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 be come feasible in the last decade. A variety of means, including protective coats and pH-dependent polymers, are currently in use. Utilization of the m etabolic activity of the colon is an attractive implement to improve the dr ug carriers' specificity. Biodegradable polymers, which are cleaved by colo nic enzymes, can be used for that purpose. The mechanism of choice is azo-r eduction and glycosidic-bond hydrolysis. In this review, some of the most c ommon approaches to target drugs to the colon are reviewed and special atte ntion is paid to modified polysaccharides as potential drug carriers to the human colon. (C) 2000 Wiley-Liss, Inc.