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BACKGROUND - Recent studies in adults have found an incidence of acute kidney injury (AKI) in patients treated with a combination of vancomycin and piperacillin-tazobactam (TZP) that is greater than that expected with either medication alone. The purpose of this study was to determine whether combination therapy with vancomycin and TZP is associated with an incidence of AKI in pediatric patients higher than that in those on combination therapy with vancomycin and cefepime.
METHODS - We performed a retrospective single-center matched-cohort study of pediatric patients who received vancomycin in combination with TZP or cefepime between January 2015 and June 2016. The patients were matched according to chronic disease, age, sex, and number of concomitant nephrotoxic medications at the time of combination antibiotic therapy. The primary outcome was incidence of AKI. Secondary outcomes included differences between groups in time to AKI, resolution of AKI, and effect of vancomycin trough levels on the incidence of nephrotoxicity. Conditional logistic regression was used to compare categorical and continuous variables between treatment groups. Conditional Poisson regression was used to assess the association between AKI and treatment groups. Stratified log-rank tests and Cox proportional hazards models with shared frailty were used to compare the times to AKI according to treatment group.
RESULTS - Two hundred twenty-eight matched patients were included. AKI developed in 9 (7.9%) of 114 and 33 (28.9%) of 114 patients in the cefepime and TZP groups, respectively (P < .001). Type of combination therapy remained a significant predictor for AKI in multivariate conditional Poisson analysis in which adjustments were made for age, sex, use of concomitant nephrotoxins, and vancomycin dose (relative risk, 2.5 [95% confidence interval, 1.1-5.8]; P = .03). AKI developed almost 3 times sooner in the TZP group than in the cefepime group (hazard ratio, 2.9 [95% confidence interval, 1.3-6.1]; P = .006). Sensitivity analyses in which adjustment was made for antibiotic indication in addition to the aforementioned variables and excluding those with gastrointestinal infection revealed similar results.
CONCLUSION - Among hospitalized children at our institution, combination therapy with vancomycin and TZP was associated with an incidence of AKI higher than that associated with vancomycin and cefepime.
© The Author(s) 2018. Published by Oxford University Press on behalf of The Journal of the Pediatric Infectious Diseases Society. All rights reserved. For permissions, please e-mail: email@example.com.
BACKGROUND AND OBJECTIVES - Infection is the most common cause of death in severe AKI, but many patients receiving continuous RRT do not reach target antibiotic concentrations in plasma. Extended infusion of β-lactams is associated with improved target attainment in critically ill patients; thus, we hypothesized that extended infusion piperacillin-tazobactam would improve piperacillin target attainment compared with short infusion in patients receiving continuous RRT.
DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS - We conducted an institutional review board-approved observational cohort study of piperacillin-tazobactam pharmacokinetics and pharmacodynamics in critically ill patients receiving continuous venovenous hemodialysis and hemodiafiltration at three tertiary care hospitals between 2007 and 2015. Antibiotic concentrations in blood and/or dialysate samples were measured by liquid chromatography, and one- and two-compartment pharmacokinetic models were fitted to the data using nonlinear mixed effects regression. Target attainment for piperacillin was defined as achieving four times the minimum inhibitory concentration of 16 μg/ml for >50% of the dosing cycle. The probabilities of target attainment for a range of doses, frequencies, and infusion durations were estimated using a Monte Carlo simulation method. Target attainment was also examined as a function of patient weight and continuous RRT effluent rate.
RESULTS - Sixty-eight participants had data for analysis. Regardless of infusion duration, 6 g/d piperacillin was associated with ≤45% target attainment, whereas 12 g/d was associated with ≥95% target attainment. For 8 and 9 g/d, target attainment ranged between 68% and 85%. The probability of target attainment was lower at higher effluent rates and patient weights. For all doses, frequencies, patient weights, and continuous RRT effluent rates, extended infusion was associated with higher probability of target attainment compared with short infusion.
CONCLUSIONS - Extended infusions of piperacillin-tazobactam are associated with greater probability of target attainment in patients receiving continuous RRT.
Copyright © 2016 by the American Society of Nephrology.
BACKGROUND AND OBJECTIVES - Current recommendations for piperacillin-tazobactam dosing in patients receiving continuous renal replacement therapy originate from studies with relatively few patients and lower continuous renal replacement therapy doses than commonly used today. This study measured the pharmacokinetic and pharmacodynamic characteristics of piperacillin-tazobactam in patients treated with continuous renal replacement therapy using contemporary equipment and prescriptions.
DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS - A multicenter prospective observational study in the intensive care units of two academic medical centers was performed, enrolling patients with AKI or ESRD receiving piperacillin-tazobactam while being treated with continuous renal replacement therapy. Pregnant women, children, and patients with end stage liver disease were excluded from enrollment. Plasma and continuous renal replacement therapy effluent samples were analyzed for piperacillin and tazobactam levels using HPLC. Pharmacokinetic and pharmacodynamic parameters were calculated using standard equations. Multivariate analyses were used to examine the association of patient and continuous renal replacement therapy characteristics with piperacillin pharmacokinetic parameters.
RESULTS - Forty-two of fifty-five subjects enrolled had complete sampling. Volume of distribution (median=0.38 L/kg, intraquartile range=0.20 L/kg) and elimination rate constants (median=0.104 h(-1), intraquartile range=0.052 h(-1)) were highly variable, and clinical parameters could explain only a small fraction of the large variability in pharmacokinetic parameters. Probability of target attainment for piperacillin was 83% for total drug but only 77% when the unbound fraction was considered.
CONCLUSIONS - There is significant patient to patient variability in pharmacokinetic/pharmacodynamic parameters in patients receiving continuous renal replacement therapy. Many patients did not achieve pharmacodynamic targets, suggesting that therapeutic drug monitoring might optimize therapy.
Sepsis and multisystem organ failure are common diagnoses affecting nearly three-quarters of a million Americans annually. Infection is the leading cause of death in acute kidney injury, and the majority of critically ill patients who receive continuous dialysis also receive antibiotics. Dialysis equipment and prescriptions have gradually changed over time, raising concern that current drug dosing recommendations in the literature may result in underdosing of antibiotics. Our research group directed its attention toward antibiotic dosing strategies in patients with acute renal failure (ARF), and we sought data confirming that patients receiving continuous dialysis and antibiotics actually were achieving therapeutic plasma drug levels during treatment. In the course of those investigations, we explored "fast-track" strategies to estimate plasma drug concentrations. As most antimicrobial antibiotics are small molecules and should pass freely through modern high-flux hemodialyzer filters, we hypothesized that continuous renal replacement therapy (CRRT) effluent could be used as the medium for drug concentration measurement by reverse-phase high-pressure liquid chromatography (HPLC). Here we present the first data demonstrating this approach for piperacillin-tazobactam. Paired blood and dialysate trough-peak-trough samples were drawn from 19 patients receiving piperacillin-tazobactam and continuous venovenous hemodialysis (CVVHD). Total, free, and dialysate drug concentrations were measured by HPLC. Dialysate drug levels predicted plasma free drug levels well (r(2) = 0.91 and 0.92 for piperacillin and tazobactam, respectively) in all patients. These data suggest a strategy for therapeutic drug monitoring that minimizes blood loss from phlebotomy and simplifies analytic procedures.