Determination of 25-OH-PPD in rat plasma by high-performance liquid chromatography–mass spectrometry and its application in rat pharmacokinetic studies

A sensitive and specific liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed for the investigation of the pharmacokinetics of 20(R)-dammarane-3β,12β,20,25-tetrol (25-OH-PPD) in rat. Ginsenoside Rh2 was employed as an internal standard. The plasma samples were pretreated by liquid–liquid extraction and analyzed using LC/MS/MS with an electrospray ionization interface. The mobile phase consisted of methanol–acetonitrile–10 mmol/l aqueous ammonium acetate (42.5:42.5:15, v:v:v), which was pumped at 0.4 ml/min. The analytical column (50 mm × 2.1 mm i.d.) was packed with Venusil XBP C8 material (3.5 μm). The standard curve was linear from 10 to 3000 ng/ml. The assay was specific, accurate (accuracy between −1.19 and 2.57% for all quality control samples), precise and reproducible (within- and between-day precisions measured as relative standard deviation were <5% and <7%, respectively). 25-OH-PPD in rat plasma was stable over three freeze–thaw cycles and at ambient temperatures for 6 h. The method had a lower limit of quantitation of 10 ng/ml, which offered a satisfactory sensitivity for the determination of (25-OH-PPD) in plasma. This quantitation method was successfully applied to pharmacokinetic studies of 25-OH-PPD after both an oral and an intravenous administration to rats and the absolute bioavailability is 64.8 ± 14.3%.