Pharmacokinetics of digoxin in children with congestive heart failure aggravated by other diseases

To determine individual digoxin level variations and the effect of some common diseases those aggravate congestive heart failure (CHF) on digoxin pharmacokinetics in children.

Digoxin pharmacokinetics was evaluated in 11 children with CHF and an additional disease, such as rheumatic fever, anemia or infections. Digoxin plasma levels were monitored in patients on multiple-dose regime. Setting. Third level pediatric hospital.

Pharmacokinetic parameters showed extensive variation; median values were: elimination half-life 42.0 hrs (8.3-77.0), volume of distribution 1.01 L/kg (0.654-6.25), and clearance 15.0 mL/kg/h (6.0-331.8), which differed from results in patients with only CHF, reported previously. Dosage schemes in use at the Cardiology Service produced the following results: 40.5% of patients reached therapeutic levels, 10.8% toxic levels and 48.6% subtherapeutic levels.

The range of dosage required in order to adjust individual treatments was very wide, leading us to the conclusion that therapeutic schemes for this population should be individualized based on their pharmacokinetic parameters, and therapeutic monitoring of drugs should be performed.