Effects of penetration enhancers on Shuangwu traumatic formula: In vitro percutaneous absorption and in vivo pharmacodynamic evaluation of an herb medicine

The purposes of this study were to improve the transdermal permeation of the Shangwu traumatic formula by chemical penetration enhancers and to investigate the pharmacodynamic changes of the formula caused by incorporated enhancers. The effects of different enhancers on the transdermal absorption of piperine, the representative component of formula, were investigated by in vitro permeation studies. The tests showed an increasing enhancement effect in the following order: Azone/N-methylpyrrolidone (NMP) > oleic acid > Azone/peppermint oil > Azone/oleic acid > Azone/propylene glycol > Azone > peppermint oil > NMP > propylene glycol. The ratio and the content of the most effective enhancer Azone/NMP were determined subsequently. The results suggested that the most significant penetration enhancement was achieved by 3% (w/w) Azone/NMP (3:7). Furthermore, the in vivo pharmacodynamic responses of the formula suspension with or without Azone/NMP were compared using hot-plate assay and xylene-induced ears edema test as models. The data indicated that the formula had positive effect on analgesis and anti-inflammatory, which can be enhanced with the addition of enhancers.