ABSTRACT
WHAT IS KNOWN AND OBJECTIVE: Some patients with refractory depression who fail to respond to rapid injection of standard-dose ketamine are injected with high doses, but the safety and efficacy of this practice are unclear. CASE DESCRIPTION: A 57-year-old woman with refractory depression whose symptoms did not improve after 20-seconds intravenous injection of 0.5 mg/kg ketamine went into remission following eight, 1-minute intravenous injections of 1 mg/kg ketamine delivered over a 4-week period. By 6-month follow-up, no significant adverse events had occurred and cognitive function had improved. WHAT IS NEW AND CONCLUSION: High-dose intravenous injections of ketamine may stably improve depressive symptoms and cognitive function in patients with refractory depression who do not respond to rapid intravenous injection of standard-dose ketamine. The high-dose treatment appears to be associated with only mild side effects.