Naltrexone is used to treat both opioid and alcohol addiction.
First, a quick clarification of the difference between naltrexone and naloxone
“You can revive an opioid overdose with naltrexone … er, I mean naloxone,” is a fumble I’ve heard more than once, sometimes from the mouths of medical professionals. I think the issue is partly the name—both these medications contain a lot of the same letters—and the fact that they are both used in the treatment of substance use disorders, and even share similar chemical structures. But it’s important to understand that naltrexone and naloxone are, in fact, distinct chemicals with different uses.
Naloxone is primarily used to reverse an opioid overdose, but it is also added in small amounts to some buprenorphine formulations, like Suboxone, in an attempt to deter misuse. It works fast and metabolizes quickly—so the effects will wear off within an hour (which is why people who have overdosed should remain under supervision after having naloxone administered). Naltrexone, on the other hand, has a distinctly different function. Though not an opioid, like buprenorphine, it can completely block the euphoric and pain-relieving effects of opioids, helping to deter opioid misuse by erasing the ability of a user to get high. It begins working slower and is longer lasting, so it won’t help in an overdose, but can help to manage an opioid use disorder. And, unlike naloxone, naltrexone has been approved by the FDA to treat both opioid and alcohol use disorders.
How Is Naltrexone Administered?
Naltrexone can be administered in either the form of a daily pill, an extended-release injection that lasts about a month, or an implant that can last two to six months. There are risks and benefits to each administration. In the daily pill form, a user must take it once every morning in order for it to be effective each day. That leaves more potential for errors or “non-compliance,” giving users the choice to abstain from the pill one day in order to feel the full effects of an opioid. If a user struggles to maintain self-control without assistance, this might present a problem. However, it will allow for a user to access the pain-relieving effects of an opioid within about 24 hours if she becomes injured. It also gives users more freedom. If someone’s goal is to moderate his usage rather than stop completely—for example, if he wanted to still use opioids occasionally but not enough to develop a physical dependence—he could potentially use it for that more harm-reduction-oriented purpose.
The injection form lasts about a month and can’t be reversed. A user will not feel the effects of opioids for one month and should see a decrease in opioid and alcohol cravings during that time. The biggest drawback to this is that if she becomes seriously injured during this time period, she will not be able to use opioids to numb the pain. There is some speculation that naltrexone might also interfere with the psychological benefits of exercise as well as pain relief after an injury.
The implant comes with the same problem, though it can be removed. If removed, the effects of opioids can be felt within a few hours or days, depending on how long it takes for the remaining drug to clear the body. But patients might find their doctors unwilling to remove the implants without a good reason. Some former naltrexone implant patients have stated that their desire to use remained so great that they tried to cut the implant out themselves, which is a pretty gruesome outcome.
“Naltrexone, by blocking the opioid receptor, prevents these endogenous opioids from having an effect and that limits the rewarding and positively reinforcing aspects of drinking”
How Is Naltrexone Used For Alcohol Use Disorder?
Naltrexone works by filling and blocking opioid receptors—which is why patients cannot feel any effects from opioids. It won’t block the effects of alcohol or make someone sick when they drink, but it has been shown to help reduce alcohol cravings. Several studies found that patients were able to abstain from alcohol longer, or reduce daily drinking to less problematic levels (around two drinks per day versus five or more). “The idea is that drinking alcohol causes pleasure by triggering the release of endogenous opioids in the brain”, says Dr. Sarah E. Wakeman, an addiction medicine physician who practices at Massachusetts General and teaches at Harvard University. She adds, “Naltrexone, by blocking the opioid receptor, prevents these endogenous opioids from having an effect and that limits the rewarding and positively reinforcing aspects of drinking.” It’s not a cure for alcohol addiction, but it can be an aid for people hoping to cut down or totally stop drinking.
Methadone and buprenorphine are considered to be the gold standards for opioid use disorder, but naltrexone is the only medication that is shown to help with both opioid and alcohol addiction. If you’re struggling with a polysubstance addiction that includes both opioids and alcohol, it’s worth looking into naltrexone to see if it can help.