A Comparative Preclinical Evaluation of a Novel Difluprednate 0.04% BID Ophthalmic Solution and Marketed 0.05% QID Ophthalmic Emulsion.

Purpose: The purpose of this study was to compare the efficacy, and ocular pharmacokinetics of a new 0.04% w/v bis in die means twice a day (BID) ophthalmic solution and marketed 0.05% w/v quater in die means four times a day (QID) ophthalmic emulsion of difluprednate in New Zealand white (NZW) rabbits. Methods: The preclinical proof of concept was established in paracentesis-induced acute inflammation, endotoxin-induced acute uveitis, and bovine serum albumin-induced chronic uveitis in NZW rabbit animal models. A comparison of clinical score, total cell count, and total protein was performed to determine efficacy. An ocular pharmacokinetic study was conducted to study the influence of the vehicle on the ocular absorption of the drug. Results: In both uveitis models, the new solution formulation and marketed emulsion formulation inhibited total clinical score, total cell count, PGE2, and total protein significantly more than the placebo and lipopolysaccharide (disease control) groups and were comparable. In an ocular pharmacokinetic study, the Cmax and AUC0-t of difluoroprednisolone 17-butyrate in humor were ∼2-fold higher after 14 days' instillation of new solution formulation (0.04% w/v, BID) compared with 14 days' instillation of marketed emulsion (0.05% w/v, QID). Conclusions: The study demonstrated that the efficacy of the solution formulation at a lower dose and reduced dosing regimen were comparable to that of the emulsion formulation. The reduction in strength and regimen may result in improved patient adherence and outcomes.