title: Structure formation in injectable poly(lactide-co-glycolide) depots.
abstract: Solutions of low-molecular-weight poly(lactide-co-glycolide) (PLGA) in organic solvents have been investigated as novel injectable drug depots for drug delivery over periods of weeks to months. In this paper, we investigated the structure formation in a PLGA/benzyl benzoate system, using controlled stress rheometry, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). GPC analysis demonstrated a decrease in molecular weight as a function of time and temperature, indicating degradation. Rheological experiments showed that the flow properties of PLGA/benzyl benzoate solutions were affected by a combination of degradation and gelation; the latter was also detected by an endotherm in DSC and by three-dimensional structure formation studies by rheology. Extent of degradation and gelation of PLGA were shown to depend on the solvent.
authors.affiliation: School of Materials Engineering, Nanyang Technological University, N4.1-1-30 Nanyang Avenue, 639798 Singapore.
authors.forename: Liwei
authors.initials: L
authors.lastname: Wang
authors.forename: Lothar
authors.initials: L
authors.lastname: Kleiner
authors.forename: Subbu
authors.initials: S
authors.lastname: Venkatraman
mesh_terms: D001565:Benzoates / Q000737:chemistry; D002152:Calorimetry, Differential Scanning; D002626:Chemistry, Pharmaceutical; D002850:Chromatography, Gel; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D004339:Drug Compounding; D004355:Drug Stability; D004356:Drug Storage; D007267:Injections; D019344:Lactic Acid / Q000008:administration & dosage / Q000737:chemistry*; D008787:Metoclopramide / Q000737:chemistry; D011100:Polyglycolic Acid / Q000008:administration & dosage / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000008:administration & dosage / Q000737:chemistry*; D011760:Pyrrolidinones / Q000737:chemistry; D012212:Rheology; D012997:Solvents; D013329:Structure-Activity Relationship; D013696:Temperature; D013997:Time Factors
chemical_list: D001565:Benzoates; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D011108:Polymers; D011760:Pyrrolidinones; D012997:Solvents; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C038678:N-methylpyrrolidone; D008787:Metoclopramide; C006723:benzyl benzoate