Objective: We hypothesized that children with moderate acute asthma exacerbations receiving oral montelukast with standard therapy will have at least 12% greater forced expiratory volume in 1 second (FEV 1) improvement in 3 hours than those receiving standard therapy alone.

Methods: In this randomized, double-blind, placebo-controlled study, we enrolled emergency patients aged 6 to 14 years with moderate acute asthma exacerbations (peak expiratory flow rate, 40%-70% predicted). Subjects received montelukast 5 mg or placebo orally then standard therapy. We measured FEV 1 before study medication administration and hourly for 3 hours. The primary outcome was FEV 1% predicted change at 3 hours.

Results: At the time of the planned interim analysis, we had enrolled 27 subjects; 23 (11 montelukast, 12 placebo) had a complete FEV 1 data. Both groups had similar mean FEV 1 increases at 3 hours (mean [SD]: montelukast= 16.8%[11.4%], placebo= 19.9%[12.1%]; 95% confidence interval for difference=− 12.22% to 5.95%). Based on further analysis, we determined that enrollment of the planned sample was unlikely to significantly change the results. If our study hypothesis were true, the montelukast group mean FEV 1 increase should be 32% or greater. The probabilities were low that the montelukast sample could be drawn from a normally distributed population with a mean of 32% and that subsequently enrolled montelukast subjects would have sufficient FEV 1 improvements to attain a mean of greater than 32%.

Conclusion: Based on these results, for children aged 6 to 14 years with moderate acute asthma exacerbations, oral montelukast (5 mg) added to standard therapy as in this design is unlikely to result in additional FEV 1 improvements in 3 hours.