Formulation and Evaluation of Colon Targeted Oral Drug Delivery Systems for Metronidazole in Treatment of Amoebiasis

The aim of present study was to develop colon targeted system for metronidazole using guar gum and xanthan gum. Matrix formulations containing various proportions of guar gum and xanthan gum were prepared by wet granulation technique using 10% starch paste. Later on, multilayer tablets were prepared by using 50 mg and 100 mg of guar gum as release controlling layer on either side of (M5) guar gum matrix tablets of metronidazole. All the formulations were evaluated for in-process quality control tests. The in-vitro drug release study was undertaken at 37±0.5°C in 0.1N HCl for 2 h; followed by pH 7.4 phosphate buffer (3h) finally in, simulated colonic fluid pH 6.8 phosphate buffer containing 4%w/v rat ceacal content for 15 h. Results indicated that guar gum was alone failed to control drug release. M5 (GG: XG, 0:100) formulation seems to quiet promising for colonic drug delivery and only 12.3% drug is released in first 5h wherease, other matrix tablets released 12-33% of metronidazole in physiological environment of stomach and small intestine. When studies were continued in colonic fluids, matrix tablets released almost 100% drug. whereas, metronidazole multilayer formulations did not release drug in stomach and small intestine, but delivered drug to the colon resulting in slow absorption of the drug and making drug available for local action in the colon