Rule Geoffrey S, Rockwood Alan L, Johnson-Davis Kamisha L
*ARUP Institute for Clinical and Experimental Pathology, ARUP Laboratories; and †Department of Pathology, University of Utah Health Sciences Center, Salt Lake City.
Ther Drug Monit. 2015 Aug;37(4):472-8. doi: 10.1097/FTD.0000000000000166.
A liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been validated for use in therapeutic monitoring of the drug leflunomide in human serum and plasma. Because of concerns of teratogenicity, it is recommended that women who want to become pregnant have concentrations below 0.02 mcg/mL, although therapeutic levels are generally greater than 20 mcg/mL. Consequently, the method required a 40,000-fold dynamic range, which was achieved by dividing the curve range into 2 separate regions but with a single extraction procedure used for both.
A chromatographic separation was achieved between the parent drug and the active metabolite, teriflunomide (A77 1726), and the latter was quantified across a quantitative range of 0.005-200 mcg/mL. Samples were evaluated in an upper curve region first, with dilution, to determine whether the drug concentrations were in an appropriate therapeutic range. Samples that fell below the upper region were then reevaluated in the lower region without dilution.
The method was shown to be reliable, with good accuracy and precision statistics, and acceptable quantitation using 4 different collection tube types. Mean accuracy over 6 control concentrations was within 5.4%, over 5 validation runs, whereas %coefficient of variation (CV) was within 8.15%. Evaluation of sodium heparin, KEDTA, NaF/K oxalate, and plain serum tubes from 6 separate individuals at the lower limit of quantification (LLOQ) showed no influence on the ability to quantify teriflunomide accurately. Regression equations for a curve range of 0.005-1 mcg/mL gave R values of 0.998 or better, whereas the range 0.8-200 mcg/mL had R values of 0.997 or better.
The authors have developed and validated a method that allows quantification of leflunomide across a 40,000-fold range of 0.005-200 mcg/mL.
一种液相色谱串联质谱（LC-MS/MS）方法已通过验证，可用于监测人血清和血浆中药物来氟米特的治疗情况。由于存在致畸性担忧，建议想要怀孕的女性来氟米特浓度低于0.02 mcg/mL，而治疗水平通常大于20 mcg/mL。因此，该方法需要40000倍的动态范围，这是通过将曲线范围分为2个单独区域但对两者使用单一提取程序来实现的。
实现了母体药物与活性代谢物特立氟胺（A77 1726）之间的色谱分离，并在0.005 - 200 mcg/mL的定量范围内对后者进行定量。首先对样品在曲线的上部区域进行稀释评估，以确定药物浓度是否处于适当的治疗范围内。然后对低于上部区域的样品在下部区域进行不稀释的重新评估。
该方法被证明是可靠的，具有良好的准确度和精密度统计数据，并且使用4种不同类型的收集管进行定量是可接受的。在5次验证运行中，6个对照浓度的平均准确度在5.4%以内，而变异系数（CV）%在8.15%以内。在定量下限（LLOQ）对6个不同个体的肝素钠、KEDTA、氟化钠/草酸钾和普通血清管进行评估，结果表明对准确定量特立氟胺的能力没有影响。0.005 - 1 mcg/mL曲线范围的回归方程R值为0.998或更高，而0.8 - 200 mcg/mL范围的R值为0.997或更高。
作者开发并验证了一种方法，该方法能够在0.005 - 200 mcg/mL的40000倍范围内对来氟米特进行定量。
