Delivery of Potential Drugs to The Colon: Challenges and Strategies

Colon-targeted drug delivery systems have been exploited to treat local diseases in the colon, systemic delivery of protein and peptide, and chronotherapeutic drugs. However, the upper gastrointestinal tract restricts the effective delivery. Therefore, several strategies are needed for drugs targeted directly to the colon, such as pH-sensitive and enzyme-sensitive polymers, bacterially degradable polysaccharides, time-dependent polymers, as well as particulate systems. Variable physiological conditions of the gastrointestinal tract in individuals cause the combinations of these strategies to ensure colonic delivery of drugs. This review presents and discusses several potential drugs and the approaches used to design and develop colon-targeted drug delivery systems for medications with particular characteristics.