Background: Olopatadine hydrochloride 0.1% ophthalmic solution and azelastine hydrochlofide 0.05% ophthalmic solution are 2 topical antiallergic agents indicated for the treatment of itching of the eye associated with allergic conjunctivitis. Olopatadine has recently received US Food and Drug Administration (FDA) approval for an expanded indication for the treatment of signs and symptoms of allergic conjunctivitis, including itching, tearing, eyelid swelling, redness, and chemosis.
Objective: The purpose of this study was to compare the efficacy of olopatadine hydrochloride versus azelastine hydrochloride and placebo (artificial tears) in the conjunctival allergen challenge (CAC) model.
Methods: This was a prospective, randomized, double-masked, contralaterally controlled, multicenter, allergen-challenge study. Itching was chosen as the primary efficacy variable since it is the only FDA-approved indication these 2 agents have in common. Subjects with a history of allergic conjunctivitis who responded to the CAC at screening visits 1 and 2 were randomized to 1 of 3 treatment groups: olopatadine in 1 eye and azelastine in the other eye; olopatadine in 1 eye and placebo in the other eye; or azelastine in 1 eye and placebo in the other eye. At the assessment visit (visit 3), subjects received masked study medication according to the randomization scheme. After 5 minutes, subjects were bilaterally challenged with the allergen concentration that had elicited a positive conjunctival allergic response at visits 1 and 2. Immediately after challenge, subjects gave itching assessments (scale, 0 = no itching to 4 = severe itching) every 30 seconds for a total period of 20 minutes. Mean itching scores for all eyes were compared by treatment. Mean itching scores at each time point were compared between treatments using 2 sample t tests.
Results: Of the 180 subjects screened, 111 responded to the CAC at visits 1 and 2 and completed the study; 65% (72/111) of patients were female, 87% (97/111) were white, and 49% (54/111) had brown irides. The mean age was approximately 40 years. Seventy-three eyes were treated with olopatadine, 75 with azelastine, and 74 with placebo. A single dose of 1 of the 3 study medications per eye was well tolerated by all subjects. Both treatments were significantly more effective than placebo at reducing itching postchallenge. Olopatadine was significantly more effective than azelastine in reducing itching at 3.5 minutes through 20 minutes postchallenge (average mean unit difference of -0.31; P < 0.05) in the CAC model.
Conclusion: In this population, olopatadine was significantly more effective than azelastine in the management of itching associated with allergic conjunctivitis in the CAC model.