Antibacterial agents (β-lactams, glycopeptides, aminoglycosides, macrolides, quinolones, and tetracyclines) belong to antimicrobial substances used for the treatment of infections. Despite their safety, therapeutic drug monitoring is recommended to optimize the treatment of patients with sepsis, as the pharmacokinetics of antimicrobial drugs is variable. In addition, hemoadsorbents are also used to reduce inflammation in septic patients, but they can also bind drugs. In the master's thesis we have developed a bioanalytical method for simultaneous determination of imipenem, amoxicillin, cefepime, meropenem, vancomycin and piperacillin concentration in bovine plasma. Plasma samples were prepared by protein precipitation with acetonitrile and extraction in dichloromethane. The analysis was performed using high-performance liquid chromatography with a C18 stationary phase and a mobile phase containing 0.5% H3PO4 (pH 7.0) and 0.5% H3PO4 (pH 3.0) with acetonitrile at a ratio of 3:1 (v/v). The flow rate of the mobile phase was 1.3 mL/min. Analytes were detected with a UV/VIS detector. The method was successfully validated according to the guidelines of the European Medicines Agency for the validation of bioanalytical methods. Based on validation parameters (intra-day and inter-day precision, accuracy, specificity), we confirm that the method is suitable for analyzing selected analytes in bovine plasma samples. The linear range for cefepime, piperacillin, and meropenem was defined in the concentration range of 1–75 µg/mL, while for vancomycin and amoxicillin, it was 1–100 µg/mL, and for imipenem, it was 2.5–100 µg/mL. Samples for analysis are stable for at least 12 hours at 5 °C in the autosampler. The validated method was successfully applied to determine the concentrations of selected antibiotics in an in vitro experiment involving the binding of antibiotics to the hemoadsorbent Cytosorb®. We found that the addition of Cytosorb® affects the concentration of selected antibiotics in bovine plasma, indicating the binding of antibiotics to the hemoadsorbent.
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