What is Digoxin used for?

Uses of Digoxin in Clinical Practice

Digoxin is primarily used for heart failure with reduced ejection fraction and atrial fibrillation rate control, but should be considered as an adjunctive therapy rather than first-line treatment due to its narrow therapeutic window and potential toxicity. 1, 2

Primary Indications

1. Heart Failure with Reduced Ejection Fraction

• Used in patients with symptomatic heart failure (NYHA class II-IV) with reduced ejection fraction (<40%)
• Benefits include:
  • Improved symptoms and quality of life
  • Enhanced exercise tolerance
  • Reduced hospitalization for worsening heart failure
  • No effect on overall mortality 1
• Patient selection criteria:
  • Should be considered after or in addition to first-line therapies (diuretics, ACE inhibitors/ARBs, beta-blockers)
  • Most appropriate for patients with persistent symptoms despite optimal therapy with neurohormonal antagonists 1

2. Atrial Fibrillation Rate Control

• Used for ventricular rate control in patients with chronic atrial fibrillation
• More effective when combined with beta-blockers, particularly for rate control during exercise
• Should be considered as an adjunctive agent rather than monotherapy for rate control 1

Dosing Considerations

• Standard dosing: 0.125-0.25 mg daily
• Lower doses (0.125 mg daily or every other day) recommended for:
  • Elderly patients (>70 years)
  • Patients with impaired renal function
  • Patients with low lean body mass 1
• Loading doses are not necessary for chronic heart failure management
• Target serum concentration: 0.5-1.0 ng/mL 1
• Higher serum concentrations (≥1.2 ng/mL) associated with increased mortality risk 3

Contraindications and Precautions

• Absolute contraindications:

  • Significant sinus or atrioventricular block without a permanent pacemaker
  • Pre-excitation syndromes
  • Previous digoxin intolerance 1, 2

• Use with caution in:

  • Hyperthyroidism (increased sensitivity to digoxin)
  • Hypercalcemia (predisposes to digoxin toxicity)
  • Patients taking medications that affect digoxin levels (amiodarone, verapamil, quinidine) 4, 2
  • Elderly patients and those with renal impairment 2

Monitoring and Toxicity Prevention

• Monitor serum electrolytes (especially potassium, magnesium, and calcium)
• Hypokalemia and hypomagnesemia increase risk of digoxin toxicity
• Signs of toxicity include:
  • Cardiac arrhythmias (most common in children)
  • Gastrointestinal symptoms (anorexia, nausea, vomiting)
  • Visual disturbances (blurred or yellow vision)
  • Neurological symptoms (confusion, weakness, dizziness) 2

Important Clinical Considerations

• Not indicated for acute heart failure exacerbations or stabilization
• In atrial fibrillation, beta-blockers are generally preferred for rate control, with digoxin as an adjunctive agent
• Recent evidence suggests increased mortality risk in patients with atrial fibrillation without heart failure 5
• The risk of death appears to be independently related to serum digoxin concentration, with higher risk at concentrations ≥1.2 ng/mL 3

Despite newer medications for heart failure management, digoxin remains a useful adjunctive therapy when used appropriately and with careful monitoring of serum levels and electrolytes to prevent toxicity.