Pharmacokinetics of Terbinafine in the Rabbit Ocular Tissues after Topical Administration

Objective: To determine the distribution of terbinafine in the cornea and aqueous humor after topical administration. Methods: A corn oil ointment of terbinafine 0.2% (resolved in sterile corn oil) was applied to the conjunctival sac of albino rabbits twice (with a 5-min interval). The concentration of terbinafine was determined with high-performance liquid chromatography (HPLC) 5, 15, 30, 60, 120 and 240 min after administration of terbinafine. Results: After topical administration, the concentration of terbinafine increased gradually, reached a peak (1.39 µg/ml at 30 min in the cornea and 82.9 ng/ml at 30 min in aqueous humor, respectively) and then decreased. The concentration was 0.18 µg/g at 240 min in the cornea, but terbinafine could not be tested at 120 min in aqueous humor. Conclusions: Topical ophthalmic terbinafine 0.2% could penetrate into the cornea and aqueous humor at concentrations adequate for inhibition of fungus.