New hydrogel matrices containing an anti-inflammatory agent. Evaluation ofin vitro release and photoprotective activity

In the present work, the preparation and characterization of hydrogels base d on alpha,beta -polyaspartylhydrazide (PAHy) chemically crosslinked with e thyleneglycol diglycidylether (EGDGE) containing Tolmetin sodium salt, are reported. In particular, these samples have been prepared both as water swe llable microparticles and as gels at two different crosslinking degrees. Th e incorporation of Tolmetin sodium salt in PAHy-EGDGE microparticles has be en performed after the crosslinking reaction by a soaking procedure or duri ng the formation of the network. The influence of drug loading procedure on Tolmetin release has been evaluated by performing in vitro release study i n simulated gastrointestinal fluids (pH 1.0/6.8) using the pH variation met hod and in phosphate buffered saline, pH 7.4. PAHy-EGDGE networks containin g Tolmetin sodium salt have been also prepared as gels. These have showed a slowed down release as evidenced by in vitro release studies at pH 5.0 and 7.4 using a Franz diffusion cell system and an artificial membrane. Finall y, PAHy-EGDGE networks provide a pronounced reduction of the photosensitizi ng activity of Tolmetin, as evidenced by in vitro hemolysis assays. (C) 200 1 Elsevier Science Ltd. All rights reserved.