Himmelseher S, Pfenninger E
Institut für Anästhesiologie, Klinikum rechts der Isar, Technische Universität.
Anasthesiol Intensivmed Notfallmed Schmerzther. 1998 Dec;33(12):764-70. doi: 10.1055/s-2007-994851.
The intravenous anaesthetic ketamine is a racemic mixture of two equimolar doses of enantiomers. After stereoselective separation, the right-handed S(+)-isomer is now clinically available. Since anaesthetic and analgesic pharmacological studies have shown that S(+)-ketamine is approximately two times as potent as racemic ketamine, the clinical effects of S(+)-ketamine were evaluated in comparison to ketamine-racemate at dose relation of 1:2 in several therapeutic investigations. The studies disclosed that both drugs caused a similar activation of the endocrine stress response and a comparable stimulation of the sympathoadrenergic system. However, application of S(+)-ketamine was associated with a remarkably smoother emergence period, a profound postoperative analgesia, a more rapid recovery of cerebral functions, and a greater preference by the study persons. The incidence of psychotomimetic phenomena appeared to be negligibly less after S(+)-ketamine in comparison to racemic ketamine, but their quality was described as far less unpleasant. Clinical use of S(+)-ketamine administered at one-half of the usual dose is thus not only associated with a reduction of undesirable adverse effects without altering ketamine's anaesthetic and analgesic potency, but also offers distinctive improvements due to the reduced drug load. Moreover, increasing experimental evidence supports a remarkable neuroprotective effect of S(+)-ketamine, which may become a promising drug for new therapeutic approaches to neuroprotection.
静脉麻醉药氯胺酮是两种对映体等摩尔剂量的外消旋混合物。经过立体选择性分离后，右旋S(+)-异构体现已可用于临床。由于麻醉和镇痛药理学研究表明，S(+)-氯胺酮的效力约为外消旋氯胺酮的两倍，因此在多项治疗研究中，以1:2的剂量关系将S(+)-氯胺酮与消旋氯胺酮进行比较，评估了S(+)-氯胺酮的临床效果。研究发现，两种药物都会引起类似的内分泌应激反应激活和对交感肾上腺素能系统的类似刺激。然而，使用S(+)-氯胺酮的苏醒期明显更平稳，术后镇痛效果更显著，脑功能恢复更快，且受试者更倾向于使用。与消旋氯胺酮相比，S(+)-氯胺酮后拟精神病现象的发生率似乎微不足道地降低了，但其程度被描述为远没有那么令人不适。因此，以通常剂量的一半使用S(+)-氯胺酮进行临床应用，不仅可以在不改变氯胺酮麻醉和镇痛效力的情况下减少不良副作用，还由于药物负荷降低而带来显著改善。此外，越来越多的实验证据支持S(+)-氯胺酮具有显著的神经保护作用，这可能使其成为神经保护新治疗方法的一种有前景的药物。
