Naltrexone is a medication approved by the U.S. Food and Drug Administration (FDA) for the treatment of Alcohol Use Disorder (AUD). Classified as an opioid antagonist, it works by blocking certain brain receptors. Its primary purpose is to reduce heavy drinking episodes and decrease the motivation to consume alcohol. Naltrexone is a pharmacological option used to support individuals in recovery.
How Naltrexone Works
Naltrexone’s effectiveness in managing Alcohol Use Disorder is rooted in its action as an opioid receptor antagonist. Specifically, the medication targets the mu-opioid receptors within the central nervous system. These receptors are part of the brain’s natural reward pathway, which is activated by the release of the body’s own naturally produced opioids, called endorphins.
When a person consumes alcohol, it indirectly causes the release of these endorphins, which then bind to the mu-opioid receptors. This binding leads to the feelings of pleasure, euphoria, and reward that reinforce the desire to drink more alcohol. Naltrexone competitively binds to these same receptors with a higher affinity than the endorphins.
By occupying the mu-opioid receptors, naltrexone blocks the endorphins from attaching and activating the reward pathway. This dampens the reinforcing effects of alcohol, making the experience less pleasurable. The resulting reduction in euphoric feeling translates into decreased urges and cravings, weakening the cycle of heavy drinking. This suppression allows the individual to engage more effectively in behavioral treatments.
Understanding the 100 mg Dosage and Delivery Methods
The standard, FDA-approved oral dosage of naltrexone for Alcohol Use Disorder is a 50 mg tablet taken once daily. This dosage is the most common and widely prescribed regimen for most patients. It has been shown to achieve nearly complete blockade of the mu-opioid receptors, which reduces the reinforcing effects of alcohol.
A 100 mg daily dosage is sometimes encountered in specific clinical settings, though it is not the standard recommendation. This higher dose was studied in the large COMBINE clinical trial and found to be more efficacious than placebo in increasing abstinence days. Clinicians may consider 100 mg for patients who have a partial response to the 50 mg dose or those with more severe alcohol cravings.
Naltrexone is available through two primary delivery methods: the daily oral tablet and an extended-release injectable form, known by the brand name Vivitrol. The oral tablet is taken once a day and relies on the patient’s consistent adherence to the daily regimen. The injectable formulation, on the other hand, consists of a 380 mg dose administered intramuscularly once every four weeks by a healthcare professional.
The injectable form provides a steady release over a month, significantly improving compliance by eliminating the need for daily dosing. While the oral form offers flexibility, the injection may be preferred for patients who struggle with adherence. Both delivery methods target the mu-opioid receptors to reduce heavy drinking and cravings, differing only in convenience and administration supervision.
Safety Considerations and Adverse Effects
Patients must be aware of potential side effects and contraindications before starting naltrexone treatment. Common adverse effects are typically gastrointestinal, including nausea, headache, dizziness, and joint or muscle pain. Nausea is frequently reported but often lessens after the first few days or weeks of starting the medication.
A significant safety consideration involves the interaction between naltrexone and opioids. Since naltrexone blocks opioid effects, taking it while physically dependent on opioids will precipitate a severe withdrawal syndrome. Patients must be opioid-free for at least seven to ten days before starting treatment. Furthermore, patients must be cautious about using large doses of opioids to overcome the blockade, as this can lead to life-threatening overdose or death once naltrexone effects wear off.
Because naltrexone is metabolized by the liver, there is a risk of liver toxicity, though this is rare at the standard 50 mg daily dose. Healthcare providers often perform baseline liver function tests (LFTs) and may recheck them periodically, especially when higher doses are used. Patients should look for signs of liver problems, such as persistent stomach pain, dark urine, or yellowing of the skin or eyes, and seek immediate medical attention if these symptoms appear.
The Role of Naltrexone in Recovery
Naltrexone is not intended to be a standalone treatment but rather a component of a comprehensive Medication-Assisted Treatment (MAT) plan for Alcohol Use Disorder. The medication reduces the biological drive to drink, creating a window of opportunity for therapeutic work. This approach acknowledges that AUD has biological roots that can be addressed with medication, while also requiring behavioral change.
The best outcomes are seen when naltrexone is used alongside psychosocial interventions, such as counseling, cognitive-behavioral therapy, and support groups. By diminishing alcohol cravings and reinforcing effects, naltrexone helps patients maintain abstinence or significantly reduce heavy drinking days. This reduction allows the individual to focus on developing coping strategies and addressing underlying issues. The combined strategy of medication and therapy provides a holistic pathway to sustained recovery.