Objective: To study effect of azone on transdermal absorption in vitro of Ruyijinhuang cream. Method: Modified Franz diffusion cell was used

selected rat abdominal skin as permeability barriers

the content of chrysophanol in samples was determined by HPLC

effect of concentrations of azone on transdermal absorption of Ruyijinhuang cream were compared. Cumulative percentage of permeation at different time period was attained

and calculated penetration rate constant. Result: Penetration rate constants of Ruyijinhuang cream samples were 0.006 06

0.009 47

0.018 74

0.019 18

0.015 05 μg·cm-2·h-1 respectively corresponding to the concentrations of azone at 0

1%

2%

3%

4%. Conclusion: Azone could be chosen as transdermal enhancer of Ruyijinhuang cream with the concentration of 3%.