title: Evaluation of a Methotrexate Chemiluminescent Microparticle Immunoassay:  Comparison to Fluorescence Polarization Immunoassay and Liquid Chromatography-Tandem Mass Spectrometry.
abstract: OBJECTIVE
  For most laboratories, methotrexate (MTX) concentrations are routinely monitored by fluorescence polarization immunoassay (FPIA). In anticipation of an announced withdrawal of the FPIA reagent on the Abbott TDxFLx (Abbott Diagnostics, Abbott Park, IL), we have evaluated a new reagent kit developed by Abbott on the Architect i1000, based on chemiluminescent microparticle immunoassay (CMIA).
  
  
  METHODS
  Precision, inaccuracy, and selectivity were assessed. Interassay variability was established using 75 plasma patient samples treated with MTX and analyzed by two methods: FPIA and liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS FOR MTX,: the intraday inaccuracy was between -6.37% and +3.52%, while interday performance was between -3.70% and 7.90%. Intraday and interday imprecision was less than 2.65% and less than 2.22%, respectively. The correlation coefficient between CMIA and FPIA or LC-MS/MS was 0.9969 and 0.9985, respectively.
  
  
  CONCLUSIONS
  These results comparing CMIA vs FPIA and LC-MS/MS indicate that CMIA is a suitable alternative to the FPIA method.
authors.affiliation: From the Department of Clinical Pharmacology, CHU de Nantes, Nantes, France. regis.bouquie@gmail.com.
authors.forename: Régis
authors.initials: R
authors.lastname: Bouquié
authors.affiliation: From the Department of Clinical Pharmacology, CHU de Nantes, Nantes, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Grégoire
authors.affiliation: From the Department of Clinical Pharmacology, CHU de Nantes, Nantes, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Hernando
authors.affiliation: From the Department of Clinical Pharmacology, CHU de Nantes, Nantes, France.
authors.forename: Claudine
authors.initials: C
authors.lastname: Azoulay
authors.affiliation: From the Department of Clinical Pharmacology, CHU de Nantes, Nantes, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Dailly
authors.affiliation: From the Department of Clinical Pharmacology, CHU de Nantes, Nantes, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Monteil-Ganière
authors.affiliation: From the Department of Clinical Pharmacology, CHU de Nantes, Nantes, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Pineau
authors.affiliation: From the Department of Clinical Pharmacology, CHU de Nantes, Nantes, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Deslandes
authors.affiliation: From the Department of Clinical Pharmacology, CHU de Nantes, Nantes, France.
authors.forename: Pascale
authors.initials: P
authors.lastname: Jolliet
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000964:Antimetabolites, Antineoplastic / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D002853:Chromatography, Liquid; D016903:Drug Monitoring / Q000379:methods*; D005260:Female; D016231:Fluorescence Polarization Immunoassay; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008297:Male; D008727:Methotrexate / Q000097:blood*; D008875:Middle Aged; D011933:Reagent Kits, Diagnostic; D053719:Tandem Mass Spectrometry; D055815:Young Adult
chemical_list: D000964:Antimetabolites, Antineoplastic; D011933:Reagent Kits, Diagnostic; D008727:Methotrexate
keywords: CMIA; Cancer; FPIA; Mass spectrometry; Methotrexate; Therapeutic drug monitoring