Intravitreal drug delivery by microspheres of biodegradable polymers

We evaluated the efficacy of microspheres of biodegradable polymers as a slow releasing drug delivery system in the vitreous body. Microspheres containing 5-FU were prepared with polymers of poly-(lactic acid) or copolymers of glycolic acid and lactic acid. The release of the drug was studied in vitro. Poly-(lactic acid) microspheres released 5-FU for 7 days. The intravitreal kinetics of the microspheres was studied in rabbits in vivo. The microspheres disappeared from the vitreous cavity of normal eyes by 48 +/- 5 days after injection. Disappearance was accelerated from the vitreous cavity of vitrectomized rabbits (14 +/- 2 days, p less than 10(-6)). No abnormality was found on electroretinographic or histological examinations after microspheres injection. These results suggested that microspheres of biodegradable polymers could be useful as a potential drug delivery system for sustained drug release in the vitreous body.