Digoxin-specific antibody fragments (DigiFab and Digibind) are antigen-binding fragments derived from sheep immunoglobulins.
They act as a highly effective, first-line antidote for life-threatening digoxin or digitoxin toxicity.
The Fab fragments bind to free digoxin in the extracellular space with a higher affinity than the body’s Na⁺ / K⁺ ATPase receptors, pulling digoxin away from tissue and prompting renal elimination of the antibody-drug complex.
They are used for hemodynamically unstable patients, those with life-threatening tachy-bradyarrhythmias, or when serum potassium exceeds 6 mmol/L.
Standard Dosing: Each 38 mg or 40 mg vial binds approximately 0.5 mg of digoxin.
Administration & Monitoring
Delivery: Administered intravenously, typically over 15–30 minutes, or as a direct IV push in cases of cardiac arrest.
When the antidote is given, serum potassium may drop rapidly as digoxin shifts out of cells.
Severe rebound hypokalemia can occur and requires close monitoring.
Routine serum digoxin tests may yield falsely elevated or unreliable results after administration unless free digoxin” concentration assays are used.