Known brand names include Lanoxin and Digox.
A cardiac glycoside that makes the heart pump more strongly and slows the heart rate. It treats mild to moderate heart failure and controls the heart rate in chronic atrial fibrillation. The gap between helpful and toxic levels is narrow.
Labeled use. Control of resting ventricular rate in chronic atrial fibrillation; does not slow the rate much during exercise.
Labeled use. Mild to moderate heart failure in adults; improves symptoms and hospitalizations, not survival. Also increases contractility in children.
Not first line. Add digoxin in heart failure with reduced ejection fraction when symptoms persist on guideline therapy, since it reduces hospitalizations but not mortality. For atrial fibrillation rate control, beta blockers or nondihydropyridine calcium channel blockers come first; digoxin helps with coexisting heart failure or low blood pressure but does not control rate during exercise. Avoid in WPW.
Inhibits the sodium-potassium ATPase pump, which raises calcium inside heart cells and strengthens contraction. It also boosts vagal tone, which slows the sinus rate and AV node conduction. Oral onset is 0.5 to 2 hours, with peak effect in 2 to 6 hours; half-life is 1.5 to 2 days with normal kidneys.
Narrow therapeutic index. The label states that digoxin has a narrow therapeutic index. Serum levels below 0.5 ng/mL are linked to reduced efficacy and levels above 2 ng/mL to toxicity.
Doses come from the FDA label. Study tool, not for clinical decisions.
Required. Digoxin is mainly cleared by the kidneys, so lower maintenance doses are needed as creatinine clearance falls (see the label's dose tables). Half-life lengthens, steady state takes longer, and toxicity lasts longer. It is prolonged to 3.5 to 5 days in anuria.
None on the current Lanoxin label. Digoxin toxicity is a labeled warning instead.
Sources: [1]
Sources: [1]
Digoxin immune Fab (DigiFab) for life-threatening arrhythmias, high-grade AV block, or hyperkalemia; it is 80% to 90% effective. Stop digoxin and place on a cardiac monitor. Correct low potassium (keep 4.0 to 5.5 mmol/L) and magnesium, but avoid potassium with bradycardia or heart block. Atropine or pacing for bradycardia. Give activated charcoal after a large ingestion. Dialysis does not remove digoxin.
Sources: [1]
Decades of use have not shown a clear link to birth defects or miscarriage. Digoxin crosses the placenta, so watch the newborn for toxicity. Dose needs may rise during pregnancy and fall after delivery; monitor levels.
Sources: [1]
The infant gets up to 4% of a neonatal maintenance dose through milk, which is unlikely to matter clinically.
Sources: [1]
Increases contractility in children with heart failure, but safety is not established in controlled studies and rate control in pediatric atrial fibrillation is not established. Ages 5 to 10: total load 20 to 45 mcg/kg; maintenance 3.2 to 6.4 mcg/kg per dose twice daily. Infants and premature newborns are very sensitive; use the oral solution. Any new arrhythmia in a child should be presumed digoxin toxicity.
Most experience is in older adults, with no difference in response. Because kidney function declines with age, base the dose on renal function and watch closely for toxicity.
Sources: [1]