title: Polymeric nanoparticles - Influence of the glass transition temperature on drug release.
abstract: The physico-chemical characterisation of nanoparticles is often lacking the determination of the glass transition temperature, a well-known parameter for the pure polymer carrier. In the present study the influence of water on the glass transition temperature of poly (DL-lactic-co-glycolic acid) nanoparticles was assessed. In addition, flurbiprofen and mTHPP as model drugs were incorporated in poly (DL-lactic-co-glycolic acid), poly (DL-lactic acid), and poly (L-lactic acid) nanoparticles. For flurbiprofen-loaded nanoparticles a decrease in the glass transition temperature was observed while mTHPP exerted no influence on this parameter. Based on this observation, the release behaviour of the drug-loaded nanoparticles was investigated at different temperatures. For all preparations an initial burst release was measured that could be attributed to the drug adsorbed to the large nanoparticle surface. At temperatures above the glass transition temperature an instant drug release of the nanoparticles was observed, while at lower temperatures less drug was released. It could be shown that the glass transition temperature of drug loaded nanoparticles in suspension more than the corresponding temperature of the pure polymer is the pivotal parameter when characterising a nanostructured drug delivery system.
authors.affiliation: Institute of Pharmaceutical Technology and Biopharmacy, University of Muenster, Corrensstraße 48, 48149 Münster, Germany.
authors.forename: Svenja
authors.initials: S
authors.lastname: Lappe
authors.affiliation: Institute of Pharmaceutical Technology and Biopharmacy, University of Muenster, Corrensstraße 48, 48149 Münster, Germany.
authors.forename: Dennis
authors.initials: D
authors.lastname: Mulac
authors.affiliation: Institute of Pharmaceutical Technology and Biopharmacy, University of Muenster, Corrensstraße 48, 48149 Münster, Germany. Electronic address: k.langer@wwu.de.
authors.forename: Klaus
authors.initials: K
authors.lastname: Langer
mesh_terms: D065546:Drug Liberation; D005480:Flurbiprofen / Q000737:chemistry / Q000493:pharmacokinetics*; D005898:Glass / Q000737:chemistry; D019344:Lactic Acid / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011091:Polyesters / Q000737:chemistry*; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011166:Porphyrins / Q000737:chemistry / Q000493:pharmacokinetics*; D012995:Solubility; D013696:Temperature; D044366:Transition Temperature
chemical_list: D011091:Polyesters; D011166:Porphyrins; C437342:tetra(3-hydroxyphenyl)porphine; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; C033616:poly(lactide); D005480:Flurbiprofen
keywords: Differential scanning calorimetry; Drug delivery system; Poly (DL-lactic-co-glycolic acid); Poly (lactic acid); Release profile