Major
Dronedarone × Quetiapine
Class III antiarrhythmic×Atypical antipsychotics
Mechanism
Additive QT prolongation (both prolong QTc). Dronedarone carries an FDA boxed warning for QT 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
Avoid the combination. Alternative antipsychotics with minimal QT effect: olanzapine or aripiprazole. Alternative antiarrhythmic: a beta-blocker for rate control or catheter ablation.
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.