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    'Club Drug' May Fight Depression

    Study Shows Ketamine May Provide Fast-Acting Depression Relief

    WebMD Health News
    Reviewed by Louise Chang, MD

    Aug. 7, 2006 -- Low doses of ketamine, a medication used as an anesthetic in humans and animals, relieves depression in just two hours and the effect may last as long as a week, new research shows.

    Ketamine is also sometimes abused as a "club drug." Known in slang as "special K," it can cause hallucinations and euphoria in higher doses.

    According to a study in the August issue of the Archives of General Psychiatry, researchers tested 18 adult men and women diagnosed with depression who had failed at least two antidepressant regimens. None of the participants had a current substance abuse problem at the time of the study.

    They were first tested with a one-time dose of intravenous ketamine or plain saline. Then a week later, the ketamine group got a dose of saline, and the saline group got a dose of ketamine.

    Quick Results

    Within an hour and a half after the injection, those who received the ketamine had improvement of their depression -- with effects lasting for a week.

    By contrast, current antidepressants, including the popular selective serotonin reuptake inhibitors (SSRIs) -- such as Prozac and Paxil -- can take weeks or months to kick in.

    One day after the ketamine injection, 71% of participants responded with 50% or greater improvement on a standard scale used to measure depression and 29% met the criteria for remission. For 35%, the improved effects lasted through the week, the study showed.

    While the new results may not apply to all groups of depressed people, "there is no treatment for depression that works this rapidly and dramatically with a single administration," researcher Carlos Zarate Jr., MD, tells WebMD. Zarate is the chief of the mood disorders research unit at the National Institute of Mental Health (NIMH) in Bethesda, Md.

    Exactly how the anesthetic relieves depression is not fully understood, but animal studies have suggested that blocking a brain chemical receptor called the N-methyl-D-aspartate (NMDA) receptor can reduce depression-like behaviors. Ketamine blocks the NMDA receptor.

    In its simplest terms, ketamine hits the cascade of brain chemicals that causes depression closer to home than available antidepressants, he says. "If you had a leaky faucet, we start in the kitchen at the source of the leak, [the NMDA receptor], while other antidepressants may begin at the water processing plant, [the serotonin and other brain chemicals believed to play a role in depression]," he explains. "We can localize it to right where the leak is, so we don't have to be satisfied anymore with not getting results for weeks to months," he says.

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