Major
Dronedarone × Mirtazapine
Class III antiarrhythmic×Other antidepressants (NaSSA)
Mechanism
Mirtazapine prolongs QT dose-dependently (especially above 30 mg/day). Combined with dronedarone, torsades de pointes risk rises.
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 acceptable at low mirtazapine doses (≤30 mg/day) and normal potassium. ECG before start and at 2 weeks. Alternative antidepressants with minimal QT effect: agomelatine or sertraline (up to 100 mg).
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.