Natural polysaccharides as targeting tools of drugs to the human colon

The ability to deliver drugs to the human colon in a specific manner has become feasible in the last decade. A variety of means, including protective coats and pH-dependent polymers, are currently in use. Utilization of the metabolic activity of the colon is an attractive implement to improve the drug carriers' specificity. Biodegradable polymers, which are cleaved by colonic enzymes, can be used for that purpose. The mechanism of choice is azo-reduction and glycosidic-bond hydrolysis. In this review, some of the most common approaches to target drugs to the colon are reviewed and special attention is paid to modified polysaccharides as potential drug carriers to the human colon. (C) 2000 Wiley-Liss, Inc.