Hepatic Effects
• Possible dose-related hepatotoxicity. Margin between therapeutic and hepatotoxic dosages may be less than fivefold; hepatotoxicity not apparent at usual dosages. (See Hepatic Effects under Cautions.)
• Contraindicated in patients with acute hepatitis or liver failure; carefully weigh potential benefits against possible hepatotoxic risks in patients with active liver disease.
• Instruct patients to discontinue naltrexone and contact a clinician if manifestations of acute hepatitis occur. (See Advice to Patients.)

REMS:

FDA approved a REMS for naltrexone to ensure that the benefits of a drug outweigh the risks. The REMS may apply to one or more preparations of naltrexone and consists of the following: medication guide and communication plan. See the FDA REMS page ([Web]) or the ASHP REMS Resource Center ([Web]).