title: Evaluation of the properties of ethylcellulose-cellulose triacetate microcapsules containing theophylline prepared by different microencapsulation techniques.
abstract: Using cellulose triacetate as an added complementary coating material in preparing sustained-release ethylcellulose-cellulose triacetate microcapsules of theophylline, three microencapsulation techniques were investigated. Ethylcellulose-cellulose triacetate composite microcapsules, ethylcellulose-cellulose triacetate dual-walled microcapsules and ethylcellulose microcapsules containing cellulose triacetate matrices were prepared using the non-solvent addition phase separation method. The effects of cellulose triacetate on the release of theophylline from the different ethylcellulose-cellulose triacetate microcapsules were obtained from dissolution studies. The results showed that the release rates of ethylcellulose-cellulose triacetate microcapsules were slower than those obtained from the ethylcellulose microcapsules prepared with similar core to wall ratios. The ethylcellulose microcapsules containing cellulose triacetate matrices had longer release half-times and smaller surface areas than the other capsule preparation. The release patterns of theophylline from the different ethylcellulose-cellulose triacetate microcapsules fitted first-order kinetics. Scanning electron micrographs showed that the surfaces of various ethylcellulose-cellulose triacetate microcapsules were different from those of theophylline, cellulose triacetate matrices of cellulose triacetate microcapsules, and that the surface morphology of ethylcellulose-cellulose triacetate microcapsules was affected by the preparative method.
authors: Department of Chemical Engineering, National Central University, Chung-Li, Taiwan, ROC.
authors: J C
authors: JC
authors: Wu
authors: W J
authors: WJ
authors: Jean
authors: H
authors: H
authors: Chen
mesh_terms: D002214:Capsules; D002482:Cellulose / Q000031:analogs & derivatives* / Q000737:chemistry; D002626:Chemistry, Pharmaceutical / Q000379:methods; D003692:Delayed-Action Preparations; D004339:Drug Compounding / Q000379:methods; D005069:Evaluation Studies as Topic; D007700:Kinetics; D008855:Microscopy, Electron, Scanning; D013499:Surface Properties; D013806:Theophylline / Q000008:administration & dosage* / Q000737:chemistry*
chemical_list: D002214:Capsules; D003692:Delayed-Action Preparations; C013517:ethyl cellulose; D002482:Cellulose; C024671:cellulose triacetate; D013806:Theophylline