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NMBA Choice Renal Failure — FRCA Final MCQ

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ModerateGeneral AnaesthesiaNMBA Choice Renal FailureFRCA Final

A 70-year-old man (ASA III) with CKD stage 4 (eGFR 18) requires anaesthesia for an urgent below-knee amputation. Regarding choice of non-depolarising neuromuscular blocking agent, which has the LEAST dependence on renal elimination?

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Correct answer: DCisatracurium

Cisatracurium is the non-depolarising agent with the least renal dependence. It undergoes organ-independent elimination via Hofmann degradation (spontaneous chemical breakdown at physiological pH and temperature), the same mechanism as atracurium but with greater stereochemical specificity. This makes its duration predictable regardless of renal or hepatic function. Pancuronium (40% renal excretion), vecuronium (15-25% renal, predominantly hepatic), and rocuronium (primarily hepatic but some renal) all have prolonged duration in severe renal impairment.

Reference: RCOA – 2023 – Pharmacology of muscle relaxants; BNF – 2025 – Cisatracurium