Intranasal racemic ketamine maintenance therapy for patients with treatment-resistant depression: a naturalistic feasibility study.

Background: Ketamine is a promising therapy for treatment-resistant depression due to its rapid onset, although benefits are often transitory, with patients needing maintenance therapy to prevent relapse. Most data supporting ketamine for treatment-resistant depression refers to the intravenous route of administration, leaving alternative routes lacking in data, especially as maintenance regimens. Moreover, the safety of ketamine maintenance therapy is poorly defined. This report aims to describe and evaluate a novel hospital-to-outpatient intranasal racemic ketamine maintenance therapy program.

Methods: This was an observational program evaluation study. Participants were adult inpatients with treatment-resistant depression who had been successfully treated with intranasal racemic ketamine in hospital and were being referred for outpatient maintenance therapy with an intranasal racemic ketamine spray, administered at a specialized community treatment centre. Effectiveness was assessed with the Self-Report Quick Inventory of Depressive Symptomatology, the Quality of Life Scale, and the Clinical Global Impression-Improvement scale.

Results: Five patients were enrolled, completing up to 14 treatment sessions over 192 days. The mean dose administered throughout treatment was 220 mg (100 to 400 mg). All patients had decreased (or stable) depressive symptoms and increased (or stable) quality of life. There were no serious adverse events or discontinuations due to adverse effects. Reported adverse effects included anxiety and nausea. Slight blood pressure increases were seen during treatment, none of which required intervention.

Conclusions: Intranasal racemic ketamine maintenance therapy for treatment-resistant depression appeared to be feasible and well tolerated, although effectiveness conclusions cannot be drawn from this small pilot study. Further investigations regarding the safety and effectiveness of intranasal ketamine maintenance therapy are warranted.