Naltrexone (Revia, Vivitrol): Uses, MOA, Safety

What is naltrexone?

Naltrexone is an active ingredient used in the treatment of alcoholism and in dehabituation to opiates. The product ingredient is naltrexone hydrochloride (HCl).

In the United States, brand names mentioned for naltrexone include Vivitrol, Revia, and Depade.

How naltrexone works

Naltrexone is an opioid antagonist. It acts by competing with receptors located in the central nervous system and in the periphery, antagonizing the actions of exogenous opiates.

Therapeutic indications and uses

Based on the original content, naltrexone is used for:

• Alcoholism
• Opiate withdrawal, accompanied by other therapeutic measures

Dosage information from the original content

The original content lists oral naltrexone 50 mg/tablet and notes that treatment should only begin after a period of abstinence from narcotic drugs, verified by urinalysis.

Administration: Oral use. The source says it should be administered preferably with meals.

Contraindications listed in the source

• Hypersensitivity
• Severe renal and hepatic insufficiency
• Acute hepatitis
• Current dependence on opiates
• Concomitant use with opiates
• Positive opioid control or not passing the naloxone test

Warnings and precautions

• Liver and/or kidney failure
• Liver tests at the beginning and periodically during treatment
• In opiate addicts, a withdrawal syndrome may be triggered
• High doses used to cancel the blockage can cause acute poisoning, possibly fatal
• Opioids in cough, cold, or antidiarrheal preparations should not be used during treatment
• If opioid analgesics are needed in an emergency, higher doses may be required and respiratory depression may be deeper and longer; hospital monitoring may be necessary
• Children and adolescents under 18 years: not recommended in the source
• Elderly: safe use for opiate dependence has not been established

Liver and kidney considerations

The source states that naltrexone is contraindicated in severe liver failure and acute hepatitis. It also advises caution in hepatic insufficiency and recommends liver tests at the beginning and periodically during treatment.

For the kidneys, the source lists severe renal failure as a contraindication and advises caution in renal insufficiency.

Interactions listed in the source

The original content highlights the following interaction points:

• Association not recommended: opioid agonist analgesics, opioid agonist-antagonist analgesics, and opioids used in substitution treatment
• Association to be considered: barbiturates and benzodiazepines
• Drowsiness and lethargy have been reported after administration with thioridazine
• With acamprosate, naltrexone was observed to significantly increase plasma levels of acamprosate in one safety and tolerability study
• Interactions with other psychotropic drugs such as disulfiram, amitriptyline, doxepin, lithium, clozapine, and benzodiazepines were not investigated in the source

Pregnancy and breastfeeding

Pregnancy

Animal studies have shown reproductive toxicity. The potential risk in humans is unknown. The source says it should only be administered when, in medical judgment, the potential benefits outweigh the possible risks.

Breastfeeding

It is not known whether naltrexone or 6-beta-naltrexol are excreted in breast milk. The source states that breastfeeding is not recommended during treatment.

Effects on driving and machines

The influence of naltrexone on the ability to drive and use machines is described in the source as small or moderate.

Adverse reactions and side effects listed in the source

The following adverse reactions are mentioned in the original content:

• Headache
• Sleep disorder
• Restlessness
• Nervousness
• Abdominal pain and abdominal cramps
• Nausea and tendency to vomit
• Muscle and joint pain
• Weakness
• Thirst
• Dizziness and vertigo
• Chills and increased perspiration
• Increased tearing
• Chest pain
• Diarrhea or constipation
• Urine retention
• Rash
• Loss of appetite
• Delayed ejaculation and decreased sexual potency
• Anxiety
• Increased energy level
• Depression, irritability, and mood swings

What to verify in the official leaflet

If you are comparing products or checking whether naltrexone is appropriate for a specific situation, the most useful details to confirm in the official leaflet or with a pharmacist are:

• The exact formulation and brand name
• Whether the product is oral or injectable
• The approved indication for that specific product
• Any liver, kidney, or opioid-related warnings
• Interaction warnings with pain medicines, cough/cold products, or antidiarrheals
• Pregnancy and breastfeeding guidance

FAQ

Sources and references

The original content states that it was written using clinical and molecular information from medicines authorized and marketed in the United States under the Unique Ingredient Identifier (UNII) by the FDA Substance Registration System (SRS) and the United States Pharmacopeia (USP).

• FDA Medication Guide database
• UNII: 5S6W795CQM
• ChemIDplus
• DrugPortal
• PubChem CID: 5360515
• NCI Thesaurus: C62055