title: Sustained release chitosan microspheres prepared by novel spray drying methods.
abstract: Modified spray drying methods, especially a novel w/o/w emulsion-spray drying method, were developed to prepare chitosan microspheres with a sustained drug release pattern. Release of the model drugs cimetidine and famotidine, from the microspheres prepared by the emulsion-spray drying methods, was greatly retarded with release lasting for several hours, compared with drug loaded microspheres prepared by conventional-spray drying or emulsion methods where drug release was almost instant. The slow release of drug was partly due to the poor wetting ability of the microspheres which floated on the surface of the dissolution medium. The addition of a wetting agent increased the release rate significantly. The coating of the microspheres with gelatin decreased the rate of release of drug in the presence of wetting agents.
authors.affiliation: Department of Pharmaceutical Science, University of Nottingham, UK.
authors.forename: P
authors.initials: P
authors.lastname: He
authors.forename: S S
authors.initials: SS
authors.lastname: Davis
authors.forename: L
authors.initials: L
authors.lastname: Illum
mesh_terms: D000336:Aerosols; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry; D048271:Chitosan; D002927:Cimetidine / Q000737:chemistry; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D004655:Emulsions / Q000737:chemistry; D015738:Famotidine / Q000737:chemistry; D005612:Freeze Drying; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D009330:Nebulizers and Vaporizers; D016567:Nizatidine / Q000737:chemistry; D010316:Particle Size; D011136:Polysorbates; D013500:Surface Tension; D014906:Wetting Agents
chemical_list: D000336:Aerosols; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D004655:Emulsions; D011136:Polysorbates; D014906:Wetting Agents; D002686:Chitin; D015738:Famotidine; D002927:Cimetidine; D048271:Chitosan; D016567:Nizatidine