Determination of mycophenolic acid plasma levels in renal transplant recipients co-administered sirolimus: comparison of an enzyme multiplied immunoassay technique (EMIT) and liquid chromatography-tandem mass spectrometry

Ther Drug Monit. 2006 Apr;28(2):274-7. doi: 10.1097/01.ftd.0000197092.84935.ef.


This study was designed to compare the enzyme multiplied immunoassay technique (EMIT) and a specific ;liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of mycophenolic acid (MPA) concentrations in plasma samples collected from renal transplant patients receiving mycophenolate mofetil in association with sirolimus and corticosteroids. Ten-point blood concentration-time profiles, between pre-dose (C0) and 9-hour post-dose, were obtained on day 7, day 14, months 1, 2, and 3 posttransplantation in 8 patients. MPA plasma concentrations were measured simultaneously with both EMIT and LC-MS/MS. Higher concentrations were obtained with EMIT. The mean (+/-SD) absolute difference was +0.84 +/- 1.93 mg/L, which corresponds to a significant overestimation of 18.7 +/- 2 6.8% with EMIT, with variations depending on the time elapsed since transplantation. An EMIT overestimation of 16.7 +/- 22.5% also was obtained for the MPA areas under the curve calculated using the trapezoidal rule.

Publication types

  • Comparative Study

MeSH terms

  • Area Under Curve
  • Chromatography, Liquid / methods*
  • Creatinine / blood
  • Drug Monitoring / methods
  • Enzyme Inhibitors / blood
  • Enzyme Inhibitors / pharmacokinetics
  • Enzyme Inhibitors / therapeutic use
  • Enzyme Multiplied Immunoassay Technique*
  • Graft Rejection / prevention & control
  • Humans
  • Kidney Transplantation*
  • Mass Spectrometry / methods*
  • Mycophenolic Acid / blood*
  • Mycophenolic Acid / pharmacokinetics
  • Mycophenolic Acid / therapeutic use
  • Sirolimus / blood
  • Sirolimus / pharmacokinetics
  • Sirolimus / therapeutic use
  • Time Factors


  • Enzyme Inhibitors
  • Creatinine
  • Mycophenolic Acid
  • Sirolimus