Objective: To investigate transdermal absorption characteristics of ursolic acid in Hedyotis diffusa. Method: The content of ursolic acid was determined by HPLC.Utilized skin on the back of SD rats

Franz vertical diffusion cell was adopted to investigate transdermal performance of ursolic acid

and effect of azone

eucalyptus oil

synthetic borneol

water extract and alcohol extract of H. diffusa on transdermal performance of ursolic acid was investigated. Result: Ursolic acid was difficult to penetrate the skin

it must be added to certain transdermal absorption enhancer.Effect of enhancers on ursolic acid was in order of 5% ethanol extract>5% ethanol extract+2% borneol>5% water extract>2% azone+10% PG>2% eucalyptus oil>4% azone>3% eucalyptus oil>2% azone>1% azone. Conclusion: Azone and eucalyptus oil was good penetration enhancers for ursolic acid in H. diffusa

compound water extract and ethanol extract had a collaborative effect in promoting penetration.