2020 Volume 69 Issue 1 Pages 36-43
Mycophenolate mofetil (MMF), a mycophenolic acid (MPA) prodrug, has been commonly used in immunosuppressive therapy after organ transplantation. Since the pharmacokinetics of MPA has a large interindividual variability, therapeutic drug monitoring (TDM) is needed. MPA concentration has been measured by liquid chromatography tandem mass spectrometry (LC-MS/MS) or the enzyme-multiplied immunoassay technique (EMIT). However, the LC-MS/MS method is complicated and needs many hours; on the other hand, EMIT detects both MPA and its metabolites. In this study, we examined the performance of the particle-enhanced turbidimetric inhibition immunoassay (PETINIA) for the measurement of MPA in terms of its within-run and day-to-day run reproducibilities, linearity, and detection limits, and the effects of interfering substances, serum-separating agents, storage condition, as well as wide-range relationship with LC-MS/MS. PETINIA showed a satisfactory performance in terms of sensitivity, reproducibility, and specificity. In addition, serum-separating agents did not affect the concentration measurements, and the storage stability was equivalent to the data described in the attached document of the reagent. The correlation with the LC-MS/MS method was satisfactory (y = 1.18x − 0.09, r = 0.980, p < 0.01), but plasma samples more than 15 μg/mL MPA showed higher MPA concentrations in PETINIA. In conclusion, the clinical usefulness of PETINIA for the measurement of plasma MPA concentrations was suggested in the lower range; on the other hand, the higher plasma MPA concentrations measured by PETINIA should be carefully interpreted.
