Naltrexone: How It Works for Alcohol and Opioid Use Disorders

From Behavioral Health Wiki, the evidence-based reference

What Is Naltrexone

Naltrexone is a medication that helps people with alcohol use disorder and opioid use disorder. The FDA approved it in 1984 for opioid addiction. Later, in 1994, they approved it for alcohol addiction.^[1]

This drug belongs to a group called opioid antagonists. These drugs block opioid receptors in the brain. By blocking these receptors, naltrexone reduces cravings. It also makes drinking alcohol or using opioids less rewarding.

Doctors prescribe naltrexone as part of a full treatment plan. This plan includes counseling and support groups. The drug works best when used with other treatments. It is not a cure on its own.

Naltrexone comes in two forms. One is a daily pill. The other is a monthly injection. Both forms have the same active ingredient. They work in the same way but have different dosing schedules.

How It Works in the Brain

Naltrexone blocks opioid receptors in the brain. These receptors are like locks. Opioids and alcohol are like keys that fit into these locks. When the keys turn the locks, people feel pleasure or euphoria.

Naltrexone acts like putting glue in the locks. It sits on the opioid receptors and blocks them. This prevents opioids and alcohol from creating their usual effects. People do not feel the same high or reward from using these substances.^[2]

The brain has three main types of opioid receptors. They are called mu, delta, and kappa receptors. Naltrexone blocks all three types. It has the strongest effect on mu receptors. These are the main receptors involved in addiction.

When people drink alcohol, their brain releases natural opioids called endorphins. These endorphins make drinking feel good. Naltrexone blocks the receptors where endorphins work. This makes alcohol less enjoyable and reduces the urge to drink more.

The blocking effect is competitive. This means naltrexone and opioids compete for the same receptors. If someone takes a large amount of opioids while on naltrexone, the opioids might overcome the block. This is why the medication works best with counseling and support.

FDA-Approved Uses

The FDA has approved naltrexone for two main conditions. The first is opioid use disorder in adults. The second is alcohol use disorder in adults. The drug is not approved for children or teens under 18 years old.^[3]

For opioid use disorder, naltrexone helps prevent relapse. People must be completely off opioids before starting treatment. They need to wait 7 to 10 days after their last opioid use. This waiting period prevents withdrawal symptoms that could be dangerous.

For alcohol use disorder, naltrexone reduces heavy drinking days. It also helps people drink less overall. The goal is not always complete sobriety. Some people use it to reduce harmful drinking patterns while working toward abstinence.

Doctors sometimes use naltrexone off-label for other conditions. These include gambling addiction and other behavioral addictions. However, the evidence for these uses is limited. The FDA has not approved naltrexone for behavioral addictions.

Dosing and Forms

Naltrexone comes in two main forms. The oral form is a daily pill called ReVia or generic naltrexone. The typical dose is 50 mg once daily. Some people start with 25 mg to reduce side effects.

The injection form is called Vivitrol. It is given once monthly by a healthcare provider. Each injection contains 380 mg of naltrexone. The injection goes into the muscle of the buttock. It slowly releases medication over 30 days.^[4]

The daily pill requires good adherence. People must remember to take it every day. Missing doses can reduce its effectiveness. The monthly injection solves this problem. It ensures steady medication levels without daily pill-taking.

Some doctors prescribe different doses based on individual needs. Lower doses may work for some people. Higher doses are sometimes used but require careful monitoring. The standard doses work best for most people.

People can take naltrexone with or without food. Taking it with food may reduce stomach upset. The timing of the daily dose does not matter much. Most people take it in the morning to avoid sleep problems.

Clinical Evidence

Many studies show that naltrexone works for alcohol use disorder. A large review looked at 50 studies with over 7,000 people. Naltrexone reduced heavy drinking days by about 4% compared to placebo. It also helped people drink less overall.^[5]

The COMBINE study was a major trial with 1,383 people. It tested naltrexone with and without counseling. People taking naltrexone had fewer heavy drinking days. They also had more days without any alcohol. The benefits lasted throughout the 16-week study.

For opioid use disorder, naltrexone prevents relapse after detox. Studies show it works best when people are motivated to stay sober. The monthly injection form has better results than daily pills. This is likely because people cannot skip doses.

A study in Russia followed 250 people with opioid addiction. Those who got naltrexone implants stayed sober longer. They also had fewer overdoses. The implants slowly released medication for several months.

Naltrexone works better in some people than others. People with strong family support do better. Those who are highly motivated also have better results. The medication works best as part of complete treatment programs.

Side Effects and Safety

Common side effects include nausea, headache, and fatigue. These usually happen in the first few weeks. Most side effects get better as the body gets used to the medication. Starting with a lower dose can help reduce early side effects.^[6]

Nausea is the most common side effect. It affects about 10% of people taking naltrexone. Taking the medication with food often helps. Drinking plenty of water can also reduce nausea.

Some people get headaches when starting naltrexone. These are usually mild and go away after a few days. Over-the-counter pain relievers can help. However, people should avoid opioid pain medications while taking naltrexone.

Sleep problems can occur with naltrexone. Some people have trouble falling asleep. Others feel tired during the day. Taking the medication in the morning may help with sleep issues.

Serious side effects are rare but important. High doses can damage the liver. People need liver function tests before starting treatment. Regular blood tests monitor liver health during treatment. Anyone with liver disease should not take naltrexone.

The injection form can cause pain at the injection site. Some people get swelling or redness. These reactions are usually mild and go away in a few days. Ice and over-the-counter pain medication can help.

Starting Treatment

Before starting naltrexone, people must be completely off opioids. This includes prescription pain medications and illegal drugs. The waiting period prevents precipitated withdrawal. This is a severe form of withdrawal that can be dangerous.

Doctors use urine tests to check for opioids. Some also use naloxone challenge tests. These tests help make sure it is safe to start naltrexone. People must be honest about their recent drug use.

For alcohol use disorder, people do not need to be sober before starting. Some doctors prefer patients to have a few days without drinking. Others start naltrexone while people are still drinking. Both approaches can work.

The first dose is often given in the doctor's office. This allows monitoring for side effects. People stay in the office for 30 to 60 minutes after the first dose. This helps catch any serious reactions early.

Education is important before starting naltrexone. People need to know that opioid pain medications will not work while taking it. They should carry a medical alert card. This tells emergency doctors about the naltrexone.

Regular follow-up visits are essential. Doctors check for side effects and medication adherence. They also monitor treatment progress. Blood tests check liver function every few months.

Family Considerations

Families play an important role in naltrexone treatment success. They can help with medication reminders and support. Family members should learn about how naltrexone works. This helps them understand what to expect.

One concern families have is safety during medical emergencies. If someone needs surgery or has severe pain, doctors can still provide pain relief. They may use higher doses of opioids or different types of pain medications. The key is telling all healthcare providers about the naltrexone.

Families should know that naltrexone is not a cure. People can still choose to drink alcohol or use drugs. The medication makes these substances less rewarding. It does not eliminate free will or guarantee sobriety.

Some families worry about side effects. Most side effects are mild and temporary. However, families should watch for signs of liver problems. These include yellow skin or eyes, dark urine, or severe stomach pain. These symptoms need immediate medical attention.

The monthly injection can be helpful for families. They know their loved one is getting consistent medication. This removes daily arguments about taking pills. It also provides peace of mind about treatment adherence.

Families should continue other support activities. This includes family therapy, support groups, and lifestyle changes. Naltrexone works best as part of a complete recovery plan. Many people also benefit from treatment for co-occurring disorders like depression or anxiety.