Peas starch : ethylcellulose-based film coatings are proposed allowing for site-specific drug delivery to the colon of inflammatory bowel disease patients. The film coatings are poorly permeable for 5-aminosalicylic acid in media simulating the contents of the stomach and small intestine. Thus, they can minimize premature drug release in the upper gastrointestinal tract and subsequent absorption into the blood stream. However, once the colon is reached, drug release sets on and is time controlled. This can be attributed to the partial degradation of the peas starch by enzymes secreted by bacteria, which are preferentially present in the colon. Thus, the drug is released at the site of action, which is likely to minimize undesired side effects in the healthy part of the human body and to optimize the therapeutic efficacy of the treatment. A blend ratio of 1 : 4 peas starch : ethylcellulose and a coating level of 15% (w/w) seem to be optimal for pellet coating. Importantly, the polymeric films can be expected to withstand the mechanical stress encountered in vivo because of the motility of the stomach and small intestine. Furthermore, the systems are long-term stable: drug release from coated pellets remains unaltered during 1-year open storage. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 1176-1184, 2011