title: New co-polymer zwitterionic matrices for sustained release of verapamil hydrochloride.
abstract: Stable co-polymer [vinyl acetate-co-3-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate, p(VA-co-DMAPS)] latex of different compositions has been synthesized for the first time by emulsifier-free emulsion copolymerization. The unusual >>overshooting<< behavior of the co-polymer tablets has been explained by the formation of specific clusters from the opposite oriented dipoles-zwitterionic species. The change of their concentration with the DMAPS unit fraction (mDMAPS), pH and ionic strength has been considered responsible for the differences observed in the swelling kinetics. The results obtained prove that mDMAPS and ionic strength could be used to control the swelling degree of the p(VA-co-DMAPS) matrices and their sustained drug delivery. In this way, p(VA-co-DMAPS) matrices could be effectively used to control the sustained release of drugs with basic properties like verapamil hydrochloride from model tablets.
authors.affiliation: Department of Pharmaceutical Technology and Biopharmacy, Faculty of Pharmacy, Medical University, Sofia-1000, Bulgaria. bistrakostova@abv.bg
authors.forename: Bistra
authors.initials: B
authors.lastname: Kostova
authors.forename: Dimitar
authors.initials: D
authors.lastname: Rachev
mesh_terms: D002121:Calcium Channel Blockers / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D004339:Drug Compounding; D005240:Feasibility Studies; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007840:Latex / Q000737:chemistry*; D009994:Osmolar Concentration; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D012995:Solubility; D013607:Tablets; D014700:Verapamil / Q000737:chemistry*; D014753:Vinyl Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D002121:Calcium Channel Blockers; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D007840:Latex; D000644:Quaternary Ammonium Compounds; D013607:Tablets; D014753:Vinyl Compounds; D014867:Water; D014700:Verapamil; C011566:vinyl acetate