Montelukast for treating fall allergic rhinitis: effect of pollen exposure in 3 studies.

Background: Montelukast, a potent leukotriene receptor antagonist, is an effective therapy for symptoms of seasonal allergic rhinitis, a disease governed by patients' individual sensitivity and exposure to relevant allergens.

Objective: To evaluate the relationship of montelukast treatment effect vs pollen exposure in studies conducted during 3 consecutive fall allergy seasons.

Method: A combined analysis of these multicenter, randomized, double-blind, parallel-group studies was performed; 1 of the 3 studies is presented for the first time in this article. After a placebo run-in period, 1,862 symptomatic patients were randomly assigned to receive either a 10-mg montelukast tablet (n = 929) or placebo (n = 933) once daily for 2 weeks. Pollen exposure was summarized by mean daily weed pollen count. The interaction between treatment effect and pollen exposure was evaluated on the primary efficacy endpoint and daytime nasal symptom score, as rated by patients; also evaluated was the influence of the timing of the 2-week treatment period relative to the peak of the weed pollen season.

Results: Montelukast significantly improved daytime nasal symptoms score and individual scores of congestion, rhinorrhea, itching, and sneezing compared with placebo. There was a significant interaction (P < .043) between treatment effect and weed pollen exposure; a larger treatment effect was noted in patients exposed to higher pollen counts. An interaction between treatment effect and timing of treatment in relation to peak pollen season was suggested.

Conclusions: Montelukast significantly improved daytime nasal symptoms score in patients with seasonal allergic rhinitis, and the effect was greater in patients exposed to higher pollen levels.