THE ROLES OF CHANNELING AGENTS ON THE DRUG RELEASE FROM WAX MATRIX TABLETS PREPARED BY MELT GRANULATION

The study aimed to investigate the effect of the channeling agents and to explore the mechanisms by which they affect the drug release from wax matrix tablets.  The channeling agents were potato starch and icing sugar. The wax matrix tablet contained 4% w/w of chlorpheniramine maleate, a model drug. The matrix formers were carnauba wax, the mixtures of wax and potato starch or icing sugar with different weight ratio of wax: channeling agent, i.e., 1:1, 1:2, and 2:1. They were prepared by melt granulation and then compression into tablet. The in vitro drug release from the wax matrix tablets was studied using USP II (Paddle) method. Within 8 hours, only 22.26% of the drug released from the neat wax matrix tablet, whereas the drug release was significantly increased from tablets containing a channeling agent. The rate and the extent of the drug released increased linearly with the increasing amounts of potato starch. Unlike icing sugar, it had less effect on enhancing the drug release at concentrations of 33% and 50%, but at 67%, the dramatic increase of the drug release was attained. This discrepancy was attributed to the nature and different mechanisms of the two channeling agents on promoting the drug release. The SEM micrographs as well as the degree of water uptake and tablets erosion clearly demonstrated the roles of these two channeling agents on the drug release. The release profiles of the drug from all matrices followed Higuchi model showing the r 2 of 0.97-0.99. Keywords : Carnauba wax; Chlorpheniramine maleate; Higuchi diffusion model;  Icing sugar; Melt granulation; Potato starch;