Naltrexone

What Is Naltrexone?

Naltrexone is an opioid antagonist that is FDA-approved by prescription for long-term management of opioid use disorder (OUD) and alcohol use disorder (AUD). It works by blocking the euphoric effects of opioids on the brain. Naltrexone for OUD and AUD is marketed under the following brand names:

• ReVia (oral tablet)
• Depade (oral tablet)
• Vivitrol (extended-release injectable)

Naltrexone can be combined with other medications for the treatment of other conditions, such as:

• Naltrexone and bupropion: Marketed under the brand name Contrave, it is approved for weight loss in people who are overweight or obese.
• Naltrexone and morphine: Marketed under the brand name Embeda, it is approved for around-the-clock pain management with abuse deterrent features due to the naltrexone.

Although naltrexone is a medication used for AUD and OUD, it is not a cure for addiction. Instead, it is a helpful component of a comprehensive addiction treatment plan that also includes psychotherapy and social support.

Naltrexone Vs. Naloxone: What’s The Difference?

Naltrexone is often confused with naloxone, an opioid overdose reversal medication. Although these medications are both opioid antagonists, they serve very different purposes in people who use opioids.

Naltrexone is a long-term opioid antagonist that helps to manage OUDs and AUDs. Naloxone is a short-acting opioid antagonist that is a life-saving medication administered during an opioid overdose to elicit immediate opioid withdrawal effects. This emergency treatment lasts 30-90 minutes and is often sold under the brand name Narcan. Naloxone does not play a role in the treatment of alcohol use disorder.

How Does Naltrexone Work?

Naltrexone works by binding to the opioid mu receptors in the brain and preventing other opioids, such as heroin, from binding to these receptors (in the case that a person is still using opioids). When naltrexone sits on the mu receptors, it also blocks natural opioids, known as endorphins, from binding. One of the reasons why people continue to use opioids, despite wanting to quit, is the strong cravings and urges from the dopamine rush associated with opioid use. Naltrexone, over time, modulates this opioid-fueled dopamine surge, which leads to reduced euphoria from opioids and alcohol and subsequently decreases urges and cravings for these substances.

Naltrexone also works on part of the brain known as the hypothalamic pituitary axis (HPA), which plays a key role in the body’s stress response, which can be dysregulated in the presence of alcohol. It is still unclear exactly how it works on the HPA to treat alcohol use disorder.

There is no abuse or addiction potential with naltrexone. If a person uses opioids (prescription or illicit) while taking naltrexone, they can experience precipitated opioid withdrawal because naltrexone blocks the effects of opioids. Precipitated withdrawal occurs suddenly and includes telltale opioid withdrawal effects such as muscle pain, diarrhea, cramping, and sweating. Because naltrexone is a long-acting opioid blocker, taking more opioids to help alleviate these already present opioid withdrawal effects will further worsen the withdrawal.

How Is It Administered?

Naltrexone is administered as an oral tablet (ReVia and Depade) or as an extended-release injectable (Vivitrol). The oral tablet form of naltrexone (ReVia, Depade) can be taken at a dose of 50 mg once daily, whereas the injectable extended-release form of the drug (Vivitrol) is administered at a dose of 380 mg intramuscularly once a month.

Naltrexone For Alcohol Use Disorder

Alcohol use disorder, commonly known by the colloquial term alcoholism, is a chronic condition. People with AUD are unable to cut back or stop drinking despite its harmful effects on multiple areas of their daily life. According to the 2023 National Survey on Drug Use and Health, 28.9 million people ages 12 and older had an AUD in the past year.

Alcohol can have drastic negative effects on the liver, heart, gastrointestinal tract, brain, and pancreas, and can lead to poor decision-making and impaired behaviors.

Naltrexone is FDA-approved to help treat alcohol use disorder, as it blocks the euphoric effects associated with alcohol consumption and therefore reduces the alcohol induced dopamine surge. Over time, cravings and urges decrease, and abstinence or reduction in alcohol consumption can be obtained.

Naltrexone does not make you feel sick if you drink alcohol while taking it, and no evidence shows the person must stop drinking for a period of time before initiating it since there is no precipitated withdrawal. However, people should avoid all opioids and even cough syrup with codeine if they are taking naltrexone for alcohol use disorder because it can precipitate unpleasant opioid withdrawal.

Abstinence Vs. Cutting Back: The Sinclair Method

Naltrexone is often used before drinking, known as the Sinclair method, as a way to reduce alcohol use for people who are unable or unwilling to adopt abstinence. Dr. John David Sinclair showed that the longer someone abstained from drinking, the more intense cravings they had, and he called this the “alcohol deprivation effect”. However, when given naltrexone before drinking, the cravings would greatly decrease, resulting in only one alcoholic drink before the person no longer craved alcohol.

Research shows that people with AUD who took naltrexone as needed, one hour before drinking, can have a reduction in cravings and alcohol consumption, therefore reducing the harmful effects of alcohol. This showed that treatments that promoted abstinence were ineffective compared to treatments that helped people cope with drinking by reducing (not fully eliminating) their alcohol intake. Insisting on abstinence can cause a barrier to treatment for people with alcohol use disorder. Many people are not initially interested in abstaining from alcohol but are interested in drastically reducing their consumption.

The Sinclair method is a patient-centered approach that can help people drink less when they take naltrexone one hour before having a drink. The euphoric “buzz” from alcohol is eliminated once naltrexone is in the system, and the desire to drink more is suddenly stopped.

The antagonist effect of naltrexone on the natural opioid receptors (endorphins) is blocked, and this “wall” prevents alcohol induced euphoria, reducing cravings. In other words, one drink is enough and sometimes even more than enough. However, four to six hours after taking naltrexone, a strong drink can cause a relapse because naltrexone is not at its maximum concentration at this point. Therefore, it is important to have healthy coping skills, a strong support system, and effective psychotherapy approaches, as well as medications such as naltrexone to help treat alcohol use disorder.

Naltrexone For Opioid Use Disorder

Opioid use disorder has become an epidemic in the United States and across the globe, affecting more than 2.1 million people in the United States and 16 million people worldwide. More than 120,000 deaths worldwide every year are attributed to opioids. Whether it is illicit opioids, such as heroin, or prescription opioids, such as morphine, oxycodone, and tramadol, opioid misuse can quickly spiral into opioid dependence and further into opioid addiction.

Opioid use disorder can affect every aspect of your life, from your home life and personal relationships, mental and physical health, to your professional endeavors and finances. Opioid use disorder can result in unintentional overdose, which can be deadly.

Naltrexone is one of many medications that can be given to people with an OUD and has been shown to be effective when combined with other comprehensive treatments such as cognitive behavioral therapy, contingency management, group therapy, and a strong, healthy support structure.

If a person and their medical team agree to use naltrexone as part of a treatment plan for OUD, the person must be opioid free for at least 7-10 days before starting naltrexone. This is because naltrexone will bind to the opioid receptors and block all opioids that are already in the body, causing a precipitated opioid withdrawal or rapid withdrawal. Even if a person is on methadone for opioid use disorder, they will have to taper off methadone and be opioid free before starting naltrexone, since methadone is an opioid. Because of this, many treatment providers will test for opioids using a urine drug screen.

Side Effects Of Naltrexone

Like with any medication, naltrexone is known to have side effects. Common side effects associated with naltrexone include the following:

• Nausea
• Stomach cramps
• Diarrhea
• Muscle cramps and stiffness
• Headaches
• Sleep disturbances (insomnia and hypersomnia)

Additionally, precautions to note before using naltrexone include:

• Precipitated withdrawal: If a person using naltrexone has opioids in their system, they will experience immediate opioid withdrawal. 
• Reduced tolerance to opioids: People taking naltrexone for OUD may have a reduced tolerance to opioids since they are no longer taking them. If they do relapse, after a period of abstinence, they may be unaware of how sensitive a lower dose can affect them. The dosage of opioids they were once using may have life-threatening consequences, such as respiratory arrest, because of their decreased tolerance. This can cause a deadly overdose.

If anyone is showing signs of opioid overdose, it is important to administer naloxone immediately and call 911.

Naltrexone Interactions

Naltrexone is known to interact with certain medications, primarily those that contain opioids, such as:

• Prescription opioids
• Illicit opioids
• Cough medications containing opioids
• Antidiarrheal medications containing opioids

Is Naltrexone Right For Me?

If you are struggling with addiction, specifically opioid use disorder or alcohol use disorder, naltrexone can help you reduce cravings and cut back on misuse.

It is important to talk to your healthcare provider about your opioid or alcohol use and also discuss a comprehensive treatment plan that not only includes naltrexone but also psychotherapy approaches, as well as support groups. Regardless of the decision between you and the healthcare provider, there are other medication treatment options to help treat both opioid and alcohol use disorder.

Naltrexone is not for everyone, and it is important to speak with your healthcare professional about naltrexone before starting this medication. Pregnant or breastfeeding women and people who are currently under the influence of opioids should avoid naltrexone. People who have severe liver disease and moderate to severe kidney disease should also avoid naltrexone.

Where Is Naltrexone Available?

Naltrexone is available by prescription from any prescribing healthcare provider. It is not a controlled substance and does not require special training for prescription.

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If you’re struggling with an opioid or alcohol addiction, naltrexone treatment could be beneficial as part of your treatment plan. To learn more about your treatment options, including inpatient facilities that utilize naltrexone, contact a treatment provider today.