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Nitrate tolerance counselling — GPhC CRA MCQ

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ModerateCardiovascular TherapeuticsNitrate tolerance counsellingGPhC CRA

A 59-year-old man is prescribed isosorbide mononitrate MR 60mg daily for angina. He asks why the directions say once daily in the morning rather than twice daily. What would you advise the patient?

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

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Correct answer: B — A nitrate-low period helps reduce tolerance and maintain effect

Long-acting nitrates are usually dosed to provide a nitrate-low interval, reducing tolerance and preserving antianginal effect. Morning dosing may also match daytime exertional symptoms for many patients. This is a pharmacological tolerance issue, not allergy or legal classification. Grapefruit juice is not required for nitrate absorption.

Reference: BNF; NICE CKS Angina