title: Controlled release from bioerodible polymers: effect of drug type and polymer composition.
abstract: The effect of the chemical nature of the drug on matrix degradation and drug release behavior of degradable polymers was studied, using lidocaine as a model drug in base and salt forms. We show in this study that the drug in the base form has a substantial effect on the release characteristics, through an accelerating effect on matrix degradation. Study of drug release from PdlLGA shows that lidocaine salt follows a three-phase release pattern, in contrast to the biphasic release of the lidobase. However, PlLA shows a different drug release pattern, with only a single diffusion phase exhibited for both lidobase and lidosalt. We also demonstrate that the crystallinity of matrix plays an important role on drug release profiles: a crystalline matrix (PlLA IV=2.04) releases the drug at a much slower rate compared to its amorphous counterpart of similar molecular weight (PdlLA IV=2.4). The details of the study of different factors influencing the drug release may have important implications for the control of delivery of potent drugs in various therapeutic windows.
authors.affiliation: School of Materials Engineering, N4.1-1-30, Nanyang Technological University, Nanyang Avenue, Singapore 639798, Singapore.
authors.forename: Alexis
authors.initials: A
authors.lastname: Frank
authors.forename: Santosh Kumar
authors.initials: SK
authors.lastname: Rath
authors.forename: Subbu S
authors.initials: SS
authors.lastname: Venkatraman
mesh_terms: D000465:Algorithms; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D002626:Chemistry, Pharmaceutical; D002850:Chromatography, Gel; D003692:Delayed-Action Preparations / Q000737:chemistry*; D005079:Excipients / Q000737:chemistry*; D007700:Kinetics; D019344:Lactic Acid; D008012:Lidocaine / Q000008:administration & dosage / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D011100:Polyglycolic Acid; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry*; D012995:Solubility; D014867:Water / Q000737:chemistry
chemical_list: D000779:Anesthetics, Local; D003692:Delayed-Action Preparations; D005079:Excipients; D011108:Polymers; D014867:Water; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D008012:Lidocaine