This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Opioids and Alcohols, Subject name: Pharmacology
[{'content': 'Which of the following drugs is a full agonist at opioid receptors, has excellent oral bioavailability, analgesic equipotency to morphine and a longer duration of action with milder withdrawal symptoms on abrupt discontinuation? \nSelect and explain. \nA. Fentanyl, B. Hydromorphone, C. Methadone, D. Nalbuphine', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Methadone is a long acting opioid agonist that has equal potency to morphine. It can be used orally for opioid replacement and opioid rotation therapy. Due to longer half life, it produces mild withdrawal symptoms.', 'role': 'assistant'}]