Inclusion of MPA and in a rapid multi-drug LC–tandem mass spectrometric method for simultaneous determination of immunosuppressants

BackroundMycophenolic Acid (MPA) is often co-prescribed as part of a multiple immunosuppressant drug regimen. In this study an established LC–MS/MS method for the measurement of immunosuppressants cyclosporine A, tacrolimus, sirolimus and everolimus was optimized to include MPA without changing the sample pre-treatment and the LC–MS/MS configuration.MethodsThe sample pretreatment for EDTA–plasma was used as for whole blood. After protein precipitation of 50 μl EDTA–plasma fast on-line matrix clean-up was performed using a column switching program. The chromatographic step was optimized to separate MPA and its glucuronide metabolite (MPAG). Multiple reaction monitoring (MRM) was used for detection of MPA (337.7 > 207.2) and MPAG (513.6 > 207.2).ResultsA total analysis time of 5 min was needed to separate MPA and MPAG. The method was linear between 0.05 and 50 mg/L for MPA. Analytical recoveries were > 95%. Variation coefficients ranged between 3.1 and 4.1%. Method comparison for MPA was performed using a commercial HPLC–UV test. The Pearson correlation coefficients were > 0.9. The Bland–Altman plot showed an excellent agreement between LC–MS/MS and HPLC–UV quantification.ConclusionWe present a robust online SPE-LC–MS/MS platform for a simultaneous and fast daily therapeutic drug monitoring of five immunosuppressive drugs in whole blood and plasma samples.