Comparative efficacy of olopatadine 0.1% ophthalmic solution versus levocabastine 0.05% ophthalmic suspension using the conjunctival allergen challenge model

Objective: To compare the efficacy of olopatadine and levocabastine in reducing ocular allergic itching and vascular hyperemia (redness) induced by conjunctival allergen challenge. Research design and methods: The study was a randomized, double-masked, contralateral study using the conjunctival allergen challenge (CAC) model. At Visit 1, subjects with a positive allergen skin test and a history of allergic conjunctivitis were administered increasing concentrations of allergen until at least a moderate grade 2 ocular itching and conjunctival redness response was obtained in both eyes. Allergic signs were graded on standardized 0-4 scales. Subjects who reacted positively were re-challenged at Visit 2 with the pre-determined concentration of allergen. Subjects who again responded with at least a grade 2 bilateral ocular itching and conjunctival redness score at Visit 2 were eligible for drug evaluation. At Visit 3, subjects received olopatadine in one eye and levocabastine in the contralateral eye according to a computer-generated randomization scheme generated prior to commencement of the study. Ocular discomfort was then graded in both eyes. Subjects were bilaterally challenged with the predetermined concentration of allergen 27 min after topical drug administration, such that the first post-challenge assessment was made 30 min post-drug instillation. Allergic signs and symptoms were evaluated at 3 min, 10 min, and 20 min post-challenge and safety and efficacy analyses were performed. Results: Sixty-eight subjects received study drug and were included in the safety and efficacy analyses. Ocular itching scores for olopatadine were significantly lower than levocabastine at 3 min and 10 min post-challenge (p < 0.001). Ocular redness scores for olopatadine were significantly lower than levocabastine at all time points post-challenge (p < 0.0001). Of all subjects, 4.41% reported ocular discomfort in the olopatadine eye and 26.5% in the levocabastine treated eye. Conclusion: Olopatadine treated eyes had significantly less itching and redness than levocabastine treated eyes after conjunctival allergen challenge. Olopatadine was also associated with less discomfort upon instillation than levocabastine.