Fragments

(BAN, rINN)

💊 Chemical information

Digoxin Immune Fab (Ovine); F(ab); Fragmentos de anticuerpos específicos antidigoxina.
ATC — V03AB24.
ATC Vet — QV03AB24.

💊 Adverse Effects and Precautions

Allergic reactions to digoxin-specific antibody fragments have been reported rarely. Patients known to be allergic to sheep protein and patients who have previously received digoxin-specific antibody fragments are likely to be at greater risk of developing an allergic reaction. Blood pressure, ECG, and potassium concentrations should be monitored closely during and after use.

💊 Uses and Administration

Digoxin-specific antibody fragments are derived from antibodies produced in sheep immunised to digoxin. Digoxin has greater affinity for the antibodies than for tissue-binding sites, and the digoxin-antibody complex is then excreted in the urine. Digoxin-specific antibody fragments are generally restricted to the treatment of life-threatening digoxin or digitoxin intoxication in which conventional treatment is ineffective. Successful treatment of lanatoside C poisoning has also been reported. It is estimated that 38 mg of antibody fragments could bind about 500 micrograms of digoxin or digitoxin and the dose calculation is based on this estimate and the body-load of digoxin (based on the amount ingested or ideally from the steady-state plasma concentration). Administration is by intravenous infusion over a 30minute period. If cardiac arrest is imminent the dose may be given as a bolus. In the case of incomplete reversal or recurrence of toxicity a further dose can be given. In patients considered to be at high risk of an allergic response an intradermal or skin scratch test may be performed.
An initial response is usually seen within 30 minutes of the end of the infusion with a maximum response after 3 to 4 hours.4 The main causes of treatment failure or partial response are incorrect diagnosis of digitalis intoxication, inadequate dosage of antibody fragments, and use in patients already moribund.3,4 Few adverse reactions have been attributed to the use of digoxin-specific antibody fragments; a few cases of minor allergic reactions have been reported including erythema, facial swelling, urticaria, and rashes,2,4 but no anaphylactic reactions have been reported.1-4Haemodynamic status normally improves, but withdrawal of the inotropic support provided by digoxin may produce a decline in cardiac function in some patients. There may be dramatic reductions in plasma potassium concentrations. Treatment has been successful in patients with varying degrees of renal impairment.2,4,5 Elimination of the antibody fragmentdigoxin complex may be markedly delayed in severe renal impairment and prolonged monitoring may be required in such patients.6 Measurement of free serum-digoxin concentrations may be useful.7 Experience with digoxin-specific antibody fragments in a patient with chronic renal failure receiving haemodialysis has been reported.8 The patient had a good clinical response but haemodialysis did not remove the antibody fragment-digoxin complex. In patients with adequate renal function the half-life of the antibody fragment-digoxin complex has been reported2 to be about 16 to 20 hours although longer half-lives have been reported.9 It has been suggested10 that giving digoxin-specific antibody fragments by infusion over 7 hours, after an initial loading dose, could be useful in ensuring adequate antibody concentrations are maintained to bind digoxin as it is released from tissue stores over a prolonged period. Use of the antibody fragments has also been effective in children with severe digitalis intoxication.11 Digoxin-specific antibody fragments have also been used successfully in poisoning due to preparations containing toad venom,12 or due to common or yellow oleander.
1. Smith TW, et al. Treatment of life-threatening digitalis intoxication with digoxin-specific Fab antibody fragments: experience in 26 cases. N Engl J Med 1982; 307: 1357–62
2. Wenger TL, et al. Treatment of 63 severely digitalis-toxic patients with digoxin-specific antibody fragments. J Am Coll Cardiol 1985; 5: 118A–123A
3. Antman EM, et al. Treatment of 150 cases of life-threatening digitalis intoxication with digoxin-specific Fab antibody fragments: final report of a multicenter study. Circulation 1990; 81: 1744–52
4. Flanagan RJ, Jones AL. Fab antibody fragments: some applications in clinical toxicology. Drug Safety 2004; 27: 1115–33
5. Allen NM, et al. Clinical and pharmacokinetic profiles of digoxin immune Fab in four patients with renal impairment. DICP Ann Pharmacother 1991; 25: 1315–20
6. Ujhelyi MR, et al. Disposition of digoxin immune Fab in patients with kidney failure. Clin Pharmacol Ther 1993; 54: 388–94
7. Ujhelyi MR, Robert S. Pharmacokinetic aspects of digoxin-specific Fab therapy in the management of digitalis toxicity. Clin Pharmacokinet 1995; 28: 483–93
8. Clifton GD, et al. Free and total serum digoxin concentrations in a renal failure patient after treatment with digoxin immune Fab. Clin Pharm 1989; 8: 441–5
9. Gibb I, Parnham A. A star treatment for digoxin overdose? BMJ 1986; 293: 1171–2
10. Schaumann W, et al. Kinetics of the Fab fragments of digoxin antibodies and of bound digoxin in patients with severe digoxin intoxication. Eur J Clin Pharmacol 1986; 30: 527–33
11. Woolf AD, et al. The use of digoxin-specific Fab fragments for severe digitalis intoxication in children. N Engl J Med 1992; 326: 1739–44
12. Brubacher JR, et al. Treatment of toad venom poisoning with digoxin-specific Fab fragments. Chest 1996; 110: 1282–8.

💊 Preparations

Proprietary Preparations

Austral.: Digibind; Austria: Digitalis Antidot†; Belg.: Digitalis Antidot; Canad.: Digibind; Fr.: Digidot†; Ger.: Digitalis Antidot; Gr.: Digibind†; DigiFab; Hong Kong: Digitalis Antidote; Swed.: Digitalis Antidot; Switz.: Digitalis Antidot; UK: Digibind; USA: Digibind; DigiFab.
Published November 01, 2018.