title: Encapsulation of chlorothiazide in whey proteins: effects of wall-to-core ratio and cross-linking conditions on microcapsule properties and drug release.
abstract: A model drug with limited water-solubility, chlorothiazide, was successfully encapsulated in whey protein-based wall systems cross-linked by glutaraldehyde-saturated toluene via an organic phase. The effects of drug content of the core-in-wall suspension and of cross-linking conditions on core retention and on microcapsule size, structure and core release properties were investigated. Spherical, surface cracks-free microcapsules ranging in diameter from approximately 200-1300 microm were obtained. Particle size distribution of microcapsules was affected by core content and cross-linking conditions. Core retention in microcapsules prepared at different cross-linking conditions and different wall-to-core ratios ranged from 48.9-81%, from 42.2-76.1% and from 37.3-67.2% in large (L), medium-size (M) and small (S) microcapsules, respectively. In all cases, drug crystals were physically entrapped and embedded throughout the cross-linked protein matrix. Core release from the microcapsules into enzyme-free simulated gastric fluid was governed by a diffusion-controlled mechanism and did not involve erosion or softening of the wall matrix. Rate of core release was significantly affected by a combined influence of core content, microcapsule size and cross-linking density. Complete core release from L, M and S microcapsule prepared at different wall-to-core ratios and cross-linking conditions ranged from 28.6-81.2 h, from 16.8-28.6 h and from 7.2-15.9 h, respectively. Results suggested that whey protein-based wall matrix cross-linked by GAST may provide significant opportunities in modulating the release of an encapsulated core with a limited water solubility.
authors.affiliation: Department of Food Science and Technology, University of California, Davis, CA 95616, USA.
authors.forename: G
authors.initials: G
authors.lastname: Satpathy
authors.forename: M
authors.initials: M
authors.lastname: Rosenberg
mesh_terms: D000959:Antihypertensive Agents / Q000737:chemistry* / Q000493:pharmacokinetics; D002214:Capsules; D002740:Chlorothiazide / Q000737:chemistry* / Q000493:pharmacokinetics; D003432:Cross-Linking Reagents / Q000493:pharmacokinetics; D003692:Delayed-Action Preparations / Q000493:pharmacokinetics; D004058:Diffusion; D004339:Drug Compounding / Q000379:methods; D008855:Microscopy, Electron, Scanning; D008894:Milk Proteins / Q000737:chemistry* / Q000493:pharmacokinetics; D010316:Particle Size; D012995:Solubility; D014867:Water; D000067816:Whey Proteins
chemical_list: D000959:Antihypertensive Agents; D002214:Capsules; D003432:Cross-Linking Reagents; D003692:Delayed-Action Preparations; D008894:Milk Proteins; D000067816:Whey Proteins; D014867:Water; D002740:Chlorothiazide