Novel nanostructured supramolecular hydrogels for the topical delivery of anionic drugs.

A bis-imidazolium-based amphiphilic molecule was used to form novel supramolecular gels in ethanol-water mixtures. The proportion of solvents, the concentration of gellant and the temperature are factors that strongly influence the gelling process. The physical gels that are formed comprise entangled fibers of around 100nm in diameter, able to incorporate anionic drugs, whose morphology varies depending on the drug they incorporate. These hydrogels are soft and therefore optimum for skin application. They show good stability when compared to previously reported gels. Suitable drug release and skin permeation profiles were obtained, and, moreover, they seem to promote the retention of the drug inside the skin. Finally, effective in vivo anti-inflammatory activity was observed, especially with the indomethacin-incorporated gel, which indicates that these supramolecular hydrogels are a good option for the delivery of poor water soluble drugs for the treatment of acute inflammation or other skin diseases.