This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
Naltrexone is used to maintain abstinence following opioid withdrawal in addicts. It blocks all of the following featues of opioid use, except - 
Select and explain. 
A. Euphoriant effects of opioids, B. Craving for opioids, C. Miosis, D. Respiratory depression
B: Craving for opioids
Answer: B: Craving for opioids 
Explanation: Ans. is 'b' i.e., Craving for opioids o Naltrexone can reverse all effects of opioids like sedation, analgesia, constipation, respiratory depression and miosis, but it does not reduce craving. "Craving for opioids may continue during naltrexone treatment" Principles of addiction medicine o It is interesting to know that naltrexone does not reduce craving for opioid, but it reduces craving for alcohol in chronic alcoholism