Sensitive method for the determination of paricalcitol by liquid chromatography and mass spectrometry and its application to a clinical pharmacokinetic study

A highly sensitive, specific and rapid LC‐ESI‐MS/MS method has been developed and validated for the quantification of paricalcitol (PAR) in human plasma (500 μL) using paricalcitol‐d6 (PAR‐d6) as an internal standard (IS) as per regulatory guidelines. A liquid–liquid extraction method was used to extract the analyte and IS from human plasma. Chromatography was achieved on Zorbax SB C18 column using an isocratic mobile phase in a gradient flow. The total chromatographic run time was 6.0 min and the elution of PAR and PAR‐d6 occurred at ~2.6 min. A linear response function was established for the range of concentrations 10–500 pg/mL in human plasma. The intra‐ and inter‐day accuracy and precision values for PAR met the acceptance criteria. The validated assay was applied to quantitate PAR concentrations in human plasma following oral administration of 4 µg capsules to humans. Copyright © 2014 John Wiley & Sons, Ltd.