Vancomycin has been associated with acute kidney injury (AKI).A cute kidney injury (AKI) is a major contributor to patient morbidity and mortality in the hospital setting (1, 2). While the etiology of AKI is multifactorial, many cases among hospital patients are related to medication exposure (2). Not surprisingly, the risk of drug-induced AKI is highest among critically ill, hospitalized patients (3), who carry multiple risk factors for the development and progression of AKI. Vancomycin, the antibiotic most frequently administered in the hospital setting (4), has been implicated as a cause of AKI in a number of clinical (5-7) and animal (8-10) studies. Among the clinical studies, the incidence of vancomycin-induced AKI has been associated with higher doses of vancomycin (11, 12), increasing numbers of vancomycin doses (12), and elevated trough concentrations (7, 13).While a number of clinical studies have shown that more intensive vancomycin dosing regimens are associated with an increased risk of AKI, these studies could only suggest an association with kidney injury. As these studies were largely observational in nature, it is difficult to discern if the association was reflective of a true effect or was biased due to confounders. For example, patient confounder factors, such as severity of illness, residence in an intensive care unit, and concurrent receipt of nephrotoxins, may influence the vancomycin exposure-response profile that best predicts clinical AKI.Animal systems are ideally suited to define exposure-response relationships, as they provide flexibility to titrate dosing groups and minimize the influence of external covariates on the observed results. To date, animal models of AKI have confirmed that vancomycin is a nephrotoxin. Dose-ranging studies have revealed that an increase in the vancomycin dose and an increase in the duration of treatment in rats are associated with increases in histopathological damage and elevations in novel urinary biomarkers of AKI (8-10). However, a prospectively derived ex-

Vancomycin has been associated with acute kidney injury in preclinical and clinical settings; however, the precise exposure profiles associated with vancomycin-induced acute kidney injury have not been defined. We sought to determine pharmacokinetic/pharmacodynamics indices associated with the development of acute kidney injury using sensitive urinary biomarkers. Male Sprague-Dawley rats received clinical-grade vancomycin or normal saline as an intraperitoneal injection. Total daily doses between 0 and 400 mg/kg of body weight were administered as a single dose or 2 divided doses over a 24-h period. At least five rats were utilized for each dosing protocol. A maximum of 8 plasma samples per rat were obtained, and urine was collected over the 24-h period. Kidney injury molecule-1 (KIM-1), clusterin, osteopontin, cystatin C, and neutrophil gelatinase-associated lipocalin levels were determined using Milliplex multianalyte profiling rat kidney panels. Vancomycin plasma concentrations were determined via a validated high-performance liquid chromatography methodology. Pharmacokinetic analyses were conducted using the Pmetrics package for R. Bayesian maximal concentrations were generated and utilized to calculate the 24-h area under the concentration-time curve (AUC), the maximum concentration (), and the minimum concentration. Spearman's rank correlation coefficient ( ) was used to assess the correlations between exposure parameters, biomarkers, and histopathological damage. Forty-seven rats contributed pharmacokinetic and toxicodynamic data. KIM-1 was the only urinary biomarker that correlated with both composite histopathological damage ( = 0.348, = 0.017) and proximal tubule damage ( = 0.342, = 0.019). The vancomycin AUC and were most predictive of increases in KIM-1 levels ( = 0.438 and = 0.002 for AUC and = 0.451 and = 0.002 for). Novel urinary biomarkers demonstrate that kidney injury can occur within 24 h of vancomycin exposure as a function of either AUC or .

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Urinary biomarkers are superior to serum creatinine for defining onset and extent of kidney injury. This study classifies the temporal predictive ability of biomarkers for vancomycin-induced kidney injury (VIKI) as defined by histopathologic damage. Male Sprague-Dawley rats (n = 125) were randomized to receive 150 to 400 mg/kg of body weight/day vancomycin via once or twice daily intraperitoneal injection over 1, 3, or 6 days. Urine was collected once during the 24 h prior to euthanasia or twice for rats treated for 6 days. Receiver operating characteristic (ROC) curves were employed to assess the urinary biomarker performances of kidney injury molecule 1 (KIM-1), clusterin, osteopontin (OPN), cystatin C, and neutrophil gelatinase-associated lipocalin (NGAL) to predict histopathologically defined VIKI (using a national standard pathological assessment scheme from hematoxylin and eosin stained kidneys). Urinary KIM-1, clusterin, and OPN outperformed cystatin C and NGAL with regard to sensitivity and specificity. For the earliest injury, urinary KIM-1 (area under the receiver operating characteristic curve [AUC], 0.662; P < 0.001) and clusterin (AUC, 0.706; P < 0.001) were the most sensitive for predicting even low-level histopathologic damage at 24 h compared to NGAL. KIM-1 and clusterin are the earliest and most sensitive predictors of VIKI. As injury progresses, KIM-1, clusterin, and OPN best define the extent of damage.

Polymyxin B remains an antibiotic of last resort because of its toxicities. Although newer therapies are becoming available, it is anticipated that resistance to these agents will continue to emerge, and understanding the safest and most efficacious manner to deliver polymyxin B will remain highly important. Recent data have demonstrated that polymyxin B may be less nephrotoxic than colistin. Pharmacokinetically, polymyxin B is primarily eliminated via non-renal pathways, and most do not recommend adjusting the dose for renal impairment. However, some recent studies suggest a weak relationship between polymyxin B clearance and patient creatinine clearance. This review article will describe the clinical pharmacokinetics of polymyxin B and address relevant issues in chemistry and assays available.

Background Vancomycin and piperacillin/tazobactam are reported in clinical studies to increase acute kidney injury (AKI). However, no clinical study has demonstrated synergistic toxicity, only that serum creatinine increases. Objectives To clarify the potential for synergistic toxicity between vancomycin, piperacillin/tazobactam and vancomycin + piperacillin/tazobactam treatments by quantifying kidney injury in a translational rat model of AKI and using cell studies. Methods (i) Male Sprague–Dawley rats (n = 32) received saline, vancomycin 150 mg/kg/day intravenously, piperacillin/tazobactam 1400 mg/kg/day intraperitoneally or vancomycin + piperacillin/tazobactam for 3 days. Urinary biomarkers and histopathology were analysed. (ii) Cellular injury was assessed in NRK-52E cells using alamarBlue®. Results Urinary output increased from Day −1 to Day 1 with vancomycin but only after Day 2 for vancomycin + piperacillin/tazobactam-treated rats. Plasma creatinine was elevated from baseline with vancomycin by Day 2 and only by Day 4 for vancomycin + piperacillin/tazobactam. Urinary KIM-1 and clusterin were increased with vancomycin from Day 1 versus controls (P &lt; 0.001) and only on Day 3 with vancomycin + piperacillin/tazobactam (P &lt; 0.001, KIM-1; P &lt; 0.05, clusterin). The histopathology injury score was elevated only in the vancomycin group when compared with piperacillin/tazobactam as a control (P = 0.04) and generally not so with vancomycin + piperacillin/tazobactam. In NRK-52E cells, vancomycin induced cell death with high doses (IC50 48.76 mg/mL) but piperacillin/tazobactam did not, and vancomycin + piperacillin/tazobactam was similar to vancomycin. Conclusions All groups treated with vancomycin demonstrated AKI; however, vancomycin + piperacillin/tazobactam was not worse than vancomycin. Histopathology suggested that piperacillin/tazobactam did not worsen vancomycin-induced AKI and may even be protective.

Objectives To identify the pharmacokinetic (PK) and toxicodynamic (TD) relationship for vancomycin-induced kidney injury. Methods Male Sprague–Dawley rats received intravenous (iv) vancomycin. Doses ranging from 150 mg/kg/day to 400 mg/kg/day were administered as a single or twice-daily injection over 24 h (total protocol duration). Controls received iv saline. Plasma was sampled with up to eight samples in 24 h per rat. Twenty-four hour urine was collected and assayed for kidney injury molecule 1 (KIM-1), osteopontin and clusterin. Vancomycin in plasma was quantified via LC-MS/MS. PK analyses were conducted using Pmetrics for R. PK exposures during the first 24 h (i.e. AUC0–24h, Cmax 0–24h and Cmin 0–24h) were calculated. PK/TD relationships were assessed with Spearman’s rank coefficient (rs) and the best-fit mathematical model. Results PK/TD data were generated from 45 vancomycin-treated and 5 control rats. A two-compartment model fit the data well (Bayesian: observed versus predicted R2 = 0.97). Exposure–response relationships were found between AUC0–24h versus KIM-1 and osteopontin (R2 = 0.61 and 0.66) and Cmax 0–24h versus KIM-1 and osteopontin (R2 = 0.50 and 0.56) using a four-parameter Hill fit. Conversely, Cmin 0–24h was less predictive of KIM-1 and osteopontin (R2 = 0.46 and 0.53). A vancomycin AUC0–24h of 482.2 corresponded to a 90% of maximal rise in KIM-1. Conclusions Vancomycin-induced kidney injury as defined by urinary biomarkers is driven by vancomycin AUC or Cmax rather than Cmin. Further, an identified PK/TD target AUC0–24h of 482.2 mg·h/L may have direct relevance to human outcomes.

Vancomycin is a recommended therapy in multiple national guidelines. Despite the common use, there is a poor understanding of the mechanistic drivers and potential modifiers of vancomycin-mediated kidney injury. In this review, historic and contemporary rates of vancomycin-induced kidney injury (VIKI) are described, and toxicodynamic models and mechanisms of toxicity from preclinical studies are reviewed. Aside from known clinical covariates that worsen VIKI, preclinical models have demonstrated that various factors impact VIKI, including dose, route of administration, and thresholds for pharmacokinetic parameters. The degree of acute kidney injury (AKI) is greatest with the intravenous route and higher doses that produce larger maximal concentrations and areas under the concentration curve. Troughs (i.e., minimum concentrations) have less of an impact. Mechanistically, preclinical studies have identified that VIKI is a result of drug accumulation in proximal tubule cells, which triggers cellular oxidative stress and apoptosis. Yet, there are several gaps in the knowledge that may represent viable targets to make vancomycin therapy less toxic. Potential strategies include prolonging infusions and lowering maximal concentrations, administration of antioxidants, administering agents that decrease cellular accumulation, and reformulating vancomycin to alter the renal clearance mechanism. Based on preclinical models and mechanisms of toxicity, we propose potential strategies to lessen VIKI.