Rapid determination of fenoldopam in human plasma by UPLC–MS/MS for pharmacokinetic analysis in patients

•We developed a rapid UPLC–MS/MS method for quantifying fenoldopam in human plasma.•The matrix effect and stability of fenoldopam in hemolyzed plasma was evaluated.•The method was successfully applied to the pharmacokinetic analysis of fenoldopam in the plasma of hypertensive patients. We developed and validated a rapid, selective, and sensitive ultra-performance liquid-chromatography mass-spectrometry (UPLC–MS/MS) method for quantifying fenoldopam in human plasma for pharmacokinetic studies. Fenoldopam and the internal-standard (IS), oxazepam, were isolated from human plasma by liquid–liquid extraction using ethyl acetate after alkalization, and were separated on a 2.1×100mm Acquity UPLC HSS T3 C18 column (inside diameter, 1.8μm) using a mobile phase of water (0.05% formic acid) and acetonitrile gradient elution. The fenoldopam and IS were eluted at 1.07 and 2.32min, respectively. Quantification was performed using positive-ion electrospray-ionization (ESI), and the fenoldopam and IS responses were optimized at the m/z 306.16→107.10 and m/z 287.1→241.01 transitions, respectively. The assay was validated over the linear range of 0.1–40ng/mL fenoldopam with intra- and interassay precision