Comparison between ultra-performance liquid chromatography with tandem mass spectrometry and a chemiluminescence immunoassay in the determination of cyclosporin A and tacrolimus levels in whole blood

Regular immunosuppressant drug monitoring is important for maintaining the drug concentrations of organ recipients within the therapeutic range. The standardized liquid chromatography-tandem mass spectrometry (LC-TMS) technique has been used for the accurate analysis of immunosuppressive drugs. In the present study, the performance of the recently developed high-throughput, rapid ultra-performance liquid chromatography combined with tandem mass spectrometry (UPLC-TMS) method was validated for the simultaneous measurement of cyclosporin A and tacrolimus in whole blood. The method of measuring cyclosporin A and tacrolimus using UPLC-TMS was established and the precision, limit of detection (LOD), limit of quantitation (LOQ) and matrix effect were validated. In addition, the performance of UPLC-TMS was compared with that of a chemiluminescence immunoassay (CLIA) in >3,400 clinical specimens. The UPLC-TMS revealed a within-run and between-run precision of <8% and showed a bias of <5%. The LOD and LOQ were 2.0 and 2.5 ng/ml for cyclosporin A, and 0.3 and 0.4 ng/ml for tacrolimus, respectively. Interference from the matrix was not observed. The CLIA measurements of cyclosporin A and tacrolimus showed correlations corresponding with the formulae: Concentration(CLIA) = 1.18 × UPLC-TMS - 5.85; [95% CI: proportional, 1.16-1.19; constant, -6.86-(-4.81)] and Concentration(CLIA) = 1.14 × UPLC-TMS - 0.38; [(95% CI: proportional, 1.13-1.14; constant, -0.35-(-0.43)], respectively. The majority of results were higher for the immunoassay than for the UPLC-TMS. The newly developed rapid UPLC-TMS method was suitable for use with a large therapeutic concentration range of the analyzed immunosuppressive drugs. Sample preparation was simple and it was possible to detect several immunosuppressants simultaneously, thus significantly lowering the cost of analysis. In conclusion, this method may contribute to improved accuracy and may be preferred to immunoassays for the routine clinical measurement of immunosuppressive drug concentrations in whole blood.