Dosage programming of phenobarbital in neonatal seizures

Owing to the changes occurring in the organism as a result of biological maturation, disposition kinetics of phenobarbital in newborns is significantly different to that observed in the paediatric and adult populations. Moreover, the disposition parameters change constantly during the first days of life. The data on the serum levels of phenobarbital in 17 newborns were analysed to quantify the changes in the elimination half-life of phenobarbital during the first weeks of life. The half-life of the drug was estimated to be (mean +/- SD) 114.2 +/- 43.0 h, 73.19 +/- 24.17 h and 41.23 +/- 13.95 h in patients 1-10, 11-30 and 31-70 days old, respectively. According to these values and assuming phenobarbital serum levels of 20 mg/l to be safe and effective in neonatal seizures, the initial dosing recommended is 2.9, 4.8 and 6.0 mg/kg/day in newborns 1-10, 11-30 and 31-70 days old, respectively.