Digitoxin

Digitoxin

File:Digitoxin structure.svg

Chemical structure of Digitoxin

Digitoxin is a cardiac glycoside that is derived from the Digitalis plant, commonly known as foxglove. It is used in the treatment of certain heart conditions, particularly heart failure and atrial fibrillation. Digitoxin works by increasing the force of contraction of the heart muscle, thereby improving cardiac output.

Mechanism of Action

Digitoxin exerts its effects by inhibiting the sodium-potassium pump (Na_/K_-ATPase) in cardiac cells. This inhibition leads to an increase in intracellular sodium levels, which in turn affects the sodium-calcium exchange mechanism, resulting in increased intracellular calcium. The elevated calcium levels enhance the contractility of the heart muscle, a phenomenon known as positive inotropic effect.

Pharmacokinetics

Digitoxin is characterized by its long half-life, which can range from 5 to 7 days. It is primarily metabolized in the liver and excreted in the bile. Unlike digoxin, another cardiac glycoside, digitoxin is not significantly excreted by the kidneys, making it a suitable option for patients with renal impairment.

Clinical Uses

Digitoxin is used in the management of chronic heart failure and certain types of arrhythmias, such as atrial fibrillation. It helps to control the heart rate and improve symptoms of heart failure by enhancing cardiac output.

Side Effects

Common side effects of digitoxin include nausea, vomiting, diarrhea, and dizziness. More serious side effects can occur, such as arrhythmias, bradycardia, and digitalis toxicity. Monitoring of blood levels and clinical symptoms is essential to avoid toxicity.

Digitalis Toxicity

Digitalis toxicity is a serious condition that can occur with digitoxin use, especially in cases of overdose or in patients with impaired metabolism. Symptoms of toxicity include gastrointestinal disturbances, confusion, visual changes, and cardiac arrhythmias. Treatment involves discontinuation of the drug and administration of digoxin-specific antibody fragments if necessary.

Related Pages

• Digitalis
• Digoxin
• Heart failure
• Atrial fibrillation
• Cardiac glycoside