Amylose formulations for drug delivery to the colon: a comparison of two fermentation models to assess colonic targeting performance in vitro

The purpose of this study was to develop an enzyme-based fermentation system for the in vitro assessment of colonic digestion of amylose films and coatings, and to compare its performance with a conventional fermentation model inoculated with human faecal bacteria. Amylose and ethylcellulose were mixed in different ratios and cast as isolated films, as well as spray coated onto drug-(5-aminosalicylic acid) loaded pellets. Four commercial amylase enzymes were individually screened for their ability to digest amylose cast films. The enzyme from the bacterium Bacillus ficheniformis was found to be the most active against this substrate. Digestion of mixed amylose and ethylcellulose films was also observed, with the extent of digestion being proportional to the quantity of amylose present in the film. In terms of product performance, drug release from coated pellets was accelerated in the presence of the enzyme. The results with the enzyme system were comparable to those obtained from a faecal-based fermentation model, thereby suggesting that such a system has practical potential for in vitro screening of putative amylose formulations for colonic drug delivery. (C) 2004 Elsevier B.V. All rights reserved.