digoxin and carvedilol

ModerateUsually manageable, but it must be recognised and monitored.

Mechanism

Carvedilol inhibits P-glycoprotein-mediated renal and biliary efflux of digoxin, increasing digoxin plasma concentrations. Additionally, both drugs have additive negative chronotropic and dromotropic effects on the sinoatrial and atrioventricular nodes.

What it means clinically

Increased digoxin levels may precipitate digoxin toxicity (e.g., nausea, vomiting, visual disturbances, cardiac arrhythmias). Combined bradycardic effects can lead to symptomatic bradycardia or heart block, particularly in patients with underlying conduction disease.

What to do

Monitor serum digoxin concentrations and electrocardiogram (heart rate and PR interval) after initiation or dose changes of carvedilol. Adjust the digoxin dose as needed. Advise patients to report symptoms of toxicity or bradycardia.

Evidence

Well-established interaction; supported by pharmacokinetic studies and clinical observation. P-glycoprotein inhibition by carvedilol is documented.

The two drugs

digoxinCardiac glycosidesRead the monograph carvedilolBeta-adrenergic blockersRead the monograph

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Other interactions involving digoxin or carvedilol

Educational reference for students and clinicians in training. It does not replace professional judgement, local protocols or current prescribing information.