Clinical Studies of Combination Montelukast and Loratadine in Patients with Seasonal Allergic Rhinitis

Background. Concomitant use of montelukast and loratadine may improve symptoms of seasonal allergic rhinitis (SAR) more than treatment with either drug alone. Objective. We compared the efficacy of this combination versus placebo, nasal beclomethasone, montelukast, and loratadine in study 1 and versus placebo, montelukast, and loratadine in study 2. Methods. Patients were randomly allocated to double-blind treatment with intranasal beclomethasone 200 mu g/twice daily (study 1 only), placebo, montelukast 10 mg+loratadine 10 mg, montelukast 10 mg, or loratadine 10 mg once daily. The primary endpoint was the Composite Symptom Score (CSS): average of daily diary scores for Daytime Nasal Symptoms and Nighttime Symptoms. Results. In study 1, improvements in the change from baseline in CSS were seen for montelukast+loratadine (least-squares means [95% CI]= -0.43 [-0.51, -0.35]), beclomethasone (-0.57 [-0.64, -0.49]), montelukast, and loratadine. All treatments were significantly better than placebo; montelukast+loratadine had a significantly greater effect on CSS than montelukast alone but no difference compared to loratadine was detected. Beclomethasone provided significantly greater improvement versus montelukast+loratadine on the primary and secondary endpoints except for the rhinoconjunctivitis quality-of-life score. In study 2, the combination treatment was similar to montelukast, loratadine, and placebo for the primary and secondary endpoints. Conclusion. In study 1, montelukast+loratadine had a significantly greater effect on CSS than placebo and montelukast alone; however, in all comparisons, nasal beclomethasone had a greater effect on daily symptoms. In contrast, the combination of montelukast+loratadine in study 2 did not provide greater improvement compared with placebo, montelukast, or loratadine monotherapy, perhaps due to a large placebo effect.