DRUG-RELEASE FROM HYDROGELS OF CROSS-LINKED POLYETHYLENE OXIDE

By irradiation (gamma-rays) of aqueous polyethylene oxide solutions containing drugs with different chemical structures and pharmacological activity, drug loaded crosslinked hydrogel systems were obtained. Only with poorly water soluble drugs and drugs with sulfur atoms were no stable hydrogels formed. By UV-spectroscopic investigations, it can be shown that most of the model drugs involved in this study remained unchanged after irridation. The incorporation of the drugs before crosslinking provides a homogeneous distribution within the hydrogel and a slow in vitro release over more than 8 h. The release kinetics can be characterized as a non-Fickian diffusion (release exponent n = 0.54 to 0.58). The incorporation of the drugs into previously prepared cross-linked hydrogels leads to a very fast in vitro drug release. Within 2 h more than 90% of each drug wos released.