Naltrexone Implant: Opioid Addiction

In 2016, the United States Food and Drug Administration approved a new treatment for opioid addiction: buprenorphine implants, called by the brand name Probuphine. Before this, the FDA approved no implants for treating opioid addiction. Instead, medication for treating opioid addiction was only offered in injection or pill form. Similar to Probuphine, the naltrexone implant has been used in Europe for addiction treatment. The naltrexone implant holds promise for an FDA approval. However, there are key differences between the two options.

Buprenorphine is an opioid agonist medication, which means it is itself addictive. Even though it can be an effective opioid addiction treatment if used with medical guidance, it can also produce a high if abused. The FDA-approved Probuphine implant can be used to treat opioid addiction right away because a detox period is not required. Because the implant is within the patient's skin, the patient can't abuse it. Naltrexone, on the other hand, is an opioid antagonist medication, which means it is not addictive. It can't get patients high. However, the naltrexone implant can't be used before detox.

Let's look more closely at the naltrexone implant and how it differs from the buprenorphine implant.

What Is the Naltrexone Implant?

Naltrexone Implant Can Prevent Opioid Addiction

What Is an MAT?

To overcome drug dependence, many patients will choose a medically assisted treatment (MAT). Used in conjunction with addiction therapy and medical supervision of withdrawal side effects, MATs can provide the extra support needed for a successful recovery. MATs come in pills, which are taken orally, and injection or implant form which are administered in a doctor's office.

Hands With Medicine

Addictions to alcohol and opioid drugs (which include oxytocin, Vicodin, Percocet, morphine, heroin, and fentanyl) in particular often are treated with MATs.
These MATs include opioid agonist and antagonist-based medications.

Opioid agonist-based medications stimulate the same brain receptors as heroin, oxytocin, and other opioid drugs. They are used to treat the symptoms of opioid withdrawal, including vomiting, aches, sleeplessness, sweating, diarrhea, anxiety, and agitation, among others. With a doctor's supervision, opioid agonist-based MATs can help a patient ween off of opioid drugs.

Opioid antagonist-based medications suppress the receptors in the brain that cause a high or euphoria when someone takes these types of drugs. When a patient takes an opioid antagonist based-MAT, their craving for alcohol and opioids will be reduced. However, the symptoms of withdrawal must be treated before an opioid antagonist based-MAT can be used.

What Is an MAT Implant?

Opioid antagonist and agonist-based MATs have been used in the United States for decades to treat opioid addiction. They are commonly known by the names Narcan (naloxone) or Suboxone (naloxone and buprenorphine). The Probuphine implant is the only implant-type opioid addiction MAT available in the United States today.

Hand With MAT

An implant differs from other MATs because it does not have to be injected or consumed orally. Instead, it is inserted under the skin in a quick, out-patient procedure. After four to six months, the implant dissolves on its own. The patient now may receive another implant or select the oral or injection type instead.

Is There a Need for the Naltrexone Implant?

Broken Syringe

What Are the Benefits of an Implant?

The naltrexone implant has not been approved by the FDA. Is there a need for its approval in the US? Let's look at some benefits of an implant-type MAT first.

The implant may be better suited to patients than the injection or oral-form MATs for several reasons. The injection requires the patient to visit the doctor's office or an addiction support center regularly. People who work irregular hours, must travel for work, do not have reliable transportation, or are otherwise unable to receive the injection reliably will not be good candidates for an injection MAT. The pill has similar requirements; the patient must be able to take the pill at the same time every day. If the pill is lost or stolen, or if for other reasons the patient cannot take the pill at the correct time, then their recovery is jeopardized.

The implant provides the time-tested effectiveness of opioid antagonist MATs in a form with a reduced chance that a patient's treatment will be interrupted.

What Are the Benefits of Naltrexone Implants vs. Buprenorphine Implants?

Naltrexone Implant Can Prevent Opioid Addiction

Naltrexone implants might be a better choice for a patient than buprenorphine if the patient has already gone through the detox process but still wants the benefits of an implant. Some patients leaving detox centers or finishing buprenorphine-centered MATs can't consume or be exposed to opioids drugs or other opioid agonists. For this reason, the FDA-approved buprenorphine implant isn't for them.

The naltrexone implant currently used in Europe provides a detoxed patient with a steady dose of medication to support their recovery. Because they don't have to take a pill every day or have an injection regularly, the patient doesn't have to worry about forgetting to take or losing their pills or missing an injection appointment.

How Does the Naltrexone Implant Treat Opioid Addiction?

Nurse And Doctor

How Is the Implant Inserted?

The naltrexone implant is inserted through a small incision made in the skin over the patient's hip bone. The doctor places the pellet-shaped implant in the incision and closes the incision with surgical glue. The implant will slow-release naltrexone into the patient's body for up to six months. The implant can begin to work within thirty minutes. Since it is designed to dissolve in the patient's body, there is no need for removal.

Implant Insertion

Naltrexone can reduce a patient's craving for alcohol or opioid drugs. As an MAT, it assists with the recovery process; it alone is not a "cure" for addiction. Someone with an active addiction to opioids must have a doctor's supervision as they detox from the drug. The buprenorphine implant might be a better choice for this patient than the naltrexone implant.

Belly Scar

A good naltrexone implant candidate will have already gone through the withdrawal process. They must be interested in continuing their recovery with an MAT and ready to take part in therapy and additional supportive treatment if necessary.

The implant also can be a good choice for a patient who has tried oral or injection MATs and relapsed. If missed oral dosages or inability to schedule regular injections kept an inconsistent amount of naltrexone in the patient's system, then the implant could be a solution for administering naltrexone.

Is the Implant Dangerous?

Currently, the naltrexone implant is not recommended for patients who are pregnant or trying to get pregnant. Additional research is needed to find out if the drug can be passed on to a baby in the womb or come through the mother's breast milk.

The patient and the patient's family need to know treatment with an MAT does not guarantee that all drug cravings will stop; it only reduces them. A patient who has the implant might still want to consume drugs, especially if they are around friends who are doing drugs. If the patient takes opioid drugs after a long time at the amount they used in the past, they may inadvertently overdose.

Tablets In Question Mark

Another potential danger is the threat of the patient trying to remove the implant themselves. Unlike the case of the injection, which the patient cannot remove from their system after it's administered, or the pill which the patient can cease taking, a patient in psychological distress may try to remove the implant from beneath their skin. Not only will this interrupt the patient's naltrexone treatment, but it also risks the patient getting an infection in the incision's site.

More research on naltrexone's safety is likely to come in the future if demand for the implant in the United States grows.

What Are Some Common Side Effects of the Implant?

Woman With Headache

Some surprising common side effects reported include toothaches, pain in the larynx and esophagus, and back pain. Other common side effects reported include pain at the site of the incision, nausea, vomiting, headaches, and constipation.

Right after the insertion of the implant, the patient should keep an eye out for skin infection around the incision. While the patient should be able to return to work right after the insertion, they should avoid wearing pants or underwear that rubs at the incision site. If the incision is inflamed, irritated, or painful for over two days after the procedure, the patient should call their doctor and have the incision examined.


Opioid and alcohol addiction afflicts many people in the United States. As more resources become available to support recovery, more people will heal from their addictions. While the naltrexone implant has not been FDA approved, it's frequently used in Europe. The FDA approval of the buprenorphine implant is a sign that an approved naltrexone implant might be on its way to the United States. Together, these implants provide MAT options for recovering opioid addicts and alcoholics that did not exist in the past. Added to the current oral and injection treatments available, they can offer new hope to those in recovery.

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