Elagolix, as a competitive gonadotropin-releasing hormone (GnRH) receptor antagonist, has been recently approved by the US FDA for the management of moderate to severe pain due to endometriosis in women. In this study, we developed and verified an analysis assay to detect the concentration level of elagolix in plasma from rats after sample preparation based on a newly validated ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) technique in this study. The process of sample preparation used acetonitrile for a quick and easy protein precipitation method and diazepam was engaged as the internal standard (IS). Then, gradient elution was used to elute elagolix and IS. The mobile phase used in the present experiment was consisted of solvent A (acetonitrile) and solvent B (water having formic acid with the volume ratio of 0.1%), and the type of the C18 column used was named Acquity UPLC BEH C18 column with the specification of 2.1 mm × 100 mm, 1.7 μm. Multiple reaction monitoring (MRM) in positive ion mode for the experiment was engaged to detect the level of elagolix with electrospray ionization (ESI) source by m/z 632.4 → 529.5 transition for quantification and m/z 632.4 → 177.1 transition for qualification. It was found that the method in the scope of 1–2000 ng/mL indicated excellent linearity (r² > 0.9983). The precision of this assay for intra-day was between 3.5 and 5.5%, and for inter-day was between 9.4 and 12.7%, respectively; the accuracy was 1.2–13.9% for the intra- and inter-day. The stability, extraction recovery, and matrix effect of the method were all in accordance with the rules of assay validation in biological medium proposed by FDA, whose application was also successfully used to determine the concentration of plasma elagolix from an experiment on pharmacokinetic investigation after oral administration of 15 mg/kg elagolix.

Elagolix 作为一种竞争性促性腺激素释放激素 (GnRH) 受体拮抗剂，最近已被美国 FDA 批准用于治疗女性子宫内膜异位症引起的中度至重度疼痛。在本研究中，我们基于本研究中新验证的超高效液相色谱串联质谱 (UPLC-MS/MS) 技术，开发并验证了一种分析方法，用于检测样品制备后大鼠血浆中 Elagolix 的浓度水平。样品制备过程使用乙腈作为快速简便的蛋白质沉淀方法，并使用地西泮作为内标 (IS)。然后，使用梯度洗脱来洗脱 Elagolix 和 IS。本实验所用流动相由溶剂A（乙腈）和溶剂B（体积比为0的甲酸水）组成。1%)，所用的 C18 色谱柱类型命名为 Acquity UPLC BEH C18 色谱柱，规格为 2.1 mm × 100 mm，1.7 μm。本实验采用正离子模式下的多反应监测 (MRM)，通过电喷雾电离 (ESI) 源检测 elagolix 的水平。m / z 632.4 → 529.5 跃迁用于定量，m / z 632.4 → 177.1 跃迁用于定性。结果表明，该方法在 1–2000 ng/mL 范围内具有出色的线性 ( r ² > 0.9983）。该测定的日内精密度在 3.5% 和 5.5% 之间，日间精密度分别在 9.4% 和 12.7% 之间；日内和日间的准确度为 1.2-13.9%。该方法的稳定性、提取回收率和基质效应均符合FDA提出的生物培养基测定验证规则，该方法的应用还成功用于口服后药代动力学研究实验中测定血浆elagolix的浓度。给予 15 mg/kg elagolix。