Morphine-6-glucuronide (M6G) is an active metabolite of morphine that contributes significantly to analgesia. Which statement about M6G is correct?

• A M6G is pharmacologically inactive and only serves as an excretion pathway for morphine
• B M6G is a neurotoxic metabolite causing myoclonus and seizures
• C M6G is formed by CYP2D6 metabolism and is responsible for codeine activation
• D M6G is an active analgesic metabolite that accumulates in renal failure, prolonging opioid effects ✓

Explanation

Morphine-6-glucuronide is a potent active metabolite with analgesic activity, formed by UGT2D7 glucuronidation. It accumulates in renal failure because it is renally excreted, causing prolonged and potentially dangerous opioid effects. Morphine-3-glucuronide, the other major metabolite, is not analgesic and may contribute to neuroexcitation. This is why morphine requires caution in kidney disease.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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