Evaluation of the in vitro release and permeation of Cordia verbenacea DC essential oil from topical dosage forms

Abstract

abstract The first fully developed herbal medicine in Brazil, Acheflan®, contains the essential oil of Cordia verbenacea DC that is present at 0.5% in both a cream and aerosol form. Its topical use is indicated for the treatment of muscle aches and tendinitis to alleviate discomfort related to associated inflammatory processes. The two principal components of the essential oil involved in the anti-inflammatory activity are α-humulene and (-)-trans-caryophyllene, which need to penetrate the skin to exert their effects. The objective of this work was to evaluate, for the first time, the in vitro release profiles and the permeation of these commercial phytotherapeutics using Franz diffusion cells. The results indicate that the commercial products have a low release profile that appears to restrict permeation of the oil components. This was in contrast to the pure essential oil, which presented a good capacity to permeate through skin. To improve release, new nanoemulsion formulations were developed and evaluated for their release profiles, permeation and kinetic parameters. The transition to a nanoemulsion system was shown to improve the permeation profiles of the essential oil as these formulations had a high in vitro permeation and release flux rate. In addition, the final formulation presented an adequate droplet distribution size, polydispersity index and pH. Overall, we observed that the composition of formulations that contain Cordia verbenacea DC can directly influence the diffusion of the oil components through dermal barriers, which can potentiate their intended anti-inflammatory effects.