DIGIFab

Appropriate Dosing Neutralizes Digoxin

DIGIFab Dosing Varies According to Clinical Condition1

  • DIGIFab dosing varies according to the patient’s clinical condition and the amount of
    digoxin to be neutralized.

For patients with a known or estimated amount of digoxin in the body,
use the DIGIFab dose calculator.

Acute Ingestion, Unknown Amount*

DIGIFab
Dose

digifab-dose-vial-image
  • 20 vials
  • (800 mg)
  • Monitor for volume overload in small (<20 kg) children
  • Initiate with 10 vials followed by an additional 10 vials, if needed, to avoid a febrile reaction

Acute Ingestion, Known Amount*

Calculate dose by entering amount of digoxin ingested

Total digoxin body load x 0.8/0.5 mg

Each vial of 40 mg purified digoxin-specific Fab
binds approximately 0.5 mg digoxin.

DIGIFab
Dose

  • # vials
  • # mg

Total body load for digoxin tablets is approximately equal to the amount ingested (in mg) x 0.8 (bioavailability of the tablet preparation).

Chronic Toxicity, Unknown Serum Digoxin Level

DIGIFab
Dose

  • Adults and children ≥20 kg
    6 vials (240 mg)
  • Infants and children <20 kg
    1 vial (40 mg)

Chronic Toxicity, Known Serum Digoxin Level

Calculate dose by entering steady-state serum digoxin concentration

Serum digoxin
concentration
x weight /100

Each vial of 40 mg purified digoxin-specific Fab
binds approximately 0.5 mg digoxin.

DIGIFab
Dose

  • # vials
  • # mg

*Suicidal ingestion may involve more than one drug. Toxic effects of other drugs or poisons should not be overlooked.

  • The reconstituted product should be used promptly. Unused product may be stored under refrigeration at 2° to 8°C (36° to 46°F) for up to 4 hours.

For complete dosing information, please see the full Prescribing Information.

General Precautions1

  • Serious digoxin toxicity can cause hyperkalemia; administration of potassium supplements in these patients may be hazardous. After treatment with DIGIFab, serum potassium concentration may decrease rapidly and must be monitored frequently, especially during the first several hours of administration.
  • The clinical condition of patients with poor cardiac function may deteriorate secondary to the withdrawal of the inotropic action of digoxin by DIGIFab. If needed, additional support can be provided by using other intravenous inotropes such as dopamine, dobutamine, or vasodilators.
  • Care must be taken not to aggravate digoxin-induced rhythm disturbances. Restoration of digoxin therapy should be postponed, if possible, until Fab fragments have been eliminated from the body, which may require several days; patients with impaired renal function may require 1 week or longer.

References

  1. DIGIFab Digoxin Immune Fab (ovine) [package insert]. West Conshohocken, PA: BTG International Inc.; 2017.
  2. Dart RC, Goldfrank LR, Erstad BL, et al. Expert consensus guidelines for stocking of antidotes in hospitals that provide emergency care. Ann Emerg Med. 2018;71(3):314-325.

INDICATIONS AND USAGE

DIGIFab is indicated for the treatment of patients with life-threatening or potentially life-threatening digoxin toxicity or overdose, including:

  • Known suicidal or accidental consumption of fatal doses of digoxin: 10 mg or more of digoxin in healthy adults, or 4 mg (or more than 0.1 mg/kg) in healthy children, or ingestion of an amount that can cause steady state serum concentrations of ≥10 ng/mL;
  • Chronic ingestions causing steady-state serum digoxin concentrations >6 ng/mL in adults or 4 ng/mL in children;
  • Manifestations of life-threatening toxicity of digoxin overdose such as severe ventricular arrhythmias, progressive bradycardia, and second or third degree heart block not responsive to atropine, serum potassium levels exceeding 5.5 mEq/L in adults or 6 mEq/L in children with rapidly progressive signs and symptoms of digoxin toxicity.

IMPORTANT SAFETY INFORMATION

Warnings and Precautions

General

Suicidal ingestion may result from more than one drug. Consider toxic effects of other drugs or poisons in cases where signs and symptoms of digitalis toxicity are not relieved by administration of DIGIFab.

Rapid drop in serum potassium concentration may occur after treatment. Monitor frequently.

Patients with poor cardiac function may deteriorate secondary to the withdrawal of the inotropic action of digoxin by DIGIFab. Monitor frequently and provide additional inotropic support if needed. Postpone re-digitalization, if possible, until the Fab fragments have been eliminated; this may require several days or a week or longer in patients with impaired renal function.

Hypersensitivity Reactions

Anaphylaxis and hypersensitivity reactions are possible. Carefully monitor patients for signs and symptoms of an acute allergic reaction and if one occurs, stop the infusion and treat immediately with appropriate emergency medical care.

Patients with known allergies to sheep protein or those who have previously received intact ovine antibodies or Fab are particularly at risk for an anaphylactic reaction.

Do not administer DIGIFab to patients with a known history of hypersensitivity to papaya or papain unless the benefits outweigh the risks and appropriate management for anaphylactic reactions is readily available.

Use of DIGIFab in Renal Failure

The elimination half-life of DIGIFab in renal failure has not been clearly defined. Monitor patients with severe renal failure who receive DIGIFab for a prolonged period for possible recurrence of toxicity. Monitoring of free (unbound) digoxin concentrations after the administration may be appropriate.

Laboratory Tests

DIGIFab may interfere with digitalis immunoassay measurements. Thus, standard serum digoxin concentration measurements may be clinically misleading until the Fab fragments are eliminated from the body. This may take several days or a week or more in patients with markedly impaired renal function. If possible, obtain serum digoxin samples before DIGIFab administration to establish the level of serum digoxin at the time of diagnosis.

The total serum digoxin concentration may rise precipitously following administration of DIGIFab, but this will be almost entirely bound to the Fab fragment and not able to react with receptors in the body.

Adverse Reactions

The most common adverse reactions (>7%) related to DIGIFab administration are worsening congestive heart failure (13%), hypokalemia (13%) and worsening atrial fibrillation (7%).

Please see full Prescribing Information.