Abstract: AIM: To establish an LC-MS/MS method to determine the concentration of ambrisentan in human plasma and apply it to the study of human pharmacokinetics.  METHODS: After extracting ambrisentan and internal standard from human plasma by liquid-liquid extraction, chromatographic separation was performed on a Waters Symmetry C18 column (4.6 mm×100 mm, 5 μm), organic phase: 40%methanol-60%acetonitrile, water phase: 5 mmol/L ammonium acetate-10% acetonitrile, flow rate: 0.5 mL/min, electrospray ionization source, multi-reaction monitoring, negative ion mode, monitoring ion pairs of ambrisentan and internal standard are m/z 377.1→301.2 and m/z 380.4→301.0, respectively. RESULTS: The linearity of ambrisentan was good in the concentration range of 2-2 000 ng/mL, the lower limit of quantification was 2 ng/mL, the intra-day precision was less than 2.72%, the inter-day precision was less than 8.98%, the matrix effect after normalization by internal standard was between 92.3% and 98.3%, and the extraction recoveries were between 74.6% and 80.5%. CONCLUSION: This method is sensitive, economical, and reliable. It is suitable for the determination of the concentration of ambrisentan in human plasma and meets the requirements of human pharmacokinetic studies.

Key words: LC-MS/MS, ambrisentan,  , human plasma, pharmacokinetics