title: Evaluation of a fluorescent polarization immunoassay for whole blood everolimus determination using samples from renal transplant recipients.
abstract: OBJECTIVE
  This study compared the performance of a fluorescent polarization immunoassay (FPIA) against HPLC-tandem mass spectrometry (HPLC-MS) for the measurement of everolimus in renal transplant recipients.
  
  
  METHODS
  A total of 333 pre-dose samples from 45 renal transplant patients were analyzed by FPIA and HPLC-MS.
  
  
  RESULTS
  The inter-batch inaccuracy and precision of the FPIA for control samples were <or=6% and <or=13.0%, respectively (n = 17). The comparison of patient results yielded the Deming regression equation FPIA = 1.19 x HPLC-MS + 0.51. The mean bias was 24.4% (95% CI: -3.0 to 54.2%, range: -30.1% to 79.4%).
  
  
  CONCLUSIONS
  The FPIA had acceptable analytical performance during the study but compared to HPLC-MS overestimated everolimus in patient samples. This overestimation is probably due to calibration differences between the methods and cross-reactivity of the FPIA antibody with everolimus metabolites. The clinical importance of the observed overestimation by FPIA requires further investigation.
authors.affiliation: Australian Bioanalytical Services Pty Ltd, Princess Alexandra Hospital, Brisbane 4102, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Salm
authors.forename: Christopher
authors.initials: C
authors.lastname: Warnholtz
authors.forename: Jared
authors.initials: J
authors.lastname: Boyd
authors.forename: Lili
authors.initials: L
authors.lastname: Arabshahi
authors.forename: Peter
authors.initials: P
authors.lastname: Marbach
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Taylor
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003429:Cross Reactions; D000068338:Everolimus; D016231:Fluorescence Polarization Immunoassay / Q000379:methods*; D006801:Humans; D007166:Immunosuppressive Agents / Q000097:blood*; D016030:Kidney Transplantation; D008137:Longitudinal Studies; D020123:Sirolimus / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D007166:Immunosuppressive Agents; D000068338:Everolimus; D020123:Sirolimus