title: Kinetics of drug release from a hyaluronan-steroid conjugate investigated by NMR spectroscopy.
abstract: The methylprednisolone steroid ester of hyaluronan was hydrolyzed under physiological conditions in vitro, and the kinetics of drug release was investigated by NMR spectroscopy. Transverse relaxation times are correlated with the molecular rotational freedom, which undergoes large changes for methylprednisolone when released. Multi-exponential decays were observed, which together with the corresponding population gave valuable insights into the conformational changes that occur in the biopolymer during hydrolysis. The biomaterial exists in aqueous solution in two conformations, 'collapsed' and 'water-exposed', in equilibrium. Under physiological conditions, the methylprednisolone is completely released within 48 h. Transverse relaxation times proved to be an appropriate tool for monitoring the drug release in vitro.
authors.affiliation: Agricultural Research Council, Research Centre for Soil-Plant Systems, Instrumental Center of Tor Mancina, S. P. Pascolarese-Strada della Neve Km 1, 00015 Monterotondo, Rome, Italy. anna.taglienti@entecra.it
authors.forename: Anna
authors.initials: A
authors.lastname: Taglienti
authors.forename: Paolo
authors.initials: P
authors.lastname: Sequi
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Valentini
mesh_terms: D006820:Hyaluronic Acid / Q000737:chemistry*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008775:Methylprednisolone / Q000737:chemistry*; D015394:Molecular Structure; D013256:Steroids / Q000737:chemistry*
chemical_list: D013256:Steroids; D006820:Hyaluronic Acid; D008775:Methylprednisolone