Who can administer
May be administered by registered competent doctor or nurse/midwife
Important information
- Once Digifab has been administered, there is no clinical benefit in measuring serum digoxin levels (as the level will represent both free and bound digoxin.)
- Therefore, it is important to monitor the cardiac status of the patient for at least 24 hours after administration for signs of recurrent toxicity (ref 1)
- Infusion related reactions or hypersensitivity reactions are possible - monitor closely for signs of allergic reaction. See Further Information
- Consultation with National Poisons Centre (NPIC) may be advisable in acute overdose situation or if clinical features persist despite treatment (ref 1)
- The onset of response is usually within 30 minutes
- See also Renal impairment below
- See 'Monitoring'overleaf
- Stored in fridge in ED with back-up stock in the pharmacy
Available preparations
Digifab 40mg vial
Reconstitution
Water for injection
4ml per 40mg vial
Infusion fluids
Sodium chloride 0.9%
Methods of intravenous administration
Intermittent intravenous infusion (preferred route)
- Dilute required dose with any convenient volume of infusion fluid (suggested volume 100ml (ref 2)) and administer over 30 minutes
- If an infusion related reaction occurs, the infusion should be stopped and the patient treated. Consider restarting the infusion at a slower rate (ref 1,2)
- The residual volume in the infusion line must be flushed through at the same rate to avoid significant underdosing
Bolus intravenous injection
- If cardiac arrest is imminent Digifab may be given undiluted by rapid injection (ref 2)
- An increased incidence of allergic reactions may be expected using a bolus intravenous injection
Dose in adults
A: Cardiac arrest due to digoxin toxicity:
- Urgently administer Digifab as an IV bolus
- Weight greater than 40kg: give 5 vials (200 mg)
- Further doses may be required if an adequate clinical response is not seen after 30 minutes
B: Other indications
- e.g.acute digoxin overdose on top of usual therapy, acute overdose in digoxin-naive patient, digoxin toxicity from chronic therapy - the following calculations can be used to work out the required dose
- Doses below are as per Toxbase, rather than the SPC
- If clinical features persist despite treatment, discuss with Posions centre
The dose depends on the clinical situation and on whether plasma digoxin concentration is available (ref 1)
- B1. When digoxin concentration is available (measured 6 hours after overdose/last dose, unless urgently indicated in patient with arrhythmia):
- Number of vials =
- {0.781 x serum digoxin concentration (nanomol/L) x weight (kg)} /200
- Round up to the nearest vial - for convenience, these doses have been worked out in table 1 below
| Table 1: Initial dose - when digoxin concentration is available |
- As most assay kits are not designed to measure values above 6.4nmol/L (5ng/ml),serum digoxin concentration reported may be inaccurate at high levels
- Important: If clinical features persist despite initial dose, then discuss with NPIC (01) 809 2566 or 01 837 9964
|
|
Example, a patient who weighs 80kg, with a digoxin level of 5.12nanomoL/L- should receive an initial dose of 2 vials
|
| Patient weight (kg) |
Serum digoxin concentration (nanomol/L) |
| |
2.56 |
5.12 |
10.24 |
15.36 |
20.48 |
25.6 |
| 40 |
1 vial |
1 vial |
2 vials |
3 vials |
4 vials |
4 vials |
| 60 |
1 vial |
2 vials |
3 vials |
4 vials |
5 vials |
6 vials |
| 70 |
1 vial |
2 vials |
3 vials |
5 vials |
6 vials |
7 vials |
| 80 |
1 vial |
2 vials |
4 vials |
5 vials |
7 vials |
8 vials |
| 100 |
1 vial |
2 vials |
4 vials |
6 vials |
8 vials |
10 vials |
- B2. When only ingested dose is available (overdose situation):
- Number of vials = Amount of digoxin ingested (mg) x 0.8
- Round up to the nearest vial
- If clinical features persist despite initial dose, then discuss with NPIC (01) 809 2566 or 01 837 9964
- Example: if a patient ingested twenty-five tablets of the 0.25mg strength, as an acute single ingestion, (0.25mg x 25 tablets x 0.8) = 5 vials initially
Renal impairment
- It may be expected that excretion of the Fab-digoxin levels complexes from the body is slowed in the presence of renal impairment, and that digoxin may be released after some days from retained Fab-digoxin complexes
General information
- Erroneous dosage calculations may result from inaccurate estimates of the amount of digoxin ingested or absorbed, or from non steady-state serum digoxin concentrations
- If after several hours toxicity has not been adequately reversed or appears to recur, re-administration of Digifab at a dose guided by clinical judgement may be required
- If there is no response to an adequate dose of Digifab, the diagnosis of digitalis toxicity should be questioned
Monitoring
- Patients should have continuous ECG monitoring during and for at least 24 hours after administration of Digifab
- Monitor temperature, potassium, blood pressure during and after administration
Further information
- Digoxin serum levels are reported in UHG as nanomol/l. Toxbase refers to levels in nanogram/ml
- To convert nanomol/L to nanogram/ml multiply nanomol/L by 0.781. For example 2.5 nanomol/L = 1.95nanogram/ml
- The likelihood of hypersensitivity reactions is higher in patients who are allergic to sheep-derived proteins, or to papain, an extract of the papaya fruit, dust mites or latex
- Digoxin antidote has previously been used in two doses: one calculated to neutralise all the digoxin load ('full neutralisation' dose (FND)) and one calculated to neutralise only half of it ('half neutralisation' dose)
- Recent evidence indicates that the 'half neutralisation' dose is adequate for most patients.
- The dosage information in this monograph is taken from Toxbase. It recommends the use of 'Half-neutralisation doses'.
Storage
- Store at 2 to 80C
- Do not freeze
References
Package insert and SPC June 2024
1: Toxbase, downloaded 10/04/2025
2:Injectable Medicines Administration Guide Medusa downloaded 10/04/2025
Therapeutic classification
Antidote
