Indications
Digoxin is a heart medicine used to treat heart failure (when the heart does not pump strongly enough) and to control a fast heart rate in certain rhythm problems, especially atrial fibrillation and atrial flutter.
How It Works
Digoxin blocks a pump in heart muscle cells (the sodium-potassium pump), which leaves more calcium inside the cells and makes each heartbeat stronger. It also slows the passage of electrical signals through the heart’s AV node, so the heart beats more slowly and regularly when the upper chambers are beating too fast.
Dosage and Administration
Digoxin must be taken exactly as prescribed, because the gap between a helpful dose and a harmful dose is small. Doctors often start with a loading dose and then give a daily maintenance dose, commonly 62.5 to 250 micrograms once a day, adjusted for age, weight, kidney function and blood levels. Take it at the same time each day. Do not double a missed dose. Injections are given by a doctor or nurse in hospital.
Interactions
- These can raise digoxin levels and cause toxicity: Amiodarone, Dronedarone, Verapamil, Diltiazem, Quinidine, Propafenone, Clarithromycin, Erythromycin, Itraconazole, Ciclosporin, Spironolactone and Carvedilol.
- Diuretics such as Furosemide and Hydrochlorothiazide, corticosteroids and laxative overuse can lower potassium or magnesium, making toxicity more likely.
- Antacids, Cholestyramine, Sulfasalazine, Rifampicin and St. John’s Wort can lower digoxin levels.
- Beta blockers and calcium channel blockers add to the slowing of the heart rate.
Contraindications
- Certain heart rhythm problems: second or third degree heart block without a pacemaker, ventricular tachycardia or fibrillation, and Wolff-Parkinson-White syndrome with atrial fibrillation.
- Hypertrophic obstructive cardiomyopathy, unless a specialist advises.
- Known digoxin toxicity or allergy to digoxin.
Side Effects
Possible effects include nausea, loss of appetite, diarrhoea, dizziness, tiredness, headache and, with long-term use, breast enlargement in men. Many side effects are signs that the level is too high.
Get urgent medical help if you have signs of digoxin toxicity: repeated vomiting, severe loss of appetite, confusion, blurred vision or seeing yellow or green tints or halos around lights, a very slow, fast or irregular heartbeat, palpitations, fainting or severe weakness.
Pregnancy and Lactation
Digoxin may be used in pregnancy when a doctor considers it necessary; doses and levels need close monitoring. Small amounts pass into breast milk, and it is generally considered compatible with breastfeeding under medical supervision.
Precautions and Warnings
- You will need regular blood tests for digoxin level, potassium, magnesium and kidney function.
- Older people and those with kidney disease or thyroid problems need lower doses.
- Tell every doctor, dentist and pharmacist that you take digoxin before starting any new medicine or herbal product.
- Do not switch between brands without your doctor’s advice.
Overdose
Digoxin overdose is a medical emergency that can cause dangerous heart rhythms, high potassium, vomiting and confusion. Get emergency help at once. An antidote (digoxin-specific antibody) is available in hospital.
Therapeutic Class
Cardiac glycoside (antiarrhythmic and inotropic agent).
Storage
Store below 30°C in a dry place, away from light. Keep injections as directed on the pack. Keep out of the reach of children, as even a few tablets can be very dangerous to a child.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.