Peas Starch-Based Film Coatings for Site-Specific Drug Delivery to the Colon

Received 30 January 2010; accepted 9 May 2010DOI 10.1002/app.32802Published online 30 July 2010 in Wiley Online Library (wileyonlinelibrary.com).ABSTRACT: Peas starch : ethylcellulose-based film coat-ings are proposed allowing for site-specific drug delivery tothe colon of inflammatory bowel disease patients. The filmcoatings are poorly permeable for 5-aminosalicylic acid inmedia simulating the contents of the stomach and smallintestine. Thus, they can minimize premature drug releasein the upper gastrointestinal tract and subsequent absorp-tion into the blood stream. However, once the colon isreached, drug release sets on and is time controlled. Thiscan be attributed to the partial degradation of the peasstarch by enzymes secreted by bacteria, which are preferen-tially present in the colon. Thus, the drug is released at thesite of action, which is likely to minimize undesired sideeffects in the healthy part of the human body and to opti-mize the therapeutic efficacy of the treatment. A blend ratioof 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 me-chanical stress encountered in vivo because of the motility ofthe stomach and small intestine. Furthermore, the systemsare long-term stable: drug release from coated pelletsremains unaltered during 1-year open storage.