Sensitive, wide‐range and high‐throughput quantification of cyclosporine in whole blood using ultra‐performance liquid chromatography coupled to tandem mass spectrometry and comparison with an antibody‐conjugated magnetic immunoassay

Because either trough or peak concentration at 2 h after administration is measured in routine therapeutic drug monitoring for cyclosporine A (CyA), a quantification method with a wide‐range calibration curve capable of simultaneously measuring both concentrations is required. We developed a sensitive, wide‐range and high‐throughput quantification method for CyA in whole blood using ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS), and compared patients’ blood CyA levels measured by UPLC–MS/MS and antibody‐conjugated magnetic immunoassay (ACMIA). Whole blood samples were prepared by solid‐phase extraction using Oasis HLB μElution plate. The UPLC–MS/MS assay showed excellent linearity over a wide calibration range of 5–2500 ng/mL. Within‐batch accuracy and precision as well as batch‐to‐batch accuracy and precision fulfilled the criteria of US Food and Drug Administration guidelines. The blood CyA concentrations measured by the UPLC–MS/MS assay correlated strongly with those measured by ACMIA. A Bland–Altman plot showed a fixed error between CyA concentrations measured by the two methods, and the concentrations measured by the UPLC–MS/MS method were consistently lower than those measured by ACMIA. We have succeeded to develop a sensitive, wide‐range and high‐throughput quantification method for CyA in whole blood using UPLC–MS/MS.