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Efficacy vs Potency — FRCA Primary MCQ

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HardPharmacology - General PrinciplesEfficacy vs PotencyFRCA Primary

During propofol ICU sedation, which new finding should most strongly prompt immediate consideration of stopping propofol rather than merely increasing vasopressor support?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: D — Paired metabolic acidosis and rising creatine kinase

The best answer is “Paired metabolic acidosis and rising creatine kinase”. Early propofol infusion syndrome can present with metabolic acidosis and rhabdomyolysis before catastrophic hyperkalaemia, arrhythmia or cardiac failure. Recognising the paired biochemical signal should trigger urgent reassessment and cessation or substitution. The distractors can occur during propofol use but, in isolation, do not carry the same specific implication of evolving mitochondrial and multisystem toxicity.

Reference: Propofol 1% emulsion for injection or infusion, UK SmPC: https://www.medicines.org.uk/emc/product/15152/smpc; Royal College of Anaesthetists, Primary FRCA syllabus v2.2: https://www.rcoa.ac.uk/sites/default/files/documents/2026-01/Primary-FRCA-Syllabus.pdf