Efficacy of N-acetyl aspartyl glutamic acid versus fluorometholone for treating allergic conjunctivitis in an environmental exposure chamber

Background Topical mast cell stabilizers were previously shown to treat the signs and symptoms of seasonal and perennial allergic conjunctivitis safely and effectively in active and placebo-controlled trials. However, mast cell stabilizers have not been compared to topical corticosteroids for efficacy. We tested the non-inferiority of a topical mast cell stabilizer, N-acetyl aspartyl glutamic acid (4.9%, NAAGA), compared to fluorometholone (0.1%, FM) during controlled exposures to the airborne birch pollen allergen, Bet v 1, in an environmental exposure chamber (EEC). Methods This randomized, cross-over, investigator-blinded study included 24 patients with a history of birch pollen allergic conjunctivitis. Patients were randomized to 5 days of treatment with NAAGA, then FM (n = 12) or FM, then NAAGA (n = 12). After each treatment, patients were exposed to a fixed airborne concentration of Bet v 1 in ALYATEC EEC. The primary endpoint was the amount of allergen required to trigger a conjunctival response (Abelson score >= 5). Groups were compared with a linear model for cross-over studies. Non-inferiority was assumed, when the lower bound of the risk ratio confidence interval (CI) was >0.5. Results At screening, the mean time-to-conjunctival response was 72.5 +/- 35.9 min. NAAGA and FM extended the response time to 114.8 +/- 55.0 and 116.6 +/- 51.5 min respectively. The mean amounts of allergen required to trigger a conjunctival response were 1.165 ng after NAAGA and 1.193 ng after FM treatment. The risk ratio for the conjunctival response was 0.977 (95% CI: 0.812; 1.174), which indicated non-inferiority. Adverse events occurred less frequently with NAAGA (29.2%) than with FM (58.3%). Conclusion In patients with allergic conjunctivitis to birch pollen, NAAGA was non-inferior to FM in exposures to airborne Bet v 1. The EEC was a good model for simulating real-life airborne allergen exposure and for demonstrating the efficacy and safety of eye drops for treating allergic conjunctivitis.