Formulation of microemulsion systems for transdermal delivery of aceclofenac

An O/W microemulsion system was developed to enhance the skin permeability of aceclofenac. Of the oils studied, Labrafil® M 1944 CS was chosen as the oil phase of the microemulson, as it showed a good solubilizing capacity. Pseudo-ternary phase diagrams were constructed to obtain the concentration range of oil, surfactant, Cremophor® ELP, and co-surfactant, ethanol, for micoemulsion formation. Eight different formulations with various values of oil of 6–30%, water of 0–80%, and the mixture of surfactant and co-surfactant (at the ratio of 2) of 14–70%. Thein vitro transdermal permeability of aceclofenac from the microemulsions was evaluated using Franz diffusion cells mounted with rat skin. The level of aceclofenac permeated was analyzed by HPLC and the droplet size of the microemulsions was characterized using a Zetasizer Nano-ZS. Terpenes were added to the microemulsions at a level of 5%, and their effects on the skin permeation of aceclofenac were investigated. The mean diameters of the microemulsions ranged between approximately 10≈100 nm, and the skin permeability of the aceclofenac incorporated into the microemulsion systems was 5-fold higher than that of the ethanol vehicle. Of the various terpenes added, limonene had the best enhancing ability. These results indicate that the microemulsion system studied is a promising tool for the percutaneous delivery of aceclofenac.