Core pharmacology

Class Group

Antidote

Legacy Cicm Level

Level 3

Indications Uses

- For treatment of acute and chronic digoxin overdose
- Treatment of toxicities of other cardiac glycosides: oleander, bufotoxin (cane toad), Chinese medicines

Chemical Pharmaceutics

Monoclonal antibody (mAB) FAB (Fragment antigen-binding) fragment from sheep immunized with digoxin derivative

Presentation

powder
contains 38-40mg of digoxin-specific Fab fragments (which binds approx. 0.5mg Digoxin)
reconstitute with sterile water

Main Action

Binds Digoxin Molecules

Mechanism of action

Binds excess digoxin or digitoxin molecules circulating in the blood
- Fab fragment-digoxin complex excreted by kidney - Net shifts the equilibrium away from binding of digoxin to receptors

Onset Peak Duration

Onset: 0-60min
Peak: 30-360min

Adverse Effects Toxicity

Anaphylaxis – rare
Digoxin Withdrawal: AF, heart failure, hypokalemia

Absorption

-

Protein binding

-

Volume of distribution

0.3 L/kg [DigiFab]
0.4 L/kg [Digibind]

Metabolism

Nil

Excretion

Urine

Half-life

Unbound: 11 hrs
Bound: 15-20 hrs

Route And Dose

IV

Empiric: 10vials of Fab fragments

Known dose, no level:
Total body load = Dose (in mg) x 0.8 (BA of digoxin)
Number of vials = TBL x 2

Known concentration:
No of vials = [(serum digoxin concentration in ng/mL) x (patient's weight in kg)]/ 100