Foxglove ( Digitalis purpurea ) is a plant of the Scrophulariaceae family. With its cardiokinetic properties, it is useful for the health of the heart and the circulatory system. Let’s find out better.
Ownership of digital
Digitalis leaves contain some glycosides (digitoxin and digoxin), responsible for the cardiokinetic property. These active ingredients increase the contraction force of the heart muscle (positive inotropic effect) and decrease the number of contractions (antiarrhythmic effect), thus making the ventricular systole more energetic and the diastole wider and more complete.
The result is an increase in cardiac output with an improvement in the functionality of the heart and circulatory system. In other words, at the right dosage, the digitalis toxin increases the heart rate, the symptoms of heart failure tend to disappear, edema is reabsorbed and diuresis is restored .
However, digitoxin, digoxin and many other cardioactive glycosides contained in the phytocomplex of the plant, have demonstrated the deadly effect of overdose: a slight increase in these substances can make a difference, as the therapeutic dose is about 50-60% of that fatal.
Digitalis poisoning can manifest itself with disturbances of the sense organs, usually ocular, such as yellow or blue vision and with the appearance of confused contours (halos); bradycardia; nausea and vomiting; diarrhea ; tachycardia ; fibrillation. The possible onset of atrioventricular block can lead to cardiac arrest and death.
Digitalis is a classic example of a drug derived from a plant, but given the high toxicity compared to the therapeutic effect and the difficulty in determining the active dose, its herbal use has been abandoned. Initially, once the usefulness of digitalis in regulating the pulse was ascertained, the plant was used to treat a large number of diseases, including epilepsy and other seizure disorders. Now for these indications its use is considered inappropriate.
How to use
Digitalis should only be used as a ready-to-use drug. It is not possible to prepare herbal teas with the leaves or flowers of digitalis, as it could be toxic. At the pharmacy you can buy digoxin-based tablets with a cardiotonic effect.
Contraindications of digitalis
Digitalis is contraindicated in the case of subjects who have known hypersensitivity to the active ingredient and in case of previous digitalis intoxication.
Furthermore, digitalis should be avoided in patients with ventricular fibrillation, obstructive hypertrophic cardiomyopathy and accompanied Wolff-Parkinson-White syndrome.
Description of the plant
More or less tomentose biennial herbaceous plant with simple stems 20-150 cm high.
It has large and long petiolate basal leaves, the others gradually decreasing, are arranged in a spiral; simple, 10–35 cm long and 5–12 cm broad, gray-green in color; downward curved, with a finely notched margin, and rough surface; in the first year they form a tight rosette at ground level.
The flowering stem develops in the second year, and reaches a height of 1–2 m.
The flowers are arranged in terminal clusters, are tubular, hanging, of a purple red color (but there are pink, yellow or white varieties), with purple spots inside.
The fruit is a capsule which, when ripe, opens, releasing numerous very small seeds.
It grows in fresh mountain and sub-mountain forests and in the arid meadows of central-southern Europe, often wild.
In ancient times it was known by Theophrastus, than by Pliny, more for its ornamental character than anything else.
At the end of the sixteenth century. the Strasbourg doctor Jodocus Marchius Montesio di Berg was the first to mention the therapeutic virtues of digitalis, in the work De simplicium medicamentorum facultatibus, as a laxative and astringent remedy ; however the cardiokinetic properties, used today, were unknown both to him and to his contemporaries. Clinical research of the eighteenth century. came to the discovery of the pharmacological effect of digitalis on heart failure.
The Parma doctor Giovanni Rasori attributed to the plant a ” counter -stimulating” action capable of improving some pathologies such as dropsy , pulmonary haplopexia and fevers caused by typhus. The mechanism of action, however, continued to be unknown despite Rasori observed a markedly diuretic effect at the same time as the therapeutic activity: he did not know whether this action was the consequence of a stimulus on the kidneys or an increase in blood fluids.
His contemporary, Withering , was the first to discover the cardiokinetic activity of digitalis, capable of slowing down the rhythm of the heart, regulating it; and concluded that his diuretic action must depend on the better conditions of the circulatory system .
This discovery gave rise to new nineteenth-century plant studies . which led to the isolation of its glucosidic active ingredients : the so-called digitalis.