Foxglove is a poisonous plant that is protected by law. Already in the 18th century, it found medical use against heart failure. In traditional medicine, ingredients of foxglove are still a proven remedy for heart disease today.
Occurrence and cultivation of foxglove
Foxglove grows as a biennial, herbaceous plant and grows up to two meters high. It blooms from June to August. Foxglove, Latin Digitalis, is a genus of plant in the plantain family (Plantaginaceae). The Latin name Digitalis is derived from the word digitus for finger and refers to the flowers, which resemble a foxglove in shape. The most common in Central Europe is the red foxglove (Digitalis purpurea). Other foxglove species also occur in Europe and include the large-flowered foxglove, yellow foxglove, and woolly foxglove. All parts of the plant are very poisonous, although all foxgloves are similar in effect and toxicity. Foxglove grows as a biennial, herbaceous plant and grows up to two meters high. It blooms from June to August. The flowers of the terminal, racemose inflorescence are purple in red foxglove or rarely white in color. The flower colors of the other foxgloves are yellow to grayish-yellow. The plant is found mainly in forest clearings, forest edges and clear-cuts. As an ornamental plant, foxglove has also been planted in parks and gardens since the 16th century.
Effect and application
In the 18th century, the English physician William Withering discovered the effect of foxglove on patients with dropsy. He is considered a pioneer of the medicinal use of foxglove. However, external use of foxglove leaves was first mentioned in the 12th century for the treatment of ulcers. Later, foxglove was also used as an emetic, although the effect was probably due to poisoning and was often fatal. The plant thus fell into disrepute and only regained importance in therapy through Withering. By investigating different dosages of foxglove, he distinguished for the first time between therapeutic and toxic effects. The effect of foxglove is based on various cardiac glycosides such as the so-called digitoxin, which are contained in the plant. These cardiac glycosides bind to a specific enzyme, sodium–potassium ATPase, in the cells of the heart muscle. This enzyme is thereby inhibited in its activity. This results in an accumulation of calcium in the cells of the heart muscle. This prevents the heart muscle from slackening and stimulates the weakened heart muscle to contract more strongly. The performance of the heart is strengthened, thus the heart rate slows down. In addition, the excitation conduction of the heart is delayed. Cardiac glycosides are usually extracted from red foxglove or woolly foxglove. Preparations containing cardiac glycosides from foxglove are used in cases of cardiac insufficiency, palpitations and arrhythmias, as well as in cases of [[angina pectoris]] or edema resulting from cardiac insufficiency. Digitalis preparations have a very long half-life. Digitoxin has a half-life of one week, which means that after this time half of the active ingredient has decomposed. For therapy with foxglove, standardized digitalis preparations must be used, where the exact concentration of the active ingredient is known. The use of teas or tinctures of foxglove is not recommended, as the content of cardiac glycosides can vary greatly in these. Standardized digitalis preparations are available for internal use as tablets, drops and ampoules. Contact with the leaves of the foxglove plant may cause allergy-like skin rashes.
Health significance, treatment and prevention.
Lowering the heart rate, such as in certain forms of cardiac arrhythmia, is the first priority in therapeutic use. For this purpose, digitalis preparations are the drug of choice. In cases of cardiac insufficiency, it is used when other drugs such as ACE inhibitors or beta blockers no longer have sufficient effect on their own. The positive effects of digitalis preparations are only seen when the heart is diseased or weakened. In a healthy heart, cardiac glycosides have no effect apart from undesirable side effects. Since the consumption of just two foxglove leaves can lead to fatal poisoning, self-medication is strongly discouraged.Since the plant has a very bitter taste, poisoning by consumption is rather rare. Due to its high toxicity, foxglove is hardly used in naturopathy. Only in homeopathy is foxglove administered under the name Digitalis in the potencies D6 to D12. Due to the dilution levels, toxic effects no longer occur. In orthodox therapy with digitalis preparations, the dose must be carefully adjusted because the active ingredients accumulate in the body. In addition, the dosage at which the drugs take effect is close to an already toxic dose. Therefore, the first signs of poisoning with nausea, vomiting, dizziness and low pulse may occur more frequently. Severe poisoning with digitalis results in visual disturbances, impaired consciousness, disorientation and a drop in blood pressure, and even cardiac arrest and death. Possible side effects of digitalis therapy also include cardiac arrhythmias, digestive problems, and nervous disorders. Because of the side effects and the risks of poisoning, preparations containing digitalis require a prescription, and therapy must be monitored by experienced physicians. In the event of side effects, patients must not adjust the dosage on their own under any circumstances, but should consult their physician immediately. However, because digitalis preparations are proven, effective, and inexpensive cardiac medications, therapy can be beneficial and safe for patients when treated by an experienced physician.
