Efficacy and comfort of olopatadine 0.2% versus epinastine 0.05% ophthalmic solution for treating itching and redness induced by conjunctival allergen challenge

Olopatadine 0.2% (Pataday, Alcon Laboratories Inc., Fort Worth, Texas, USA) and epinastine 0.05% (Elestat, Inspire Pharmaceuticals, Inc., Durham, NC, USA) are topical ocular anti-allergic agents. Both are H(1) antihistamine/mast cell stabilizers indicated for the treatment of ocular itching associated with allergic conjunctivitis.To compare the efficacy and comfort of olopatadine 0.2% with epinastine 0.05%, in the prevention of ocular itching associated with allergic conjunctivitis following conjunctival allergen challenge (CAC).This was a 7 week, four visit, double-masked, randomized, placebo-controlled CAC study. Visit 1 screened subjects for positive ocular allergic responses and Visit 2 confirmed those responses. At Visit 3, 92 subjects were randomized into one of four treatment groups to receive one drop of study medication in each eye: (1) olopatadine 0.2%/placebo, (2) epinastine 0.05%/placebo, (3) olopatadine 0.2%/epinastine 0.05%, (4) placebo/placebo. Subjects were challenged 12 h after drop instillation to evaluate duration of action. At Visit 4, subjects were challenged 5 min after drop instillation to evaluate onset of action. Drop comfort was assessed at Visit 4. MAIN OUTCOME MEASURES;This article focuses on the results of the onset-of-action challenge (Visit 4). At Visit 4, ocular itching was assessed at 3, 5, and 7 min and redness was assessed at 7, 15, and 20 min post-challenge. Drop comfort was assessed upon instillation, at 30s, and at 1, 2, and 5 min post-instillation. Olopatadine 0.2%-treated eyes exhibited significantly lower mean ocular itching scores versus epinastine 0.05%-treated eyes at 5 (p = 0.024) and 7 min (p = 0.003) post-challenge. Olopatadine 0.2%-treated eyes exhibited significantly lower mean redness scores versus epinastine 0.05%-treated eyes at all time points post-challenge (ciliary: por = 0.013, conjunctival: por = 0.015, episcleral: por = 0.006). Olopatadine 0.2% was rated as significantly more comfortable than epinastine 0.05% at 1 min post-drop instillation (p = 0.003). All adverse events were non-serious and unrelated to study medication. Although the CAC model reproduces allergic responses that are not environmentally-induced, patients experience varying severities of responses as are seen in real-world situations.Olopatadine 0.2% was superior to epinastine 0.05% in preventing ocular itching and redness at onset when induced by the CAC model.