Foxglove Health Article

Description

Foxglove, also called Digitalis purpurea, is a common biennial garden plant that contains digitoxin, digoxin, and other cardiac glycosides. These are chemicals that affect the heart. Digitalis is poisonous; it can be fatal even in small doses. It was the original source of the drug called digitalis.

Foxglove is a native of Europe. It was first known by the Anglo-Saxon name foxes glofa (the glove of the fox), because its flowers look like the fingers of a glove. This name is also thought to be related to a northern legend that bad fairies gave the blossoms to the fox to put on his toes, so that he could muffle his footfalls while he hunted for prey. The legend may account in part for some of the common names of digitalis: dead man's bells, fairy finger, fairy bells, fairy thimbles, fairy cap, ladies' thimble, lady-finger, rabbit's flower, throatwort, flapdock, flopdock, lion's mouth, and Scotch mercury.

Foxglove was first introduced to the United States as an ornamental garden plant. During the first year, foxglove produces only leaves. In its second season it produces a tall, leafy flowering stalk that grows 3–4 ft (0.9–1.2 m) tall. In early summer, many tubular, bell-shaped flowers bloom; they are about 2 in (5.08 cm) long and vary in color from white to lavender and purple.

Foxglove was originally used for congestive heart failure and atrial fibrillation (chaotic contractions across the atrium of the heart). Foxglove helps the muscles of the heart to contract, reduces the frequency of heartbeats, and lowers the amount of oxygen the heart needs to work. The cardiac glycosides in foxglove block an enzyme that regulates the heart's electrical activity. The dried leaves, ripe dried seeds, and fresh leaves of the one-year-old plant, or the leaves of the two-year old plant are the parts that were used in medicine.

In spite of its use in the past, foxglove has been largely replaced as a heart medicine by standardized pharmaceutical preparations because it is one of the most dangerous medicinal plants in the world. Foxglove is, in fact, a useful example of the importance of standardization in testing the efficacy and possible toxicity of present-day popular herbal medicines. Its sap, flowers, seeds, and leaves are all poisonous; the leaves, even when dried, contain the largest amount of cardiac glycosides. The upper leaves of the stem are more dangerous than the lower leaves. Foxglove is most toxic just before the seeds ripen. It tastes spicy hot or bitter and smells slightly bad.

In folk medicine, foxglove was first used in Ireland. Its use spread to Scotland, England, and then to central Europe. It was taken to treat abscesses, boils, headaches, paralysis, and stomach ulcers. It was also applied to the body to help wounds heal and to cure ulcers. It has not been proven to be an effective treatment for any of these ailments.

In 1775, William Withering, an English doctor, first discovered the accepted medicinal use of foxglove. He identified digitalis as a treatment for swelling or edema

associated with congestive heart failure. Withering published a paper in 1785 that is considered a classic in the medical literature. Foxglove was used to treat heart disease during the eighteenth and nineteenth centuries.

General use

Foxglove is no longer used as a heart medicine because the therapeutic dose and the lethal dose are very close. Seasonal variations in the level of cardiac glycosides in the plant make the safe dose impossible to estimate except by an experienced physician and prescriber of the herb who monitors the patient on an hourly basis for signs of overdose. Few living doctors and herbalists can safely use digitalis as a plant extract. Specific standardized doses of pharmaceutical digoxin are used instead. Even so, patients receiving the drug must be closely monitored.

Preparations

In present-day usage, foxglove is used as an ingredient in a class of heart drugs called digitalis. Digoxin (Lanoxin) is the most common drug made from digitalis. Digitalis is usually taken orally, as capsules, as an elixir, or as tablets. It can also be given in an injection.