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 2.1×100 mm Acquity UPLC HSS T3 C18 column (inside diameter, 1.8 μm) using a mobile phase of water (0.05% formic acid) and acetonitrile gradient elution. The fenoldopam and IS were eluted at 1.07 and 2.32 min, 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 0.1-40 ng/mL fenoldopam with intra- and interassay precision <13.21%. The matrix effect of normal and hemolyzed plasma was 94.9-101.6%. Fenoldopam was stable for ≥34 days at -70 °C in normal and hemolyzed plasma containing ascorbic acid as a stabilizer. This method can be successfully applied in pharmacokinetic studies of fenoldopam in hypertensive patients.
Keywords: Fenoldopam; Hemolyzed plasma; Human plasma; Pharmacokinetics; UPLC–MS/MS.
Copyright © 2014 Elsevier B.V. All rights reserved.