Major
Amiodarone × Propranolol
Class III antiarrhythmics (Vaughan Williams)×Non-selective beta blocker
Mechanism
Additive bradycardia and AV conduction suppression. Propranolol is non-selective, with higher risk than bisoprolol (affects β2 receptors, potentially causing bronchospasm in asthma).
Symptoms
Bradycardia (heart rate below 50/min), dizziness, syncope. ECG: first- to second-degree AV block. Older patients: fall risk.
Management
The combination is appropriate in cardiology. Reduce propranolol by 25–50% when starting amiodarone. Check pulse and ECG at 1 and 4 weeks. In asthma or COPD, a selective beta-blocker (bisoprolol) is preferred.