Hepatic extraction ratio — FRCA Primary MCQ

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HardPhysiologyHepatic extraction ratioFRCA Primary

For a drug with a high hepatic extraction ratio, which change is most likely to reduce systemic clearance?

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Correct answer: A — A reduction in hepatic blood flow

The best answer is “A reduction in hepatic blood flow”. For a high-extraction drug, hepatic clearance is predominantly flow limited. A fall in hepatic perfusion reduces delivery of drug to the liver and therefore lowers clearance. Changes in albumin, glomerular filtration, bile composition or erythrocyte oxygen affinity do not define this flow-limited relationship.

Reference: RCoA, Primary FRCA Syllabus: https://rcoa.ac.uk/sites/default/files/documents/2026-01/Primary-FRCA-Syllabus.pdf