Tachykinin receptors are the targets of a family of structurally related peptides which include substance P (SP), neurokinin A (NKA) and neurokinin B (NKB), named collectively “tachykinins”. Tachykinins are synthesized in the central nervous system (CNS) and peripheral tissues, where they exert a variety of biological activities. Three tachykinin receptors are known which are named neurokinin-1 (NK-1), neurokinin-2 (NK-2) and neurokinin-3 (NK-3) receptors. Tachykinin receptors belong to the rhodopsin-like seven membrane G-protein coupled receptors. SP has the highest affinity and is believed to be the endogenous ligand of NK-1, NKA for NK-2 receptor and NKB for NK-3 receptor, although cross-reactivity amongst these ligands does exist. The NK-1, NK-2 and NK-3 receptors have been identified in different species. NK-1 and NK-2 receptors are expressed in a wide variety of peripheral tissues and NK-1 receptors are also expressed in the CNS; whereas NK-3 receptors are primarily expressed in the CNS.
The neurokinin receptors mediate a variety of tachykinin-stimulated biological effects that include transmission of excitatory neuronal signals in the CNS and periphery (e.g. pain), modulation of smooth muscle contractile activity, modulation of immune and inflammatory responses, induction of hypotensive effects via dilatation of the peripheral vasculature and stimulation of endocrine and exocrine gland secretions.
In the CNS, the NK-3 receptor is expressed in regions including the medial prefrontal cortex, the hippocampus, the thalamus and the amygdala. Moreover, NK-3 receptors are expressed on dopaminergic neurons. Activation of NK-3 receptors has been shown to modulate dopamine, acetylcholine and serotonin release suggesting a therapeutic utility for NK-3 receptor modulators for the treatment of a variety of disorders including psychotic disorders, anxiety, depression, schizophrenia as well as obesity, pain or inflammation (Exp. Opinion Ther. Patents (2000), 10(6), 939-960; Current Opinion in Investigational Drugs, 2001, 2(7), 950-956 and Current Pharmaceutical Design, 2010, 16, 344-357).
Schizophrenia is classified into subgroups. The paranoid type is characterized by delusions and hallucinations and absence of thought disorder, disorganized behavior, and affective flattening. In the disorganized type, which is also named ‘hebephrenic schizophrenia’ in the International Classification of Diseases (ICD), thought disorder and flat affect are present together. In the catatonic type, prominent psychomotor disturbances are evident, and symptoms may include catatonic stupor and waxy flexibility. In the undifferentiated type, psychotic symptoms are present but the criteria for paranoid, disorganized, or catatonic types have not been met. The symptoms of schizophrenia normally manifest themselves in three broad categories, i.e. positive, negative and cognitive symptoms. Positive symptoms are those, which represent an “excess” of normal experiences, such as hallucinations and delusions. Negative symptoms are those where the patient suffers from a lack of normal experiences, such as anhedonia and lack of social interaction. The cognitive symptoms relate to cognitive impairment in schizophrenics, such as a lack of sustained attention and deficits in decision making. The current antipsychotic drugs (APDs) are fairly successful in treating the positive symptoms but fare less well for the negative and cognitive symptoms. Contrary to that, NK3 antagonists have been shown clinically to improve on both positive and negative symptoms in schizophrenics (Meltzer et al, Am. J. Psychiatry, 161, 975-984, 2004) and ameliorate cognitive behavior of schizophrenics (Curr. Opion. Invest. Drug, 6, 717-721, 2005).
In rat, morphological studies provide evidence for putative interactions between NKB neurons and the hypothalamic reproductive axis (Krajewski et al, J. Comp. Neurol., 489(3), 372-386, 2005). In arcuate nucleus neurons, NKB expression co-localizes with estrogen receptor α and dynorphin, implicated in progesterone feedback to Gonadotropin Releasing Hormone (GnRH) secretion (Burke et al., J. Comp. Neurol., 498(5), 712-726, 2006; Goodman et al., Endocrinology, 145, 2959-2967, 2004). Moreover, NK-3 receptor is highly expressed in the hypothalamic arcuate nucleus in neurons which are involved in the regulation of GnRH release.
WO 00/43008 discloses a method of suppressing gonadotropin and/or androgen production with specific NK-3 receptor antagonists. More particularly, the WO 00/43008 application relates to lowering luteinizing hormone (LH) blood level by administering an NK-3 receptor antagonist. Concurrently or alternatively with gonadotropin suppression, WO 00/43008 also relates to suppression of androgen production with NK-3 receptor antagonists. Recently it has been postulated that NKB acts autosynaptically on kisspeptin neurons in the arcuate nucleus to synchronize and shape the pulsatile secretion of kisspeptin and drive the release of GnRH from fibers in the median eminence (Navarro et al., J. of Neuroscience, 23, 2009-pp 11859-11866). All these observations suggest a therapeutic utility for NK-3 receptor modulators for sex hormone-dependent diseases.
Non-peptide ligands have been developed for each of the tachykinin receptors. Some of them have been described as dual modulators able to modulate both NK-2 and NK-3 receptors (WO 06/120478). However, known non-peptide NK-3 receptor antagonists suffer from a number of drawbacks, notably poor safety profile and limited CNS penetrability that may limit the success of these compounds in clinical development.
On this basis, new potent and selective antagonists of NK-3 receptor may be of therapeutic value for the preparation of drugs useful in the treatment and/or prevention of CNS and peripheral diseases or disorders in which NKB and the NK-3 receptors are involved.
Antagonists to Neurokinin-3 Receptor (NK-3)
The invention thus encompasses compounds of general Formula I, their pharmaceutically acceptable salts and solvates as well as methods of use of such compounds or compositions comprising such compounds as antagonists to the NK-3 receptor. Compounds of Formula I are N-acyl-5,6,7,(8-substituted)-tetrahydro-[1,2,4]triazolo[4,3-a]pyrazines. The compounds of the invention are generally disclosed in international patent application PCT/EP2011/055218 but none is specifically exemplified therein.
In a general aspect, the invention provides compounds of general Formula I:
and pharmaceutically acceptable salts and solvates thereof, whereinAr1 is unsubstituted thiophen-2-yl, unsubstituted phenyl, or 4-fluorophenyl;R1 is H or methyl;Ar2 is of general Formula (i), (ii) or (iii):
                wherein        R2 is linear or branched C1-C4 alkyl, C1-C2 haloalkyl, linear or branched C2-C3 alkenyl, C3-C4 cycloalkyl or di(C1-C2 alkyl)amino;        X1 is N or C—R6 wherein R6 is H, fluoro or C1-C2 alkyl;        X2 is O or S;        X3 is N, or X3 is CH under the condition that X1 is N and X2 is N—R7 wherein R7 is linear or branched C1-C3 alkyl or cyclopropyl;        R3 is linear or branched C1-C4 alkyl or C3-C4 cycloalkyl;        X4 is N or C—R8 wherein R8 is H or C1-C2 alkyl;        X5 is O or S;        X6 is N, or X6 is CH under the condition that X4 is N and X5 is N—R9 wherein R9 is linear or branched C1-C3 alkyl or cyclopropyl;        R4 is halo, cyano, methyl, or hydroxyl;        R5 is H or halo;with the condition that when Ar2 is of Formula (iii), then R1 is methyl; andthe compound of Formula I is not            (3-(2-isobutylthiazol-4-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7 (8H)-yl)(4-(thiophen-2-yl)phenyl)methanone;    [1,1′-biphenyl]-4-yl(8-methyl-3-(6-methylpyridin-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone;    (8-methyl-3-(6-methylpyridin-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)(4-(thiophen-2-yl)phenyl)methanone.
In another aspect, the present invention provides a pharmaceutical composition comprising at least one compound according to the invention or a pharmaceutically acceptable salts or solvate thereof.
The invention also relates to the use of the above compounds or their pharmaceutically acceptable salts and solvates as modulators of NK-3 receptors, preferably as antagonists of NK-3 receptors.
The invention further provides methods of treatment and/or prevention of depression, anxiety, pyschosis, schizophrenia, psychotic disorders, bipolar disorders, cognitive disorders, Parkinson's disease, Alzheimer's disease, attention deficit hyperactivity disorder (ADHD), pain, convulsion, obesity, inflammatory diseases including irritable bowel syndrome and inflammatory bowel disorders, emesis, pre-eclampsia, airway related diseases including chronic obstructive pulmonary disease, asthma, airway hyperresponsiveness, bronchoconstriction and cough, reproduction disorders, contraception and sex hormone-dependent diseases including but not limited to benign prostatic hyperplasia (BPH), prostatic hyperplasia, metastatic prostatic carninoma, testicular cancer, breast cancer, ovarian cancer, androgen dependent acne, male pattern baldness, endometriosis, abnormal puberty, uterine fibrosis, uterine fibroid tumor, hormone-dependent cancers, hyperandrogenism, hirsutism, virilization, polycystic ovary syndrome (PCOS), premenstrual dysphoric disease (PMDD), HAIR-AN syndrome (hyperandrogenism, insulin resistance and acanthosis nigricans), ovarian hyperthecosis (HAIR-AN with hyperplasia of luteinized theca cells in ovarian stroma), other manifestations of high intraovarian androgen concentrations (e.g. follicular maturation arrest, atresia, anovulation, dysmenorrhea, dysfunctional uterine bleeding, infertility), androgen-producing tumor (virilizing ovarian or adrenal tumor), menorrhagia and adenomyosis comprising the administration of a therapeutically effective amount of a compound or pharmaceutically acceptable salts or solvate of Formula I, to a patient in need thereof. Preferably the patient is a warm-blooded animal, more preferably a human.
The invention further provides methods of treatment for gynecological disorders and infertility. In particular, the invention provides methods to suppress the LH-surge in assisted conception comprising the administration of a therapeutically effective amount of a compound or pharmaceutically acceptable salts or solvate of Formula I, to a patient in need thereof. Preferably the patient is a warm-blooded animal, more preferably a woman.
The invention further provides methods to affect androgen production to cause male castration and to inhibit the sex drive in male sexual offenders comprising the administration of a therapeutically effective amount of a compound or pharmaceutically acceptable salts or solvate of Formula I, to a patient in need thereof. Preferably the patient is a warm-blooded animal, more preferably a man.
The invention also provides the use of a compound of Formula I or a pharmaceutically acceptable salts or solvate thereof as a medicament. Preferably, the medicament is used for the treatment and/or prevention of depression, anxiety, pyschosis, schizophrenia, psychotic disorders, bipolar disorders, cognitive disorders, Parkinson's disease, Alzheimer's disease, attention deficit hyperactivity disorder (ADHD), pain, convulsion, obesity, inflammatory diseases including irritable bowel syndrome and inflammatory bowel disorders, emesis, pre-eclampsia, airway related diseases including chronic obstructive pulmonary disease, asthma, airway hyperresponsiveness, bronchoconstriction and cough, reproduction disorders, contraception and sex hormone-dependent diseases including but not limited to benign prostatic hyperplasia (BPH), prostatic hyperplasia, metastatic prostatic carninoma, testicular cancer, breast cancer, ovarian cancer, androgen dependent acne, male pattern baldness, endometriosis, abnormal puberty, uterine fibrosis, uterine fibroid tumor, hormone-dependent cancers, hyperandrogenism, hirsutism, virilization, polycystic ovary syndrome (PCOS), premenstrual dysphoric disease (PMDD), HAIR-AN syndrome (hyperandrogenism, insulin resistance and acanthosis nigricans), ovarian hyperthecosis (HAIR-AN with hyperplasia of luteinized theca cells in ovarian stroma), other manifestations of high intraovarian androgen concentrations (e.g. follicular maturation arrest, atresia, anovulation, dysmenorrhea, dysfunctional uterine bleeding, infertility), androgen-producing tumor (virilizing ovarian or adrenal tumor), menorrhagia and adenomyosis. The medicament may also be used for the treatment of gynecologic disorders, infertility and to affect androgen production to cause male castration.