Current applications of polysaccharides in colon targeting.

Polysaccharides have over the years been used widely in pharmaceutical, chemical, and biochemical drug delivery. This family of natural polymers has an appeal to the area of drug delivery as it is comprised of polymers with a large number of derivatizable groups, a wide range of molecular weights, varying chemical compositions, and for the most part, a low toxicity and biodegradability, yet a high stability. The main scope of this review is to relate the polysaccharides available now to the rapidly growing field of colonic drug delivery. Polysaccharides have been applied to the area as controlled release coatings, matrices, macromolecular carriers, and biodegradable carriers. Bacterial sources of polysaccharidases as well as a detailed treatise of the enzymatic flora of the colonic region are discussed, followed by a presentation of the polysaccharides available for the purpose of colon-specific drug delivery. A final overview of the various approaches to obtain colon-specific delivery by using polysaccharides and a summary of available in vitro and in vivo testing methods will lead to the conclusion that polysaccharides at this point appear to be very promising compounds for use in obtaining colon-specific drug delivery systems.