ALPHA,BETA-POLY(N-HYDROXYETHYL)-DL-ASPARTAMIDE HYDROGELS AS DRUG-DELIVERY DEVICES

alpha, beta-poly(N-hydroxyethyl)-DL-aspartamide (PHEA) was exposed to gamma radiation to obtain micromatrices able to swell in an aqueous me dium. Crosslinked PHEA was loaded with an anti-inflammatory drug, 4-bi phenylacetic acid (BPAA) and the drug dispersion in the network was in vestigated by X-ray analysis. The BPAA loaded PHEA microparticles were also characterized by dimensional analysis, which showed the presence of quasi-spherical shapes. The drug release from PHEA hydrogel was st udied in vitro in a pH 1.1 (simulated gastric juice) and in a pH 7.4 b uffer solution, respectively. The experimental data indicate that an a nomalous delivery occurs, but Fickian diffusion through swollen PHEA h ydrogel seems to be the predominant release mechanism. The interaction s between PHEA microparticles and dimyristoilphosphatidylcholine (DMPC ) liposomes, chosen as biomembrane model, were studied by a differenti al scanning calorimetry (DSC) technique. The calorimetric results show that the cross-linked PHEA network does not interact with the DMPC li posomes.