Digoxin Dosing in Pediatric Patients with Congestive Heart Failure
For pediatric patients with heart failure, digoxin maintenance dosing should be 10-15 mcg/kg/day for children aged 2-5 years, 7-10 mcg/kg/day for ages 5-10 years, and 3-5 mcg/kg/day for children over 10 years, with doses divided twice daily for children under 10 years of age. 1
Age-Specific Maintenance Dosing
The FDA-approved dosing schedule provides clear age-based guidelines for pediatric patients with normal renal function 1:
- Ages 2-5 years: 10-15 mcg/kg/day divided into twice-daily doses 1
- Ages 5-10 years: 7-10 mcg/kg/day divided into twice-daily doses 1
- Children over 10 years: 3-5 mcg/kg/day, typically given once daily (adult dosing proportional to body weight) 1
Divided daily dosing is recommended for infants and young children under age 10, while children over 10 years require adult dosages in proportion to their body weight. 1
Critical Considerations for Neonates and Infants
In the newborn period, renal clearance of digoxin is diminished and suitable dosage adjustments must be observed, especially in premature infants. 1 Neonates and young infants (under 4 months) achieve significantly higher serum digoxin levels than older patients on comparable weight-based dosing, with mean levels of 2.2-2.6 ng/mL compared to 1.0-1.4 ng/mL in older children 2.
Despite historical beliefs that infants require higher doses, recent evidence demonstrates that low digoxin dosage regimens should be used initially for infants with congestive heart failure, as appropriate therapeutic response occurs with lower doses. 3 The total body clearance of digoxin is lowest in premature and full-term neonates and highest in infants aged one month to one year 3.
Therapeutic Monitoring in Pediatric Patients
Target serum digoxin concentrations in pediatric patients should be 1.1-1.7 ng/mL, as higher levels (>2 ng/mL) are not associated with greater inotropic effects but are associated with increased frequency of toxic effects. 4 Some researchers suggest that infants and young children tolerate slightly higher serum concentrations than adults, but this tolerance does not indicate a therapeutic need for higher levels 1.
Serum samples should be drawn under steady-state conditions to evaluate predicted daily maintenance doses, and if clinical response is unsatisfactory or toxicity is suspected, steady-state serum concentrations should be determined and dosage adjusted. 3
Renal Impairment Adjustments
In children with renal disease, digoxin must be carefully titrated based upon clinical response, as standard dosing guidelines assume normal renal function. 1 The pharmacokinetic variability in pediatric patients necessitates individualized dosing adjustments when renal function is compromised 3.
Loading Doses
Loading doses are generally not necessary for chronic heart failure management in pediatric patients. 5 When loading is required for acute rate control in atrial fibrillation, peak digoxin body stores larger than 8-12 mcg/kg may be used, but this exceeds typical heart failure dosing 1.
Common Pitfalls and Safety Considerations
Infants experience a higher rate of digoxin toxicity than previously realized, particularly when receiving concomitant diuretic therapy. 3, 4 The apparent volume of distribution is greater in infants than adults, and elimination half-life varies significantly among different pediatric age groups 3.
Not all infants with congestive heart failure benefit from digoxin therapy—in one study, only 6 of 21 infants showed an inotropic response by echocardiography, though 12 had clinical benefit. 6 This highlights that clinical improvement may occur without measurable inotropic response 6.
Digoxin toxicity in pediatric patients is commonly associated with serum levels >2 ng/mL but may occur at lower levels with hypokalemia, hypomagnesemia, or hypothyroidism. 5 Concomitant medications such as quinidine, verapamil, spironolactone, flecainide, and amiodarone can increase serum digoxin levels and toxicity risk 5.
Formulation Considerations
When changing between digoxin formulations, bioavailability differences must be considered: 100 mcg and 200 mcg of Digoxin Solution in Capsules are approximately equivalent to 125 mcg and 250 mcg doses of Digoxin Tablets and Elixir Pediatric, respectively. 1