Hope for Opioid Use Disorders

The opioid crisis in the United States has only worsened during the COVID pandemic, with deaths from opioid overdoses surging from 2019 to 2020, an increase driven largely by fentanyl and other synthetic opioids.

Columbia researchers are exploring two innovative treatments—a naltrexone implant and a vaccine—that could help more people with opioid use disorder and save lives.

The naltrexone implant is being studied by Adam Bisaga, MD, professor of psychiatry, and Christine Rohde, MD, professor of surgery, in collaboration with the implant’s Australian inventor, George O’Neil, MD.

At Columbia, Drs. Bisaga and Rohde are testing the effectiveness of the implant, which is inserted under the skin of the abdomen and gradually dissolves, releasing naltrexone over six months. Naltrexone protects against relapse by binding to opioid molecules, reducing cravings, and blocking the euphoric effects of opioids.

Although opioid users can be treated with monthly injections of naltrexone, many patients stop treatment after two or three months, which is not long enough for most people to achieve long-term remission. By providing naltrexone over six months, the implant may offer longer-term benefits and reduce the number of relapses and overdoses.

In the trial, Drs. Bisaga and Rohde are measuring the levels of naltrexone released by the implant. “It is very important that the medication is consistently released throughout the treatment period, avoiding too high blood levels, which can produce adverse effects, as well as too low,” says Dr. Bisaga. 

Another potential long-lasting treatment is being evaluated in the nation’s first trial of an experimental vaccine designed to treat opioid use disorder. Sandra Comer, PhD, professor of neurobiology in the Department of Psychiatry, is the principal investigator of the trial. 

The experimental vaccine—developed by Marco Pravetoni, PhD, professor of pharmacology and medicine at the University of Minnesota—is designed to stimulate the immune system into producing antibodies that bind to oxycodone, a commonly abused prescription opioid. When oxycodone is bound to an antibody, the drug cannot enter the brain. 

By reducing the amount of oxycodone that reaches the brain, the vaccine may reduce the feeling of euphoria that users crave. The trial is primarily designed to determine if the vaccine is well-tolerated and safe. Dr. Comer and colleagues also will determine if the vaccine produces sufficient antibodies and can prevent euphoria when the volunteers are given oxycodone. 

Because the chemical structure of opioids varies, different vaccines would be needed for each opioid. The teams at Columbia and the University of Minnesota are working to develop similar vaccines against heroin and fentanyl.