Digitalis
Digitalis ferruginea
Digitalis grandiflora
Digitalis lanata
Digitalis lutea
Digitalis obscura
Digitalis purpurea
</table>
Digitalis is a genus of about 20 species of herbaceous biennials, perennials and shrubs in the foxglove family
Scrophulariaceae. The members of this genus are known in English as
foxgloves. They are native in
Europe, northwest
Africa and west and central
Asia. The scientific name means "finger", and refers to the ease which a flower of
Digitalis purpurea can be fitted over a human fingertip. "Foxglove" has a similar origin, seen as a suitable glove for a
fox paw.
The flowers are produced on a tall spike, are tubular, and vary in colour with species, from purple to pink, white and yellow.
The best-known species is the Common foxglove,
Digitalis purpurea. It is a biennial, often grown as an ornamental plant due to its
violet flowers. The first year of growth produces only the long basal leaves, while in the second year the erect leafy stem 0.5-2.5m tall develops.
Medicinal use
The use of Digitalis purpurea extract containing cardiac glycosides for the treatment of heart conditions was first described by William Withering. In contemporary medicine, a purer form of digitalis is used to strengthen cardiac contractility and regulate heart rhythm. It is therefore often prescribed for patients in heart failure.
A group of pharmacologically active compounds are extracted mostly from the leaves of the second year's growth, and in pure form are referred to by common chemical names such as digitoxin or digoxin, or by brand names such as Lanoxin, or Purgoxin.
Digitalis is a classic example of a drug derived from a plant formerly used by folklorists and herbalists: herbalists have largely abandoned its use because of its narrow therapeutic index and the difficulty of determining the amount of active drug in herbal preparations. Once the usefulness of digitalis in regulating pulse was understood, it was employed for a variety of purposes, including the treatment of epilepsy and other seizure disorders, now considered inappropriate.
"Digitalis intoxication" results from an overdose of digitalis and can result in jaundiced vision and the appearance of blurred outlines, as well as, in extreme cases, bradycardia. Because a frequent side effect of digitalis is reduction of appetite, some individuals have abused the drug as a weight loss aid.
