Opioid Antagonist·Addiction Medicine

Naltrexone

TGA/PBS — Alcohol dependence within a comprehensive treatment program; adjunctive relapse-prevention therapy in formerly opioid-dependent patients who have ceased opioids

PBSPBS streamlinedAUD / OUDRevia50 mg tablet+3

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At a glance

Max Dose

50 mg OD

Half-life

4 h; metabolite 13 h

Caution: Hepatotoxic

RISK

High risk: Opioid Block

HIGH

Cautions

Avoid / Cautions

Contraindicated with opioid analgesics, current opioid dependence, acute opioid withdrawal, positive opioid screen or failed naloxone challenge, acute hepatitis or liver failure, and hypersensitivity. Caution in renal impairment, active liver disease, pregnancy, and lactation.

Where it stands

Rapid Summary

Overview

Opioid antagonist used within comprehensive treatment for alcohol dependence and as adjunctive relapse-prevention therapy after opioid cessation. It blocks opioid effects rather than directly treating withdrawal.

Clinical Focus

Confirm the patient is opioid-free for 7-10 days before starting. If opioid exposure is uncertain, use urine testing and/or a naloxone challenge; starting too early can precipitate withdrawal.

Bottom Line

Naltrexone is useful for alcohol dependence and selected opioid-relapse prevention, but it requires verified opioid washout, careful hepatic assessment, and clear counselling about opioid blockade and overdose risk.

Formulation & Access

Brand Names

Revia

Oral Routes

Tablets (50 mg).

Prescribing & PBS

Authority Required (STREAMLINED PBS), item 8370M, for listed alcohol-dependence and opioid-relapse-prevention restrictions. Check the current PBS restriction wording before prescribing.

Indications & Use

Primary

PBSTGA

TGA/PBS — Alcohol dependence within a comprehensive treatment program; adjunctive relapse-prevention therapy in formerly opioid-dependent patients who have ceased opioids.

Off-Label

OFF

Weight loss (combined with bupropion).

Clinical Place

AUD: useful where opioid analgesia is not needed and hepatic status is acceptable. OUD: oral naltrexone is not routine first-line maintenance because retention/compliance are poor; reserve for selected motivated/supervised patients after verified opioid cessation.

Quick reference

Class & Role

Opioid Antagonist — Potent, long-acting mu-opioid receptor antagonist.

Route / Formulation

Tablets (50 mg). (Revia)

Usual Dose & Max

Alcohol dependence: PO 50 mg once daily. Opioid-dependence relapse prevention: initiate only after opioid-free 7-10 days; consider 25 mg test dose then 50 mg daily if no withdrawal.

Key Indication Doses

AUD: 50 mg once daily within a comprehensive treatment program. OUD relapse prevention: only after verified opioid washout; urine opioid screen or naloxone challenge if uncertain.

Best Uses

Naltrexone is an opioid antagonist used for alcohol dependence and relapse prevention, but must have complete opioid washout before starting and is hepatotoxic at high doses.

Key Risks

Neurological: Precipitated opioid withdrawal. HIGH — Nausea, headache, dizziness, severe insomnia. Hepatic: Dose-dependent hepatotoxicity and transaminitis (usually at doses > 50mg, but monitor all patients). Psychiatric: Depression, anxiety.

Key Interactions

Blocks opioid analgesia. Attempts to overcome blockade can cause fatal opioid overdose; emergency opioid analgesia may require higher doses with deeper/prolonged respiratory depression. Avoid combined hepatotoxic risk unless benefit clearly outweighs risk.

Monitoring

Verify opioid-free 7-10 days before initiation; use urine opioid screen or naloxone challenge if uncertain. Check baseline/clinically indicated LFTs and counsel on opioid blockade/medical alert information.

Clinical Pearl

You must wait at least 7 days after the last short-acting opioid (or 10-14 days for methadone) before giving the first dose of Naltrexone. Perform a 'Naloxone Challenge' test first if unsure.

Access

PBS streamlinedRevia8370M

Brand: Revia
PBS status: PBS streamlined
PBS item: 8370M
Formulation: Tablets (50 mg).

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