Low-dose ketamine infusion in treatment-resistant double depression: Revisiting the adjunctive ketamine study of Taiwanese patients with treatment-resistant depression.

Abstract

Whether a single low-dose ketamine infusion may have rapid antidepressant and antisuicidal effects in patients with treatment-resistant double depression remains unclear. This study enrolled 35 patients with treatment-resistant double depression, 12 of whom received 0.5mg/kg ketamine, 11 received 0.2mg/kg ketamine, and 12 received normal saline as a placebo. The patients were assessed using the 17-item Hamilton Rating Scale for Depression (HDRS) prior to the initiation of infusions, at 40 and 240min post-infusion, and sequentially on Days 2-7 and on Day 14 after ketamine or placebo infusions. A single 0.5mg/kg ketamine infusion had rapid antidepressant (p=0.031, measured by the HDRS) and antisuicidal (p=0.033, measured by the HDRS item 3 scores) effects in patients with treatment-resistant double depression. However, 0.2mg/kg ketamine was insufficient to exert rapid antidepressant and antisuicidal effects in this patient population with severe and chronic illness. In this patient population, the commonly used dose of 0.5mg/kg was sufficient. Additional studies are required to investigate whether repeated infusions of low-dose ketamine may also maintain antidepressant and antisuicidal effects in patients with treatment-resistant double depression.