Moderate
amiodarone × furosemide
Class III antiarrhythmics (Vaughan Williams)×Loop diuretics
Mechanism
Furosemide causes hypokalemia and hypomagnesemia – increasing myocardial sensitivity to amiodarone's QT-prolonging effect. Risk of torsades de pointes.
Management
Keep potassium above 4.0 mmol/L and magnesium in the upper-normal range. Obtain an ECG with QT measurement at baseline, at 1–2 weeks, and after each amiodarone dose change.
Sources
- Lexicomp: Lexicomp Drug Interactions (2024)— Wolters Kluwer Clinical Drug Information, Inc. Lexi-Interact Online, 2024
- Pharmaceutical Press: Stockley's Drug Interactions, 12th edition (2024)— Preston CL (ed.). Stockley's Drug Interactions. 12th ed. London: Pharmaceutical Press; 2024