Characterizing the Metabolic Fate and Pharmacokinetics of the RyR2 Inhibitor ent-Verticilide

Abstract

ent-Verticilide is a synthetic macrocyclic depsipeptide and ryanodine receptor 2 (RyR2) inhibitor with potential therapeutic applications in cardiac arrhythmias. This study characterized its in vitro metabolism and in vivo pharmacokinetics to better understand factors that may influence its disposition. Metabolic stability was evaluated in mouse, rat, dog, and human liver S9 fractions, followed by CYP reaction phenotyping in human liver microsomes and metabolite profiling in human and rat liver S9 fractions. Pharmacokinetics were evaluated in rats following intravenous and oral administration. ent-Verticilide underwent rapid, NADPH-dependent depletion across all species, with in vitro half-lives ranging from 2.1 to 5.3 min. CYP reaction phenotyping indicated that CYP3A was the predominant CYP subfamily involved in its metabolism. Eight putative metabolites were identified in human and rat liver S9, primarily resulting from hydroxylation, oxidation, and desaturation, with generally similar metabolite profiles between species. In rats, ent-verticilide exhibited a systemic clearance of 29.6 mL/min/kg, a steady-state volume of distribution of 4.86 L/kg, and a terminal half-life of 6.85 h following intravenous administration. Absolute oral bioavailability was 10.5%. Overall, these findings show that ent-verticilide undergoes extensive oxidative hepatic metabolism and provide an initial DMPK framework for its continued preclinical development.