Pharmacokinetic study of valproic acid in a neonate.
Valproic acid was administered to a neonate (gestational age of 39 weeks) at 24 days post partum in an initial single dose of 7.5 mg/kg. Multiple serum samples were collected for 24 hours post dose. Valproic acid was continued and the study was repeated in the same child at 6 months of age at which time the dose had been increased to 13.5 mg/kg (27 mg/kg/day). Serum samples were collected for 12 hours post dose in this second study. A one-compartment model was assumed for calculation of the relevant pharmacokinetic parameters. The half-life (t 1/2) at 24 days of age was 17.2 hours, clearance (Cl) 0.18 ml/min/kg, and volume of distribution (Vd) 0.28 liter/kg. This t 1/2 was less than reported values in neonates younger than 10 days but longer than the average t 1/2 in adults. At 6 months of age, clearance had increased to 0.53 ml/min/kg, t 1/2 had decreased to 7.5 hours, while Vd was relatively unchanged (0.34 liter/kg). Factors possibly causing these changes include hepatic enzyme maturation and concomitant administration of anticonvulsant drugs.
D000367:Age Factors; D006801:Humans; D007231:Infant, Newborn; D007700:Kinetics; D008297:Male; D012640:Seizures / Q000188:drug therapy / Q000378:metabolism*; D013997:Time Factors; D014635:Valproic Acid / Q000378:metabolism* / Q000627:therapeutic use
D014635:Valproic Acid