FORMULATION AND EVALUATION OF COLON TARGETED MATRIX TABLET USING NATURAL TREE GUMS

Objective: To develop a novel colon targeted tablet formulation using natural polysaccharides such as kondagogu gum and ghatti gum as carriers and diltiazem hydrochloride as a model drug.Methods: The polymer-drug tablets were prepared by wet granulation technique, coated with two layers viz., inulin as an inner coat followed by shellac as outer coat and evaluated for properties such as average weight, hardness and coat thickness. In vitro release studies of prepared tablets were carried out for 2 h in pH 1.2 HCl buffer, 3 h in pH 7.4 phosphate buffer and 6 h in simulated colonic fluid (SCF) in order to mimic the conditions from mouth to colon.Results: Percentage weight variation, percent friability and content of active ingredient for all the formulations were found to be well within United States Pharmacopoeia (USP) limits. Out of both the polymers, the tablets prepared with ghatti gum showed the maximum hardness of 7.1 kg/cm2. The FTIR spectra of pure diltiazem HCl and the formulation KF3 were found to be identical. From the DSC, it was evident that the melting point peak of diltiazem HCl and formulation KF3 were observed at 217.16 and 218.34 °C respectively. In vitro studies revealed that the tablets coated with shellac (2.5% w/w), prevented the drug release in stomach environment and inulin coated tablets (4% w/w) have limited the drug release in the small intestinal environment. The data obtained from in vitro drug release studies were fit into Peppas model and in all the cases the value of A was found to be more than 2, i.e., drug release by a combination of both diffusion and erosion-controlled drug release.Conclusion: The study revealed that polysaccharides as carriers and inulin and shellac as a coating material can be used effectively for colon targeting of drugs for treating local as well as systemic disorders.