digoxin immune FAB (Antidote) (Rx)

Frequency Not Defined

Effects (due to w/d of digitalis) include exacerbation of HF, rapid ventricular response in patients with a.fib; posteral hypotension

Falsely increases digoxin concentrations

Hypokalemia

Loss of disease control

Phlebitis

Fever, May occur with doses above 10 vials

Allergic reactions

Serum sickness

Contraindications

None listed by the manufacturer

Cautions

Serum digoxin levels rise after digibind treatment - do not use serum levels to guide continuing treatment

Suicidal ingestion may result from more than one drug; toxic effects of other drugs or poisons should not be overlooked, especially in cases where signs and symptoms of digitalis toxicity are not relieved by administration of this medication

Rapid drop in serum potassium concentration may occur after treatment with this medication; monitor frequently, especially after first several hours of administration

Renal failure

• The elimination half-life of this medication in renal failure has not been clearly defined; monitor patients with severe renal failure who receive this medication for digitalis toxicity for a prolonged period for possible recurrence of toxicity
• Monitoring of free (unbound) digoxin concentrations after the administration may be appropriate in order to establish recrudescent toxicity in renal failure patients

Cardiac function

• Patients with poor cardiac function may deteriorate secondary to withdrawal of inotropic action of digoxin by this medication; if needed, provide additional support by using other intravenous inotropes such as dopamine, dobutamine or vasodilators; however, take additional care not to aggravate digitalis-induced rhythm disturbances
• Postpone re-digitalization, if possible, until the Fab fragments have been eliminated from the body, which may require several days, and patients with impaired renal function may require a week or longer

Hypersensitivity reactions

• Anaphylaxis and hypersensitivity reactions are possible; carefully monitor all for signs and symptoms of an acute allergic reaction (eg, urticaria, pruritus, erythema, angioedema, bronchospasm with wheezing or cough, stridor, laryngeal edema, hypotension, tachycardia) and treat immediately with appropriate emergency medical care (eg, oxygen, diphenhydramine, corticosteroids, volume expansion, and airway management), if one occurs
• If an anaphylactic reaction occurs during infusion, terminate drug administration at once and administer appropriate treatment; balance the need for epinephrine against potential risk in the setting of digitalis toxicity
• Patients with known allergies to sheep protein are particularly at risk for an anaphylactic reaction, as are individuals who have previously received intact ovine antibodies or ovine Fab
• Do not administer this drug to patients with a known history of hypersensitivity to papaya or papain unless the benefits outweigh risks and appropriate management for anaphylactic reactions is readily available
• Prior treatment with digoxin-specific ovine immune Fab carries a theoretical risk of sensitization to ovine serum protein and possible diminution of efficacy due to presence of human antibodies against ovine Fab
• To date, there have been no clinical reports of human anti-ovine immunoglobulin antibodies causing a reduction in binding of ovine digoxin immune Fab or neutralization response to ovine digoxin immune Fab

Pregnancy

Animal reproduction studies have not been conducted with this medication; not known whether therapy can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity; only administer to a pregnant woman if clinically needed

Lactation

Not known whether the drug is excreted in human breast milk

Because many drugs are excreted in human milk, exercise caution when administering to a nursing woman; administer to nursing mothers only if clinically needed

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

Mechanism of Action

Antibody binds digoxin or other cardiac glycosides and it is then excreted by the kidneys and removed from the body

Pharmacokinetics

Onset of action: ≤ 30 min (observed improvement)

Vd: 0.3 L/kg

Half-life elimination: 15-20 hr (prolonged in renal impairment)

Excretion: Urine (amounts undetectable within 5-7 days)

IV Preparation

Reconstitute with 4 mL SWI to obtain a 9.5 mg/mL Digibind solution or 10 mg/mL DigiFab soln

For infusion further dilute with NS to desired volume

If very small doses are necessary (<3 mg), may dilute with NS to 1 mg/mL

IV Administration

Infuse over 15-30 min

Digibind is administered using 0.22 micron inline filter; DigiFab should NOT be administered through filter

May be given as rapid IVP if cardiac arrest is imminent (generally not recommended due to increased adverse reactions)