Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands.
Department of Internal Medicine (Nephrology), Leiden University Medical Center, Leiden, The Netherlands.
Br J Clin Pharmacol. 2022 Nov;88(11):4854-4869. doi: 10.1111/bcp.15433. Epub 2022 Jun 17.
Immunosuppressant and kidney function monitoring are crucial for kidney transplant recipient follow-up. Microsamples enable remote sampling and minimise patient burden as compared to conventional venous sampling at the clinic. We developed a liquid chromatography-tandem mass spectrometry assay to quantify tacrolimus, mycophenolic acid (MPA), creatinine and iohexol in dried blood spot (DBS), and volumetric absorptive microsample (VAMS) samples.
The assay was successfully validated analytically for all analytes. Clinical validation was conducted by direct comparison of paired DBS, VAMS and venous reference samples from 25 kidney transplant recipients. Patients received iohexol 5-15 minutes before immunosuppressant intake and were sampled 0, 1, 2 and 3 hours thereafter, enabling tacrolimus and MPA area under the concentration-time curve (AUC) and creatinine-based and iohexol-based glomerular filtration rate (GFR) estimation. Method agreement was evaluated using Passing-Bablok regression, Bland-Altman analysis and the percentages of values within 15-30% of the reference (P -P ) with a P acceptance threshold of 80%.
For DBS samples, method agreement was excellent for tacrolimus trough concentrations (n = 25, P = 92.0%) and AUCs (n = 25; P = 95.8%) and adequate for creatinine-based GFR trend monitoring (n = 25; P = 80%). DBS-based MPA AUC assessment showed suboptimal agreement (n = 16; P = 68.8%), but was considered acceptable given its P of 100%. The assay performed inadequately for DBS-based iohexol GFR determination (n = 24; P = 75%). The VAMS technique generally showed inferior performance, but can be considered for certain situations.
The assay was successfully validated for tacrolimus, MPA and creatinine quantification in DBS samples, enabling simultaneous remote kidney function trend monitoring and immunosuppressant therapeutic drug monitoring in kidney transplant recipients.
免疫抑制剂和肾功能监测对于肾移植受者的随访至关重要。与在诊所进行传统静脉采样相比，微采样能够进行远程采样并最大程度地减少患者的负担。我们开发了一种液相色谱-串联质谱测定法，用于定量测定干血斑（DBS）和体积吸收微样本（VAMS）中的他克莫司、霉酚酸（MPA）、肌酐和碘海醇。
该测定法在所有分析物上均成功进行了分析验证。通过直接比较 25 例肾移植受者的配对 DBS、VAMS 和静脉参考样本进行了临床验证。患者在接受免疫抑制剂摄入前 5-15 分钟接受了碘海醇注射，并在之后的 0、1、2 和 3 小时进行采样，从而能够估算他克莫司和 MPA 的浓度-时间曲线下面积（AUC）以及基于肌酐和碘海醇的肾小球滤过率（GFR）。使用 Passing-Bablok 回归、Bland-Altman 分析和在参考值的 15-30%范围内的百分比（P -P ）以及 80%的接受阈值（P ）评估方法的一致性。
对于 DBS 样本，他克莫司谷浓度（n=25，P=92.0%）和 AUC（n=25，P=95.8%）的方法一致性非常好，肌酐的 GFR 趋势监测（n=25，P=80%）的方法一致性也很好。基于 DBS 的 MPA AUC 评估的方法一致性较差（n=16，P=68.8%），但考虑到其 P 值为 100%，这种方法是可以接受的。DBS 碘海醇 GFR 测定的方法性能不佳（n=24，P=75%）。VAMS 技术通常表现不佳，但在某些情况下可以考虑使用。
该测定法已成功验证用于 DBS 样本中他克莫司、MPA 和肌酐的定量，可同时对肾移植受者进行远程肾功能趋势监测和免疫抑制剂治疗药物监测。
