Diclofenac-hydrotalcite: In vitro and in vivo release experiments

Solutions of the anti-inflammatory drug diclofenac in ethanol and ethanol–water were prepared and mixed with hydrotalcite and hydrotalcite heated at 500 °C. Hydrotalcite pretreated at 500 °C showed a higher adsorption of diclofenac. Diclofenac-hydrotalcites were used for in vitro release experiments to evaluate the percutaneous absorption of diclofenac, using sets of eight Franz cells with membranes of stratum corneum epidermis obtained from human skin; a 2% diclofenac hydroalcoholic gel was used for comparison. Hydrotalcite pretreated at 500 °C is less suitable for release procedures, despite its higher adsorption capacity, whereas diclofenac adsorbed from ethanolic solution by untreated hydrotalcite presents the most efficient sample and shows the best permeation profiles. This sample was selected for the in vivo experiments. Ten healthy volunteers participated on the in vivo experiments: the diclofenac-hydrotalcite appeared to be useful for an efficient application on human skin as inhibitor of the UV-induced erythemas, also better than the usual gel samples.