Naltrexone is a medication classed as an opioid receptor antagonist. It is approved by the Food and Drug Administration (FDA) for use in the treatment of alcohol use disorder (AUD) and opioid use disorder (OUD). Naltrexone reduces the rewarding effects of alcohol and opioids and decreases the likelihood of relapse. Many people also experience reduced cravings, although this effect varies from person to person. [1]
Naltrexone is available as an oral tablet, which is typically administered once daily, and also as an extended-release injectable formulation, administered once a month. [1] Some side effects and risks can occur, and it is important to consult with a licensed physician or specialist before and during treatment.
- Naltrexone can reduce alcohol cravings and alcohol use.
- Naltrexone can be administered as a daily oral tablet or a monthly injection.
- Naltrexone can be helpful for people with moderate to severe alcohol use disorder who want to reduce alcohol consumption or maintain abstinence.
How naltrexone works for Alcohol Use Disorder (AUD)
Naltrexone can be safely and effectively used in the treatment of AUD.
Naltrexone primarily affects the mu-opioid receptors in the brain, but it has also been shown to work, to a lesser extent, on other opioid receptors. These receptors release endorphins known as opioid peptide ligands when alcohol is consumed. This acts as a reward or pleasure signal, reinforcing alcohol consumption. Naltrexone blocks these receptors, preventing endorphins and the reward response. [2][3]
This helps people reduce alcohol consumption, as the brain stops associating alcohol consumption with pleasure, so cravings and urges become reduced. [3]
Additionally, alcohol can activate k-opioid receptors after prolonged use, which leads to feelings of depression. This causes cravings for alcohol in order to lift the mood and heighten emotional state. Naltrexone prevents alcohol consumption, leading to k-opioid receptor binding, thereby preventing the development of depressive symptoms and the associated relief from alcohol consumption. [2]
Who is a good candidate for naltrexone?
Naltrexone for AUD can be suitable for people with moderate to severe AUD who are motivated to engage with AUD treatment and have struggled to stop drinking without professional support. [3]
Since naltrexone needs to be taken regularly in order to have therapeutic effects for AUD, low willingness can lead to non-compliance, which significantly impacts the outcomes of naltrexone treatment. Regular reviews and monitoring, or the use of monthly injections, can help with this. [1]
The prescribing physician will conduct a medical assessment prior to commencing treatment to ensure suitability. It is important to disclose any history of physical or mental health issues, recent or current medications, and any prescribed or illicit opioid use.
Who should not take naltrexone?
Naltrexone should NOT be used by: [1][4]
- Pregnant or breastfeeding people, as it can affect the child. People who get pregnant during naltrexone treatment should discuss this with their physician to weigh the risks against the benefits.
- People under 18, as safety and effectiveness have not been established.
- People with liver or kidney issues may need a reduced dose or might not be safe to use naltrexone.
- People who currently use opioids, whether illicitly or prescribed, or those with a current opioid dependence, as naltrexone can cause the onset of severe opioid withdrawal.
Effectiveness with AUD
Various studies have investigated the effectiveness of naltrexone in the treatment of AUD. Generally, naltrexone treatment results in better outcomes than placebo, including preventing relapse, improving length of abstinence, reducing the number of days drinking, and reducing the number of drinks per occasion. [3][5]
Extended-release naltrexone is found to cause a significantly better outcome than oral naltrexone. This is likely due to a reduced risk of non-compliance with monthly injections. Daily oral naltrexone is shown to have high rates of non-compliance or discontinuation. [5][6]
Studies also highlight improved outcomes in those who have an initial period of abstinence before commencing treatment of at least four days, and those with a longer duration of treatment. Engaging in behavioral interventions alongside naltrexone treatment can also improve outcomes. [3][7]
What to expect during treatment
Before starting treatment, the physician will likely conduct liver and urine tests to determine whether there could be issues with liver function while taking naltrexone and whether other substances are present. They may recommend that the individual attempt to abstain from alcohol for several days before commencing treatment. [3]
Starting the medication
Often, treatment will start with a low dose of oral naltrexone, which can be increased gradually and, if appropriate, changed to monthly injections. Commencing on a low dose can help to ascertain individual responses to the medication and reduce the risk of serious side effects. It is common to experience nausea, headache, and fatigue at the start of a new treatment. [2][4]
How long treatment lasts
Naltrexone treatment should last at least a few months. The duration of the treatment can depend on the individual. If they experience strong cravings, instances of heavy drinking, or issues impacting compliance, treatment should be continued for longer. It is safe to use naltrexone long-term. [3]
Follow-up care and monitoring
People using naltrexone should have regular reviews with the prescribing doctor to monitor the effectiveness of the treatment and any adverse effects. It can also be beneficial to engage with an alcohol use disorder specialist during treatment, along with counselors or therapists, to receive a comprehensive and integrated treatment plan to manage AUD and prevent relapse. [1][8]
Side effects and safety
Naltrexone can cause some mild side effects at the start of a new treatment, including nausea, vomiting, headaches, and fatigue. Typically, these will last a maximum of a couple of weeks. Vivitrol can also cause some swelling or reaction at the injection site. [1][4]
In some cases, naltrexone can lead to mood changes and should be monitored for signs of depressed mood and suicidal ideation. [4]
Naltrexone can cause elevations in liver enzymes, although clinically significant liver injury is uncommon at recommended doses. Liver function should be assessed before treatment and monitored when clinically indicated. [2]
Can you drink while taking naltrexone?
Unlike disulfiram, naltrexone does not cause nausea and vomiting if alcohol is consumed during treatment. Naltrexone prevents alcohol from causing a pleasurable effect and does not cause a dangerous reaction with alcohol. [7]
However, drinking while using naltrexone treatment does not reduce the effects of alcohol or the potential for psychological or physical harm, and can have negative impacts on recovery.
Naltrexone vs. other AUD medications
FDA-approved medications for AUD include: [8]
- Naltrexone: Naltrexone works by limiting the pleasurable effects in the brain that reinforce alcohol use, which can reduce cravings and drinking. Studies show improved outcomes of injectable naltrexone compared to oral naltrexone. [1][5]
- Acamprosate: Acamprosate is a safe and effective treatment for AUD. It can be safely started during withdrawal, although it is often recommended to commence after 5-7 days of abstinence. It can help reduce cravings and alcohol use. Compliance is a commonly reported issue, as acamprosate requires three doses per day. [7][8]
- Disulfiram: Disulfiram causes a reaction in the body if alcohol is consumed, which causes unpleasant effects such as nausea, vomiting, and headaches. This requires close monitoring due to physical and psychological effects and is not a first-line treatment because of this. However, it can be a very helpful deterrent. [7][8]
How naltrexone fits into a full treatment plan
Naltrexone alone may not be enough to fully support AUD recovery. Often, it is helpful to engage in behavioral therapy, as this can enable behavioral changes around drinking habits and help to develop positive coping strategies to manage underlying emotional distress. [3][8]
Utilizing specialist help can support abstinence and AUD recovery, including developing relapse prevention plans and setting goals to maintain motivation.
Conclusion
Naltrexone can be a helpful intervention for people with AUD and is often a safe and effective treatment. In some cases, risks and safety issues can occur, and it should always be used with professional advice and monitoring.
People who are concerned about their alcohol consumption can seek professional advice about available treatments and how to access specialist services.
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