Betty Philip

The colon is a site where both local and systemic delivery of drugs can take place. Local delivery allows topical treatment of inflammatory bowel disease. However, treatment can be made effective if the drugs can be targeted directly into the colon, thereby reducing the systemic side effects. This review, mainly compares the primary approaches for CDDS (Colon Specific Drug Delivery) namely prodrugs, pH and time dependent systems, and microbially triggered systems, which achieved limited success and had limitations as compared with newer CDDS namely pressure controlled colonic delivery capsules, CODESTM, and osmotic controlled drug delivery which are unique in terms of achieving in vivo site specificity, and feasibility of manufacturing process. Department of Pharmaceutics, School of Pharmacy, University of Nizwa, Birkat Al Mouz, Nizwa-616, Sultanate of Oman. Received: 07 Feb 2010 Accepted: 14 Mar 2010 Address correspondence and reprint request to: Dr. Anil K. Philip, Assistant Professor Department of Pharmaceutics, School of Pharmacy, College of Pharmacy and Nursing, University of Nizwa, Birkat Al Mouz, Nizwa-616, Sultanate of Oman. E-mail: [email protected], [email protected] Philip AK, et al. OMJ. 25, 70-78 (2010); doi:10.5001/omj.2010.24 Colon Targeted Drug Delivery Systems: A Review on Primary and Novel Approaches of ulcerative colitis. Although these drugs are absorbed from the large bowel, it is generally believed that their efficacy is due mainly to the topical application. The concentration of drug reaching the colon depends on formulation factors, the extent of retrograde spreading and the retention time. Foam and suppositories have been shown to be retained mainly in the rectum and sigmoid colon while enema solutions have a great spreading capacity.7 Because of the high water absorption capacity of the colon, the colonic contents are considerably viscous and their mixing is not efficient, thus availability of most drugs to the absorptive membrane is low. The human colon has over 400 distinct species of bacteria as resident flora, a possible population of up to 1010 bacteria per gram of colonic contents. Among the reactions carried out by these gut flora are azoreduction and enzymatic cleavage i.e. glycosides.8 These metabolic processes may be responsible for the metabolism of many drugs and may also be applied to colontargeted delivery of peptide based macromolecules such as insulin by oral administration. Table 1: Colon targeting diseases, drugs and sites Target sites Disease conditions Drug and active agents