292 DURATION OF ACTION OF FORMOTEROL AND SALBUTAMOL DRY-POWDER INHALATION IN PREVENTION OF EXERCISE-INDUCED ASTHMA IN CHILDREN

Abstract

The duration and degree of the preventative effect of a single dose formoterol 12μg and salbutamol .400μg dry-powder against exercise-induced asthma (EIA) was compared in a randomised, double-blind, placebo-controlled study. Sixteen children (10-14 yrs) with EIA and a maximal fall in FEV1 of 38% (median, range:22-79%) were included in the study. On each of 3 different days they inhaled either formoterol 12μg or salbutamol 400μg or placebo dry-powder from an ISF device. A standardized submaximal treadmill exercise challenge test was performed 3 and 12 hours after inhalation. The degree of preventative effect of active drug was calculated as 100*(EIAp - EIAa)/EIAp %, where EIAp and ElAa are the maximal median fall in FEVl on active drug and placebo days respectively. Formoterol afforded 72% (p−0.0001) preventative effect at 3 hours and 69% (p−0.0001) at 12 hours post inhalation compared to 49% (p−0.0001) and 19% (ns) preventative effect when salbutamol was used. At the first exercise test there was no difference between formoterol and salbutamol (p−0.0551), while the difference became evident at the second exercise test after which formoterol was superior to salbutamol (p−0.0011) in degree of preventative effect against EIA. No side effects were observed. Conclusion: Formoterol 12μg dry-powder inhaled from an ISF device affords a clinically relevant preventative effect against EIA for a duration of at least 12 hours.