Development of guar gum-alginate based microcapsules of metronidazole for delivery to colon

The present study was aimed to develop and evaluate suitable guar gum-alginate microcapsules for colon-specific delivery of Metronidazole for better treatment of amoebic colitis (important cause of death in the developing countries). Microcapsules were prepared by calcium chloride cross-linking method with different concentrations of sodium alginate and guar gum. Prepared microcapsules were treated for three different coatings with reduced molecular weight guar gum, chitosan and enteric coatings with cellulose acetate phthalate (CAP). Microcapsules were evaluated for size and morphology, thickness, strength and flexibility and drug content. In vitro drug release study was conducted by buffer change method to mimic G1T environment. In morphological study, the guar gum membrane was found to be transparent, porous and continuous in nature. Guar gum concentrations significantly affected the strength and flexibility of membrane. Drug loading was decreased with increase in the weight of either encapsulating polymer or guar gum and different coatings. In vitro drug release was found to be marginally decreased with increasing guar gum and alginate concentrations. The coated microcapsules exhibited significantly retarded and colon specific drug release as compared to uncoated microcapsules. Among the coatings, reduced molecular weight guar gum coating gave much lower drug release and also exhibited high colon specificity.