The anesthetic ketamine, used in both humans and animals, is perhaps best known as an illegal party drug due to its hallucinogenic effects. However, a growing body of research indicates that the drug may have a powerful new medical use: as a fast-acting antidepressant without the side effects seen in most prescription antidepressants.
As Naturereports, in many clinical trials to date people who have not responded to standard antidepressant treatment — such as SSRIs including Prozac — seem to respond to ketamine. And while it can take weeks to feel better after starting a prescription antidepressant, the therapeutic effects of ketamine are seen in a matter of hours.
Despite the seemingly “miracle drug” nature of ketamine, there are serious concerns about its use in depression. First, it is unclear how the drug works to alleviate depression. Second, there are no long-term studies on its long-term use. Studies that have already been done indicate the antidepressant effects of ketamine can last from between a few days to a few weeks.
And due to the addictive nature of ketamine itself, there are worries that sustained use of it may lead to dependence.
On May 4, Nature published the results of the latest trialinvolving ketamine, bolstering its potential as an antidepressant treatment. Researchers, examining the drug in mice, found that that the mood boosting effects may not be caused by ketamine itself, but instead by one of the metabolites ((2R,6R)-hydroxynorketamine) formed when the drug is broken down into smaller pieces.
Even more promising, the ketamine given to the rats did not increase side effects, even though the dose was much stronger than what would be given to humans for depression. The researchers say they want to take the metabolite into testing in humans, though that is likely years away.
The largest trialever of ketamine in depression was done in 2013 with 73 participants. The drug lead to a decline in depression symptoms 24 hours after treatment in 64% of patients, all of whom had tried at least 3 other drugs without any results.
Despite the lack of clear-cut evidence of its benefits and unknowns about its long-term risk, many doctors are already offering ketamine as a depression treatments to patients, though this is an off-label use.
Side effects of ketamine can include confusion, lucid daydreaming, fuzzy vision, and a “high” feeling, though they tend to go away quickly, according to these doctors. Patients, who are usually given ketamine via infusion, are carefully monitored and must have pre-arranged transport home. They can’t drive or use heavy machinery for 24 hours.
Drug companies are even trying to cash in on the ketamine craze. Janssen Pharmaceutical is testing a form of ketamine it developed, called esketamine, in 5 clinical trials. It would be given via a nasal spray. Another is rapastinel, under development by Allergan. Both drugs had “breakthrough therapy designation” from the FDA, meaning they will go through the regulatory process at a much quicker rate.