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Preparation and characterization of azathioprine microspheres for colon specific delivery

The objective of the present study is to develop colon targeted drug delivery system using dextrin (polysaccharide) as a carrier for Azathioprine.  Microspheres containing azathioprine, dextrin and various excipients were prepared by solvent evaporation technique. The prepared microsphere were evaluated by different methods parameters like particle size,  drug entrapment efficiency, percentage yield, shape and surface morphology  and in vitro drug release study. Drug release profile was evaluated in simulated gastric, intestinal fluid and simulated colonic fluid. Best formulation was decided on the basis drug release profile in simulated gastric, intestinal fluid and simulated colonic fluid. In dextrin based microspheres, dextrin as a carrier was found to be suitable for targeting of Azathioprine for local action in the site of colon. Dextrin microspheres released 95-99% of azathioprine in simulated colonic fluid with 4% human fecal matter solution. The results of in-vitro studies of the azathioprine microspheres indicate that for colon targeting dextrin are suitable carriers to deliver the drug specifically in the colonic region. Dextrin based azathoprine microspheres showed no significance change in particle size and % residual upon storage at 5 ± 3ºC, 25 ± 2ºC/60 ± 5% RH (room temperature) and 40 ± 2ºC/75 ±5%RH humidity for three months. 
Keywords: azathioprine, microsphere, dextrin, colon specific drug delivery.