An overview of commercially available polymers for colon-targeted drug delivery systems

The colon consists of the cecum, transverse colon, ascending colon, descending colon, and sigmoid colon. Colonic diseases such as inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), colon cancer, and various other conditions may occur due to alterations in pathophysiology or factors such as environmental influences, dietary habits, and immunological variations. Conventional oral dosage forms require higher doses and pose the risk of exposing non-colonic tissues to the drug, potentially leading to adverse reactions. Successful colon targeting can be accomplished achieved by leveraging factors such as variations of gastro-intestinal pH, gastro-intestinal transit time, and colonic microflora- which secrete a plethora of complex polysaccharide-digesting enzymes. Colon-targeted drug delivery systems (CTDDS) are designed to release the drug specifically within the colon. Therefore, the development of specialized polymers is crucial for the effectiveness of CTDDS. The aim of this review is to focus on the various commercially available polymers used in CTDDS, including their origins, chemical and physical properties, and their applications to date. Additionally, the authors have discussed the methods for formulating targeted release dosage forms for CTDDS and explored their colon targeting efficiency based on study results to identify suitable polymers for this purpose.