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. Dextran hydrogels exhibited degradation in vitro by a dextranase preparation and in vivo in the rat caecum. Enzymatic degradation of the hydrogels by dextranase appeared to proceed by surface erosion, and the degradability of dextran hydrogels was found to be easily controlled by changing their chemical structure. The network parameters v(e) (effective crosslinking density) and 1/v(2) (hydration) were determinants for degradability. A decrease in cross-linking density or an increase irt degree of hydration of the hydrogels afforded a higher enzymatic degradation rare. Furthermore, the concentration of dextranase in the degradation solution was important for the dissolution time (tau) of the dextran hydrogels.