About Naltrexone®

Naltrexone® is not a narcotic. It works by blocking the effects of narcotics, especially the ``high'' feeling that makes you want to use them. It also may block the ``high'' feeling that may make you want to use alcohol. It will not produce any narcotic-like effects or cause mental or physical dependence. It will not prevent you from becoming impaired while drinking alcohol.

Naltrexone® will cause withdrawal symptoms in people who are physically dependent on narcotics. Therefore, Naltrexone® treatment is started after you are no longer dependent on narcotics. The length of time this takes may depend on which narcotic you took, the amount you took, and how long you took it. Before you start taking this medicine, be sure to tell your doctor if you think you are still having withdrawal symptoms.

Pharmacology and Mechanism of Action:
Naltrexone®, a pure opioid antagonist, is a synthetic congener of oxymorphone with no opioid agonist properties. Naltrexone® is indicated in the treatment of alcohol dependence and for the blockade of the effects of exogenously administered opioids. It markedly attenuates or completely blocks, reversibly, the subjective effects of intravenously administered opioids. When co-administered with morphine, on a chronic basis, Naltrexone® blocks the physical dependence to morphine, heroin and other opioids. In subjects physically dependent on opioids, Naltrexone® will precipitate withdrawal symptomatology.

Naltrexone® binds to the opioid mu receptor antagonistically, thereby preventing conventional opiate (heroin, morphine) drugs from binding and inducing opioid neural responses. The mechanism of action of Naltrexone® in alcoholism is not understood; however, involvement of the endogenous opioid system is suggested by preclinical data. Naltrexone® competitively binds to such receptors and may block the effects of endogenous opioids.