NOVEL POLYMERIC EXCIPIENTS FOR COLON-TARGETING

Oral drug delivery to the colon is of interest for the local treatment of colonic diseases and for the systemic delivery of drugs. Our goal is to develop coating materials that are stable in gastric and small i ntestinal fluids and degradable in the colon by bacterial polysacchari dases. For testing colon-degradability an in vitro model was developed . A number of polysaccharide derivatives were synthesized and tested: almost completely ethylated or acetylated galactomannans, polyurethane s with galactomannan sections, crosslinked galactomannans and dextrane sters of fatty acids. Generally, degradability decreased with increasi ng degree of substitution. Especially crosslinked galactomannan and de xtranesters with a low degree of substitution or crosslinking, respect ively, are promising materials. Using an industrial coating technique tablets were coated with crosslinked galactomannan and the enzymatical ly induced in vitro dissolution of a model drug was investigated.