Abstract
Abstract: :
Purpose: To examine relevance of platelet activating factor (PAF) to allergic conjunctivitis and apafant, a potent PAF antagonist, for topical ocular anti-PAF activity in experimental conjunctivitis. Methods: In PAF-induced conjunctivitis models, PAF solution was topically applied to the eyes of guinea pigs. Apafant ophthalmic solution was instilled 15 and 5 min before the challenge. The efficacy was evaluated by determining Evans blue dye extravasation into the ocular tissues, itch-scratching response, and clinical symptoms such as redness and edema. In a passive conjunctival anaphylaxis model, allergic conjunctivitis was elicited by application of ovalbumin solution into the eyes of the guinea pigs that had been passively sensitized with anti-ovalbumin serum. The effect of apafant, which was administered 15 and 5 min before the challenge, was evaluated by determining Evans blue dye extravasation into the ocular tissues. Results: PAF, when applied topically to the eyes of guinea pigs, induction of conjunctival vascular leakage, itch-scratching response, and clinical symptoms such as redness and edema was observed. These symptoms observed in PAF-induced conjunctivitis were well correspondent to those observed in allergic conjunctivitis. Apafant inhibited the responses in a dose-related manner, and the inhibitory effects lasted for about 6 hours duration. In a passive conjunctival anaphylaxis model of guinea pigs, significant inhibition of the allergic response was observed following topical ocular administration of apafant. Conclusions: These results indicate that PAF plays a key role in the pathophysiology of allergic conjunctivitis and apafant is a promising candidate of new anti-allergic eyedrop.
Keywords: pharmacology • conjunctivitis • lipids