Development of a Liquid Chromatography–Tandem Mass Spectrometric Method for Quantification of Mycophenolic Acid and Its Glucuronides in Dried Blood Spot Samples
Personalized immunosuppressive therapy, including accurate drug dosing based on the drug blood level, leads to better clinical outcomes, specifically regarding avoidance of drug-induced adverse effects and maintenance of efficacy. Mycophenolic acid (MPA) is used as an immunosuppressant in transplantation of various solid organs. The aim of this study was to develop a method for quantification of MPA and its metabolites, mycophenolic acid 7-O-glucuronide (MPAG) and mycophenolic acid acyl glucuronide, in dried blood spot (DBS) samples, using liquid chromatography/electrospray ionization/tandem mass spectrometry.Methods:
For sample preparation, a microwave-drying approach was used to deactivate enzymes and reduce drying time. Blood volume was calculated in a DBS disk of 3 mm diameter. Concentrations of analytes in plasma from patients receiving mycophenolate mofetil were compared with DBS samples after hematocrit correction.Results:
The method yielded good recoveries of all 3 analytes (90.3%–104.2%). Blood volume in the disk was calculated as 3.0 ± 0.2 μL. Linearity over concentration ranges of 0.1–30 mcg/mL MPA, 0.1–200 mcg/mL MPAG, and 0.125–10 mcg/mL mycophenolic acid acyl glucuronide was obtained with r2 ≥0.999. Intraday and interday variations were less than 14.6%, and accuracy was within ±11.9%. Passing–Bablok analysis showed no significant differences between plasma concentrations and DBS concentrations after hematocrit correction of MPA and MPAG.Conclusions:
We developed and validated a liquid chromatography/electrospray ionization–tandem mass spectrometry method for analysis of MPA in DBS samples. The method is useful for monitoring the MPA blood level.