Therapeutic drug monitoring
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Therapeutic drug monitoring (TDM) is increasingly used to optimize the dosing of beta-lactam antibiotics in critically ill patients. However, beta-lactams are inherently unstable and degrade over time. Hence, patient samples need to be appropriately handled and stored before analysis to generate valid results for TDM. The appropriate handling and storage conditions are not established, with few and conflicting studies on the stability of beta-lactam antibiotics in clinical samples. The aim of this study was to assess the preanalytical stability of piperacillin, tazobactam, meropenem, and ceftazidime in human plasma and whole blood using a liquid chromatography-tandem mass spectrometry method for simultaneous quantification. ⋯ Plasma samples for the TDM of piperacillin, tazobactam, meropenem, and ceftazidime should be processed within 6 hours if kept at room temperature and within 3 days if kept at 4°C. All long-term storage of samples should be at -80°C.