Activity of aclidinium bromide, a new long-acting muscarinic antagonist: a phase I study.

AIM Aclidinium bromide is a muscarinic antagonist in development for the treatment of chronic obstructive pulmonary disease (COPD). This phase I trial in healthy subjects investigated the bronchodilator activity of aclidinium and its ability to reduce methacholine-induced bronchoconstriction. METHODS This double-blind, partial-crossover study randomized 12 subjects to treatment with single doses of aclidinium (50, 300 or 600 microg) or placebo. Drug activity was assessed for 24 h after administration by specific airway conductance (sGaw), airways resistance (Raw) and bronchial responsiveness (PC35 sGaw methacholine). RESULTS Aclidinium significantly increased sGaw compared with placebo at all assessments and doses (sGaw mean +/- SD AUC (l kPa(-1) h) for placebo 24.4 +/- 4.37, for 50 microg 29.0 +/- 7.08, for 300 microg 31.2 +/- 6.68 and for 600 microg 32.7 +/- 7.95) (P < 0.009), except 50 microg at 1 and 24 h. Significant decreases in Raw were observed with aclidinium 300 and 600 microg compared with placebo at all assessments (Raw mean +/- SD AUC (kPa s(-1) l(-1) h) for placebo 7.7 +/- 3.46, for 300 microg 5.8 +/- 2.33, for 600 microg 6.3 +/- 3.11) (P < 0.04) except 600 microg at 24 h. Differences between aclidinium 300 and 600 microg vs. placebo in PC35 doubling concentration were significant at all assessments (mean +/- SD AUC (mg ml(-1) h) for placebo 100.0 +/- 30.27, for 50 microg 117.2 +/- 33.33, for 300 microg 168.9 +/- 28.66 and for 600 microg 179.1 +/- 15.73 (P < 0.0001). For all endpoints, there was a significant difference between aclidinium 50 microg and the higher doses (P < 0.0001). Aclidinium was not detected in plasma and was well tolerated. CONCLUSION Aclidinium produced statistically significant and sustained bronchodilation over 24 h, suggesting long-acting efficacy and providing a rationale for future studies in patients with COPD.