osmotic controlled. Microbial triggered.

The major goal of any drug delivery system is to supply a therapeutic amount of drug to the target site in the body, in order to achieve desired drug concentration. Colon targeted drug delivery system involves the targeting of drug to colon and is used for the treatment of various diseases related to colon like inflammatory bowel disease, colon cancer, crohn’s diseases etc. Targeting to colon directly reduces the need of higher dose, dosing frequency, incidence of side effects and cost effective treatment can also be achieved. Colon was considered as “BLACK BOX” and generally absorption of most drugs occur in upper G.I region. Lack of digestive enzymes and delayed gastric emptying, has given the idea to design colon specific drug delivery system. This review article compares the different approaches to colon targeted drug delivery like pH and time dependent, prodrug, microbial triggered and pulsatile drug delivery system etc. Beside these different new approaches were also used for colon targeting like pressure controlled, osmotic controlled drug delivery systems are highly effective.