Norpethidine Seizures — FRCA Primary MCQ
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Correct answer: E — Has an active metabolite norpethidine that can cause seizures especially in renal failure
Norpethidine (normeperidine) is an active metabolite with approximately half the analgesic potency of pethidine but significant neurotoxic properties. It accumulates in renal failure and with prolonged use causing tremor / myoclonus / and seizures. Pethidine also has mild anticholinergic properties (tachycardia / mydriasis) and serotonergic effects.
Reference: Peck Hill Williams 2014 Pharmacology for Anaesthesia and Intensive Care