Colon targeted drug delivery

Colon-specific drug delivery systems (CDDS) are desirable for the treatment of a range of local diseases such as ulcerative colitis, Crohn’s disease, irritable bowel syndrome, chronic pancreatitis, and colonic cancer. In addition, the colon can be a potential site for the systemic absorption of several drugs to treat non-colonic conditions. Drugs such as proteins and peptides that are known to degrade in the extreme gastric pH, if delivered to the colon intact, can be systemically absorbed by colonic mucosa. In order to achieve effective therapeutic outcomes, it is imperative that the designed delivery system specifically targets the drugs into the colon. Several formulation approaches have been explored in the development colon-targeted drug delivery systems. Colon targeting holds a great potential and still need more innovative work. This review article discusses introduction of colon, need and approaches of colonic drug delivery, factor effecting colonic transition, colonic diseases and the novel and emerging technologies for colon targeting.

The colon is the terminal part of the GIT which has gained increased importance not just for the delivery of the drugs for both local and systemic administration. The delivery of drug for the treatment of local diseases associated with the colon like Crohn’s disease, ulcerative colitis, etc. but also for the systemic delivery of proteins, therapeutic peptides, anti-asthmatic drugs, antihypertensive drugs and anti-diabetic agents. To achieve successful colon targeted drug delivery, a drug need to be protected from degradation, release and absorption in the upper portion of the GI tract and then to be ensured abrupt or controlled release in the proximal colon and that system refers to delivery of drug in to lower part of the GI tract, mainly large intestine. When this is the most important delivery of those drug which are normally inactivated in the upper parts of the gastrointestinal tract (GIT). This review mainly compares the primary approaches for CDDS (Colon Specific Drug Delivery) namely prodrugs, pH and time dependent systems, and microbial 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 (ORDS-CT) which are unique in terms of achieving the in vivo site specificity, and feasibility of manufacturing process for the CDDS. These treatments could be more effective if it is possible for drug to be directly delivered to colon. This review article discusses introduction of colon, need and approaches of colonic drug delivery, factor effecting colonic transition, colonic diseases and the novel and emerging technologies for advanced colon targeting for site specific drug delivery to colon. It is a challenging area for future research and holds lots of promises for novel and efficient approach for targeted drug delivery system.

The potential of guar gum as a film coating material for colon targeted delivery of raupyabhasma is assessed in this study. The granules was prepared by mixing raupyabhasma, guar gum and xanthan gum which was coated by guar gum and pH-sensitive polymer eudragit FS30D sequentially around drug-loaded granules. The outer eudragit FS30D coating defends the system against gastrointestinal environment and dissolves rapidly in distal small intestine, where a lumen pH of over 7 triggers the dissolution of the enteric polymer. The inner guar gum coating works as a time-controlled retardant and offers additional protection of the granules until it is degraded by microbes at the proximal colon. In vitro results indicate that guar gum followed by eudragit FS30D coating is a feasible coating material to achieve colon specific drug delivery.