Digoxin Toxicity

Question 1

How does digoxin toxicity occur?

Answer 1

• Digoxin has a narrow therapeutic index and serum levels should be followed closely, particularly in patients with unstable renal function.
• Clinical benefits may not be related to serum levels. Although serum digoxin levels of 0.8 – 2.0 ng/mL are considered therapeutic, toxicity can also occur in this range. Drug interactions with digoxin are common and may lead to toxicity (erythromycin, tetracycline, quinidine, verapamil, flecainide and amiodarone).

Question 2

What are the subjective findings associated with digoxin toxicity?

Answer 2

Subjective: N/V/D, blurred vision, green halos, anorexia, abdominal pain, fatigue, dizziness, confusion, HA, occasional hallucinations

Question 3

What lab/diagnostic tests are associated with digoxin toxicity?

Answer 3

• EKG: SV tachy dysrhythmias, SV brady dysrhythmias, atrial tachy dysrhythmias, VT
• Hypotension
• Where hyperkalemia may be seen in patients with acute overdose the electrolyte abnormalities of hypokalemia can also occur and can exacerbate toxicity
• Digoxin level > 2.4 ng/ml.

Question 4

How do you manage patients with digoxin toxicity?

Answer 4

1. Continuous EKG monitoring, dysrhythmias may need lidocaine
2. Monitor and correct serum potassium levels but maintain them in a high normal range
3. Activated charcoal 1 gm/kg PO/NG
4. Digoxin immune Fab (DigiFab)
   * Dose is based for the following events: acute toxicity of known amount OR acute toxicity of unknown amounts OR chronic toxicity

Digoxin levels administered during DigiFab treatment do not correlate with clinical toxicity since lab assays do not distinguish between Fab-bound and unbound digoxin. The levels may show a 10-20 fold increase. Patient’s clinical response using other parameters are a better indication of response to therapy