Abstract
Abstract: :
Purpose: We investigated the ocular and periocular distribution of topical nipradilol, and the penetration route of nipradilol to the posterior periocular tissues in rabbits. Methods: Male albino rabbits were used. In the ocular and periocular distribution study, [14C]nipradilol (1%, 100 µL) was instilled topically on one eye. In the penetration route study, [14C]nipradilol was injected into anterior chamber (0.1%, 100 µL) and Tenon's capsule (0.1%, 10 µL) on one eye. Distribution patterns of radioactivity at 15 and 60 minutes after applications were evaluated by whole-head autoradiography. Results: In the topical application study, equivalent nipradilol concentration in the periocular tissue around the optic nerve insertion was higher on the ipsilateral side than the contralateral side (187.8 ± 41.4 ng/g and 105.0 ± 35.6 ng/g, p<0.01). Radioactivity was higher in the periocular tissue behind the equator than around the optic nerve insertion on the ipsilateral side (p<0.01), but not on the contralateral side. The equivalent nipradilol concentration in the ipsilateral posterior retina-choroid was 2538.6 ± 1141.1 ng/g, which was significantly higher than that on the contralateral control side (108.1 ± 23.0 ng/g, p<0.01). In anterior chamber injection study, radioactivity was observed in the anterior part of eye but not in the posterior retina-choroid and the posterior periocular tissues around the insertion in the optic nerve. On the contrary, radioactivity was observed clearly in the posterior retina-choroid and the posterior periocular tissues around the insertion in the optic nerve by Tenon's capsule injection. Conclusions: These results indicated that nipradilol reached to the posterior periocular tissue and retina-choroid by topical application, and penetrates locally into those tissues via the periocular route on the ipsilateral side.
Keywords: pharmacology • drug toxicity/drug effects • animal model