A drug that blocks the action of opiates (drugs used to treat pain). It may be used in the treatment of intravenous opiate addiction or alcohol dependence. Naltrexone is also being studied in the treatment of breast cancer. It may block the effects of the hormone estrogen, which causes some breast cancer cells to grow, or block the blood flow to tumors. It is a type of opiate antagonist.

A noroxymorphone derivative with competitive opioid antagonistic property. Naltrexone reverses the effects of opioid analgesics by binding to the various opioid receptors in the central nervous system, including the mu-, kappa- and gamma-opioid receptors. This leads to an inhibition of the typical actions of opioid analgesics, including analgesia, euphoria, sedation, respiratory depression, miosis, bradycardia, and physical dependence. Naltrexone is longer-acting and more potent compared to naloxone.

Derivative of noroxymorphone that is the N-cyclopropylmethyl congener of NALOXONE. It is a narcotic antagonist that is effective orally, longer lasting and more potent than naloxone, and has been proposed for the treatment of heroin addiction. The FDA has approved naltrexone for the treatment of alcohol dependence.

Synthetic congener of oxymorphone, chemically related to naloxone; a narcotic antagonist that is effective orally, longer lasting and more potent than naloxone, and has been proposed for the treatment of heroin addiction and alcohol dependence.