A 55-year-old patient with chronic kidney disease on meperidine (pethidine) for pain develops confusion, myoclonus, and a generalized tonic-clonic seizure. The cause is accumulation of which metabolite?

• A Normeperidine ✓
• B Morphine-6-glucuronide
• C Hydromorphone-3-glucuronide
• D Noroxymorphone

Explanation

Meperidine is metabolized in the liver to normeperidine, a neurotoxic metabolite with a longer half-life than the parent drug. Normeperidine accumulates in renal impairment and causes CNS excitation manifesting as myoclonus, agitation, and seizures. It is not reversed by naloxone. Meperidine is therefore contraindicated in renal failure and for chronic pain management.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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