DEXTRAN HYDROGELS FOR COLON-SPECIFIC DRUG-DELIVERY .3. IN-VITRO AND IN-VIVO DEGRADATION

In the present study, the degradation of dextran hydrogels, potential drug carriers for colon-specific drug delivery, was investigated. Dext ran hydrogels exhibited degradation in vitro by a dextranase preparati on and in vivo in the rat caecum. Enzymatic degradation of the hydroge ls by dextranase appeared to proceed by surface erosion, and the degra dability of dextran hydrogels was found to be easily controlled by cha nging their chemical structure. The network parameters v(e) (effective crosslinking density) and 1/v(2) (hydration) were determinants for de gradability. A decrease in cross-linking density or an increase irt de gree of hydration of the hydrogels afforded a higher enzymatic degrada tion rare. Furthermore, the concentration of dextranase in the degrada tion solution was important for the dissolution time (tau) of the dext ran hydrogels.