Naltrexone ER injection

VIVITROL

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Pronunciation: nal-TREX-oen

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

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

What it isA monthly IM mu- and kappa-opioid antagonist; alcohol use disorder and relapse prevention in opioid use disorder.

Why this oneIt removes daily adherence from oral naltrexone and cannot be diverted or misused as an opioid.

What limits itIt requires 7-14 opioid-free days first; injecting sooner can precipitate withdrawal, and the medication blocks opioid analgesia.

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

FDA-approved for

alcohol use disorder (2006)
opioid use disorder (relapse prevention) (2010)

FDA label

Read the full label on DailyMed ↗

FDA dosing	Population	Start	Target	Max
Alcohol dependence	Adults (able to abstain before initiation)	380 mg IM q4 weeks	380 mg IM q4 weeks	380 mg q4 weeks
Prevention of relapse to opioid dependence after detox	Adults (opioid-free ≥7–10 days)	380 mg IM q4 weeks	380 mg IM q4 weeks	380 mg q4 weeks

Renal Caution in moderate to severe renal impairment; no adjustment for mild

Hepatic No adjustment for mild–moderate; not evaluated in severe

Administer every 4 weeks (monthly)

Instructions

Deep IM gluteal injection only; prepared and administered by a healthcare provider
Ensure opioid-free 7–10 days before first dose
Alternate buttocks with each injection; do not give IV or SC

Available strengths

inj 380 mg
tab 25, 50, 100 mg

Contraindications

Patients receiving opioid analgesics
Patients with current physiologic opioid dependence
Patients in acute opioid withdrawal
Any individual who has failed the naloxone challenge test or has a positive urine screen for opioids

Cautions

Vulnerability to opioid overdose (reduced tolerance)
Injection site reactions (some severe, incl. necrosis)
Precipitation of opioid withdrawal
Hepatotoxicity
Depression and suicidality
Eosinophilic pneumonia
Hypersensitivity/anaphylaxis

Adverse reactions

Nausea
Vomiting
Injection site reactions
Muscle cramps
Dizziness/syncope
Somnolence/sedation
Decreased appetite
Hepatic enzyme abnormalities (opioid dependence)
Injection site pain
Nasopharyngitis
Insomnia
Toothache

Pregnancy Insufficient human data; animal data show early fetal loss at high exposures

Lactation Naltrexone and 6β-naltrexol present in human milk; no data on breastfed infant

Cost

Naltrexone ER injection (VIVITROL)

Strength		#/mo	generic $/unit	CostPlus
380 mg	inj	per unit		not offered

NADAC is a voluntary CMS survey of what retail community pharmacies pay for the drugs they stock. Naltrexone ER injection is administered under clinical supervision and dispensed outside retail pharmacies, so it rarely appears on surveyed invoices.

Other forms: Naltrexone (REVIA)

Available combined with: naltrexone / bupropion

⚠ BOXED WARNINGS

Addiction, abuse and misuse
Life-threatening respiratory depression
Risk from concomitant use with benzodiazepines

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.

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Memory aids: interaction avatars

no kinetic interactions

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