Comparison of the clinical efficacy and comfort of olopatadine hydrochloride 0.1% ophthalmic solution and nedocromil sodium 2% ophthalmic solution inthe human conjunctival allergen challenge model

Background: Mast cell stabilizers, such as the ocular antiallergic agent ne docromil sodium 2% ophthalmic solution, are not rapid acting and often requ ire a loading period of greater than or equal to2 weeks for maximal efficac y. Olopatadine hydrochloride 0.1% ophthalmic solution is a member of a new class of topical antiallergic agents that have combined antihistaminic and mast cell-stabilizing properties. Objective: The purpose of this study was to compare the clinical efficacy a nd comfort of olopatadine with those of nedocromil in the conjunctival alle rgen challenge model. Methods: This was a single-center 3-visit randomized, double-masked, contra laterally controlled study. Seventy-five subjects with a history of allergi c conjunctivitis were screened, and the 52 who responded to conjunctival al lergen challenge at visits 1 and 2 were randomized by eye to receive olopat adine, nedocromil, or placebo (a "natural tears" lubricant eye drop). Becau se nedocromil may require a 2-week loading period for maximal efficacy, the eyes assigned to that agent received nedocromil for 14 days (between visit s 2 and 3), whereas the eyes assigned to olopatadine or placebo received pl acebo during this period. Throughout the loading phase, subjects instilled 1 drop of the assigned masked medication in each eye twice daily. At the as sessment visit (visit 3), subjects received 1 drop of masked olopatadine, n edocromil, or placebo in each eye and were asked to rate the comfort of eac h drop on a scale from 0 to 8. Fifteen minutes after instillation of medica tion subjects were challenged with the allergen concentration that had elic ited a positive conjunctival allergic response at the previous visits. Subj ects then scored their itching on a scale from 0 to 4 at 3, 5, and 10 minut es after challenge. Mean itching scores for all eyes were compared by treat ment. Paired t tests were performed on the mean itching and ocular comfort scores at each time point. At the end of the study, subjects were asked whi ch treatment they preferred in terms of comfort and efficacy. Results: Forty-nine subjects completed the study. Forty eyes received olopa tadine, 36 received nedocromil, and 22 received placebo. Olopatadine was cl inically and statistically superior to nedocromil at reducing itching in th e conjunctival allergen challenge model (mean unit difference: -1.60 at 3 m inutes, -1.68 at 5 minutes, -1.19 at 10 minutes; P < 0.001). One drop of ol opatadine was more efficacious than 29 drops of nedocromil. Olopatadine-tre ated eyes were rated as being significantly more comfortable than nedocromi l-treated eyes (0.73 vs 1.55; P = 0.034). Of the 14 subjects treated with o lopatadine and nedocromil who stated a preference, 10 (71%) were more satis fied with olopatadine than with nedocromil. Conclusion: In the conjunctival allergen challenge model, olopatadine was m ore efficacious and comfortable than nedocromil in reducing the itching ass ociated with allergic conjunctivitis.