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
Which of the following statements about opioid receptor antagonists is false - 
Select and explain. 
A. Naloxone can be used for treatment of opioid induced constipation, B. Naltrexone may be used for treatment of alcohol dependence, C. Nalmefine has a longer half life than naloxone, D. Naloxone is more potent than naltrexone
D: Naloxone is more potent than naltrexone
Answer: D: Naloxone is more potent than naltrexone 
Explanation: Ans. is 'd' i.e., Naloxone is more potent than naltrexone o Naltrexone is more potent than naloxone. Naltrexone has 3 to 5 times more potency than naloxone. o Opioid induced constipation that is refractory to laxative may be treated with oral naloxone. Oral naloxone can reverse opioid induced constipation without precipitating withdrawal because of its extensive hepatic first pass metabolism, which leads to low plasma level. o Naltrexone is used to decrease craving in chronic alcoholism.