EFFICACY OF NEDOCROMIL SODIUM AND CROMOLYN SODIUM IN AN EXPERIMENTAL-MODEL OF OCULAR ALLERGY

Background: Because ocular allergic disorders are important in terms o f frequency and severity, there is a constant search for new topical a ntiallergic drugs. Nedocromil sodium has recently been introduced as a potential substitute for the mast cell stabilizer cromolyn sodium. Ob jective: We compared the efficacy of topical 2% nedocromil sodium to t hat of 2% cromolyn sodium in treatment of the early-phase reaction of an experimental model of allergic conjunctivitis. Methods: Guinea pigs were challenged topically with egg albumin 14 days after systemic imm unization. Fifteen minutes before, immediately prior to, and 15 minute s after topical challenge, the animals received either 2% nedocromil s odium or 2% cromolyn sodium topically in one eye and phosphate buffere d saline (PBS) in the other eye. Antigen-induced increase in vascular permeability was measured by the extravasation of intravenously inject ed Evans blue dye. Animals that were immunized and topically challenge d but did not receive Evans blue were used for histologic studies. Res ults: Evans blue extravasation from ocular tissues significantly decre ased in drug-treated eyes compared with PBS-treated eyes (P < .01). Fu rther, the cellular infiltrate (mast cells, eosinophils, and neutrophi ls) in the substantia propria of the conjunctiva was markedly reduced in the drug-treated eyes. No significant difference was observed betwe en the nedocromil sodium- or cromolyn sodium-treated eyes. Conclusions : Topical 2% nedocromil sodium reduces the early-phase reaction of the allergic response as effectively as 2% sodium cromoglycate in a guine a pig model of ocular anaphylaxis.