Ketamine, a prescription drug used as an anesthetic -- and used illegally as a party drug at raves -- may have a role in treating people with bipolar depression, according to a study released Monday.

Previous research has shown that ketamine can have a rapid effect on depression. The new study featured 18 people with bipolar depression, an illness in which bouts of severe depression alternate with periods of mania or excessively high energy. Bipolar depression is particularly difficult to treat; only one drug is approved specifically for the illness and patients often try a mixture of several psychiatric medications to quell symptoms. Successful, swift treatment is important, however, because the suicide rate among patients is among the highest of any mental disorder.

In the study, researchers at the National Institute of Mental Health found that 71% of the bipolar patients who had not responded to other treatments, experienced significant improvement in depression symptoms after a single intravenous infusion of ketamine. Most of these patients responded within 40 minutes of receiving the drug. In comparison, 6% of the patients receiving a placebo responded positively.

The effects of ketamine lasted about three days. Earlier studies of people with depression showed an average duration of seven days from ketamine therapy.

The ketamine studies have yielded some interesting information about the possible causes of depression and bipolar depression. The drug is an N-methyl-D-aspartate-receptor antagonist, which means it acts on neurotransmitters in the brain that are part of the glutamatergic system. Future studies should explore this pathway as well as test ideas to increase the length of the response from ketamine, the authors said.

“Rapid-onset pharmacological strategies with pronounced and sustained effects would have an enormous impact on publich health,” they wrote.

The study appears in the Archives of General Psychiatry.

-- Shari Roan

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