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Ketamine is a novel treatment for depression which has not responded to other treatments. A rapid antidepressant effect has been demonstrated in several clinical trials of single intravenous infusions over the last 15 years in patients with depression with has not responded to at least 2 or 3 antidepressants.

The response lasts a day for about 70% of patients and up to three days for 30% of patients. In some cases this benefit is longer: up to four months, following three infusions over three weeks. The majority of patients relapse within two weeks after treatment.

Oxford Health NHS Foundation Trust’s ketamine service is based at Warneford Hospital, Oxford.

The best evidences comes from a trial in which patients were randomly allocated to a dummy treatment which was thought would probably not work for depression (midazolam) or to ketamine. After seven days, four out of 25 (16%) patients who had been given midazolam infusion were responders compared with 21 out of 47 (47%) who had received the ketamine infusion.

It is important to recognise that ketamine is not licensed as an antidepressant. It has not been evaluated in large, or long term, clinical trials. There is much that is not known about how, or for whom, it works.

Large trials of the closely related drug esketamine, which is a component of ketamine, have shown broadly similar effects. A safety study of over 800 patients who took intranasal esketamine and a newly initiated antidepressant showed a 43% remission rate at 12 months.

Last updated: 29 October, 2018