Preanalytical Stability of Piperacillin, Tazobactam, Meropenem, and Ceftazidime in Plasma and Whole Blood Using Liquid Chromatography–Tandem Mass Spectrometry

Abstract

Background: Therapeutic drug monitoring (TDM) is increasingly used to optimize the dosing of beta-lactam antibiotics in critically ill patients. However, beta-lactams are inherently unstable and degrade over time. Hence, patient samples need to be appropriately handled and stored before analysis to generate valid results for TDM. The appropriate handling and storage conditions are not established, with few and conflicting studies on the stability of beta-lactam antibiotics in clinical samples. The aim of this study was to assess the preanalytical stability of piperacillin, tazobactam, meropenem, and ceftazidime in human plasma and whole blood using a liquid chromatography–tandem mass spectrometry method for simultaneous quantification. Methods: A reverse phase liquid chromatography–tandem mass spectrometry method for the quantification of piperacillin, tazobactam, meropenem, and ceftazidime in plasma after protein precipitation was developed and validated. The preanalytical stability of these beta-lactams was assessed in EDTA- and citrate-anticoagulated plasma at 24, 4, and −20°C. The whole blood stability of the analytes in EDTA-anticoagulated tubes was assessed at 24°C. Stability was determined by nonlinear regression analysis defined by the lower limit of the 95th confidence interval of the time to 15% of degradation. Results: Based on the lower limit of the 95th confidence interval of the time to 15% of degradation, piperacillin, tazobactam, meropenem, and ceftazidime were stable in EDTA-anticoagulated plasma for at least 6 hours at 24°C, 3 days at 4°C, and 4 days at −20°C. Stability in EDTA- and citrate-anticoagulated plasma was similar. Stability in whole blood was similar to plasma at 24°C. Conclusions: Plasma samples for the TDM of piperacillin, tazobactam, meropenem, and ceftazidime should be processed within 6 hours if kept at room temperature and within 3 days if kept at 4°C. All long-term storage of samples should be at −80°C.

Molecular Adsorbent Recirculating System Therapy with Continuous Renal Replacement Therapy Enhanced Clearance of Piperacillin in a Pediatric Patient and Led to Failure to Attain Pharmacodynamic Targets

“…Residual blood was stored at 4°C for up to 4 days (median, 3 days) before processing. Stability of piperacillin at this temperature for 3–4 days has been demonstrated previously 9 and reproduced by our own group (data not shown). Blood was centrifuged (2060 g , 10–20°C, 10 min), and the supernatant was stored at −80°C until free concentrations were measured.…”

Demonstrating Feasibility of an Opportunistic Sampling Approach for Pharmacokinetic Studies of β‐Lactam Antibiotics in Critically Ill Children

“…These findings show stability for longer periods of time at 4°C than previous studies. Defining stability as less than 15% degradation, Mortensen and colleagues showed that piperacillin, tazobactam, meropenem, and ceftazidime were stable in whole blood and ethylenediaminetetraacetic acid (EDTA)‐anticoagulated plasma at 4°C for 3 days, 12 and Bugnon and colleagues observed cefepime stability in plasma for at least 12 hours at 4°C 14 . Another study showed decay of <15% of meropenem in plasma in 4 days at 6°C 26 .…”

“…For chromatographic assays, the Food and Drug Administration (FDA) defines stability as being ±15% of the original concentration 11 . Multiple studies have shown that various β‐lactam antibiotics, including piperacillin, cefepime, and meropenem, are stable at room temperature for only a few hours in whole blood or plasma, and some studies have shown β‐lactam stability for a few days at 4°C 9,10,12–14 . However, there is no agreement on the best practice for short‐term storage of beta‐lactam antibiotics to ensure stability.…”

Meropenem Stability in Human Plasma at −20 °C: Detailed Assessment of Degradation

“…Studies have reported that β-lactams show substantial degradation in plasma depending on the storage temperature and storage time [4][5][6]. For meropenem, significant degradation has been shown beyond 6 h at 24 • C or 3 days at 4 • C [7]. Hence, plasma samples should be processed and frozen as soon as possible.…”