Treatment of chronically digoxin-poisoned patients with a newer digoxin immune fab--a retrospective study.
BACKGROUND
Digoxin is used in the treatment of patients with cardiac dysfunction, though toxicity sometimes results from the use of this medication. In 1986, the US Food and Drug Administration (FDA) approved a digoxin immune Fab for the treatment of such patients. In 2001, the FDA approved a newer digoxin immune Fab, a digoxin-specific antibody (DSAb) known as DigiFab (Protherics Inc, Brentwood, Tennessee), though minimal literature exists on the clinical effects of this DSAb.


OBJECTIVE
To characterize a cohort of patients presenting with chronic digoxin toxicity and to describe the clinical course of these patients with the use of DSAb.


METHODS
A retrospective study included patients with life-threatening cardiotoxicity and serum digoxin level greater than 2 ng/mL who were treated at two US hospitals from 2003 to 2006. Trained investigators abstracted data from patients' medical records and assessed changes in clinical and laboratory parameters at regular intervals (0-4, >4-12, >12-24, and >24-72 hours) after treatment with DSAb. An expert panel reviewed electrocardiogram results to identify life-threatening manifestations of digoxin toxicity before and after DSAb treatment. Efficacy of treatment was assessed as rates of improvement in clinical parameters and cardiotoxic effects. Rates of adverse drug reactions were used to characterize safety. All data were analyzed with descriptive statistics.


RESULTS
Fourteen patients (mean [SD] age, 71.3 [10.4] years) were treated for chronic digoxin toxicity. At presentation, 12 patients had a heart rate of less than 45 beats per minute, 1 had third-degree heart block, and 1 had asystole. Mean serum digoxin level was 3.6 ng/mL. Eleven patients had abnormal renal function. After administration of DSAb, clinical parameters improved in all patients. Within 24 hours, cardiotoxicity resolved in 7 of 9 evaluable patients. Two adverse drug reactions possibly related to DigiFab occurred, both of which resolved with conventional measures. Two patients died from conditions unrelated to treatment.


CONCLUSIONS
The newer DSAb appears to be a safe and effective treatment for resolving digoxin toxicity in adults, as indicated by electrocardiogram and clinical assessments. Because patients with multiple comorbidities may be at greater risk for digoxin toxicity, they should be closely monitored during treatment with digoxin.
Rocky Vista University College of Osteopathic Medicine in Parker,Colorado, USA. tammi.schaeffer@rmpdc.org
Tammi H
TH
Schaeffer
Sara L
SL
Mlynarchek
Christopher F
CF
Stanford
João
J
Delgado
Christopher P
CP
Holstege
Dean
D
Olsen
Gregory M
GM
Bogdan
D000368:Aged; D000369:Aged, 80 and over; D000889:Anti-Arrhythmia Agents / Q000009:adverse effects* / Q000506:poisoning / Q000627:therapeutic use; D002316:Cardiotonic Agents / Q000009:adverse effects* / Q000506:poisoning / Q000627:therapeutic use; D054715:Cardiotoxins; D002908:Chronic Disease; D004077:Digoxin / Q000009:adverse effects* / Q000506:poisoning / Q000627:therapeutic use; D018450:Disease Progression; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007668:Kidney / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors
D000889:Anti-Arrhythmia Agents; D002316:Cardiotonic Agents; D054715:Cardiotoxins; D004077:Digoxin