Development of colon targeted drug delivery systems for mebendazole

The objective of the present study is to develop colon targeted drug delivery systems for mebendazole using guar gum as a carrier. Matrix tablets containing various proportions of guar gum were prepared by wet granulation technique using starch paste as a binder. The tablets were evaluated for drug content uniformity, and were subjected to in vitro drug release studies. The amount of mebendazole released from the matrix tablets at different time intervals was estimated by a high-performance liquid chromatography method. Guar gum matrix tablets released 8-15% of the mebendazole in the physiological environment of stomach and small intestine depending on the proportion of guar gum used in the formulation. When the dissolution study was continued in simulated colonic fluids the matrix tablets containing 20% of guar gum released another 83% of mebendazole after degradation into 2-3 pieces. The matrix tablets containing 30% of guar gum also released about 50% of mebendazole in simulated colonic fluids indicating the susceptibility of the guar gum formulations to the rat caecal contents. The results of the study show that matrix tablets containing either 20% or 30% of guar gum are most likely to provide targeting of mebendazole for local action in the colon. The mebendazole matrix tablets containing either 20% or 30% of guar gum showed no change either in physical appearance, drug content or dissolution pattern after storage at 45 degrees C/75% relative humidity for 3 months. Differential scanning calorimetry indicated no possibility of interaction between mebendazole and guar gum.