Development and validation of a rapid HPLC‐MS/MS method for simultaneous determination of cyclosporine A and tacrolimus in whole blood for routine therapeutic drug monitoring in organ transplantation

Background Therapeutic drug monitoring is an integral part of organ transplantation. A rapid, simple, economical, and robust high‐performance liquid chromatography‐tandem mass spectrometry (HPLC‐MS/MS) method for simultaneously determining the immunosuppressants cyclosporine A and tacrolimus might increase detection efficiency. Methods In this study, we developed and validated a rapid HPLC‐MS/MS method. Whole blood samples of 100 μL were prepared by protein precipitation with acetonitrile and 0.5 mol. L −1 ZnSO 4 . Chromatography was performed on a pre‐column using a gradient elution with 20 mmol. L −1 ammonium formate and 0.1% (v/v) formic acid in water (mobile phase A) and 0.1% (v/v) formic acid in methanol (mobile phase B) at a flow rate of 1.5 mL.min −1 . The analysis time was 2.2 min. Electrospray ionization and multiple reaction monitoring were performed. The lower limit of quantification was set at 1 ng. L −1 for tacrolimus and 50 ng. L −1 for cyclosporine A. Results The method showed adequate accuracy and precision with a sufficient linear range. The calibration curve range of tacrolimus and cyclosporine A was 1–30 and 50–1500 ng·mL‐ 1 , respectively. All correlation coefficients were >0.99. Conclusions The developed HPLC‐MS/MS is rapid and can be used for simultaneous monitoring of tacrolimus and cyclosporine A.