Comparison of a Point-of-Care Testing with Enzyme-Multiplied Immunoassay Technique and Liquid Chromatography Combined With Tandem Mass Spectrometry Methods for Therapeutic Drug Monitoring of Mycophenolic Acid: A Preliminary Study

Abstract

Background: For mycophenolic acid (MPA), therapeutic drug monitoring is an essential tool for dosage optimization in transplant recipients and autoimmune diseases. In China, a new commercial kit using an immunochromatographic assay (FICA) with a point-of-care testing system was approved for therapeutic drug monitoring of MPA. However, corroboration between FICA and clinically used assays remains unknown. The authors evaluated MPA concentrations in heart transplant recipients obtained by FICA, highperformance liquid chromatography combined with tandem mass spectrometry (LC-MS/MS), and enzyme-multiplied immunoassay technique (EMIT).Methods: Nine heart transplant recipients administered a single mycophenolate mofetil (MMF) dose, and 4 administered multiple MMF doses were enrolled. MPA samples were collected before administration, and after 0.5, 1, 1.5, 2, 4, 6, 8, 10, and 12 hours, and assessed by 2 immunoassays (EMIT and FICA) and LC-MS/MS. Consistency between methods was evaluated using Passing-Bablok regression and Bland-Altman analysis.Results: For Passing-Bablok regression between FICA and LC-MS/MS, FICA = 0.784 LC-MS/MS + 0.360 (95% CI slope: 0.739 to 0.829, 95% CI intercept: 0.174-0.545). Regardless of a significant observed correlation coefficient (R 2 = 0.9126), statistical analyses revealed a significant difference between FICA and the reference LC-MS/MS method. The mean absolute bias was 0.69 mcg/mL between FICA and LC-MS/MS. Bland-Altman plots showed a mean bias of 20.23 mcg/mL (61.96 SD, 22.19 to 1.72 mcg/mL) and average relative bias of 14.73% (61.96 SD, 267.91% to 97.37%) between FICA and LC-MS/MS. Unsatisfactory consistency was observed between EMIT and LC-MS/MS, and FICA and EMIT. Differences between pharmacokinetic parameters after a single or 7 days of MMF administration, by LC-MS/MS and FICA, were not statistically significant. Conclusions:The consistency of the new FICA using a point-ofcare testing device with LC-MS/MS and EMIT was inadequate, and the accuracy of EMIT and LC-MS/MS was inappropriate. Clinicians should be informed when switching MPA detection methods to avoid misleading results.

Switching Between LC-ESI-MS/MS and EMIT Methods for Routine TDM of Valproic Acid in Pediatric Patients With Epilepsy: What Clinicians and Researchers Need to Know

“…To the best of our knowledge, this is the first study to compare the concentration of VPA measured by LC–ESI-MS/MS and EMIT methods with a large number of samples. The results of this study demonstrated the overestimation by routine EMIT assay compared with LC–ESI-MS/MS, which was in line with previous reports for other medications ( Prémaud et al, 2004 ; Li et al, 2017 ; Zhou et al, 2020 ). In the current study, 782 plasma samples from 711 pediatric patients submitted to our lab for routine EMIT assay for VPA monitoring were enrolled.…”

Comparison of ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and enzyme-multiplied immunoassay technique (EMIT) for quantification of voriconazole plasma concentration from Chinese patients

“…However, the entire procedure is time-consuming, usually taking approximately 3 h to obtain the first drug concentration result. However, the subsequent analyses are significantly faster, with a turnaround time of approximately 2–3 min/sample [ 19 ]. However, owing to the irregular arrival of clinical specimens, UPLC-MS/MS is not suitable for routine clinical monitoring.…”

“…Consequently, an alternative determination method that is simple, rapid, and user-friendly is required. The EMIT method is a commercially available analytical technique that is widely used for routine therapeutic drug monitoring of immunosuppressants [ 19 , 20 ] and anti-seizure drugs [ 21 ]. The EMIT approach is simple to execute and requires only ordinary laboratory equipment and no sophisticated equipment.…”

Quantitation of Mycophenolic Acid and Mycophenolic Acid Glucuronide in Serum or Plasma by LC‐MS/MS

“…There are various methods for the quantification of MPA and MPAG levels. These include immunassays, HPLC linked to an ultraviolet detector (HPLC/UV) and HPLC linked to a tandem mass spectrometer (HPLC‐MS/MS) (Danafar & Hamidi, 2015; Glahn‐Martinez et al., 2018; Kikuchi et al., 2018; Klepacki et al., 2012; Kunicki et al., 2015; Liu et al., 2021; Seyfinejad & Jouyban, 2021; Zhou et al., 2021). LC‐MS/MS is the most commonly used method for the quantification of MPA followed by immunoassays (College of American Pathologists Surveys, 2022).…”

“…LC‐MS/MS is the most commonly used method for the quantification of MPA followed by immunoassays (College of American Pathologists Surveys, 2022). However, immunoassays are prone to interferences from MPA metabolites and may overestimate MPA concentrations (De Nicolo et al., 2020; Kikuchi et al., 2018; Zhou et al., 2021). This could be a serious problem in renal failure, in which MPA metabolites accumulate to significantly high concentrations.…”