Carbohydrate polymers: Applications and recent advances in delivering drugs to the colon

Colon specific delivery gained increasing importance for the treatment colonic diseases, such as colorectal cancer, amebiasis, ulcerative colitis and Crohn's disease. Different strategies are used for targeting drugs to the colon include enzymatically degradable polymers, prodrug based approach, coating with time or pH-dependent polymers, osmotically controlled and pressure-controlled drug delivery systems. Polysaccharides that are precisely activated by the physiological environment of the colon hold great promise, as they provide improved site specificity and meet the desired therapeutic needs. The colon specific delivery systems based on a single polysaccharide do not efficiently permit targeted release. The pH and transit time can vary depending on the individual and the particular disease state. The conventional approaches give rise to premature drug release. The combination/chemically modified forms of polysaccharides eliminated the drawbacks associated with the use of single polysaccharide. This review focus on approaches to emerging discipline, revisits the existing technologies and future development. (c) 2011 Elsevier Ltd. All rights reserved.