CriticalCardiac glycosides (digitalis)×Class Ia antiarrhythmic (sodium channel blocker with intermediate kinetics)
Updated · Methodology
Mechanism
Quinidine inhibits renal and intestinal P-glycoprotein – digoxin clearance drops 50%. Concentration doubles with digoxin toxicity risk (bradycardia, AV block, ventricular arrhythmias).
Symptoms
Nausea, vomiting, visual disturbances, bradycardia, AV block within 5–7 days.
Management
Reduce digoxin by 50% when starting quinidine. Check level on day 5.
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
- DailyMed: Quinidine: FDA prescribing information, Drug Interactions section (DailyMed) (2024)
- AEMPS: Ficha técnica: Digoxina (nº registro 34753), sección 4.5 (2026)– AEMPS, CIMA, nº registro 34753, revisión 02/2026, sección 4.5