title: Formulation, characterization and in vitro evaluation of theophylline-loaded Eudragit RS 100 microspheres prepared by an emulsion-solvent diffusion/evaporation technique.
abstract: The aim was to prepare theophylline-loaded Eudragit RS 100 microsphere to achieve sustained release pattern with relatively high production yield. To this end, microspheres were prepared by oil/oil solvent evaporation method using an acetone-methanol mixture and liquid paraffin system containing aluminum tristearate. Drug release profiles were determined at pH 1.2 and 7.4. Morphology and solid state of microspheres were examined using SEM, DSC, X-ray powder diffraction (XRPD), and FT-IR. As the ratio of acetone/methanol increased during the preparation of microspheres the size of microsphere was reduced. The highest drug loading efficiency (87.21%) was obtained for the microsphere containing a high ratio of polymer to drug (6:1) and high volume of acetone. SEM studies showed that the microspheres are almost spherical with a few pores and cracks at surfaces. The FT-IR, XRPD and DSC results ruled out any chemical interaction between theophylline and Eudragit. The microspheres prepared with low ratio of polymer to drug (1:2) showed faster dissolution rate than those with high polymer to drug ratio. The ratio of polymer to drug and the volume of polymer solvent were found to be the key factors affecting the release profile which could lead to microspheres with desired release behavior.
authors: Drug Applied Research Center and Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.
authors: Mitra
authors: M
authors: Jelvehgari
authors: Jaleh
authors: J
authors: Barar
authors: Hadi
authors: H
authors: Valizadeh
authors: Sanam
authors: S
authors: Shadrou
authors: Ali
authors: A
authors: Nokhodchi
mesh_terms: D000096:Acetone / Q000737:chemistry; D000180:Acrylic Resins / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D003692:Delayed-Action Preparations; D004337:Drug Carriers / Q000737:chemistry*; D004655:Emulsions; D005079:Excipients / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D000432:Methanol / Q000737:chemistry; D008863:Microspheres; D009821:Oils / Q000737:chemistry; D010316:Particle Size; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013229:Stearic Acids / Q000737:chemistry; D013806:Theophylline / Q000008:administration & dosage* / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D000180:Acrylic Resins; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D004655:Emulsions; D005079:Excipients; D009821:Oils; D012997:Solvents; D013229:Stearic Acids; D000096:Acetone; C050528:Eudragit RS; C031183:stearic acid; D013806:Theophylline; D000432:Methanol