title: Properties of theophylline tablets dry powder coated with Eudragit E PO and Eudragit L 100-55.
abstract: The aim of the present study was to investigate the influence of Eudragit E PO on the drug release mechanism of Eudragit L 100-55 film coatings applied to theophylline tablets by a dry powder coating technique. The process was entirely liquid-free. Calculation of the Flory-Huggins interaction parameter based on solubility parameters suggested immiscibility of the two copolymers. MDSC thermograms were characterized by two glass transitions for the investigated Eudragit E PO/Eudragit L 100-55 ratios and confirmed incomplete miscibility of the copolymers at processing conditions. FT-IR analysis was employed to study binding interactions of the polymers. Due to the higher affinity of the plasticizer, triethyl citrate, for Eudragit E PO compared to Eudragit L 100-55, redistribution of the plasticizer was observed during the curing phase of the process. Plasticizer migration also affected the initial phase of drug release from powder-coated theophylline tablets that were stored for four weeks. Drug release from powder-coated tablets was dependent on the polymer blend ratio, coating thickness, and the pH of the dissolution medium. A broad range of pH dependent theophylline release profiles were obtained as a function of the polymer blend ratio. The particle size of the coating powder influenced the microstructure of the film coating.
authors.affiliation: College of Pharmacy, The University of Texas at Austin, Austin, 78712, USA. dsauer@alumni.utexas.net
authors.forename: Dorothea
authors.initials: D
authors.lastname: Sauer
authors.forename: James
authors.initials: J
authors.lastname: McGinity
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000465:Algorithms; D001682:Biological Availability; D002152:Calorimetry, Differential Scanning; D004355:Drug Stability; D006813:Humidity; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D010592:Pharmaceutic Aids / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry*; D011208:Powders / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013608:Tablets, Enteric-Coated; D013627:Talc / Q000737:chemistry; D013696:Temperature; D013806:Theophylline / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D044366:Transition Temperature
chemical_list: D000180:Acrylic Resins; C446821:Eudragit L100-55; D010592:Pharmaceutic Aids; D011109:Polymethacrylic Acids; D011208:Powders; D013608:Tablets, Enteric-Coated; D013627:Talc; D011092:Polyethylene Glycols; C518398:Eudragit E PO; D013806:Theophylline