Table 4

Potency and duration of action of aclidinium, ipratropium, and tiotropium in isolated guinea pig trachea

pA₂ values were determined by Schild plot analysis using carbachol (0.1 nM–1 mM) as the contractile agent. Antagonists were incubated for 30 min before a concentration-response curve of cholinergic agonists was generated. The concentration ranges of the antagonists used were aclidinium (0.1–100 nM), ipratropium (1–100 nM), and tiotropium (1–10 nM). Data are reported as the mean ± S.E. One-way analysis of variance of pA₂ values showed no significant differences. In the duration of action studies, contraction of isolated guinea pig trachea was induced by carbachol (10 μM). Antagonists were added at the concentrations indicated and were washed out after a period of time (30-min carbachol-contraction assay). Duration of action was calculated as the time from antagonist washout to recovery of 50% (t_1/2) or maximal recovery (t_max) of the maximal contraction induced by carbachol. Data are reported as mean ± S.E.