Digoxin

Question 1

Introduction to the drug

Answer 1

• Digoxin increases the strength and efficiency of heart contractions, and is useful in the treatment of heart failure and control the rate and rhythm of the heart. Digoxin increases the force of contraction of the muscle of the heart by inhibiting the activity of an enzyme (ATPase) that controls movement of calcium, sodium, and potassium into heart muscle. Calcium controls the force of contraction. Inhibiting ATPase increases calcium in heart muscle and therefore increases the force of heart contractions. Digoxin also slows electrical conduction between the atria and the ventricles of the heart and is useful in treating abnormally rapid atrial rhythms such as atrial fibrillation, atrial flutter, and atrial tachycardia. During rapid atrial rhythms, electrical signals from the atria cause rapid contractions of the ventricles. Rapid ventricular contractions are inefficient in pumping blood containing oxygen and nutrients to the body, causing symptoms of weakness, shortness of breath, dizziness, and even chest pain. Digoxin alleviates these symptoms by blocking the electrical conduction between the atria and ventricles, thus slowing ventricular contractions

Question 2

Why would you prescribe

Answer 2

• AF

- Heart Failure

Question 3

Pharmacodynamics

Answer 3

• Digoxin is a cardiac glycoside which has positive inotropic activity characterized by an increase in the force of myocardial contraction. It also reduces the conductivity of the heart through the atrioventricular (AV) node.
• Digoxin also exerts direct action on vascular smooth muscle and indirect effects mediated primarily by the autonomic nervous system and an increase in vagal activity.

Question 4

Pharmacokinetics

Answer 4

• Absorption: Absorption from the GI tract is variable.
• Distribution: Widely distributed in tissues, including the heart, brain, erythrocytes, and skeletal muscle. 20-30% bound to plasma proteins.
• Excretion: Excreted mainly unchanged.

Question 5

Side Effects

Answer 5

• nausea,
• diarrhea,
• vomiting,
• headache,
• dizziness,
• skin rash, and
• mental changes.