What is the target serum digoxin (digitalis glycoside) level for atrial fibrillation?

Target Serum Digoxin Level for Atrial Fibrillation

The target serum digoxin level for atrial fibrillation should be 0.5-1.0 ng/mL, as higher levels have not shown superior outcomes and may be associated with increased risk. 1, 2

Dosing Recommendations

• Initial dosing:

  • Standard dose: 0.125-0.25 mg daily 2, 1
  • Lower dose (0.125 mg daily or every other day) should be used for:
    • Patients over 70 years old
    • Impaired renal function
    • Low lean body mass 2, 1
  • Loading doses are not necessary for chronic management 2

• Maintenance dosing:

  • Typical range: 0.125-0.375 mg daily 2
  • Higher doses (0.375-0.50 mg) are rarely needed or recommended 2

Monitoring Serum Levels

• Target range: 0.5-1.0 ng/mL 2, 1
• Check levels after 7-14 days of therapy (steady state)
• Levels above 1.0 ng/mL:
  • Do not provide additional clinical benefit 2, 1
  • May be associated with increased mortality risk 2
• Levels above 2.0 ng/mL are associated with toxicity 2, 1

Important Considerations

• Drug interactions that increase digoxin levels require dose reduction:

  • Amiodarone
  • Verapamil
  • Diltiazem
  • Quinidine
  • Clarithromycin/erythromycin
  • Itraconazole
  • Cyclosporine 2, 1

• Monitor for toxicity with:

  • Hypokalemia
  • Hypomagnesemia
  • Hypothyroidism
  • Hypercalcemia 2, 1

• Signs of toxicity:

  • Cardiac arrhythmias
  • Heart block
  • Bradycardia
  • Gastrointestinal symptoms (anorexia, nausea, vomiting)
  • Neurological complaints (visual disturbances, confusion) 2, 1

Role in AF Management

Digoxin is more effective for controlling resting heart rate than exercise heart rate in AF patients 2. For patients with AF and rapid ventricular response, high doses of digoxin (>0.25 mg daily) for rate control are not recommended 3. When additional rate control is needed, consider adding a beta-blocker or calcium channel blocker 2, 1.

The European Society of Cardiology (2016) notes that lower doses of digoxin (≤250 mg once daily), corresponding to serum levels of 0.5-0.9 ng/mL, may be associated with better prognosis 2.

Caution

While digoxin has traditionally been used for AF rate control, more recent guidelines suggest it should be considered as an adjunctive agent rather than first-line therapy unless heart failure is present 2, 1. Beta-blockers or calcium channel blockers are generally more effective for rate control, particularly during exercise 1.