Context Existing therapies for bipolar depression have a considerable lag of onset of action. Pharmacological strategies that produce rapid antidepressant effects—for instance, within a few hours or days—would have an enormous impact on patient care and public health. Objective To determine whether an N-methyl-d-aspartate–receptor antagonist produces rapid antidepressant effects in subjects with bipolar depression. Design A randomized, placebo-controlled, double-blind, crossover, add-on study conducted from October 2006 to June 2009. Setting Mood Disorders Research Unit at the National Institute of Mental Health, Bethesda, Maryland. Patients Eighteen subjects with DSM-IV bipolar depression (treatment-resistant). Interventions Subjects maintained at therapeutic levels of lithium or valproate received an intravenous infusion of either ketamine hydrochloride (0.5 mg/kg) or placebo on 2 test days 2 weeks apart. The Montgomery-Asberg Depression Rating Scale was used to rate subjects at baseline and at 40, 80, 110, and 230 minutes and on days 1, 2, 3, 7, 10, and 14 postinfusion. Main Outcome Measures Change in Montgomery-Asberg Depression Rating Scale primary efficacy measure scores. Results Within 40 minutes, depressive symptoms significantly improved in subjects receiving ketamine compared with placebo (d=0.52, 95% confidence interval [CI], 0.28-0.76); this improvement remained significant through day 3. The drug difference effect size was largest at day 2 (d=0.80, 95% CI, 0.55-1.04). Seventy-one percent of subjects responded to ketamine and 6% responded to placebo at some point during the trial. One subject receiving ketamine and 1 receiving placebo developed manic symptoms. Ketamine was generally well tolerated; the most common adverse effect was dissociative symptoms, only at the 40-minute point. Conclusion In patients with treatment-resistant bipolar depression, robust and rapid antidepressant effects resulted from a single intravenous dose of an N-methyl-d-aspartate antagonist. Trial Registration clinicaltrials.gov Identifier: NCT00088699
The N-methyl-D-aspartate antagonist ketamine has rapid antidepressant effects in patients with treatment-resistant major depression (TRD); these effects have been reported to last for 1 week in some patients. However, the extent and duration of this antidepressant effect over longer periods has not been well characterized under controlled conditions. Riluzole, a glutamatergic modulator with antidepressant and synaptic plasticity-enhancing effects, could conceivably be used to promote the antidepressant effects of ketamine. This study sought to determine the extent and time course of antidepressant improvement to a single-ketamine infusion over 4 weeks, comparing the addition of riluzole vs placebo after the infusion. Forty-two subjects (18-65) with TRD and a Montgomery-Asberg Depression Rating Scale (MADRS) score of ≥ 22 received a single intravenous infusion of ketamine (0.5 mg/kg). Four to six hours post-infusion, subjects were randomized to double-blind treatment with either riluzole (100-200 mg/day; n=21) or placebo (n=21) for 4 weeks. Depressive symptoms were rated daily. A significant improvement (P<0.001) in MADRS scores from baseline was found. The effect size of improvement with ketamine was initially large and remained moderate throughout the 28-day trial. Overall, 27% of ketamine responders had not relapsed by 4 weeks following a single ketamine infusion. The average time to relapse was 13.2 days (SE=2.2). However, the difference between the riluzole and placebo treatment groups was not significant, suggesting that the combination of riluzole with ketamine treatment did not significantly alter the course of antidepressant response to ketamine alone.
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