RESUMEN
<p><b>OBJECTIVE</b>To study the plasma protein binding rate of methyl protodioscin.</p><p><b>METHOD</b>The ultrafiltration was employed to determine the plasma protein binding rate of methyl protodioscin. The plasma concentrations of methyl protodioscin were measured by HPLC-MS-MS.</p><p><b>RESULT</b>The plasma protein binding rate of methyl protodioscin with rat plasma at the concentration of 20.0, 100 and 200 microg x mL(-1) were (94.6 +/- 0.16)%, (91.6 +/- 0.35)% and (86.10 +/- 0.60)%, respectively, while the plasma protein binding rate of methyl protodioscin with normal human plasma at the above concentrations were (82.11 +/- 5.12)%, (84.54 +/- 0.32)% and (88.52 +/- 1.02)%, respectively.</p><p><b>CONCLUSION</b>The binding rate of methyl protodioscin with plasma protein is high.</p>