Digoxin Dosing for a 14-kg Child with Creatinine Clearance of 67 mL/min
For a 14-kg child with a creatinine clearance of 67 mL/min, the appropriate maintenance digoxin dose is 62.5 mcg (0.0625 mg) once daily, which represents a dose reduction from the standard pediatric dosing due to mild renal impairment. 1
Dosing Rationale
Standard Pediatric Dosing
- For children aged 2-5 years with normal renal function, the standard maintenance dose is 10-15 mcg/kg/day 1
- For a 14-kg child, this would typically be 140-210 mcg/day (approximately 7-10 mcg/kg/day when divided into once or twice daily dosing)
Renal Function Adjustment
The creatinine clearance of 67 mL/min indicates mild renal impairment requiring dose reduction 1:
- The FDA labeling provides a dosing table (Table 5) that correlates creatinine clearance with maintenance doses 1
- For a patient with CrCl of 60-70 mL/min and body weight in this range, the recommended dose falls in the 62.5-125 mcg range 1
- Given the child's weight of 14 kg and CrCl of 67 mL/min, 62.5 mcg once daily is the most appropriate starting dose 1
Critical Dosing Considerations
Digoxin clearance is primarily renal, and the maintenance dose formula accounts for this 1:
- Maintenance Dose = Peak Body Stores × % Daily Loss/100
- Where % Daily Loss = 14 + (CrCl/5) 1
- For CrCl 67: % Daily Loss = 14 + (67/5) = 27.4% daily
Target serum digoxin concentration should be 0.5-0.9 ng/mL for heart failure, as higher levels (>2 ng/mL) are associated with increased toxicity without additional therapeutic benefit in pediatric patients 2, 3
Monitoring Requirements
Essential monitoring parameters 1:
- Measure steady-state serum digoxin concentration after 7-11 days (approximately 5 half-lives)
- Monitor serum potassium and creatinine levels regularly, as hypokalemia increases digoxin toxicity risk 4
- Obtain baseline and periodic ECGs to assess for signs of toxicity 4
Common Pitfalls to Avoid
Do not use standard adult dosing formulas for children, as pediatric patients have:
- Larger volume of distribution relative to body weight 2
- Higher myocardial uptake of digoxin (higher myocardium/serum ratios) 2
- More rapid body clearance in infants and young children 5, 2
Avoid the misconception that children require higher serum levels - infants tolerate but do not require higher levels, and therapeutic effects occur at the same serum concentrations as adults (0.5-0.9 ng/mL) 2, 3
Adjust for concomitant medications: Spironolactone co-administration can affect digoxin clearance and may require dose adjustment 5
Dose Titration Strategy
- Start with 62.5 mcg once daily 1
- Check serum digoxin level after 7-11 days 1
- If level is <0.5 ng/mL and clinical response inadequate, may increase to 125 mcg once daily 1
- Doses may be increased every 2 weeks based on clinical response and serum levels 1
- Never exceed doses that produce serum levels >2 ng/mL, as this increases toxicity risk without additional benefit 2