New biodegradable hydrogels based on a photo-cross-linkable polyaspartamide and poly(ethylene glycol) derivatives. Release studies of an anticancer drug

 The functionalization of α,β-poly(N-2-hydroxyethyl)-dl-aspartamide (PHEA) with glycidyl methacrylate (GMA) gives rise to a water-soluble photosensitive copolymer PHEA-GMA (PHG). Aqueous solutions of PHG alone or in combination with various concentrations of poly(ethylene glycol) dimethacrylate or poly(ethylene glycol) diacrylate (PEGDA) have been exposed to a source of UV rays at 313 nm in order to obtain polymeric networks. All samples have been prepared both as water-swellable microparticles and as gel systems. Microparticles have been characterised by Fourier transform IR spectrophotometry, dimensional analysis and swelling measurements in aqueous media mimicking biological fluids. In vitro chemical and enzymatic hydrolysis studies showed that all the prepared samples undergo a partial degradation at pH 1, 7.4 and 10 as well as after incubation with enzymes such as esterase. The effect of the cross-linking density on the rheological behavior of gel systems has also been investigated. PHG/PEGDA hydrogel is able to incorporate, during UV-irradiation, 5-fluorouracil (5-FU), chosen as a model drug, and to release it in simulated biological fluids, as confirmed by in vitro drug release studies at pH 1 and 7.4. PHG/PEGDA gel containing 5-FU is able to release this drug in a prolonged way, more slowly than a commercial ointment, as confirmed by in vitro studies at pH 5.5 and 7.4 using a Franz diffusion cell system and a synthetic membrane. Received: 3 October 2000 Accepted: 13 December 2000