Pharmacokinetics of Single Dose Intravenous Paracetamol in Children

Abstract

A new intravenous formulation containing paracetamol is now available and widely used in children, but with limited paediatric pharmacokinetic data. This study was aimed at determining the effects of age on the pharmacokinetics (PK) of this formulation of paracetamol in children. Blood samples were obtained from 24 children at 0, 15, 30 minutes, then 1, 2, 4, 6 and 8 hours after the administration of 15 mg kg -1 of IV paracetamol. Paracetamol was quantified using an HPLC-UV method, with lower limit quantification of 2200 pg and an intra-assay coefficient of variation of 3%. In the paediatric age groups 2-5 years, 6 -10 years and 11-14 years, total clearance (CLt) in kg l -1 h -1 , was 0.41(0.20-0.57), 0.31(0.14-1.10) and 0.37(0.09-0.55) respectively; volume of distribution (Vd) in litres was 0.90(0.7-1.1), 0.95(0.7-1.6) and 0.90(0.4 -1.3) respectively; and elimination half-lives (t1/2) in hours was 1.7(1.1-2.6), 2.2(0.6-3.5) and 1.6(1.1-4.7), respectively. The PK parameters (CLt, Vd and t1/2) obtained did not differ significantly among the paediatric age groups (the p-value in all cases was greater than 0.05). In children 2-14 years, there were no significant relationships between the PK parameters and age, weight, height, body weight or body surface area.