;

3 is assigned when the male is allowed to mount with or without intromission and the female remains stationary during the interaction whilst displaying a full lordotic posture;

Behavioural outcomes were scored in response to ten mounts using the above criteria. A mean receptivity score was calculated for each rat by summing the score for each mount and then dividing by the number of mounts i.e. 10.

Statistics and Data analysis

Calculation of receptivity score and lordosis quotient Receptive behaviours were scored and tallied on score sheets using the above criteria. Data from these sheets were transferred to an Excel spreadsheet. Excel was used to calculate the lordosis quotient per rat on each dose of Compound A, de-ionized water (5 mL/kg), naloxone hydrochloride and saline (0.9% w/v 1 mL/kg) by dividing the number of lordotic responses out of ten mounts multiplied by 100.

Lordosis quotient (LQ) = ((number of lordotic responses/10)* 100.

Excel was also used to calculate the mean receptivity score per rat on each dose of Compound A, de-ionized water (5 mL/kg), naloxone hydrochloride and saline (0.9% w/v 1 mL/kg) using the following formula:

Mean receptivity score = Σ behavioural score * (frequency of behavioural response/10)

The calculated lordosis quotients and receptivity scores were then averaged per treatment group and used to generate a mean receptivity score and lordosis quotient per treatment group and standard error of the mean (SEM). These data were used to generate graphs of mean lordosis quotient and receptivity scores per treatment group at pre-test and 120 minutes post dose.

Statistical analysis was done using Analysis of Variance (ANOVA) package from Excel add-in LabStats (Tessella). The non-clinical statistics group recommended a number of different statistical methods to analyze the data including ANOVA, paired and un-paired t-tests.

Exclusion criteria

Animals which were deemed over or under receptive at pre-test were excluded from analysis. Under receptive animals did not display the minimal receptive behaviour expected of the combined estrogen-progesterone prime from previous studies. Therefore they were deemed unlikely improvers and did not show any improvement upon intervention with study compounds since they had responded poorly even to the hormonal prime. The minimum acceptable receptivity score for inclusion in the study was > 0.6. Over receptive animals displayed more than acceptable receptive behaviour than was expected of the combined estrogen-progesterone prime based on previous studies. They were also deemed unlikely improvers since there was a reduced window of opportunity to show any improvement upon intervention with compounds. They were likely to result in false positives due to their increased sensitivity to the hormonal prime. The maximum acceptable receptivity score and lordosis quotient for inclusion in the study was ≤ 1.6 and ≤ 50% respectively.

> 0.6 acceptable range for receptivity score < 1.6 acceptable range for lordosis quotient < 50%

Previous priming and proof of concept studies have been used to observe the typical sexual and non-sexual behaviour of females which had received the combined estrogen-progesterone prime. Females which deviated from the normal behavior both sexually (over and under receptive animals - defined by the parameters above) and non-sexually (i.e. females which displayed stress or anxiety behaviours e.g. sitting immobile and hunched in one comer) were excluded from the study - they were clear outliers. This study was not designed to pick up such behaviours, therefore this exclusion criterion was qualitative and not a measured phenomenon. (Approval from non-clinical statistics as a means of working from a defined population).

Analysis of receptivity score

ANOVA was used to analyze the receptivity score using the pre-test scores as a covariate. The receptivity score pre-test values (i.e. before dosing with Compound A, naloxone hydrochloride and their respective vehicles) assumed a normal distribution which was the basis of using ANOVA. However, after dosing with Compound A, naloxone hydrochloride or their respective vehicles, the variances of the treatment groups became unequal. ANOVA assumes a normal distribution of values and equal variance between treatment groups which is not the case in this study.

In addition to ANOVA, paired t-tests comparing the treatment group post-dose receptivity scores at eaςh test time point versus (VS) their own pre-test receptivity scores were also used. Un-paired t-tests comparing Compound A and naloxone hydrochloride receptivity scores VS their respective vehicles at each test time point were also applied. The statistical outcomes from these t- tests were not dissimilar to ANOVA. However, as the t-tests used multiple comparisons there was a greater risk of statistical error and therefore it was felt that the results from ANOVA were more robust.

Analysis of lordosis quotient

ANOVA was used to analyze the lordosis quotient using the pre-test LQs as a covariate. The pre-test lordosis quotients assumed a skewed distribution and unequal variance between treatment groups. Additionally there were a high proportion of zero lordotic responses. ANOVA assumes a normal distribution and equal variance and additionally is not very robust with data containing a high proportion of zeros. The scoring for lordosis quotient is categorical or count data however there is no consensus on the most appropriate method to analyze lordosis quotients.

Materials:

Test Substances

Compound A (Mesylate salt). MW 522.69

Naloxone hydrochloride (Sigma) Lot number 064K0687, Product number

N7758. MW 399.87

Steroidal hormones β-Estradiol 3-Benzoate (Sigma) Lot number 013K0586, Product number

E8515. MW 376.49

Progesterone (Organics) Lot number A0222735. MW 314.46

Dose preparation of test compounds

Compound A was dissolved in de-ionized water to make a stock solution of 20.3 mg/5mL (194nM) (equivalent to top dose 16.7 mg/kg multiplication by 1.22 correction factor due to salt). De-ionized water was used as a diluent to make up subsequent dilutions.

Naloxone hydrochloride was dissolved in saline (0.9% w/v 1 mL/kg) and made up 30 min before use.

Dose Preparation of steroidal hormones

The β-Estradiol 3-Benzoate stock solution for 20μg/rat prime was prepared as 100μg/ml (0.266 nM) in corn oil. Corn oil was used as a diluent to make up subsequent dilutions.

The progesterone stock solution for 1000μg/rat prime was prepared as 5000μg/ml (15.9 nM) in corn oil. Corn oil was used as a diluent to make up subsequent dilutions.

Dose Levels

Compound A: 0.00167, 0.0167, 0.5, 1.67, 5 and 16.7 mg/kg (194nM) administered orally (PO).

Naloxone hydrochloride: 2 mg/kg (5nM) administered subcutaneously (SC).

β-Estradiol 3-Benzoate: 5μg/rat administered subcutaneously (SC). Progesterone: 50 μg/rat and 1 mg/rat administered subcutaneously (SC).

Dose Volume

Compound A: 5 mL/kg Naloxone hydrochloride: 1 mL/kg β-Estradiol 3-Benzoate: 0.2 ml/rat Progesterone: 0.2ml/rat

Vehicle

Compound A: de-ionized water Naloxone hydrochloride: saline (0.9% w/v) β-Estradiol 3-Benzoate: com oil Progesterone: corn oil

RESULTS

Compound A caused a statistically significant increase in the receptivity score at doses 0.5 (p=0.0049), 1.67 (p=0.021 ), 5 (p=0.0002) and 10 (p=0.01 ) mg/kg compared to vehicle at 120 minutes post dose (Figure 3).

Summary figure (Figure 3) showing the mean receptivity score at pre-test and 120 minutes post-dose, calculated as one mean for each animal on each dose of either Compound A or de-ionized water (Compound A vehicle).

In addition, as shown in Figure 4, Compound A caused a statistically significant increase in the lordosis quotient at doses 0.0167 (p=0.029), 0.5 (p=0.041), 1.67 (p=0.065), 5 (p=0.0003) and 16.7 .(p=0.0025) mg/kg compared to vehicle at 120 minutes post dose (Figure 4).

Therefore, Compound A enhances the receptive behaviour of female rats. B - The proceptivity model

The treatment of test animals was the same as that for the receptivity model described above.

Proceptivity was assessed by counting ear wiggles. Ear wiggling is a rapid vibration of the ears, associated with an increase in prosexual proceptive behaviour akin to sexual desire and interest.

Ear wiggles were counted at 120 minutes post dose for Compound A (0.00167-T6.7mg/kg)PO. Ear wiggle scores were used to generate a mean ear wiggle score per treatment group and standard error^' of the mean (SEM). This data was used to generate a graph of mean ear wiggles score per treatment at 120 minutes post dose compared to vehicle.

The materials used, including dose preparation and dose levels, were the same as for the receptivity model described above.

Results

Compound A caused a significant increase in the mean number of ear wiggles at doses 0.0167, 0.5, 1.67, 5 and 16.7 mg/kg compared to vehicle at 120 minutes post dose (Figure 5). Thus, Compound A enhances proceptive behaviours in female rats.

Conclusions

In view of the effectiveness of Compound A in enhancing proceptive and receptive behaviours in female rats, it can be concluded that Compound A and other selective mu opioid receptors antagonists find use in the treatment and/or prevention of female sexual dysfunction (FSD).

Example 3 A clinical study with a suitable selective mu opioid receptor antagonist, e.g. -Ξxo-N-{3-[6-ethyl-3-(2-hydroxy-indan-2-ylmethyl)-3-aza-bicyclo[3.1.0]hex-6- yl]-pheny!} methanesulfonamide (mesylate salt) or Compound A, can be carried out following protocols similar to those for published studies with sildenafil (Caruso, S. et al (2001) BJOG 108,623-628; Berman, JR et al (2001) J Sex Marital Ther 27, 411-420).

Briefly, women with FSAD are given a suitable dose of the compound or a placebo. The skilled person will be able to determine a suitable dose for the compound to be used; for the two compounds mentioned above, a dose range of 0.1 to 50 mg could be used. The study can be run for a suitable period, such as, for example, six weeks.

The women are healthy pre-menopausal women of 20 years — 45 years and who are on stable use of oral contraceptives. Women with any other significant disease causing female sexual dysfunction, women on drugs known to cause female sexual dysfunction and women who have given birth in the 12 months preceding the study or are planning to become pregnant during the study are excluded.

Evaluation of the efficacy of the treatment can be carried out by physiologic measurements in the clinic (e. g. measuring clitoral, labial (vestibular bulb), urethral, and vaginal arterial peak systolic velocity and end diastolic velocity using duplex Doppler ultrasonography; vaginal pH using a digital pH meter, maximum intravaginal pressure/volume changes using commercially available compliance balloons, vibratory perception thresholds recorded from the clitoris and the mucosal aspects of the right and left labia minora using a standard biothesiometer), as well as by questionnaire, diary events, assessing and quantifying, e.g. subjective arousal, orgasm, enjoyment, number of satisfactory sexual experiences, sexual frequency, and number of sexual fantasies.

It is understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application.

Claims

1. Use of a selective mu opioid receptor antagonist in the preparation of a medicament for the treatment and/or prevention of female sexual dysfunction (FSD).

2. Use according to claim 1 , wherein the selective mu opioid receptor antagonist is at least 10-fold selective for mu opioid receptors over kappa opioid receptors in a functional assay.

3. Use according to claim 1 or 2, wherein the selective mu opioid receptor antagonist is at least 50-fold selective for mu opioid receptors over kappa opioid receptors in a functional assay.

4. Use according to any preceding claim, wherein the selective mu opioid receptor antagonist is 10-fold selective for mu opioid receptor over delta opioid receptors in a functional assay.

5. Use according to any preceding claim, wherein the selective mu opioid receptor antagonist is at least 50-fold selective for mu opioid receptors over delta opioid receptors in a functional assay.

6. Use according to any preceding claim, wherein the selective mu opioid receptor antagonist is at least 50-fold selective for mu opioid receptors over kappa opioid receptors and delta opioid receptors in a functional assay.

7. Use according to any preceding claim, wherein the selective mu opioid receptor antagonist is functionally selective for a mu opioid receptor as compared with a kappa opioid receptor, which selectivity is, when using the same assay, at least 3-times the functional selectivity achieved by naltrexone.

8. Use according claim 7, wherein the selectivity is at least 5-times the functional selectivity achieved by naltrexone.

9. Use according to any preceding claim, wherein the selective mu opioid receptor antagonist is functionally selective for a mu opioid receptor as compared with a delta opioid receptor, which selectivity is, when using the same assay, at least 3-times the functional selectivity achieved by naltrexone.

10. Use according to claim 9, wherein the selectivity is at least 5-times the functional selectivity achieved by naltrexone.

11. Use according to any preceding claim, wherein the female sexual dysfunction is female sexual arousal disorder (FSAD).

12. The use according to any one of claims 1 to 10, wherein the female sexual dysfunction is Female Orgasmic Disorder (FOD) or anorgasmia.

13. The use according to any one of claims 1 to 10, wherein the female sexual dysfunction is hypoactive sexual desire disorder (HSDD).

14. The use according to any preceding claim, wherein the selective mu opioid receptor antagonist compound is administered orally, bucally or sublingually.

15. Use according to any preceding claim, wherein the compound is of the formula (I)

wherein X is H, halogen, -OH, -CN, -Ci-C₄ alkyl substituted with from one to three halogen atoms.or -0(Ci-C₄ alkyl), wherein the C₁-C₄ alkyl of -0(Ci-C₄ alkyl) is optionally substituted with from one to three halogen atoms;

Q is halogen, -OH, -0(C₁-C₄ alkyl), -NH₂, -NH(Ci-C₄ alkyl), -N(Ci-C₄ alkyl)(d-C₄ alkyl), -C(=O)NH₂, -C(=O)NH(Ci-C₄ alkyl), -C(=O)N(d- C₄alkyl)(d-C₄ alkyl), -NHS(=O)₂H, or -NHS(=0)2R¹¹;

or Q may form a 5 or 6 membered cycloalkyl or heterocycloalkyl ring with either carbon atom adjacent to the carbon atom to which it is attached, thereby forming a bicyclic fused ring system with the phenyl to which it is attached, wherein said heterocycloalkyl comprises from one to three hetero moities selected from O, S, -C(=O), and N, and wherein said cycloalkyl or heterocycloalkyl optionally contains one or two double bonds;

R¹ and R² are, with the carbon to which they are attached, connected to form a C₃-C₇ cycloalkyl or a 4-7 membered heterocycloalkyl comprising from one to three hetero moities selected fromO, S, -C(=O), and N; and wherein said cycloalkyl or heterocycloalkyl optionally contains one or two double bonds; and wherein said cycloalkyl or heterocycloalkyl is optionally fused to a Ce-C₁₄ aryl or 5-14 membered heteroaryl group;

wherein said C₃-C₇ cycloalkyl or 4-7 membered heterocycloalkyl formed by R¹ and R² can each optionally be substituted by from one to three R¹² groups, and said optionally fused aryl or heteroaryl can each optionally independently be substituted with from one to six R¹² groups, wherein the R¹² groups are selected from R¹³, R¹⁶, -CrC₄ alkyl containing one or two unsaturated bonds, halogen, -OR¹³, -NO₂₁ -CN, - C₃-C₆cycloalkyl, -NR¹³R¹⁴, -NR¹³C(=O)R¹⁴, -C(=O)NR¹³R¹⁴, - OC(O)R¹³, -C(=O)OR¹³, -C(=O)R¹³, -NR¹³C(=O)OR¹⁴, NR¹³C(=O)NR¹⁴R¹⁵, -NR¹³S(=O)₂R¹⁴, and -S(=O)₂R¹³;

R₃ is C₁-C₄ alkyl, wherein said Ci-C₄ alkyl optionally contains one or two unsaturated bonds;

R4 is -C-1-C4 alkyl which may optionally contain one or two unsaturated bonds, -OH, -CN, -NO₂, -OR¹⁶, -NH₂, -NHR¹⁶, -NR¹⁶R¹⁷, or- NHC(=O)R¹⁶;

R⁵ and R⁸ are each independently H or methyl;

R⁶, R⁷, R⁹ and R¹⁰ are H;

R¹¹ is selected from C₁-C₄ alkyl, -(C₁-C₄ alkylene)-O-(C_rC₄ alkyl), 4-(1- methylimidazole), -(C₁-C₄ alkylene)-NH₂, -(C₁-C₄ alkylene)-NH(C₁-C₄ alkyl), -(C₁-C₄ alkylene)-N(C_rC₄ alkyl)(d-C₄ alky⁾);

each R¹³, R¹⁴, and R¹⁵ is independently selected from H, R¹⁶, C₁-C₄ alkyl, halogen, -OH, -SH, -NH₂, -NH(C₁-C₄ alkyl), -N(C₁-C₄ alkyl)(d-C₄ alkyl), -0(C₁-C₄ alkyl), -S(C₁-C₄ alkyl), -CN, -NO₂, -C(^O)(C₁-C₄ alkyl), - C(=O)OH, -C(O)O(C₁-C₄ alkyl), -NHC(=O)(CrC₄ alkyl), -C(=O)NH₂, and -C(=O)N(C_rC₄ alkyl)(C_rC₄ alkyl), or R¹³ and R¹⁴ wherein - NR¹³R¹⁴, may optionally be connected to form a 4 to 6 membered heterocycloalkyl or heteroaryl group, which heterorayl group optionally comprises from 1 to 3 further hetero moieties selected fromN, S₁ O and -C(=O);

each R^1δ and R¹⁷ is independently selected from C₆-Ci₄ aryl and 5-14 membered heteroaryl, wherein said heteroaryl comprises from one to three hetero moities selected from O, S, -C (=0), and N, and wherein said aryl and heteroaryl are optionally substituted with from one to three substituents selected from CrC₄ alkyl optionally containing one or two unsaturated bonds, halogen, -OH, -SH, -NH₂, -NH(CrC₄ alkyl), - N(CrC₄ alkyl)(CrC₄ alkyl),-O(C_rC₄alkyl), -S(C_rC₄alkyl), -CN, -NO₂, - C(=O)(CrC₄alkyl), -C(=O)OH, -C(=O)O(C_rC₄ alkyl), -NHC(=O)(CrC₄ alkyl), -C(=O)NH₂, and -C(=O)N(C_rC₄ alkyl)(CrC₄ alkyl);

and n is an integer selected from zero, 1 , 2, 3, 4, and 5;

or a pharmaceutically acceptable salt thereof.

16. Use according to claim 15, wherein the compound is selected from:

Exo-N-(3-{6-ethyl-3-[3-(1-hydroxy-cyclohexyl)-propyl]-3-a2a- bicyclo[3.1.0]hex-6-yl}-phenyl)-methanesulfonamide citrate;

£xo-N-(3-{6-ethyl-3-[3-(1-hydroxy-cyclohexyl)-propyl]-3-aza- bicyclo[3.1.0]hex-6-yl}-5~fluoro-phenyl)-methanesulfonamide besylate;

Exo-3-{6-ethyl-3-[3-(1-hydroxy-cyclohexyl)-propyl]-3-aza- bicyclo[3.1.0]hex-6-yl}-5~fluoro-benzamide; Exo~3- {6-ethyl-3- [3- (i-hydroxy-cyclohexyQ-propylJ-S-aza-bicyclo [3.

1.0]hex-6-yl}-5~ fluoro-benzamide tosylate;

Exo-N-{3-[6-ethyl-3-(2-hydroxy-indan-2-ylmethy])-3-aza- bicyclo[3.1.Q]hex-6-yl]-phenyl}-methanesulfonamide ;

Exo-2-methoxy-ethanesulfonic acid {3-[6-ethyl-3-(2-hydroxy-indan-2- ylmethyl)-3-aza-bicyclo[3.1.0]hex-6-yl]-phenyl}-amide;

Exo-3-[6-ethyl-3-(2-hydroxy-indan-2-ylmethyl)-3-aza-bicyclo[3.1.0]hex-^°

6-yl]- benzamide;

Exo-3-[6-ethyl-3-(2-hydroxy-indan-2-ylmethyl)-3-aza-bicyclo[3.1.0]hex-

6-yl]-benzamide citrate;

Exo-3-{6-ethyl-3-[3-( 1 -hyd roxy-cycloh exyl )-propyl]-3-aza- bicyclo[3.1.0]hex-6-yl}-phenol;

Exo-3-{6-ethyl-3-[3-(1-hydroxy-cyclohexyl)-propyl]-3-aza- bicyclo[3.1.0]hex-6-yl}- phenol citrate;

Exo-2-[6-ethyl-6-(3-hydroxy-phenyl)-3-aza-bicyclo[3.1.0]hex-3- ylmethyl]-indan-2-ol;

(+/-)-Exo-2-Methoxy-ethanesulfonic acid {3-[6-ethyl-3-(2-hydroxy-

1 ,2,3,4- tetrahydro-naphthalen^-ylmethyO-S-aza-bicyclofS.1.0]hex-6- yl]-phenyl}-amide;

Exo-3-[3-(2-Hydroxy-indan-2-ylmethyl)-6-propyl-3-aza- bicyclo[3.1.0]hex-6-yl]- benzamide;

Exo-3-{3-[3-(1-Hydroxy-cyclohexyl)-propyl]-6-propyl-3-aza- bicyclo[3.1.0]hex-6-yl}- benzamide; Exo-N-(3-{3-[3-(1-Cyano-cyclohexyl)-propyl]-6-ethyl-3-aza- bicyclo[3.1.0]hex-6-yl}- phenyl)-methanesulfonamide;

Exo-2-Methoxy-ethanesulfonic acid {3-[3-(2-hydroxy-indan-2-ylmethyl)-

6-propyl-3-aza-bicyclo[3.1.0]hex-6-yl]-phenyl}-amide;

Exo-N-{3-[3-(2-Hydroxy-indan-2-yImethyl)-6-isopropyl-3-aza- bicyclo[3.1.0]hex-6-yl]-phenyl}-methanesulfonamide;

Exo-2-Methoxy-ethanesulfonic acid (3-{3-[3-(1 -hydroxy-cyclohexyl)- propyI]-6- isopropyl-3-aza-bicyclo[3.1.0]hex-6-yl}-phenyl)-amide;

Exo-N-{3-[6-Ethyl-3-(c/s-1-hydroxy-3-phenyl-cyclobutylmethyl)-3-aza- bicyclo [3.1.0]hex-6-yl]-phenyl}-methanesulfonamidθ;

Exo-3-[6-Ethyl-3-(c/s-1 -hydroxy-3-phenyl-cycIobutylmethyl)-3-aza- bicyclo [3.1.0]hex-6-yl]-benzamide;

Exo-Ethanesulfonic acid {3-[6-ethyI-3-(2-hyroxy-indan-2-ylmethyl)-3- aza- bicyclo[3.1.0]hex-6-yl]-phenyI}-amide; and

Exo-Ethanesulfonic acid(3-{6-ethyl-3-[3-(1-hydroxy-cyclohexyl)-propyl]-

3-aza-bicyclo[3.1.0] hex-6-yl}-phenyl)-amide; and, of the above compounds that are not salt forms, pharmaceutically acceptable salts thereof.

17. Use according to claim 16, wherein the compound is Exo-N-{3-[6-ethyl- 3-(2-hydroxy-indan-2-ylmethyl)-3-aza-bicyclo[3.1.0]hex-6-yl]-phenyl} methanesulfonamide or a pharmaceutically acceptable salt thereof.

18. Use according to claim 17, wherein the compound is Exo-N-{3-[6-ethyl- 3-(2-hydroxy-indan-2-ylmethyl)-3-aza-bicycIo[3.1.0]hex-6-yl]-phenyl} methanesulfonamide mesylate.

19. Use of a selective mu opioid receptor antagonist, together with an auxiliary agent selected from one or more of:

ii) compounds which inhibit angiotensin-converting enzyme; iii) substrates for NO-synthase;

iv) cholesterol lowering agents;

v) estrogen receptor modulators and/or estrogen agonists and/or estrogen antagonists;

vi) phosphodiesterase (PDE) inhibitors;

viii) serotonin receptor agonists, antagonists or modulators;

ix) testosterone replacement agents or a testosterone implants;

x) selective androgen receptor modulators;

xiv) agonists or modulators for oxytocin/vasopressin receptors; xv) melanocortin receptor agonists or modulators;

xvi) mono amine transport inhibitors;

xvii) dopamine agonists (in particular selective D2, selective D3, selective D4 and selective 02-like agents);

xviii) α-adrenergic receptor antagonists (also known as cc-adrenoceptor blockers, α-receptor blockers or α-blockers)

xix) anti-diabetic agents; and

xx) NPY receptor modulators (agonist and/or antagonist)

20. A pharmaceutical composition comprising a selective mu opioid receptor antagonist and one or more auxiliary agents selected from:

ii) compounds which inhibit angiotensin-converting enzyme;

iii) substrates for NO-synthase;

iv) cholesterol lowering agents;

vi) phosphodiesterase (PDE) inhibitors; vii) vasoactive intestinal protein (VIP), VIP mimetic, VIP analogue, a VIP receptor agonist or a VIP fragment, or an adrenoceptor antagonist with VIP combination;

viii) serotonin receptor agonists, antagonists or modulators;

ix) testosterone replacement agents or a testosterone implants;

x) selective androgen receptor modulators;

xiv) agonists or modulators for oxytocin/vasopressin receptors;

xv) melanocortin receptor agonists or modulators;

xvi) mono amine transport inhibitors;

xix) anti-diabetic agents; and

xx) NPY receptor modulators (agonist and/or antagonist).

21. A selective mu opioid receptor antagonist for use in the treatment and/or prevention of female sexual dysfunction (FSD).

22. A method for the treatment and/or prevention of female sexual dysfunction (FSD) comprising administering to a subject in need thereof a therapeutic amount of a selective mu opioid receptor antagonist.