Digoxin and Foxglove – From 1785 to Today, a Story from Healers to Modern Medicine

In the 1930s, physician and historian Ralph Major said: “Digoxin is undoubtedly the most valuable heart drug discovered and one of the most valuable drugs in the entire pharmacopoeia.”

Digitalis purpurea, also known as foxglove, is a flowering plant native to much of Europe. For centuries, foxglove was known to have various effects on the human body. British botanist and physician William Withering became famous for testing it to treat oedema, the swelling and fluid accumulation caused by heart failure.

Heart failure is a condition in which the heart cannot pump enough blood to the body and lungs. As a result, the body receives insufficient oxygen and nutrients, organs cannot function properly, and symptoms such as shortness of breath and oedema often develop.

Causes of heart failure include:

1. Coronary artery disease: Results from narrowing or blockage of the coronary arteries supplying the heart muscle.
2. High blood pressure: Persistently high pressure makes the heart work harder and weaken over time.
3. Heart muscle diseases: Known as cardiomyopathies, these conditions weaken or stiffen the heart muscle.
4. Heart valve diseases: Narrowing or leakage of heart valves makes the heart work harder and weaken over time.
5. Abnormal heart rhythms: Rhythms such as tachycardia or bradycardia prevent the heart from pumping enough blood.
6. Other factors: Other causes of heart failure include diabetes, obesity, sleep apnoea and thyroid disease.

Science Beginning with Observation

Withering first learned about using digoxin (as the active ingredient was later named) from an elderly woman who worked as a folk healer. Her mixture contained 20 different ingredients that helped treat oedema. Withering identified foxglove as the important ingredient. In 1785, he published his trials in patients, together with warnings of fatal toxicity at high doses, in “An Account of the Foxglove and Some of Its Medical Uses”, his book. 

Foxglove's main toxins are digitoxin and digoxin. At appropriate doses, however, these toxins:

• Increase intracellular calcium levels
• Increase the strength of heart muscle contractions and 
• Act as antiarrhythmic agents to control heart rate
• Blood flow to the kidneys improves and 
• Accumulated fluid is eliminated through the bladder

Author H. Panda commented: “His carefully controlled experiments not only gave the world an important heart drug (one that slows and strengthens the heartbeat, improves circulation and removes excess fluid) but also provided an example for reviving pharmacognosy, the study of plants or natural substances as potential sources of drugs. Withering's efforts gave renewed momentum to the journey of pharmacognosy begun by Dioscorides 1,700 years earlier.”

Description of the article image: Digitalis purpurea, known as foxglove

Historical figures mentioned in the article: William Withering (1741–1799)

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