Digitoxin

Digitoxin is an active substance used to treat chronic heart failure, cardiac arrhythmias and muscular, accommodative (adaptive) or nervous eye fatigue. Digitoxin is a white powder that is insoluble in water. Digitoxin is a natural herbal ingredient from the red foxglove (Digitalis purpurea), which is native to Austria. Digitoxin belongs to the group of cardiac glycosides. Digitoxin is nowadays replaced by other therapies (with ACE inhibitors, beta-blockers, diuretics) and is only rarely used. However, it is still used more frequently, especially in ophthalmology.

Digitoxin increases the contraction force and contraction speed of the heart (positive inotropic). It lowers the heart rate (negative chronotropic), delays conduction (negative dromotropic) and increases the excitability of the heart muscles (positive bathmotropic).

Digitoxin inhibits the enzyme sodium-potassium ATPase (also known as the sodium-potassium pump) in the heart muscle cells. The sodium-potassium pump transports sodium ions out of the cell and potassium ions into the cell, which leads to changes in concentration. An increased potassium concentration in the cell leads to the activation of proteins such as actin and myosin, which are responsible for contraction in muscle cells, including heart muscle cells. This increases the contraction force (inotropy).

Digitoxin also affects the electrical activity of the heart (membrane potential). This results in a delayed electrical conduction time in the heart between the atrium and the AV node, which is referred to as negative dromotropic.

Digitoxin is broken down by the liver and excreted by the kidneys and in the stool. It has a long plasma half-life of up to 8 days, which means that only half of the active substance is excreted after 8 days. This means that it is effective for a very long time. The bioavailability - i.e. the percentage of the active ingredient available in the blood - is also very high due to the fat solubility of the active ingredient.

Always take Digitoxin exactly as described in the package leaflet or as advised by your doctor.

Since even very small amounts of digitoxin are sufficient to achieve a sufficient effect, the maintenance dose for adults is 0.001 mg/kg body weight. The maintenance dose is the dosage that should be taken daily to maintain the effect.

The following side effects may occur:

Immune system:

• Allergic reactions
• Hives (urticaria)
• Eosinophilia
• Reddening of the skin (erythema)
• Reduction in blood platelets (thrombocytopenia)
• Butterfly erythema (lupus erythematosus)

Endocrine system:

• Enlargement of the mammary gland in men (gynecomastia)

Psyche:

• Psychological changes (e.g. nightmares)
• depression
• hallucinations
• psychoses
• Speech disorders
• Weakness
• listlessness (apathy)
• malaise

Eyes:

• Color vision disorders

Cardiovascular system:

• Cardiac arrhythmia
• conduction disturbances

Gastrointestinal tract:

• Loss of appetite
• Nausea and vomiting
• abdominal pain
• Diarrhea
• Vascular occlusion in the abdominal cavity (mesenteric infarction)

Musculoskeletal system:

• Muscle weakness

General:

• Headache
• fatigue
• insomnia

In the case of digitoxin poisoning, the Fab fragment of an antibody can be taken as an antidote.

If the following medicines are taken at the same time, interactions may occur that intensify the effect:

• Calcium
• Drugs that interfere with the electrolyte balance:
  • Diuretics,
  • laxatives
  • Benzylpenicillin
  • Amphotericin B
  • carbenoxolone
  • Corticosteroids
  • ACTH
  • salicylates
  • Lithium salts
• Drugs that slow down the breakdown in the liver:
  • Macrolide antibiotics
  • itraconazole
  • prednisone
  • danazol
  • fluoxetine
  • Medication for HIV treatment(indinavir, ritonavir)
  • verapamil
  • nifedipine
  • diltiazem
  • amiodarone
• Drugs that inhibit the P-glycoprotein:
  • Macrolide antibiotics
  • tetracyclines
  • quinidine
• certain antibiotics:
  • Macrolide antibiotics
  • carbapenems
  • beta-lactams
• beta-blockers
• muscle relaxants
• reserpine
• tricyclic antidepressants
• sympathomimetics
• theophylline

If the following medicines are taken at the same time, interactions may occur that weaken the effect :

• Drugs that increase potassium levels:
  • Spironolactone
  • Potassium canrenoate
  • amiloride
  • triamterene
  • potassium salts
• activated charcoal
• cholestyramine
• colestipol
• Kaolin pectin
• Laxatives
• Drugs that accelerate the breakdown in the liver:
  • Phenylbutazone
  • phenytoin
  • Rifampicin
  • rifabutin
  • spironolactone
  • barbiturates

Digitoxin must not be taken in the following cases:

• in case of allergy to digitoxin or other cardiac glycosides
• in case of suspected poisoning with cardiac glycosides
• in case of ventricular tachycardia or ventricular fibrillation (cardiac arrhythmia)
• in case of AV block II. or III. degree or pathological sinus node function (cardiac arrhythmia)
• in the case of planned electrical cardioversion (regulation of the heartbeat sequence using electricity)
• in case of suspected or existing accessory atrioventricular conduction pathways (WPW syndrome)
• in the case of potassium deficiency in the blood (hypokalemia)
• in the case of increased calcium levels in the blood (hypercalcemia)
• in case of magnesium deficiency in the blood (hypomagnesemia)
• in heart muscle diseases with narrowing of the outflow tract
• in the case of pathological expansion of the aorta in the area of the chest (thoracic aortic aneurysm)
• with simultaneous intravenous administration of calcium salts

Can be used on infants, children and adults.

Digitoxin can be used during pregnancy. There are no reports of malformations. It should be noted that digoxin - a chemically close relative of digitoxin - was used for this purpose. There are no reports on digitoxin. However, the above conclusions can be drawn due to the similarity. However, when used during pregnancy, regular ultrasound and heart rate checks should be carried out on the unborn child.

Digoxin should therefore be used as an alternative to Digitoxin.

Digitoxin should NOT be used during breastfeeding , as no experience reports are available and digitoxin passes into breast milk.

Digoxin should therefore be used as an alternative to Digitoxin.

No symptoms have been observed in breastfed infants during digoxin therapy in nursing mothers, as the amount absorbed is so small that no effects are to be expected. In the case of intravenous administration, a breastfeeding break of 2 hours should be observed, as more active substance is available with intravenous administration.

Digitoxin is extracted from the red foxglove (Digitalis purpurea). The first applications were described as early as 1775 . Oswald Schmiedeberg was the first to isolate digitoxin in 1875, and Adolf Otto Reinhold Windaus succeeded in fully elucidating its structure in 1962 .