This was a 4-week, randomized, open-label, two-period crossover study in patients with COPD. Patients were randomized 1:1 to receive albuterol via metered dose inhaler followed by ipratropium or vice versa during treatment Period 1 (10–14 days). The order of treatments was then reversed during treatment Period 2 (10–14 days). Pre-defined efficacy endpoints were: forced expiratory volume in 1 s (FEV1), derived FEV1, inspiratory capacity (IC) and daily variability of FEV1 and IC as measured by coefficient of variation (CV).