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

ABSTRACT

Background: 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 H₁ antihistamine/mast cell stabilizers indicated for the treatment of ocular itching associated with allergic conjunctivitis.

Objective: 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).

Research design and methods: 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; results: 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 30?s, 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: p ≤ 0.013, conjunctival: p ≤ 0.015, episcleral: p ≤ 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.

Conclusion: Olopatadine 0.2% was superior to epinastine 0.05% in preventing ocular itching and redness at onset when induced by the CAC model.