Pharmacology · Class
Cardiac glycosides !
Plant-derived medicines (from foxglove) that make the heart contract a little stronger and slow conduction through the AV node.
Updated 2026-11-01
What they are
Inhibitors of the sodium-potassium pump (Na⁺/K⁺-ATPase), originally from the foxglove plant (Digitalis). Today they are used for symptom control in heart failure and to slow the heart rate in atrial fibrillation.
Mechanism of action
Blocking the sodium pump raises sodium inside the heart cell, so the sodium-calcium exchanger removes less calcium. More calcium is stored and released with each beat, which strengthens contraction. They also increase vagal tone, slowing the sinus node and AV conduction.
Target: Na⁺/K⁺-ATPase (sodium-potassium pump)
Drugs in this class
Others in the class
- Digitoxin
Test yourself
Think of the answer, then tap the question to see it.
How does inhibiting the Na⁺/K⁺-ATPase increase myocardial contractility?
Intracellular sodium rises, the sodium-calcium exchanger removes less calcium, the sarcoplasmic reticulum stores more calcium and releases more with each beat.
Why does hypokalaemia increase the risk of digoxin toxicity?
Potassium and digoxin compete for the same binding site on the pump; with less potassium, more digoxin binds and the effect is stronger.
What is the specific treatment for severe digoxin toxicity?
Digoxin-specific antibody fragments (Fab), which bind the drug and remove it from its target.
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Digoxin: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2017); eEML - Electronic Essential Medicines List (World Health Organization, 2025); DailyMed - DIGOXIN tablet (DailyMed (U.S. National Library of Medicine), 2026).
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Representative model, for educational purposes only.