Allergan's depression drug looks promising for opioid withdrawal

Allergan said last month that rapastinel – the centerpiece of its $ 560 million acquisition of Naurex – had failed in three pivotal trials in the treatment of major depressive disorder. But not everything is lost. Scientists from Duke and Villanova Universities may have found a use of the drug in the treatment of opioid withdrawal.

People who become opioid-dependent may experience excruciating withdrawal symptoms such as anxiety, vomiting, diarrhea, and insomnia. These symptoms often prevent them from asking for help or relapse in patients seeking treatment for addiction.

Rapastinel could help manage these symptoms, according to a new study by Julia Ferrante of Villanova University and Cynthia Kuhn of Duke University. The experimental drug significantly reversed the signs of acute weaning in the rat in three days, the researchers said in a statement. The study was presented at the annual meeting of the American Society of Pharmacology and Experimental Therapy in Orlando.

There are drugs approved by the FDA for treating opioid-related disorders. Buprenorphine and methadone are commonly used to help eliminate cravings for opioids. But they are also opioids that can be abused, they can cause side effects and patients sometimes have to use them in the long term to avoid relapses.

Two other drugs, naloxone and naltrexone, are not opioids. However, patients must detoxify before they can use naltrexone, and naloxone is more appropriate in emergency situations to reverse opioid overdoses.

Rapastinel, in comparison, binds to the same NMDA receptor as that used by ketamine, the "party-drug", but at a different site. In their study, Ferrante and Kuhn presented rats with models of opioid dependence in the form of rapastinel, ketamine, or saline. On the third day, rats receiving rapastin had significantly less weaning than other animals, the researchers said.

RELATED: An opioid vaccine could help overcome addiction

Overdose of opioids has become a public health crisis in the United States. About 130 people die each day from an opioid-related drug overdose, according to the US Department of Health and Human Services. As health regulators pursue tactics to reduce the use of opioids, scientists are stepping up their research efforts and looking for new ways to combat addiction.

In May, the FDA designated the US's Lucemyra in the WorldMeds as the first drug specifically approved for opioid withdrawal, which has been used for more than two decades in the United States.

Scientists at the Walter Reed Army Research Institute have already discovered that a heroin vaccine could block the euphoric effects of opioids on the brain by preventing heroin to cross the blood-brain barrier.

Although the use of rapastinel in depression has proven to be a stalemate, clinical trials have shown that it is well tolerated in humans. Before opioid withdrawal studies lead to rapastinel, additional studies are needed to study its molecular effects and determine whether it can reduce the risk of relapse, according to the researchers.