A 12-month naturalistic observation of three patients receiving repeat intravenous ketamine infusions for their treatment-resistant depression

BackgroundAcute administration of subanesthestic doses of intravenous ketamine have been shown to elicit a rapid antidepressant response in patients with treatment-resistant depression. However, it remains to be seen if repeated doses over a longer period of time will have the same effects. Here, we assess the long-term efficacy of repeated intravenous ketamine infusions in three patients with high treatment-resistant depression via a naturalistic observation study.MethodThree patients consented to intravenous ketamine infusions as a therapy for their treatment-resistant depression. Patients were administered ketamine at 0.5 mg/kg of ideal body weight over 40 min followed by a saline flush until discharge. Severity of depressive symptoms was rated with the Montgomery-Asberg Depression Rating Scale.ResultsAll three patients responded to the ketamine infusions, but each went through an individualized course of treatment based on their own response.LimitationsThis was an open-label naturalistic observation without blinding, randomization, or a placebo control.ConclusionsThese cases add to the literature supporting the therapeutic effect of low-dose repeated intravenous ketamine for patients with treatment-resistant depression. Further study is needed to define the risks, benefits, indications, and contraindications of this potential treatment.