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Ivabradine and diltiazem — GPhC CRA MCQ

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HardCardiovascular TherapeuticsIvabradine and diltiazemGPhC CRA

A 60-year-old man with stable angina takes ivabradine 5 mg twice daily. A new prescription for diltiazem modified-release 120 mg daily is presented for rate control. His resting pulse is 56 bpm. What is the most important interaction to flag?

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Correct answer: A — Flag the combination because diltiazem can increase ivabradine exposure and bradycardia risk

Diltiazem is a moderate CYP3A4 inhibitor and can increase ivabradine exposure, with additive heart-rate lowering. Existing bradycardia makes this more clinically important. The prescription should be queried before supply.

Reference: BNF