Naltrexone

REVIA

Open Naltrexone in the interactive console ↗

Pronunciation: nal-TREX-oen

Naltrexone ballicule: receptor binding, kinetics and half-life diagram — Mechanism of action: Naltrexone ballicule

Naltrexone ReVia mascot mnemonic cartoon — Visual mnemonic: Naltrexone mascot
**“Nail tracks in Reverse”**
dilated pupils → opioid blocker

What it isCompetitive mu opioid antagonist; alcohol and opioid use disorder.

Why this oneOral tablets reduce heavy drinking in alcohol use disorder without requiring abstinence to start. The monthly injection (VIVITROL, a separate product) lessens reliance on daily pills, but is labeled for patients able to abstain from alcohol first.

What limits itBlocks opioid analgesia entirely and precipitates withdrawal, so seven to ten days opioid-free are required first.

Pearls

Oral form fails in OUD unless adherence is mandated.
Mortality benefit in OUD unproven, unlike buprenorphine and methadone.
Not a controlled substance.
Monitor liver enzymes; hepatotoxicity reported.

Naltrexone molecular structure (skeletal formula) — Molecular structure: Naltrexone

FDA-approved for

opioid use disorder (1984)
alcohol use disorder (1994)

Off-label

self-injurious behavior
weight loss (low-dose)
impulse-control disorders

Principal riskPrecipitated withdrawal; blocks opioid analgesia

Classes and tags

Clinical profile

Therapeutic safety burden1 / 4

Overdose danger1 / 4

Weight-gain liability0 / 4

Sedation liability0 / 4

QT / Torsades0 / 4

Direct muscarinic antagonism0 / 4

Embryofetal risk1 / 4

Legacy pregnancy categoryC

Defining liabilityGenerally tolerated at therapeutic doses; clinically important risks are agent-specific and increase with interactions or organ impairment.

FDA label

Read the full label on DailyMed ↗

NO BOXED WARNINGS

FDA dosing	Population	Start	Target	Max
Alcohol dependence	Adults	50 mg QD	50 mg QD	50 mg QD
Opioid dependence (blockade)	Adults	25 mg once; if no withdrawal, 50 mg QD	50 mg QD	50 mg QD

Renal Undefined

Hepatic Undefined

Higher risk of hepatocellular injury with single doses above 50 mg

Instructions

Patient must be opioid-free (incl. tramadol) 7–10 days before starting
Consider naloxone challenge test if occult opioid dependence suspected; do not start if positive
Do not start in acute opioid withdrawal or positive opioid urine screen
Alternative supervised schedules (e.g., 100 mg every other day, 150 mg every third day) reduce blockade

Available strengths

tab 50 mg

Contraindications

Patients receiving opioid analgesics
Current opioid dependence, incl. maintenance on agonists (methadone) or partial agonists (buprenorphine)
Acute opioid withdrawal
Failed naloxone challenge test or positive opioid urine screen

Cautions

Dose-related hepatocellular injury (esp. doses above recommended)
Precipitated / exacerbated opioid withdrawal in non-opioid-free patients
Vulnerability to opioid overdose after treatment (reduced tolerance) or attempts to overcome blockade
Depression and suicidality reported
Withdrawal/deaths reported with ultra-rapid opioid detoxification

Adverse reactions

Nausea
Headache
Dizziness
Nervousness
Fatigue
Insomnia
Vomiting
Anxiety
Somnolence
Abdominal pain/cramps (opioid-dependent patients)

Pregnancy Category C; increased early fetal loss in animals at high doses; use only if benefit justifies risk

Lactation Undefined

Cost

Naltrexone (REVIA)

What pharmacies pay · NADAC 9/30/26

Strength		#/mo	generic $/mo	CostPlus
50 mg	tab	30 qd	$34.12	offered

Other forms: Naltrexone ER injection (VIVITROL)

Available combined with: naltrexone / bupropion

Generic entry1998

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Memory aids: interaction avatars

no kinetic interactions

Open Naltrexone in the interactive console ↗

Self-check

How long opioid-free is required before naltrexone?
Seven to ten days.
Must alcohol abstinence precede naltrexone treatment for alcohol use disorder?
No.