Biotransformation of Daclatasvir In Vitro and in Nonclinical Species: Formation of the Main Metabolite by Pyrrolidine δ-Oxidation and Rearrangement.

Daclatasvir is a first-in-class, potent, and selective inhibitor of the hepatitis C virus nonstructural protein 5A replication complex. In support of nonclinical studies during discovery and exploratory development, liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance were used in connection with synthetic and radiosynthetic approaches to investigate the biotransformation of daclatasvir in vitro and in cynomolgus monkeys, dogs, mice, and rats. The results of these studies indicated that disposition of daclatasvir was accomplished mainly by the release of unchanged daclatasvir into bile and feces and, secondarily, by oxidative metabolism. Cytochrome P450s were the main enzymes involved in the metabolism of daclatasvir. Oxidative pathways included δ-oxidation of the pyrrolidine moiety, resulting in ring opening to an aminoaldehyde intermediate followed by an intramolecular reaction between the aldehyde and the proximal imidazole nitrogen atom. Despite robust formation of the resulting metabolite in multiple systems, rates of covalent binding to protein associated with metabolism of daclatasvir were modest (55.2-67.8 pmol/mg/h) in nicotinamide adenine dinucleotide phosphate (reduced form)-supplemented liver microsomes (human, monkey, rat), suggesting that intramolecular rearrangement was favored over intermolecular binding in the formation of this metabolite. This biotransformation profile supported the continued development of daclatasvir, which is now marketed for the treatment of chronic hepatitis C virus infection.

Disposition and metabolism of [14C]brasofensine in rats, monkeys, and humans.

Brasofensine is an inhibitor of the synaptic dopamine transporter. These studies were conducted to characterize the pharmacokinetics, absolute bioavailability, disposition, and metabolism of brasofensine after i.v. and/or p.o. administrations of [(14)C]brasofensine in rats (1.5 mg/kg i.v., 4 mg/kg p.o.) and monkeys (4 mg i.v., 12 mg p.o.) and humans (50 mg p.o.). Brasofensine was rapidly absorbed after p.o. administration in rats and monkeys, with peak plasma concentrations occurring 0.5 to 1 h but 3 to 8 h for brasofensine in humans. Plasma terminal elimination half-lives were approximately 2 h in rats, approximately 4 h in monkeys, and approximately 24 h in humans. Total body clearance and steady-state volume of distribution values were 199 ml/min/kg and 24 l/kg, respectively, in the rat and 32 ml/min/kg and 46 l/kg, respectively, in the monkey. Absolute bioavailability was 7% in rats and 0.8% in monkeys. After a single p.o. dose, urinary excretion of radioactivity accounted for 20% of the administered dose in rats, 70% in monkeys, and 86% in humans, with the remainder excreted into the feces. Brasofensine had extensive first-pass metabolism following p.o. administration in humans, monkeys, and rats. It primarily underwent O- and N-demethylation and isomerization. Some of the desmethyl metabolites were further converted to glucuronides. These primary metabolites and glucuronides of demethyl brasofensine (M1 and M2) were major circulating metabolites in humans and were also observed in rat and monkey plasma.

Discovery and preclinical profile of Saxagliptin (BMS-477118): a highly potent, long-acting, orally active dipeptidyl peptidase IV inhibitor for the treatment of type 2 diabetes.

Efforts to further elucidate structure-activity relationships (SAR) within our previously disclosed series of beta-quaternary amino acid linked l-cis-4,5-methanoprolinenitrile dipeptidyl peptidase IV (DPP-IV) inhibitors led to the investigation of vinyl substitution at the beta-position of alpha-cycloalkyl-substituted glycines. Despite poor systemic exposure, vinyl-substituted compounds showed extended duration of action in acute rat ex vivo plasma DPP-IV inhibition models. Oxygenated putative metabolites were prepared and were shown to exhibit the potency and extended duration of action of their precursors in efficacy models measuring glucose clearance in Zucker(fa/fa) rats. Extension of this approach to adamantylglycine-derived inhibitors led to the discovery of highly potent inhibitors, including hydroxyadamantyl compound BMS-477118 (saxagliptin), a highly efficacious, stable, and long-acting DPP-IV inhibitor, which is currently undergoing clinical trials for treatment of type 2 diabetes.

Design and synthesis of N-[(4-methoxyphenoxy)carbonyl]-N-[[4-[2-(5- methyl-2-phenyl-4-oxazolyl)ethoxy]phenyl]methyl]glycine [Muraglitazar/BMS-298585], a novel peroxisome proliferator-activated receptor alpha/gamma dual agonist with efficacious glucose and lipid-lowering activities.

Muraglitazar/BMS-298585 (2) has been identified as a non-thiazolidinedione PPAR alpha/gamma dual agonist that shows potent activity in vitro at human PPARalpha (EC(50) = 320 nM) and PPARgamma(EC(50) = 110 nM). Compound 2 shows excellent efficacy for lowering glucose, insulin, triglycerides, and free fatty acids in genetically obese, severely diabetic db/db mice and has a favorable ADME profile. Compound 2 is currently in clinical development for the treatment of type 2 diabetes and dyslipidemia.