Therapeutic effect of montelukast, a cysteinyl leukotriene receptor 1 antagonist, on Japanese patients with seasonal allergic rhinitis.

BACKGROUND Secretion of nasal discharge was enhanced and airway-resistance in the nasal cavity was augmented, resulting in nasal congestion, when leukotrienes were administered to the nasal mucosa. These results indicate that leukotrienes play an important role in the pathogenesis of allergic rhinitis. METHODS A double-blind clinical study was carried out to evaluate the efficacy and the safety of montelukast, a cysteinyl leukotriene receptor 1 antagonist, 5 mg, 10 mg or placebo orally administered once daily at bedtime for 2 weeks, to Japanese patients with seasonal allergic rhinitis. The composite nasal symptom scores (average over the 2-week treatment period) were compared among the montelukast 5 mg and 10 mg groups with the placebo group. RESULTS The composite nasal symptom score significantly improved in the montelukast 5 mg and 10 mg groups compared with the placebo group. The administration of montelukast 5 mg or 10 mg once daily was well tolerated and the safety profiles were similar to those of the placebo. There were no significant differences in the incidences of adverse experience or drug-related adverse experience among the montelukast 5 mg, 10 mg groups and the placebo group. CONCLUSIONS Both montelukast 5 mg and 10 mg doses show clinically meaningful efficacy for the treatment of patients with seasonal allergic rhinitis and the safety profiles of those are comparable to that of the placebo.