Evaluation of olopatadine, a new ophthalmic antiallergic agent with dual activity, using the conjunctival allergen challenge model

Background: An ophthalmic antiallergic agent with selective H-1 antihistaminic and mast cell stabilizing properties has been developed. Objectives: To evaluate efficacy and safety, determine optimal concentration, and demonstrate onset and duration of action of this new drug, olopatadine. Methods: This was a placebo-controlled, randomized, double-masked, parallel-group, single-center study with five outpatient visits at least 7 days apart. Ninety-eight healthy, allergy-positive, subjects with a recent history of active allergic conjunctivitis not receiving current treatment participated. Conjunctival allergen challenge (CAC) tests were per-formed on visits 1 and 2 to identify an allergen and concentration that consistently elicited signs and symptoms of allergic conjunctivitis. On visits 3, 4, and 5, CAC was performed 27 minutes, 8 hours, and 6 hours. respectively, after instillation of one drop of olopatadine (0.01%, 0.05%, 0.1%, or 0.15%) in one eye and placebo in the other. Both eyes were scored for the intensity of itching and redness at 3, 10, and 70 minutes after the CAC. Results: All four concentrations of olopatadine were clinically and statistically superior to placebo in preventing ocular itching at all evaluations and preventing redness at most evaluations from immediately and 8 hours after drug administration. No drug-related adverse events were reported. The 0.1% concentration was found to be most effective. Conclusions: The results indicate that olopatadine ophthalmic solution is safe and effective in the treatment of allergic conjunctivitis, with the 0.1% concentration of olopatadine being optimal. The rapid onset and at least 8 hour duration of action of olopatadine indicates that the drug can be used twice daily.