Clin Chem Lab Med. 2014 Mar;52(3):381-9. doi: 10.1515/cclm-2013-0594.
Linezolid serum concentrations have been shown to be highly variable in critically ill patients with often sub-therapeutic drug levels regarding minimal inhibitory concentrations for relevant pathogens. Consequently, therapeutic drug monitoring of linezolid must be considered, requiring a reliable and convenient analytical method. We therefore developed and validated an LC-MS/MS method applying isotope dilution internal standardization and on-line solid phase extraction for serum linezolid quantification.
Sample preparation was based on protein precipitation and on-line solid phase extraction with two-dimensional liquid chromatography and column switching. Three-fold deuterated linezolid was used as the internal standard. The method was validated involving two separate LC-MS/MS systems covering the concentration range of 0.13-32 mg/L. The run time was 4 min.
Validation revealed good analytical performance, with inaccuracy <6% and imprecision of <7.3% (CV) for six quality control samples (0.38-16.0 mg/L). The method was found to be robust during the validation process and during a pharmacokinetic study so far involving 600 samples. Comparative measurements on two LC-MS/MS systems revealed close agreement.
This LC-MS/MS assay described herein is a convenient, robust and reliable method for linezolid quantification in serum which can be routinely applied using different LC-MS/MS systems. The method can be used for clinical studies and subsequent TDM of linezolid.
在重症患者中，利奈唑胺的血清浓度变化很大，通常低于相关病原体的最低抑菌浓度，导致药物治疗水平不足。因此，必须考虑对利奈唑胺进行治疗药物监测，这需要一种可靠且方便的分析方法。为此，我们开发并验证了一种 LC-MS/MS 方法，该方法采用同位素稀释内标法和在线固相萃取技术，用于血清利奈唑胺的定量分析。
样品制备基于蛋白质沉淀和在线固相萃取，采用二维液相色谱和柱切换技术。三倍氘代利奈唑胺被用作内标。该方法经过两个独立的 LC-MS/MS 系统进行验证，涵盖了 0.13-32mg/L 的浓度范围。运行时间为 4 分钟。
验证结果表明，该方法具有良好的分析性能，6 个质控样品（0.38-16.0mg/L）的准确度<6%，精密度<7.3%（CV）。在验证过程中和迄今为止涉及 600 个样本的药代动力学研究中，该方法表现出稳健性。在两个 LC-MS/MS 系统上进行的比较测量显示出良好的一致性。
本文所述的 LC-MS/MS 测定法是一种方便、稳健且可靠的方法，可用于血清中利奈唑胺的定量分析，可使用不同的 LC-MS/MS 系统进行常规应用。该方法可用于临床研究和随后的利奈唑胺治疗药物监测。
