SAN FRANCISCO—Ketamine, an anesthetic and illegal street drug, is also a quick and effective therapy for people with treatment-resistant depression, researchers announced Monday. 

In the largest clinical trial to date, researchers were able to demonstrate the effects of ketamine in people with difficult-to-treat mood disorders. Unlike most treatments, which can take several weeks to become effective, a single dose of ketamine begins working in as little as 24 hours.

Dr. James Murrough, an assistant professor at the Icahn School of Medicine at Mount Sinai Hospital, announced the research findings at the American Psychiatric Association’s annual conference. 

Murrough said that the doses used in clinical trials were tens to hundreds of times lower than those typically taken by recreational users, and that ketamine is “exceedingly safe” when used in small doses under medical supervision.

Testing the Effects of Ketamine on Treatment-Resistant Depression

At Mount Sinai, Murrough and colleagues recruited 73 patients with treatment-resistant depression. Patients were given a single injected dose of ketamine or midazolam, a drug with similar anesthetic effects to ketamine but without the antidepressant qualities.

Patients were interviewed 24 hours after the dose and again after two, three, and seven days. Researchers found that all the patients given ketamine were still experiencing antidepressant effects one week later. 

Murrough said that while the results of his research and other studies like it are promising, the treatment is “not ready for prime time” because the long-term effects of ketamine treatment are still unknown. 

“I think for now we have to wait for the research,” he said.

Ketamine continues to show promise in clinical trials, especially for patients with treatment-resistant depression.

A study conducted last year at Yale University and the National Institutes of Mental Health, published in the journal Science, showed similar results. That study demonstrated ketamine's antidepressant effects and revealed that the drug can reverse deficits in brain synapses caused by stress. 

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