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Diltiazem with beta-blocker — GPhC CRA MCQ

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HardCardiovascular TherapeuticsDiltiazem with beta-blockerGPhC CRA

A patient taking bisoprolol 5 mg daily presents a new prescription for diltiazem MR 120 mg twice daily. Their resting pulse is 54 beats/min and they report intermittent dizziness. Which prescription response best addresses the immediate risk?

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Correct answer: DDefer diltiazem pending review of combined nodal blockade

Defer diltiazem pending review of combined nodal blockade: The low pulse and dizziness may already reflect clinically important rate suppression; adding a rate-limiting calcium-channel blocker to a beta blocker can precipitate symptomatic bradycardia or heart block. Supply diltiazem and check blood pressure after seven days: Blood-pressure monitoring alone would miss the immediate conduction risk suggested by the existing pulse and symptoms. Supply half-dose diltiazem pending routine clinical review: An unauthorised dose change does not resolve whether the combination is appropriate in a symptomatic bradycardic patient. Stop bisoprolol immediately and supply prescribed diltiazem: Abruptly changing established cardiac treatment without clarifying the indication and prescriber plan is unsafe. Supply both medicines with doses separated by twelve hours: Temporal separation does not remove their overlapping effects on sinus and atrioventricular-node conduction.

Reference: BNF: diltiazem hydrochloride: https://bnf.nice.org.uk/drugs/diltiazem-hydrochloride/; BNF: bisoprolol fumarate: https://bnf.nice.org.uk/drugs/bisoprolol-fumarate/