Naltrexone is used to maintain abstinence following opioid withdrawal in addicts. It blocks all of the following features of opioid use, except.

Ans. (B) Craving for opioids(Ref: Goodman and Gilman 12th/661)Naltrexone has no action in the absence of agonists but promptly reverses the opioid effects when administered i.v.It can reverse all effects of opioids like sedation, analgesia, constipation, respiratory depression and miosis etc but it do not reduce craving.