Naltrexone Uses

Naltrexone is used to treat alcohol and drug abuse. It helps people with alcohol dependence by decreasing alcohol cravings. In addition, naltrexone blocks the effects of opioid drugs (both prescription opioid medications with abuse and diversion potential as well as opioid-containing illicit drugs like heroin). Naltrexone is prescribed as part of a comprehensive substance abuse treatment plan, along with counseling and social support.

Note that naltrexone should not be used to treat addiction in people who are currently using or have a physical dependence on alcohol, opioid-containing medicines, or opioid street drugs. Your addiction medicine specialist will only prescribe medications such as naltrexone after you have been opioid-free for 7-14 days. To test for physical dependence, your doctor may give you a naloxone challenge test. This involves the injection of a drug called naloxone. If the test causes withdrawal symptoms, you should not start naltrexone. Your provider may do a repeat naloxone challenge test to confirm whether you can safely start naltrexone.

There may be other uses for naltrexone—your doctor or pharmacist can give you further drug information.

Naltrexone Mechanism of Action

Naltrexone binds to the mu opioid receptor (and to a lesser extent to delta and kappa opioid receptors). Because naltrexone blocks opioid receptors, it prevents the binding of opioid-containing medicines to these receptors, thereby reducing opioid cravings. 

The mechanism of action of naltrexone in reducing alcohol consumption is not completely understood. It is believed that naltrexone reduces alcohol cravings by blocking the effects of endogenous opioids.

Naltrexone Doses

Oral naltrexone hydrochloride comes in the form of a 50-mg tablet to take by mouth.

Extended release injectable naltrexone (Vivitrol) must be prepared and administered by a healthcare provider and given by intramuscular injection every 4 weeks.

Subcutaneous naltrexone implants can be placed under the skin by a healthcare provider every 10-12 weeks.