Acetaminophen elimination kinetics in neonates, children, and adults

Clin Pharmacol Ther. 1976 Mar;19(3):284-94. doi: 10.1002/cpt1976193284.


The elimination of acetaminophen (APAP) following an oral dose of 10 mg/kg in newborn infants, children, and adults was compared. Urinary excretion of unchanged APAP, APAP-sulfate, and APAP-glucuronide was complete within 30 hr at all ages. Higher percentages of the dose were excreted in the urine as APAP-sulfate in neonates (0-2 days old) and children (3-9 yr old) than in 12-yr old children and adults. A pharmacokinetic analysis indicated that the higher rate of APAP-sulfate formation in younger age groups apparently compensated for a deficiency in glucuronide formation. No dramatic age-related differences in the overall elimination rate constant for APAP were observed despite the quantitative changes in the metabolic pathways during early childhood.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetaminophen / metabolism*
  • Acetaminophen / urine
  • Adult
  • Age Factors
  • Child
  • Child, Preschool
  • Female
  • Glucuronates / urine
  • Half-Life
  • Humans
  • Infant
  • Infant, Newborn*
  • Kinetics
  • Male
  • Models, Biological
  • Sulfates / urine


  • Glucuronates
  • Sulfates
  • Acetaminophen