RT Journal Article SR Electronic T1 Biotransformation of Daclatasvir In Vitro and in Nonclinical Species: Formation of the Main Metabolite by Pyrrolidine δ-Oxidation and Rearrangement JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP 809 OP 820 DO 10.1124/dmd.115.068866 VO 44 IS 6 A1 Wenying Li A1 Weiping Zhao A1 Xiaohong Liu A1 Xiaohua Huang A1 Omar D. Lopez A1 John E. Leet A1 R. Marcus Fancher A1 Van Nguyen A1 Jason Goodrich A1 John Easter A1 Yang Hong A1 Janet Caceres-Cortes A1 Shu Y. Chang A1 Li Ma A1 Makonen Belema A1 Lawrence G. Hamann A1 Min Gao A1 Mingshe Zhu A1 Yue-Zhong Shu A1 W. Griffith Humphreys A1 Benjamin M. Johnson YR 2016 UL http://dmd.aspetjournals.org/content/44/6/809.abstract AB 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.