Phenobarbitone dosage in neonatal convulsions.

In order to find the optimal dosage schedule of phenobarbitone for neonatal convulsions, four groups of patients were studied. Twelve infants (group 1) received a mean phenobarbitone dose of 9.5 mg/kg a day given intramuscularly for 3 days followed by 5.8 mg/kg a day given intramuscularly and then orally. Six infants (group 2) received a mean intravenous loading dose of 9.5 mg/kg followed by 6.8 mg/kg a day given intramuscularly or orally. Nine infants (group 3) received a mean loading dose of 14.9 mg/kg intravenously followed by a maintenance dose of 5.9 mg/kg a day. Thirteen patients (group 4) received a mean intramuscular loading dose of 15.2 mg/kg followed by 5.9 mg/kg a day. Blood samples were taken regularly and phenobarbitone levels were determined by gas liquid chromatography. A mean intravenous or intramuscular loading dose of 15 mg/kg of phenobarbitone safely achieved therapeutic levels within 2 hours of injection and high therapeutic levels were maintained with a dose of 6 mg/kg a day.