A Comparison of the Immunochemical Methods, PETINIA and EMIT, With That of HPLC-UV for the Routine Monitoring of Mycophenolic Acid in Heart Transplant Patients

Abstract

The new immunochemical PETINIA method was associated with significantly higher MPA concentrations in routine therapeutic drug monitoring samples from heart transplant patients. The magnitude of the MPA overestimation was similar to that observed by use of the EMIT method.

A comprehensive review of the published assays for the quantitation of the immunosuppressant drug mycophenolic acid and its glucuronidated metabolites in biological fluids

“…Further in-depth statistical analysis using BlandAltman analysis or Passing Bablok regression confirmed that the use of either of the two enzymatic assays would lead to a positive bias in the estimation of MPA in the routine or pharmacokinetic samples in the patients. While the bias was 33.48% for PETINA assay, it ranged from 24.5 to 42.77% in the case of EMIT assay as compared with the reference HPLC method (Kunicki et al, 2015). A few takeaways from this report included the following: (a) the bias in the results (enzymatic vs HPLC) was directly proportional to MPA concentration; (b) one of the culprits for over estimation of MPA levels by enzymatic assays was the AcMPAG metabolite; and (c) cross-reactivity with other MPA metabolites may have a role to play in the observed positive bias (Kunicki et al, 2015).…”

“…While the bias was 33.48% for PETINA assay, it ranged from 24.5 to 42.77% in the case of EMIT assay as compared with the reference HPLC method (Kunicki et al, 2015). A few takeaways from this report included the following: (a) the bias in the results (enzymatic vs HPLC) was directly proportional to MPA concentration; (b) one of the culprits for over estimation of MPA levels by enzymatic assays was the AcMPAG metabolite; and (c) cross-reactivity with other MPA metabolites may have a role to play in the observed positive bias (Kunicki et al, 2015). While it may be difficult to exactly pin-point the overestimation of MPA rendered by enzymatic assays, the published data collectively suggest that the bias could be >20% in many instances.…”

“…Enzymatic assays and comparison with chromatographic methods Kunicki et al (2015 have assessed the use of two enzymatic procedures namely particle enhanced turbidometric inhibition immunoassay (PETINA) and enzyme multiplied immunoassay technique (EMIT) for the measurement of MPA in heart transplant patients in relation to a reference HPLC-UV assay. PETINA assay was used to measure MPA levels in 194 trough-level samples at steady state.…”

Determination of mycophenolic acid in human plasma by ultra‐performance liquid chromatography–tandem mass spectrometry and its pharmacokinetic application in kidney transplant patients

“…The quantification of MPA can be performed by immunoassays commercially available (Dasgupta, Tso, & Chow, ; Kunicki, Pawinski, Boczek, Was, & Bodnar‐Broniarczyk, ); however, these methods can overestimate MPA plasma concentration as a result of cross‐reactivity of MPA metabolites with the monoclonal antibodies, resulting in limited specificity and sensitivity (Buchwald et al, ; Guo et al, ). One option to improve MPA quantification is applying ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) methods.…”

Free mycophenolic acid determination in human plasma ultrafiltrate by a validated liquid chromatography–tandem mass spectrometry method

“…Certain immunoassays, such as enzyme‐multiplied immunoassay technique (EMIT), cloned enzyme donor immunoassay (CEDIA), Roche enzymatic assay or recently developed particle enhanced turbidimetric inhibition immunoassay (PETINIA), produce biased results due to cross‐reactivity with the minor but pharmacologically active MPA metabolite – acyl glucuronide (AcMPAG). In consequence, MPA concentrations measured by immunoassays can be overestimated (Dasgupta, ; Dasgupta, Tso, & Chow, ; Kelly & Butch, ; Kunicki, Pawiński, Boczek, Waś, & Bodnar‐Broniarczyk, ). Therefore, high‐performance liquid chromatography (HPLC) combined with either ultraviolet (UV) or mass spectrometric (MS) detector is considered as a standard method for MPA determination (Dasgupta, , b).…”