The chiral drug ketamine has long-lasting antidepressant effects with a fast onset and is also suitable to treat patients with therapy-resistant depression. The metabolite hydroxynorketamine (HNK) plays an important role in the antidepressant mechanism of action. Hydroxylation at the cyclohexanone ring occurs at positions 4, 5, and 6 and produces a total of 12 stereoisomers. Among those, the four 6HNK stereoisomers have the strongest antidepressant effects. Capillary electrophoresis with highly sulfated γ-cyclodextrin (CD) as a chiral selector in combination with mass spectrometry (MS) was used to develop a method for the enantioselective analysis of HNK stereoisomers with a special focus on the 6HNK stereoisomers. The partial filling approach was applied in order to avoid contamination of the MS with the chiral selector. Concentration of the chiral selector and the length of the separation zone were optimized. With 5% highly sulfated γ-CD in 20 mM ammonium formate with 10% formic acid and a 75% filling the four 6HNK stereoisomers could be separated with a resolution between 0.79 and 3.17. The method was applied to analyze fractionated equine urine collected after a ketamine infusion and to screen the fractions as well as unfractionated urine for the parent drug ketamine and other metabolites, including norketamine and dehydronorketamine.

中文翻译：

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尿液中氯胺酮代谢物的对映选择性 CE-MS 分析

手性药物氯胺酮具有起效快、持续时间长的抗抑郁作用，也适用于治疗难治性抑郁症患者。代谢物羟基去甲氯胺酮 (HNK) 在抗抑郁作用机制中起重要作用。环己酮环的羟基化发生在 4、5 和 6 位，共产生 12 种立体异构体。其中，四种6HNK立体异构体的抗抑郁作用最强。使用高度硫酸化 γ-环糊精 (CD) 作为手性选择剂的毛细管电泳结合质谱 (MS) 开发了一种对映选择性分析 HNK 立体异构体的方法，特别关注 6HNK 立体异构体。应用部分填充方法是为了避免 MS 被手性选择器污染。优化了手性选择器的浓度和分离区的长度。在 20 mM 甲酸铵和 10% 甲酸中使用 5% 高度硫酸化的 γ-CD 和 75% 的填料，可以分离四种 6HNK 立体异构体，分辨率在 0.79 和 3.17 之间。该方法用于分析氯胺酮输注后收集的分馏马尿液，并筛选母体药物氯胺酮和其他代谢物（包括去甲氯胺酮和脱氢去甲氯胺酮）的馏分和未分馏尿液。