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Trimethoprim and renal hyperkalaemia — GPhC CRA MCQ

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HardRenal and Hepatic ImpairmentTrimethoprim and renal hyperkalaemiaGPhC CRA

A 77-year-old man with CKD stage 3 takes ramipril and spironolactone. He is prescribed trimethoprim for UTI. What is the most important interaction to flag?

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Correct answer: D — Trimethoprim can increase hyperkalaemia risk

Trimethoprim can increase potassium, and risk is higher with ACE inhibitors, potassium-sparing diuretics and CKD. Hyperkalaemia can be serious and requires prescriber review and monitoring. Alternative antibiotics may be preferable depending on culture and renal function.

Reference: BNF