Taub Mitchell E, Ludwig-Schwellinger Eva, Ishiguro Naoki, Kishimoto Wataru, Yu Hongbin, Wagner Klaus, Tweedie Donald
Drug Metabolism & Pharmacokinetics, Boehringer Ingelheim Pharmaceuticals, Inc. , Ridgefield, Connecticut 06877-0368, United States.
Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany.
Chem Res Toxicol. 2015 Jan 20;28(1):103-15. doi: 10.1021/tx500380t. Epub 2015 Jan 5.
Following oral administration of empagliflozin (1000 mg/kg/day) to male and female CD-1 mice for 2 years, renal tubular injury was identified in male mice. Renal injury was not detected in male mice (≤300 mg/kg/day), in female mice (1000 mg/kg/day), or in male or female Han Wistar rats (700 mg/kg/day). Using transfected HEK293 cells and Xenopus oocytes, empagliflozin was found to be a substrate of various mouse and rat organic anion transporters (oat/Oat) and organic anion transporting polypeptide (oatp/Oatp) transporters: mouse oat3, rat Oat3, mouse oatp1a1, and rat Oatp1a1. However, using isolated kidney slices from male and female mice and rats, no sex-based difference in the extent of uptake of empagliflozin occurred. Metabolism studies using hepatic and renal microsomes from male and female mice, rats, and humans revealed a hemiacetal metabolite of empagliflozin (M466/2), predominantly formed in male mouse kidney microsomes. Formation of M466/2 in male mouse kidney microsomes was 31-fold higher compared to that in female mouse kidney microsomes and was ∼29- and ∼20-fold higher compared to that in male and female mouse liver microsomes, respectively. M466/2 is unstable and degrades to form a phenol metabolite (M380/1) and 4-hydroxycrotonaldehyde (4-OH CTA). Formed 4-OH CTA was trapped by reduced GSH, and the structure of the GSH adduct was confirmed by mass spectrometry. Stoichiometric formation of M380/1 from M466/2 was observed (93-96% at 24 h); however, formation of 4-OH CTA was considerably lower (∼17.5% at 40 h), which is consistent with 4-OH CTA being a highly reactive species. These data represent a highly selective tissue-, species-, and sex-specific lesion in male CD-1 mice associated with a cytotoxic metabolite product, 4-OH CTA. In humans, glucuronidation of empagliflozin is the most prevalent metabolic pathway, and oxidation is a minor pathway. Thus, renal toxicity due to the formation of 4-OH CTA from empagliflozin is not expected in humans.
对雄性和雌性CD-1小鼠口服恩格列净（1000毫克/千克/天），持续2年，结果在雄性小鼠中发现了肾小管损伤。在雄性小鼠（≤300毫克/千克/天）、雌性小鼠（1000毫克/千克/天）或雄性和雌性Han Wistar大鼠（700毫克/千克/天）中均未检测到肾损伤。利用转染的HEK293细胞和非洲爪蟾卵母细胞，发现恩格列净是多种小鼠和大鼠有机阴离子转运体（oat/Oat）及有机阴离子转运多肽（oatp/Oatp）转运体的底物：小鼠oat3、大鼠Oat3、小鼠oatp1a1和大鼠Oatp1a1。然而，使用雄性和雌性小鼠及大鼠的离体肾切片，未观察到恩格列净摄取程度存在基于性别的差异。利用来自雄性和雌性小鼠、大鼠及人类的肝微粒体和肾微粒体进行的代谢研究显示，恩格列净有一个半缩醛代谢物（M466/2），主要在雄性小鼠肾微粒体中形成。雄性小鼠肾微粒体中M466/2的形成量比雌性小鼠肾微粒体中的高31倍，分别比雄性和雌性小鼠肝微粒体中的高约29倍和约20倍。M466/2不稳定，会降解形成酚类代谢物（M380/1）和4-羟基巴豆醛（4-OH CTA）。生成 的4-OH CTA被还原型谷胱甘肽捕获，谷胱甘肽加合物的结构通过质谱法得以确认。观察到从M466/2按化学计量形成M380/1（24小时时为93 - 96%）；然而，4-OH CTA的形成量要低得多（40小时时约为17.5%），这与4-OH CTA是一种高反应性物质相符。这些数据表明，在雄性CD-1小鼠中存在一种与细胞毒性代谢产物4-OH CTA相关的高度选择性的组织、物种和性别特异性损伤。在人类中，恩格列净的葡萄糖醛酸化是最主要的代谢途径，氧化是次要途径。因此，预计恩格列净不会在人类中因形成4-OH CTA而导致肾毒性。
