Major
Dronedarone × Indapamide
Class III antiarrhythmic×Thiazide-like diuretics
Mechanism
Indapamide (thiazide-like diuretic) increases urinary potassium loss. Low potassium amplifies dronedarone's QT effect.
Symptoms
QT prolongation on ECG. Dizziness, syncope, palpitations. Severe cases: polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia and hypomagnesaemia.
Management
The combination is common (hypertension + atrial fibrillation). Check potassium and magnesium every 3 months; if potassium drops below 4.0 mmol/L, add a potassium-sparing diuretic or potassium supplement.