In vitro release of disopyramide from cellulose acetate butyrate microspheres

Department of Pharmaceutics and Cardiovascular Pharmacodynamics Laboratory, College of Pharmacy, University of Georgia, Athens, GA *King Saud University, College of Pharmacy, Riyadh, Saudi Arabia.Disopyramide was microencapsulated with cellulose acetate butyrate (CAB) using an emulsion-solvent evaporation process. Drug dissolution from microcapsules was studied in both simulated gastric (SGF) and intestinal fluids (SIF) under sink conditions using the USP paddle method. There was no significant difference between drug release into SIF and SGF. As the CAB to drag ratio decreased from 3:1 to 2:1 at constant polymer mass, the drug release rate increased and the T5q% decreased from 2.3 hr to 0.3 hr for 303 fim particles. Dissolution T$o% increased from 0.4 hr to 2 hr when the mean microcapsule size was increased from 153 to 428 [im (26% drug loading). The addition of acetone to the external phase during preparation shifted the size distribution toward larger particles, but resulted in a higher drug dissolution rate for a given particle size range. A shift to smaller particles was obtained upon increasing the concentration of surfactant. The dissolution profiles were described by the Higuchi and Baker-Lonsdale equations for drug release from spherical matrices up to 90% of the drug release