2.1.1 Cardiac glycosides
|1st choice||Digoxin tablets 62.5micrograms, 125micrograms, 250micrograms; |
solution for infusion 250micrograms/ml
|Dose (orally): |
Rapid digitalisation (for atrial fibrillation or flutter), 0.75-1.5mg in divided doses over 24 hours; less urgent digitalisation, 250-500micrograms daily (higher dose may be divided)
Maintenance (for atrial fibrillation or flutter), 62.5-250 micrograms daily [doses >125micrograms rarely needed for maintenance]
Heart failure (for patients in sinus rhythm), 62.5-125 micrograms once daily
- Digoxin is not a first line drug. It is indicated for rate control in atrial fibrillation and symptomatic heart failure even in sinus rhythm; it has no role in the prophylaxis of paroxysmal atrial fibrillation.
- For urgent rate control in atrial fibrillation, a loading dose of digoxin may be given intravenously or orally. Intravenous digoxin is potentially hazardous and should be reserved for patients with a clear need for urgent digitalisation.
- Digoxin may be a useful adjunct to a beta-blocker for heart rate control but assessment of heart rate/rhythm is required and doses more than 125 micrograms in this setting are generally best avoided.
- Regular measurements of plasma digoxin concentrations are not usually required except to confirm toxic levels, or to check compliance. Blood should be taken 6 hours or more after the last dose of digoxin. Laboratories in NI offer a normal range. Refer to the UKMI Drug monitoring guidance for further information.
- There is no therapeutic dose response relationship for digoxin in heart failure. Increasing doses >250 micrograms just increases toxicity.
- If toxicity occurs, digoxin should be withdrawn; serious manifestations require urgent specialist management. For further information on the management of toxicity see Toxbase or contact UK National Poisons Information Service on 0844 892 0111.
- Digoxin should not be used in the treatment of patients with pre-excitation syndromes, e.g. Wolff-Parkinson-White Syndrome, unless specifically prescribed by a specialist.
- Loading and maintenance doses of digoxin should be adjusted according to renal function. Age, sex and weight need to be considered. A maintenance dose of ≤125 micrograms daily is adequate in most patients. A lower maintenance dose (i.e. 62.5 micrograms daily) is often adequate in older patients, in patients with renal failure and in patients taking potentiating therapy – See NRLS: Preventing fatalities from medication loading doses for further information.
- Digoxin should be used with particular caution in the elderly and patients with renal impairment
- Hypokalaemia predisposes to digoxin toxicity. Care should be taken to monitor the electrolytes when prescribing diuretics. Consider use of appropriate potassium-sparing diuretics, or combination with ACE inhibitor/ARB as appropriate.