Ocular bioavailability and tissue distribution of [14C]ketorolac tromethamine in rabbits

The ocular bioavailability of 0.5% [14C]ketorolac tromethamine administered topically (50 microL) to the eye was determined. The ocular bioavailability of ketorolac was 4% in anesthetized rabbits and was determined by comparing drug concentrations in the aqueous humor after topical application with those obtained after intracameral injection of an equivalent dose of 0.25 mg of ketorolac tromethamine per eye. Although ketorolac administered to the eye was completely absorbed systemically, concentrations of ketorolac (AUC) were, on the average, 13 times higher in the aqueous humor than in plasma after topical administration. In a separate ocular distribution study, peak concentrations of radioactivity were achieved in the ocular tissues and in plasma within 1 h post instillation. Concentrations of total radioactivity were highest in the cornea and sclera and lowest in the lens.