An in vitro and in vivo investigation into the suitability of bacterially triggered delivery system for colon targeting.

The colon specific drug delivery systems based on polysaccharides; locust bean gum and chitosan in the ratio of 2 : 3, 3 : 2 and 4 : 1 were evaluated using in vitro and in vivo methods. The in vitro studies in pH 6.8 phosphate buffer containing 2% w/v rat caecal contents showed that the cumulative percentage release of mesalazine after 26 h were 31.25+/-0.56, 46.25+/-0.96, 97.5+/-0.26 (mean+/-S.D.), respectively. The in vivo studies conducted in nine healthy male human volunteers for the various formulations revealed that, the drug release was initiated only after 5 h (i.e.) transit time of small intestine and the bioavailability (AUC(0-->t*)) of the drug was found to be 85.24+/-0.10, 196.08+/-0.12, 498.62+/-0.10 microg x h/ml 26 (mean+/-S.D.), respectively. These studies on the polysaccharides demonstrated that the combination of locust bean gum and chitosan as a coating material proved capable of protecting the core tablet containing mesalazine during the condition mimicking mouth to colon transit. In particular, the formulation containing locust bean gum and chitosan in the ratio of 4 : 1 held a better dissolution profile, higher bioavailability and hence a potential carrier for drug targeting to colon.