A comparison of the speeds of action of salmeterol and salbutamol in reversing methacholine-induced bronchoconstriction.

Abstract We compared the speed of action of the long acting β-agonist salmeterol with that of salbutamol in order to assess whether reported in vitro differences are likely to have clinical significance. We used methacholine tests to produce a standardized level of bronchoconstriction and then observed the rate of recovery of FEV 1 towards baseline after the administration by metered dose inhaler of salmeterol 50 μg or salbutamol 200 μg—doses which are considered to have similar bronchodilator potency. Twenty asthmatic subjects participated, and a double-blind, randomized, cross-over study design was followed. Salmeterol showed a significantly slower speed of action with median recovery to 90% and 95% of the baseline FEV 1 , (pre-methacholine) occurring after 9.6 and 19.4 min, respectively, compared with 4.8 and 8.3 min, respectively, for salbutamol ( P