Major
Dronedarone × Furosemide
Class III antiarrhythmic×Loop diuretics
Mechanism
Furosemide (loop diuretic) increases urinary potassium loss. Low potassium amplifies dronedarone's QT effect, which itself carries an FDA boxed warning for this risk.
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 (atrial fibrillation + heart failure). Check potassium and magnesium every 1–3 months; if potassium drops below 4.0 mmol/L, add a potassium-sparing diuretic or potassium supplement.
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.