Once-A-Month Naltrexone Injection Effective

Improves Long-Term Treatment Outcomes

Vivitrol. Alkermes

The medication naltrexone has become one of the most effective pharmaceutical treatments for alcoholism because it works to reduce the chemical effects that alcohol has on the brain.

One of only three medications approved for the treatment of alcohol dependence, naltrexone has been used for years to help people who have already stopped drinking to avoid relapse.

Naltrexone has also been effective in treating people who have become addicted to prescription opioids, heroin and is being researched in cocaine use disorders. It does so by blocking the effect that opioids have on the pleasure centers of the brain. Naltrexone in lower doses is also used to treat pain caused by conditions like fibromyalgia and chronic fatigue syndrome.

If you or a loved one are struggling with substance use or addiction, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.

For more mental health resources, see our National Helpline Database.

The Problems With a Daily Pill

For the treatment of alcohol use disorders, naltrexone was originally prescribed as a daily pill usually taken about 12 weeks, and naltrexone in pill form - marketed as Revia and Depade - is still widely used.

However, there is a inherent problem with the pill form of naltrexone - for it to work, the people who it is designed to help must actually take the drug every day. For those struggling with the effects of alcohol withdrawal and alcohol use disorders, compliance with taking a daily dose can be problematic.

Long-Acting, Once-a-Month Injection

This problem was addressed when researchers began to look at a new form of naltrexone that could be injected once and be slowly released into the system for a month.

One of those studies was conducted at the University of North Carolina at Chapel Hill and involved 624 patients who were being treated for alcohol use disorders in hospitals, V.A. clinics and medical centers in the United States.

All of the patients were actively drinking, but being treated for alcoholism.

Reduction of Heavy Drinking Days

The participants were injected with 380 mg. of long-acting naltrexone, 190 mg. of naltrexone, or given a placebo injection. The injections were given monthly and both groups received 12 low-intensity psychosocial intervention sessions.

The study found that a 380 mg dose of naltrexone resulted in a 25% reduction of heavy drinking days, while a 190 mg dose reduced heavy drinking days 17%.

The researchers determined that men responded to naltrexone treatment more than women and that those patients who came into the study with some abstinent time saw greater treatment effects.

Some Side Effects, But Mild

Of those taking the 380-mg dose, 14.1% dropped out of the treatment due to side-effects, including nausea, headache and fatigue. Only 6.7% of the group receiving 190 mg discontinued treatment due to adverse side effects.

The North Carolina study was one of the largest trials of subjects treated with a medication for alcohol dependence. The conclusions of the researchers were that long term release naltrexone was well tolerated and significantly reduced heavy drinking in actively drinking patients.

Vivitrol Approved by the FDA

The study also found that the long-acting form of naltrexone could improve treatment strategies for alcoholics by eliminating the medication compliance issue and providing a "predictable pharmacologic foundation for treatment."

This study and others were a factor in the U.S. Food and Drug Administration decision in April 2006 to approve the once-a-month naltrexone treatment - marketed as Vivitrol - for use as a treatment for alcohol dependence.


Garbutt, JC, et al. "A Randomized Controlled Trial Of Long-acting Injectable Naltrexone for Alcohol Dependence." Journal of the American Medical Association April 2005

U.S. National Library of Medicine. "Naltrexone Injection Drugs, Herbs and Supplements. November 2010

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