title: The effect of core-to-wall ratio and Span 80 concentration on the properties of ascorbic acid microcapsules.
abstract: Ethylcellulose microcapsules containing ascorbic acid were prepared by the emulsification-solvent evaporation technique. The effect of core-to-wall ratios and surfactant concentrations on the dissolution rate and size distribution of the ascorbic acid microcapsules were studied. Span 80 was used as a dispersing agent and light liquid paraffin as a continuous phase. The dissolution of ascorbic acid microcapsules was studied using the USP rotating basket method. A high core-to-wall ratio resulted in an increase of both microcapsule size and drug release rate. For a given core-to-wall ratio a high concentration of Span 80 increased the drug release rate, this was associated with the presence of drug crystals on the microcapsule surface.
authors.affiliation: Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand.
authors.forename: D
authors.initials: D
authors.lastname: Vanichtanunkul
authors.forename: P
authors.initials: P
authors.lastname: Vayumhasuwan
authors.forename: U
authors.initials: U
authors.lastname: Nimmannit
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D001205:Ascorbic Acid / Q000737:chemistry*; D002214:Capsules; D002482:Cellulose / Q000031:analogs & derivatives / Q000737:chemistry; D055598:Chemical Phenomena; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D002627:Chemistry, Physical; D002851:Chromatography, High Pressure Liquid; D006601:Hexoses / Q000737:chemistry*; D007700:Kinetics; D010316:Particle Size; D012997:Solvents / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D002214:Capsules; D006601:Hexoses; D012997:Solvents; D013501:Surface-Active Agents; C018665:sorbitan monooleate; C013517:ethyl cellulose; D002482:Cellulose; D001205:Ascorbic Acid