A randomized, double-blind, placebo-controlled comparison of emedastine 0.05% ophthalmic solution with loratadine 10 mg and their combination in the human conjunctival allergen challenge model

Abstract

Background: When selecting treatment for allergic conjunctivitis, a primary concern is whether to choose local or systemic therapy. Objective: This study compared the efficacy of topical emedastine 0.05% ophthalmic solution with that of oral loratadine 10 mg and their combination in the conjunctival allergen challenge model of allergic conjunctivitis. Methods: This was a single-center, randomized, double-masked, placebo-controlled, parallel-group study. At visit 1, eligible subjects underwent conjunctival allergen challenge to identify the dose required to elicit a positive allergic reaction. After 7 days, subjects returned for visit 2, at which the allergen dose was confirmed. At visit 3, which took place 2 weeks later, subjects were randomized to receive either emedastine plus placebo capsules, loratadine plus placebo eyedrops, or both emedastine and loratadine. One hour after receiving study drug, subjects were challenged with allergen in both eyes. Allergic signs and symptoms were graded using standardized 5-point scales. The primary efficacy variables were itching and conjunctival hyperemia. Secondary efficacy variables were ciliary and episcleral hyperemia, chemosis, lid swelling, and tearing. Itching was graded subjectively at 3, 5, and 10 minutes after challenge. All other variables were assessed at 5, 10, and 20 minutes after challenge. Results: Eighty subjects (mean age, 43.68 years) were randomized to receive study treatment. Forty subjects (20 men, 20 women) received emedastine plus placebo capsules, 20 (7 men, 13 women) received loratadine plus placebo eyedrops, and 20 (12 men, 8 women) received both active treatments. In the between-group efficacy comparison at visit 3, the difference in itching and hyperemia scores between emedastine and loratadine was statistically significant at all time points (all, P < 0.05). Efficacy scores for the combination of emedastine and loratadine were significantly better than those for loratadine alone at 2 of 3 time points for itching and all time points for hyperemia ( P < 0.05). The combination was significantly better than emedastine alone at 1 of 3 time points for itching and 6 of 9 time points for hyperemia ( P < 0.05). Conclusion: In this study, emedastine was more efficacious than loratadine for reducing the itching and redness associated with allergic conjunctivitis in the human conjunctival allergen challenge model.