system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Which of the following drugs is a full agonist at opioid receptors, has excellent oral bioavailability, analgesic equipotency to morphine and a longer durationlof action with milder withdrawal symptoms on abrupt discontinuation?
assistant
The correct answer is  (Ref: KDT 6/e p459, 460) 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.