Comparative Ocular Pharmacokinetics of Dexamethasone Implants in Rabbits

Dexamethasone eye implant has been used to treat macular edema and non-infectious uveitis. To date, its ocular pharmacokinetics are not fully characterized, and the development of generic preparations is in progress, as the patent of the original brand expires soon. Therefore, this work was designed to 1) determine the time course of vitreous dexamethasone concentrations following intravitreal implantation in rabbits and 2) explore the alternative use of NDF-SI01 from a pharmacokinetic point of view compared to Ozurdex^®, which is currentlyused in the market. Ozurdex^® and NDF-SI01 were implanted into the right and left eyes of the rabbit, respectively. A serial vitreous collection was performed to minimize the sacrifice of animals, and dexamethasone concentrations were measured by HP LC-MS/MS. After implantation, dexamethasone concentration reaches the maximum concentration (3.1 μg/mL) in 19.5 days and decreases with a half-life of 40.3 h. AUC and clearance are 683.9 μg·h/mL and 1.29 mL/h, respectively. There is no significant difference in pharmacokinetic parameters between NDF-SI01 and Ozurdex^®. The overall patterns of the cumulative release of both implants are similar. NDF-SI01 could alternate Ozurdex^® in clinics based on the in vivo comparative pharmacokinetic study and in vitro dissolution test.