2. In-vitro studies of xanthan gum based formulation of Albendazole for colon targeted delivery

Colon targeted controlled release matrix tablets of Albendazole were prepared using xanthan gum (XG). The ability of the prepared matrices to retard drug release in the upper gastrointestinal tract and to undergo enzymatic hydrolysis by the colonic bacteria was evaluated. In vitro drug release studies were carried out in the presence of rat caecal content. Optimum release was observed with Albendazole formulation containing 30% and 40% xanthan gum. The rate of drug release was found to be decreased with increase in the concentration of xanthan gum due to high swelling, which made them more vulnerable to digestion by the microbial enzymes in the colon. The in vitro drug release studies reveal that the formulations containing 40% xanthan gum followed zero order kinetics and the mechanism of release is anomalous or non-Fickian. Formulations containing 30% xanthan gum followed zero order kinetics via Fickian diffusion. Significance difference was observed between drug release in dissolution medium with and without rat cecal contents for the optimum batches of Albendazole tablets (P<0.05).