24-Hour Evaluation of the Ocular Distribution of 14C-Labeled Bromfenac Following Topical Instillation into the Eyes of New Zealand White Rabbits

Abstract

The aim of this study was to determine the distribution and concentrations of bromfenac ophthalmic solution in ocular tissues following topical instillation in New Zealand White (NZW) rabbits. Two animal studies were conducted. A single 50-muL (14)C-bromfenac ophthalmic solution (20-25 muCi or 0.09%) was administered into the right eyes of 14-18 randomly assigned NZW rabbits. At various time points, ocular tissues were collected and analyzed for (14)C-bromfenac contents. Ocular tissues were combusted and the amount of radioactivity was determined by liquid scintillation counting (LSC). Aqueous-humor samples were directly transferred to LSC vials. Peak concentrations of (14)C-bromfenac were observed in the aqueous humor and most ocular tissues at or before 2-hours. The highest concentrations were in the cornea, conjunctiva, and sclera. Similar amounts were detected in the aqueous humor, iris-ciliary body, choroid, and, to a slightly lesser degree, in the retina. Measurable amounts of bromfenac were detected in all samples at the 24-hours time point (> or =0.001 mug equivalent/g). Significant penetration and measurable amounts of (14)C-bromfenac were detected in all ocular tissues over 24 h, including the sclera, choroid, and retina. These results strongly suggest the utility of bromfenac ophthalmic solution 0.09% in treating inflammation of both the anterior and posterior ocular segments.