[Development and characterization of water soluble dextran fatty acid esters as excipients for colon-targeting]

In this paper production methods of certain colon-degradable dextran fatty acid esters and their relevant properties as excipients for colon-targeting dosage forms are reported. Such dextran fatty acid esters must be insoluble in, resp. resistant against, gastric and small intestinal fluids. But to a certain degree they must be swellable in aqueous liquids in order to allow an enzymatic attack of the colonic microflora. Furthermore, they must be adequately soluble in pharmaceutically accepted solvents to permit the technological application of film coatings. Otherwise, they can only be used as embedding excipients or matrices. As the most suitable excipients for film coatings, biodegradable by the colonic microflora, but resistant against gastric and small intestinal fluids, the dextran lauroyl esters were found. Their molecular weight have to be between 60,000 and 250,000, and their average degree of substitution (DS) between 0.06 and 0.2. Are the molecular weights higher the DS must be correspondingly lower.