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Trimethoprim and hyperkalaemia — GPhC CRA MCQ

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HardRenal and Hepatic ImpairmentTrimethoprim and hyperkalaemiaGPhC CRA

A 72-year-old with a stable eGFR of 24 mL/min is prescribed a seven-day course of trimethoprim using the usual adult dose. Which renal schedule is stated in the current SmPC?

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

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Correct answer: C — Use the normal dose for three days, then halve it

The current trimethoprim SmPC gives a specific renal schedule. For eGFR 15–30 mL/min, use the normal dose for the first three days and then half the normal dose. Below 15 mL/min it gives half the normal dose rather than an automatic prohibition, although dialysis initiation requires specialist supervision. Renal function and electrolytes should be considered for monitoring, particularly with longer treatment.

Reference: Trimethoprim SmPC: https://www.medicines.org.uk/emc/product/4566/smpc