PURPOSE: To compare a new ocular antihistamine, emedastine difumarate (Emadine Ophthalmic Solution 0.05%; Alcon Laboratories, Fort Worth, Texas), with the marketed ocular antihistamine, levocabastine hydrochloride (Livostin Ophthalmic Suspension 0.05%; CIBA Vision, Atlanta, Georgia), in the treatment of allergic conjunctivitis after conjunctival allergen challenge.

METHODS: We performed a prospective, double-masked, randomized, contralateral eye study comparing emedastine 0.05% in one eye with levocabastine 0.05% or emedastine vehicle (placebo) in the contralateral eye. Efficacy was determined 10 minutes and 2 hours after administration of study medications. Ocular itching and redness scores were recorded 3, 5, and 10 minutes after conjunctival allergen challenge.

RESULTS: A total of 97 subjects with a history of allergic conjunctivitis and a positive response to a diagnostic test were evaluable for safety analysis, and 91 subjects were evaluable for the efficacy analysis. Emadastine 0.05% was statistically significantly more effective than levocabastine 0.05% in reducing ocular itching after conjunctival allergen challenge in both the 10-minute and the 2-hour challenge (P < .05). Emedastine 0.05% and levocabastine 0.05% were statistically equivalent in reducing conjunctival redness after conjunctival allergen challenge, although emedastine tended to be more efficacious than levocabastine at every observation time point.

CONCLUSIONS: After conjunctival allergen challenge, emadastine 0.05% is significantly more effective than levocabastine 0.05% in reducing ocular itching associated with allergic conjunctivitis. The two compounds are equivalent in controlling the conjunctival redness associated with allergic conjunctivitis.