Digoxin Intravenous for adults

Who can administer

INFUSION may be administered by registered competent doctor or nurse/midwife.

Bolus injection- Restricted see appendix 1

Important information

• Always prescribe the dose in micrograms
• For dose guidance for transferring patients from PO to IV therapy- see under 'Dose'
• See monitoring requirements
• Renal dose adjustments are required

Available preparations

Lanoxin 500 microgram per 2ml ampoule

Reconstitution

Already in solution

Draw up using a 5micron filter needle

Dilute further prior to administration

Infusion fluids

Sodium chloride 0.9% or Glucose 5%

Methods of intravenous administration

Intermittent intravenous infusion (using an electronically controlled infusion device) (preferred route)

• Add required dose to 100ml of infusion fluid. (ref 1)
• A 50ml infusion may be used if required (eg fluid restriction) but the residual volume in the infusion line must be flushed through at the same rate to avoid significant underdosing
• If loading with repeated fractions of small doses (e.g. 50%, 25%, 25%) the infusion may be given over 10 to 20 minutes.
• However, where large loading doses are required in emergencies (e.g. 750microgram to 1000microgram) a minimum infusion time of 2 hours is suggested (ref 1)
• If using a two hour infusion time, protect infusion solution from light

Slow intravenous injection (not generally recommended)

• Intravenous infusion is preferred but if essential digoxin may be administered by slow intravenous injection as follows:
• Bolus administration is more likely to cause adverse effects. Patients should be monitored closely for signs of digoxin toxicity; hypertension and reduced coronary flow (ref 1)
• Either dilute at least four fold (add 4ml to 1ml) with either Sodium chloride 0.9% or Glucose 5% and administer over 10 to 20 minutes(ref 1,3) OR
• If fluid-restricted: administer undiluted via a large vein or central line over at least 5 minutes (ref 3) (unlicensed)

Dose in adults

LOADING DOSE (for patients who have not been given cardiac glycosides within the previous two weeks)

• The normal loading dose is 500 to 1000 microgram (depending on age, lean body weight and renal function)
• This is usually given in three divided doses of 50%, 25%, 25%
• Each part of the dose should be given four to eight hours after the last
• Example: total dose required is 1000microgram:
  • Give 500micogram
  • Followed by 250microgram four hours later
  • Followed by a further 250microgram after a further four hours
• An assessment of clinical response should be performed before giving each additional dose

Urgent (emergency) loading required (ref 2)

• Give 750 to 1000 microgram over a minimum of 2 hours
• A reduced loading dose may be needed if the patient has received digoxin in the last 2 weeks

MAINTENANCE DOSE

• Where a patient is on oral digoxin, and a temporary switch to IV is indicated eg if a patient is unable to take oral digoxin, the intravenous dosage should be reduced by approximately 33% - for example, 250 micrograms tablet is approximately equivalent to 166 micrograms IV - round to 175 micrograms
• Monitor levels closely if switching between routes of administration

Renal impairment

Dose reductions required - contact pharmacy for advice

Monitoring

Telemetry monitoring during administration ^{(ref 5)}

Monitoring of levels

• At least 6 or more hours after the last dose to allow for redistribution

Therapeutic range

• Heart failure: Trough levels usually between 0.64 to 1.28 nanomols/L (0.5 to 1nanograms/ml)
• Other indications: Trough levels usually between 0.64 and 2.6 nanomol/L (0.5 to 2 nanograms/ml) (ref 4)
• However, toxicity may occur with lower digoxin serum concentrations. In deciding whether a patient's symptoms are due to digoxin, the clinical state together with the serum potassium level and thyroid function are important factors.

Further information

• Intramuscular injection is NOT RECOMMENDED, as it is painful and is associated with muscle necrosis
• An antidote (Digifab) is available for suspected digoxin toxicity

Storage

• Store below 25⁰C

References

SPC March 2020

1. Medusa Injectable Medicines Guide downloaded 03/2022

2: BNF 83

3: Minimum Infusion Volumes for Fluid Restricted Critically Ill Patients 4rd Ed

4. Medicines Complete - assessed online 03/2022

5: Local guidelines, email on file, January 2017

Therapeutic classification

Cardiac glycosides