Synthesis and structure-activity relationships of pyrido[3,2-b]pyrazin-3(4H)-ones and pteridin-7(8H)-ones as corticotropin-releasing factor-1 receptor antagonists.

Pyrido[3,2-b]pyrazin-3(4H)-ones and pteridin-7(8H)-ones were evaluated as corticotropin-releasing factor-1 receptor antagonists. The synthesis, SAR studies and pharmacokinetic evaluation of these analogs are described herein.

Metabolism, excretion, and pharmacokinetics of [14C]INCB018424, a selective Janus tyrosine kinase 1/2 inhibitor, in humans.

The metabolism, excretion, and pharmacokinetics of 3-(4-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl)-3-cyclopentylpropanenitrile (INCB018424), a potent, selective inhibitor of Janus tyrosine kinase1/2 and the first investigational drug of its class in phase III studies for the treatment of myelofibrosis, were investigated in healthy human subjects given a single oral 25-mg dose of [(14)C]INCB018424 as an oral solution. INCB018424 and total radioactivity were absorbed rapidly (mean time to reach the maximal drug concentration <1 h), declining in a monophasic or biphasic fashion (mean t(1/2) of 2.32 and 5.81 h, respectively). Recovery of administered radioactivity was fairly rapid (>70% within 24 h postdose) with 74 and 22% recovered in urine and feces, respectively. Parent compound was the predominant entity in the circulation, representing 58 to 74% of the total radioactivity up to 6 h postdose, indicating that the overall circulating metabolite burden was low (<50% of parent). Two metabolite peaks in plasma (M18 and a peak containing M16/M27, both hydroxylations on the cyclopentyl moiety) were identified as major (30 and 14% of parent based on area under the curve from 0 to 24 h). The exposures of other circulating INCB018424-related peaks were <10% of parent, consisting of mono- and dihydroxylated metabolites. The profiles in urine and feces consisted of hydroxyl and oxo metabolites and subsequent glucuronide conjugates with parent drug accounting for <1% of the excreted dose, strongly suggesting that after an oral dose, INCB018424 was >95% absorbed. In healthy subjects administered daily oral doses of unlabeled INCB018424, there were minimal differences in parent and metabolite concentrations between day 1 and day 10, indicating a lack of accumulation of parent or metabolites between single and multiple dosing.

In vitro intrinsic clearance-based optimization of N3-phenylpyrazinones as corticotropin-releasing factor-1 (CRF1) receptor antagonists.

A series of pyrazinone-based heterocycles was identified as potent and orally active corticotropin-releasing factor-1 (CRF(1)) receptor antagonists. Selected compounds proved efficacious in an anxiety model in rats; however, pharmacokinetic properties were not optimal. In this article, we describe an in vitro intrinsic clearance-based approach to the optimization of pyrazinone-based CRF(1) receptor antagonists wherein sites of metabolism were identified by incubation with human liver microsomes. It was found that the rate of metabolism could be decreased by incorporation of appropriate substituents at the primary sites of metabolism. This led to the discovery of compound 12x, a highly potent (IC(50) = 1.0 nM) and selective CRF(1) receptor antagonist with good oral bioavailability (F = 52%) in rats and efficacy in the defensive withdrawal anxiety test in rats.

Synthesis, structure-activity relationships, and in vivo evaluation of N3-phenylpyrazinones as novel corticotropin-releasing factor-1 (CRF1) receptor antagonists.

Evidence suggests that corticotropin-releasing factor-1 (CRF(1)) receptor antagonists may offer therapeutic potential for the treatment of diseases associated with elevated levels of CRF such as anxiety and depression. A pyrazinone-based chemotype of CRF(1) receptor antagonists was discovered. Structure-activity relationship studies led to the identification of numerous potent analogues including 12p, a highly potent and selective CRF(1) receptor antagonist with an IC(50) value of 0.26 nM. The pharmacokinetic properties of 12p were assessed in rats and Cynomolgus monkeys. Compound 12p was efficacious in the defensive withdrawal test (an animal model of anxiety) in rats. The synthesis, structure-activity relationships and in vivo properties of compounds within the pyrazinone chemotype are described.

Synthesis and evaluation of 2-anilino-3-phenylsulfonyl-6-methylpyridines as corticotropin-releasing factor1 receptor ligands.

A novel series of 2-anilino-3-phenylsulfonyl-6-methylpyridines was synthesized and evaluated as corticotropin-releasing factor receptor ligands. Structure-activity relationship studies focused primarily on optimization of the 3-phenylsulfonyl group. Compounds within this series were identified which showed potent binding affinity for the CRF1 receptor. Selected compounds were examined in a rat pharmacokinetic study and were found to have oral bioavailabilities ranging from 16 to 35%.

Imidazo[4,5-b]pyridines as corticotropin releasing factor receptor ligands.

A series of high affinity CRF receptor ligands with an imidazo[4,5-b]pyridine core is described. Individual analogues were synthesized and tested in a rat CRF receptor binding assay. The best compounds were further tested in the dog N-in-1 pharmacokinetic model to assess plasma levels at 1mg/kg (po) and in the rat situational anxiety model to assess anxiolytic efficacy at 3mg/kg (po). The structure-activity relationships for good receptor binding affinity are described herein.

Imidazo[4,5-c]pyridines as corticotropin releasing factor receptor ligands.

A series of high affinity CRF receptor ligands with an imidazo[4,5-c]pyridine core is described. Individual analogues were synthesized and tested in vitro in rat brain receptors to determine binding affinity. The best compound was further tested in the dog N-in-1 pharmacokinetic model to assess oral bioavailability at 1 mg/kg po.

CRF ligands via Suzuki and Negishi couplings of 3-pyridyl boronic acids or halides with 2-benzyloxy-4-chloro-3-nitropyridine.

A series of imidazo[4,5-b]pyridines with a 7-(3-pyridyl) substituent is described as high affinity CRF receptor ligands. Individual analogues were synthesized from key intermediates obtained via palladium-catalyzed coupling of 3-pyridyl zinc or boronic acid organometallic intermediates with 2-benzyloxy-4-chloro-3-nitropyridine 12.