Abstract Warfarin (WRN) use is plagued by response fluctuation which is managed by dose adjustment. The plasma WRN level had always been an abandoned prerequisite for dose adjustment. However, recent reports had correlated WRN level to the consumed dose. More importantly, the intra-individual alteration in WRN level was found proportional to response fluctuation. This renewed the interest to use WRN level prior to dose adjustment to account for dispensing errors or inadequate adherence. Detection of possibly interacting drugs may further assess compliance and enable a wiser dose adjustment. In this study, an LC–MS/MS assay was developed and validated for the determination of the WRN and the simultaneous detection of interacting drugs in citrated plasma samples normally collected for monitoring international normalized ration (INR). Samples were prepared by liquid-liquid extraction. Separation of WRN and interacting drugs (n = 19) was achieved on an Inertsil®C18 column using a gradient elution program. The assay was applied in 96 plasma samples from patients. The developed method was linear, accurate and precise for WRN determination with average recovery of 99.5 ± 8.4% and no relative matrix effect. WRN plasma level was measured in all samples and possible interacting drugs were detected. An improved WRN-response correlation was observed inter-individually when patient variability was reduced. Our results support the significance of WRN monitoring and suggest the additional monitoring of other interacting drugs for integrated evaluation of patient adherence. The developed method enables ruling-out inadequate adherence prior to unnecessary dose adjustment and highlights the need to strengthen patient education procedures.

中文翻译：

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LC-MS/MS 分析用于评估接受华法林维持治疗的患者的医疗依从性

摘要 华法林 (WRN) 的使用受到通过剂量调整管理的反应波动的困扰。血浆 WRN 水平一直是剂量调整的一个被放弃的先决条件。然而，最近的报告将 WRN 水平与消耗剂量相关联。更重要的是，发现 WRN 水平的个体内变化与响应波动成正比。这重新引起了在剂量调整之前使用 WRN 水平以解决配药错误或依从性不足的兴趣。检测可能相互作用的药物可以进一步评估依从性并实现更明智的剂量调整。在本研究中，开发并验证了 LC-MS/MS 测定法，用于测定 WRN 并同时检测通常用于监测国际标准化定量 (INR) 的柠檬酸盐血浆样品中的相互作用药物。通过液-液萃取制备样品。使用梯度洗脱程序在 Inertsil®C18 色谱柱上实现 WRN 和相互作用药物（n = 19）的分离。该测定应用于来自患者的 96 份血浆样品。所开发的方法线性、准确和精确，可用于 WRN 测定，平均回收率为 99.5 ± 8.4%，无相对基质效应。在所有样本中测量 WRN 血浆水平，并检测到可能的相互作用药物。当患者变异性降低时，观察到个体间改进的 WRN 反应相关性。我们的结果支持 WRN 监测的重要性，并建议对其他相互作用药物进行额外监测，以综合评估患者的依从性。