建立超效能液相層析－串聯式質譜儀定量四種抗排斥藥物（tacrolimus, sirolimus, everolimus, cyclosporine）的方法

Monitoring immunosuppressant drug level helps optimizing the drug dosage to decrease rejection, minimize drug toxicity and improve survival rates of transplant recipients. Many immunoassays can be applied for monitoring the concentration of immunosuppressant drugs. The main disadvantage of these immunoassays is cross-reaction between the parent drug and its metabolites, which may cause overestimation of drug concentration. The purpose for this study was to develop a method to quantitate four immunosuppressant drugs (tacrolimus, sirolimus, everolimus and cyclosporine) at the same time by on-line solid phase extraction (on-line SPE) and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). This method showed linearity over the calibrator range, r＞0.998 (1.1-38.5 ng/mL for tacrolimus, 1.1-46.1 ng/mL for sirolimus, 1.0-41.1 ng/mL for everolimus and 21.3-919.0 ng/mL for cyclosporine). The accuracy was between 90% and 113%. For intra-day and inter-day precision, the CV was ＜6.6%. This method showed no carryover or ion suppressant. By comparing the results obtained from our UPLC-MS/MS method to that of immunoassays, we have found that immunoassays overestimate the concentration of these four immunosuppressant drugs, especially for sirolimus. In conclusion, our newly developed UPLC-MS/MS method for simultaneous quantification four immunosuppressant drugs provides a more accurate measurement for immunosuppressant drugs in a clinical laboratory.