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.

Pharmacokinetics of ceftriaxone in patients undergoing continuous renal replacement therapy.

BACKGROUND: The duration of time for which the serum levels exceed the minimum inhibitory concentration (MIC) is an important pharmacokinetics (PK)/pharmacodynamics (PD) parameter correlating with efficacy for the antibiotic, ceftriaxone (CTRX). However, no reports exist regarding the PK or PD in patients undergoing continuous renal replacement therapy (CRRT). The purpose of this study was to examine the PK and safety of CTRX in patients undergoing CRRT in order to establish safer and more effective regimens. METHODS: CTRX (1 g once a day) was intravenously administered four or more times to nine patients undergoing CRRT. Blood was collected after administration to measure CTRX concentrations in serum and the filtration fraction of CRRT by high-performance liquid chromatography. In addition to calculating PK parameters from serum CTRX, we (a) estimated by simulation CTRX concentrations when the dose interval was extended to once every 2 or 3 days, (b) calculated CTRX clearance via CRRT from CTRX concentrations in the filtration fraction, and (c) assessed the safety of CTRX use. RESULTS: Total body clearance and the half-life of CTRX were 7.46 mL/min (mean) and 26.5 h, respectively, in patients undergoing CRRT. CTRX was found in the filtration fraction, and the estimated clearance by CRRT was about 70% of total body clearance. Simulations revealed that even when the dose interval is increased to 2 or 3 days, CTRX would retain its efficacy. CONCLUSIONS: Our findings suggest that, depending on the condition of patients undergoing CRRT, CTRX could be used safely against pathogens with a CTRX MIC ≤2 µg/mL, even when extending the dose interval.