The influence of asphyxia on phenobarbital dosing requirements in neonates.

phenobarbital dosing requirements and plasma clearance were examined for asphyxiated and nonasphyxiated neonates. The gestational age, postnatal age, duration of phenobarbital therapy and plasma phenobarbital concentrations were similar for the two groups. The plasma phenobarbital clearance was 4.1 +/- 1.0 (SD) and 8.7 +/- 3.9 (SD) ml/kg/h for asphyxiated and nonasphyxiated neonates, respectively. Asphyxiated neonates only require about half the maintenance dose of nonasphyxiated neonates to achieve similar plasma concentrations.