Allergic Conjunctivitis: A Survey of New Antihistamines

ABSTRACT The objective of this study was to determine the therapeutic value of a wide variety of H1 antihistamines for potential ophthalmic use by performing ocular toxicity and efficacy tests in rabbits and humans. Fourteen antihistamines were formulated into ophthalmic preparations and were screened in the rabbit model; of these, thirteen were preliminarily evaluated for toxicity and efficacy in humans. Based on comfort and efficacy, four (pheniramine, chlorpheniramine, dexbrompheniramine and pyrilamine) were selected for more extensive dose response and efficacy testing. 0.3% chlorpheniramine, dexbrompheniramine, pyrilamine and pheniramine significantly reduced histamine-induced itching (p≤0.01 for each drug) and conjunctival injection (p≤0.02 for each drug), when compared to contralateral eyes receiving PBS. When compared to 0.3% pheniramine in the fellow eye (mean difference score=0.79±0.21), 0.3% chlorpheniramine (1.5±0.22; p=0.04) and 0.3% dexbrompheniramine (1.71±0.18;p=0.01) were superior in decr...