Simultaneous Determination of Six Alkaloids in Rat Plasma by SPE-HPLC-MS/MS and Their Pharmacokinetics after Oral Administration of Radix aconiti Preparata Extract

Simultaneous determination of the content of six alkaloids (aconitine, hypoaconitine, mesaconitine, benzoylaconine, benzoylhypaconine, and benzoylmesaconine) in rat plasma is enabled by HPLC-MS/MS combined with microsolid phase extraction (micro-SPE). To study its pharmacokinetics in rat plasma, the extracted plasma sample was passed through a C18 extraction column and eluted with acetonitrile. The six alkaloids in the Radix aconiti Preparata extract can be completely separated as peaks with good shape. The six components in the plasma sample showed a good linear relationship within their respective linear ranges (R-2 > 0.997). The analysis of the six alkaloids can be completed within 20 min. This method has high intraday and interday precision, and the room temperature stability and freeze-thaw stability are good. The matrix effect of the plasma samples is between 86.4 and 114%. The metabolism of the six Aconitum alkaloids in plasma is analyzed using a two-compartment model, which is characterized by fast absorption, slow elimination, and good linear fit, R-2 > 0.99. The peak time (T-max) for aconitine, hypaconitine, and neoaconitine ranged from 29.95 to 42.07 min, while the peak time (T-max) for benzoaconitine, benzohypaconitine, and benzoxinaconitine ranged from 42.88 to 73.08 min. With the increased dosage, the bioavailability of Aconitum alkaloids decreased gradually. The method for the determination of Aconitum alkaloids in rat plasma by high performance liquid chromatography-tandem mass spectrometry is sensitive and accurate, which is suitable for rat plasma analysis. The results provide a scientific basis for metabolic study of Aconitum alkaloids in vivo, and pave the way for clinical use of Aconitum medicinal materials and extracts.