Objective: As a highly protein-bound, time-dependent antibiotic, the duration for which the unbound concentration of ertapenem remains above the minimum inhibitory concentration (%T>MIC) is a critical pharmacokinetic/pharmacodynamic (PK/PD) parameter. In our clinical TDM practice, most enrolled patients were elderly (mean age 62± 21 years), with hypoalbuminemia present in 23/39 (59.0%), and the protein binding rate in these patients was significantly lower than literature-reported values. This study aimed to (1) establish a method for determining total and unbound ertapenem concentrations; (2) investigate factors influencing protein binding, focusing on hypoalbuminemia in the elderly; and (3) evaluate individualized dosing regimens for hypoalbuminemia elderly patients using a physiologically based pharmacokinetic (PBPK) model. Methods: Protein precipitation (for total concentration) and hollow-fiber centrifugal ultrafiltration (for unbound concentration) were used for sample pretreatment, followed by quantitative analysis using liquid chromatography–tandem mass spectrometry (LC-MS/MS). This method was applied to therapeutic drug monitoring (TDM) in clinical patients. A PBPK model was developed and validated using both our TDM data and published data to simulate dose–exposure relationships specifically in hypoalbuminemia elderly patients. Results: The developed method successfully quantified the total and unbound ertapenem concentrations. Clinical monitoring revealed that the protein binding rate in some patients was significantly lower than that reported in the literature. Correlation analysis indicated that albumin levels (p < 0.05) after outlier exclusion was the key factor influencing protein binding. The PBPK model demonstrated good agreement between the predicted and observed concentrations (AFE 0.78– 1.26). Simulations indicated that standard doses (1 g q24h) may lead to excessive unbound exposure in hypoalbuminemia elderly patients, while 0.5 g q12h improved target attainment and reduced peak concentrations. Conclusion: Albumin level plays a pivotal role in regulating ertapenem protein binding. Standard doses are unsuitable for hypoalbuminemia elderly patients, and TDM-guided dose adjustments are necessary. The PBPK model provides a valuable tool for individualized dosing in this specific population. Keywords: ertapenem, hollow fiber centrifugal ultrafiltration technology, therapeutic drug monitoring, PBPK model, hypoalbuminemia, elderly
Du et al. (Mon,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: