CriticalClass III antiarrhythmics (Vaughan Williams)×Selective serotonin reuptake inhibitors (SSRIs)
Updated · Methodology
Mechanism
Amiodarone is a class III antiarrhythmic, and its SmPC describes QT prolongation as a direct pharmacological effect of the drug. Class IA and III antiarrhythmics open the list of examples in both SSRI labels. The escitalopram SmPC contraindicates any QT-prolonging drug alongside it: the ban is written broadly, and the classes in brackets are examples.
Symptoms
QTc prolongation on ECG, palpitations, dizziness, syncope. The end point is polymorphic ventricular tachycardia of the torsade type progressing to ventricular fibrillation. The risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, decompensated heart failure and in women.
Management
The pair sits in the escitalopram SmPC contraindications, so the question is which drug stays, not how far to cut the dose. Amiodarone washes out over weeks, so spacing the two drugs apart does not work: QT stays prolonged long after the last dose. Before any decision, potassium and magnesium are corrected and an ECG with QTc is recorded.
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.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- FDA: Lexapro (escitalopram) prescribing information (2023)– FDA label, Allergan, Inc., DailyMed setid 13bb8267-1cab-43e5-acae-55a4d957630a, revised 10/2023, sections 4, 5.2 and 7
- AEMPS: Ficha técnica de Trangorex 200 mg (amiodarona) (2022)– AEMPS CIMA, nregistro 48048, revisión 08/2022, secciones 4.4 y 4.5
- AEMPS: Ficha técnica de Cipralex 10 mg (escitalopram) (2026)– AEMPS CIMA, nregistro 65230, revisión 03/2026, secciones 4.3 y 4.5