Major
Amiodarone × Mirtazapine
Class III antiarrhythmics (Vaughan Williams)×Other antidepressants (NaSSA)
Mechanism
Mirtazapine prolongs QT dose-dependently. Combined with amiodarone, torsades de pointes risk rises, especially in older patients and with hypokalaemia.
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
The combination is acceptable at low mirtazapine doses (≤30 mg/day) and normal potassium. ECG before start and at 2 weeks. Alternative antidepressant with minimal QT effect: agomelatine.
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.