Simultaneous quantification of mycophenolic acid and its glucuronide metabolites in human plasma by an UPLC-MS/MS assay

The aim of this study was to develop a reliable UPLC-MS/MS assay for accurate quantification of mycophenolic acid (MPA) and its glucuronide conjugates in human plasma. Plasma proteins were precipitated with acetonitrile and the chromatographic separation was achieved on a C-18 column with a gradient elution. The detection was performed by a triple quadrupole mass spectrometer in the positive electrospray ionization and multiple reaction monitoring mode. Linearity of the assay was demonstrated over the range of 20-10,000ng/mL for MPA and MPA glucuronide (MPAG), and 2-1000ng/mL for acyl MPA glucuronide in human plasma. The assay was precise and accurate with coefficient of variation and bias <15%. MPA and MPAG were stable at 25 degrees C up to 1day in both heparin- and EDTA-treated blood. In heparin- and EDTA-plasma, MPA and MPAG were stable for at least 1week at 25 and 4 degrees C, and 1month at -20 degrees C. However, 99% acyl MPA glucuronide degraded in both heparin- and EDTA-blood as well as plasma when stored at room temperature for 1day. All the analytes remained stable for at least 3months in acidified EDTA-plasma at -80 degrees C. The assay was successfully applied on patients post hematopoietic stem cell transplantation. Copyright (c) 2016 John Wiley & Sons, Ltd.