INTRAVITREOUS DELIVERY OF DEXAMETHASONE SODIUM M-SULFOBENZOATE FROM POLY(DL-LACTIC ACID) IMPLANTS

Biodegradable intravitreal rod-shaped implants containing dexamethason e sodium m-sulfobenzoate (DMSB) were prepared from blends of poly(DL-l actic acid) (PLA) with number-average molecular weight 2000 (PLA2000) and 4000 (PLA4000). The effect of the fraction of PLA2000 on the relea se of DMSB from the implant was investigated after implantation in the vitreous body of rabbit eyes. After the initial burst, the drug was r eleased slowly from the blended PLA implants with a PLA2000 fraction o f below 30 wt% in normal eyes within a period of 28 d. For the implant s with a higher PLA2000 fraction of over 50 wt%, the drug was released following approximately first order kinetics. In the vitrectomized ey es, the release of DMSB from the PLA2000/PLA4000 (5/5) implant was 2.5 times more rapid than in normal eyes, and the clearance of drug was a lso appreciably accelerated as compared with that in normal eyes.