Simultaneous determination of tetrahydropalmatine and imperatorin in plasma of dog by LC-MS/MS method and pharmacokinetic study on application of Yuanhu Zhitong Tablets / 中草药

ABSTRACT

Objective: To describe the pharmacokinetic profile of Yuanhu Zhitong Tablet (YZT) when administered to Beagle's dogs, a simple and sensitive method for determining tetrahydropalmatine and imperatorin in plasma of dogs was developed and validated by liquid chromatography tandem mass spectrometry (LC-MS/MS). Methods: Plasma samples were treated by a liquid-liquid extraction method with methyl tertiary butyl ether. Etofesalamide was used as internal standard (IS). The separation was performed on a ZORBAX Eclipse XDB-C18 column (50 mm × 4.6 mm, 5 μm) at 40 ℃ with a flow rate of 0.4 mL/min using gradient mobile phase. The mobile phase was consisted with methanol and 0.1% formic acid in water. After separated by liquid chromatography, analytes and IS were detected in electrospray ionization source (ESI) positive ion mode at the specific multiple reaction monitoring (MRM) transitions of m/z 356.2 [M + H]+→m/z 192.1 for tetrahydropalmatine, m/z 271.1 [M + H]+→m/z 203.0 for imperatorin, and m/z 258.1 [M + H]+→m/z 121.1 for IS. The pharmacokinetic parameters for tetrahydropalmatine and imperatorin were calculated by WinNonlin 6.3 pharmacokinetic program using non-compartmental analysis. Results: Good linearity was achieved over the concentration ranges of 0.05-20 ng/mL for tetrahydropalmatine and 0.005-2 ng/mL for imperatorin, with the lower quantification limit of 0.05 and 0.005 ng/mL, respectively. The intra-and inter-batch precisions were less than 14.4%, and the accuracies were within ± 7.19% for all analytes. The mean extraction recoveries of analytes were between 88.2%-107%, and the matrix effects of analytes were between 82.2%-108%. The pharmacokinetic parameters of tetrahydropalmatine after ig administration of YZT including tmax, Cmax, AUC0~t, AUC0~∞, MRT0~t, MRT0~∞, Vd, CL, and t1/2 were as follows (1.08 ± 0.20) h, (48.70 ±18.10) ng/mL, (170.00 ± 75.70) h·ng/mL, (178.00 ± 77.50) h·ng/mL, (6.41 ± 1.13) h, (8.09 ± 1.85) h, (133.00 ± 63.00) L, (11.90 ± 5.54) L/h, and (7.71 ± 1.07) h; The pharmacokinetic parameters of imperatorin were (1.17 ± 0.26) h, (0.063 4 ± 0.023 5) ng/mL, (0.1760 ± 0.091 9) h·ng/mL, (0.204 0 ± 0.097 3) h·ng/mL, (2.550 ± 0.669) h, (3.640 ± 0.818) h, (22 351 ± 7 990) L, (7 917 ± 6 030) L/h, and (2.390 ± 0.877) h. Conclusion: The fully validated LC-MS/MS method is successfully applied to a pharmacokinetic study on tetrahydropalmatine and imperatorin in Beagle's dogs following ig administration of YZT.