Inhaled, long-acting bronchodilators represent a cornerstone of maintenance treatment for chronic obstructive pulmonary disease (COPD). Aclidinium bromide/formoterol fumarate 400/12 μg fixed-dose combination (FDC) has recently been licensed for use in adults with COPD in the European Union. This phase 1, randomized, open-label, 3-way, complete crossover, single-dose study assessed the pharmacokinetics, safety, and tolerability of an FDC, aclidinium bromide 400 μg, and formoterol fumarate 12 μg, all administered via Genuair™ to 30 healthy subjects. The rate and extent of absorption were comparable for aclidinium/formoterol FDC and individual monotherapies; aclidinium/formoterol FDC and aclidinium alone: Cmax , 270 and 215 pg/mL, respectively; AUC0-t , 229 and 222 pg · h/mL, respectively; aclidinium/formoterol FDC and formoterol alone: Cmax , 11 and 9.3 pg/mL, respectively; AUC, 36 and 32.4 pg · h/mL, respectively. There were no major differences in relative bioavailability between the combination and monotherapies: the aclidinium Cmax and AUC0-t were 26% and 3% higher, respectively, with aclidinium/formoterol FDC compared with aclidinium alone, and 18% and 11% higher, respectively, compared with formoterol alone. Aclidinium/formoterol FDC was well tolerated; the incidence of adverse events was low and similar to the monotherapies. Aclidinium/formoterol FDC was not associated with any major differences in rate and extent of absorption or relative bioavailability compared with monotherapies.