Naltrexone Dosage

Medically reviewed by Drugs.com. Last updated on Feb 13, 2024.

Applies to the following strengths: 50 mg; 380 mg; 1.5 mg; 4.5 mg

Usual Adult Dose for:

Alcohol Dependence
Opiate Dependence

Additional dosage information:

Renal Dose Adjustments
Liver Dose Adjustments
Dose Adjustments
Precautions
Dialysis
Other Comments

Usual Adult Dose for Alcohol Dependence

Oral:
Average dose: 50 mg orally once a day
Duration of therapy: 12 weeks

Intramuscular:
380 mg intramuscularly every 4 weeks/once a month

Comments:

There is no data specifically addressing switching from buprenorphine or methadone to naltrexone, however some patients have reported severe manifestations of precipitated withdrawal when switched from an opioid agonist to opioid antagonist therapy.
Patients switching from buprenorphine or methadone may be vulnerable to precipitated withdrawal for up to 2 weeks.
Be prepared to manage withdrawal symptomatically with non-opioid medications.
To achieve best possible results, implement compliance-enhancing techniques, especially medication compliance

Usual Adult Dose for Opiate Dependence

Oral:
Initial dose: 25 mg orally once a day
Maintenance dose: 50 mg orally once a day (if no withdrawals on 25 mg/day)

Intramuscular:
380 mg intramuscularly every 4 weeks/once a month

Comments:

There is no data specifically addressing switching from buprenorphine or methadone to naltrexone, however some patients have reported severe manifestations of precipitated withdrawal when switched from an opioid agonist to opioid antagonist therapy.
Patients switching from buprenorphine or methadone may be vulnerable to precipitated withdrawal for up to 2 weeks.
Be prepared to manage withdrawal symptomatically with non-opioid medications.
This drug is of value only as a part of a comprehensive management plan that includes measures to ensure the patient takes this medication.

Use(s): Blockade of the effects of exogenously administered opioids

Renal Dose Adjustments

No adjustment recommended for mild renal impairment
Use with caution.

Liver Dose Adjustments

No adjustment recommended for mild to moderate hepatic impairment

Dose Adjustments

Alternative Dosing Schedules for Supervised Administration:
50 mg every weekday with 100 mg on Saturday
100 mg every other day
150 mg every third day

The degree of blockade may be reduced with these extended dosing intervals.
The risk of hepatocellular injury is higher with single doses above 50 mg.

Naloxone Challenge Test:

Intravenous: Inject 0.2 mg naloxone; observe for 30 seconds for withdrawal signs/symptoms

If no evidence of withdrawal, inject 0.6 mg naloxone; observe for an additional 20 minutes

Subcutaneous: Administer 0.8 mg naloxone; observe for 20 minutes for withdrawal signs/symptoms

Comments:

There is no completely reliable method to determine an adequate opioid free interval.
A naloxone challenge may help if there is a question of occult opioid dependence.
If signs of opioid withdrawal are observed after naloxone challenge, do not attempt naloxone treatment.
The naloxone challenge can be repeated in 24 hours.
Do not do a naloxone challenge on patients showing signs or symptoms of opioid withdrawal, or if the urine contains opioids.
A naloxone challenge can be given either intravenously or subcutaneously.
Opioid withdrawal symptoms include but are not limited to: nausea, vomiting, dysphoria, yawning, sweating, tearing, rhinorrhea, stuffy nose, craving for opioids, poor appetite, abdominal cramps, sense of fear, skin erythema, disrupted sleep patterns, fidgeting, uneasiness, poor ability to focus, mental lapses, muscle aches/cramps, pupillary dilation, piloerection, fever, changes in blood pressure, pulse or temperature, anxiety, depression, irritability, backache, bone or joint pain, tremors, sensation of skin crawling, or fasciculations.
If there is any doubt about test results, hold naltrexone and repeat challenge in 24 hours.

Precautions

The US FDA requires a Risk Evaluation and Mitigation Strategy (REMS) for Vivitrol(R). It includes a REMS document to warn patients about severe injection site reaction associated with this drug. For additional information: www.accessdata.fda.gov/scripts/cder/rems/index.cfm

CONTRAINDICATIONS:

Hypersensitivity to any of the ingredients
Patients receiving opioid analgesics
Current physiologic opioid dependence
Patients in acute opioid withdrawal
Failing a naloxone challenge or positive urine screen for opioids

Safety and efficacy have not been established in patients younger than 18 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration advice:

The intramuscular injection should be given in the gluteus, alternating buttocks for each subsequent injection.

Storage requirements:

The intramuscular injection should be refrigerated.

General:

This drug is of value only as a part of a comprehensive management plan that includes measures to ensure the patient takes this medication.

Patient advice:

Advise patients and their families that they may be more sensitive to lower opioid doses after treatment, especially at the end of a dosing interval or after a dose is missed, and are at risk of an overdose.
Attempts to overcome opioid antagonism with large doses of opioids may lead to life threatening opioid intoxication or fatal overdose.
Advise patients to bring any injection site reactions to the attention of their healthcare provider.
Inform patients of the risk of precipitated withdrawal and encourage them to give an accurate account of last opioid use.
Warn patients about the risk of hepatic injury and to seek medical attention for signs of acute hepatitis.
Alert patients and family to monitor for depression or suicidality and report symptoms to the patient's healthcare provider.
Advise patients of the risk of eosinophilic pneumonia and to seek medical attention if they develop pneumonia symptoms.
Warn patients of the risk of hypersensitivity, including anaphylaxis, and to seek immediate medical attention for anaphylaxis.