Pharmacokinetics of meropenem in critically ill patients in Saudi Arabia

Evaluation of pharmacokinetic pharmacodynamic target attainment of meropenem in pediatric patients

BACKGROUND

Meropenem is a widely used carbapenem for treating severe pediatric infections. However, few studies have assessed its pharmacokinetics/pharmacodynamics (PK/PD) in pediatric patients. This study aimed to evaluate the proportion of Saudi pediatric patients achieving the PK/PD target of meropenem.

METHODS

A prospective observational study was conducted at King Saud University Medical City from July to September 2022. Pediatric patients receiving meropenem for suspected or proven infections were included in the study. The primary outcome was the percentage of patients achieving the recommended PK/PD target for critically ill or non-critically ill pediatric patients.

RESULTS

The study included 30 patients (nine neonates and 21 older pediatric patients). All neonates were critically ill. Among them, 55 % achieved the PK/PD target of 100 % free time above the MIC. In older ICU pediatric patients, only 11 % attained this target, whereas 58 % of older pediatrics in the general wards achieved the PK/PD target of 50 % free time above the MIC. Augmented renal clearance (ARC) was identified in 57 % of our pediatric patient population, none of whom achieved the recommended PK/PD targets. The median trough concentrations in patients with and without ARC were 0.75 and 1.3 μg/mL, respectively (P < 0.05).

CONCLUSIONS

The majority of patients in our cohort did not achieve the PK/PD target for meropenem. ARC emerged as a major risk factor for target attainment failure in both critically ill and non-critically ill pediatric patients.

Meropenem Model-Informed Precision Dosing in the Treatment of Critically Ill Patients: Can We Use It?

The number of pharmacokinetic (PK) models of meropenem is increasing. However, the daily role of these PK models in the clinic remains unclear, especially for critically ill patients. Therefore, we evaluated the published meropenem models on real-world ICU data to assess their suitability for use in clinical practice. All models were built in NONMEM and evaluated using prediction and simulation-based diagnostics for the ability to predict the subsequent meropenem concentrations without plasma concentrations (a priori), and with plasma concentrations (a posteriori), for use in therapeutic drug monitoring (TDM). Eighteen PopPK models were included for evaluation. The a priori fit of the models, without the use of plasma concentrations, was poor, with a prediction error (PE)% of the interquartile range (IQR) exceeding the ±30% threshold. The fit improved when one to three concentrations were used to improve model predictions for TDM purposes. Two models were in the acceptable range with an IQR PE% within ±30%, when two or three concentrations were used. The role of PK models to determine the starting dose of meropenem in this population seems limited. However, certain models might be suitable for TDM-based dose adjustment using two to three plasma concentrations.

Improving the efficacy for meropenem therapy requires a high probability of target attainment in critically ill infants and children

Probability of target attainment is the key factor influencing the outcome of meropenem therapy. The objective of the present study was to evaluate the relationship between the time in which the plasma free concentration of meropenem exceeds the minimum inhibitory concentration of pathogens (fT_>MIC) during therapy and the clinical outcome of treatment to optimize meropenem therapy. Critically ill children with infections who had received intravenous meropenem monotherapy were included. The relationship between fT_>MIC of meropenem and effectiveness and safety were explored. Data from 53 children (mean age ± standard deviation, 26 months ± 38) were available for final analysis. Children with fT_>MIC ≥ 5.6 h (n = 14) had a more significant improvement in antibacterial efficacy in terms of decrease in fever (p = 0.02), white blood cell count (p = 0.014), and C-reactive protein (p = 0.02) compared with children with fT_>MIC < 5.6 h (n = 39) after meropenem therapy completed. No drug-related adverse events were shown to have a causal association with meropenem therapy. Our study shows the clinical benefits of sufficient target attainment of meropenem therapy. Meeting a suitable pharmacodynamic target attainment of meropenem is required to ensure better antibacterial efficacy in critically ill infants and children.

Clinical Trial Registration:clinicaltrials.gov, Identifier NCT03643497.