Naltrexone (trade names ReVia, Depade, and Vivitrol) is an opioid antagonist medication. Naltrexone is often administered to individuals in recovery to suppress cravings for opioid drugs or alcohol. Opioid replacement medications, such as buprenorphine (the active ingredient in Suboxone) and methadone, activate opioid receptors, suppress cravings, and decrease withdrawal symptoms because these substances are very similar to other opioid drugs. Naltrexone actually blocks the opioid receptors in the brain by binding to them, knocking off any opioid drugs on these receptors, and this helps to reduce cravings for these drugs; however, it may also result in an individual experiencing rapid withdrawal.
Naltrexone comes in pill form (ReVia and Depade) and as an injectable extended-release form (Vivitrol). If an individual has taken naltrexone and then uses an opioid drug or alcohol, the individual will not experience the psychoactive effects of the drug; however, there are complications associated with this situation (see below).
It is important to understand that naltrexone does not treat the symptoms of withdrawal from alcohol. Because alcohol withdrawal can be potentially fatal, individuals should only attempt to discontinue moderate to heavy alcohol use under the supervision of a physician.
Abuse Potential of Naltrexone
Naltrexone has no potential for abuse. Its use cannot result in the development of physical dependence. It is not considered to be a potential drug of abuse; however, it does require a prescription from a physician in order to be legally obtained.
Naltrexone Use for Opioid Use Disorders
Naltrexone was approved for the treatment of opioid use disorders in 1984. While the drug does reduce cravings to some extent and may even reduce the effects of opioids, issues with compliance often complicate its effectiveness. Because individuals can stop taking the pill whenever they want to use an opioid drug, a large review of research reported by the Cochrane Foundation in 2011 concluded that the oral form was no more effective than placebo in reducing relapse to opiates.
Individuals who are motivated to quit using opiate drugs may fare better, and individuals who are placed in formal substance use disorder therapy while taking naltrexone may also have an advantage. Simply being prescribed the pill form of the drug does not appear to be effective due to issues with compliance. Research has found better success for the injectable form of naltrexone in regard to treatment compliance. This is because the injectable form is an extended-release form that does not require daily dosing.
Naltrexone Use for Alcohol Use Disorders
Naltrexone has had moderate success in research studies investigating its effectiveness in treating alcohol use disorders. The overall findings indicate that in research studies, it is associated with a decrease in heavy alcohol use, the total amount of alcohol consumed, and the number of times an individual drinks alcohol. Nonetheless, like its use in the treatment of opiate use disorders, research indicates that compliance is always an issue with medications designed to reduce cravings or the desire to use any substance. Again, use of the injectable form of naltrexone helps to overcome issues with compliance to some extent; however, individuals can simply stop showing up for their injections.
It is generally suggested that using naltrexone for the treatment of an opiate use disorder or alcohol use disorder should continue for at least three months and be accompanied by active participation in therapy and a formal substance use disorder treatment program.
There are some research studies that suggest that naltrexone may offer treatment utility for certain types of compulsive behaviors, such as kleptomania. Most of these findings are tentative, and the drug is not approved for these uses at this time.
Potential Side Effects and Limitations of Naltrexone
According to the Food and Drug Administration (FDA):
- The most frequent side effects of naltrexone are gastrointestinal issues that include diarrhea, nausea, and abdominal cramps.
- Headaches and muscle cramps may occur in some individuals.
- At high doses, naltrexone may cause liver damage.
- Naltrexone should not be used by pregnant women.
- It is generally recommended that individuals who use naltrexone should be abstinent from other opioid medications/drugs for 7-10 days. Because naltrexone occupies opioid receptors, it replaces opioids that are already attached to those receptors. As a result, if an individual has not completed the withdrawal process, they may experience an acute withdrawal reaction. Often, before a physician administers the full dose, they give the patient a small dose to determine if a withdrawal reaction will occur.
- The FDA also suggests that individuals who are taking naltrexone not use other opiate drugs/medications. Because the medication blocks the opiate receptors in the brain, users run the risk of overdosing on opioid drugs if they begin using them while on naltrexone. Because an individual taking naltrexone will not experience the psychoactive effects of other opiate drugs immediately, they may take extremely high doses of the drugs. This can lead to a dangerous situation where the individual overdoses.
- In addition, some studies suggest that naltrexone reduces tolerance for opiates. Thus, individuals who used naltrexone in the past may have significantly decreased tolerance to other opiates and may run the risk of overdose if they relapse even after they have not used naltrexone for some time.
Naltrexone is an opioid antagonist, meaning that it attaches to and blocks opioid receptors in the brain. This results in a potentially useful situation for individuals in recovery that may lead to decreased cravings for specific types of drugs, particularly alcohol or other opiate drugs. Naltrexone is not a cure for addiction to these drugs or a substitute for therapy; it is an adjunctive medication that can help in the treatment of substance use disorders.
Naltrexone works best in combination with formal substance use disorder treatment and not as a standalone intervention. It works best for individuals who are motivated to be successful in their recovery. Individuals who are not motivated to stop using these drugs will often find ways to stop taking the medication or simply continue using their drug of choice. There are some risks associated with naltrexone, and individuals should be informed of these risks before they are prescribed the drug.