Objective: To investigate the effects of water soluble azone as an additive in Shengfaling tincture on transdermal absorption of ferulic acid and determine the optimum concentration to promote the absorption.
Method: Using a two-chamber diffusion cell, the amounts of ferulic acid that had permeated in vitro rat skin was determined by high-performance liquid chromatography at different time points after shengfaling tincture containing different concentrations of water-soluble azone was applied on the skin.
Results: When shengfaling tincture contained 1.509% water-soluble azone, the maximum total release of ferulic acid (2 356.7 microgram) was achieved with the maximum release rate of 242.9 microgram/cm(2).h(-1).
Conclusion: Water-soluble azone can promote the transdermal absorption of ferulic acid in Shengfaling tincture with the optimal concentration of 1.509%.