title: Liquid phase coating to produce controlled-release alginate microspheres.
abstract: This study explored a liquid phase coating technique to produce polymethyl methacrylate (PMMA)-coated alginate microspheres. Alginate microspheres with a mean diameter of 85.6 microm were prepared using an emulsification method. The alginate microspheres, as cores, were then coated with different types of PMMA by a liquid phase coating technique. The release characteristics of these coated microspheres in simulated gastric (SGF) and intestinal (SIF) fluids and the influence of drug load on encapsulation efficiency were studied. The release of paracetamol, as a model hydrophilic drug, from the coated microspheres in SGF and SIF was greatly retarded. Release rates of Eudragit RS100-coated microspheres in SGF and SIF were similar as the rate-controlling polymer coat was insoluble in both media. Drug release from Eudragit S100-coated microspheres was more sustained in SGF than in SIF, due to the greater solubility of the coating polymer in media with pH greater than 7.0. The drug release rate was affected by the core:coat ratio. Drug release from the coated microspheres was best described by the Higuchi's square root model. The liquid phase coating technique developed offers an efficient method of coating small microspheres with markedly reduced drug loss and possible controlled drug release.
authors.affiliation: Department of Pharmacy, Faculty of Science, National University of Singapore, Singapore.
authors.forename: Lai Wah
authors.initials: LW
authors.lastname: Chan
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Liu
authors.forename: Paul Wan Sia
authors.initials: PW
authors.lastname: Heng
mesh_terms: D000082:Acetaminophen; D000464:Alginates; D018712:Analgesics, Non-Narcotic; D001826:Body Fluids / Q000378:metabolism; D003692:Delayed-Action Preparations; D004339:Drug Compounding / Q000379:methods; D005753:Gastric Mucosa / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000378:metabolism; D008863:Microspheres; D008954:Models, Biological; D010316:Particle Size; D011109:Polymethacrylic Acids; D019904:Polymethyl Methacrylate; D012995:Solubility; D013499:Surface Properties
chemical_list: D000464:Alginates; D018712:Analgesics, Non-Narcotic; D003692:Delayed-Action Preparations; D011109:Polymethacrylic Acids; C038300:methylmethacrylate-methacrylic acid copolymer; D000082:Acetaminophen; D019904:Polymethyl Methacrylate