Antagonist Maintenance - Opioid Use Disorders

Antagonist Maintenance

Naltrexone is the prototypical opioid antagonist used in absti-nence therapy, blocking the effects of heroin and other opioids through competitive receptor inhibition. Naltrexone has no opioid agonist effects and is a competitive opioid antagonist. It is orally effective and can block opioid effects for 24 hours when admin-istered as a single daily dose of 50 mg; doses of 100 to 150 mg can block opioid effects for 48 to 72 hours. Despite a favorable adverse event profile (nausea is typically the most common side effect), naltrexone is generally not favored by opioid addicts be-cause, unlike opioid agonists and partial agonists, it produces no positive, reinforcing effects. Furthermore, it may be associated with the precipitation of an opioid withdrawal syndrome if used too soon after opioid use stops, an effect that can be minimized by administering a naloxone challenge prior to giving the first dose of naltrexone.