Cardiac Glycoside Pregnancy: Use in pregnancy is not contraindicated, although dosage may be less predictable and some women require increased dosage. Use only when expected clinical benefit to the mother outweighs possible risk to the foetus. Breast-feeding is not contraindicated (quantities in milk are minute).

Digoxin

Brand names: Lanoxin

Digoxin is a cardiac glycoside used for rate control in atrial fibrillation and in heart failure; in older people its narrow therapeutic index and reliance on renal clearance make toxicity a key concern.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Elderly: as for adults but the possibility of reduced renal function and lower lean body mass should be taken into account; reduce and adjust the dose to prevent elevated serum digoxin levels and toxicity. Most heart-failure patients maintained on 125 to 250 micrograms (0.125-0.25 mg) daily; a dose of 62.5 micrograms (0.0625 mg) daily or less may suffice in increased sensitivity.

Route: Oral

Frequency: Maintenance once daily; loading (if used) in divided doses six hours apart

Max: Rapid oral loading up to 1500 micrograms (1.5 mg); elderly doses generally reduced due to toxicity risk

Dose must be tailored individually to age, lean body weight and renal function. In the elderly there is greater risk of toxicity, so where loading is used the oral loading dose should be given in divided doses six hours apart (approximately half the total dose as the first dose), assessing clinical response before each additional dose, rather than as a single rapid load. Serum digoxin levels should be checked regularly and hypokalaemia should be avoided. Rapid oral loading (adults/over 10 years) is 750-1500 micrograms as a single dose; slow oral loading 250-750 micrograms daily for one week. Maintenance based on percentage of peak body stores lost daily (daily loss % = 14 + creatinine clearance/5). If cardiac glycosides taken in preceding two weeks, reduce initial dose. When switching from oral to IV, reduce the dose by approximately 33%.

Dose adjustments

Renal

In the elderly, reduced renal function and lower lean body mass should be taken into account; reduce and adjust dose to the changed pharmacokinetics. Reconsider dosing if renal clearance is reduced; consider reduction in both initial and maintenance doses.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Intermittent complete heart block or second degree AV block, especially with history of Stokes-Adams attacks
Arrhythmias caused by cardiac glycoside intoxication
Supraventricular arrhythmias associated with an accessory AV pathway (e.g. Wolff-Parkinson-White syndrome)
Ventricular tachycardia or ventricular fibrillation
Hypertrophic obstructive cardiomyopathy (unless concomitant atrial fibrillation and heart failure, with caution)
Hypersensitivity to the active substance, other digitalis glycosides or any excipient

Side effects

Cardiac: arrhythmia, conduction disorder, bigeminy, trigeminy, PR prolongation, sinus bradycardia (common)
Gastrointestinal: nausea, vomiting, diarrhoea (common)
Nervous system: dizziness (common); headache (very rare)
Eye: visual impairment - blurred vision or xanthopsia (common)
Skin rash (common); gynaecomastia with long-term use (very rare)

Interactions

P-glycoprotein inducers/inhibitors (alter digoxin pharmacokinetics)
Amiodarone (digoxin serum concentration increased ~70%; reduce digoxin dose ~30-50%)
Captopril (digoxin serum concentration increased ~58%)
Clarithromycin (digoxin AUC increased ~70%)
Drugs affecting serum electrolytes/potassium (hypokalaemia predisposes to toxicity)

Clinical monograph

How it works

It inhibits the myocardial sodium-potassium ATPase, raising intracellular calcium to increase contractility, and enhances vagal tone to slow atrioventricular conduction.

Prescribing in practice

Older patients are highly susceptible to toxicity because of declining renal function and low body mass, so use lower doses, account for renal impairment, and recognise that hypokalaemia, hypomagnesaemia and hypercalcaemia potentiate toxicity.
Many interacting drugs (including amiodarone, verapamil, diuretics and macrolides) raise levels or precipitate toxicity, so review co-prescriptions carefully.
Toxicity may present atypically as confusion, nausea, anorexia, visual disturbance or new arrhythmia.

Monitoring

Monitor renal function and electrolytes (particularly potassium), heart rate and clinical response, with digoxin level measurement guided by symptoms and taken at an appropriate interval after dosing.

Counselling the patient

Report nausea, loss of appetite, confusion, visual changes or palpitations, which can signal toxicity.
Do not stop or change the dose without advice, and keep regular blood tests.
Tell clinicians about all new medicines, as many interact with digoxin.

Evidence & guidelines

Long-standing trial and registry data support digoxin for rate control and symptom relief, while pharmacokinetic principles underpin cautious dosing and monitoring in older patients with reduced renal reserve.

Reference: NICE NG106 (Chronic Heart Failure); ESC AF Guidelines 2020; STOPP/START v3; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways