Calcitonin gene-related peptide (CGRP) receptor antagonists: Heterocyclic modification of a novel azepinone lead.

In our efforts to identify orally bioavailable CGRP receptor antagonists, we previously discovered a novel series of orally available azepinone derivatives that unfortunately also exhibited the unwanted property of potent time-dependent human CYP3A4 inhibition. Through heterocyclic replacement of the indazole ring, we discovered a series of heterocycle derivatives as high-affinity CGRP receptor antagonists. Some of them showed reasonable oral exposures, and the imidazolone derivatives that showed good oral exposure also exhibited substantially reduced time-dependent CYP3A4 inhibition. Several compounds showed strong in vivo efficacy in our marmoset facial blood flow assay with up to 87% inhibition of CGRP-induced activity. However, oral bioavailability generally remained low, emphasizing the challenges we and others encountered in discovering clinical development candidates for this difficult Class B GPCR target.

Azepino-indazoles as calcitonin gene-related peptide (CGRP) receptor antagonists.

Calcitonin gene-related peptide (CGRP) receptor antagonists have been shown clinically to be effective treatments for migraine. Zavegepant (BHV-3500, BMS-742413) is a high affinity antagonist of the CGRP receptor (hCGRP Ki = 0.023 nM) that has demonstrated efficacy in the acute treatment of migraine with intranasal delivery in a Phase 2/3 trial, despite showing low oral bioavailability in rats (FPO = 1.7%). Using zavegepant as a template, we sought to improve oral bioavailability through a series of azepinones which were designed in an attempt to reduce the number of rotatable bonds. These efforts led to the discovery of compound 21 which was able to mostly maintain high affinity binding (hCGRP Ki = 0.100 nM) and in vivo efficacy in the marmoset facial blood flow assay, while greatly improving oral bioavailability (rat FPO = 17%).

The synthesis and SAR of calcitonin gene-related peptide (CGRP) receptor antagonists derived from tyrosine surrogates. Part 2.

Various substituted indazole and benzoxazolone amino acids were investigated as d-tyrosine surrogates in highly potent CGRP receptor antagonists. Compound 3, derived from the 7-methylindazole core, afforded a 30-fold increase in CGRP binding potency compared with its unsubstituted indazole analog 1. When dosed at 0.03mg/kg SC, compound 2 (a racemic mixture of 3 and its (S)-enantiomer) demonstrated robust inhibition of CGRP-induced increases in mamoset facial blood flow up to 105min. The compound possesses a favorable predictive in vitro toxicology profile, and good aqueous solubility. When dosed as a nasal spray in rabbits, 3 was rapidly absorbed and showed good intranasal bioavailability (42%).

The synthesis and SAR of calcitonin gene-related peptide (CGRP) receptor antagonists derived from tyrosine surrogates. Part 1.

We have systematically studied the effects of varying the central unnatural amino acid moiety on CGRP receptor antagonist potency and CYP inhibition in a series of ureidoamides. In this Letter, we report the discovery of compound 23, a potent CGRP receptor antagonist with only weak CYP3A4 inhibition. Unlike the triptans, compound 23 did not cause active constriction of ex vivo human cerebral arteries. At doses of 0.3-1 mg/kg (s.c.), 23 showed robust inhibition of CGRP-induced increases in marmoset facial blood flow, a validated migraine model. Ureidoamide 23 derives from a novel amino acid, 1H-indazol-5-yl substituted alanine as a tyrosine surrogate.

Discovery of (R)-4-(8-fluoro-2-oxo-1,2-dihydroquinazolin-3(4H)-yl)-N-(3-(7-methyl-1H-indazol-5-yl)-1-oxo-1-(4-(piperidin-1-yl)piperidin-1-yl)propan-2-yl)piperidine-1-carboxamide (BMS-694153): a potent antagonist of the human calcitonin gene-related peptide receptor for migraine with rapid and efficient intranasal exposure.

Calcitonin gene-related peptide (CGRP) has been implicated in the pathogenesis of migraine. Early chemistry leads suffered from modest potency, significant CYP3A4 inhibition, and poor aqueous solubility. Herein, we describe the optimization of these leads to give 4 (BMS-694153), a molecule with outstanding potency, a favorable predictive toxicology profile, and remarkable aqueous solubility. Compound 4 has good intranasal bioavailability in rabbits and shows dose-dependent activity in validated in vivo and ex vivo migraine models.

1-(2-pyrimidinyl)-piperazine, a buspirone metabolite, modulates bladder function in the anesthetized rat.

AIMS: To examine the effects of 1-(2-pyrimidinyl)-piperazine (1-PP), a buspirone metabolite, on bladder function in vivo. METHODS: Micturition reflexes in the rat were evaluated in two models of bladder function; a constant infusion model employing 0.5% acetic acid and an isovolumic model. RESULTS: In the constant infusion model, 1-PP (0.14-1.32 mg/kg) dose-dependently and significantly decreased the number of bladder contractions measured during a 30 min recording period, with little effect on the pressure developed during each contraction. 1-PP is an alpha2-adrenergic receptor antagonist. The alpha2 antagonists BRL44408 (alpha2A vs. alpha2B selective; 0.3 and 1 mg/kg), imiloxan (alpha(2B) vs. alpha2A selective; 1 mg/kg), and yohimbine (non-subtype selective; 1 mg/kg; but not 0.3 mg/kg) also significantly reduced the number of contractions. Vehicle was without effect. In the isovolumic model, 1-PP (0.03-1.0 mg/kg) produced a dose-dependent and significant reduction in the number of bladder contractions recorded during a 15 min assessment period, with the maximum effect observed at 0.3 mg/kg. 1-PP had little effect on blood pressure; the only effect was observed at the highest dose (1 mg/kg) where it produced a transient 17% decrease in pressure. Cromakalim and tolterodine served as comparitors in all studies. CONCLUSIONS: 1-PP decreased the number of bladder contractions evoked by the micturition reflex at doses that had little effect on either the pressure developed during each bladd er contraction or on blood pressure. The effects of 1-PP are likely mediated primarily by alpha2 receptor antagonism.