Major
Amiodarone × Azithromycin
Class III antiarrhythmics (Vaughan Williams)×Macrolides
Mechanism
Additive QT prolongation. Azithromycin received a 2013 FDA warning for fatal ventricular arrhythmia risk, particularly in patients with risk factors. Amiodarone is a potent QT-prolonging drug.
Symptoms
QT prolongation on ECG. Clinically: dizziness, syncope, palpitations. Severe cases progress to polymorphic ventricular tachycardia (torsades de pointes) with risk of ventricular fibrillation and sudden cardiac death. Risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, and ischaemic heart disease.
Management
Avoid the combination. Alternative antibiotics: doxycycline or a cephalosporin. If azithromycin is needed, ECG before start and potassium and magnesium in range.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.