title: [Influence of water-soluble additives on drug release kinetics from biodegradable poly(lactic-co-glycolic acid) matrix].
abstract: OBJECTIVE
  To evaluate the effects of an array of additives on drug release from double-layered poly(lactic-co-glycolic acid) (PLGA) matrices.
  
  
  METHODS
  Additives differing in molecular size, hydrophilicity and steric configuration were selected for this study. An anti-proliferative 2-aminochromone, U-86983 (U-86, Pharmacia and Upjohn), was used as a model agent because of our interest in investigating local drug delivery systems for the inhibition of restenosis.
  
  
  RESULTS
  In vitro release of U-86 PLGA matrices without additive showed a typical biphasic release kinetics, i.e. a slow diffusion release (Phase I) followed by a fast erosion-mediated release (Phase II). The water-soluble additives in PLGA matrices changed the biphasic release pattern to a near monophasic profile by increasing the release of the Phase I. Increasing the ratio of additives to PLGA in matrices caused a significant increase in U-86 release rates. A high molecular weight water-soluble additive, Pluronic F127, resulted in a matrix showing perfect zero-order release kinetics. The morphologic evaluation of matrices using scanning electron microscopy indicated that the water-soluble additives were leachable and thus generated a highly porous structure in the matrices. Conclusion Water-solubility, molecular size and steric configuration of additives are the important determinants in generating various types of pore structures in polymer matrix which in turn affect the release mechanism and release kinetics.
authors.affiliation: The Institute of Biomedical Engineering, Chinese Academy of Medical Sciences, Tianjin 300192, China. lpsong@eyou.com
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Song
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.forename: Hai
authors.initials: H
authors.lastname: Wang
authors.forename: Hong-Fan
authors.initials: HF
authors.lastname: Sun
authors.forename: Li-Na
authors.initials: LN
authors.lastname: Tang
authors.forename: Li
authors.initials: L
authors.lastname: Wu
authors.forename: Jin
authors.initials: J
authors.lastname: Chang
authors.forename: Cun-Xian
authors.initials: CX
authors.lastname: Song
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D002867:Chromones / Q000008:administration & dosage* / Q000737:chemistry; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D016503:Drug Delivery Systems; D005079:Excipients / Q000737:chemistry; D019344:Lactic Acid / Q000737:chemistry*; D008970:Molecular Weight; D009025:Morpholines / Q000008:administration & dosage* / Q000737:chemistry; D010599:Pharmacokinetics; D020442:Poloxamer / Q000737:chemistry*; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry*; D013644:Tartrates / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D002867:Chromones; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D005079:Excipients; D009025:Morpholines; D011108:Polymers; D013644:Tartrates; C118403:tartaric acid dimethyl ether; D020442:Poloxamer; C090113:U 86983; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid