Division of Outcomes and Translational Sciences, College of Pharmacy, The Ohio State University, Columbus, OH, USA.
Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH, USA.
J Chromatogr B Analyt Technol Biomed Life Sci. 2024 May 1;1238:124106. doi: 10.1016/j.jchromb.2024.124106. Epub 2024 Apr 2.
A liquid chromatography - electrospray ionization-mass spectrometry (LC-ESI-MS) method was developed for the quantification of letrozole, a third-generation aromatase inhibitor, and its main carbinol metabolite (CM) in support of murine pharmacokinetic studies. Using polarity switching, simultaneous ESI-MS measurement of letrozole and CM was achieved in positive and negative mode, respectively. The assay procedure involved a one-step protein precipitation and extraction of all analytes from mouse plasma requiring only 5 μL of sample. Separation was optimized on an Accucore aQ column with gradient elution at a flow rate of 0.4 mL/min in 5 min. Two calibration curves per day over four consecutive measurement days showed satisfactory linear responses (r > 0.99) over concentration ranges of 5-1000 ng/mL and 20-2000 ng/mL for letrozole and CM, respectively. No matrix effect was found, and the mean extraction recoveries were 103-108 % for letrozole and 99.8-107 % for CM. Precision and accuracy within a single run and over four consecutive measurement days were verified to be within acceptable limits. Application of the developed method to preclinical pharmacokinetic studies in mice receiving oral letrozole at a dose 1 or 10 mg/kg revealed that the systemic exposure to letrozole was dose-, formulation-, and strain-dependent. These findings may inform the future design of preclinical studies aimed at refining the pharmacological profile of this clinically important drug.
建立了一种液相色谱-电喷雾电离-质谱（LC-ESI-MS）法，用于定量测定第三代芳香酶抑制剂来曲唑及其主要的醇代谢物（CM），以支持鼠类药代动力学研究。采用极性切换，分别在正、负离子模式下实现了来曲唑和 CM 的同时 ESI-MS 测量。该测定程序涉及一步蛋白沉淀，仅需 5μL 样品即可从鼠血浆中提取所有分析物。在 Accucore aQ 柱上以 0.4 mL/min 的流速进行梯度洗脱，5 分钟内实现分离。连续 4 天每天进行 2 条校准曲线，结果表明来曲唑和 CM 的浓度范围分别为 5-1000ng/mL 和 20-2000ng/mL 时，均具有满意的线性响应（r>0.99）。未发现基质效应，来曲唑和 CM 的平均提取回收率分别为 103-108%和 99.8-107%。单日内和连续 4 天内的精密度和准确度验证均符合可接受标准。该方法应用于接受 1 或 10mg/kg 口服来曲唑的小鼠临床前药代动力学研究，结果表明来曲唑的全身暴露与剂量、制剂和品系有关。这些发现可能为未来旨在优化这种临床重要药物的药理学特征的临床前研究提供信息。
