The current antibiotic treatment of periprosthetic joint infection (PJI) is optimized by measuring concentrations in plasma. However, it remains unclear whether effective concentrations of the antibiotics are reached at the site of PJI. Nonetheless, adequate target site concentrations are important to achieve effective eradication of the micro-organism. In order to determine the efficacy of cefuroxime and flucloxacillin in synovial fluid, synovial tissue and bone tissue in relation to the minimal inhibitory concentration (MIC) of the pathogen causing the PJI, we perform a pharmacokinetic/pharmacodynamic (PK/PD) study. Therefore, we aimed to develop validated analytical methods for analysis of cefuroxime and flucloxacillin in synovial fluid, synovial tissue and bone tissue. Blank samples of synovial fluid, synovial tissue and bone tissue were obtained by orthopedic surgeons during surgery. For validation the samples of each matrix were spiked with both cefuroxime and flucloxacillin. Synovial tissue and bone tissue was pulverized with a mikro-dismembrator. Samples were kept frozen at −20°C until analysis. After a sample preparation quantification of cefuroxime and flucloxacillin in each matrix was performed on the ultra-performance convergence chromatography-tandem mass spectrometry (UPC2-MS/MS). Stable-isotope-labeled meropenem-d6 served as internal standard. The linearity, limits of quantification, accuracy and precision and carry-over were determined for all methods separately. The methods were validated according to the European Medicine Agency (EMA) and Food and Drug Administration (FDA) guidelines on bioanalytical method validation.Aim
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