What is the recommended dose of digoxin (digitalis glycoside) for controlling heart rate in atrial fibrillation?

Digoxin Dosing for Heart Rate Control in Atrial Fibrillation

For heart rate control in atrial fibrillation, the recommended digoxin dose is 0.25 mg PO every 2 hours up to 1.5 mg total for loading, followed by a maintenance dose of 0.125-0.375 mg daily, with adjustments based on renal function, age, and body weight. 1

Initial Dosing Strategy

Loading Dose (for rapid rate control)

• Intravenous: 0.25 mg IV every 2 hours, up to a total loading dose of 1.5 mg 1
• Oral: 0.25 mg PO every 2 hours, up to a total loading dose of 1.5 mg 1
• Onset of action: Approximately 2 hours 1

Maintenance Dose

• Standard range: 0.125-0.375 mg daily 1, 2
• Typical starting dose: 0.125-0.25 mg daily 2, 3

Dose Adjustments

Patient Factors Requiring Lower Doses (0.125 mg daily or less)

• Age >70 years 2
• Impaired renal function 2, 3
• Low lean body weight 2, 3

Renal Function Adjustments

Renal Function	eGFR	Recommended Dose
Normal	>60 mL/min	0.25 mg daily
Mild impairment	45-59 mL/min	0.125 mg daily
Moderate impairment	30-44 mL/min	0.125 mg daily or every other day
Severe impairment	<30 mL/min	0.0625-0.125 mg every other day

Monitoring and Target Levels

Target Heart Rate

• Resting heart rate: 60-80 bpm 1
• Exercise heart rate: 90-115 bpm 1

Therapeutic Serum Levels

• Target serum concentration: 0.5-0.9 ng/mL 2
• Check levels 5-7 days after initiation 2
• Toxicity risk increases with levels >2 ng/mL 4

Important Considerations

Efficacy Limitations

• Digoxin alone is often insufficient for rate control during exercise 5
• Consider combination therapy with beta-blockers or non-dihydropyridine calcium channel blockers for better rate control 1, 6

Contraindications

• Wolff-Parkinson-White syndrome with pre-excited AF (Class III: Harm) 1
• Significant AV block without pacemaker 2
• Sinus node dysfunction without pacemaker 2

Drug Interactions

• Amiodarone, verapamil, quinidine, and other medications can increase digoxin levels 2
• Reduce digoxin dose by 30-50% when these medications are initiated 2

Monitoring for Toxicity

• Signs of toxicity: confusion, nausea, anorexia, visual disturbances, cardiac arrhythmias 2
• Monitor serum potassium and magnesium levels (hypokalemia and hypomagnesemia increase toxicity risk) 2

Clinical Recommendations

1. In patients with AF and heart failure with reduced ejection fraction (HFrEF), digoxin is effective for controlling resting heart rate (Class I recommendation) 1

2. For patients with AF and normal heart function, beta-blockers or calcium channel blockers are preferred first-line agents, with digoxin as an adjunct 1

3. Combination therapy with digoxin plus a beta-blocker (or non-dihydropyridine calcium channel antagonist in patients with preserved ejection fraction) is reasonable to control both resting and exercise heart rate (Class IIa recommendation) 1

4. Higher doses of digoxin (>0.25 mg daily) for rate control in AF are not recommended 4

5. For acute rate control in critically ill patients, a median total loading dose of 750 mcg (approximately 11 mcg/kg) distributed over six-hour intervals may be considered 7

Remember that digoxin has a narrow therapeutic window, and careful dosing and monitoring are essential to maximize benefits while minimizing toxicity risks.