Digitoxin is the cardiac glycoside derived from Digitalis purpurea and used to treat certain heart conditions.
Digitalis purpurea, commonly known as foxglove, contains potent cardiac glycosides, especially digitoxin. At carefully controlled doses, digitoxin can strengthen the force of heart contraction and help regulate certain abnormal rhythms. It has been used in managing heart failure and some arrhythmias, although modern treatment often favors medicines with wider safety margins.
The compound works by inhibiting the sodium–potassium ATPase pump in heart cells. This changes intracellular sodium and calcium levels, increasing the calcium available for contraction while also slowing conduction through the atrioventricular node. Because the difference between a therapeutic and toxic dose is small, digitoxin requires medical supervision.
The most common mix-up is with digoxin. Both are related Digitalis glycosides, but digitoxin is classically associated with purple foxglove, whereas digoxin is chiefly obtained from Digitalis lanata, the woolly foxglove. Digitoxin is also eliminated mainly through the liver, while digoxin is cleared largely by the kidneys.