Development and validation of a high-performance liquid chromatography-tandem mass spectrometry method for the rapid simultaneous quantification of aconitine, mesaconitine, and hypaconitine in rat plasma after oral administration of Sini decoction.

A rapid, sensitive, and specific liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS) method was developed and validated for simultaneous determination of aconitine (AC), mesaconitine (MA), and hypaconitine (HA), the three toxic constituents from Sini decoction (SND) in rat plasma. After the addition of citalopram as the internal standard (IS), plasma samples were basified with 100 microL 10% ammonium hydroxide, and then extracted with 1 mL ethyl acetate. Chromatographic separation was performed on a CN column (250 mm x 4.6 mm, 5 microm) with a mobile phase of methanol/40 mM ammonium acetate/formic acid (950:45:5, v/v/v) at the flow rate of 1.0 mL/min. Analytes were determined in a triple-quadrupole mass spectrometer in the selected reaction-monitoring (SRM) mode using electrospray source with positive mode. The method was validated over the concentration ranges of 0.01-10 ng/mL for AC, MA, and HA. The variation coefficients were always < 15% for both intraday and interday precision for each analyte. Mean accuracies were also within +/-15%. The method was proved to be sensitive, rapid, specific, accurate, and reproducible. It has been successfully applied to the pharmacokinetics study on rats after oral administration of SND.

Solid-phase extraction and liquid chromatography/tandem mass spectrometry assay for the determination of pitavastatin in human plasma and urine for application to Phase I clinical pharmacokinetic studies.

A sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed and evaluated for the determination of pitavastatin in human plasma and urine. Samples were extracted using solid-phase extraction (SPE). The major benefit of the present method was the high sensitivity, with a lower limit of quantification (LLOQ) of 0.08 ng/mL. Pitavastatin and internal standard (IS, rosuvastatin) were separated on a C(18) column with a mobile phase consisted of methanol/water (75:25, v/v) with 0.05% formic acid. Drug and IS were detected by LC/MS/MS with positive electrospray ionization (ESI). Accuracy and precision for the assay were determined by calculating the intra- and inter-batch variation of quality control (QC) samples at three concentration levels, with relative standard deviations (R.S.D.s) of less than 15%. The developed method was successfully applied to determine pitavastatin in human plasma and urine, and was proved to be suitable for use in Phase I clinical pharmacokinetic study after oral administration of pitavastatin (1, 2 and 4 mg) in healthy Chinese volunteers.