Propofol Vd Steady State — FRCA Primary MCQ

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HardPharmacology - Intravenous AnaestheticsPropofol Vd Steady StateFRCA Primary

In a 70-kg adult, which of the following is the closest approximation to propofol's apparent volume of distribution at steady state, rather than its central volume of distribution?

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Correct answer: C — 200–300 L

The correct answer is C. Propofol has a steady-state volume of distribution of approximately 1.8–5.3 L/kg. In a 70-kg adult, this corresponds to about 126–371 L, so 200–300 L is the closest option. Its large apparent volume reflects extensive distribution into peripheral tissues, consistent with high lipid solubility. This must be distinguished from the much smaller central volume of distribution, reported as 0.2–0.79 L/kg; 20 L is therefore a plausible central-compartment value but not the steady-state value. Four litres approximates plasma volume, while 60 L remains too small for propofol's steady-state distribution. Values around 1000 L may arise from terminal-phase or model-dependent apparent distribution estimates but do not represent the SmPC steady-state volume.

Reference: B. Braun Medical. Propofol 1% (10 mg/ml) emulsion for injection or infusion, Summary of Product Characteristics, section 5.2 Pharmacokinetic properties. Revised 26 August 2024. https://www.medicines.org.uk/emc/product/15152/smpc