DIGOXIN IMMUNE FAB (OVINE)

DIGOXIN IMMUNE FAB (OVINE)
(di-jox'in)
Digibind, DigiFab
Classifications: antidote;
Therapeutic: antidote
Pregnancy Category: C

Availability

38 mg, 40 mg vial

Action

Purified fragments of antibodies specific for digoxin (but also effective for digitoxin) produced in sheep. Use of fragments of antidigoxin antibodies (Fab) instead of whole antibody molecules permits more extensive and faster distribution to serum and toxic cellular sites. Fab acts by selectively complexing with circulating digoxin or digitoxin, thereby preventing drug from binding at receptor sites; the complex is then eliminated in urine.

Therapeutic Effect

Digoxin immune Fab is a protein that consists of antibody fragments, which are used as an antidote for digitalis toxicity.

Uses

Treatment of potentially life-threatening digoxin or digitoxin intoxication in carefully selected patients.

Contraindications

Hypersensitivity to sheep products; renal or cardiac failure; pregnancy (category C).

Cautious Use

Prior treatment with sheep antibodies or ovine Fab fragments; mannitol hypersensitivity; history of allergies; impaired renal function or renal failure; elderly; lactation.

Route & Dosage

Serious Digoxin Toxicity Secondary to Overdose
Adult/Child: IV Dosages vary according to amount of digoxin to be neutralized; dosages are based on total body load or steady state serum digoxin concentrations (see package insert); some patients may require a second dose after several hours

Administration

Intravenous

PREPARE: Direct: Dilute each vial with 4 mL of sterile water for injection to yield 9.5 mg/mL for Digibind and 10 mg/mL for DigiFab; mix gently. IV Infusion: Dilute further with any volume of NS compatible with cardiac status. For those receiving less than 3 mg, further dilute to a concentration of 1 mg/mL by adding an additional 34 mL of NS to Digiband or 36 mL of NS to DigiFab.

ADMINISTER: Direct: Give undiluted bolus only if cardiac arrest is imminent. IV Infusion: Give IV infusion over 30 min, preferably through a 0.22-micron membrane filter. ??For administration to infants: Reconstitute for direct IV and administer with a tuberculin syringe. For small doses (e.g., 2 mg or less), dilute the reconstituted 40 mg vial with 36 mL of NS to yield 1 mg/mL. Closely monitor for fluid overload.

Use reconstituted solutions promptly or refrigerated at 2°–8° C (36°–46° F) for up to 4 h.

Adverse Effects (≥1%)

Adverse reactions associated with use of digoxin immune Fab are related primarily to the effects of digitalis withdrawal on the heart (see Nursing Implications). Allergic reactions have been reported rarely. Hypokalemia.

Diagnostic Test Interference

Digoxin immune Fab may interfere with serum digoxin determinations by immunoassay tests.

Interactions

Drug: Not established.

Pharmacokinetics

Onset: <1 min after IV administration. Elimination: Excreted in urine over 5–7 d. Half-Life: 14–20 h.

Nursing Implications

Assessment & Drug Effects

Perform skin testing for allergy prior to administration of immune Fab, particularly in patients with history of allergy or who have had previous therapy with immune Fab.
Keep emergency equipment and drugs immediately available before skin testing is done or first dose is given and until patient is out of danger.
Monitor for therapeutic effectiveness: Reflected in improvement in cardiac rhythm abnormalities, mental orientation and other neurologic symptoms, and GI and visual disturbances. S&S of reversal of digitalis toxicity occurs in 15–60 min in adults and usually within minutes in children.
Baseline and frequent vital signs and EGG during administration.
Lab tests: Baseline and periodic serum potassium and serum digoxin; serum digoxin or digitoxin concentration (this measurement will not be accurate for at least 5–7 d after therapy begins because of test interference by immune Fab).
Note: Serum potassium is particularly critical during first several hours following administration of immune Fab. Monitor closely.
Monitor closely: Cardiac status may deteriorate as inotropic action of digitalis is withdrawn by action of immune Fab. CHF, arrhythmias, increase in heart rate, and hypokalemia can occur.
Make sure serum digoxin levels and ECG readings are obtained for at least 2–3 wk.

Patient & Family Education

Tell your prescriber or health care professional about all other medications you are taking, including non-prescription medications, nutritional supplements, or herbal products. Include information about whether you frequently consume drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way this medicine works.
Check with your prescriber before stopping or starting any of your medicines.
Inform the prescriber if you have any of the following conditions: kidney disease; an unusual or allergic reaction to sheep proteins, mannitol other medicines, foods, dyes, or preservatives.
Report to a prescriber if you are pregnant.
Report to prescriber if you are breast-feeding.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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