Matrix Assisted Solid Oral Dosage Form of Metronidazole for Colon Specific Delivery

摘要

The aim of the study was to formulate a dosage form for Metronidazole (MTZ) that will specifically deliver the drug into the colon. The approach based on a combination of pH-dependent and time-controlled release mechanism was used. pH-dependent release can be assured by enteric coating and drug release was delayed further for a predetermined time during transit through the small intestine. Effect of use of polymers as both matrices and binders in the tablet formulation was evaluated by in vitro release studies. All the batches of formulations were prepared and evaluated by various parameters -Weight variation, Size, Hardness, Friability, and Determination of Drug Contents.Guar gum,xanthan gum matrix tablets were formulated using different polymers such as Chitosan Eudragit E, Eudragit S-100, as binders, varying the matrix material as well as binder and their concentration affects drug release from the prepared tablets.In the combination of guar gum-xanthan gum matrix tablets, as the amount of xanthan gum was increased into the tablet, the drug release rate decreased but increase in swelling was seen due to the gel forming property of gum. Swelling was more in xanthan gum in as compared to guar gum matrix tablets of MTZ. Swelling increased as the concentration of matrix material i.e. gum was increased. Swelling tendency was more prominent in tablets containing combination of both guar gum and xanthan gum.The susceptibility of matrix tablet containing guar gum/ xanthan gum to the enzymatic activity of colonic bacteria was assessed by conducting the drug release studies in pH 6.8 phosphate buffer containing rat caecal contents because of their similarity with those of humans with respect to intestinal microflora .The presence of rat caecal content in dissolution medium resulted in an appreciable increase in drug release because of the presence of micro organism in the rat caecal content, which caused faster biodeeradation of polymer.