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Trimethoprim with ACE inhibitor — GPhC CRA MCQ

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HardCardiovascular TherapeuticsTrimethoprim with ACE inhibitorGPhC CRA

A 76-year-old patient taking ramipril and spironolactone is prescribed trimethoprim for a UTI. Their last eGFR was 38mL/min/1.73m2. What is the most important interaction to flag?

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Correct answer: CThe combination can increase the risk of hyperkalaemia

Trimethoprim can raise serum potassium, and the risk is increased with ACE inhibitors, potassium-sparing diuretics and renal impairment. This patient has several risk factors for serious hyperkalaemia. The prescription should be queried and monitoring or an alternative considered.

Reference: BNF