Identification of potent and selective oxytocin antagonists. Part 1:indole and benzofuran derivatives

Studies to discover novel, potent and selective oxytocin antagonists are reported. Combinatorial libraries designed to find novel replacements of fragments of oxytocin antagonist L-371,257, identified pyrimidine, thiazole, indole and benzofuran as potential alternatives to the benzoic acid moiety of L-371,257. Additional investigations identified indole and benzofuran derivatives with potent oxytocin antagonist activity

Identification of potent and selective oxytocin antagonists. Part 2: further investigation of benzofuran derivatives

The paper covers continuing efforts to discover novel, potent and selective oxytocin antagonists. Further benzofuran derivatives with potent oxytocin antagonist activity and good pharmacokinetic parameters are reported. Efforts to improve the in vivo activity of the series are described

Integration of Lead Optimization with Crystallography for a Membrane-Bound Ion Channel Target: Discovery of a New Class of AMPA Receptor Positive Allosteric Modulators

A novel series of AMPAR positive modulators is described that were identified by high throughput screening. The molecules of the series have been optimized from a high quality starting point hit to afford excellent developability, tolerability, and efficacy profiles, leading to identification of a clinical candidate. Unusually for an ion channel target, this optimization was integrated with regular generation of ligand-bound crystal structures and uncovered a novel chemotype with a unique and highly conserved mode of interaction via a trifluoromethyl group

Pyridyl-2,5-Diketopiperazines as Potent, Selective, and Orally Bioavailable Oxytocin Antagonists: Synthesis, Pharmacokinetics, and In Vivo Potency

A six-stage stereoselective synthesis of indanyl-7-(3′-pyridyl)-(3<i>R</i>,6<i>R</i>,7<i>R</i>)-2,5-diketopiperazines oxytocin antagonists from indene is described. SAR studies involving mono- and disubstitution in the 3′-pyridyl ring and variation of the 3-isobutyl group gave potent compounds (p<i>K</i>_i > 9.0) with good aqueous solubility. Evaluation of the pharmacokinetic profile in the rat, dog, and cynomolgus monkey of those derivatives with low cynomolgus monkey and human intrinsic clearance gave 2′,6′-dimethyl-3′-pyridyl <i>R</i>-<i>sec</i>-butyl morpholine amide Epelsiban (<b>69</b>), a highly potent oxytocin antagonist (p<i>K</i>_i = 9.9) with >31000-fold selectivity over all three human vasopressin receptors hV1aR, hV2R, and hV1bR, with no significant P450 inhibition. Epelsiban has low levels of intrinsic clearance against the microsomes of four species, good bioavailability (55%) and comparable potency to atosiban in the rat, but is 100-fold more potent than the latter in vitro and was negative in the genotoxicity screens with a satisfactory oral safety profile in female rats