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This Article Full Text Full Text (PDF) Data Supplement All Versions of this Article: clinchem.2004.043992v1 51/2/457    most recent Submit an electronic Letter to the Editor about this paper Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Annesley, T. M. Search for Related Content PubMed PubMed Citation Articles by Annesley, T. M. Related Collections Drug Monitoring and Toxicology

Application of Commercial Calibrators for the Analysis of Immunosuppressant Drugs in Whole Blood

University of Michigan Health Systems, 1500 East Medical Center Dr., Ann Arbor, MI 48109-0054; e-mail annesley@umich.edu

The first 300 words of the full text of this article appear below.

Multiple immunosuppressant drugs are now available to prevent organ rejection. Because of their different modes of action, these drugs are often prescribed together as part of a multidrug protocol. This has created a challenge for clinical laboratories to analyze multiple immunosuppressant drugs in the same blood specimen. HPLC–mass spectrometry (HPLC-MS) or -tandem mass spectrometry (HPLC-MS/MS) (1)(2)(3)(4)(5)(6) assays can measure all of the common drugs.

A practical issue with the use of HPLC-MS/MS is the necessity of preparing whole-blood calibrators containing cyclosporine, tacrolimus, and sirolimus. With the introduction of everolimus, yet another set of calibrators will be needed. As with any assay for which in-house calibrators are prepared, this added variable will contribute to the interlaboratory differences observed in proficiency testing programs. The availability of either standard reference materials (SRMs) or uniform calibrators for use among different laboratories would help with this problem.

Recently, the Thermo Electron and Waters Corporations announced alliances to distribute Chromsystems products. Among the Chromsystems products are whole-blood calibrators and controls for cyclosporine, tacrolimus, and sirolimus, with everolimus to be added in future lots of material. The availability of multiconstituent whole-blood calibrators or controls would address the issues stated above, if validation of their performance were to be performed in actual laboratory use. With this in mind I undertook a set of experiments to answer several important questions: (a) Do the assigned concentrations in these whole-blood materials appear to be accurate? (b) When they are used as the calibrators, do the assays yield results for patient specimens that are similar to those obtained when validated in-house calibrators are used for the assays? (c) Do they yield expected results for separate commercial whole-blood controls and for proficiency testing samples? (. . . [Full Text of this Article]

The following articles in journals at HighWire Press have cited this article:

				T. M. Annesley Methanol-Associated Matrix Effects in Electrospray Ionization Tandem Mass Spectrometry Clin. Chem., October 1, 2007; 53(10): 1827 - 1834. [Abstract] [Full Text] [PDF]