UPLC–MS/MS method for therapeutic drug monitoring of 10 antibiotics used in intensive care units

A large variation in the levels of different ß‐lactams and other antibiotics used in critically ill patients has been documented. The aim of this study is to establish and validate a fast, ultra‐performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method for the simultaneous analysis of ten antibiotics (Meropenem, Cefepime, Ceftazidime, Piperacillin, Benzylpenicillin, Ampicillin, Flucloxacillin, Linezolid, and Sulfamethoxazole/Trimethoprim) in human plasma according to European Medicines Agency (EMA) guidelines. Protein precipitation with ice‐cold methanol containing 9 isotopically labeled internal standards was used for sample clean up. Antibiotics were detected, following a 4‐minute gradient separation, in multiple reactions monitoring (MRM) using API 4000 instrument equipped with electrospray source operating in positive ion mode. The lower limit of quantification was 0.1 mg/L for Meropenem, Ceftazidime, Piperacillin, Ampicillin, Flucloxacillin, and Sulfamethoxazole; 0.05 mg/L for Cefepime, Benzylpenicillin, and Trimethoprim; and 0.02 mg/L for Linezolid. The method proved to be precise and accurate and applicable for therapeutic drug monitoring and other pharmacokinetic studies. A robust and fast ultra‐performance liquid chromatography tandem mass spectrometry method for the simultaneous analysis of Meropenem, Cefepime, Ceftazidime, Piperacillin, Benzylpenicillin, Ampicillin, Flucloxacillin, Linezolid, and Sulfomethoxazole/Trimethoprim is developed and validated. Sample preparation consists of a simple protein precipitation, using 9 isotopically labeled internal standards, followed by dilution in water. The method is fast, precise and accurate. The method is suitable for therapeutic drug monitoring as well as for pharmacokinetic studies.