Ruggenthaler M, Grass J, Schuh W, Huber C G, Reischl R J
SANDOZ GmbH, Biochemiestraße 10, A-6250 Kundl/Tirol, Austria; Department of Molecular Biology, Division of Chemistry and Bioanalytics,University of Salzburg, Hellbrunner Straße 34, A-5020 Salzburg, Austria.
SANDOZ GmbH, Biochemiestraße 10, A-6250 Kundl/Tirol, Austria.
J Pharm Biomed Anal. 2017 Feb 20;135:140-152. doi: 10.1016/j.jpba.2016.12.002. Epub 2016 Dec 14.
The structural elucidation of unknown pharmaceutical impurities plays an important role in the quality control of newly developed and well-established active pharmaceutical ingredients (APIs). The United States Pharmacopeia (USP) monograph for the API Levothyroxine Sodium, a synthetic thyroid hormone, features two high pressure liquid chromatography (HPLC) methods using UV-VIS absorption detection to determine organic impurities in the drug substance. The impurity profile of the first USP method ("Procedure 1") has already been extensively studied, however for the second method ("Procedure 2"), which exhibits a significantly different impurity profile, no wholistic structural elucidation of impurities has been performed yet. Applying minor modifications to the chromatographic parameters of USP "Procedure 2" and using various comprehensive structural elucidation methods such as high resolution tandem mass spectrometry with on-line hydrogen-deuterium (H/D) exchange or two-dimensional nuclear magnetic resonance spectroscopy (NMR) we gained new insights about the complex impurity profile of the synthetic thyroid hormone. This resulted in the characterization of 24 compounds previously unknown to literature and the introduction of two new classes of Levothyroxine Sodium impurities. Five novel compounds were unambiguously identified via isolation or synthesis of reference substances and subsequent NMR spectroscopic investigation. Additionally, Collision-Induced Dissociation (CID)-type fragmentation of identified major impurities as well as neutral loss fragmentation patterns of many characterized impurities were discussed.
未知药物杂质的结构解析在新开发和成熟的活性药物成分（API）的质量控制中起着重要作用。美国药典（USP）中关于合成甲状腺激素左甲状腺素钠原料药的专论介绍了两种采用紫外-可见吸收检测的高效液相色谱（HPLC）方法，用于测定原料药中的有机杂质。USP的第一种方法（“方法1”）的杂质谱已得到广泛研究，然而，对于杂质谱显著不同的第二种方法（“方法2”），尚未对杂质进行全面的结构解析。通过对USP“方法2”的色谱参数进行微小调整，并使用各种综合结构解析方法，如带有在线氢-氘（H/D）交换的高分辨率串联质谱或二维核磁共振光谱（NMR），我们对合成甲状腺激素复杂的杂质谱有了新的认识。这导致鉴定出24种文献中未知的化合物，并引入了两类新的左甲状腺素钠杂质。通过分离或合成对照品并随后进行核磁共振光谱研究，明确鉴定出了5种新化合物。此外，还讨论了已鉴定主要杂质的碰撞诱导解离（CID）型碎裂以及许多已表征杂质的中性丢失碎裂模式。
