Dosing regimen for digoxin-specific antibody (Fab) fragments in patients with digoxin toxicity
- Michael Levine, MD
Michael Levine, MD
- Assistant Professor of Emergency Medicine
- Department of Emergency Medicine, section of Medical Toxicology
- University of Southern California
- Ayrn O'Connor, MD
Ayrn O'Connor, MD
- Clinical Associate Professor of Emergency Medicine
- University of Arizona College of Medicine
- Section Editors
- Stephen J Traub, MD
Stephen J Traub, MD
- Section Editor — Toxicology
- Associate Professor of Emergency Medicine
- Mayo Medical School
- Michele M Burns, MD, MPH
Michele M Burns, MD, MPH
- Section Editor — Pediatric Toxicology
- Assistant Professor of Pediatrics
- Harvard Medical School
Digoxin-specific antibody (Fab) fragments are the definitive treatment for patients with severe digitalis poisoning.
Prior to the advent of digoxin-specific antibodies, treatment for cardiac glycoside toxicity was largely supportive . In 1976, antibody fragments were first used successfully to treat patients . These antibodies are highly effective, safe, and widely used in clinical practice .
The dosing of digoxin-specific antibody (Fab) fragments based upon different clinical scenarios is discussed here. The indications for treatment with Fab fragments, the diagnosis and general management of digitalis poisoning, and the clinical use of digitalis are all reviewed separately. (See "Digitalis (cardiac glycoside) poisoning", section on 'Antidotal therapy with antibody (Fab) fragments' and "Use of digoxin in heart failure due to systolic dysfunction" and "Control of ventricular rate in atrial fibrillation: Pharmacologic therapy", section on 'Digoxin' and "Treatment with digoxin: Initial dosing, monitoring, and dose modification".)
WHAT ARE FAB FRAGMENTS?
Digoxin-specific antibody (Fab) fragments are purified preparations consisting of the Fab portion of IgG antidigoxin antibodies derived from immunized sheep. These fragments bind free digoxin, thereby forming digoxin-immune fragment complexes. As the level of free digoxin in plasma falls, the resulting concentration gradient facilitates dissociation of digoxin from the sodium-potassium ATPase.
Digoxin-immune fragment complexes are renally excreted. Because the size of the digoxin-immune complex molecule is large, hemodialysis is not an effective means of removal.
- Bayer MJ. Recognition and management of digitalis intoxication: implications for emergency medicine. Am J Emerg Med 1991; 9:29.
- Smith TW, Haber E, Yeatman L, Butler VP Jr. Reversal of advanced digoxin intoxication with Fab fragments of digoxin-specific antibodies. N Engl J Med 1976; 294:797.
- Antman EM, Wenger TL, Butler VP Jr, 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.
- DigiFab® US FDA approved product information. US National Library of Medicine. www.dailymed.nlm.nih.gov (Accessed on May 10, 2010).
- DigiBind® US FDA approved product information. US National Library of Medicine. www.dailymed.nlm.nih.gov (Accessed on May 10, 2010).
- WHAT ARE FAB FRAGMENTS?
- CALCULATING THE DOSE
- Neither the digoxin level nor amount ingested is known
- Amount of digoxin ingested is known but concentration is unknown
- Steady state digoxin concentration is known
- Cardiac glycoside poisoning other than digoxin or digitoxin
- HOW TO ADMINISTER THE DRUG
- Basic guidelines
- Chronic toxicity without severe signs
- SUMMARY AND RECOMMENDATIONS