Safety and tolerability of aclidinium administered intravenously and absolute bioavailability of inhaled aclidinium in healthy male participants.

Aclidinium bromide is a long-acting muscarinic antagonist in development for chronic obstructive pulmonary disease treatment. This 2-part, phase I study evaluated the safety and tolerability of single ascending intravenous (IV) doses of aclidinium to determine its maximum tolerated dose (MTD; part I) and its absolute bioavailability (part II). Healthy male participants (N = 24) were randomized (1:1) in each part: 3-period crossover, placebo-controlled, single-ascending, alternating IV doses of aclidinium (25-400 µg) in part I and 2-period crossover, single-alternating IV and inhaled doses of aclidinium (200 µg) in part II. A ≥7-day washout separated treatment periods. Pharmacokinetic data were collected in both parts. Following IV or inhaled aclidinium, time to reach maximum plasma concentration following drug administration (t(max) ) was 5 to 7 minutes for all doses. After maximum plasma drug concentration (C(max)), aclidinium was rapidly cleared from plasma. Aclidinium absolute bioavailability was <5% following a single inhaled 200-µg dose. Urinary excretion of unchanged aclidinium was very low, with a greater amount of inactive metabolites excreted compared with aclidinium, all of which were recovered within 12 hours postdose. The MTD following IV administration was not reached; all single IV (25-400 µg) and inhaled doses (200 µg) were well tolerated. In conclusion, the low and short-lived bioavailability of aclidinium and the low incidence of systemic side effects contribute to its positive safety and tolerability profile.