Intravenous Digoxin Dosing Regimen for Atrial Fibrillation with Dacar Response in Acute Decompensated Heart Failure
For acute decompensated heart failure with atrial fibrillation requiring a Dacar response, the recommended intravenous digoxin loading dose is 8-12 mcg/kg, with half the total dose administered initially, followed by one-quarter of the loading dose every 6-8 hours twice, targeting a serum concentration of 0.6-1.2 ng/mL. 1
Initial Loading Dose Strategy
The FDA-approved loading dose regimen for intravenous digoxin in adults with atrial fibrillation is:
- Total IV loading dose: 8-12 mcg/kg 1
- Administration schedule:
- Give half the total loading dose initially
- Then give ¼ of the loading dose every 6-8 hours twice 1
For example, in a 70 kg patient:
- Total loading dose: 560-840 mcg
- Initial dose: 280-420 mcg
- Followed by two doses of 140-210 mcg each at 6-8 hour intervals
Important Administration Considerations
- Administer the dose over at least 5 minutes to prevent systemic and coronary vasoconstriction 1
- Avoid bolus administration due to risk of cardiovascular adverse effects 1
- Digoxin can be administered undiluted or diluted with a 4-fold or greater volume of sterile water, normal saline, or 5% dextrose 1
- Monitor ECG and vital signs during administration
Maintenance Dosing
After loading, the maintenance dose should be determined based on:
- Lean body weight
- Renal function
- Age
- Concomitant medications
For adults with normal renal function, the recommended intravenous maintenance dose is 2.4-3.6 mcg/kg/day given once daily 1.
Monitoring Parameters
- Target serum concentration: 0.6-1.2 ng/mL 2
- Serum levels >2 ng/mL are associated with toxicity 1
- Check serum digoxin levels early during therapy, especially in patients with renal impairment 2
- Obtain levels at least 6 hours after the last dose or just before the next scheduled dose 1
- Monitor serum electrolytes (especially potassium, calcium, and magnesium) and renal function regularly 2
Special Considerations and Cautions
Risk Factors for Toxicity
- Advanced age
- Renal impairment
- Low lean body mass
- Electrolyte abnormalities (hypokalemia, hypercalcemia, hypomagnesemia)
- Drug interactions (amiodarone, verapamil, diltiazem, certain antibiotics, quinidine) 2, 1
Contraindications
- Ventricular fibrillation
- Second or third-degree heart block without a pacemaker
- Pre-excitation syndromes (Wolff-Parkinson-White)
- Previous digoxin intolerance 2, 1
Signs of Toxicity
- Cardiac arrhythmias (sinoatrial and AV block, atrial and ventricular arrhythmias)
- Gastrointestinal symptoms (anorexia, nausea, vomiting)
- Neurological symptoms (confusion, visual disturbances) 2, 1
Long-term Management Considerations
For long-term management after stabilization:
- Consider switching to oral digoxin with appropriate dose adjustment (IV digoxin has 100% bioavailability vs. 60-80% for oral tablets) 1
- In the long term, a beta-blocker, either alone or in combination with digoxin, is the preferred treatment for rate control in patients with atrial fibrillation and heart failure with reduced ejection fraction 2
- For patients with severe heart failure symptoms, digoxin may be used in combination with beta-blockers for rate control 2
Remember that while digoxin is useful for initial control of ventricular rate in patients with rapid atrial fibrillation and may be considered in decompensated heart failure patients prior to initiation of a beta-blocker, it does not improve mortality in heart failure patients 2, 3.