Generic
Naltrexone
4 brands available in the market
At a glance
Naltrexone is an opioid antagonist used for opioid dependence and alcohol addiction. It blocks the euphoric effects of opioids and alcohol to reduce craving.
Description
Naltrexone acts as a competitive antagonist at opioid receptor sites. It blocks the action of opioids and precipitates withdrawal symptoms in opioid-dependent individuals.
Indications
- Opioid dependence (prevention of relapse after detoxification)
- Alcohol addiction
Therapeutic class
Opioid Antagonist
Pharmacological class
Opioid Receptor Antagonist
Pharmacology
Naltrexone acts as a competitive antagonist at opioid receptor sites. It blocks the action of opioids and precipitates withdrawal symptoms in opioid-dependent individuals.
Mechanism of action
Blocks euphoric effects of opioids and alcohol to reduce craving.
Dosage
Opioid Dependence:
- Oral: 25 mg initially, observe for 1 hr, then 50 mg once daily (from day 2)
- IM: 380 mg every 4 weeks (maintenance)
Alcohol Addiction:
- Oral: 50 mg once daily for <12 weeks
- IM: 380 mg every 4 weeks (maintenance)
Administration
- Swallow tablet whole; do not chew, crush or break
- Take at the same time each day
- May be taken with or without food
Missed dose
If you miss a dose, take it as soon as you remember; skip if it's almost time for next dose; do not double the dose.
Side effects
Common Side Effects:
- Joint pain
- Fainting
- Decreased libido
- Muscle pain
- Insomnia
- Increased thirst
- Decreased sexual function
- Fatigue, nausea, abdominal pain, diarrhea
Precautions & warnings
- Patient must be opioid-free for 7-10 days before use
- Naloxone challenge test must be negative
- Monitor liver function regularly
- Caution while driving (may cause fatigue or dizziness)
Contraindications
- Patients concurrently dependent on opioids
- Acute hepatitis or hepatic failure
- Acute opioid withdrawal
- Patients on therapeutic opioid analgesics
Drug interactions
- May reduce effects of opiate-containing preparations (cough, cold, diarrhea, pain medicines)
- Increased or decreased levels with drugs altering hepatic metabolism
- Increased hepatotoxic effects with disulfiram
- Increased lethargy and somnolence with thioridazine
- May increase insulin requirements
Food interactions
No harmful interaction with alcohol.
Use in pregnancy
Use in Pregnancy: Naltrexone may be unsafe during pregnancy; animal studies show evidence of fetal harm.
Pregnancy Category: C — always consult a doctor before taking during pregnancy.
Use in lactation
Use in Lactation: Naltrexone is probably safe during breastfeeding; no significant risk to baby.
Pediatric use
Safety and efficacy not established in children.
Geriatric use
Elderly may require dose adjustment.
Renal / hepatic impairment
Renal Impairment: Caution in kidney disease; dose adjustment may be needed.
Hepatic Impairment: Caution in liver disease; dose adjustment may be needed; monitor liver function regularly.
Overdose effects
Overdose may cause opioid withdrawal symptoms; symptomatic treatment.
Storage conditions
Store in a dry place, away from light; keep out of reach of children.
Chemical structure
Naltrexone