Discipline of Psychiatry, Adelaide Medical School, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, South Australia, Australia.
3 papers in the library · 5 citations · publishing 2025-2026
Anxiety disorders and treatment-resistant major depressive disorder (TRD) often occur together. In a randomized controlled trial comparing subcutaneous ketamine to midazolam in 174 people with TRD, ketamine reduced anxiety only when given at flexible, response-guided doses (0.5-0.9 mg/kg). At a fixed low dose (0.5 mg/kg), the reduction in anxiety was not statistically significant. The anxiety-reducing effect was linked to overall depression improvement and was not sustained four weeks after treatment ended. The findings suggest that adequate dosing is necessary for ketamine's anxiolytic effect in this population.
Subcutaneous ketamine appears cost-effective for treatment-resistant depression from a health sector perspective when the costs of the control treatment (midazolam) are included, but not from a societal perspective. A cost-utility analysis alongside a randomized controlled trial with 174 participants compared ketamine to midazolam given twice weekly for four weeks. At the end of the trial, quality of life scores were significantly higher for ketamine. When control arm costs were included, ketamine was less costly and more effective, with an 89% probability of being cost-effective at a $50,000 per quality-adjusted life year threshold. Excluding those costs made ketamine not cost-effective, highlighting the importance of comparator choice.
Ketamine's effect on suicidal ideation in adults with treatment-resistant depression remains uncertain. In a phase III double-blind randomized trial comparing subcutaneous racemic ketamine to midazolam over four weeks, one cohort showed no significant difference between groups on either the MADRS item 10 or the C-SSRS measure of suicidal ideation. A second cohort showed a non-significant reduction on the MADRS item 10 but a significant reduction on the C-SSRS. Baseline suicidal ideation scores were low in both cohorts. Adverse events requiring clinical review occurred in 13.8% of all treatment sessions. The authors suggest flexible-dose subcutaneous racemic ketamine may have beneficial effects on suicidal ideation scores, but future studies need to be powered for suicidal ideation as a primary outcome.