Pharmacokinetics of Glycopyrronium Following Repeated Once-Daily Inhalation in Healthy Chinese Subjects

Background and Objectives Glycopyrronium is a once-daily long-acting muscarinic antagonist for the maintenance treatment of patients with chronic obstructive pulmonary disease. This study assessed the pharmacokinetics of inhaled glycopyrronium 50 µg once-daily for 14 days in healthy Chinese subjects. Methods In this open-label study, 12 Chinese healthy subjects (six males and six females; mean age 23.1 years [range 18–26 years]) were enrolled and completed the study. Glycopyrronium in plasma was determined using validated liquid chromatography–mass spectrometry method with a lower limit of quantification of 1.5 pg/mL. Plasma pharmacokinetic parameters were determined on Day 1 after first dose and on Day 14 (steady state) after last dose using non-compartmental analysis. Trough pharmacokinetic samples (Days 5, 7, 10 and 12) were collected. Safety was also assessed. Results Glycopyrronium was rapidly absorbed into the systemic circulation after inhalation and its plasma concentrations decreased rapidly thereafter. Median time to reach maximum concentration ( T max ) was reached within 5 min after inhalation on both Days 1 and 14. Accumulation in the systemic exposure to glycopyrronium was observed from the time of first dose administration on Day 1 up to Day 14 and the observed accumulation ratio ( R acc ) values of area under the plasma drug concentration–time curve [AUC] from time 0 to 24 h post-dose (AUC 0–24h ) and maximum plasma drug concentration ( C max ) (Day 14/Day 1) were 2.77 and 1.59, respectively. The elimination half-life ( T 1/2 ) was not reported. Mean effective half-life ( T 1/2,acc ) was 37.7 h. Pharmacokinetic steady state was reached after 5 days of daily dosing. One subject experienced dry mouth; otherwise glycopyrronium was well tolerated. Conclusions Comparison of systemic exposure to glycopyrronium in Chinese versus the non-Chinese population did not indicate clinically relevant ethnic differences. Multiple inhaled doses of glycopyrronium were safe and well tolerated.