The anesthetic drug ketamine—also known as “Special K” when used as a street drug—relieved depressive symptoms in people with treatment-resistant bipolar disorder (BD) in as little as 40 minutes, according to a study published in the August 8 issue of the Archives of General Psychiatry and reported by the National Institutes of Mental Health (NIMH).

Ketamine is a powerful anesthetic and tranquilizer, but it also influences the neurotransmitter glutamate, which has been implicated in depression and BD. Ketamine has significant side effects, but previous studies have shown that it can rapidly reduce depressive symptoms. Thus, Nancy Diazgranados, MD, and her colleagues from the NIMH, studied the effects of the drug in 18 people with highly treatment-resistant BD.

In the study, half of the participants received an intravenous infusion of ketamine and the other half received a placebo. One week later, those who’d originally received ketamine got the placebo and vice versa.

Diazgranados and her colleagues found that 56 percent of those who received ketamine had at least a 50 percent reduction in depressive symptoms within 40 minutes, 13 percent became symptom free. The effects of the ketamine lasted about one week. In contrast, none of the patients receiving a placebo had the same degree of symptom reduction.

“The work adds to the evidence of the potential of medications targeting the glutamate system for rapid relief from depression, even in cases of people who have failed to respond to other existing therapies,” reported the NIMH. “Rapid and effective treatment of depression is an urgent public health need. BD can be disabling—nearly all the patients in this study were unemployed as a result of the severity of their illness. BD is among the psychiatric disorders with the highest risk of suicide.”

The NIMH concluded: “Continuing research is focusing on developing NMDA-targeting medications that are suitable for clinical use; and investigating the use of this class of drugs for long-term maintenance of the rapid antidepressant effect seen in this study.”