title: Analytical performance of the Abbott Architect i2000 tacrolimus assay in Chinese patients after renal transplantation.
abstract: BACKGROUND
  Monitoring of tacrolimus concentrations has played a crucial role to control the efficacy versus adverse effects of treatment, because of the drug's narrow therapeutic range, inter- and intraindividual variabilities, and drug interactions mediated by hepatic cytochrome P450. Therefore, the stability of methods to monitor tacrolimus is of major importance. This study evaluated the analytical performance of the Abbott Architect i2000 tacrolimus assay, which was recently released in China to monitor tacrolimus therapy. We compared the results using the Abbott Architect i2000 Tacrolimus assay with the traditional Abbott IMx method.
  
  
  METHODS
  We measured concentrations of tacrolimus in 100 samples from renal transplant patients by Architect i2000 and the commonly used Abbott IMx.
  
  
  RESULTS
  We observed that the total %CV of the Architect i2000 assay was <10%, both at low and high concentration levels, with a functional sensitivity of <0.5 ng/mL. The Architect i2000 assay was linear over the reportable range with recoveries ranging from 90.6% to 106.7%. In addition, this assay was not affected by high concentrations of hemoglobin, lipids, or bilirubin in the samples. The 2 assays yielded similar results. The regression equation obtained from the Passing Bablok analysis was: y = 0.8788x - 0.3485 with a Spearman correlation coefficient (r) of 0.9922. The bias plot between the Architect i2000 and Abbott IMx assay yielded an average negative bias (-1.4 ng/mL).
  
  
  CONCLUSIONS
  We concluded that, because of its high precision and sensitivity, low cross-reactivity, and acceptable accuracy, the Architect i2000 assay is a suitable alternative to monitor tacrolimus concentrations in renal transplant recipients.
authors.affiliation: Department of Clinical Laboratory, Peking University First Hospital, Beijing, China. rockandfriend@yahoo.com.cn
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Li
authors.forename: C L
authors.initials: CL
authors.lastname: Yan
authors.forename: R
authors.initials: R
authors.lastname: Yan
authors.forename: Z R
authors.initials: ZR
authors.lastname: Feng
mesh_terms: D002681:China; D016903:Drug Monitoring; D006801:Humans; D007166:Immunosuppressive Agents / Q000097:blood*; D016030:Kidney Transplantation; D057230:Limit of Detection; D015203:Reproducibility of Results; D016559:Tacrolimus / Q000097:blood*
chemical_list: D007166:Immunosuppressive Agents; D016559:Tacrolimus