Time efficacy of a single dose of montelukast on exercise-induced asthma in children

The aim of this study was to evaluate the timing of onset and the duration of action of a single oral-dose treatment with montelukast in comparison to placebo on exercise-induced asthma (EIA) in asthmatic children. Nineteen children (7-13 years) with stable asthma were evaluated. Patients undertook three consecutive treadmill exercise tests, respectively, 2, 12 and 24 h after a single-dose administration. A double-blind randomized, single-dose, placebo-controlled, crossover design was used. To assess bronchoconstriction after the exercise challenge, the maximal percentage fall in FEV1 (DeltaFEV(1) ) from the baseline value was considered. Two hours after dosing, DeltaFEV(1) was -15.33+/-2.93 for placebo and -13.33+/-2.03 for montelukast. At 12 h, DeltaFEV(1) was -18.69+/-2.83 for placebo, -9.78+/-1.85 for montelukast (p<0.005). No difference was observed between placebo (DeltaFEV(1) -10.21+/-2.07) and montelukast (DeltaFEV(1) -9.10+/-2.02) at 24 h. Analysis of the degree of protection showed a significant efficacy of montelukast (p=0.02) in comparison with placebo only at 12 h. Montelukast showed a significant protective effect 12 h after dosing, but no effect after 2 and 24 h. In mild asthmatics, the timing of administration of single dosage before exercise should be strictly considered in order to obtain the drug protective effects.