Current knowledge has brought to light some of the pharmacokinetic cha
racteristics of phenobarbital during the neonatal period. We measured
plasma levels of fetal phenobarbital and its free fraction 24, 48, 72,
96 and 120 h after a single dose of the drug in 12 neonates with hype
rbilirubinemia. The pharmacokinetic characteristics of the samples, wh
ich were closer to normality than in mast of the reference models used
to date, e.g. anoxia and convulsions, are discussed in the light of e
arlier studies.