Abstract
Purpose:
To evaluate the 24-hour ocular distribution and concentrations of 14C-Iabeled low-concentration, modified bromfenac ophthalmic solution following topical instillation in New Zealand White rabbit eyes.
Methods:
Eighteen New Zealand white rabbits were randomly assigned to 6 treatment groups (3 animals per treatment group). A single dose of 50µL of the dosing solution was topically administered into the conjunctival sac of both eyes of each animal. Animals were euthanized and the aqueous humor was collected at 1 hour ± 5 minutes, 2 hours ± 15 minutes, 4 hours ± 15 minutes, 8 hours ± 15 minutes, 12 hours ± 15 minutes, or 24 hours ± 15 minutes following dosing. The iris/ciliary body, lens, vitreous, retina, choroid, sclera, conjunctiva, and cornea (target tissues) were also collected from each eye for analysis. Dosing solutions were analyzed to confirm radiochemical purity; radioactive concentration of the dosing solutions was calculated using liquid scintillation counting (LSC).
Results:
Radioactive residues of 14C-Iabeled bromfenac, expressed as mean parts per million [(ppm) µg/g] was seen in all target tissues of the eyes, with the highest concentrations found in the cornea, conjunctiva, and sclera. The concentrations in the tissues diminished to varying degrees over the 24 hour study period, with the exception of the lens, which increased insignificantly from the 1 hour time point. The levels detected in the lens and vitreous humor were low and close to background levels.
Conclusions:
Significant penetration and measurable amounts of 14C-labeled bromfenac were detected in most ocular target tissues over 24 hours, with highest levels in the cornea, conjunctiva, and sclera. The 14C-low concentration bromfenac residues in ocular tissues were similar to those previously reported with 0.09% 14C-bromfenac, the currently available concentration of bromfenac ophthalmic solution.
Keywords: 557 inflammation •
445 cataract •
637 pathology: experimental