Treatment of Bipolar Disorder - NMDA-receptor Antagonists

NMDA-receptor Antagonists

In a double-blind, placebo-controlled, proof-of-concept study, researchers administered an N-methyl-d-aspartate–receptor antagonist (ketamine) to 18 patients already on treatment with lithium (10 patients) or valproate (8 patients) for bipolar depression. From 40 minutes following intravenous injection of ketamine hydrochloride (0.5 mg/kg), the researchers observed significant improvements in depressive symptoms, as measured by standard tools, that were maintained for up to 3 days, an effect not observed in subjects who received the placebo. Five subjects dropped out of the ketamine study; of these, four were taking valproate and one was being treated with lithium. One patient showed signs of hypomania following ketamine administration and two experienced low mood. This study demonstrates a rapid-onset antidepressant effect of ketamine in a small group of patients with bipolar depression. The authors acknowledged the study's limitations, including the dissociative disturbances in patients receiving ketamine that could have compromised the study blinding, and they emphasised the need for further research.

A more recent double-blind, placebo-controlled study by the same group found that ketamine treatment resulted in a similarly rapid alleviation of suicidal ideation in 15 patients with bipolar depression.

Ketamine is used as a dissociative anaesthetic, and is a Class C substance in the United Kingdom; as such, it should only be used under the direction of a health professional.