Simulation-Based Evaluation of PK/PD Indices for Meropenem Across Patient Groups and Experimental Designs
Anders N Kristoffersson1, Pascale David-Pierson2, Neil J Parrott2
1Department of Pharmaceutical Biosciences, Uppsala Universitet, Box 591, Uppsala, SE-751 24, Sweden. anders.kristoffersson@farmbio.uu.se.
Purpose:
Antibiotic dose predictions based on PK/PD indices rely on that the index type and magnitude is insensitive to the pharmacokinetics (PK), the dosing regimen, and bacterial susceptibility. In this work we perform simulations to challenge these assumptions for meropenem and Pseudomonas aeruginosa.
Methods:
A published murine dose fractionation study was replicated in silico. The sensitivity of the PK/PD index towards experimental design, drug susceptibility, uncertainty in MIC and different PK profiles was evaluated.
Results:
The previous murine study data were well replicated with fT > MIC selected as the best predictor. However, for increased dosing frequencies fAUC/MIC was found to be more predictive and the magnitude of the index was sensitive to drug susceptibility. With human PK fT > MIC and fAUC/MIC had similar predictive capacities with preference for fT > MIC when short t1/2 and fAUC/MIC when long t1/2.
Conclusions:
A longitudinal PKPD model based on in vitro data successfully predicted a previous in vivo study of meropenem. The type and magnitude of the PK/PD index were sensitive to the experimental design, the MIC and the PK. Therefore, it may be preferable to perform simulations for dose selection based on an integrated PK-PKPD model rather than using a fixed PK/PD index target.
Insights
Antibiotic dose predictions using PK/PD indices are sensitive to drug susceptibility and pharmacokinetics. Simulations suggest an integrated PK-PKPD model is preferable to fixed targets for meropenem dosing against Pseudomonas aeruginosa.
Area of Science:
- Pharmacology
- Microbiology
- Computational Biology
Background:
- Pharmacokinetic/pharmacodynamic (PK/PD) indices are crucial for predicting antibiotic efficacy.
- Current models often assume PK/PD index insensitivity to factors like bacterial susceptibility and pharmacokinetics (PK).
- Meropenem and Pseudomonas aeruginosa serve as a model system to challenge these assumptions.
Purpose of the Study:
- To evaluate the sensitivity of PK/PD indices to experimental design, bacterial susceptibility, and PK variability.
- To challenge the assumption that PK/PD index type and magnitude are independent of these factors.
- To compare the predictive performance of different PK/PD indices for meropenem.
Main Methods:
- In silico replication of a published murine dose fractionation study.
- Evaluation of PK/PD index sensitivity to variations in MIC, PK profiles, and experimental design.
- Utilizing a longitudinal PK/PD model based on in vitro data.
Main Results:
- The time above the minimum inhibitory concentration (fT>MIC) best predicted outcomes in the murine model.
- Predictive capacity shifted to the area under the concentration-time curve divided by MIC (AUC/MIC) with increased dosing frequency.
- Both indices' magnitudes were sensitive to bacterial susceptibility, and human PK data showed similar predictive capacities for fT>MIC and AUC/MIC.
Conclusions:
- A PK/PD model successfully predicted in vivo meropenem study outcomes.
- PK/PD index type and magnitude are sensitive to experimental design, MIC, and PK.
- Integrated PK-PKPD modeling is recommended over fixed PK/PD targets for optimizing antibiotic dosing.
More Related Videos
Related Concept Videos
Pharmacodynamic Models: Overview
Analysis of Population Pharmacokinetic Data
Impact of Pharmacokinetic–Pharmacodynamic Models: Regulatory Decisions
Dosage Regimens: Partial Pharmacokinetic Parameters
Pharmacokinetic–Pharmacodynamic Relationship: Problems
Bioequivalence Experimental Study Designs: Repeated Measures, Cross-Over, Carry-Over, and Latin Square Designs


