Duration of action of formoterol and salbutamol dry-powder inhalation in prevention of exercise-induced asthma in children.

The aim of this study was to evaluate the effect and tolerability of formoterol 12 micrograms on exercise-induced asthma in children for 12 h as compared to the effect of salbutamol 400 micrograms and placebo. The drugs were inhaled as dry powder from a flow-dependent metered-dose inhaler (DP-MDI). Sixteen asthmatic children took part in a double-blind placebo-controlled within-patient single-centre trial. On each study day the patients were given one of the drugs or placebo in random order, and standardized exercise tests were performed after 3 and 12 h. At a pretrial test the children had demonstrated a median maximum percentage fall of 38% (range 22-79%) in forced expiratory volume in 1 s after exercise challenge. Formoterol showed a median percentage protection of 77% and 70% at 3 and 12 h postexercise, respectively, as compared to 46% and 13% with salbutamol. No side-effects were observed. Formoterol 12 micrograms administered as dry powder offers significantly better protection against exercise-induced asthma after 3 and 12 h as compared to salbutamol 400 micrograms and placebo.