Amiodarone × Bisoprolol

Both drugs slow the heart rate and cardiac conduction. Bisoprolol is a selective beta-blocker (bisoprolol SmPC). Amiodarone blocks alpha and beta adrenoceptors non-competitively and slows conduction through the sinus and atrioventricular nodes (amiodarone SmPC). Together they increase bradycardia and conduction disorders (both SmPCs). Amiodarone is eliminated over months, so the interaction can persist for several months after it is stopped (amiodarone SmPC).

Marked bradycardia, dizziness, weakness, fainting. On the ECG: atrioventricular block of varying degree, sinoatrial block, and rarely sinus arrest. In older patients the heart rate can fall especially sharply (amiodarone SmPC).

The amiodarone SmPC does not recommend combining it with beta-blockers because of the risk of marked bradycardia and conduction disorders. The bisoprolol SmPC lists the combination with amiodarone as one to use with caution. If a cardiologist still prescribes both, monitor the heart rate (US Food and Drug Administration (FDA) amiodarone label). Before amiodarone is started, record an ECG and check serum potassium (amiodarone SmPC). Stop amiodarone if second- or third-degree atrioventricular block, sinoatrial block or bifascicular block develops (amiodarone SmPC). In older patients the heart rate can fall especially sharply. The interaction can persist for several months after amiodarone is stopped, so keep checking the heart rate after that too (amiodarone SmPC).