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Digoxin - Loading Dose Guide (Adults) 

 

Digoxin – Loading Dose Guide (Adults)

When to use IV loading

The intravenous route should be reserved for use in patients requiring urgent digitalisation for supraventricular arrhythmias (atrial fibrillation or flutter), or if patients are NBM or vomiting. ( Oral is the prefered route )

Check the drug history

Digoxin-induced cardiac toxicity may resemble the presenting cardiac abnormality. Therefore any patient presenting with a drug history of digoxin will require measurement of a plasma level prior to receiving additional digoxin.

IV loading dose

500 to 1000 micrograms IV (0.5 – 1mg) in 50-100ml sodium chloride 0.9% or 5% glucose over at least 2 hours.

Usual practice is to give 500 micrograms over 1-2 hours repeating with a 500 microgram dose after 6 hours if necessary.

Administer using a volumetric pump or syringe pump.

Oral loading dose

For atrial fibrillation or flutter – 500 micrograms PO then a further 500 micrograms 6 hours later.

(NB: Prescribe in once only section of drug chart).

Then assess clinically and prescribe maintenance dose if indicated.

Warning

The loading dose may need to be reduced if digoxin or another cardiac glycoside has been given in the preceding two weeks.

Oral maintenance dose

Revert to oral therapy as soon as possible.

Usual range is 125 - 250 micrograms OM (atrial fibrillation or flutter).

62.5 micrograms – 125 micrograms OM (heart failure in sinus rhythm).

(Elderly more susceptible to toxicity maximum 125 micrograms – NB renally excreted).

Bioavailability

125 microgram tablet is bioequivalent to 100 microgram elixir and to 100 microgram injection.

Maximum IV rate of administration

The IV dose may be given over 10 or 20 minutes if clinically justified ideally by central route.

Reasons to check level

Routine levels are not recommended.

Renal impairment, lack of response, interacting medication started or stopped, symptoms of toxicity.

Ideal sampling time

At least 6 hours post IV dose.

At least 6 hours post PO dose, or pre-dose.

Therapeutic drug monitoring

Accepted therapeutic range = 0.8 – 2.0 micrograms per litre.

Adverse events

Nausea, vomiting, dizziness, diarrhoea, visual disturbances, arrhythmias – typically ventricular extrasystoles and atrial tachycardia with varying AV block, sinus bradycardia, confusion.

Monitoring

Monitor ECG, heart rate and blood pressure.

Cardiac side-effects of digoxin are enhanced by acidosis, hypokalemia, hypomagnesaemia, hypercalcaemia, hypoxia and hypothyroidism.

Major factors influencing serum levels

This is not an exhaustive list. Refer to the BNF or Ward Pharmacist.


Document Owner Jan Jarman 
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