Digitalis

Scientific Name(s): Digitalis lanata Ehrh, Digitalis purpurea L.
Common Name(s): Dead man's bells, Digitalis, Fairy cap, Fairy finger, Foxglove, Lady's thimble, Lion's mouth, Purple foxglove, Scotch mercury, Throatwort, Witch's bells, Woolly foxglove

Medically reviewed by Drugs.com. Last updated on Nov 1, 2021.

Clinical Overview

Use

Digitalis has long been used as a treatment for heart failure in addition to a range of other traditional uses. The plant is cultivated as an ornamental.

Dosing

Digitalis leaf has a narrow therapeutic index, requiring close medical supervision for safe use. Traditional dosage starts at 1.5 g of leaf divided into 2 daily doses. Purified digoxin is typically used at daily doses of 0.125 to 0.25 mg.

Contraindications

Do not allow children to come into contact with the potentially lethal plant.

Pregnancy/Lactation

Documented adverse cardiac reactions. Avoid use.

Interactions

There are numerous interactions with digoxin and digitalis glycosides, ranging from relatively minor (eg, cimetidine, triamterene) to life-threatening (eg, amiodarone, furosemide, verapamil).

Adverse Reactions

Adverse reactions are generally related to toxicity.

Toxicology

All parts of the plant are toxic. The incidence of digitalis toxicity in therapeutic use has been estimated to range from 5% to 25%. Ingestion of extremely small amounts of the plant may be fatal to humans, especially children, and to animals. Toxicity is cumulative.

Scientific Family

• Scrophulariaceae (figworts)

Botany

Digitalis is typically a biennial plant but may be annual or perennial depending on the species. It is characterized by a thick, cylindrical, downy stem that reaches a height of up to 2 m. Leaves form a thick rosette during the first year of growth. The leaves, which are woolly, veined, and covered with white hairs on the underside, have a very bitter taste. Flowers grow in the first or second year, depending on the species, and are tubular and bell-shaped, growing to 8 cm in length. Many colors of flowers have been bred from digitalis, and they are rarely white. Digitalis is native to the British Isles, western Europe, and parts of Africa, but is found today as an ornamental plant throughout the world. Related species that have found some use in traditional medicine include Digitalis lutea (straw foxglove), Digitalis grandiflora and Digitalis ambigua (yellow foxglove), and Digitalis ferriginea (rusty foxglove).Morton 1997, USDA 2010, Warren 2005

History

Digitalis was one of the many herbal remedies used by the ancient Romans. Although its use for the treatment of heart failure has been traced back to 10th century Europe, digitalis was not widely used for this indication until its scientific investigation by British physician William Withering in the late 1700s. For most of the 1800s, digitalis was used to treat a wide variety of diseases and disorders. In 1875, German chemist Oswald Schmiedeberg first isolated pure digitoxin from digitalis, leading others to extract and identify other glycosides from various species of digitalis. In 1957, digoxin was isolated from D. lanata and is now a major cardiac glycoside marketed in tablet form. Digitalis was admitted into the first edition of the Pharmacopeia of the United States (1820) and is currently recognized by all major pharmacopeias. In South America, preparations of the powdered leaves are used to relieve asthma, as sedatives, and as diuretic/cardiotonics. In India, an ointment containing digitalis glycosides is used to treat wounds and burns.Belcastro 2002, <...