UHPLC–MS/MS method for simultaneous quantification of doripenem, meropenem, ciprofloxacin, levofloxacin, pazufloxacin, linezolid, and tedizolid in filtrate during continuous renal replacement therapy

Background Since severe infections frequently cause acute kidney injury (AKI), continuous renal replacement therapy (CRRT) is often initiated for regulation of inflammatory mediators and renal support. Thus, it is necessary to decide the antibiotic dosage considering the CRRT clearance in addition to residual renal function. Some of the hemofilters used in CRRT are known to adsorb antibiotics, and clearance of antibiotics may differ depending on the adsorptive characteristics of hemofilters. Although assay systems for blood and CRRT filtrate concentrations are required, no method for measuring antibiotics concentrations in filtrate has been reported. We developed a UHPLC–MS/MS method for simultaneous quantification of antibiotics commonly used in ICU, comprising carbapenems [doripenem (DRPM) and meropenem (MEPM)], quinolones [ciprofloxacin (CPFX), levofloxacin (LVFX) and pazufloxacin (PZFX)] and anti‐MRSA agents [linezolid (LZD), and tedizolid (TZD)] in CRRT filtrate samples. Methods Filtrate samples were pretreated by protein precipitation. The analytes were separated with an ACQUITY UHPLC CSH C18 column under a gradient mobile phase consisting of water and acetonitrile containing 0.1% formic acid and 2 mM ammonium formate. Results The method showed good linearity over wide ranges. Within‐batch and batch‐to‐batch accuracy and precision for each drug fulfilled the criteria of the US Food and Drug Administration guidance. The recovery rate was more than 87.20%. Matrix effect ranged from 99.57% to 115.60%. Recovery rate and matrix effect did not differ remarkably between quality control samples at different concentrations. Conclusion This is the first report of a simultaneous quantification method of multiple antibiotics in filtrate of CRRT circuit. Chromatograms for measurement of doripenem (DRPM), meropenem (MEPM), linezolid (LZD), tedizolid (TZD), ciprofloxacin (CPFX), levofloxacin (LVFX), and pazufloxacin (PZFX) in lower limit of quantitation (LLOQ) filtrate sample (left) compared with blank filtrate (right).