Repeated administration of subanesthetic intravenous ketamine may prolong the rapid decrease in suicidal ideation (SI) elicited by single infusions. The purpose of this secondary analysis was to evaluate reduction in SI with a single ketamine infusion compared with an active control, and prolonged suppression of SI with repeated and maintenance infusions. Thirty-seven participants with treatment-resistant depression (TRD) and baseline SI first received a single ketamine infusion during a randomized, double-blind crossover with midazolam. Following relapse of depressive symptoms, participants received six open-label ketamine infusions administered thrice-weekly over 2 weeks. Antidepressant responders (≥50% decrease in Montgomery-Åsberg Depression Rating Scale [MADRS] scores) received four further open-label infusions administered once-weekly. Changes in SI were assessed with the suicide items on the MADRS (item 10, MADRS-SI) and the Quick Inventory of Depressive Symptomatology-Self Report (item 12, QIDS-SI). Linear mixed models revealed that compared with midazolam, a single ketamine infusion elicited larger reduction in SI (P = 0.01), with maximal effects measured at 7 days postinfusion (P < 0.001, Cohen's d = 0.83). Participants had cumulative reductions in MADRS-SI scores with repeated infusions (P < 0.001), and no further change with maintenance infusions (P = 0.94). QIDS-SI results were consistent with MADRS-SI. Overall, 69% of participants had a complete alleviation of SI following repeated infusions. In TRD, single and repeated ketamine infusions resulted in decreases in SI which were maintained with once-weekly maintenance infusions. This study adds to the growing body of research suggesting ketamine as a possible novel treatment strategy for SI in mood disorders.

中文翻译：

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单次和重复氯胺酮输注可减少难治性抑郁症的自杀意念。

重复施用亚麻醉静脉氯胺酮可能会延长单次输注引起的自杀意念（SI）的迅速下降。该次要分析的目的是评估与有效对照组相比，单次氯胺酮输注可降低SI，并通过反复输注和维持输注来长期抑制SI。37名抗抑郁治疗（TRD）和基线SI的参与者在与咪达唑仑的随机双盲交叉治疗中首先接受了氯胺酮单次输注。抑郁症状复发后，参与者在两周内每周三次接受六次开放标签的氯胺酮输注。抗抑郁药的应答者（蒙哥马利-奥斯伯格抑郁量表[MADRS]得分降低了50％以上）每周接受一次四次开放标签输注。用MADRS上的自杀项目（项目10，MADRS-SI）和抑郁症症状自我快速调查表（项目12，QIDS-SI）评估SI的变化。线性混合模型显示，与咪达唑仑相比，单次氯胺酮输注引起SI的更大降低（P = 0.01），并且在输注后7天测得的最大影响（P <0.001，Cohen d = 0.83）。重复输注的参与者MADRS-SI分数累积下降（P <0.001），维持输注的参与者无进一步变化（P = 0.94）。QIDS-SI结果与MADRS-SI一致。总体而言，重复输注后有69％的参与者完全缓解了SI。在TRD中，单次和重复的氯胺酮输注会导致SI降低，而每周一次的维持输注可维持SI的降低。