Novel polymeric film coatings for colon targeting: how to adjust desired membrane properties

The major aim of this work was to optimize the properties of novel polymeric films based on blends of ethylcellulose and Nutriose (a water-soluble, branched dextrin). Such blends were recently shown to be highly promising for the site-specific delivery of drugs to the colon in patients suffering from inflammatory bowel diseases, in particular Crohn's disease and ulcerative colitis. Importantly, and in contrast to various other colon targeting approaches, the system is adapted to the pathophysiological conditions in the disease state. However, it is yet unknown how desired membrane properties, especially water uptake and dry mass loss kinetics as well as mechanical stability can be adjusted to the specific needs of particular drug treatments. Different highly efficient and easy to apply tools were identified altering the membrane's properties, in particular their mechanical resistance required to withstand the shear forces resulting from the motility of the upper GIT and the hydrostatic pressure built up within the devices upon contact with aqueous media. This includes the variation of the Nutriose:ethylcellulose blend ratio and initial plasticizer content. Importantly, Nutriose also exhibits significant pre-biotic activity, normalizing the microflora in the patients' colon, which is of major clinical benefit in the case of inflammatory bowel diseases.