Extended release naltrexone is a medication-assisted treatment for individuals managing substance use disorders. It helps people maintain abstinence and reduce cravings associated with certain substance dependencies.
What is Extended Release Naltrexone?
Extended release naltrexone, often known by the brand name Vivitrol, is a specialized formulation of the drug naltrexone. The “extended release” aspect means it is designed to deliver the medication gradually over an extended period. This particular form is an injectable suspension, typically administered once a month.
This monthly injection differentiates it from the daily oral tablet form of naltrexone. The sustained release helps to ensure consistent medication levels in the body, reducing the need for daily adherence and potentially improving treatment consistency for individuals.
How It Affects the Body
Naltrexone functions as an opioid receptor antagonist. This means it binds to and blocks opioid receptors in the brain, primarily the mu-opioid receptors. By occupying these receptors, naltrexone prevents opioids from binding and producing their typical effects, such as euphoria and physical dependence.
The medication also works to reduce cravings for both opioids and alcohol. While the exact mechanism for craving reduction is still being explored, it is thought to involve modulating the brain’s reward pathways, making substance use less appealing. Naltrexone itself is not an opioid and does not cause physical dependence or withdrawal symptoms.
Treating Substance Use Disorders
Extended release naltrexone is approved by the FDA for treating Opioid Use Disorder (OUD) and Alcohol Use Disorder (AUD). For OUD, it helps to prevent relapse by blocking the effects of opioids. This blockade means that if a person uses opioids, they will not experience the euphoric effects, which can reduce the motivation to continue use.
For AUD, naltrexone helps reduce heavy drinking days and cravings for alcohol. It works by blocking the rewarding effects associated with alcohol consumption, which can lessen the desire to drink. This medication is part of a comprehensive treatment plan that includes counseling and psychosocial support.
Receiving the Treatment
Extended release naltrexone is administered as a deep intramuscular injection by a healthcare professional. The injection is typically given in the gluteal muscle (buttocks) and is usually repeated once every four weeks or once a month. Healthcare providers often alternate between the right and left buttocks for subsequent injections to prevent irritation.
Side effects may occur following the injection. These can include pain, tenderness, swelling, or redness at the injection site. Other side effects include nausea, headache, dizziness, fatigue, and muscle cramps. Nausea is more common after the first injection and usually subsides within a few days.
Key Safety Information
Before starting extended release naltrexone, individuals must be opioid-free for a specific period, typically a minimum of 7 to 10 days, to avoid precipitated withdrawal. Precipitated withdrawal can be severe and may require hospitalization, occurring when naltrexone rapidly displaces opioids from receptors in someone who is still physically dependent.
The medication is contraindicated in individuals receiving opioid analgesics, those with current physiological opioid dependence, or those in acute opioid withdrawal. It is also not recommended for patients with acute hepatitis or liver failure. There is an increased risk of opioid overdose if a person attempts to overcome the naltrexone block by using large amounts of opioids, or if they relapse after treatment cessation, as their opioid tolerance may be reduced. Close medical supervision and full disclosure of all medications to healthcare providers are important for safe treatment.