Pemirolast potassium 0.1% ophthalmic solution is an effective treatment for allergic conjunctivitis: a pooled analysis of two prospective, randomized, double-masked, placebo-controlled, phase III studies.

Patients with allergic conjunctivitis may experience several debilitating symptoms, particularly ocular itching. The objective of this study was to evaluate the efficacy and safety of pemirolast potassium 0.1% ophthalmic solution (Alamast trade mark ), a novel mast-cell stabilizer, for preventing ocular manifestations of seasonal allergic conjunctivitis. A pooled analysis was performed of data derived from 2 prospective, randomized, double-masked, placebo-controlled, multicenter phase III clinical trials of pemirolast potassium 0.1% in patients with a history of allergic conjunctivitis. Patients having a positive bilateral response to conjunctival allergen challenge (CAC) with ragweed antigen (N = 274) were randomized to receive pemirolast potassium 0.1% or placebo QID, beginning approximately 1-2 weeks before the onset of ragweed season and continuing until after the first killing frost (12-17 weeks duration). Patients recorded their daily evaluations of ocular itching in a diary. After the allergy season, patients underwent a second CAC. Evaluable patients (n = 265) recorded a total of 21,491 patient-days of ocular itching data during allergy season. In every 7-day or 14-day period, patients treated with pemirolast potassium 0.1% reported more days without any ocular itching compared with patients receiving placebo. Differences favoring pemirolast potassium 0.1% were statistically significant in 63% (10/16) of all 7-day periods (p < or = 0.046) and 88% (7/8) of all 14-day periods (p < or = 0.016). After the allergy season, pemirolast potassium 0.1% was significantly superior to placebo in relieving CAC-induced ocular itching, with relief occurring as early as 3 minutes after allergen challenge (p < or = 0.034). Pemirolast potassium 0.1% was well tolerated and had a safety profile similar to that of placebo. In conclusion, pemirolast potassium 0.1% is effective and safe in preventing ocular itching in patients with allergic conjunctivitis during allergy season.