IMPROVING PROTEIN DELIVERY FROM MICROPARTICLES USING BLENDS OF POLY(DL LACTIDE CO-GLYCOLIDE) AND POLY(ETHYLENE OXIDE)-POLY(PROPYLENE OXIDE)COPOLYMERS

Purpose. Microparticles containing ovalbumin as a model for protein dr ags were formulated from blends of poly(DL lactide-co-glycolide) and p oly(ethylene oxide)-poly(propylene oxide) copolymers (Pluronic). The o bjectives were to achieve uniform release characteristics and improved protein delivery capacity. Methods. The water- in oil -in oil emulsio n/solvent extraction technique was used for microparticle production. Results. A protein loading level of over 40% (w/w) was attained in mic roparticles having a mean diameter of approximately 5 mu m. Linear pro tein release profiles over 25 days in vitro were exhibited by certain blend formulations incorporating hydrophilic Pluronic F127. The releas e profile tended to plateau after IO days when the more hydrophobic Pl uronic L121 copolymer was used to prepare microparticles. A delivery c apacity of 3 mu g OVP/mg particles/ day was achieved by formulation of microparticles using a 1:2 blend of PLG:Pluronic Flu. Conclusions. Th e w/o/o formulation approach in combination with PLG:Pluronic blends s hows potential for improving the delivery of therapeutic proteins and peptides from microparticulate systems. Novel vaccine formulations are also feasible by incorporation of Pluronic L121 in the microparticles as a co-adjuvant.