CONCLUSIONS
TRD, depressive, ideation
In summary, our study results support the rapid antidepressant and antisuicidal effects of low-dose ketamine infusion on patients with TRD and prominent suicidal ideation. The antidepressant effect of ketamine persisted for up to 2 weeks, but the antisuicidal effect lasted only 5 days. In addition, timing of ketamine treatment is crucial; specifically, patients with moderate or low treatment refractoriness, current depressive episodes that have persisted <24 months, or ≤4 failed antidepressant treatments may receive the greatest benefits from low-dose ketamine infusion.