Pharmacokinetics of esmolol in children

The pharmacokinetics and concentration-response relationships of intravenous esmolol were investigated in 20 children undergoing indicated cardiac electrophysiologic testing. A loading dose of 600 micrograms/kg was infused for 2 minutes. An infusion of esmolol was initiated and dosage was titrated until beta-blockade occurred. Serial esmolol blood samples were obtained for pharmacokinetic analysis. Non-compartmental pharmacokinetic analysis of the data revealed the following parameter estimates (mean +/- SD): volume of distribution at steady state, 2.0 +/- 1.4 L/kg; total body clearance, 321.2 +/- 238.8 ml/kg/min; and terminal elimination half-life, 4.5 +/- 2.1 minutes. There was a significant correlation between mean esmolol concentrations and mean percentage of reductions of mean arterial pressures and heart rates at each sample time (p less than 0.001). The doses of esmolol required for beta-blockade (mean +/- SD, 535 +/- 180 micrograms/kg/min) in children were considerably higher than those typically used in adults. Esmolol should prove useful in children in the acute management of cardiac arrhythmias and hypertension.