title: Controlled release of theophylline from inert matrices: effect of channeling material on release rate.
abstract: Sustained release theophylline tablets containing stearic acid wax and lactose fast flo as chanelling agent were prepared and evaluated. The fusion technique was used for dispersing the drug in the different levels of stearic acid. The release rate of theophylline from the prepared tablets increased with the increase of the level of the channeling material in the formula. The drug release from tablets containing high level of wax (30 and 60%) and low level of channeling material (59% and 29%) followed the diffusion controlled model for inert porous matrix. The drug release increased significantly with the increase of lactose fast flow level in the formula. After 2 hours of testing dissolution, the tablets start to erode and the mechanism of drug release deviate from the diffusion controlled model. The mechanism of drug release was dependent on the level of the channeling material in the matrix.
authors.affiliation: University of Puerto Rico, School of Pharmacy, Department of Pharmaceutical Sciences, San Juan 00936-5067.
authors.forename: E S
authors.initials: ES
authors.lastname: Ghaly
authors.forename: M I
authors.initials: MI
authors.lastname: Malavé
authors.forename: W J
authors.initials: WJ
authors.lastname: Rivera
authors.forename: A
authors.initials: A
authors.lastname: Martí
mesh_terms: D002626:Chemistry, Pharmaceutical / Q000379:methods*; D003692:Delayed-Action Preparations; D016503:Drug Delivery Systems; D015195:Drug Design; D007785:Lactose; D013229:Stearic Acids; D013607:Tablets; D013806:Theophylline; D013997:Time Factors
chemical_list: D003692:Delayed-Action Preparations; D013229:Stearic Acids; D013607:Tablets; C031183:stearic acid; D013806:Theophylline; D007785:Lactose