Evaluation of Montelukast for the Treatment of Children With Japanese Cedar Pollinosis Using an Artificial Exposure Chamber (OHIO Chamber)

Background This study evaluated the efficacy of montelukast in reducing seasonal allergic rhinitis symptoms in Japanese children with Japanese cedar (JC) pollinosis induced in an artificial exposure chamber (OHIO Chamber). Methods Pediatric patients aged 10 to 15 years sensitive to JC pollen entered a randomized, double-blind, single-site, crossover study. After confirmation of an allergic response to a JC pollen exposure for 3 hours in the OHIO Chamber during the screening period, subjects received either montelukast 5 mg chewable tablets or placebo for a 7-day treatment period, followed by a 3-hour pollen exposure in the chamber. After a 7-day washout period, subjects crossed over to the other treatment. Subjects were instructed to self-assess their nasal symptoms using 5-point scale for every 30 minutes. The primary end point was the change from baseline (just before entering the exposure chamber for each exposure) in total nasal symptom score (TNSS; the sum of nasal congestion, nasal discharge, and sneezing scores) over 3 hours of pollen exposure. Adverse events (AEs) were evaluated throughout the study. Results A total of 220 subjects (median age, 12 years) received treatment. For TNSS, the between-group difference in the change (95% confidence interval) was −0.01 (−0.11 to 0.10); the change between placebo and montelukast 5 mg was not significant. TNSS in the screening and treatment periods after receiving placebo for 7 days was 1.58 and 1.31, respectively, suggesting a placebo response. On account of high placebo response, a post hoc analysis was conducted. The analysis in a subgroup of subjects who did not show placebo response demonstrated a difference in the efficacy between montelukast and placebo (nominal P