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: Psychiatry
Naltrexone is used in opioid addiction because - 
Select and explain. 
A. To treat withdrawal symptoms, B. To treat overdose of opioids, C. Prevent relapse, D. Has addiction potential
C: Prevent relapse
Answer: C: Prevent relapse 
Explanation: Naltrexone can be used orally to assist in the rehabilitation of ex-opioid abusers who are fully withdrawn. However, It should be kept in mind that naltrexone should be used only after full withdrawal of opioid, otherwise acute withdrawal syndrome will be precipitated as naltrexone antagonizes the action of opioids on opioid receptors.



Naltrexone prevents relapse by discouraging substance seeking behavior → If a patient, who is on naltrexone maintenance therapy, takes on an opioid, there is no 'kicks' or 'euphoria' as opioid receptors are already blocked.