Digoxin

Question 1

What is digoxin used for? What class is it?

Answer 1

Cardiac Glycoside

Used in AF, tachycardia, heart failure

Question 2

Is digoxin a positive or negative inotrope?

Answer 2

A positive inotrope - increases the force of myocardial contraction and reduces conductivity within the AV node

Question 3

What is the desired serum concentration for digoxin?

What conc indicates toxicity?

Answer 3

1-2mcg/L

1.5-3mcg indicates toxicity

Question 4

What to monitor in digoxin?

Answer 4

Serum electrolytes (especially potassium) and renal function

Question 5

Why is it important to monitor potassium in digoxin?

Answer 5

Narrow therapeutic index - Possibility of digitalis toxicity, made worse by hypokalaemia. Managed by giving potassium sparing diuretics or potassium supplements.

Elderly more sus to digitalis toxicity

Question 6

Digoxin side effects

Answer 6

N+V
Diarrhoea
Dizziness
Blurred vision (yellow)

Question 7

Digoxin interactions

Answer 7

Amiodarone - increases plasma conc. of digoxin

CCBs - increases plasma conc. of digoxin

Erythromycin - increases plasma conc. of digoxin (enzyme inhibitor)

Rifampicin - reduces plasma conc. of digoxin (enzyme inducer)

St John’s Wort - reduces plasma conc. of digoxin (enzyme inducer)

Diuretics - can cause hypokalaemia - digitalis toxicity