Effects of Nonsteroidal Anti-Inflammatory Drugs on Experimental Allergic Conjunctivitis in Guinea Pigs

Abstract

The effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on experimental allergic conjunctivitis, induced by ocular challenge with antigen in actively sensitized guinea pigs, were investigated. NSAIDs reduced the increase in prostaglandin D₂ (PGD₂) and E₂ (PGE₂) in the ocular lavage fluid. The inhibition of NSAIDs to these increases was approximately 90%–95%. NSAIDs also lowered itch-scratch response (ISR) to approximately one-third to one-half of the vehicle-treated group. However, these drugs scarcely affected plasma exudation in the conjunctiva. Ketotifen, an H₁ histamine receptor antagonist, inhibited both pathophysiological changes (inhibition: 70%–80%). However, this drug was less efficacious than NSAIDs in reducing PGD₂ and PGE₂ levels. Moreover, topical administration of histamine induced ISR and plasma exudation; in contrast, PGD₂ induced ISR exclusively. These results suggest that a part of antigen-induced ISR may be attributable to PGs. However, PGs may not play a key role in plasma exudation; other mediators such as histamine may be involved.