Simultaneous and rapid analysis of cyclosporin A and creatinine in finger prick blood samples using liquid chromatography tandem mass spectrometry and its application in C2 monitoring

Brian G. Keevil, David P. Tierney, Donald P. Cooper, Michael R. Morris, Ali Machaal, Nizar Yonan

    Research output: Contribution to journalArticlepeer-review

    Abstract

    A simple and rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the simultaneous analysis of cyclosporin A (CsA) and creatinine using capillary blood has been developed. Venous and capillary blood samples were taken predose and at C2 from 65 heart and lung transplant recipients (65 × 4 samples). For comparisons, serum creatinine and blood CsA concentrations were measured by the Jaffe and EMIT methods, respectively, using an Olympus AU600 analyzer. For the LC-MS/MS assay, samples were prepared in a 96 × 700-μL well block by adding 10 μL of blood (or serum) to 40 μL of 0.1 mol/L zinc sulphate solution containing deuterated creatinine internal standard. Proteins were precipitated by adding 100 μL acetonitrile containing ascomycin internal standard. After vigorous mixing and centrifugation, 5 μL of the supernatant was injected into the LC-MS/MS system. A Waters 2795 high-performance liquid chromatography (HPLC) system was used to elute a C18 cartridge (3 mm × 4 mm) at 0.6 mL/min with a step gradient of 50-100% methanol containing 2 mmol/L ammonium acetate and 0.1% (v/v) formic acid. The column was maintained at 55°C, and the retention times were creatinine, 0.4 minutes; ascomycin, 0.98 minutes; and CsA, 1.2 minutes. Cycle time was 2.5 minutes, injection to injection. The analytes were monitored using a Quattro microtandem mass spectrometer operated in multiple reaction monitoring mode using the following transitions: creatinine, m/z 114>44; d3-creatinine (IS), m/z 117>47; ascomycin (IS), m/z 809>756; and CsA, m/z 1,220>1,203. Assay characteristics were CsA intraassay CV, 3.6-3.0% (33-1,500 μg/L); CsA interassay CV, 6.7-2.5% (10-5,000 μg/L); LC-MS/MS capillary [CsA] = 0.99 × LC-MS/MS venous [CsA] - 4.2, R = 0.98; and LC-MS/MS venous [CsA] = 0.93 × EMIT venous [CsA] + 2.9, R = 0.98. Creatinine intraassay CV, 6.6-2.5% (20-720 μmol/L); interassay CV, 5.7-3.3% (80-590 μmol/L); LC-MS/MS capillary [creatinine] = 0.99 Jaffe plasma [creatinine] -42.6, R = 0.87. Total time for the preparation and analysis of 30 samples was approximately 2 hours. This assay will provide a flexible, robust, and cost-effective solution for the monitoring of CsA and creatinine in transplant recipients with potential applications in pediatric medicine and pharmacokinetic studies, in which frequent sampling is required.
    Original languageEnglish
    Pages (from-to)757-767
    Number of pages10
    JournalTherapeutic Drug Monitoring
    Volume24
    Issue number6
    DOIs
    Publication statusPublished - Dec 2002

    Keywords

    • Cyclosporin
    • Tandem mass spectrometry

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