Preparation and Characterization of Ethylcellulose-Walled Theophylline Microcapsules Using the Emulsion-Solvent Evaporation Technique

Ethylcellulose microcapsules containing theophylline are prepared by emulsification of a organic ethylcellulose solution in a oil phase containing a surfactant. The preparation is based on dispersion of acetone containing the drug in liquid paraffin. Tween 80 was used as a dispersing agent. Good reproducibility in microcapsule preparation was observed. The microcapsules obtained were uniform and free-flowing particles. The type of the stirring-manner (propella – and magnet – stirring), and the drug to polymer ratios have an important influence on the in vitro dissolution and release of theophylline from microcapsules.