Brands, Medical Use, Clinical Data
- Anti-craving Agents
- Alcohol Antagonists
- Opiate Antagonists
- Tablet (scored, film-coated, 50 mg)
Brands / Synonyms
Celupan; Embeda; N-Cyclopropylmethylnoroxymorphone; Naltrexona [Inn-Spanish]; Naltrexone; Naltrexone Hcl; Naltrexone [Usan:Ban:Inn]; Naltrexonum [Inn-Latin]; ReVia; Vivitrex
For use in the treatment of alcohol dependence and for the blockade of the effects of exogenously administered opioids.
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.
Mechanism of Action
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.
Although well absorbed orally, naltrexone is subject to significant first pass metabolism with oral bioavailability estimates ranging from 5 to 40%.
In the mouse, rat and guinea pig, the oral LD50s were 1,100-1,550 mg/kg; 1,450 mg/kg; and 1,490 mg/kg; respectively. High doses of naltrexone (generally ≥1,000 mg/kg) produce salivation, depression/reduced activity, tremors, and convulsions.
Biotrnasformation / Drug Metabolism
Hepatic. When administered orally, naltrexone undergoes extensive biotransformation and is metabolized to 6 beta-naltrexol (which may contribute to the therapeutic effect) and other minor metabolites.
REVIA is contraindicated in:
- Patients receiving opioid analgesics.
- Patients currently dependent on opioids.
- Patients in acute opioid withdrawal.
- Any individual who has failed the naloxone challenge test or who has a positive urine screen for opioids.
- Any individual with a history of sensitivity to REVIA or any other components of this product. It is not known
if there is any cross-sensitivity with naloxone or the phenanthrene containing opioids.
- Any individual with acute hepatitis or liver failure.
Studies to evaluate possible interactions between REVIA and drugs other than opiates have not been performed.
Consequently, caution is advised if the concomitant administration of REVIA and other drugs is required.
The safety and efficacy of concomitant use of REVIA and disulfiram is unknown, and the concomitant use of two
potentially hepatotoxic medications is not ordinarily recommended unless the probable benefits outweigh the known
Lethargy and somnolence have been reported following doses of REVIA and thioridazine.
Patients taking REVIA may not benefit from opioid containing medicines, such as cough and cold preparations,
antidiarrheal preparations, and opioid analgesics. In an emergency situation when opioid analgesia must be
administered to a patient receiving REVIA, the amount of opioid required may be greater than usual, and the resulting
respiratory depression may be deeper and more prolonged.