Discovery of MK-1468: A Potent, Kinome-Selective, Brain-Penetrant Amidoisoquinoline LRRK2 Inhibitor for the Potential Treatment of Parkinson's Disease.

Genetic mutation of the leucine-rich repeat kinase 2 (LRRK2) protein has been associated with Parkinson's disease (PD), a disabling and progressive neurodegenerative disorder that is devoid of efficacious disease-modifying therapies. Herein, we describe the invention of an amidoisoquinoline (IQ)-derived LRRK2 inhibitor lead chemical series. Knowledge-, structure-, and property-based drug design in concert with rigorous application of in silico calculations and presynthesis predictions enabled the prioritization of molecules with favorable CNS "drug-like" physicochemical properties. This resulted in the discovery of compound 8, which was profiled extensively before human ether-a-go-go (hERG) ion channel inhibition halted its progression. Strategic reduction of lipophilicity and basicity resulted in attenuation of hERG ion channel inhibition while maintaining a favorable CNS efflux transporter profile. Further structure- and property-based optimizations resulted in the discovery of preclinical candidate MK-1468. This exquisitely selective LRRK2 inhibitor has a projected human dose of 48 mg BID and a preclinical safety profile that supported advancement toward GLP toxicology studies.

Discovery and Optimization of Potent, Selective, and Brain-Penetrant 1-Heteroaryl-1H-Indazole LRRK2 Kinase Inhibitors for the Treatment of Parkinson's Disease.

Inhibition of leucine-rich repeat kinase 2 (LRRK2) kinase activity represents a genetically supported, chemically tractable, and potentially disease-modifying mechanism to treat Parkinson's disease. Herein, we describe the optimization of a novel series of potent, selective, central nervous system (CNS)-penetrant 1-heteroaryl-1H-indazole type I (ATP competitive) LRRK2 inhibitors. Type I ATP-competitive kinase physicochemical properties were integrated with CNS drug-like properties through a combination of structure-based drug design and parallel medicinal chemistry enabled by sp3-sp2 cross-coupling technologies. This resulted in the discovery of a unique sp3-rich spirocarbonitrile motif that imparted extraordinary potency, pharmacokinetics, and favorable CNS drug-like properties. The lead compound, 25, demonstrated exceptional on-target potency in human peripheral blood mononuclear cells, excellent off-target kinase selectivity, and good brain exposure in rat, culminating in a low projected human dose and a pre-clinical safety profile that warranted advancement toward pre-clinical candidate enabling studies.

Ileocolonic-Targeted JAK Inhibitor: A Safer and More Effective Treatment for Inflammatory Bowel Disease.

Janus kinase (JAK) inhibitors, such as tofacitinib (Xeljanz) and filgotinib (Jyseleca), have been approved for treatment of ulcerative colitis with several other JAK inhibitors in late-stage clinical trials for inflammatory bowel disease (IBD). Despite their impressive efficacy, the risk of adverse effects accompanying the use of JAK inhibitors has brought the entire class under scrutiny, leading to them receiving an FDA black box warning. In this study we investigated whether ileocolonic-targeted delivery of a pan-JAK inhibitor, tofacitinib, can lead to increased tissue exposure and reduced systemic exposure compared to untargeted formulations. The stability of tofacitinib in the presence of rat colonic microbiota was first confirmed. Next, in vivo computed tomography imaging was performed in rats to determine the transit time and disintegration site of ileocolonic-targeted capsules compared to gastric release capsules. Pharmacokinetic studies demonstrated that systemic drug exposure was significantly decreased, and colonic tissue exposure increased at 10 mg/kg tofacitinib dosed in ileocolonic-targeted capsules compared to gastric release capsules and an oral solution. Finally, in a rat model of LPS-induced colonic inflammation, targeted tofacitinib capsules significantly reduced concentrations of proinflammatory interleukin 6 in colonic tissue compared to a vehicle-treated control (p = 0.0408), unlike gastric release tofacitinib capsules and orally administered dexamethasone. Overall, these results support further development of ileocolonic-targeted tofacitinib, and potentially other specific JAK inhibitors in pre-clinical and clinical development, for the treatment of IBD.

Structure-Guided Discovery of Aminoquinazolines as Brain-Penetrant and Selective LRRK2 Inhibitors.

The leucine-rich repeat kinase 2 (LRRK2) protein has been genetically and functionally linked to Parkinson's disease (PD), a disabling and progressive neurodegenerative disorder whose current therapies are limited in scope and efficacy. In this report, we describe a rigorous hit-to-lead optimization campaign supported by structural enablement, which culminated in the discovery of brain-penetrant, candidate-quality molecules as represented by compounds 22 and 24. These compounds exhibit remarkable selectivity against the kinome and offer good oral bioavailability and low projected human doses. Furthermore, they showcase the implementation of stereochemical design elements that serve to enable a potency- and selectivity-enhancing increase in polarity and hydrogen bond donor (HBD) count while maintaining a central nervous system-friendly profile typified by low levels of transporter-mediated efflux and encouraging brain penetration in preclinical models.

Optimization of brain-penetrant picolinamide derived leucine-rich repeat kinase 2 (LRRK2) inhibitors.

The discovery of potent, kinome selective, brain penetrant LRRK2 inhibitors is the focus of extensive research seeking new, disease-modifying treatments for Parkinson's disease (PD). Herein, we describe the discovery and evolution of a picolinamide-derived lead series. Our initial optimization efforts aimed at improving the potency and CLK2 off-target selectivity of compound 1 by modifying the heteroaryl C-H hinge and linker regions. This resulted in compound 12 which advanced deep into our research operating plan (ROP) before heteroaryl aniline metabolite 14 was characterized as Ames mutagenic, halting its progression. Strategic modifications to our ROP were made to enable early de-risking of putative aniline metabolites or hydrolysis products for mutagenicity in Ames. This led to the discovery of 3,5-diaminopyridine 15 and 4,6-diaminopyrimidine 16 as low risk for mutagenicity (defined by a 3-strain Ames negative result). Analysis of key matched molecular pairs 17 and 18 led to the prioritization of the 3,5-diaminopyridine sub-series for further optimization due to enhanced rodent brain penetration. These efforts culminated in the discovery of ethyl trifluoromethyl pyrazole 23 with excellent LRRK2 potency and expanded selectivity versus off-target CLK2.

Characterization of the Onset, Progression, and Reversibility of Morphological Changes in Mouse Lung after Pharmacological Inhibition of Leucine-Rich Kinase 2 Kinase Activity.

Gain-of-function mutations in leucine-rich kinase 2 (LRRK2) are associated with increased incidence of Parkinson disease (PD); thus, pharmacological inhibition of LRRK2 kinase activity is postulated as a disease-modifying treatment of PD. Histomorphological changes in lungs of nonhuman primates (NHPs) treated with small-molecule LRRK2 kinase inhibitors have brought the safety of this treatment approach into question. Although it remains unclear how LRRK2 kinase inhibition affects the lung, continued studies in NHPs prove to be both cost- and resource-prohibitive. To develop a tractable alternative animal model platform, we dosed male mice in-diet with the potent, highly selective LRRK2 kinase inhibitor MLi-2 and induced histomorphological changes in lung within 1 week. Oral bolus dosing of MLi-2 at a frequency modeled to provide steady-state exposure equivalent to that achieved with in-diet dosing induced type II pneumocyte vacuolation, suggesting pulmonary changes require sustained LRRK2 kinase inhibition. Treating mice with MLi-2 in-diet for up to 6 months resulted in type II pneumocyte vacuolation that progressed only modestly over time and was fully reversible after withdrawal of MLi-2. Immunohistochemical analysis of lung revealed a significant increase in prosurfactant protein C staining within type II pneumocytes. In the present study, we demonstrated the kinetics for onset, progression, and rapid reversibility of chronic LRRK2 kinase inhibitor effects on lung histomorphology in rodents and provide further evidence for the derisking of safety and tolerability concerns for chronic LRRK2 kinase inhibition in PD. SIGNIFICANCE STATEMENT: We have defined a mouse model by which the on-target lung effects of leucine-rich kinase 2 (LRRK2) kinase inhibition can be monitored, whereas previous in vivo testing relied solely on nonhuman primates. Data serve to derisk long-term treatment with LRRK2 kinase inhibitors, as all lung changes were mild and readily reversible.

Discovery of N-(Indazol-3-yl)piperidine-4-carboxylic Acids as RORγt Allosteric Inhibitors for Autoimmune Diseases.

The clinical success of anti-IL-17 monoclonal antibodies (i.e., Cosentyx and Taltz) has validated Th17 pathway modulation for the treatment of autoimmune diseases. The nuclear hormone receptor RORγt is a master regulator of Th17 cells and affects the production of a host of cytokines, including IL-17A, IL-17F, IL-22, IL-26, and GM-CSF. Substantial interest has been spurred across both academia and industry to seek small molecules suitable for RORγt inhibition. A variety of RORγt inhibitors have been reported in the past few years, the majority of which are orthosteric binders. Here we disclose the discovery and optimization of a class of inhibitors, which bind differently to an allosteric binding pocket. Starting from a weakly active hit 1, a tool compound 14 was quickly identified that demonstrated superior potency, selectivity, and off-target profile. Further optimization focused on improving metabolic stability. Replacing the benzoic acid moiety with piperidinyl carboxylate, modifying the 4-aza-indazole core in 14 to 4-F-indazole, and incorporating a key hydroxyl group led to the discovery of 25, which possesses exquisite potency and selectivity, as well as an improved pharmacokinetic profile suitable for oral dosing.

Discovery of TD-0212, an Orally Active Dual Pharmacology AT1 Antagonist and Neprilysin Inhibitor (ARNI).

Dual inhibition of angiotensin-converting enzyme (ACE) and neprilysin (NEP) by drugs such as omapatrilat produces superior antihypertensive efficacy relative to ACE inhibitors but is associated with a higher risk of life-threatening angioedema due to bradykinin elevations. We hypothesized that dual AT1 (angiotensin II type 1 receptor) blockade and NEP inhibition with a single molecule would produce similar antihypertensive efficacy to omapatrilat without the risk of angioedema since ACE (the rate limiting enzyme in bradykinin metabolism) would remain uninhibited. Merging the structures of losartan (an AT1 antagonist) and thiorphan (a NEP inhibitor) led to the discovery of a novel series of orally active, dual AT1 antagonist/NEP inhibitors (ARNIs) exemplified by compound 35 (TD-0212). In models of renin-dependent and -independent hypertension, 35 produced blood pressure reductions similar to omapatrilat and combinations of AT1 receptor antagonists and NEP inhibitors. Upper airway angioedema risk was assessed in a rat tracheal plasma extravasation (TPE) model. Unlike omapatrilat, 35 did not increase TPE at antihypertensive doses. Compound 35 therefore provides the enhanced activity of dual AT1/NEP inhibition with a potentially lower risk of angioedema relative to dual ACE/NEP inhibition.

Inhibition of RORγT Skews TCRα Gene Rearrangement and Limits T Cell Repertoire Diversity.

Recent studies have elucidated the molecular mechanism of RORγT transcriptional regulation of Th17 differentiation and function. RORγT was initially identified as a transcription factor required for thymopoiesis by maintaining survival of CD4+CD8+ (DP) thymocytes. While RORγ antagonists are currently being developed to treat autoimmunity, it remains unclear how RORγT inhibition may impact thymocyte development. In this study, we show that in addition to regulating DP thymocytes survival, RORγT also controls genes that regulate thymocyte migration, proliferation, and T cell receptor (TCR)α selection. Strikingly, pharmacological inhibition of RORγ skews TCRα gene rearrangement, limits T cell repertoire diversity, and inhibits development of autoimmune encephalomyelitis. Thus, targeting RORγT not only inhibits Th17 cell development and function but also fundamentally alters thymic-emigrant recognition of self and foreign antigens. The analysis of RORγ inhibitors has allowed us to gain a broader perspective of the diverse function of RORγT and its impact on T cell biology.

Concomitant angiotensin AT1 receptor antagonism and neprilysin inhibition produces omapatrilat-like antihypertensive effects without promoting tracheal plasma extravasation in the rat.

Dual inhibition of angiotensin-converting enzyme (ACE) and neprilysin (NEP) by drugs such as omapatrilat produces superior antihypertensive efficacy but cause high incidence of angioedema. We examined whether dual inhibition of angiotensin AT1 receptor (ARB) and NEP (ARB-NEPI, valsartan-candoxatril) provides similar efficacy to omapatrilat without the risk of angioedema. Activity of test compounds at the targets was assayed using fluorescence-based enzyme assays (ACE, NEP, aminopeptidase P) or competition binding assays (AT1). Target engagement in vivo (ACE, AT1, and NEP) was quantified by measuring inhibition of angiotensin-pressor responses and potentiation of atrial natriuretic peptide-induced urinary cyclic guanosine monophosphate (cGMP) output in rats. Tracheal plasma extravasation (TPE) was used as a surrogate to assess propensity of compounds to promote upper airway angioedema. Antihypertensive efficacy in renin-dependent and -independent states was measured in spontaneously hypertensive rats and deoxycorticosterone acetate salt hypertensive rats, respectively. Administration of omapatrilat and coadministration of valsartan and candoxatril blocked angiotensin induced vasopressor responses and potentiated atrial natriuretic peptide-induced increase in urinary cGMP output. In spontaneously hypertensive rats, valsartan, omapatrilat, and valsartan-candoxatril combination all produced reduction in blood pressure to a similar extent, whereas candoxatril was ineffective. In deoxycorticosterone acetate rats, omapatrilat, candoxatril, and valsartan-candoxatril combination but not valsartan produced reduction in blood pressure. Antihypertensive doses of omapatrilat produced robust increases in TPE; by contrast, valsartan, candoxatril, or their combination did not increase TPE. Pretreatment with icatibant, a bradykinin B2 antagonist, abolished omapatrilat-induced TPE but not its antihypertensive effects. On the background of NEP inhibition, suppression of the renin-angiotensin system through ARB and ACE inhibition shows a similar antihypertensive efficacy but exerts differential effects on bradykinin metabolism and TPE indicative of reduced risk of angioedema. Thus, dual AT1 receptor blockade and NEP inhibition is potentially an attractive approach to retain the excellent antihypertensive effects of omapatrilat but with a superior safety profile.

RBx 6198: a novel alpha1-adrenoceptor antagonist for the treatment of benign prostatic hyperplasia.

The present study, investigates the effect of RBx 6198, 2-{3-[4-(2-Isopropoxy-phenyl)-piperazin-1-yl]-propyl}-3a, 4, 7, 7a-tetrahydro-isoindole-1, 3,-dione, a novel alpha(1)-adrenoceptor antagonist, in both in vitro and in vivo test systems. RBx 6198 is a potent (nanomolar affinity) alpha(1A)-adrenoceptor antagonist with demonstrable uroselectivity in anaesthesized dog model. In radioligand binding studies using human recombinant receptors, RBx 6198 exhibited high selectivity (approximately 50 fold) for the alpha(1A)-adrenoceptor subtype as compared to alpha(1B)-adrenoceptor subtype. In order to assess tissue selectivity, the antagonistic effect of RBx 6198 on the phenylephrine induced contractile response of isolated rat prostate, spleen and aorta was characterized. RBx 6198 was 8 fold more potent in inhibiting phenylephrine-evoked contractions of isolated tissues compared to tamsulosin. However, the compound was non-selective for alpha(1A) vs. alpha(1D)-adrenoceptor like tamsulosin. In anaesthetized beagle dogs RBx 6198 suppressed the intraurethral pressure response to phenylephrine to a greater extent than the mean arterial pressure response thereby demonstrating uroselectivity consistent with in vitro binding and functional data. RBx 6198 was 6.4 fold more uroselective as compared to tamsulosin after i.v. route dose administration. Taken together all results from preclinical studies, it is suggested that RBx 6198 is a novel alpha(1)-adrenoceptor antagonist that exhibited improved pharmacological profile over tamsulosin in both in vitro and in vivo.

The novel neuropeptide Y Y5 receptor antagonist Lu AA33810 [N-[[trans-4-[(4,5-dihydro[1]benzothiepino[5,4-d]thiazol-2-yl)amino]cyclohexyl]methyl]-methanesulfonamide] exerts anxiolytic- and antidepressant-like effects in rat models of stress sensitivity.

Neuropeptide Y (NPY) regulates physiological processes via receptor subtypes (Y(1), Y(2), Y(4), Y(5), and y(6)). The Y(5) receptor is well known for its role in appetite. Based on expression in the limbic system, we hypothesized that the Y(5) receptor might also modulate stress sensitivity. We identified a novel Y(5) receptor-selective antagonist, Lu AA33810 [N-[[trans-4-[(4,5-dihydro[1]-benzothiepino[5,4-d]thiazol-2-yl)amino]cyclohexyl]methyl]-methanesulfonamide], that bound to cloned rat Y(5) receptors (K(i) = 1.5 nM) and antagonized NPY-evoked cAMP and calcium mobilization in vitro. Lu AA33810 (3-30 mg/kg p.o.) blocked feeding elicited by intracerebroventricular injection of the Y(5) receptor-selective agonist [cPP(1-7),NPY(19-23),Ala(31),Aib(32),Gln(34)]-hPancreatic Polypeptide in Sprague-Dawley rats. In vivo effects of Lu AA33810 were correlated with brain exposure > or = 50 ng/g and ex vivo Y(5) receptor occupancy of 22 to 95%. Lu AA33810 was subsequently evaluated in models of stress sensitivity. In Fischer 344 rats, Lu AA33810 (30 mg/kg p.o.) attenuated increases in plasma ACTH and corticosterone elicited by intracerebroventricular injection of [cPP(1-7),NPY(19-23),Ala(31),Aib(32),Gln(34)]-hPancreatic Polypeptide. In Sprague-Dawley rats subjected to the social interaction test, Lu AA33810 (3-30 mg/kg p.o.) produced anxiolytic-like effects after acute or chronic treatment. In Flinders sensitive line rats, chronic dosing of Lu AA33810 (10 mg/kg/day i.p.) produced anxiolytic-like effects in the social interaction test, plus antidepressant-like effects in the forced swim test. In Wistar rats exposed to chronic mild stress, chronic dosing of Lu AA33810 (3 and 10 mg/kg/day i.p.) produced antidepressant-like activity, i.e., normalization of stress-induced decrease in sucrose consumption. We propose that Y(5) receptors may function as part of an endogenous stress-sensing system to mediate social anxiety and reward or motivational deficits in selected rodent models.

The role of melanin-concentrating hormone-1 receptors in the voiding reflex in rats.

We have used the selective melanin-concentrating hormone-1 (MCH(1)) receptor antagonist SNAP 7941 [((+)-methyl (4S)-3-{[(3-{4-[3-(acetylamino)phenyl]-1-piperidinyl}propyl) amino]carbonyl}-4-(3,4-difluorophenyl)-6-(methoxymethyl)-2-oxo-1,2,3,4-tetrahydro-5-pyrimidinecarboxylate hydrochloride)] to investigate the role of the hypothalamic neuropeptide MCH in the control of voiding in rats. Intravenous administration of SNAP 7941 (3 and 10 mg/kg i.v.) produced dose-related inhibition of rhythmic, distension-induced voiding contractions in anesthetized rats. In conscious rats in which repeated voiding cycles were evoked by continuous slow transvesicular infusion of saline, intragastric SNAP 7941 [0.03-1 mg/kg intragastrically (i.g.)] produced sustained increases in infusion capacity (maximum = 220% basal), comparable with the effects of the 5-hydroxytryptamine(1A) antagonist WAY 100635 (N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinyl-cyclohexanecarboxamide maleate salt), and the muscarinic antagonist, oxybutynin (4-diethylaminobut-2-ynyl 2-cyclohexyl-2-hydroxy-2-phenylacetate hydrochloride). SNAP 7941 produced similar results when administered at a low dose (0.01 nmol) into the lateral ventricle (intracerebroventricular). The opposite effect was produced when MCH (20 nmol) was delivered intracerebroventricularly, resulting in a 34% decrease in apparent bladder capacity with increased urinary frequency. The effect of MCH was blocked by the prior intragastric administration of SNAP 7941 (0.1 mg/kg), but oxybutynin (1 mg/kg) was ineffective. Finally, in conscious spontaneously hypertensive rats, SNAP 7941 (0.1 mg/kg i.g.) produced a 31% reduction in micturition frequency, accompanied by a 36% increase in bladder capacity, with no effect on total volume voided over 6 h. The data indicate that MCH acts via MCH(1) receptors within the CNS to modulate the voiding reflex in rats. The striking effects of the MCH(1) antagonist SNAP 7941 to increase bladder capacity and reduce voiding frequency indicate that MCH(1) antagonists may offer a potential novel approach for treating overactive bladder syndrome.

The effects of stressful stimuli and hypothalamic-pituitary-adrenal axis activation are reversed by the melanin-concentrating hormone 1 receptor antagonist SNAP 94847 in rodents.

Melanin-concentrating hormone (MCH) is an orexigenic and dipsogenic neuropeptide that has been reported to mediate acute behavioral and neuroendocrine stress-related responses via MCH(1) receptor activation in rodents. The purpose of the present investigation was to use the MCH(1) receptor antagonist SNAP 94847 (N-(3-{1-[4-(3,4-difluoro-phenoxy)-benzyl]-piperidin-4-yl}-4-methyl-phenyl)-isobutyramide) to determine the effects of MCH(1) receptor blockade on MCH-evoked adrenocorticotropic hormone (ACTH) release, chronic mild stress-induced anhedonia, stress-induced hyperthermia and forced swim stress-induced immobility. The appropriate dose range for testing SNAP 94847 was determined by measuring MCH-evoked water drinking. The corresponding occupancy of MCH(1) receptors in rat striatum was also measured across a broad dose range. Orally administered (p.o.) SNAP 94847 (1-10 mg/kg) corresponds to 30-60% occupancy at MCH(1) receptors and significantly blocks water drinking induced by the intracerebroventricular (i.c.v.) injection of MCH. MCH (i.c.v.) significantly elevates plasma levels of ACTH in rats, and SNAP 94847 (2.5 mg/kg, p.o.) blocks MCH-evoked ACTH release. Using the chronic mild stress paradigm, we show that repeated daily exposure to environmental stressors for 5 weeks significantly suppresses sucrose intake in rats, and that SNAP 94847 (1 mg/kg, BID) for 1-5 weeks restores baseline sucrose intake. Moreover, a single administration of SNAP 94847 attenuates stress-induced hyperthermia and the behavioral effects of forced swim stress with minimal effective doses of 2.5 and 30 mg/kg (p.o.), respectively. The regulation of ACTH release and reversal of the effects of chronic and acute stress by SNAP 94847 are suggestive of a role for MCH(1) receptor blockade in the treatment of disorders characterized by high allostatic load.

Synthesis and SAR investigations for novel melanin-concentrating hormone 1 receptor (MCH1) antagonists Part 1. The discovery of arylacetamides as viable replacements for the dihydropyrimidinone moiety of an HTS hit.

Melanin-concentrating hormone (MCH) is involved in the regulation of feeding, water balance, energy metabolism, general arousal and attention state, memory, cognitive functions, and psychiatric disorders. Herein, two new chemical series exemplified by N-[5-(1-{3-[2,2-bis-(4-fluoro-phenyl)-acetylamino]-propyl}-piperidin-4-yl)-2,4-difluoro-phenyl]-isobutyramide (SNAP 102739, 5m) and N-[3-(1-{3-[(S)-2-(4-fluoro-phenyl)-propionylamino]-propyl}-piperidin-4-yl)-4-methylphenyl]-isobutyramide ((S)-6b) are reported. These compounds were designed to improve the pharmacokinetic properties of the high-throughput screening lead compound 1 (SNAP 7941). The MCH1 receptor antagonists 5m and (S)-6b show reasonable pharmacokinetic profiles (rat bioavailability = 48 and 81%, respectively). Compounds 5m and (S)-6b demonstrated the inhibition of a centrally administered MCH-evoked drinking effect, and compound 5m exhibited oral in vivo efficacy in the rat social interaction model of anxiety, with a minimum effective dose = 0.3 mg/kg.

Synthesis and SAR investigations for novel melanin-concentrating hormone 1 receptor (MCH1) antagonists part 2: A hybrid strategy combining key fragments of HTS hits.

A novel series of melanin-concentrating hormone (MCH1) receptor antagonists based on combining key fragments from the high-throughput screening (HTS) hits compound 2 (SNAP 7941) and compound 5 (chlorohaloperidol) are described. The resultant analogs, exemplified by compounds 11a-11h, 15a-15h, and 16a-16g, were evaluated in in vitro and in vivo assays for their potential in treatment of mood disorders. From further SAR investigations, N-(3-{1-[4-(3,4-difluorophenoxy)benzyl]-4-piperidinyl}-4-methylphenyl)-2-methylpropanamide (16g, SNAP 94847) was identified to be a high affinity and selective ligand for the MCH1 receptor. Compound 16g also shows good oral bioavailability (59%) and exhibits a brain/plasma ratio of 2.3 in rats. Compound 16g showed in vivo inhibition of a centrally induced MCH-induced drinking effect and exhibited a dose-dependent anxiolytic effect in the rat social interaction model.

Comparative in vivo uroselectivity profiles of anticholinergics, tested in a novel anesthetized rabbit model.

The aim of this study was to describe a new experimental animal model for simultaneous measurement of carbachol-induced increase in intravesical pressure and salivary secretion in rabbits. Further, we also compared the in vivo potency and urinary bladder versus salivary gland selectivity profiles of Oxybutynin, Tolterodine, Solifenacin and Darifenacin. The intravesical pressure and salivary secretion were evoked by intra-arterial injection of carbachol (1.5 microg/kg). The carbachol-induced increase in intravesical pressure and salivation was simultaneously recorded before and after increasing doses of test drugs administered intravenously. The basal mean changes in intravesical pressure and salivation subsequent to carbachol administration were in the range of 6.7-7.5 mm Hg and 0.5-0.7 g respectively. Repeated administration of vehicle did not elicit any appreciable changes in intravesical pressure and salivary secretion to carbachol administration from the basal values till 3 h. All the test drugs exhibited a dose-dependent inhibition of carbachol-induced increase in intravesical pressure and salivary secretion. Darifenacin demonstrated a greater potency compared to other muscarinic receptor antagonists for inhibiting carbachol-induced increase in intravesical pressure. It also exhibited functional selectivity for the urinary bladder versus salivary gland. In contrast, Oxybutynin was functionally more selective in inhibiting carbachol-induced increase in salivary secretion. The observed urinary bladder versus salivary selectivity values were 0.6+/-0.2, 1.1+/-0.2, 1.7+/-0.5, and 2.3+/-0.5 for Oxybutynin, Tolterodine, Solifenacin and Darifenacin respectively. These results suggest that the functional selectivity of muscarinic receptor antagonists between urinary bladder and salivary glands can be readily detected in this model. Thus rabbits may represent a useful animal model for evaluating putative bladder selective muscarinic receptor antagonists for the treatment of overactive bladder.