Plasma and Ocular Prednisolone Disposition after Oral Treatment in Cats

Abstract

Objective: To evaluate the plasma and aqueous humor disposition of prednisolone after oral administration in cats. Methods: Six cats were administered with a single oral dose of prednisolone (10 mg). Blood and aqueous humor samples were serially collected after drug administration. Prednisolone concentrations in plasma and aqueous humor were measured at 0.25, 0.5, 1.0, 1.5, 2.0, 3.0, 4.0 and 5.0 h after administration by a high-performance liquid chromatographic analytical method developed and validated for this purpose. Results: Mean±standard error (SE) of maximum plasma prednisolone concentration (300.8±67.3 ng/mL) was reached at 1 h post-administration. Prednisolone distributed to the aqueous humor reaching a mean peak concentration of 100.9±25.5 ng/mL at 1.25 h post-administration. The mean ± SE systemic and aqueous humor exposure (AUC) was 553.3±120.0 ng*h/mL and 378.8±64.9 ng*h/mL, respectively. A high AUCaqueous humor/AUCplasma ratio was observed (0.68±0.13). The mean half life time of elimination in plasma and aqueous humor was 0.87±0.16 h and 2.25±0.44 h, respectively. Clinical Significance: The observed high ratio between aqueous humor and plasma concentration indicates that extensive penetration of prednisolone to the anterior segment of the eye may occur. This is the first step that contributes to optimize the pharmacological therapeutics for the clinical treatment of uveitis.