Objective: To investigate different plasma protein binding rates of pulsatilla saponin D. Method: HPLC and equilibrium dialysis method were adopted to determine plasma protein binding rates of pulsatilla saponin D in bovine serum

human and rat plasma

COSMOSIL 5C18-MS-Ⅱ column(4.6 mm×250 mm

5 μm) was employed with mobile phase of methanol-water-formic acid(80:20:0.02) and detection wavelength at 203 nm. Result: Plasma protein binding rates of pulsatilla saponin D at three various concentrations (0.06

0.11

0.25 g·L-1) were (78.45±0.89)%

(77.61±1.14)%

(77.16±0.29)% in bovine serum albumin

they were (68.91±0.54)%

(67.68±0.87)%

(67.88±0.71)% in human plasma and (78.15±0.76)%

(78.61±0.97)%

(78.24±0.93)% in rat plasma

respectively. Conclusion: This method for determining plasma protein binding rates of pulsatilla saponin D was simple

stable and reliable.Pulsatilla saponin D was a drug with moderate plasma protein binding rate

which did not have concentration-dependent manner.