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PDE5 inhibitor and nitrate — GPhC CRA MCQ

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EasyCardiovascular TherapeuticsPDE5 inhibitor and nitrateGPhC CRA

A patient who uses isosorbide mononitrate asks whether sildenafil can be purchased for erectile dysfunction. Their angina is stable. What is the most important interaction to flag?

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

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Correct answer: D — Severe hypotension from combined vasodilator effect

Nitrates and phosphodiesterase-5 inhibitors can cause a marked fall in blood pressure when used together. The sale should not proceed and the patient should be referred to their prescriber. In this scenario, the correct option is severe hypotension from combined vasodilator effect. The other options are plausible but do not address the key clinical, legal or safety issue as directly. This aligns with UK pharmacy practice guidance cited in the reference field.

Reference: BNF; MEP