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

Backround: Mycophenolic 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. Methods: The sample pretreatment for EDTA-plasma was used as for whole blood. After protein precipitation of 50 mu l 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). Results: A 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. Conclusion: We 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. (c) 2006 Elsevier B.V. All rights reserved.