NMB >90% Receptor Occupancy — FRCA Primary MCQ

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HardPharmacology - NeuromuscularNMB >90% Receptor OccupancyFRCA Primary

The mechanism by which non-depolarising agents produce neuromuscular block requires occupancy of what proportion of nicotinic receptors?

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Correct answer: D — >90%

Clinical neuromuscular block requires >90% receptor occupancy (margin of safety). Twitch depression begins at approximately 75% occupancy. This large safety margin means that considerable receptor block occurs before any clinical weakness is apparent — explaining why quantitative neuromuscular monitoring is essential.

Reference: Peck Hill Williams 2014 Pharmacology for Anaesthesia and Intensive Care