What Is Naltrexone?

NIDA StudyNaltrexone is a medication approved by the Food and Drug Administration (FDA) and used in medication-assisted treatment (MAT) to treat both opioid and alcohol use disorders. It comes in a pill form or as an injectable.

The pill form of naltrexone (ReVia, Depade) can be taken at 50 mg once per day. The injectable extended-release form of the drug (Vivitrol) is administered at 380 mg intramuscular once a month.

Naltrexone can be prescribed by any health care provider who is licensed to prescribe medications. To reduce the risk of precipitated withdrawal, patients are warned to abstain from illegal opioids and opioid medication for a minimum of 7-10 days before starting naltrexone. If switching from methadone to naltrexone, the patient has to be completely withdrawn from the opioids.

How Naltrexone Works

Naltrexone blocks the euphoric and sedative effects of drugs such as heroin, morphine, and codeine. It works differently in the body than buprenorphine and methadone, which activate opioid receptors in the body that suppress cravings. Naltrexone binds and blocks opioid receptors and is reported to reduce opioid cravings. There is no abuse and diversion potential with naltrexone.

If a person relapses and uses the problem drug, naltrexone prevents the feeling of getting high. People using naltrexone should not use any other opioids or illicit drugs; drink alcohol; or take sedatives, tranquilizers, or other drugs.

Patients on naltrexone may have reduced tolerance to opioids and may be unaware of their potential sensitivity to the same, or lower, doses of opioids that they used to take. If patients who are treated with naltrexone relapse after a period of abstinence, it is possible that the dosage of opioid that was previously used may have life-threatening consequences, including respiratory arrest and circulatory collapse.

As with all medications used in medication-assisted treatment (MAT), naltrexone is to be prescribed as part of a comprehensive treatment plan that includes counseling and participation in social support programs.

Naltrexone for Opioid Use Disorders

Extended-release injectable naltrexone is approved for treatment of people with opioid use disorder. It can be prescribed by any healthcare provider who is licensed to prescribe medications, special training is not required. It is important that medical managed withdrawal (detoxification) from opioids be completed at least 7 to 10 days before extended-release injectable naltrexone is initiated or resumed. Research has shown that naltrexone decreases reactivity to drug-conditioned cues and decreases craving. Patients who have been treated with extended-release injectable naltrexone may have reduced tolerance to opioids and may be unaware of their potential sensitivity to the same, or lower, doses of opioids that they used to take. Extended-release naltrexone should be part of a comprehensive management program that includes psychosocial support.

Side Effects of Naltrexone

People taking naltrexone may experience side effects, but they should not stop taking the medication. Instead, they should consult their health care provider or substance misuse treatment practitioner to adjust the dose or change the medication. Some side effects include:

  • Upset stomach or vomiting
  • Diarrhea
  • Headache
  • Nervousness
  • Sleep problems/tiredness
  • Joint or muscle pain

Suboxone vs. Naltrexone

Both Suboxone and Naltrexone are equally effective in treating addiction to heroin and prescription painkillers.

Though both Suboxone and Naltrexone medications curb the desire and cravings to use heroin or other opioids, they differ in a few key ways:

Suboxone, which is buprenorphine and naloxone, is a daily pill that is taken before a person goes through detox or continued after detox and during recovery. It’s considered a replacement medication, like methadone, because it is a partial agonist. The downside to Suboxone, though, is that it must be taken orally on a daily basis.

Vivitrol, the brand name for naltrexone, is a narcotic blocker or what’s known as an opioid antagonist. This medication, which is as effective as Suboxone, is a monthly injection. A potential downside for patients, though, is that it can only be administered after opioid withdrawal takes place.