Which statement about naltrexone is NOT true?

Which statement about naltrexone is NOT true?

• A. It has receptor binding properties similar to naloxone.
• B. It blocks euphoric effects of opioids.
• C. It is a full mu agonist with intrinsic activity.
• D. It has extended-release formulations used for alcohol withdrawal programs.

Answer: (C)

Naltrexone is an opioid receptor antagonist with high affinity for mu receptors and no intrinsic activity. It binds but does not activate the receptor, so it blocks opioid effects rather than producing opioid effects. That’s why describing it as a full mu agonist with intrinsic activity is not true. It behaves similarly to naloxone in that both are pure antagonists at mu receptors and block the euphoric effects of opioids. There are extended-release formulations used in alcohol dependence treatment programs to support relapse prevention, not for acute withdrawal.

Naltrexone is an opioid receptor antagonist with high affinity for mu receptors and no intrinsic activity. It binds but does not activate the receptor, so it blocks opioid effects rather than producing opioid effects. That’s why describing it as a full mu agonist with intrinsic activity is not true. It behaves similarly to naloxone in that both are pure antagonists at mu receptors and block the euphoric effects of opioids. There are extended-release formulations used in alcohol dependence treatment programs to support relapse prevention, not for acute withdrawal.