Simple and accurate quantitative analysis of cefiderocol and ceftobiprole in human plasma using liquid chromatography-isotope dilution tandem mass spectrometry: interest for their therapeutic drug monitoring and pharmacokinetic studies

This study aimed to develop and validate a rapid, selective, and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous quantification of cefiderocol and ceftobiprole in human plasma. The primary objective was to facilitate therapeutic drug monitoring (TDM) and support pharmacokinetic (PK) and pharmacodynamic (PD) studies, particularly in critically ill patients where drug concentration variability can significantly impact efficacy and toxicity. The methodology involved a straightforward single-step protein precipitation for sample preparation, followed by chromatographic separation on a Waters Acquity UPLC BEH C18 column using a linear gradient elution. Detection was performed with a Shimadzu MS 8060 triple quadrupole tandem mass spectrometer in positive ionization mode. The developed method demonstrated excellent analytical performance, meeting all bioanalytical validation criteria for specificity, sensitivity, linearity, precision, accuracy, matrix effect, extraction recovery, limit of quantification, dilution integrity, and analyte stability. The calibration curves exhibited linearity over a wide range (1-200 mg/L for cefiderocol and 0.5-100 mg/L for ceftobiprole) with high regression coefficients. The total analysis time per run was efficiently reduced to 5 minutes. This validated method was successfully applied to measure plasma concentrations of both antibiotics in critically ill patients, proving its utility for routine TDM and optimizing antibiotic therapy in complex clinical settings.

This study aimed to develop and validate a rapid, selective, and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous quantification of cefiderocol and ceftobiprole in human plasma. The primary objective was to facilitate therapeutic drug monitoring (TDM) and support pharmacokinetic (PK) and pharmacodynamic (PD) studies, particularly in critically ill patients where drug concentration variability can significantly impact efficacy and toxicity. The methodology involved a straightforward single-step protein precipitation for sample preparation, followed by chromatographic separation on a Waters Acquity UPLC BEH C18 column using a linear gradient elution. Detection was performed with a Shimadzu MS 8060 triple quadrupole tandem mass spectrometer in positive ionization mode. The developed method demonstrated excellent analytical performance, meeting all bioanalytical validation criteria for specificity, sensitivity, linearity, precision, accuracy, matrix effect, extraction recovery, limit of quantification, dilution integrity, and analyte stability. The calibration curves exhibited linearity over a wide range (1-200 mg/L for cefiderocol and 0.5-100 mg/L for ceftobiprole) with high regression coefficients. The total analysis time per run was efficiently reduced to 5 minutes. This validated method was successfully applied to measure plasma concentrations of both antibiotics in critically ill patients, proving its utility for routine TDM and optimizing antibiotic therapy in complex clinical settings. Research Background and Significance The emergence of multidrug-resistant bacteria has intensified the clinical demand for novel antibiotics such as cefiderocol and ceftobiprole, both advanced cephalosporins with potent