Objective: To study the skin local pharmacokinetics of Sinomenine Patch. Method: The microdialysis technology was used as sampling tool combined with isotope tracer method. The HPLC-UV detector and liquid scintillation counter was selected as detection tool. The relative loss(RL) was determined by using delivery method. The liner probes were implanted into the subcutaneous tissue to determine the real-time

in vivo concentration of sinomenine. The skin microdialysis sample was calibrated by relative loss and fitted with compartment and non-compartment model. Result: The compartmennt model was not the good model. The non-compartment parameters showed that the maximum skin concentration appeared at about 6 h after drug administration and the mean residence time (MRT) was about 18 h. Conclusion: The microdialysis technology could collecte the local skin pharmacokinetics characteristics of transdermal administration and of sinomenine was the appropriate study tool.