Safety, Tolerability and Pharmacokinetics and Pharmacodynamics of Inhaled Once-Daily Umeclidinium in Healthy Adults Deficient in CYP2D6 Activity: A Double-Blind, Randomized Clinical Trial

Background Umeclidinium is a new, long-acting, muscarinic receptor antagonist currently in development for the treatment of chronic obstructive pulmonary disease (COPD). In vitro cell culture data suggest that up to 99 % of umeclidinium is potentially metabolized by cytochrome P450 2D6 (CYP2D6), but without a definitive human metabolism radiolabel study, the extrapolation of in vitro to in vivo is only an estimate.