Oral colon-specific drug delivery: a review

Abstract

The development of delivery systems which enable selective release of drugs in the large intestine has gained much interest during the past decade. Two important therapeutic applications which can be found for oral colon-specific drug delivery are the treatment of local disorders of the colon and the delivery of protein and peptide drugs via the oral route. With the explosion of new peptide and protein products under development in the biotechnology industry, there has been increasing interest in utilizing the colon as site for drug absorption. Indeed, the large intestine may be the best site for peptide delivery because of the high residence time and the low digestive enzymatic activity. Due to the localization of the colon, it is difficult to reach. However, using different approaches, several potential colonic targeting systems have been developed. Among these, the most promissing are coating drugs with pH-sensitive and bacterial degradable polymers; delivery of drugs through bacterial degradable hydrogels or matrix systems; and delivery of drugs via bacterial degradable prodrugs. A major advantage of delivery systems based upon colon-specific enzymes from bacterial origin is the site-specificity. Therefore, other enzyme systems of bacterial origin may be explored in the future.