Ketamine Effective for Treatment-Resistant Depression, Study Finds

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A low-cost version of ketamine may improve outcomes in those with treatment-resistant depression, according to research published in the British Journal of Psychiatry.

The study, funded by the Australian National Health and Medical Research Council, was a collaboration between six academic clinical mood disorder units in Australia and one in New Zealand. For the investigation, researchers aimed to determine the efficacy of ketamine for treatment-resistant depression when compared with a placebo.

According to the study's authors, ketamine is widely used in the Australian medical system for anesthesia and sedation. Recently, research has indicated that ketamine may also help treat depression. However, the patented S-Ketamine nasal spray costs about $800 per dose, rendering the treatment inaccessible for most people. Generic ketamine, on the other hand, can cost as little as $5, making it a more viable treatment option for people with depression.

Involved in the study were 179 people with treatment-resistant depression. Participants received either an injection of a generic ketamine or a placebo twice a week for one month. After each dose, participants were monitored for approximately two hours while the acute dissociative and sedative effects wore off. Participants were asked to assess their mood at the end of the trial and again one month later.

The trial was double-blind, meaning neither the participants nor the administrators knew which who received the generic ketamine and who received the placebo. To further mask the treatments, researchers chose to administer another sedative called midazolam as the placebo.

"Because there are no subjective effects from the saline, in previous studies, it became obvious which people were receiving the ketamine and which people received placebo," said lead researcher Colleen Loo, MD, a professor at the University of New South Wales in Kensington, Australia. "In using midazolam, which is not a treatment for depression, but does make you feel a bit woozy and out of it, you have much less chance of knowing whether you have received ketamine, which has similar acute effects."

The study found that one-third of the participants who received ketamine improved their depression symptoms by at least 50 percent. In addition, 20 percent of those who received ketamine reported no longer having clinical depression compared to only two percent of people in the placebo group.

"For people with treatment-resistant depression, so those who have not benefitted from different modes of talk therapy, commonly prescribed antidepressants, or electroconvulsive therapy, 20 percent remission is actually quite good," said Loo.

To Loo, these results show promise for ketamine as an intervention for those with treatment-resistant depression. However, she noted that the effects of ketamine seem to wear off after a few days to a week, so it may have to be an ongoing treatment. Lou said for future studies, she and her team will study the effects of generic ketamine through larger trials over longer periods to assess the drug’s safety.