title: Validation of a free phenytoin assay on Cobas c501 analyzer using calibrators from Cobas Integra free phenytoin assay by comparing its performance with fluorescence polarization immunoassay for free phenytoin on the TDx analyzer.
abstract: For many years, fluorescence polarization immunoassay (FPIA) on the TDx analyzer has been used for determination of free phenytoin concentration. Recently Abbott Laboratories decided to discontinue the TDx analyzer and related assays on this analyzer. Free phenytoin assay is also available from Roche Diagnostics for application on the Cobas Integra analyzer (fluorescence polarization assay) but not on Cobas c510 analyzer. Free phenytoin calibrators from the Cobas Integra free phenytoin assay and the reagents from the KIMSphenytoin assay were used for the determination of free phenytoin on the Cobas c501 analyzer. The intra-run and inter-run precisions were both <7.2%. The assay was linear from 0.2 to 4 μg/ml. The free phenytoin assay on the Cobas c501 was compared with the FPIAassay on the TDx analyzer using sera from 25 patients receiving phenytoin (phenytoin concentration between 0.3 and 3.7 μg/ml). The following regression equation was observed: y = 0.9899 x + 0.0408 (r = 0.98, n = 25). In conclusion, the free phenytoin assay on the Cobas c501 analyzer is a valid alternative to free phenytoin assay on the TDx analyzer.
authors: Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School and Laboratory Services, Memorial-Hermann Hospital at the Texas Medical Center, Houston, TX, USA. Amitava.Dasgupta@uth.tmc.edu
authors: Amitava
authors: A
authors: Dasgupta
authors: Bonnette
authors: B
authors: Davis
authors: Loretta
authors: L
authors: Chow
mesh_terms: D001774:Blood Chemical Analysis / Q000295:instrumentation* / Q000379:methods* / Q000592:standards; D002138:Calibration; D016903:Drug Monitoring; D016231:Fluorescence Polarization Immunoassay / Q000379:methods* / Q000592:standards; D006801:Humans; D016014:Linear Models; D010672:Phenytoin / Q000097:blood*; D015203:Reproducibility of Results
chemical_list: D010672:Phenytoin