Long-term circadian effects of salmeterol in asthmatic children treated with inhaled corticosteroids.

The present study was set up to investigate whether salmeterol in children with asthma already treated with inhaled corticosteroids (ICS) leads to a sustained bronchodilator effect and decreased bronchial responsiveness, both during the day and night. Furthermore, we investigated whether cessation of salmeterol leads to a rebound increase in bronchial responsiveness. Forty children with asthma (aged 7-15 yrs) using ICS participated in a randomized, double-blind, parallel study. They received either twice daily 50 micrograms salmeterol or placebo. FEV1 and provocative concentration of methacholine that caused a 20% fall in FEV1 (PC20) were measured at 4:00 P.M. and 4:00 A.M. at baseline and after 16 wk. The same measurements were performed at 4:00 P.M. at 8 h after the first dose, and after 1 and 8 wk. After cessation of the study drug, FEV1 and PC20 were measured at 12 and 20 h and after 1 wk. Overall mean FEV1 from 1 to 16 wk of treatment was significantly higher in the salmeterol group than in the placebo group (difference, 4.9 +/- 2.0%, p = 0.01). Evolution in time of FEV1 did not differ significantly between the two groups (p = 0.09). Overall mean PC20 from 1 to 16 wk of treatment was not significantly higher with salmeterol than with placebo (difference, 0.7 +/- 0.4 doubling dose [DD] p = 0.07); evolution in time of PC20 did not differ significantly between the two groups (p = 0.58).(ABSTRACT TRUNCATED AT 250 WORDS)