Formulation and in-vitro evaluation of microbially triggered colon specific drug delivery using sesbania gum

The aim of the present study is to develop colon targeted drug delivery systems for metronidazole using sesbania gum as a carrier. Matrix, enteric coated and compression coated tablets of metronidazole containing various proportions of sesbania gum were prepared. All the formulations were evaluated for the hardness, drug content uniformity, and were subjected to in vitro drug release studies. Matrix tablets and enteric coated tablets of metronidazole released 41–71% and 25–28% of the metronidazole, respectively, in the physiological environment of stomach and small intestine depending on the proportion of sesbania gum used in the formulation. Both the formulations failed to control the drug release within 5 hr. The compression coated formulations (CS2) released less than 5% of metronidazole in the physiological environment of stomach and small intestine. When the dissolution study was continued in simulated colonic fluids, the compression coated tablet with 150 mg of sesbania gum coat released another 76% of metronidazole after degradation by colonic bacteria at the end of 12 hr.