amiodarone and bisoprolol

MajorAvoid this combination where possible.

Mechanism

Additive pharmacodynamic effects on cardiac conduction and heart rate (bradycardia, AV block, hypotension). Amiodarone also inhibits CYP2D6 and CYP3A4, potentially reducing bisoprolol clearance and increasing its plasma concentration.

What it means clinically

Concomitant use can result in symptomatic bradycardia, heart block, or hypotension, particularly in patients with pre-existing conduction abnormalities or impaired ventricular function. The risk is increased when amiodarone is initiated in a patient already taking bisoprolol.

What to do

Monitor heart rate and blood pressure closely, especially after starting amiodarone. Consider reducing the bisoprolol dose or avoiding the combination in patients with bradycardia, heart block, or heart failure. Adjust doses based on clinical response and ECG findings.

Evidence

Well-established interaction; combination is occasionally used intentionally in atrial fibrillation with rate control, but requires careful monitoring. Pharmacokinetic component supported by studies showing amiodarone increases bisoprolol concentrations.

The two drugs

amiodaroneClass III antiarrhythmicRead the monograph bisoprololBeta-adrenergic blockersRead the monograph

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Other interactions involving amiodarone or bisoprolol

Educational reference for students and clinicians in training. It does not replace professional judgement, local protocols or current prescribing information.