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Study: Ketamine infusions found safe, effective in treatment-resistant depression

A study found that in treatment-resistant depression up to six low-dose ketamine infusions can safely be given within an existing NHS clinical structure to patients who continue their antidepressants.

Treatment resistance was defined in the study as a current or past history or lack of response to two adequate antidepressant trials using the Antidepressant Treatment History Form.

The cohort was made up of 28 patients in an electroconvulsive therapy (ECT) treatment clinic with uni- or bipolar treatment-resistant depression.

Participants were administered three ketamine infusions in stage 1 or six infusions in stage 2, over a 3-week period at an IV dose of 0.5 mg/kg over 40 minutes.

On day 21, following the 3 weeks of treatment, participants completed a visual analogue scale, as well as tests to assess mood, memory and story recall. Follow up occurred at 2 weeks, 4 weeks, 8 weeks, 12 weeks and 26 weeks, with additional memory evaluations at 12 and 26 weeks. Eight patients did not complete all infusions for various reasons, including adverse reactions to treatment, failure to benefit and increased anxiety.

As for ketamine effects on participant mood, the mean reduction in Beck Depression Inventory scores at day 21 was 12.2 in stage 1 and 11 in stage 2, with average reductions of 23.4 and 31.7 from baseline. Researchers observed a reduction in suicide ideation in 61% of patients within 6 hours of receiving a single infusion.

Based on their findings, the researchers concluded that ketamine can safely be given to patients who remain on antidepressants. They also found no link between treatment and memory deficits when ketamine was given up to six times. Finally, they found that the ECT clinic was a safe and tolerated site for the treatment.

“Our experience raises the possibilities that its dramatic and useful antidepressant effect may require at least two infusions to become apparent and last longer if taken with other antidepressants, but clearly more work is needed to confirm this,” the researchers wrote.

Disclosure: The researchers report no relevant financial disclosures.