Massive digitoxin intoxication treated with digoxin-specific antibodies in a child

Area of Science:

• Cardiology
• Toxicology
• Pharmacology

Background:

• Digitalis glycosides, digitoxin and digoxin, are commonly prescribed for heart conditions.
• Digitoxin has a narrower therapeutic index and longer half-life than digoxin, increasing toxicity risk.
• Massive digitoxin intoxication can lead to severe cardiac arrhythmias and is life-threatening.

Observation:

• A 20-month-old girl presented with severe digitoxin intoxication (serum level 629 ng/ml).
• Clinical signs included somnolence, bradycardia, and first-degree atrioventricular block.
• Treatment involved fractional administration of digoxin-specific antibody fragments (Fab).

Findings:

• Rapid improvement in clinical signs of digitalis toxicity was observed during Fab therapy.
• Free serum digitoxin levels became undetectable after 6 vials (480 mg) of Fab.
• Measurable free serum digitoxin reappeared on days 6 and 7, indicating a potential rebound effect.

Implications:

• Digoxin-specific Fab fragments are effective in managing massive digitoxin intoxication, even with lower binding affinity.
• The potential for a delayed rebound phenomenon necessitates careful patient monitoring for several days after Fab administration.
• This case highlights the utility of antibody fragment therapy in severe cardiac glycoside poisoning.