ObJective: To determine the concentration of sinomenine and triptolide in nude mouse hypodermis. Method: Microdialysis coupled with high-performance liquid chromatography was developed for on-line determination of the in vivo concentration of sample

when the perfusate was 30% ethanol/physiological saline solution.The Diamonsil-C18 column (4.6 mm×250 mm

5 μm)was used and the mobile phase consisted of methanol ∶buffer phosphate(pH 9.0)(55 ∶45).The detect wave length was 225 nm.The data obtained after being calculated using the relative recovery in vivo were dealed with WINNONLIN 5.2 programe

while retro-dialysis method was used to study relative recovery in vivo . Result: The peak time of sinomenine and triptolide were 14 h and 10 h

peak concentrations were 30.15 μg ·mL-1 and 3.31 μg ·mL-1 respectively. Conclusion: The method can be used to determine in vivo and real time concentration of sinomenine and triptolide in the skin dynamically. It is suitable for the pharmacokinetics study of sinomenine and triptolide at the same time.