title: Evaluation of EMIT Cyclosporine Assay for use with whole blood.
abstract: We evaluated the EMIT Cyclosporine Assay, designed for specific quantification of cyclosporine (CsA) in whole blood. The assay was run on the Roche Cobas Mira or Cobas Mira S analyzer. Analytical recovery from both normal donor whole blood and transplant patients' samples was within 17% of the standards. Measurement of diluted out-of-range samples also yielded excellent recovery (101-105%). Within-run, between-run, and total CVs were < or = 8.1%, 10.9%, and 12.1%, respectively. The detection limit was < 32 micrograms/L. The assay was linear from 0 to 500 micrograms/L. No significant cross-reactivity was observed for CsA metabolites AM1, AM19, and AM4N. Slight cross-reactivity occurred with metabolite AM9; 670 micrograms/L AM9 increased the measured CsA concentration by 49 micrograms/L. High concentrations of bilirubin, uric acid, triglycerides, and cholesterol, as well as 54 commonly coadministered drugs did not interfere with CsA quantification. Similarly, neither extreme values of hematocrit nor choice of anticoagulant affected CsA recovery. Sample extract stability was > 4 h, and assay calibration was stable for at least 2 weeks. Patients' samples analyzed by the EMIT assay showed strong correlation with both HPLC and 125I-RIA (r > 0.97). We conclude that the EMIT Cyclosporine Assay provides a convenient, accurate, and precise method for specific quantification of CsA in whole blood.
authors.affiliation: Syva Co., San Jose, CA 95135.
authors.forename: M H
authors.initials: MH
authors.lastname: Beresini
authors.forename: D
authors.initials: D
authors.lastname: Davalian
authors.forename: S
authors.initials: S
authors.lastname: Alexander
authors.forename: R
authors.initials: R
authors.lastname: Toton-Quinn
authors.forename: B
authors.initials: B
authors.lastname: Barnett
authors.forename: M J
authors.initials: MJ
authors.lastname: Cerelli
authors.forename: M W
authors.initials: MW
authors.lastname: Hu
authors.forename: D E
authors.initials: DE
authors.lastname: Berger
authors.forename: W P
authors.initials: WP
authors.lastname: Blohm
authors.forename: A
authors.initials: A
authors.lastname: Jaklitsch
mesh_terms: D002138:Calibration; D002851:Chromatography, High Pressure Liquid; D016572:Cyclosporine / Q000097:blood*; D004355:Drug Stability; D017248:Enzyme Multiplied Immunoassay Technique / Q000706:statistics & numerical data; D006400:Hematocrit; D006801:Humans; D008832:Microchemistry; D016377:Organ Transplantation; D011786:Quality Control; D011863:Radioimmunoassay; D011933:Reagent Kits, Diagnostic / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity
chemical_list: D011933:Reagent Kits, Diagnostic; D016572:Cyclosporine