Final answer:
Naltrexone is a drug that acts peripherally at the mu opioid receptor and is used to block the effects of opiates.
Step-by-step explanation:
Naltrexone is a drug that acts peripherally at the mu opioid receptor. It is a narcotic antagonist that is well absorbed orally and has a long duration of action. It is commonly used in narcotic treatment programs to maintain individuals on chronic therapy with a narcotic antagonist. When taken, naltrexone blocks the effects of opiates, making them ineffective.