digitalis

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digitalis

(dĭj'ĭtăl`ĭs), any of several chemically similar drugs used primarily to increase the force and rate of heart contractions, especially in damaged heart muscle. The effects of the drug were known as early as 1500 B.C.; it was later obtained from the foxglove plant, Digitalis purpurea, and from fuchsia (see figwortfigwort,
common name for some members of the Scrophulariaceae, a family comprising chiefly herbs and small shrubs and distributed widely over all continents. The family includes a few climbing types and some parasitic and saprophytic forms.
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). It was used in the 19th cent. to treat dropsy (edemaedema
, abnormal accumulation of fluid in the body tissues or in the body cavities causing swelling or distention of the affected parts. Edema of the ankles and lower legs (in ambulatory patients) is characteristic of congestive heart failure, but it can accompany other
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). Digitalislike substances are found in a wide variety of plants and animals, including the poisons of some toad species. Foxglove remains the main source for the drug used medically today.

Chemically, digitalis is composed of a sugar (glycoside), a steroid, and a cyclic ester known as a lactone; the pharmacological activity varies according to differences, occurring naturally or introduced synthetically, in the steroid or sugar portions. Common preparations include digitalis, digitoxin, and digoxin, all from foxglove, and ouabain from Strophanthus gratus, the ouabaio tree; these vary both in solubility and in rapidity and duration of effect.

Digitalis slows the pulse and slows the conduction of nerve impulses in the heart. By increasing the amount of calcium available to the heart muscle, it improves the force of each heartbeat and increases the amount of blood pumped. It is used in the treatment of congestive heart failurecongestive heart failure,
inability of the heart to expel sufficient blood to keep pace with the metabolic demands of the body. In the healthy individual the heart can tolerate large increases of workload for a considerable length of time.
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 and cardiac arrhythmiasarrhythmia
, disturbance in the rate or rhythm of the heartbeat. Various arrhythmias can be symptoms of serious heart disorders; however, they are usually of no medical significance except in the presence of additional symptoms.
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. The mechanism by which it acts to enhance heart muscle contraction is not definitely known. Toxic effects include nausea, vomiting, and visual disturbances.

Digitalis

(religion, spiritualism, and occult)

The dried leaf of the common foxglove (Digitalis purpurea). In 1775 William Witherington, a physician of Birmingham, England, learned of its effectiveness for heart conditions from an old Witch in Shropshire. It was one of several ingredients in her cures, and Witherington managed to isolate digitalis as the main active ingredient. He went on to make many contributions to medicine, and a monument was raised to him at Edgbaston Old Church. The carved decorations on that monument are of the foxglove.

Prior to Witherington's application of its use, country wise women used foxglove to treat many maladies, including epilepsy and tuberculosis. Nicholas Culpeper suggests it is "one of the best remedies for a scabby head," while Meyer warns it is "too dangerous for domestic use or self-medication." It certainly is extremely poisonous. Old folk names for it were Witch's Bells and Deadmen's Bells.

Three cardiac glucosides have been isolated from digitalis: digitoxin, gitoxin, and gitalin. No synthetic drugs can duplicate the action of the glycosides in foxglove in treating heart failure. Digitalis is recommended in congestive heart failure from any cause, although prolonged use leads to cumulation of the drug because of its slow excretion and destruction. Because of this, side effects can occur, including greater cardiac irregularities.

Digitalis

 

a genus of plants of the family Scrophulariaceae. Plants of this genus are perennial or biennial grasses; rarely are they subshrubs or shrubs. The alternate, entire leaves are lanceolate or oblong. The yellow, purple, or yellow-brown flowers are irregular and often large; they are generally in dense terminal racemes. The perianth is five-parted; the bilabiate corolla is campanulate, thimble-shaped, or inflated. The fruit is a capsule.

There are approximately 35 species of Digitalis, distributed in Europe, western Asia and northern Africa; the Mediterranean region abounds in Digitalis. Of the six species found in the USSR, four grow only in the Caucasus and two grow in the Caucasus, the European USSR, and Western Siberia. They are found primarily in hardwood and mixed forests and in meadows, thickets, and pastures; they also grow on slopes.

All species of Digitalis are poisonous because they contain glycosides, primarily in their leaves. Some species are valuable medicinal herbs. These species include common foxglove (Digitalis purpurea) and yellow foxglove (D. grandiflora), which grow in the European USSR, the Caucasus, and the southern part of Western Siberia; Grecian foxglove (D. lanata), which grows in the Transcarpathian and Odessa oblasts; and such Caucasian species as rusty foxglove (D. ferruginea), D. Schischkinii, and D. ciliata.

The glycosides in the leaves regulate heart activity, increase urine elimination, and reduce edema. Medicinal preparations in the form of powders, tinctures, extracts, and neogalenic preparations (such as gitalen) are made from dried leaves, as are secondary glycosides (digitoxin, digoxin). Digitalis preparations are used under strict medical supervision for treating heart disease. Some species of Digitalis are ornamentals.

In the USSR, common foxglove is cultivated in Krasnodar Krai and Western Siberia; Grecian foxglove is raised in the Northern Caucasus and the Ukraine. Good yields are obtained on light chernozem soils. Foxglove should be planted on fields that have lain fallow or on which winter crops, annual hay grasses, and well-fertilized industrial and other row crops were previously cultivated. The seeds are generally sown 60 cm apart in the fall or spring; the sowing rate is 6–7 kg of seeds per hectare. Organic and inorganic fertilizers are applied during plowing. In the first and second years, the plants require nitrogen and phosphorous supplements.

Under optimum weather conditions and agricultural methods, the leaves may be gathered two or three times in the first year and one or two times in the second. The leaves of annual crops may be harvested first in July or August and later at intervals of one to 1 x/i months. The leaves of biennial foxglove may first be picked between shoot formation and flowering and later during massive flowering.

REFERENCES

Naperstianka. Moscow, 1954.
Atlas lekarstvennykh rastenii SSSR. Moscow, 1962.
Lekarstvennye rasteniia SSSR kul’tiviruemye i dikorastushchie. Edited by A. A Khotin [et al.]. Moscow, 1967.

T. V. EGOROVA

digitalis

[dij·ə′tal·əs]
(pharmacology)
The dried leaf of the purple foxglove plant (Digitalis purpurea), containing digitoxin and gitoxin; constitutes a powerful cardiac stimulant and diuretic.

Digitalis

[dij·ə′tal·əs]
(botany)
A genus of herbs in the figwort family, Scrophulariaceae.

digitalis

1. any Eurasian scrophulariaceous plant of the genus Digitalis, such as the foxglove, having bell-shaped flowers and a basal rosette of leaves
2. 
a. a drug prepared from the dried leaves or seeds of the foxglove: a mixture of glycosides used medicinally to treat heart failure and some abnormal heart rhythms
b. any cardiac glycoside, whatever its origin