Digoxin vs. Digitalis — What's the Difference?

Digoxin is a purified cardiac glycoside extracted from the leaves of Digitalis lanata or sometimes Digitalis purpurea. It is used in the treatment of various heart conditions, including atrial fibrillation, atrial flutter, and sometimes heart failure that cannot be controlled by other medication. Digoxin works by increasing the force of heart contractions, which can be beneficial in improving heart function and controlling heart rate. On the other hand, Digitalis is a genus of plants, commonly called foxgloves, which are known for their heart-active glycosides. These plants have been used medicinally for centuries to treat heart conditions but require careful dosing due to their narrow therapeutic index.

While digoxin is a specific compound with well-defined dosages and administration methods for therapeutic use in heart disease, Digitalis plants contain a variety of cardiac glycosides, not all of which are used medically. The therapeutic compounds in Digitalis plants must be carefully extracted and purified to be used safely as medication due to their potency and potential toxicity.

The mechanism of action of digoxin involves inhibiting the sodium-potassium ATPase pump in heart cells, which leads to an increase in intracellular calcium concentrations and stronger heart muscle contractions. This effect can improve heart function and control the rate at which the heart beats. In contrast, while the Digitalis genus includes species that are sources of digoxin and other cardiac glycosides, the use of the plant itself in medicine requires precise knowledge of its glycoside content to avoid toxicity.

Digoxin's clinical use is carefully monitored to avoid side effects, which can include nausea, vomiting, dizziness, and visual disturbances, among others. Its therapeutic window is narrow, meaning the difference between effective and toxic doses is small. In comparison, Digitalis plants, if not used correctly, can cause severe toxicity, including heart arrhythmias, gastrointestinal disturbances, and even death.

Digoxin represents a specific, clinically used derivative of Digitalis plants, optimized for safety and efficacy in treating certain heart conditions. The distinction between digoxin and Digitalis is crucial in medical practice, highlighting the difference between a pharmaceutical agent and the natural source from which it is derived.