An Evaluation of Onset and Duration of Action of Patanol ® (Olopatadine Hydrochloride Ophthalmic Solution 0.1%) Compared to Claritin ® (Loratadine 10 mg) Tablets in Acute Allergic Conjunctivitis in the Conjunctival Allergen Challenge Model

. Purpose: To compare the clinical efficacy of Patanol ® (olopatadine hydrochloride ophthalmic solution 0.1%) to Claritin ® (loratadine 10 mg) tablets, in the conjunctival allergen challenge model. Methods: This was a randomized, double‐masked, single center, contralateral controlled, antigen challenge model study. The concentration of allergen that elicited a positive response was determined at Visits 1 and 2 (itching ≥2 and redness ≥2 OU). At Visit 3, 29 subjects were randomized into two groups. Fifteen subjects received Claritin ® tablet and Patanol ® ophthalmic solution 0.1% in one eye and placebo in the contralateral eye. Fourteen subjects received placebo tablet and Patanol ® in one eye and placebo in the contralateral eye. One hour after drug administration, subjects were challenged with the antigen that elicited a positive response. At 3, 7, and 10 minutes, itching was subjectively evaluated. At Visit 4, the same procedure was followed as in Visit 3, but antigen challenge occurred 8 hours after drug instillation. Results: Results were analyzed by eye. Eyes treated with Patanol ® (concomitant with placebo tablet) had significantly lower ocular itching scores when compared to eyes treated with placebo (concomitant with Claritin ® ) at 3, 7 and 10 minutes in the onset of action evaluation (p<0.05). Eyes treated with Patanol ® (concomitant with placebo tablet) had significantly lower ocular itching scores at 7 minutes and there was a statistical trend (0.05<p<0.1) at 10 minutes in duration of action evaluation. Conclusions: Patanol ® therapy was significantly more efficacious than Claritin ® in reducing ocular itching related to allergic conjunctivitis.