New research suggests that just one dose of the anesthetic ketamine appears to reduce depression in patients who show little improvement with standard medications.
Researchers say the beneficial effects start less than 2 hours after the drug is given and last for about 7 days.
According to a study by researchers at the National Institutes of Health in Bethesda, Maryland, most existing treatments for depression can take weeks or months to relieve people's symptoms and any treatment which provides an antidepressant effect during this lag time would be of major benefit.
Dr. Carlos A. Zarate, Jr, and his team looked at ketamine as a possible treatment because it blocks an enzyme system that seems to play a key role in depression.
For the research the team studied a group which included 17 patients with severe depression who had not responded to at least two trials of antidepressants.
The participants were required to have a score of at least 18 on a standard depression test called the Hamilton Depression Rating Scale (HDRS).
In the trial, the patients were given an intravenous infusion of ketamine or an inactive "placebo," then switched to an infusion of the other agent one week later.
In order to assess the onset and duration of effect, Zarate and his team used the HDRS an hour before the infusion, and at 40, 80, 110, and 230 minutes afterwards, then on days 1, 2, 3, and 7 days.