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Trimethoprim hyperkalaemia — GPhC CRA MCQ

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HardInfectionsTrimethoprim hyperkalaemiaGPhC CRA

A 72-year-old woman is prescribed trimethoprim for UTI. She takes spironolactone 25mg daily and ramipril 10mg daily. Her latest potassium is 5.1mmol/L and eGFR is 39mL/min/1.73m2. What is the most appropriate action?

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Correct answer: E — Contact the prescriber because severe hyperkalaemia risk is increased

Trimethoprim can increase serum potassium, and risk is greater with potassium-sparing diuretics, ACE inhibitors, renal impairment and elevated baseline potassium. This patient's combination is high risk and should be reviewed before supply. Dietary potassium advice would worsen risk. The pharmacist should not independently stop ramipril permanently or substitute antibiotics.

Reference: BNF