title: Bupivacaine-loaded biodegradable poly(lactic-co-glycolic) acid microspheres I. Optimization of the drug incorporation into the polymer matrix and modelling of drug release.
abstract: Bupivacaine has been encapsulated by solvent evaporation method based on O/W emulsion, using poly(DL-lactic-co-glycolic) acid (PLGA) 50:50. The particle size can be controlled by changing stirring rate and polymer concentration. The encapsulation efficiency was affected by polymer concentration and burst effect of bupivacaine released from particles was affected by drug/polymer mass ratio. Orthogonal design was used to optimize the formulation according to drug content, encapsulation efficiency and burst effect. The dissolution profile and release model were evaluated with two different bupivacaine microspheres (bupi-MS) groups including low drug loading (6.41%) and high drug loading (28.92%). It was observed that drug release was affected by drug loading especially the amount of drug crystal attached on surface of bupi-MS. The drug release profile of low drug loaded bupi-MS agreed with Higuchi equation and that of high drug loaded bupi-MS agreed with first order equation.
authors.affiliation: Department of Pharmaceutics, School of Pharmacy, Second Military Medical University, 325 Guohe Road, Shanghai 200433, PR China.
authors.forename: He
authors.initials: H
authors.lastname: Zhang
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.forename: Guoqing
authors.initials: G
authors.lastname: Zhang
authors.forename: Shen
authors.initials: S
authors.lastname: Gao
authors.forename: Duxin
authors.initials: D
authors.lastname: Sun
authors.forename: Yanqiang
authors.initials: Y
authors.lastname: Zhong
mesh_terms: D000779:Anesthetics, Local / Q000737:chemistry*; D002045:Bupivacaine / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical / Q000379:methods; D003692:Delayed-Action Preparations; D004337:Drug Carriers / Q000737:chemistry; D004655:Emulsions; D019344:Lactic Acid / Q000737:chemistry*; D008863:Microspheres; D010316:Particle Size; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D012995:Solubility
chemical_list: D000779:Anesthetics, Local; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D004655:Emulsions; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D002045:Bupivacaine