Naltrexone Implant for Alcohol Use Disorder

When naltrexone is prescribed in the form of an implant, it can make it easier for people who have a hard time taking medications every day (like with naltrexone tablets) or those who would prefer not to get a monthly injection (like with Vivitrol, the branded form of injectable naltrexone).

Naltrexone implants are a form of medication-assisted treatment (MAT) for alcohol addiction that require the surgical insertion of small pellets that contain naltrexone, usually in the abdomen.[2] The implant then provides a steady stream of naltrexone into the bloodstream for up to six months, depending on the formulation. 

This medication is an opioid antagonist, which means that it binds to opioids receptors in the brain and blocks the euphoric effects of alcohol if the person relapses and drinks.[3] It also reduces cravings for alcohol, making it easier to stay focused on the work required in recovery. 

How Does the Naltrexone Implant Work?

Naltrexone implants release a steady stream of the medication into the bloodstream over a period of months. Here’s how they work:[2]

Implantation

The implant itself is made up of small pellets or capsules that contain naltrexone. It is inserted below the skin in the abdominal region during a minor outpatient surgical procedure.[2] In most cases, people need only a local anesthesia, and the whole thing is over within minutes. 

Slow-Release Formula

The release rate of the medication inside the body is designed to be slow and steady. The goal is to get to and maintain therapeutic levels of naltrexone in the system at all times.

Opioid Receptor Blocking 

Because it is an opioid antagonist, naltrexone binds to the opioid receptors in the brain—the receptors that play a role in the cravings that define alcohol addiction.[4] By binding to those receptors, naltrexone stops other substances from binding there. This means that if someone drinks or uses opioids, the naltrexone will stop the person from feeling drunk or high. 

Additionally, it reduces the cravings that a person experiences on a day-to-day basis, which allows them to focus on their recovery. 

Lengthy Efficacy 

The fact that naltrexone implants last for months is a big selling point for people who have a hard time managing or remembering their medication. This makes it easier to stick to their recovery long enough to see the benefits of interventions that can take time to have an impact like behavioral therapy and holistic treatments. 

How Are Naltrexone Implants Administered?

Naltrexone implants are only available with a doctor’s prescription. A step-by-step process must be followed both before and after the surgery, not only to ensure that the medication is a good fit for the patient but that they have all the information and support they need to get the most out of the implant. Here is what to expect:

Patient Evaluation

A doctor must have a comprehensive understanding of the patient’s history with substance use and abuse, know what other treatments they’ve tried for addiction, what other medical issues they may be facing, if there are any mental health problems in the equation, and if there are other medications that they take regularly. All of this information can help the doctor determine if an implant is the best choice for their goals. 

Patient Education

There is quite a bit of information to know and understand about naltrexone implants, starting with how they work in the body. Someone who is at risk of relapse needs to know what effects occur if they drink as well as understand the process for getting the implant and managing their treatment, both in and out of the doctor’s office. 

Informed Consent

Once the patient understands the potential risks, side effects, and benefits as well as the details of how treatment with a naltrexone implant will work, the patient needs to have time to ask questions and then make an informed consent before moving forward.[5]

Surgical Procedure

The inpatient procedure for inserting the naltrexone implant is relatively simple. It takes just a few minutes to insert beneath the skin, usually in the abdominal area. The patient needs only local anesthesia and can go home as soon as a brief monitoring period is over.

Patients will be given information on how to care for the implant site as it heals, what activities to avoid, and potential complications to look for. The device itself contains naltrexone pellets or capsules, the number of which will vary depending on how long the implant needs to last and the patient’s personal needs. 

Continual Monitoring

After the procedure, it’s important for the patient to follow up with the doctor regularly to make sure that the treatment is effective and to manage any issues that arise during the healing process and beyond. These may include physical exams, lab tests, and assessments regarding substance use. 

Side Effects of the Naltrexone Implant

Naltrexone implants, like any medication, have the potential to cause side effects. While many people tolerate naltrexone implants without issue, some may experience an adverse reaction. Some possible side effects include the following.[6]

Localized Reactions

After the implant surgery, some people may see some redness at the insertion site or experience pain, swelling, redness, or irritation. 

In most cases, these reactions are mild and resolve on their own with time, but in some cases, an infection can develop. If this is the case, the person may experience warmth, drainage, redness, and swelling in the area. This requires prompt medical attention.

Allergic Reactions

It’s rare, but some people are allergic to naltrexone. If this is the case, they may see a rash or hives, experience itching or difficulty breathing, and/ or have swelling in the face, lips, tongue, or throat. If an allergic reaction occurs, immediate medical care is necessary.

Mood Swings

In some cases, naltrexone can cause changes in mood or emotions. Some people may see a shift toward depression, anxiety, irritability, or mood swings. When they occur, these effects are usually mild and resolve on their own, but if it becomes a chronic issue, it’s important to seek medical advice.

Gastrointestinal Issues

Naltrexone can cause gastrointestinal side effects in some people that can include nausea, vomiting, diarrhea, or constipation. These symptoms are usually mild and pass on their own, but they may require medical attention if they become severe or persistent.

Headache

Some individuals may experience headaches as a side effect of naltrexone treatment or an exacerbation of migraines if those are a pre-existing condition. In most cases, regular headaches should pass with use of over-the-counter medication. 

Sleep Disturbances

Naltrexone can sometimes affect sleep patterns and quality of sleep due to insomnia or other sleep disturbances. People who experience sleep-related issues can address the issue with their doctor and get lifestyle tips, alternative options for improving sleep quality, and potentially alter the naltrexone dose if needed.

Liver Toxicity

Although rare, naltrexone has been associated with liver toxicity in a few cases. People who have a pre-existing liver condition or abnormal liver function may be at higher risk. For all patients but especially those living with liver dysfunction, the prescribing physician should monitor liver function periodically throughout naltrexone treatment.

Who Is a Good Candidate for the Naltrexone Implant?

Determining who is a good candidate for a naltrexone implant involves taking into account a number of factors that include the patient’s medical and substance abuse history, treatment goals, and current health status. 

Depending on where the diagnosis is actually taking place (the state, municipality, and medical center), the criteria may vary slightly, but in general, there are a few musts that should be in place before a person will be prescribed a naltrexone implant. Here are the criteria:

Addiction Diagnosis

First and foremost, the person must be living with an addiction to either alcohol or opioids. The primary function of naltrexone is to help people avoid relapse. If they feel that they are able to drink normally or take prescription painkillers as prescribed without abusing the medications, they don’t need naltrexone in any form. 

If a person has a history of substance abuse but no formal diagnosis, the doctor will likely use the criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) to verify their status and make it official in their medical record.[7]

Failure of Other Treatments

Getting an implant of any kind is a relatively extreme step for substance abuse treatment because there are other noninvasive methods that allow for the medication to be processed out of the body much more quickly. This is ostensibly part of the reason why the FDA has yet to approve it for use in the United States.

Naltrexone implants are generally only recommended for people who have tried other medications designed to treat alcohol addiction and failed.[8] That means that if they had tried other medications, including oral or injection versions of naltrexone, and been unsuccessful in treatment, the doctor may determine that they are a good candidate for a naltrexone implant. 

Mental & Physical Stability

A person who will benefit from a naltrexone implant will be stable in terms of their medical status and mental health. Acute medical conditions and extreme mental health issues, especially if untreated or treated with medications that may counteract the naltrexone, may make the implant less successful and potentially harmful. 

Specifically, it is important for the person to be free of medical conditions that impact their liver and kidney function, as the medication could worsen those issues. 

Treatment Readiness

Not everyone who recognizes the need to put drug and alcohol abuse in the past are ready to commit to long-term abstinence. A naltrexone implant requires the patient to be free of drugs and alcohol for at least the period in which they have the implant in place. To help them stay the course, it is generally recommended that they take part in other forms of treatment, including behavioral therapy, group counseling, and other interventions.[9]

What Are the Benefits of the Naltrexone Implant Compared to Other Forms?

Despite the risks, some people in other countries (where the medication is allowed) have been able to find stability in recovery through the use of naltrexone implants. Some advantages of the medication include the following: 

Ongoing & Long-Lasting Medication Delivery

Perhaps the biggest benefit of a naltrexone implant over other versions of naltrexone is its ability to provide sustained and ongoing medication delivery over an extended period of time, usually anywhere from two to six months, depending on the formulation used. This means that the patient does not need to manage or remember daily medication and refills, which cuts down on the risk of missing doses.

Increased Consistency in Treatment

When someone is able to consistently take their medication, it’s easier for the medication to do its job. This makes it easier for the patient to stick to their treatment program and build momentum in recovery.

Lower Risk of Diversion

Unlike oral medications that are designed to be taken daily, there is no risk that the patient will sell their medication on the black market or otherwise misuse the drug. This is safer for everyone. 

Increased Bioavailability of Naltrexone

Oral naltrexone undergoes first-pass metabolism in the liver, which means that it is processed through the liver before it is able to bind to opioid receptors.[10] Naltrexone implants are not processed in this same way, allowing the medication to be delivered directly into the bloodstream. This increases its bioavailability, which translates to a more consistent level of medication in the system over time.

Lesser Stigma for Medication Use

Many people in recovery worry about stigma or judgment from others related to their addiction. The implant option of naltrexone is discrete and offers a more private means of healthcare, allowing people to deal with their addiction issues confidentially. 

Potentially Lower Risk of Side Effects

While naltrexone implants can cause side effects like other forms of the drug, its steady and controlled release of the medication into the body may help to cut down on the risk of certain side effects that come with oral or injectable formulations, such as gastrointestinal symptoms or changes in drug levels.

How Effective Are Naltrexone Implants? 

Although naltrexone implants are not yet approved by the FDA for use in the U.S., there are a number of studies that show promising results for people who are in recovery from both AUD and opioid use disorder (OUD).[11]

A study in Australia found that naltrexone implants were found to be exceptionally effective for people in recovery from OUD. Compared to those who took naltrexone orally, patients who had the naltrexone implant were more likely to stick with their treatment for longer, return to treatment more quickly if they did relapse, and have better outcomes overall in terms of stability in recovery.[12] 

Another study found that naltrexone implants were significantly more effective than placebo implants in helping people in treatment to remain committed to their recovery.[13] However, this same study found that relapse was more likely among those who had a naltrexone implant compared to those who took the medication orally. 

Work With Your Treatment Team

The right choice in MAT for your alcohol abuse issues will be individualized to your needs. There isn’t a one-size-fits-all solution for everyone. Talk to your treatment team about your current situation and your long-term goals in recovery. They will help you find the right combination of medication and therapy for you.