Gwendolyn Pais

Evaluation of Vancomycin Exposures Associated with Elevations in Novel Urinary Biomarkers of Acute Kidney Injury in Vancomycin-Treated Rats

ABSTRACT Vancomycin has been associated with acute kidney injury (AKI). However, the pharmacokinetic/toxicodynamic relationship for AKI is not well defined. Allometrically scaled vancomycin exposures were used to assess the relationship between vancomycin exposure and AKI. Male Sprague-Dawley rats received clinical-grade vancomycin in normal saline (NS) as intraperitoneal (i.p.) injections for 24- to 72-h durations with doses ranging 0 to 200 mg/kg of body weight divided once or twice daily. Urine was collected over the protocols final 24 h. Renal histopathology was qualitatively scored. Urinary biomarkers (e.g., cystatin C, clusterin, kidney injury molecule 1 [KIM-1], osteopontin, lipocalin 2/neutrophil gelatinase-associated lipocalin 2) were assayed using a Luminex xMAP system. Plasma vancomycin concentrations were assayed by high-performance liquid chromatography with UV detection. A three-compartment vancomycin pharmacokinetic model was fit to the data with the Pmetrics package for R. The exposure-response in the first 24 h was evaluated using Spearmans nonparametric correlation coefficient (rs) values for the area under the concentration-time curve during the first 24 h (AUC0–24), the maximum concentration in plasma during the first 24 h (Cmax0–24), and the lowest (minimum) concentration in plasma after the dose closest to 24 h (Cmin0–24). A total of 52 rats received vancomycin (n = 42) or NS (n = 10). The strongest exposure-response correlations were observed between AUC0–24 and Cmax0–24 and urinary AKI biomarkers. Exposure-response correlations (rs values) for AUC0–24, Cmax0–24, and Cmin0–24 were 0.37, 0.39, and 0.22, respectively, for clusterin; 0.42, 0.45, and 0.26, respectively, for KIM-1; and 0.52, 0.55, and 0.42, respectively, for osteopontin. However, no differences in histopathological scores were observed. Optimal sampling times after administration of the i.p. dose were 0.25, 0.75, 2.75, and 8 h for the once-daily dosing schemes and 0.25, 1.25, 14.5, and 17.25 h for the twice-daily dosing schemes. Our observations suggest that AUC0–24 or Cmax0–24 correlates with increases in urinary AKI biomarkers.

Endothelin ETA receptor antagonist reverses naloxone-precipitated opioid withdrawal in mice

Long-term use of opioids for pain management results in rapid development of tolerance and dependence leading to severe withdrawal symptoms. We have previously demonstrated that endothelin-A (ETA) receptor antagonists potentiate opioid analgesia and eliminate analgesic tolerance. This study was designed to investigate the involvement of central ET mechanisms in opioid withdrawal. The effect of intracerebroventricular administration of ETA receptor antagonist BQ123 on morphine and oxycodone withdrawal was determined in male Swiss Webster mice. Opioid tolerance was induced and withdrawal was precipitated by the opioid antagonist naloxone. Expression of ETA and ETB receptors, nerve growth factor (NGF), and vascular endothelial growth factor was determined in the brain using Western blotting. BQ123 pretreatment reversed hypothermia and weight loss during withdrawal. BQ123 also reduced wet shakes, rearing behavior, and jumping behavior. No changes in expression of vascular endothelial growth factor, ETA receptors, and ETB receptors were observed during withdrawal. NGF expression was unaffected in morphine withdrawal but significantly decreased during oxycodone withdrawal. A decrease in NGF expression in oxycodone- but not in morphine-treated mice could be due to mechanistic differences in oxycodone and morphine. It is concluded that ETA receptor antagonists attenuate opioid-induced withdrawal symptoms.

Evaluation of liposomal nanocarriers loaded with ETB receptor agonist, IRL-1620, using cell-based assays

One common feature of most neurodegenerative diseases, including Alzheimers disease (AD) and stroke, is the death of neuronal cells. Neuronal cell death is associated with apoptosis, generation of reactive oxygen species and oxidative stress. Neuronal cell death pathways can be reversed by endothelin B receptor agonist, IRL-1620, which was found to enhance neuroprotection by promoting vascular and neuronal growth in a rodent stroke model. Previous studies conducted at our institution indicated that the treatment with IRL-1620 significantly improved neurological and motor function while reducing oxidative stress and overall infarct area. IRL-1620 is a hydrophilic, 15 amino acid peptide and has a molecular weight of 1820Da. In this study, we have encapsulated IRL-1620 in PEGylated liposomes in order to enhance its efficacy. Each batch of liposomes encapsulating IRL-1620 was evaluated for particle size, polydispersity index, and charge (zeta potential) over a period of time to determine their stability. A dose-response bar graph was plotted based on the effect of neuroprotection by free IRL-1620 on differentiated neuronal PC-12 cells. The 1nM concentration was found to have the highest cell viability. The liposomes loaded with IRL-1620 were tested on differentiated neuronal PC-12 cells for their neuroprotective ability against apoptosis caused by removal of nerve growth factor (NGF) against free (non-encapsulated) IRL-1620. The liposomal IRL-1620 was found to proliferate the growth of serum-deprived differentiated PC-12 cells significantly (p<0.0001). In the western blot analysis, the expression of the anti-apoptotic marker, BCL-2 was found to be increased, and that of pro-apoptotic marker, BAX was found to be decreased with liposomal IRL-1620. The effects were found to be independent of the NGF levels. Finally the free IRL-1620 was found to cause neuronal outgrowth equivalent to the 75ng/ml NGF treatment.

Doses, durations, and gender predict vancomycin-induced kidney injury in pre-clinical studies

BACKGROUND Although the exposure-dependent efficacy thresholds of vancomycin have been probed, less is known about acute kidney injury (AKI) thresholds for this drug. Sensitive urinary biomarkers, such as kidney injury molecule 1 (KIM-1), have shown high sensitivity and specificity for vancomycin-associated AKI. The aims of the study were to determine if there were dose-response curves with urinary KIM-1, and to evaluate the impact of therapy duration and sex on observed relationships. METHODS A systematic review was conducted via PubMed/MEDLINE. Data were compiled from preclinical studies that reported individual subject data for urinary KIM-1 concentrations, vancomycin dose (mg/kg), duration of treatment, and sex. Sigmoidal Hill-type models were fit to the individual dose-response data. RESULTS A total of 15 studies were identified, 6 of which reported vancomycin dose and KIM-1 data. Of these, three included individual animal-level data suitable for analysis. For all pooled rats, increasing total daily vancomycin doses displayed a dose-response curve with urinary KIM-1 concentrations (50% maximal toxic response=130.4 mg/kg/day). Dose-response curves were shifted left for females vs. males (P = 0.05) and for long (i.e. ≥7 days) vs. short (i.e. <4 days) duration of vancomycin therapy (P=0.02). CONCLUSIONS The collective findings demonstrate a clear dose-response relationship between vancomycin dose and AKI. As these analyses focused exclusively on dose-response relationships, additional preclinical data are needed to more clearly define vancomycin exposures that predict the onset of AKI.

High-Performance Liquid Chromatography Method for Rich Pharmacokinetic Sampling Schemes in Translational Rat Toxicity Models With Vancomycin.

A translational need exists to understand and predict vancomycin‐induced kidney toxicity. We describe: (i) a vancomycin high‐performance liquid chromatography (HPLC) method for rat plasma and kidney tissue homogenate; (ii) a rat pharmacokinetic (PK) study to demonstrate utility; and (iii) a catheter retention study to enable future preclinical studies. Rat plasma and pup kidney tissue homogenate were analyzed via HPLC for vancomycin concentrations ranging from 3–75 and 15.1–75.5 μg/mL, respectively, using a Kinetex Biphenyl column and gradient elution of water with 0.1% formic acid: acetonitrile (70:30 v/v). Sprague‐Dawley rats (n = 10) receiving 150 mg/kg of vancomycin intraperitoneally had plasma sampled for PK. Finally, a catheter retention study was performed on polyurethane catheters to assess adsorption. Precision was <6.1% for all intra‐assay and interassay HPLC measurements, with >96.3% analyte recovery. A two‐compartment model fit the data well, facilitating PK exposure estimates. Finally, vancomycin was heterogeneously retained by polyurethane catheters.

Correction for Rhodes et al., Evaluation of Vancomycin Exposures Associated with Elevations in Novel Urinary Biomarkers of Acute Kidney Injury in Vancomycin-Treated Rats

Nathaniel J. Rhodes,a,b Walter C. Prozialeck,c Thomas P. Lodise,d Natarajan Venkatesan,e* J. Nicholas O’Donnell,a Gwendolyn Pais,e Cameron Cluff,a Peter C. Lamar,c Michael N. Neely,f,g Anil Gulati,e Marc H. Scheetza,b Department of Pharmacy Practice, Chicago College of Pharmacy, Midwestern University, Downers Grove, Illinois, USAa; Department of Pharmacy, Northwestern Memorial Hospital, Chicago, Illinois, USAb; Department of Pharmacology, Chicago College of Osteopathic Medicine, Midwestern University, Downers Grove, Illinois, USAc; Department of Pharmacy Practice, Albany College of Pharmacy and Health Sciences, Albany, New York, USAd; Department of Pharmaceutical Sciences, Chicago College of Pharmacy, Midwestern University, Downers Grove, Illinois, USAe; University of Southern California, Keck School of Medicine, Los Angeles, California, USAf; Laboratory of Applied Pharmacokinetics and Bioinformatics (LAPKB), Childrens Hospital of Los Angeles Saban Research Institute, Los Angeles, California, USAg

24-Hour Pharmacokinetic Relationships for Vancomycin and Novel Urinary Biomarkers of Acute Kidney Injury.

ABSTRACT 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 a posteriori concentrations were generated and utilized to calculate the 24-h area under the concentration-time curve (AUC), the maximum concentration (Cmax), and the minimum concentration. Spearmans rank correlation coefficient (rs) 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 (rs = 0.348, P = 0.017) and proximal tubule damage (rs = 0.342, P = 0.019). The vancomycin AUC and Cmax were most predictive of increases in KIM-1 levels (rs = 0.438 and P = 0.002 for AUC and rs = 0.451 and P = 0.002 for Cmax). Novel urinary biomarkers demonstrate that kidney injury can occur within 24 h of vancomycin exposure as a function of either AUC or Cmax.

270: EFFECT OF TIDAL VOLUME ON LUNG INJURY IN RATS WITH LPS-INDUCED SEPTIC SHOCK

Crit Care Med 2016 • Volume 44 • Number 12 (Suppl.) patients are less likely to survive to discharge. We hypothesize that precipitating etiology of arrest may be a more important predictor of survival than age alone. Methods: We performed a retrospective review of an IHCA registry at a tertiary academic hospital from July 2007 to May 2016. Included were patients suffering IHCA for whom cardiopulmonary resuscitation was attempted. Arrest etiology was evaluated via a validated classification scheme containing 4 categories according to primary disease process that led directly to the arrest. Survival to discharge was the primary outcome. Neurologic status at discharge also was evaluated according to Cerebral Performance Category (score of 1-2 considered favorable). Results: A total of 967 index IHCA were identified. Mean age was 59 ± 17 years (range 16-99 years); 36% were female. Forty-four percent of arrests occurred out-of-ICU. Overall survival was 34%, and 27% of patients had a favorable neurologic outcome at discharge. Eighty-four percent had a non-shockable rhythm at time of arrest. Etiology of arrest was mixed: respiratory (n=332, 34%), neurological (n=24, 2.5%), circulatory (n=358, 37%), and dysrhythmias (n=253, 26%). Age was not significantly associated with survival (OR 1.00, 95% CI 0.99-1.01; p=.55) nor favorable neurologic outcome at discharge (OR 1.00, 95% CI 0.99-1.01; p=.74) in univariate models. In multivariable regression, the association between age and survival remained non-significant (OR 0.99, 95% CI 0.98-1.00; p=.10) after adjusting for arrest etiology and location. Both arrest etiology and location were independently associated with survival and favorable neurologic outcome. Conclusions: In our large single-center cohort, age did not predict survival nor neurologic outcome after IHCA. By contrast, arrest etiology predicted survival independent of age and arrest location. These findings may help individualize treatment recommendations, guided by patient-specific risk factors for each arrest etiology.