Piperacillin Population Pharmacokinetics and Dosing Regimen Optimization in Critically Ill Children with Normal and Augmented Renal Clearance.

BACKGROUND: Critically ill children frequently display observed alterations of pharmacokinetic (PK) parameters, leading to a reduction in β-lactam concentrations. This study aimed to develop a PK population model for piperacillin in order to optimize individual dosing regimens.
METHODS: All children aged ≤ 18 years, weighing more than 2.5 kg, and receiving piperacillin infusions were included in this study. Piperacillin was quantified by high-performance liquid chromatography, and PK were described using the non-linear mixed-effect modeling software MONOLIX. Monte Carlo simulations were used to optimize dosing regimens in order to attain two PK targets: 50% fT>MIC and 100% fT>MIC.
RESULTS: We included 50 children with a median (range) postnatal age of 2.3 years (0.1-18), body weight (BW) of 11.9 kg (2.7-50), Pediatric Logistic Organ Dysfunction-2 (PELOD-2) severity score of 4 (0-16), and estimated glomerular filtration rate (eGFR) of 142 mL.min-1.1.73 m-2 (29-675). A one-compartment model with first-order elimination adequately described the data. Median (range) values for piperacillin clearance (CL) and volume of distribution were 3 L.h-1 (0.71-10) and 0.33 L.kg-1 (0.21-0.86), respectively. BW was integrated with the allometric relationship. eGFR and PELOD-2 severity score were the covariates explaining between-subject variability in CL and volume, respectively. According to the simulations, extended and continuous infusion provided the highest probability of reaching the target of 50% fT>MIC and 100% fT>MIC for normal and augmented renal clearance, respectively.
CONCLUSIONS: Unlike standard intermittent piperacillin dosing regimens, extended and continuous infusion allows the PK targets to be reached, for children with normal or augmented renal clearance. TRIAL REGISTRATION NUMBER: Registered at http://www.clinicaltrials.gov (NCT02539407).