A single subanesthetic dose of intravenous ketamine reduced explicit suicidal thoughts and implicit associations between self and escape in adults with treatment-resistant major depression more than the active placebo midazolam. Twenty-four hours after infusion, 53% of ketamine-treated patients scored zero on all three explicit suicide measures, compared with 24% of the midazolam group. The reductions in explicit suicidal cognition were largest in those with higher baseline suicidal thoughts and were partly explained by decreases in other depressive symptoms. The findings suggest ketamine may offer rapid relief from suicidal cognition beyond what a psychoactive placebo provides.
A single infusion of ketamine, compared to midazolam as an active placebo, did not reduce suicidal ideation scores on the Beck Scale for Suicidal Ideation at 24 hours in patients with mood and anxiety disorders who were at elevated risk for suicidal behavior. A significant difference favoring ketamine emerged at 48 hours, but the effect was no longer significant by the end of 7 days. The intervention was well tolerated with no dropouts during the primary assessment period. The findings support the safety and tolerability of ketamine for suicidal ideation but larger studies are needed.
A combination of dextromethorphan and quinidine, given at up to 45/10 mg twice daily for 10 weeks, reduced depression scores in patients with treatment-resistant depression. Twenty patients with unipolar treatment-resistant depression enrolled; six discontinued early. Depression scores on the Montgomery-Asberg Depression Rating Scale dropped by an average of 13 points, and on the Quick Inventory of Depressive Symptomatology by nearly 6 points. Response and remission rates were 45% and 35%, respectively. No treatment-emergent suicidal thoughts, psychosis, or dissociation occurred. The open-label, proof-of-concept design limits conclusions, but results suggest the combination is tolerable and warrants larger placebo-controlled trials.