Description
Medicinal Parts
The medicinal parts are the dried leaves (in powder form), the ripe dried seeds, the fresh leaves of the 1-year-old plant or the leaves of the 2-year-old plant collected at the beginning of flowering. In the past, the drug of Digitalis purpurae was the raw material employed in isolating the cardiac glycosides. Today, Digitalis lantana is used.
Flower and Fruit
The flowers are carmine red with white-edged spots on the inside. The flowers appear in long hanging racemes. They have 5 free, short-tipped sepals. The corolla is about 4 cm long, campanulate, bilabiate with an obtuse upper lip and an ovate tip on the lower lip. The flower is glabrous on the outside and has a white awn on the inside. There are 2 long and 2 short stamens, and 1 superior ovary. The fruit is a doublevalved, ovate, glandular, villous capsule.
Leaves, Stem, and Root
The plant is a biennial with a branched tap root. In the first year it develops a leaf rosette. In the second it produces a 2 m high, erect, unbranched, gray, tomentose stem. The leaves are alternate, ovate, tapering upward, and petiolate. Almost all leaves are crenate; only the highest ones are entire-margined.
Characteristics
The plant is very poisonous; it tastes hot-bitter with a slightly unpleasant odor.
Habitat
Digitalis is indigenous to Europe. It was introduced to the east and the American continent.
Production
Digitalis leaves are the leaves of Digitalis purpurea or Digitalis lanata. The latter corresponds to Digitalis purpurea but has a milder effect. The rose leaves are harvested during the first period of vegetation in early autumn. The drying period is decisive for the content of cardenolide glycosides. The temperature for drying is 30º C to 50º C.
Not to be Confused With
Confusion seldom occurs due to cultivation under controlled conditions.
Other Names
Dead Men's Bells, Dog's Finger, Fairy Caps, Fairy Fingers, Fairy Gloves, Fairy Thimbles, Finger Flower, Folks' Glove, Foxglove, Gloves of Our Lady, Ladies' Glove, Lion's Mouth, Virgin's Glove, Witches' Gloves,
Actions & Pharmacology
Compounds
Cardioactive steroid glycosides (cardenolides 0.5 to 1.5%): including ones of the -
- A-sequence (aglycone digitoxigenin): purpurea glycoside A (primary glycoside), digitoxin (secondary glycoside)
- B-sequence (aglycone gitoxigenin): purpurea glycoside B (primary glycoside), gitoxin (secondary glycoside), Digitalinum verum
- E-sequence (aglycone gitaloxigenin): glucoverodoxin, glucogitaloxin, gitaloxin
Pregnane glycosides: including digipurpurin, diginin, digitalonin
Steroid saponin: including desgalactotigonin, digitonine, purpureagitoside
Anthracene derivatives: anthraquinones
Effects
The drug contains cardioactive cardenolide glycosides that are positively inotropic, negatively chronotropic, and improve the contraction power of cardiac muscle.
Indications & Usage
Unproven Uses
In folk medicine, the drug's use originated in Ireland, then came to Scotland and England and finally to central Europe. It was used to treat tumors in the lower abdomen, ulcers, headaches, abscesses, and paralysis. Externally, the drug was used for the granulation of poorly healing wounds and to cure ulcers. Furthermore, the drug was used for cardiac insufficiency, especially high blood pressure.
Use of the raw product has become obsolete because the effect is not reproducible. The use of pure glycosides is recommended instead. Digitoxin is available in mono preparations (extract) and is used as an isolated pure substance.
Homeopathic Uses
Digitalis purpurea is used for cardiac insufficiency and migraine.
Precautions & Adverse Reactions
General
Because of the narrow therapeutic range of digitalis glycosides, a certain percentage of patients may experience side effects immediately upon administration of therapeutic dosages: hypertonia in gastrointestinal area, loss of appetite, vomiting, diarrhea, and headache.
Contraindicated
Neither the drug nor pure glycosides should be administered in the presence or first- or second-degree AV-block, hypercalcemia, hypokalemia, hypertrophic cardiomyopathy, carotid sinus syndrome, ventricle tachycardia, thoracic aortic aneurysm, or WPW syndrome.
Drug Interactions
Major Risk
Thiazide Diuretics
Concurrent use may result in digitalis toxicity (nausea, vomiting, arrhythmias). Clinical Management: Patients given diuretics with digitalis should be told to add sources of potassium to their diet or they should be given potassium supplements, even if their serum potassium is normal.
Potential Interactions
The simultaneous administration of arrhythmogenic substances (sympathomimetics, methylxanthines, phosphodiesterase inhibitors, quinidine) increases the risk of cardiac arrhythmias.
Overdosage
With overdosage, in addition to the already-mentioned symptoms, the following can also occur:
Heart
cardiac rhythm disorders, all the way up to life-threatening ventricular tachycardia and atrial tachycardia with atrioventricular block
Central nervous system
stupor, visual disorders, depression, confused states, hallucinations, psychoses
Lethal dosages lead to heart failure or asphyxiation. Administration over extended periods leads in rare cases to gynecomastia. Because of the difficulties in standardizing the drug, the administration of pure glycosides is to be preferred (digitoxin).
The first measures to be taken in case of poisoning are gastric lavage and activated charcoal instillation. All other measures proceed according to the symptoms. For loss of potassium, careful replenishment is necessary. For ectopic irritation buildup in the ventricle, administration of phenytoin as an antiarrhythmatic is recommended. Lidocaine should be used in cases of ventricular extrasystole; atropine is recommended for partial atrioventricular block. The prophylactic installation of a pacemaker is often necessary. Hemoperfusion for the elimination of the glycosides and cholestyramine administration for the interruption of the enterohepatic circulation are possible.
The drugs and pure glycosides should be administered in the following situations (among others): atrioventricular block of the 2nd and 3rd degree, hypercalcaemia, hypocalcaemia, hypertrophic cardiomyopathy, carotid sinus syndrome, ventricular tachycardia, thoracic aortic aneurysm, WPW-syndrome.
Dosage
Mode of Administration
Today, the drug is obsolete. Due to the lack of reproductivity of content, the use of appropriate pure glycosides is advisable. Digitoxin is contained in mono preparations (extract) and used as an isolated pure substance.
Preparation
Tincture: shaken for 1 day in 25% ethanol at a ratio of 1:10.
The manufacture of the digoxin and digitoxin is a complicated process that involves fermentation, extraction and evaporation.
Storage
Store carefully away from sources of light.
