FORMULATION DESIGN, IN-VITRO AND BIOLOGICAL CORRELATION OF SITE SPECIFIC DRUG DELIVERY SYSTEM FOR DISTAL GASTRO-INTESTINAL TRACT

The present study was designed to evaluate oral compression coated tablet formulation to achieve time and site specific drug release system to target lower GIT. A pectin based compression coated tablet formulation of different ratios and concentration of ethyl cellulose and cellulose acetate phthalate were designed and evaluated physico chemical parameters and for tinidazole release, compression coated tablet formulation 7.5% : 7.5% ethyl cellulose:cellulose acetate phthalate showed controlled drug release, were formulation showed no evidence of drug release in pH 1.2, but drug released was in simulated intestinal fluid pH 7.4  after 5 hours, further drug release continued  in pH 6.8 i.e. pH of colon for 24 hours and was 87.38% after 24 hour, suited for colon specific drug delivery, on subjecting the selected formulation to in vitro microbial disintegration studies, the disintegration started within 4 hours of incubation period indicates that the usefulness of pectin in the formulation, were pectin is microbially hydrolysable  and complete disintegration was observed after 16 hours. In vivo oral disintegration/ degradation the result was found to be correlated in their disintegration pattern with microbial disintegration. Finally the images of gamma Scintigraphic studies revealed that the disintegration of the tablet formulation on reaching colon