In this latest study, British researchers have found that ketamine may help people whose depression is otherwise untreatable.

Ketamine has commonly been known as a party drug. But it could help some people who have severe depression. So say British researchers, who tested the drug in a new study.

The study, which was published in the Journal of Psychopharmacology, used ketamine intravenous infusions in people with treatment-resistant depression (TRD). The study was conducted in an NHS clinic by researchers at Oxford Health NHS Foundation Trust and Oxford University.

In the study, 28 patients with uni- or bipolar TRD were treated over a period of three weeks. They received either three or six ketamine infusions for 40 minutes in the recovery room of a routine ECT clinic. Memory tests were carried out a few days after the final infusion. Patients relayed their mood symptoms on a daily basis by text or email.

In some cases, the antidepressant response took a second ketamine infusion to become noticeable. But three days after the last infusion, the depression scores had halved in 29 percent of the patients. In patients who responded to the treatment, the benefit lasted between 25 days and eight months (the median was 2.3 months).

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Dr. Rupert McShane, a consultant psychiatrist at Oxford Health and a researcher in Oxford University’s Department of Psychiatry, said in a press statement that researchers saw remarkable changes in people who suffered from severe depression for many years, and who had been unaffected by other treatments.

One of the interesting findings was that patients reported that the flow of their thinking felt suddenly freer. “For some, even a brief experience of response helps them to realize that they can get better, and this gives hope,” said McShane.

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“Ketamine is a promising new antidepressant which works in a different way to existing antidepressants…. We especially wanted to check that repeated infusions didn’t cause cognitive problems,” McShane added in the press statement.

Although many patients relapsed within a day or two, 29 percent had benefits that lasted at least three weeks, and 15 percent took more than two months to relapse.

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When administered up to half a dozen times, ketamine did not cause cognitive or bladder side effects. However, some people did have side effects, such as anxiety during the infusion, or were sick. Over 400 infusions to 45 patients have been given by the research team, in their effort to find ways to maintain the drug’s effect.

In a separate study, on serial infusions of low-dose ketamine for major depression, Keith G. Rasmussen and researchers found that ketamine infusions at a lower rate than previously reported demonstrated similar efficacy and excellent tolerability and may be more practically available for routine clinical care. “Serial ketamine infusions appear to be more effective than a single infusion. Further research to test relapse prevention strategies with continuation ketamine infusions is indicated,” said the researchers.

McShane said that intravenous ketamine is an inexpensive drug that has a dramatic, but often short-term, effect in some patients who suffer from chronic severe depression. He said that more clinical experience with ketamine in a small number of carefully monitored patients is needed. “By trying different infusion regimes and adding other licensed drugs, we hope to find simple ways to prolong its dramatic effect,” McShane said.

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