The present study was undertaken with a view to prepare a colon targeted matrix tablets of azathioprine and evaluating in vitro drug release in presence and absence of rat ceacal. Matrix tablets containing various proportions of guar gum were prepared by wet granulation technique with the help of 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 azathioprine released from the matrix tablets was estimated by UV-visible spectrophotometer at regular time intervals. Guar gum matrix tablets released 10-16% of the azathioprine 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 performed in simulated colonic fluids the matrix tablets containing 20% of guar gum released total about 96% of azathioprine in 24 hour after degradation of tablet into 2ââ?¬â??3 pieces. The matrix tablets containing 30% of guar gum also released about 62% of azathioprine 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 30% of guar gum are most likely to provide targeting of azathioprine for local action in the colon.
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