Epinastine Cream: A Novel Once-Daily Therapeutic Agent for Allergic Conjunctivitis

Purpose: To investigate the in vivo efficacy of epinastine cream in type I allergic models. Methods: The dose, timing, and antiallergic effect of epinastine cream on the conjunctiva were evaluated postapplication to the eyelid skin of guinea pigs with histamine- or ovalbumin-induced allergic conjunctivitis. Additionally, we assessed its antiallergic effects on the skin postapplication to the dorsal skin of guinea pigs with ovalbumin-induced passive cutaneous anaphylaxis. Efficacy was estimated by determining the amount of dye that leaked from conjunctival or dorsal skin tissue vessels as a measure of vascular permeability, scoring the severity of allergic symptoms, and observing the scratching behaviors using clinical parameters. Results: In the histamine-induced conjunctivitis model, epinastine cream strongly inhibited conjunctival vascular permeability in a dose-dependent manner. The inhibitory effect of 0.5% epinastine cream 24 h postapplication was significantly higher than that of 0.1% epinastine hydrochloride ophthalmic solution 8 h postadministration. Additionally, the 0.5% epinastine cream inhibited conjunctival vascular permeability 15 min postapplication, and the effect was sustained over 24 h. Furthermore, the 0.5% epinastine cream effectively suppressed clinical symptom scores and exhibited ameliorated scratching bouts in conjunctival allergic reactions in the experimental allergic conjunctivitis model. Additionally, it significantly inhibited vascular permeability in skin allergic reactions in the passive cutaneous anaphylaxis model. Conclusions: The results suggest that epinastine cream is a strong, long-lasting, and skin-penetrating inhibitor of type I allergic reactions. The 0.5% epinastine cream applied once daily could be a promising, potent, and long-acting therapeutic agent for allergic conjunctivitis.