ABSTRACT:
Targeting of drugs to the colon by the oral route could be achieved by different approaches including matrix and coated systems, for which the drug release is controlled by the gastrointestinal pH, transit times or intestinal flora. The method by which the drug release will be triggered by the colonic flora appears to be more interesting with regard to the selectivity. A number of synthetic azo polymers and natural or modified polysaccharides (chondroitin sulphate, guar gum, locust gum, inulin, dextrans, starch, amylose, pectins) degraded by the human colonic flora, have thus been investigated as colonic drug delivery carriers. Metronidazole benzoate is only used antibiotics which can be used in colonic diseases. Guar gum, Xanthan Gum, Pectin in the ratio 1:0.2, gives 99.6%, 95.45%, and 92.96% in 12 hours. In the combination of polymers Metronidazole Benzoate: Guar gum: Pectin in the ratio of 1:0.1:0.1 gives 93.79% release. In the combinations of polymers in ratio 2:1 and 5:1 (drug: polymer: polymer, 1:0.13:0.067 and 1:0.17:1:0.03) batches n8and n10 gives maximum release of drug HPMC K4M, K15M, and K100 M in ratio of 1:0.1 gives result of 99% , 95.04% and 90.47%. All these batches in first two hours i.e. hydrochloric buffer pH 1.2 shows very neglible drug release, and then in Phosphate Buffer of pH 7.0 drug release was controlled and sustained up to 12 hours. So natural polymers and some synthetic polymers like HPMC are most suitable for colon targeted drug delivery and they are economical also.