Digoxin
A plant-derived cardiac glycoside that strengthens contraction and slows AV conduction, for heart failure and rate control in atrial fibrillation.
Drug card
- Class
- Cardiac glycoside
- How it works
- Inhibiting the sodium pump, so heart cells gain calcium and contract harder
- Used for
- Mild to moderate heart failure
- Rate control in chronic atrial fibrillation
- Heart failure in children, to strengthen contraction
- Known for
- Nausea and vomiting, early signs of toxicity
- Yellow-green vision, halos or blurring
- Almost any arrhythmia, including ventricular tachycardia
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does digoxin work?
Inhibits the Na+/K+-ATPase, raising the calcium available to heart muscle so contraction strengthens, and acts through the vagus to slow the sinus node and AV conduction. In heart failure it eases symptoms and cuts hospital admissions but does not lower mortality. The kidneys clear most of it, and its therapeutic index is narrow.
Uses
What is digoxin used for?
- Mild to moderate heart failure
- Rate control in chronic atrial fibrillation
- Heart failure in children, to strengthen contraction
Side effects
Side effects of digoxin
- Nausea and vomiting, early signs of toxicityKnown for
- Yellow-green vision, halos or blurringKnown for
- Almost any arrhythmia, including ventricular tachycardiaKnown forSerious
- Loss of appetite
- Heart block, up to complete blockSerious
- Slow heart rate
- Confusion, delirium or hallucinations
- Diarrhea
- Tiredness and weakness
- Dizziness and headache
- Breast enlargement with long-term use
- High potassium in severe overdoseSerious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Contraindicated in ventricular fibrillation; with Wolff-Parkinson-White and atrial fibrillation it can trigger VF.
- Low potassium or magnesium, often from diuretics, makes toxicity likely even at therapeutic levels.
- Kidney impairment raises levels and prolongs toxicity, so smaller maintenance doses are used.
- Amiodarone, clarithromycin, erythromycin, itraconazole, quinidine and verapamil raise digoxin levels.
Good to know: Toxicity can mimic worsening heart failure; digoxin immune Fab, an antibody fragment, binds the drug in severe poisoning.
Remember it
A way to remember it
Too much digoxin: a sick stomach, yellow vision and an irregular beat.
Nausea, vomiting and poor appetite usually come first; vision turns yellow-green or shows halos; and almost any arrhythmia or heart block can follow, more readily when potassium is low.
Written for biofideX
Its class
Cardiac glycosides
They inhibit the Na+/K+-ATPase, the sodium pump of heart muscle cells. With sodium held inside the cell, more calcium becomes available to the contractile proteins and each beat is stronger. They also raise vagal tone, slowing the sinus rate and conduction through the AV node, which controls the ventricular rate in atrial fibrillation.
Easily mixed up with class III antiarrhythmics, beta blockers and non-dihydropyridine calcium channel blockers.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Heart failure, rhythm and angina
Digoxin is one of 10 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
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