ABSTRACT
<p><b>OBJECTIVE</b>To screen the optimum formulation and prepare O/W sinomenine microemulsion and investigate its in vitro transdermal delivery ability.</p><p><b>METHOD</b>The microemulsions were prepared with the formulation containing oleic acid-tween 80-dehydrated alcohol-water by the pseudo-ternary phase diagram. The permeation flux of sinomenine was determined in vitro by Franz diffusion cell fitted with rat skin. The sinomenine was determined by HPLC. The transdermal characteristics of sinomenine microemulsion were compared with that of sinomenine gels.</p><p><b>RESULT</b>The steady state flux of sinomenine microemulsion was significantly higher than that of sinomenine gels. The average permeation rate of sinomenine microemulsion was 116. 44 microg x cm(-2) x h(-1) in vitro.</p><p><b>CONCLUSION</b>These results indicated that the studied microemulsion system with high permeation rate may be a potential vehicle for the transdermal delivery of sinomenine.</p>