Digoxin pharmacokinetics and dosage requirements in pediatric patients.

The pharmacokinetic properties and dosage guidelines for digoxin in pediatric patients with congestive heart failure are reviewed. Interindividual variability in the pharmacokinetics of digoxin in pediatric patients has been reported. The bioavailability of digoxin elixir in newborns and infants is similar to adults; however, the apparent volume of distribution has been reported to be greater in infants than in adults. The total body clearance of digoxin is lowest in premature and full-term neonates and highest in infants aged one month to one year. The elimination half-life of digoxin has been reported to vary significantly among the different age groups of pediatric patients. The usefulness of monitoring digoxin serum concentrations in pediatric patients remains a controversial issue. Serum samples should be drawn under steady-state conditions to evaluate predicted daily maintenance doses. Although infants have been reported to be more tolerant than adults to elevated serum digoxin concentrations, infants experience a higher rate of digoxin toxicity than previously realized. Recent studies have shown appropriate therapeutic response in neonates and infants when low dosages of digoxin are administered. Low digoxin dosage regimens should be used initially for infants with congestive heart failure. If the clinical response is unsatisfactory or if toxicity is suspected, steady-state serum concentrations should be determined and the dosage adjusted.