Concomitant montelukast and loratadine as treatment for seasonal allergic rhinitis: A randomized, placebo-controlled clinical trial

Background: Nasal challenge studies have suggested histamine and cysteinyl leukotrienes are important proinflammatory mediators in allergic rhinitis. This study was designed to determine the efficacy of montelukast, a cysteinyl leukotriene receptor antagonist, administered alone or concomitantly with loratadine, an H-1-receptor antagonist, in seasonal allergic rhinitis. Objective: The purpose of this study was to determine the effect of concomitant use of montelukast and loratadine in the treatment of seasonal allergic rhinitis. Methods: In this multicenter (N = 12) double-blind, randomized, parallel-group, placebo-controlled 2-week trial, 460 men and women, aged 15 to 75 years, with spring seasonal allergic rhinitis were randomly allocated to receive 1 of the following 5 treatments: montelukast 10 or 20 mg, loratadine 10 mg, montelukast 10 mg with loratadine 10 mg, or placebo, once daily in the evening. The primary end point was daytime nasal symptoms score (average of congestion, rhinorrhea, itching, and sneezing). Other end points were eye symptoms, nighttime symptoms, individual daytime nasal symptoms, global evaluations (patient's and physician's), and rhinoconjunctivitis quality-of-life scores. Results: Concomitant montelukast with loratadine improved the primary end point significantly (P < .001) compared with placebo and each agent alone. Compared with placebo, montelukast with loratadine also significantly improved eye symptoms, nighttime symptoms, individual daytime nasal symptoms, global evaluations, and quality of life. Montelukast alone and loratadine alone caused modest improvements in rhinitis end points. All treatments were similarly well tolerated. Conclusions: Concomitant montelukast with loratadine provided effective treatment for seasonal allergic rhinitis and associated eye symptoms with a safety profile comparable with placebo.