title: Mechanistic study on hydration and drug release behavior of sodium alginate compacts.
abstract: The influence of sodium alginate viscosity on the dynamics of matrix hydration, solvent front movement, swelling, erosion, and drug release from alginate matrix tablets were examined. The solvent front showed preferential penetration from the radial direction even though matrix swelling showed axial predominance. This study proposed alternative views for the anisotropic behavior of hydrating alginate compacts, namely, formation of gel barrier with different permeability characteristics, tension at the gel-core interface and preferential radial erosion, in addition to an in-depth examination on the contribution of stress relaxation of hydrated polymer as well as core expansion. Alginate matrices demonstrated pH-dependent hydration, swelling and erosion behavior, resulting in pH-dependent drug release mechanisms. Dissolution profiles for alginate matrices of different viscosities were similar in acid but differed upon increase of pH. This was due to the influence of alginate viscosity grade on liquid uptake, erosion and pronounced swelling at near neutral pH.
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: Ai Ling
authors.initials: AL
authors.lastname: Ching
authors.forename: Celine Valeria
authors.initials: CV
authors.lastname: Liew
authors.forename: Paul Wan Sia
authors.initials: PW
authors.lastname: Heng
mesh_terms: D000464:Alginates / Q000737:chemistry*; D016880:Anisotropy; D002626:Chemistry, Pharmaceutical; D002744:Chlorpheniramine / Q000737:chemistry; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D012995:Solubility; D013607:Tablets; D014783:Viscosity
chemical_list: D000464:Alginates; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D006603:Hexuronic Acids; D013607:Tablets; D002744:Chlorpheniramine; D020723:Glucuronic Acid