In order to characterize the variation in pharmacokinetics of paracetamol across the human age span, we performed a population pharmacokinetic analysis from preterm neonates to adults with specific focus on clearance. Concentration-time data obtained in 220 neonates (post-natal age 1-76 days, gestational age 27-42 weeks), infants (0.11-1.33 yrs), children (2-7 yrs) and adults (19-34 yrs) were analyzed using NONMEM 7.2. In the covariate analysis, linear functions, power functions, and a power function with a bodyweight-dependent exponent were tested. Between preterm neonates and adults, linear bodyweight functions were identified for Q2, Q3, V1, V2, and V3, while for CL a power function with a bodyweight-dependent exponent k was identified (CLi=CLp×(BW/70)k). The exponent k was found to decrease in a sigmoidal manner with bodyweight from 1.2 to 0.75, with half the decrease in exponent reached at 12.2kg. No other covariates such as age were identified. A pharmacokinetic model for paracetamol characterizing changes in pharmacokinetic parameters across the pediatric age-range was developed. Clearance was found to change in a nonlinear manner with bodyweight. Based on the final model, dosing guidelines are proposed from preterm neonates to adolescents resulting in similar exposure across all age ranges.

allometry, clearance, paracetamol, pediatric, pharmacokinetics,
Journal of Clinical Pharmacology
Department of Pediatric Surgery

Wang, C, Allegaert, K.M, Tibboel, D, Danhof, M, van der Marel, C.D, Mathot, R.A, & Knibbe, C.A.J. (2014). Population pharmacokinetics of paracetamol across the human age-range from (pre)term neonates, infants, children to adults. Journal of Clinical Pharmacology, 54(6), 619–629. doi:10.1002/jcph.259