Oral delivery of drugs to the colon is valuable in the treatment of diseases of colon (ulcerative colitis, Chron's disease, carcinomas and infections) whereby high local concentration can be achieved while minimizing side effects that occur because of release of drugs in the upper GIT or unnecessary systemic absorption. The simplest method for targeting of drugs to the colon is to obtain slower release rates or longer release periods by the application of thicker layers of conventional enteric coatings or extremely slow releasing matrices. Various pharmaceutical approaches to to colon targeted delivery system are a) covalent linkage of drug with carrier b) coating with polymers c) coating with pH sensitive polymers d) coating with biodegradable polymers. Colon targeted drug delivery system is of special importance in systemic delivery of protein and peptide drugs also important when delay in drug absorption require from therapeutic point of view in the treatment of nocturnal asthma, angina etc.
Colon targeting, site specificity, colonic diseases, biodegradable polymers
