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Naltrexone Dosage

Medically reviewed on August 28, 2017.

Applies to the following strengths: 50 mg; 380 mg

Usual Adult Dose for Alcohol Dependence

Oral Tablets:
50 mg orally once a day

Extended-release injectable suspension:
380 mg every 4 weeks (or once a month) via intramuscular gluteal injection, alternating buttocks

Usual Adult Dose for Opiate Dependence

Treatment should not be attempted unless the patient has remained free of opioids for at least 7 to 10 days. Opioid abstinence should be verified by analysis of urine for absence of opioids. The patient should not be manifesting withdrawal signs or reporting withdrawal symptoms. If there is any question of occult opioid dependence, perform a naloxone challenge test and do not initiate naltrexone therapy until the naloxone challenge is negative. The naloxone challenge test should not be performed in a patient showing clinical signs or symptoms of opioid withdrawal, or whose urine contains opioids. The naloxone challenge can be repeated in 24 hours.

Initial dose: 25 mg orally one time.
Maintenance dose: If no withdrawal signs occur, 50 mg orally once a day may be started.
Alternative dose schedules: (to improve compliance) 50 mg orally on week days and 100 mg orally on Saturday; or 100 mg orally every other day; or 150 mg orally every third day.

Extended-release injectable suspension: 380 mg every 4 weeks (or once a month) via intramuscular gluteal injection, alternating buttocks

Renal Dose Adjustments

Urinary excretion is the primary route of elimination for the active metabolites of naltrexone. Data are lacking concerning the safety and disposition of oral naltrexone in patients with renal dysfunction, and there are no data on the recommended oral dose of naltrexone in patients with renal dysfunction.

No dosage adjustment is required in patients with mild renal dysfunction (CrCl 50 to 80 mL/min) who are receiving the extended-release injectable suspension. However, there are no data on the pharmacokinetic disposition of injectable naltrexone in patients with moderate to severe renal dysfunction (CrCl less than 50 mL/min).

Liver Dose Adjustments

Naltrexone undergoes extensive hepatic metabolism and has the potential to cause further hepatic injury in patients with liver dysfunction. Therefore, the use of naltrexone is not recommended in patients with acute hepatitis or liver failure and should be used with caution in patients with active liver disease.

No dosage adjustment is required in patients with mild or moderate liver dysfunction who are receiving the extended-release suspension.


Naltrexone may cause hepatic injury when taken in excess or by people who develop liver disease from other causes. Patients that develop abdominal pain lasting more than a few days, white bowel movements, dark urine, or yellowing of the eyes, should stop taking naltrexone immediately and see a doctor as soon as possible. There may be a higher risk of hepatocellular injury with single doses greater than 50 mg, and use of higher doses and extended dosing intervals should balance the possible risks against the probable benefits.

Safety and effectiveness have not been established in pediatric patients (less than 18 years of age).


Data not available

Other Comments

The US FDA requires a Risk Evaluation and Mitigation Strategy (REMS) for naltrexone extended-release injectable. This includes a medication guide. Additional information is available at

Naltrexone should be considered as only one of many factors determining the success of treatment of alcoholism. Factors associated with a good outcome in clinical trials were the type, intensity, and duration of treatment, appropriate management of comorbid conditions, use of community based support groups, and good medication compliance. To achieve the best possible treatment outcome, appropriate compliance- enhancing techniques should be implemented for all components of the treatment program, especially medication compliance.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.