Which statement correctly describes morphine metabolism?

Which statement correctly describes morphine metabolism?

• A. Morphine-3-glucuronide (inactive) and morphine-6-glucuronide (ACTIVE)
• B. Morphine-3-glucuronide (ACTIVE) and morphine-6-glucuronide (inactive)
• C. Morphine-5-glucuronide and morphine-1-glucuronide
• D. Morphine is not glucuronidated

Answer: (A)

Morphine is mainly metabolized in the liver by glucuronidation, producing two major glucuronide metabolites: morphine-3-glucuronide and morphine-6-glucuronide. Morphine-3-glucuronide is pharmacologically inactive regarding analgesia (though it can cause neuroexcitation at high levels), while morphine-6-glucuronide is active and contributes to analgesia, sometimes even more potently than morphine itself. Other glucuronide forms like morphine-5-glucuronide or morphine-1-glucuronide are not clinically relevant major metabolites. So the statement that morphine-3-glucuronide is inactive and morphine-6-glucuronide is active correctly describes morphine metabolism.

Morphine is mainly metabolized in the liver by glucuronidation, producing two major glucuronide metabolites: morphine-3-glucuronide and morphine-6-glucuronide. Morphine-3-glucuronide is pharmacologically inactive regarding analgesia (though it can cause neuroexcitation at high levels), while morphine-6-glucuronide is active and contributes to analgesia, sometimes even more potently than morphine itself. Other glucuronide forms like morphine-5-glucuronide or morphine-1-glucuronide are not clinically relevant major metabolites. So the statement that morphine-3-glucuronide is inactive and morphine-6-glucuronide is active correctly describes morphine metabolism.