Montelukast is recommended to be taken in the evening. The effectiveness of this drug to prevent exercise-induced bronchoconstriction (EIB) in children was already evaluated. However, there is no information to determine if this effectiveness could vary depending on dosage time. Children (n = 24) with a documented history of EIB performed an exercise challenge test before starting montelukast treatment. Twelve children were randomly allocated to receive the drug in the morning for 2 weeks, and another 12 to receive it in the evening. After this treatment period and after a week of washout, the children were crossed over. An exercise test was repeated after the first and second periods of treatment. Values obtained after morning or evening dosage were compared with pretreatment values for the whole group of children. There was a significant effect of montelukast for protecting against EIB, measured both as percent of maximum fall in forced expired volume in 1 sec (FEV1) (18.9 +/- 9.7, morning, 18.7 +/- 11.3, evening, vs. 27.5 +/- 9.8, pretreatment; P < 0.05) or as area under the curve (156.4 +/- 102.0, morning, 145.4 +/- 130.6, evening, vs. 294.3 +/- 156.5, pretreatment; P < 0.005). There were no statistical differences between taking the drug in the morning or evening. In conclusion, montelukast, taken for 2 weeks, is equally effective in exercise-induced bronchoconstriction when dosing either in the morning or in the evening.
(c) 2006 Wiley-Liss, Inc.