About Naltrexone An opioid receptor(competitive antagonists at ?- and ?- receptor) antagonist, In alcohol dependence and opioid dependence. Mechanism of Action of Naltrexone Naltrexone is a competitive opioid antagonist. It reversibly and completely blocks all the opioid receptors (mu, kappa and delta). It is an orally administered long acting, pure opioid antagonist Alcoholism: Opioid receptors are thought to be responsible for some of the reinforcing effects of alcohol. Indications for Naltrexone 1. Opioid antagonist 2. Alcoholism Interactions for Naltrexone Disulfiram: The safety and efficacy of concomitant use of naltrexone and disulfiram has not been established. Concomitant use of two potentially hepatotoxic drugs is ordinarily not recommended. Thioridazine: Lethargy and somnolence have been reported when naltrexone and thioridazine have been used. Others: Patients taking naltrexone may not benefit from opioid containing medicines like cough and cold preparations,