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digoxin immune Fab (Digibind)
Tradename: Digibind.
Indications:
1) adjunctive therapy for life-threatening or potentially life-threatening digoxin or digitoxin toxicity
2) oleander toxicity
Dosage:
1) Digoxin toxicity 2-20 vials IV over 15-30 minutes
2) 40 mg of Digibind binds approximately 0.6 mg of glycoside
Injection: 38-40 mg/vial.
TBL: total body load of digoxin in mg
C: measured serum concentration in ng/mL
TBL = C x 5.6 x body weight (kg)/1000
Digibind dose (mg) = TBL x 76
Digibind dose (vials) = C (ng/mL) x weight (kg)/100
Pharmacokinetics:
1) peak concentrations occur at the completion of infusion
2) free (unbound) glycoside concentrations decline within 15-30 minutes
3) measure serum concentrations of digoxin may increase 10-20 fold, but don't correlated with free dixogin
4) eliminated in the urine
5) elimination 1/2life is 12-20 hours
Adverse effects:
1) hyperkalemia
a) due to extracellular shifts of K+
b) patient may actually be total body K+ depleted
c) K+ levels return to normal in 4-6 hours
2) allergic reactions
Drug interactions:
- digoxin: do not attempt to redigitalize for 2-3 days, or for 5-7 days if evidence of renal insufficiency
Mechanism of action:
1) high-affinity, specific antigen-binding fragments bind free (unbound) digoxin or digitoxin
2) blocks & reverses inhibition of Na+/K+ ATPase
General
antidote
Fab fragment
Properties
INHIBITS: digoxin
MISC-INFO: elimination route KIDNEY
1/2life 12-20 HOURS
pregnancy-category C
safety in lactation ?
References
- The Pharmacological Basis of Therapeutics, 9th ed.
Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- Drug Information & Medication Formulary, Veterans Affairs,
Central California Health Care System, 1st ed., Ravnan et al
eds, 1998
- Kaiser Permanente Northern California Regional Drug
Formulary, 1998
- Department of Veterans Affairs, VA National Formulary