title: Combination of time-dependent and pH-dependent polymethacrylates as a single coating formulation for colonic delivery of indomethacin pellets.
abstract: The objective of this study was to evaluate the combination of pH-dependent and time-dependent polymers as a single coating for design of colon delivery system of indomethacin pellets. Eudragit S100 and Eudragit L100 were used as pH-dependent polymers and Eudragit RS was used as a time-dependent polymer. A statistical full factorial design was used in order to optimize formulations. Factors studied in design were percent of Eudragit RS in combination with Eudragit S and L and coating level. Dissolution studies of pellets in the media with different pH (1.2, 6.5, 6.8 and 7.2) showed that drug release in colon could be controlled by addition of Eudragit RS to the pH-dependent polymers. The lag time prior to drug release was highly affected by coating level. With combination of two factors, i.e. the percent of Eudragit RS and coating level, the optimum formulation was found to be the one containing 20% Eudragit RS, 64% Eudragit S and 16% Eudragit L, and a coating level of 10%. This formulation was reproduced and tested in continuous condition of dissolution, and also separately at pH 7.5. The results of in vitro experiments indicate that the proposed combined time-dependent and pH-dependent polymethacrylate polymer coating may provide a colonic delivery system for indomethacin.
authors.affiliation: School of Pharmacy and Pharmaceutical Research Centre, Vakilabad Blvd., PO Box 91775-1365, Mashhad University of Medical Science, Mashhad, Iran.
authors.forename: A
authors.initials: A
authors.lastname: Akhgari
authors.forename: F
authors.initials: F
authors.lastname: Sadeghi
authors.forename: H Afrasiabi
authors.initials: HA
authors.lastname: Garekani
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D000704:Analysis of Variance; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry* / Q000378:metabolism; D002626:Chemistry, Pharmaceutical; D003106:Colon / Q000378:metabolism*; D005069:Evaluation Studies as Topic; D006863:Hydrogen-Ion Concentration; D007213:Indomethacin / Q000737:chemistry* / Q000378:metabolism; D007408:Intestinal Absorption; D015233:Models, Statistical; D011109:Polymethacrylic Acids / Q000737:chemistry*; D012044:Regression Analysis; D012995:Solubility; D013608:Tablets, Enteric-Coated; D013678:Technology, Pharmaceutical; D013997:Time Factors
chemical_list: D000180:Acrylic Resins; D000894:Anti-Inflammatory Agents, Non-Steroidal; D011109:Polymethacrylic Acids; D013608:Tablets, Enteric-Coated; C038300:methylmethacrylate-methacrylic acid copolymer; C050528:Eudragit RS; D007213:Indomethacin