By Katrina Woznicki
WebMD Health News
Reviewed by Laura J. Martin, MD
Aug. 2, 2010 -- Patients with bipolar disorder who failed to find relief from their depression with other standard treatments experienced fast-acting relief from a single intravenous (IV) dose of a drug called ketamine, according to a new, small study.
Researchers at the National Institute of Mental Health in Bethesda, Md., found that ketamine, an anesthetic, improved symptoms of depression within 40 minutes of injection. The beneficial effects remained significant one day and even two days after the injection, suggesting that ketamine was both fast-acting and long-lasting, the authors report in the August issue of Archives of General Psychiatry.
These results are noteworthy, the researchers say, since patients often experience a long lag between the time they take their depression treatment to the time they feel an improvement in their mood. Overall, 71% of the patients responded to the ketamine and reported an improvement in symptoms, compared with 6% of patients given a placebo.
Slideshow: Bipolar Disorder Overview
Ketamine and Bipolar Depression
It has been challenging to find treatments for bipolar disorder because scientists do not fully understand the condition. However, recent research suggested the brain's glutamatergic system, which plays a role in information processing and memory, may be involved in bipolar disorder. Ketamine affects this system and may have potential as a new treatment, the researchers explain.
The research team studied 18 patients between the ages of 18 and 65 who had failed to respond to other common treatments for bipolar disorder. The patients were randomly assigned to receive either a single dose of ketamine or a placebo between October 2006 and June 2009. The patients had taken either valproate or lithium -- two standard treatments for bipolar depression -- without success prior to beginning the study.
During the study, patients did not participate in any psychotherapy, but they did continue to take valproate or lithium and were not allowed to receive any other depression drugs.
Two weeks after the first injection, the researchers switched the groups and gave them the treatment they did not receive during the first round. There were no serious side effects.
These findings are particularly noteworthy because a large number of the participants had been prescribed complex treatment regimens in the past with substantial failures, the authors write.
"The mean number of past antidepressant trials was seven, and more than 55 percent of participants failed to respond to electroconvulsive therapy. The toll of this protracted and refractory illness on the subjects was evident, in that two-thirds of participants were on psychiatric disability and nearly all were unemployed."
"Future studies should examine strategies for long-term maintenance of ketamine's rapid antidepressant response," the authors conclude.
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News release, Archives of General Psychiatry.
Diazgranados, N. Archives of General Psychiatry; August 2010; vol 67: pp 793-802.
National Institute of Mental Health.
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