naltrexone extended release

Adjunctive therapy

Brands: Vivitrol

Last reviewed 2026-02-12

Reviewed by PsychMed Editorial Team.

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Quick answers

What is naltrexone extended release?
Extended-release naltrexone (brand Vivitrol) is a monthly intramuscular injection of an opioid receptor antagonist. It is indicated for alcohol dependence and for opioid dependence relapse prevention after detoxification (label).
What is Vivitrol?
Vivitrol is a brand name for naltrexone extended release.
What is Vivitrol (naltrexone extended release) used for?
Label indications include: Alcohol dependence; opioid relapse prevention after detoxification (label).
What drug class is Vivitrol (naltrexone extended release)?
Monthly extended-release injectable naltrexone (opioid antagonist) used for alcohol dependence and for opioid relapse prevention after detoxification. Requires an opioid-free interval to avoid precipitated withdrawal and carries important injection-site, hepatotoxicity, and overdose-vulnerability warnings (label/guideline).
What strengths does Vivitrol (naltrexone extended release) come in?
Injectable suspension containing 380 mg of naltrexone in a microsphere formulation (single-dose vial) (label).

Snapshot

Class: Adjunctive therapy
Common US brands: Vivitrol
Therapeutic drug monitoring not routinely recommended.
Last reviewed: 2026-02-12

Label indications

Alcohol dependence; opioid relapse prevention after detoxification (label).

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Clinical Highlights

Extended-release naltrexone (brand Vivitrol) is a monthly intramuscular injection of an opioid receptor antagonist. It is indicated for alcohol dependence and for opioid dependence relapse prevention after detoxification (label). A core safety requirement is that patients must be opioid-free before initiation. Labeling recommends an opioid-free duration of at least 7–10 days to avoid precipitated opioid withdrawal that may require hospitalization (label).

Because it is a long-acting injection, adherence is less dependent on daily pill-taking than oral naltrexone. At the same time, once injected it cannot be “removed,” and missed visits can create predictable gaps in opioid blockade (label/clinical).
For OUD, an important practical distinction versus buprenorphine is the need to complete detoxification first. In the X:BOT trial, extended-release naltrexone and buprenorphine/naloxone were similarly effective among patients who successfully initiated treatment, but more patients failed induction onto extended-release naltrexone because of the detoxification barrier (trial).
Label warnings include overdose vulnerability (reduced tolerance during treatment and after discontinuation), hepatotoxicity, severe injection site reactions (including necrosis), and depression/suicidality monitoring (label/clinical).
The compare view, extended-release naltrexone evidence feed, and extended-release naltrexone print page support shared decision-making when alcohol use disorder (AUD) and opioid use disorder (OUD) are part of the same clinical picture.

Dosing & Formulations

Vivitrol is supplied as an injectable suspension containing 380 mg of naltrexone in a microsphere formulation (single-dose vial) (label). The recommended dose is 380 mg as a deep intramuscular gluteal injection every 4 weeks (once a month), alternating buttocks each injection (label).

Vivitrol must only be administered as a deep intramuscular gluteal injection using the carton components; other routes (e.g., intravenous or subcutaneous) are not appropriate (label).
Transition planning is clinically important when switching from opioid agonists (methadone or buprenorphine), because patients may remain vulnerable to precipitated withdrawal for up to two weeks (label/clinical).

Monitoring & Risks

Overdose vulnerability is a key risk: opioid tolerance is reduced during treatment and after discontinuation, and attempts to overcome blockade can result in fatal opioid overdose. Labeling strongly considers prescribing naloxone for emergency overdose treatment (label). Severe injection-site reactions including abscess, cellulitis, and necrosis have been reported; patients with concerning reactions require medical evaluation (label/clinical).

Hepatotoxicity has been observed; baseline and follow-up liver monitoring is common, especially when alcohol-related liver disease is present (label/clinical).
Depression and suicidality monitoring is recommended, particularly in patients with comorbid mood disorders (label/clinical).

Drug Interactions

Opioid-containing medications (analgesics, antidiarrheals, cough suppressants) will be blocked and may be ineffective. Acute pain and perioperative planning often requires advance coordination (label/clinical). Combining extended-release naltrexone with other hepatotoxic exposures may increase liver risk; clinicians often review alcohol use, viral hepatitis, and medication lists as part of monitoring (clinical).

Practice Notes

Extended-release naltrexone can be a good fit for patients who prefer an opioid-antagonist approach and can reliably complete detoxification and attend monthly injections; readiness and follow-up reliability are practical determinants of success (clinical). For alcohol use disorder, guidelines include naltrexone among first-line pharmacotherapies; clinicians often pair it with structured follow-up and behavioral treatments (guideline).

References

Vivitrol (naltrexone FOR Extended Release Injectable Suspension) Prescribing Information — DailyMed (2026)
The ASAM National Practice Guideline for the Treatment of Opioid Use Disorder: 2020 Focused Update — Journal of Addiction Medicine (2020)
TIP 63: Medications for Opioid Use Disorder — SAMHSA (2021)
Comparative Effectiveness OF Extended Release Naltrexone Versus Buprenorphine Naloxone FOR Opioid Relapse Prevention (x:bot): A Multicentre, Open Label, Randomised Controlled Trial — The Lancet (2018)
The American Psychiatric Association Practice Guideline for the Pharmacological Treatment of Patients With Alcohol Use Disorder — American Journal of Psychiatry (2018)