MajorClass III antiarrhythmics (Vaughan Williams)×Thiazide-like diuretics
Updated · Methodology
Mechanism
Indapamide (thiazide-like diuretic) increases potassium and magnesium loss. Low levels amplify amiodarone's QT-prolonging effect.
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 common (hypertension plus atrial fibrillation) but needs monitoring. Check potassium and magnesium before starting and correct any deficit. Recheck potassium within the first week after indapamide is started (per the label) and more often than usual afterwards, because amiodarone prolongs the QT interval. Monitor the ECG and QT interval. If hypokalaemia cannot be controlled, replace indapamide with a drug that does not raise the risk of torsades de pointes.
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: Amiodarone hydrochloride tablet (Dr. Reddy's Labratories Inc.) – Prescribing Information (2018)– ; DailyMed setid 95cef33b-c0e6-b17c-7cbb-f5c066872705
- FDA: Pacerone (amiodarone hydrochloride) tablets – Prescribing Information (2025)– FDA, DailyMed SPL, Upsher-Smith Laboratories, раздел 7
- AEMPS: Ficha técnica Trangorex 200 mg comprimidos (amiodarona) (2022)– AEMPS, CIMA, nº registro 48048, revisión 01/2022, sección 4.5
- AEMPS: Ficha técnica Tertensif 2,5 mg comprimidos recubiertos con película (indapamida) (2022)– AEMPS, CIMA, nº registro 53338, revisión 06/2022, secciones 4.4 y 4.5