용매증발법에 의한 부피바카인 microsphere의 제조 및 평가 = Preparation and Evaluation of Bupivacaine Microspheres by a Solvent Evaporation Method

다국어 초록 (Multilingual Abstract)

Various bupivacaine-loaded microspheres were prepared from poly (d,l-lactide) (PLA) or poly (d,l-lactic-co-glycolide) (PLGA) by a solvent evaporation method for the sustained release of drug. PLA and PLGA microspheres were prepared by w/o/w and w/o/o multiple emulsion solvent evaporation, respectively. The effects of process conditions such as emulsification speed, emulsifier type, emulsifier concentration and internal/external phase ratio on the characteristics of microspheres were investigated. The prepared microspheres were characterized for their drug loading, size distribution, surface morphology and release kinetics. Drug loading efficiency was higher in the microspheres prepared by w/o/o multiple emulsion than that by w/o/w multiple emulsion mehtod, because the solubility of bupivacaine HCl was decreased in oil phase compared with water phase. The prepared microspheres had an average diameter between 1 and 2mcm in all conditions of two methods. In morphology studies the PLA microspheres showed an irregular shape and smooth surface, but PLGA microspheres had a spherical shape and smooth surface. The release pattern of the drug from microspheres was evaluated on the basis of the burst effect and the extent of the release after 24h. The in vitro release of bupivacaine HCl from microspheres showed a large initial burst release and 60-80% release within one day in all conditions of two methods. The extents of the burst release against PLA and PLGA microspheres were 30-50% and 50-80% within 20min, respectively. This burst release seems to be due to the smaller size of microspheres and the solubility of drug in water.