Sarah Taylor

• Digoxin is indicated for rate control in atrial fibrillation and symptomatic heart failure; it has no role in the prophylaxis of atrial fibrillation
  
• Heart failure may also be improved, even in patients in sinus rhythm, because of changes in the availability of intracellular calcium; this action is relatively unimportant, however, compared with the effects that can be achieved with diuretics and ACE inhibitors.
  
• For rapid rate control in atrial fibrillation, a loading dose of digoxin may be given intravenously or orally.
  
• The maintenance dose of cardiac glycoside can usually be determined by the ventricular rate at rest which should usually not be allowed to fall below 60 beats per minute.
  
• Regular monitoring of plasma digoxin concentrations is not usually required except to confirm toxic or sub-therapeutic levels, or to check compliance.
  
• Hypokalaemia predisposes to digoxin toxicity and care should be taken to avoid hypokalaemia. (e.g in patients taking digoxin and a diuretic). Hypokalaemia can be managed by giving a potassium-sparing diuretic or, if necessary potassium supplements
  
• The elderly are particularly susceptible to digoxin toxicity therefore, digoxin should be used with particular caution in these patients and those with renal impairment.
  
• Drugs such as amiodarone, quinidine, quinine, hydroxychloroquine may increase digoxin levels.
  
• The elixir has slightly increased bioavailabilty therefore doses given as tablets are not equivalent. A tablet dose of 62.5 micrograms is approximately equivalent to 50 micrograms when given as the elixir ( 50micrograms/ml). Check blood levels if changing formulations.

Formulary Choice - Digoxin

Starting Dose
Rapid digitalisation Less urgent digitalisation Maintenance
1-1.5mg in divided doses over 24 hours 250-500 micrograms daily 62.5-500 micrograms daily depending on renal function and heart rate (usual range 125-250 micrograms)

Monitoring
Regular measurements of plasma digoxin concentrations are not usually required except to confirm toxic or sub-therapeutic levels, or to check compliance. For plasma concentration monitoring, blood should be taken 7-14 days after a dose change to ensure steady state conditions and at least 6 hours after a dose.
Renal function, U&Es ( particularly potassium) and heart rate should also be monitored

ADVICE TO PATIENTS

The following advice to patients is also available as a printable PDF document

1. These tablets are help the heart to beat strongly and regularly
2. It is important to take these tablets regularly. Try to take them at the same time each day. Do not stop taking tem without speaking to your doctor first.
3. Avoid taking indigestion remedies for at least one hour before and after taking your digoxin tablets. They can reduce the amount of digoxin your body absorbs and make it less effective
4. You should tell any doctor, dentist, pharmacist or nurses that you take this medicine. Some medicines that you can buy should not be taken with this medicine. Ask your pharmacist or doctor for advice.
5. Like all medicines, these tablets can have some unwanted effects. If you feel sick, vomit, lose your appetite, or have palpitations or blurred vision, tell your doctor straight away.
6. You should read the information leaflet that you have been given with your medicines carefully. This contains full information about side effects etc. If you have any questions or concerns about your medicines, you should discuss them with your doctor or pharmacist. Patient information leaflets are available at www.emc.vhn.net/public/

Based on "Advice Tips" published in the Pharmaceutical journal by Pharmacy Practice Consultants.
Available at www.pharmj.com/noticeboard/tips/patients/index.html