DIGOXIN

Cardiac glycoside that increases the force of contraction of the heart muscle and reduces conductivity within the atrioventricular (AV) node. It has a slow onset of action and response may take hours to show so it is not suitable for rapid control of heart rate.

Dosage Forms

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Tablet

62.5 µg
250 µg

Injection

250 µg/ml

Uses

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  • Heart failure
  • Supraventricular arrhythmias: atrial fibrillation and flutter

Dose and Duration

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Atrial fibrillation or flutter
Adult: For rapid digitalisation; 0.75‒1.5 mg orally in divided doses over 24 hours
Child: 0.3‒2 mg/kg rectally every 6‒8 hours (max. 150 mg daily)

Maintenance dose: 125‒250 micrograms daily

Heart failure

In urgent situations

Adult: By IV infusion, loading dose 250 micrograms IV over at least 2 hours; give 3-4 times in the first 24 hours

In non-urgent situations

Adult: loading dose, 0.5-1 mg orally daily in 2-3 divided doses for 2-3 days.

Maintenance dose: 250 micrograms orally daily

Elderly: 125 micrograms daily
Child: loading dose, 15 micrograms/kg orally 3-4 times dai ly for 2-4 days.

Maintenance dose: 15 micrograms/kg daily for 5 days

Contraindications

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  • Hypertrophic obstructive cardiomyopathy
  • Supraventricular arrhythmias due to accessory conducting pathways e.g. Wolff-Parkinson-White syndrome
  • Ventricular tachycardia or fibrillation
  • Intermittent complete heart block
  • Second degree atrioventricular block

Side Effects

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  • Stomach upset
  • Irregular heartbeat, heart block
  • Dizziness, headache, fatigue
  • Visual disturbances

Interactions

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  • Drugs that cause hypokalaemia e.g. acetazolamide. amphotericin B, furosemide, hydrochlorothiazide
  • Nifedipine (increased concentration of digoxin)
  • Quinine (increased concentration of digoxin)
  • Spironolactone (increased concentration of digoxin)
  • Verapamil (increased concentration of digoxin)

Patient Instructions

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  • Eat foods rich in potassium e.g. bananas to prevent risk of side effects

Pregnancy

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  • Can be used

Breastfeeding

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  • Can be used

⚠️ Caution

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  • Ensure patient has not been taking digoxin in the past 14 days before digitalizing because of risk of toxicity due to accumulation in the tissues; if they have been on digoxin, reduce the doses recommended above
  • Adjust maintenance dose based on kidney function
  • Use with caution in elderly since they are more prone to side effects
  • Avoid rapid IV administration to prevent nausea and increased risk of arrhythmias
  • Digoxin has a long half life and maintenance doses need to be given only once daily (although higher doses may be divided to prevent nausea)
  • Hypokalaemia increases the risk of digoxin toxicity; patient may need potassium-sparing diuretic or potassium supplements
  • If toxicity occurs, withdraw digoxin immediately and refer for urgent specialist treatment