title: pH-independent release of a basic drug from pellets coated with the extended release polymer dispersion Kollicoat SR 30 D and the enteric polymer dispersion Kollicoat MAE 30 DP.
abstract: The objective of this study was to obtain pH-independent release profiles from coated pellets containing drugs with pH-dependent solubility. pH-independent release of the basic model drug verapamil HCl was achieved by coating with a combination of the neutral polymer dispersions Kollicoat SR 30 D (aqueous dispersion of polyvinyl acetate) and the enteric polymer dispersion Kollicoat MAE 30 DP (aqueous dispersion of methacrylic acid and ethyl acrylate copolymer; methacrylic acid copolymer type C). The two polymers where applied either as separate layers (enteric polymer + extended release polymer or vice versa) or as a polymer blend. A careful balance of the ratios of the polymers allowed the achievement of a pH-independent release. Higher amounts of the enteric polymer in the polymer blend resulted in a reversal of the pH-dependency, e.g. a faster release at pH 6.8 than in 0.1 N HCl.
authors.affiliation: College of Pharmacy, Freie Universität Berlin, Berlin, Germany. dashevsk@zedat.fu-berlin.de
authors.forename: A
authors.initials: A
authors.lastname: Dashevsky
authors.forename: K
authors.initials: K
authors.lastname: Kolter
authors.forename: R
authors.initials: R
authors.lastname: Bodmeier
mesh_terms: D003692:Delayed-Action Preparations / Q000737:chemistry / Q000493:pharmacokinetics; D004343:Drug Implants; D006863:Hydrogen-Ion Concentration; D011108:Polymers / Q000737:chemistry / Q000493:pharmacokinetics; D011109:Polymethacrylic Acids / Q000737:chemistry / Q000493:pharmacokinetics*; D011145:Polyvinyls / Q000737:chemistry / Q000493:pharmacokinetics*
chemical_list: D003692:Delayed-Action Preparations; D004343:Drug Implants; D011108:Polymers; D011109:Polymethacrylic Acids; D011145:Polyvinyls; C117135:kollicoat MAE 30 D; C013215:polyvinyl acetate