PREPARATION, STRUCTURE AND DIFFUSIONAL BEHAVIOR OF HYDROGELS IN CONTROLLED-RELEASE

The release of drugs, peptides and proteins from hydrogels is controlled by the macromolecular structure of the carrier as defined by the degree of crosslinking, the degree of swelling and related parameters. Ionic interactions play an important role in drug transport. For swelling-controlled systems, the coupling of diffusion and macromolecular relaxation control the mechanism of drug release, providing conditions of zero-order release. Application of such systems in various delivery situations is discussed with emphasis on the delivery rate and the stability of the releasing bioactive agents.