Abstract
The pharmacokinetics of Phenobarb and Phenytoin were evaluated in 14 neonatal patients. The average gestational age at birth was 32 (±5) weeks range, 26-41 weeks. The average post-conceptual age was 33 (±6) weeks, range 26-44. The average weight was 1.67 (±1.05) Kg, range 0.72-4.48. The patients were randomized as to which drug they would receive first. The drug was administered as a 20mg/Kg IV loading dose. If the first drug administered did not control the seizures, the second drug was given. Maintenance therapy was not begun, and serum levels were obtained at 2 hours, 12 hours, then every 12 hours after the dose until the phenytoin concentration was <10ug/ml and the phenobarbital concentration was <17ug/ml. At this point maintenance therapy was begun.
The average phenobarbital t½ was 173.0 (±169.3) hours, range 28.2-607.8. The volume of distribution for phenobarbital was 0.84(±0.26)1/Kg, range 0.24-1.20. The average phenytoin t½ = 100.1 (±112.1) hours, range 24.2-370.8. The volume of distribution for phenytoin was 1.58 (±0.54)1/Kg, range 1.03-3.24.
From this data, it would appear that a 25-30mg/Kg loading dose of either drug would produce serum levels in the middle to upper part of the therapeutic range. The calculated values are 30-36ug/ml for phenobarbital, and 16-19ug/ml for phenytoin.
Article PDF
Rights and permissions
About this article
Cite this article
Abroms, I., Bednarek, F., Hays, D. et al. 1230 The Pharmacokinetics of Phenobarb and Phenytoln in Neonates. Pediatr Res 15 (Suppl 4), 647 (1981). https://doi.org/10.1203/00006450-198104001-01256
Issue Date:
DOI: https://doi.org/10.1203/00006450-198104001-01256