Beeh KM, et al. - An extrafine formulation of the long-acting muscarinic antagonist, glycopyrronium bromide (GB), developed for delivery via the NEXThaler dry powder inhaler (DPI), was evaluated at different doses in terms of the bronchodilator efficacy and safety in patients with COPD to identify the optimal dose for further development. In this multicenter, randomized, double-blind, placebo-controlled, incomplete block, three-way crossover study, three 28-day treatment periods, each separated by a 21-day washout period, were included. Treatments administered were GB 6.25, 12.5, 25 and 50 μg or matched placebo; all were given twice daily (BID) via DPI, with spirometry assessed on Days 1 and 28 of each treatment period. For patients with COPD, the selection of GB 25 μg BID was supported as the minimal effective dose when delivered with this extrafine DPI formulation.