A drug originally developed as an antidepressant could ease withdrawal symptoms from opiate addiction, and make it easier to avoid relapse during treatment, according to a new study. Called rapastinel, the drug reversed signs of opiate withdrawal in rats in just three days, without many of the drawbacks of existing medications for opiate withdrawal, according to ScienceDaily.com.

Existing treatments like buprenorphine and methadone are opiates, and can be addictive in themselves. They also have dangerous side effects and often must be used for months at a time. They maintain the changes in the brain that first led to addiction.

Ketamine has also been suggested as a treatment alternative, but has a risk of its own dangerous side effects, including hallucinations.

Rapastinel, on the other hand, could be used to limit withdrawal symptoms and prevent relapse in the first days of treatment. It binds to the same receptor as ketamine, but at a different site, and has been well-tolerated in studies.

The drug was developed to treat depression by Naurex, which was acquired by Allergan for $560 million in 2015. Hopes for the success of rapastinel as an antidepressant were a centerpiece of the acquisition.

Recent trials failed to show it’s effective for treating depression, but have demonstrated that it has few side effects and is well-tolerated.

Julia Ferrante, an undergraduate at Villanova University who worked on the research with Duke pharmacology and cancer biology professor Cynthia M. Kuhn, explained:

“We have found that rapastinel has potential as a new treatment for opioid dependence, as it is effective in reducing withdrawal signs and has not been shown to produce any negative side effects. By reducing withdrawal symptoms, the patient feels less discomfort during treatment, and we hypothesize this would lead to a decreased risk of relapse.”

Ferrante and Kuhn used rats to model opioid addiction and observed withdrawal symptoms in groups of rats given rapastinel, ketamine, and a saline solution. By day three, rats that had been given rapastinel showed substantially fewer indications of withdrawal symptoms than those given ketamine or a saline solution.

Eventually aiming for human clinical trials, researchers will further investigate the drug’s effect on a molecular level, and whether it is effective in preventing relapse. It’s still unclear how long patients would take the drug.

According to Ferrante:

“Our research suggests that new alternatives to standard treatments for opioid dependence have potential to be safer and more effective,” Ferrante added. “Rapastinel research for opioid dependency is currently only being done in rodents, but if the drug continues to have successful trials, it may enter clinical trials for use in humans.”


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