Vancomycin pharmacodynamics and survival in patients with methicillin-resistant Staphylococcus aureus-associated septic shock

Potential risk factors for early acute kidney injury in patients treated with vancomycin

PURPOSE

The acute kidney injury (AKI) onset owing to vancomycin (VCM) is reported that depend on the area under the blood concentration-time curve (AUC) and occur comparison early phase (early AKI). This study aimed to investigate the occurrence of early AKI in patients treated with VCM and new indicators to avoid early AKI.

METHODS

Adult patients who received VCM treatment for more than 4 days and whose trough values measured at least once on or after day 4 and serum creatinine before day 7 from the initiation of VCM administration between August 2021 and September 2022 at the Yamanashi Prefectural Central Hospital were enrolled. Early AKI (defined as AKI occurring within day 7 from VCM administration) and the association between each AUC (0-24, 24-48, 48-72, 0-48, 24-72, 0-72) were investigated. Furthermore, each AUC cut-off value for early AKI was calculated.

RESULT

In total, 164 patients were enrolled; early AKI developed in 21 patients and most frequently occurred on day 4. All stratified AUC were associated with early AKI development. The AUC cut-off values were AUC0-24: 470.8 μg/mL⋅h; AUC24-48: 473.0 μg/mL⋅h; AUC48-72: 489.7 μg/mL⋅h; AUC0-48: 910.2 μg/mL⋅h; AUC24-72: 1039.2 μg/mL⋅h; and AUC0-72: 1544.0 μg/mL⋅h.

CONCLUSION

The possibility of AKI development owing to the AUC accumulation of VCM was observed (accumulation toxicity). Concentration control through early-phase blood concentration measurements and a transition to AUC0-48 <910.2 μg/mL⋅h may reduce the early-phase AKI onset.

Antibiotic dose optimisation in the critically ill: targets, evidence and future strategies

PURPOSE OF REVIEW

To highlight the recent evidence for antibiotic pharmacokinetics and pharmacodynamics (PK/PD) in enhancing patient outcomes in sepsis and septic shock. We also summarise the limitations of available data and describe future directions for research to support translation of antibiotic dose optimisation to the clinical setting.

RECENT FINDINGS

Sepsis and septic shock are associated with poor outcomes and require antibiotic dose optimisation, mostly due to significantly altered pharmacokinetics. Many studies, including some randomised controlled trials have been conducted to measure the clinical outcome effects of antibiotic dose optimisation interventions including use of therapeutic drug monitoring. Current data support antibiotic dose optimisation for the critically ill. Further investigation is required to evolve more timely and robust precision antibiotic dose optimisation approaches, and to clearly quantify whether any clinical and health-economic benefits support expanded use of this treatment intervention.

SUMMARY

Antibiotic dose optimisation appears to improve outcomes in critically ill patients with sepsis and septic shock, however further research is required to quantify the level of benefit and develop a stronger knowledge of the role of new technologies to facilitate optimised dosing.

Evaluation of Vancomycin Dose Needed to Achieve 24-Hour Area Under the Concentration-Time Curve to Minimum Inhibitory Concentration Ratio Greater Than or Equal to 400 Using Pharmacometric Approaches in Pediatric Intensive Care Patients

OBJECTIVES

To investigate which independent factor(s) have an impact on the pharmacokinetics of vancomycin in critically ill children, develop an equation to predict the 24-hour area under the concentration-time curve from a trough concentration, and evaluate dosing regimens likely to achieve a 24-hour area under the concentration-time curve to minimum inhibitory concentration ratio (AUC24/MIC) greater than or equal to 400.

DESIGN

Prospective population pharmacokinetic study of vancomycin.

SETTING

Critically ill patients in quaternary care PICUs.

PATIENTS

Children 90 days old or older to younger than 18 years who received IV vancomycin treatment, irrespective of the indication for use, in the ICUs at the University of Maryland Children's Hospital and Texas Children's Hospital were enrolled.

INTERVENTIONS

Vancomycin was prescribed at doses and intervals chosen by the treating clinicians.

MEASUREMENTS AND MAIN RESULTS

A median of four serum levels of vancomycin per patient were collected along with other variables for up to 7 days following the first administration. These data were used to characterize vancomycin pharmacokinetics and evaluate the factors affecting the variability in achieving AUC24/MIC ratio greater than or equal to 400 in PICU patients who are not on extracorporeal therapy. A total of 302 children with a median age of 6.0 years were enrolled. A two-compartment model described the pharmacokinetics of vancomycin with the clearance of 2.76 L/hr for a typical patient weighing 20 kg. The glomerular filtration rate estimated using either the bedside Schwartz equation or the chronic kidney disease in children equation was the only statistically significant predictor of clearance among the variables evaluated, exhibiting equal predictive performance. The trough levels achieving AUC24/MIC = 400 were 5.6-10.0 μg/mL when MIC = 1 μg/mL. The target of AUC24/MIC greater than or equal to 400 was achieved in 60.4% and 36.5% with the typical dosing regimens of 15 mg/kg every 6 and 8 hours (q6h and q8h), respectively.

CONCLUSIONS

The pharmacokinetics of vancomycin in critically ill children were dependent on the estimated glomerular filtration rate only. Trough concentrations accurately predict AUC24. Typical pediatric vancomycin dosing regimens of 15 mg/kg q6h and q8h will often lead to AUC24/MIC under 400.

Is It Still Beneficial to Monitor the Trough Concentration of Vancomycin? A Quantitative Meta-Analysis of Nephrotoxicity and Efficacy

This study conducted a quantitative meta-analysis to investigate the association of vancomycin indicators, particularly area under the curve over 24 h (AUC24) and trough concentrations (Ctrough), and their relationship with both nephrotoxicity and efficacy. Literature research was performed in PubMed and Web of Science on vancomycin nephrotoxicity and efficacy in adult inpatients. Vancomycin Ctrough, AUC24, AUC24/minimum inhibitory concentration (MIC), nephrotoxicity evaluation and treatment outcomes were extracted. Logistic regression and Emax models were conducted, stratified by evaluation criterion for nephrotoxicity and primary outcomes for efficacy. Among 100 publications on nephrotoxicity, 29 focused on AUC24 and 97 on Ctrough, while of 74 publications on efficacy, 27 reported AUC24/MIC and 68 reported Ctrough. The logistic regression analysis indicated a significant association between nephrotoxicity and vancomycin Ctrough (odds ratio = 2.193; 95% CI 1.582-3.442, p < 0.001). The receiver operating characteristic curve had an area of 0.90, with a cut-off point of 14.55 mg/L. Additionally, 92.3% of the groups with a mean AUC24 within 400-600 mg·h/L showed a mean Ctrough of 10-20 mg/L. However, a subtle, non-statistically significant association was observed between the AUC24 and nephrotoxicity, as well as between AUC24/MIC and Ctrough concerning treatment outcomes. Our findings suggest that monitoring vancomycin Ctrough remains a beneficial and valuable approach to proactively identifying patients at risk of nephrotoxicity, particularly when Ctrough exceeds 15 mg/L. Ctrough can serve as a surrogate for AUC24 to some extent. However, no definitive cut-off values were identified for AUC24 concerning nephrotoxicity or for Ctrough and AUC24/MIC regarding efficacy.

In silico Evaluation of a Vancomycin Dosing Guideline Among Adults with Serious Infections

BACKGROUND

This study aimed to compare the achievement of pharmacokinetic-pharmacodynamic (PK-PD) exposure targets for vancomycin using a newly developed dosing guideline with product-information-based dosing in the treatment of adult patients with serious infections.

METHODS

In silico product-information- and guideline-based dosing simulations for vancomycin were performed across a range of doses and patient characteristics, including body weight, age, and renal function at 36-48 and 96 hours, using a pharmacokinetic model derived from a seriously ill patient population. The median simulated concentration and area under the 24-hour concentration-time curve (AUC 0-24 ) were used to measure predefined therapeutic, subtherapeutic, and toxicity PK-PD targets.

RESULTS

Ninety-six dosing simulations were performed. The pooled median trough concentration target with guideline-based dosing at 36 and 96 hours was achieved in 27.1% (13/48) and 8.3% (7/48) of simulations, respectively. The pooled median AUC 0-24 /minimum inhibitory concentration ratio with guideline-based dosing at 48 and 96 hours was attained in 39.6% (19/48) and 27.1% (13/48) of simulations, respectively. Guideline-based dosing simulations yielded improved trough target attainment compared with product-information-based dosing at 36 hours and significantly less subtherapeutic drug exposure. The toxicity threshold was exceeded in 52.1% (25/48) and 0% (0/48) for guideline- and product-information-information-based dosing, respectively ( P < 0.001).

CONCLUSIONS

A Critical care vancomycin dosing guideline appeared slightly more effective than standard dosing, as per product information, in achieving PK-PD exposure associated with an increased likelihood of effectiveness. In addition, this guideline significantly reduced the risk of subtherapeutic exposure. The risk of exceeding toxicity thresholds, however, was greater with the guideline, and further investigation is suggested to improve dosing accuracy and sensitivity.

Predicting the Area under the Plasma Concentration-Time Curve (AUC) for First Dose Vancomycin Using First-Order Pharmacokinetic Equations

To treat critically ill patients, early achievement of the target area under the plasma concentration-time curve/minimum inhibitory concentration (AUC/MIC) in the first 24 h is recommended. However, accurately calculating the AUC before steady state is an obstacle to this goal. A first-order pharmacokinetic equation to calculate vancomycin AUC after a first dose of vancomycin has never been studied. We sought to estimate AUC using two first-order pharmacokinetic equations, with different paired concentration time points, and to compare these to the actual first dose vancomycin AUC calculated by the linear-log trapezoid rule as a reference. The equations were validated using two independent intensive first dose vancomycin concentration time data sets, one from 10 adults and another from 14 children with severe infection. The equation with compensation for the alpha distribution phase using a first vancomycin serum concentration from 60 to 90 min and the second concentration from 240 to 300 min after the completed infusion showed good agreement and low bias of calculated AUC, with mean differences <5% and Lin's correlation coefficient >0.96. Moreover, it gave an excellent correlation with Pearson's r > 0.96. Estimating the first dose vancomycin AUC calculated using this first-order pharmacokinetic equation is both reliable and reproducible in clinical practice settings.

Clinical Approach to Nosocomial Bacterial Sepsis

Bacterial sepsis and septic shock are associated with a high mortality, and when clinically suspected, clinicians must initiate broad-spectrum antimicrobials within the first hour of diagnosis. Thorough review of prior cultures involving multidrug-resistant (MDR) pathogens along with other likely pathogens should be performed to provide an appropriate broad-spectrum empiric antibiotic coverage. The appropriate antibiotic loading dose followed by individualized modification of maintenance dose should be implemented based on the presence of hepatic or renal dysfunction. Use of procalcitonin is no longer recommended to determine need for initial antibacterial therapy and for de-escalation. Daily reevaluation of appropriateness of treatment is necessary based on the culture results and clinical response. All positive cultures should be carefully screened for possible contamination or colonization, which may not represent the true organism causing the sepsis. Culture negative sepsis accounts for one-half of all cases, and de-escalation of initial antibiotic regimen should be done gradually in these patients with close monitoring.

Review and evaluation of vancomycin dosing guidelines for obese individuals

INTRODUCTION

Vancomycin dosing decisions are informed by factors such as body weight and renal function. It is important to understand the impact of obesity on vancomycin pharmacokinetics and how this may influence dosing decisions. Vancomycin dosing guidelines use varied descriptors of body weight and renal function. There is uncertainty whether current dosing guidelines result in attainment of therapeutic targets in obese individuals.

AREAS COVERED

Literature was explored using PubMed, Embase and Google Scholar for articles from January 1980 to July 2021 regarding obesity-driven physiological changes, their influence on vancomycin pharmacokinetics and body size descriptors and renal function calculations in vancomycin dosing. Pharmacokinetic simulations reflective of international vancomycin dosing guidelines were conducted to evaluate the ability of using total, ideal and adjusted body weight, as well as Cockcroft-Gault and CKD-EPI equations to attain an area-under-the-curve to minimum inhibitory concentration ratio (AUC₂₄/MIC) target (400-650) in obese individuals.

EXPERT OPINION

Vancomycin pharmacokinetics in obese individuals remains debated. Guidelines that determine loading doses using total body weight, and maintenance doses adjusted based on renal function and adjusted body weight, may be most appropriate for obese individuals. Use of ideal body weight leads to subtherapeutic vancomycin exposure and underestimation of renal function.

Clinical Practice Guidelines for Therapeutic Drug Monitoring of Vancomycin in the Framework of Model-Informed Precision Dosing: A Consensus Review by the Japanese Society of Chemotherapy and the Japanese Society of Therapeutic Drug Monitoring

Background: To promote model-informed precision dosing (MIPD) for vancomycin (VCM), we developed statements for therapeutic drug monitoring (TDM). Methods: Ten clinical questions were selected. The committee conducted a systematic review and meta-analysis as well as clinical studies to establish recommendations for area under the concentration-time curve (AUC)-guided dosing. Results: AUC-guided dosing tended to more strongly decrease the risk of acute kidney injury (AKI) than trough-guided dosing, and a lower risk of treatment failure was demonstrated for higher AUC/minimum inhibitory concentration (MIC) ratios (cut-off of 400). Higher AUCs (cut-off of 600 μg·h/mL) significantly increased the risk of AKI. Although Bayesian estimation with two-point measurement was recommended, the trough concentration alone may be used in patients with mild infections in whom VCM was administered with q12h. To increase the concentration on days 1–2, the routine use of a loading dose is required. TDM on day 2 before steady state is reached should be considered to optimize the dose in patients with serious infections and a high risk of AKI. Conclusions: These VCM TDM guidelines provide recommendations based on MIPD to increase treatment response while preventing adverse effects.

Optimal Practice for Vancomycin Therapeutic Drug Monitoring: Position Statement From the Anti-infectives Committee of the International Association of Therapeutic Drug Monitoring and Clinical Toxicology

ABSTRACT

Individualization of vancomycin dosing based on therapeutic drug monitoring (TDM) data is known to improve patient outcomes compared with fixed or empirical dosing strategies. There is increasing evidence to support area-under-the-curve (AUC24)-guided TDM to inform vancomycin dosing decisions for patients receiving therapy for more than 48 hours. It is acknowledged that there may be institutional barriers to the implementation of AUC24-guided dosing, and additional effort is required to enable the transition from trough-based to AUC24-based strategies. Adequate documentation of sampling, correct storage and transport, accurate laboratory analysis, and pertinent data reporting are required to ensure appropriate interpretation of TDM data to guide vancomycin dosing recommendations. Ultimately, TDM data in the clinical context of the patient and their response to treatment should guide vancomycin therapy. Endorsed by the International Association of Therapeutic Drug Monitoring and Clinical Toxicology, the IATDMCT Anti-Infectives Committee, provides recommendations with respect to best clinical practice for vancomycin TDM.

Therapeutic Drug Monitoring of Antibiotics: Defining the Therapeutic Range

PURPOSE

In the present narrative review, the authors aimed to discuss the relationship between the pharmacokinetic/pharmacodynamic (PK/PD) of antibiotics and clinical response (including efficacy and toxicity). In addition, this review describes how this relationship can be applied to define the therapeutic range of a particular antibiotic (or antibiotic class) for therapeutic drug monitoring (TDM).

METHODS

Relevant clinical studies that examined the relationship between PK/PD of antibiotics and clinical response (efficacy and response) were reviewed. The review (performed for studies published in English up to September 2021) assessed only commonly used antibiotics (or antibiotic classes), including aminoglycosides, beta-lactam antibiotics, daptomycin, fluoroquinolones, glycopeptides (teicoplanin and vancomycin), and linezolid. The best currently available evidence was used to define the therapeutic range for these antibiotics.

RESULTS

The therapeutic range associated with maximal clinical efficacy and minimal toxicity is available for commonly used antibiotics, and these values can be implemented when TDM for antibiotics is performed. Additional data are needed to clarify the relationship between PK/PD indices and the development of antibiotic resistance.

CONCLUSIONS

TDM should only be regarded as a means to achieve the main goal of providing safe and effective antibiotic therapy for all patients. The next critical step is to define exposures that can prevent the development of antibiotic resistance and include these exposures as therapeutic drug monitoring targets.

A personalised approach to antibiotic pharmacokinetics and pharmacodynamics in critically ill patients

Critically ill patients admitted to intensive care unit (ICU) with severe infections, or those who develop nosocomial infections, have poor outcomes with substantial morbidity and mortality. Such patients commonly have suboptimal antibiotic exposures at routinely used antibiotic doses related to an increased volume of distribution and altered clearance due to their underlying altered physiology. Furthermore, the use of extracorporeal devices such as renal replacement therapy and extracorporeal membrane oxygenation in these group of patients also has the potential to alter in vivo drug concentrations. Moreover, ICU patients are likely to be infected with less-susceptible pathogens. Therefore, one potential contributing cause to the poor outcomes observed in critically ill patients may be related to subtherapeutic antibiotic exposures. Newer concepts include the clinician considering optimised dosing based on a blood antibiotic exposure defined by pharmacokinetic modelling and therapeutic drug monitoring, combined with a knowledge of the antibiotic penetration into the site of infection, thereby achieving optimal bacterial killing. Such optimised dosing is likely to improve patient outcomes. The aim of this review is to highlight key aspects of antibiotic pharmacokinetics and pharmacodynamics (PK/PD) in critically ill patients and provide a PK/PD approach to tailor antibiotic dosing to the individual patient.

Association of vancomycin trough concentration on the treatment outcome of patients with bacteremia caused by Enterococcus species

BACKGROUND

Pharmacokinetic-pharmacodynamic (PK/PD) targets of vancomycin therapy have been recognized for methicillin-resistant Staphylococcus aureus infections but not for other gram-positive bacterial infections. Therefore, we investigated whether vancomycin concentration targets such as the trough level and ratio of the area under the curve to minimum inhibitory concentration (AUC/MIC) are associated with the treatment outcome in enterococcal bacteremia.

METHODS

A retrospective cohort analysis enrolled patients with bacteremia caused by vancomycin-susceptible Enterococcus faecium and Enterococcus faecalis who were treated with vancomycin from January 2007 to December 2017 at a tertiary hospital located in Seoul, South Korea. Patients without vancomycin concentrations were excluded from the study. The primary outcome was 28-day all-cause mortality.

RESULTS

A total of 37 patients were enrolled-26 with E. faecium infection and 11 with E. faecalis infection. The 28-day all-cause mortality rate was 21.6 %. In univariate analysis, vancomycin trough level (≤ 15 µg/mL; p = 0.042), age (p = 0.044), and septic shock (p = 0.049) were associated with 28-day mortality but not AUC24/MIC (> 389; p = 0.479). In multivariate analysis, vancomycin trough concentration (≤ 15 µg/mL; p = 0.041) and younger age (p = 0.031) were associated with 28-day mortality in patients with enterococcal bacteremia.

CONCLUSIONS

In this study, a vancomycin trough level of 15 µg/mL or lower was associated with 28-day mortality in enterococcal bacteremia. However, relatively large prospective studies are needed to examine the efficacy of vancomycin PK/PD parameters in patients with enterococcal bacteremia.

Therapeutic Drug Monitoring of Vancomycin in Adult Patients with Methicillin-Resistant Staphylococcus aureus Bacteremia or Pneumonia

Background

Vancomycin remains widely used for methicillin-resistant Staphylococcus aureus (MRSA) infections; however, treatment failure rates up to 50% have been reported. At the authors' institution, monitoring of trough concentration is the standard of care for therapeutic drug monitoring of vancomycin. New guidelines support use of the ratio of 24-hour area under the concentration-time curve to minimum inhibitory concentration (AUC₂₄/MIC) as the pharmacodynamic index most likely to predict outcomes in patients with MRSA-associated infections.

Objectives

To determine the discordance rate between trough levels and AUC₂₄/MIC values and how treatment failure and nephrotoxicity outcomes compare between those achieving and not achieving their pharmacodynamic targets.

Methods

This retrospective cohort study involved patients with MRSA bacteremia or pneumonia admitted to the study hospital between March 1, 2014, and December 31, 2018, and treated with vancomycin. Data for trough concentrations were collected, and minimum concentrations (C _min) were extrapolated. The AUC₂₄/MIC values were determined using validated population pharmacokinetic models. The C _min and AUC₂₄/MIC values were characterized as below, within, or above pharmacodynamic targets (15-20 mg/L and 400-600, respectively). Discordance was defined as any instance where a patient's paired C _min and AUC₂₄/MIC values fell in different ranges (i.e., below, within, or above) relative to the target ranges. Predictors of treatment failure and nephrotoxicity were determined using logistic regression.

Results

A total of 128 patients were included in the analyses. Of these, 73 (57%) received an initial vancomycin dose less than 15 mg/kg. The discordance rate between C _min and AUC₂₄/MIC values was 21% (27/128). Rates of treatment failure and nephrotoxicity were 34% (43/128) and 18% (23/128), respectively. No clinical variables were found to predict discordance. Logistic regression identified initiation of vancomycin after a positive culture result (odds ratio [OR] 4.41, 95% confidence interval [CI] 1.36-14.3) and achievement of target AUC₂₄/MIC after 4 days (OR 3.48, 95% CI 1.39-8.70) as modifiable predictors of treatment failure.

Conclusions

The relationship between vancomycin monitoring and outcome is likely confounded by inadequate empiric or initial dosing. Before any modification of practice with respect to vancomycin monitoring, empiric vancomycin dosing should be optimized.

Optimizing Antimicrobial Drug Dosing in Critically Ill Patients

A fundamental step in the successful management of sepsis and septic shock is early empiric antimicrobial therapy. However, for this to be effective, several decisions must be addressed simultaneously: (1) antimicrobial choices should be adequate, covering the most probable pathogens; (2) they should be administered in the appropriate dose, (3) by the correct route, and (4) using the correct mode of administration to achieve successful concentration at the infection site. In critically ill patients, antimicrobial dosing is a common challenge and a frequent source of errors, since these patients present deranged pharmacokinetics, namely increased volume of distribution and altered drug clearance, which either increased or decreased. Moreover, the clinical condition of these patients changes markedly over time, either improving or deteriorating. The consequent impact on drug pharmacokinetics further complicates the selection of correct drug schedules and dosing during the course of therapy. In recent years, the knowledge of pharmacokinetics and pharmacodynamics, drug dosing, therapeutic drug monitoring, and antimicrobial resistance in the critically ill patients has greatly improved, fostering strategies to optimize therapeutic efficacy and to reduce toxicity and adverse events. Nonetheless, delivering adequate and appropriate antimicrobial therapy is still a challenge, since pathogen resistance continues to rise, and new therapeutic agents remain scarce. We aim to review the available literature to assess the challenges, impact, and tools to optimize individualization of antimicrobial dosing to maximize exposure and effectiveness in critically ill patients.

Retrospective multicentre matched cohort study comparing safety and efficacy outcomes of intermittent-infusion versus continuous-infusion vancomycin

BACKGROUND

Patients with good renal function receiving intermittent-infusion vancomycin (IIV) may require total daily doses ≥4 g to achieve trough concentrations of 15-20 mg/L, increasing the risk of vancomycin-associated nephrotoxicity. Continuous-infusion vancomycin (CIV) may be associated with a lower risk of vancomycin-associated nephrotoxicity compared with IIV, but studies comparing safety of both dosing strategies are lacking.

OBJECTIVES

To compare the risk of nephrotoxicity with CIV versus IIV when target concentration ranges were the same with both dosing modalities.

METHODS

A retrospective multicentre matched cohort study of admitted patients between 1 January 2010 and 31 December 2016 was completed. Adult patients who received ≥48 h of vancomycin with at least one steady-state vancomycin concentration were eligible. The primary outcome was to compare the rates of nephrotoxic risk and renal injury, defined by the RIFLE criteria, between CIV and IIV.

RESULTS

Of 2136 patients who received vancomycin during the study period, 146 CIV patients were eligible and matched to 146 IIV patients. After adjustment of potential confounders, CIV was found to have a lower odds of developing nephrotoxic risk (OR 0.42, 95% CI 0.21-0.98, P = 0.025) and renal injury (OR 0.19, 95% CI 0.05-0.59, P = 0.004).

CONCLUSIONS

CIV is associated with a lower odds of nephrotoxicity compared with IIV when targeting the same concentration range and should be an alternative dosing strategy for patients who will receive prolonged therapy or require >4 g/day to achieve therapeutic levels.

The Effect of Renal Replacement Therapy and Antibiotic Dose on Antibiotic Concentrations in Critically Ill Patients: Data From the Multinational Sampling Antibiotics in Renal Replacement Therapy Study

BACKGROUND

The optimal dosing of antibiotics in critically ill patients receiving renal replacement therapy (RRT) remains unclear. In this study, we describe the variability in RRT techniques and antibiotic dosing in critically ill patients receiving RRT and relate observed trough antibiotic concentrations to optimal targets.

METHODS

We performed a prospective, observational, multinational, pharmacokinetic study in 29 intensive care units from 14 countries. We collected demographic, clinical, and RRT data. We measured trough antibiotic concentrations of meropenem, piperacillin-tazobactam, and vancomycin and related them to high- and low-target trough concentrations.

RESULTS

We studied 381 patients and obtained 508 trough antibiotic concentrations. There was wide variability (4-8-fold) in antibiotic dosing regimens, RRT prescription, and estimated endogenous renal function. The overall median estimated total renal clearance (eTRCL) was 50 mL/minute (interquartile range [IQR], 35-65) and higher eTRCL was associated with lower trough concentrations for all antibiotics (P < .05). The median (IQR) trough concentration for meropenem was 12.1 mg/L (7.9-18.8), piperacillin was 78.6 mg/L (49.5-127.3), tazobactam was 9.5 mg/L (6.3-14.2), and vancomycin was 14.3 mg/L (11.6-21.8). Trough concentrations failed to meet optimal higher limits in 26%, 36%, and 72% and optimal lower limits in 4%, 4%, and 55% of patients for meropenem, piperacillin, and vancomycin, respectively.

CONCLUSIONS

In critically ill patients treated with RRT, antibiotic dosing regimens, RRT prescription, and eTRCL varied markedly and resulted in highly variable antibiotic concentrations that failed to meet therapeutic targets in many patients.

The impact of continuous renal replacement therapy on antibiotic pharmacokinetics in critically ill patients

Introduction: Mortality due to severe infections in critically ill patients undergoing continuous renal replacement therapy (CRRT) remains high. Nevertheless, rapid administration of adequate antibiotic therapy can improve survival. Delivering optimized antibiotic therapy can be a challenge, as standard drug regimens often result in insufficient or excessive serum concentrations due to significant changes in the volume of distribution and/or drug clearance in these patients. Insufficient drug concentrations can be responsible for therapeutic failure and death, while excessive concentrations can cause toxic adverse events.Areas covered: We performed a narrative review of the impact of CRRT on the pharmacokinetics of the most frequently used antibiotics in critically ill patients. We have provided explanations for the changes in the PKs of antibiotics observed and suggestions to optimize dosage regimens in these patients.Expert opinion: Despite considerable efforts to identify optimal antibiotic dosage regimens for critically ill patients receiving CRRT, adequate target achievement remains too low for hydrophilic antibiotics in many patients. Whenever possible, individualized therapy based on results from therapeutic drug monitoring must be given to avoid undertreatment or toxicity.

An evaluation on the association of vancomycin trough concentration with mortality in critically ill patients: A multicenter retrospective study

To determine the impact of initial vancomycin trough concentration (VTC) on mortality in adult patients in the intensive care unit (ICU) undergoing vancomycin therapy. During their first ICU stay, patients with initial VTC records after vancomycin treatment were recruited from the eICU Collaborative Research Database to this multicenter retrospective cohort study, and classified into four groups according to VTC: less than 10, 10–15, 15–20, and greater than 20 mg/L. Multivariable logistic regression and sensitivity analyses were performed to explore the association of VTC, as a continuous and categorical variable, with mortality. This study enrolled 7220 patients from 335 different ICUs at 208 hospitals. Multivariable logistic regression models indicated that VTC was positively correlated with ICU (odds ratio [OR], 1.028, 95% confidence interval [CI], 1.019–1.037) and hospital (OR 1.028, 95% CI, 1.020–1.036) mortalities. Moreover, compared with VTC less than 10 mg/L, VTCs of 10–15, 15–20, and greater than 20 mg/L were associated with a higher risk of ICU mortality (OR, 1.330, 95% CI, 1.070–1.653; OR, 1.596, 95% CI, 1.265–2.015; abd OR, 1.875, 95% CI, 1.491–2.357, respectively), and VTCs of 15–20 and greater than 20 mg/L were also correlated with increased hospital mortality (OR, 1.482, 95% CI, 1.225–1.793; and OR, 1.831, 95% CI, 1.517–2.210, respectively). Similar results persisted in patients with different Acute Physiology and Chronic Health Evaluation Ⅳ scores, creatinine clearance levels, ages, and body mass indexes. Our findings indicated a potential relationship of initial VTC with ICU and hospital mortalities in patients in the ICU. However, due to the retrospective nature of this study, future prospective studies or randomized controlled trials are needed to validate those results.

AUCs and 123s: a critical appraisal of vancomycin therapeutic drug monitoring in paediatrics

The revised vancomycin guidelines recommend implementing AUC24-based therapeutic drug monitoring (TDM) using Bayesian methods in both adults and paediatrics. The motivation for this change was accumulating evidence showing aggressive dosing to achieve high troughs, as recommended in the first guidelines for adults and extrapolated to paediatrics, is associated with increased nephrotoxicity without improving clinical outcomes. AUC24-based TDM requires substantial resources that may need to be diverted from other valuable interventions. It can therefore be justified only after certain assumptions are shown to be true: (i) there is a clear relationship between vancomycin efficacy and/or toxicity and the proposed therapeutic range; and (ii) maintaining exposure within the target range with AUC24-based TDM improves clinical outcomes and/or decreases toxicity. In this review, we critically appraise the scientific basis for these assumptions. We find studies evaluating the relationship between vancomycin AUC24/MIC and efficacy in adults and children do not offer strong support for the recommended lower limit of the proposed therapeutic range (i.e. AUC24/MIC ≥400). Nephrotoxicity in children increases in a stepwise manner along the vancomycin exposure continuum but it is unclear if one parameter (AUC24 versus trough) is a superior predictor. Overall, evidence in children suggests good-to-excellent correlation between AUC24 and trough. Most importantly, there is no convincing evidence that the method of vancomycin TDM has a causal role in improving efficacy or reducing toxicity. These findings question the need to transition to resource-intensive AUC24-based TDM over retaining trough-based TDM with lower targets to minimize nephrotoxicity in paediatrics.

The monitoring of vancomycin: a systematic review and meta-analyses of area under the concentration-time curve-guided dosing and trough-guided dosing

Background

This systematic review and meta-analysis explored the relationship between vancomycin (VCM) monitoring strategies and VCM effectiveness and safety.

Methods

We conducted our analysis using the MEDLINE, Web of Sciences, and Cochrane Register of Controlled Trials electronic databases searched on August 9, 2020. We calculated odds ratios (ORs) and 95% confidence intervals (CIs).

Results

Adult patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia with VCM trough concentrations ≥15 μg/mL had significantly lower treatment failure rates (OR 0.63, 95% CI 0.47–0.85). The incidence of acute kidney injury (AKI) increased with increased trough concentrations and was significantly higher for trough concentrations ≥20 μg/mL compared to those at 15–20 μg/mL (OR 2.39, 95% CI 1.78–3.20). Analysis of the target area under the curve/minimum inhibitory concentration ratios (AUC/MIC) showed significantly lower treatment failure rates for high AUC/MIC (cut-off 400 ± 15%) (OR 0.28, 95% CI 0.18–0.45). The safety analysis revealed that high AUC value (cut-off 600 ± 15%) significantly increased the risk of AKI (OR 2.10, 95% CI 1.13–3.89). Our meta-analysis of differences in monitoring strategies included four studies. The incidence of AKI tended to be lower in AUC-guided monitoring than in trough-guided monitoring (OR 0.54, 95% CI 0.28–1.01); however, it was not significant in the analysis of mortality.

Conclusions

We identified VCM trough concentrations and AUC values that correlated with effectiveness and safety. Furthermore, compared to trough-guided monitoring, AUC-guided monitoring showed potential for decreasing nephrotoxicity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-05858-6.

Vancomycin Serum Concentration after 48 h of Administration: A 3-Years Survey in an Intensive Care Unit

The present study assessed the proportion of intensive care unit (ICU) patients who had a vancomycin serum concentration between 20 and 25 mg/L after 24–48 h of intravenous vancomycin administration. From 2016 to 2018, adult ICU patients with vancomycin continuous infusion (CI) for any indication were included. The primary outcome was the proportion of patients with a first-available vancomycin serum concentration between 20–25 mg/L at 24 h (D2) or 48 h (D3). Of 3894 admitted ICU patients, 179 were included. A median loading dose of 15.6 (interquartile range (IQR) = (12.5–20.8) mg/kg) was given in 151/179 patients (84%). The median daily doses of vancomycin infusion for D1 and D2 were 2000 [(IQR (1600–2000)) and 2000 (IQR (2000–2500)) mg/d], respectively. The median duration of treatment was 4 (2–7) days. At D2 or D3, the median value of first serum vancomycin concentration was 19.8 (IQR (16.0–25.1)) with serum vancomycin concentration between 20–25 mg/L reported in 43 patients (24%). Time spent in the ICU before vancomycin initiation was the only risk factor of non-therapeutic concentration at D2 or D3. Acute kidney injury occurred significantly more when vancomycin concentration was supra therapeutic at D2 or D3. At D28, 44 (26%) patients had died. These results emphasize the need of appropriate loading dose and regular monitoring to improve vancomycin efficacy and avoid renal toxicity.

Antimicrobial Therapy in Septic Shock Is Conservative During Resuscitation and Maintenance Phases

Background: Maximal dosing of early antimicrobials with high loading and maintenance doses may optimize pharmacokinetic parameters to achieve and maintain therapeutic concentrations at the site of infection in septic shock. Little is known about the current practice of early antimicrobial dosing in septic shock. Objective: To characterize early antimicrobial dosing in patients in the resuscitation phase of septic shock. Methods: This retrospective cohort study included patients admitted to the medical intensive care unit (ICU) with septic shock. The primary outcome was the percentage of early antibiotic orders that were maximal or conservative during the resuscitation (0 to 48 hours) phase based on predefined dosing criteria. The secondary outcomes were the correlations of different dosing strategies on hospital length of stay (LOS), ICU LOS, and hospital mortality. Results: This study evaluated 161 patients and 692 antibiotic orders; 504 (72.8%) of the orders during the resuscitation phase were conservative. There were no differences in mortality (odds ratio = 0.66; 95% confidence interval = 0.35-1.25; P = .20), hospital LOS (median = 20 [interquartile range (IQR) = 10-34] vs 19 [IQR = 11-32] days; P = .93), or ICU LOS (median = 8 [IQR = 5-16] vs 9 [IQR = 5-15] days; P = .63) between maximal and conservative dosing groups, respectively, in the resuscitation phase. Limitations of this study included the use of institution-specific antimicrobial dosing guidelines and its retrospective nature. Conclusions: Early antibiotic dosing is conservative for a majority of patients in septic shock. Future studies are needed to evaluate the impact of dosing strategy on patient-centered outcomes in septic shock.

Development of Vancomycin Dose Individualization Strategy by Bayesian Prediction in Patients Receiving Continuous Renal Replacement Therapy

PURPOSE

Vancomycin (VCM) concentration is often out of therapeutic range (10-20 μg/ml) in patients receiving continuous renal replacement therapy (CRRT). The purposes of this study were to develop a practical VCM population pharmacokinetic (PPK) model and to evaluate the potential of Bayesian prediction-based therapeutic drug monitoring (Bayes-TDM) in VCM dose individualization for patients receiving CRRT.

METHODS

We developed a VCM PPK model using 80 therapeutic concentrations in 17 patients receiving CRRT. Bayes-TDM with the VCM PPK model was evaluated in 23 patients after PPK modeling.

RESULTS

We identified the covariates reduced urine output (RUO, <0.5 ml/kg/h) and effluent flow rate of CRRT for the VCM PPK model. The mean VCM non CRRT clearance (CL_nonCRRT) was 2.12 l/h. RUO lowered CL_nonCRRT to 0.34 l/h. The volume of distribution was 91.3 l/70 kg. The target concentration attainment rate by Bayes-TDM was higher (87.0%) than that by the PPK modeling period (53.8%, P = 0.046). The variance of the second measured concentrations by the Bayes-TDM was lower (11.5, standard deviation: 3.4 μg/ml) than that by the PPK modeling period (50.5, standard deviation: 7.1 μg/ml, P = 0.003).

CONCLUSIONS

Bayes-TDM could be a useful tool for VCM dose individualization in patients receiving CRRT.

Antimicrobial therapeutic drug monitoring in critically ill adult patients: a Position Paper

Purpose

This Position Paper aims to review and discuss the available data on therapeutic drug monitoring (TDM) of antibacterials, antifungals and antivirals in critically ill adult patients in the intensive care unit (ICU). This Position Paper also provides a practical guide on how TDM can be applied in routine clinical practice to improve therapeutic outcomes in critically ill adult patients.

Methods

Literature review and analysis were performed by Panel Members nominated by the endorsing organisations, European Society of Intensive Care Medicine (ESICM), Pharmacokinetic/Pharmacodynamic and Critically Ill Patient Study Groups of European Society of Clinical Microbiology and Infectious Diseases (ESCMID), International Association for Therapeutic Drug Monitoring and Clinical Toxicology (IATDMCT) and International Society of Antimicrobial Chemotherapy (ISAC). Panel members made recommendations for whether TDM should be applied clinically for different antimicrobials/classes.

Results

TDM-guided dosing has been shown to be clinically beneficial for aminoglycosides, voriconazole and ribavirin. For most common antibiotics and antifungals in the ICU, a clear therapeutic range has been established, and for these agents, routine TDM in critically ill patients appears meritorious. For the antivirals, research is needed to identify therapeutic targets and determine whether antiviral TDM is indeed meritorious in this patient population. The Panel Members recommend routine TDM to be performed for aminoglycosides, beta-lactam antibiotics, linezolid, teicoplanin, vancomycin and voriconazole in critically ill patients.

Conclusion

Although TDM should be the standard of care for most antimicrobials in every ICU, important barriers need to be addressed before routine TDM can be widely employed worldwide.

Electronic supplementary material

The online version of this article (10.1007/s00134-020-06050-1) contains supplementary material, which is available to authorized users.

Diagnostic and medical needs for therapeutic drug monitoring of antibiotics

Therapeutic drug monitoring (TDM) of antibiotics has been practiced for more than half a century, but it is still not widely applied for infected patients. It has a traditional focus on limiting toxicity of specific classes of antibiotics such as aminoglycosides and vancomycin. With more patients in critical care with higher levels of sickness severity and immunosuppression as well as an increasingly obese and ageing population, an increasing risk of suboptimal antibiotic exposure continues to escalate. As such, the value of TDM continues to expand, especially for beta-lactams which constitute the most frequently used antibiotic class. To date, the minimum inhibitory concentration (MIC) of infectious microbes rather than classification in terms of susceptible and resistant can be reported. In parallel, increasingly sophisticated TDM technology is becoming available ensuring that TDM is feasible and can deliver personalized antibiotic dosing schemes. There is an obvious need for extensive studies that will quantify the improvements in clinical outcome of individual TDM-guided dosing. We suggest that a broad diagnostic and medical investigation of the TDM arena, including market analyses and analytical technology assessment, is a current priority.

Delay in Antibiotic Administration Is Associated With Mortality Among Septic Shock Patients With Staphylococcus aureus Bacteremia

OBJECTIVES

The relationship between the timing of antibiotics and mortality among septic shock patients has not been examined among patients specifically with Staphylococcus aureus bacteremia.

DESIGN

Retrospective analysis of a Veterans Affairs S. aureus bacteremia database.

SETTING

One-hundred twenty-two hospitals in the Veterans Affairs Health System.

PATIENTS

Patients with septic shock and S. aureus bacteremia admitted directly from the emergency department to the ICU from January 1, 2003, to October 1, 2015, were evaluated.

INTERVENTIONS

Time to appropriate antibiotic administration and 30-day mortality.

MEASUREMENTS AND MAIN RESULTS

A total of 506 patients with S. aureus bacteremia and septic shock were included in the analysis. Thirty-day mortality was 78.1% for the entire cohort and was similar for those participants with methicillin-resistant S. aureus and methicillin-sensitive S. aureus bacteremia. Our multivariate analysis revealed that, as compared with those who received appropriate antibiotics within 1 hour after emergency department presentation, each additional hour that passed before appropriate antibiotics were administered produced an odds ratio of 1.11 (95% CI, 1.02-1.21) of mortality within 30 days. This odds increase equates to an average adjusted mortality increase of 1.3% (95% CI, 0.4-2.2%) for every hour that passes before antibiotics are administered.

CONCLUSIONS

The results of this study further support the importance of prompt appropriate antibiotic administration for patients with septic shock. Physicians should consider acting quickly to administer antibiotics with S. aureus coverage to any patient suspected of having septic shock.

Population pharmacokinetics of vancomycin in obesity: Finding the optimal dose for (morbidly) obese individuals

Aims

For vancomycin treatment in obese patients, there is no consensus on the optimal dose that will lead to the pharmacodynamic target (area under the curve 400–700 mg h L⁻¹). This prospective study quantifies vancomycin pharmacokinetics in morbidly obese and nonobese individuals, in order to guide vancomycin dosing in the obese.

Methods

Morbidly obese individuals (n = 20) undergoing bariatric surgery and nonobese healthy volunteers (n = 8; total body weight [TBW] 60.0–234.6 kg) received a single vancomycin dose (obese: 12.5 mg kg⁻¹, maximum 2500 mg; nonobese: 1000 mg) with plasma concentrations measured over 48 h (11–13 samples per individual). Modelling, internal validation, external validation using previously published data and simulations (n = 10.000 individuals, TBW 60–230 kg) were performed using NONMEM.

Results

In a 3‐compartment model, peripheral volume of distribution and clearance increased with TBW (both p < 0.001), which was confirmed in the external validation. A dose of 35 mg kg⁻¹ day⁻¹ (maximum 5500 mg/day) resulted in a > 90% target attainment (area under the curve > 400 mg h L⁻¹) in individuals up to 200 kg, with corresponding trough concentrations of 5.7–14.6 mg L⁻¹ (twice daily dosing). For continuous infusion, a loading dose of 1500 mg is required for steady state on day 1.

Conclusion

In this prospective, rich sampling pharmacokinetic study, vancomycin clearance was well predicted using TBW. We recommend that in obese individuals without renal impairment, vancomycin should be dosed as 35 mg kg⁻¹ day⁻¹ (maximized at 5500 mg/day). When given over 2 daily doses, trough concentrations of 5.7–14.6 mg L⁻¹ correspond to the target exposure in obese individuals.

Collaborative Antimicrobial Stewardship: Working with Information Technology

Information technology (IT) is vitally important to making antimicrobial stewardship a scalable endeavor in modern health care systems. Without IT, many antimicrobial interventions in patient care would be missed. Clinical decision support systems and smartphone apps, either stand-alone or integrated into electronic health records, can all be effective tools to help augment the work of antimicrobial stewardship programs and support the management of infectious diseases in any health care setting.

Relationship Status between Vancomycin Loading Dose and Treatment Failure in Patients with MRSA Bacteremia: It's Complicated

INTRODUCTION

A one-time vancomycin loading dose of 25-30 mg/kg is recommended in the current iteration of the vancomycin consensus guidelines in order to more rapidly achieve target serum concentrations and hasten clinical improvement. However, there are few clinical data to support this practice, and the extents of its benefits are largely unknown.

METHODS

A multicenter, retrospective, cohort study was performed to assess the impact of a vancomycin loading dose (≥ 20 mg/kg) on clinical outcomes and rates of nephrotoxicity in patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. The study matched patients in a 1:1 fashion based on age, Pitt bacteremia score, and bacteremia source. The primary outcome was composite treatment failure (30-day mortality, bacteremia duration ≥ 7 days after vancomycin initiation, persistent signs and symptoms of infection ≥ 7 days after vancomycin initiation, or switch to an alternative antimicrobial agent). Secondary outcomes included duration of bacteremia, length of stay post-bacteremia onset, and nephrotoxicity.

RESULTS

A total of 316 patients with MRSA bacteremia were included. Median first doses in the loading dose and non-loading dose groups were 23.0 mg/kg and 14.3 mg/kg, respectively (P < 0.001). No difference was found in composite failure rates between the non-loading dose and loading dose groups (40.5% vs. 36.7%; P = 0.488) or in the incidence of nephrotoxicity (12.7% vs. 16.5%; P = 0.347). While multivariable regression modeling showed receipt of a vancomycin loading dose on a mg/kg basis was not significantly associated with composite failure [aOR 0.612, 95% CI (0.368-1.019)]; post hoc analyses demonstrated that initial doses ≥ 1750 mg were independently protective against failure [aOR 0.506, 95% CI (0.284-0.902)] without increasing the risk for nephrotoxicity [aOR 0.909, 95% CI (0.432-1.911)].

CONCLUSION

These findings suggest that initial vancomycin doses above a certain threshold may decrease clinical failures without increasing toxicity and that weight-based dosing might not be the optimal strategy.

Antimicrobial de-escalation in critically ill patients: a position statement from a task force of the European Society of Intensive Care Medicine (ESICM) and European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Critically Ill Patients Study Group (ESGCIP)

BACKGROUND

Antimicrobial de-escalation (ADE) is a strategy of antimicrobial stewardship, aiming at preventing the emergence of antimicrobial resistance (AMR) by decreasing the exposure to broad-spectrum antimicrobials. There is no high-quality research on ADE and its effects on AMR. Its definition varies and there is little evidence-based guidance for clinicians to use ADE in the intensive care unit (ICU).

METHODS

A task force of 16 international experts was formed in November 2016 to provide with guidelines for clinical practice to develop questions targeted at defining ADE, its effects on the ICU population and to provide clinical guidance. Groups of 2 experts were assigned 1-2 questions each within their field of expertise to provide draft statements and rationale. A Delphi method, with 3 rounds and an agreement threshold of 70% was required to reach consensus.

RESULTS

We present a comprehensive document with 13 statements, reviewing the evidence on the definition of ADE, its effects in the ICU population and providing guidance for clinicians in subsets of clinical scenarios where ADE may be considered.

CONCLUSION

ADE remains a topic of controversy due to the complexity of clinical scenarios where it may be applied and the absence of evidence to the effects it may have on antimicrobial resistance.

Vancomycin area under the curve to minimum inhibitory concentration ratio predicting clinical outcome: a systematic review and meta-analysis with pooled sensitivity and specificity

BACKGROUND

Vancomycin is a first-line antibiotic for methicillin-resistant Staphylococcus aureus infections or other Gram-positive infections. The area under the curve (AUC) to minimum inhibitory concentration (MIC) ratio is proposed as a therapeutic drug-monitoring parameter. How well clinical efficacy is predicted by this measure has not been established.

OBJECTIVE

Determine the test performance characteristics (TPC) of AUC:MIC of vancomycin for prediction of positive outcome.

DATA SOURCES

PubMed and Ovid Medline (1946 to 2018) and EMBASE (1974 to 2018). Study Eligibility Criteria and Participants: Studies of patients treated with vancomycin for any type of infection in peer reviewed publications. All patient populations were included.

INTERVENTIONS

Vancomycin AUC:MIC or AUC was related to patient clinical outcome.

METHODS

Searches of medical databases using relevant terms were performed. Screening, study reviewing, data extracting and assessing data quality was performed independently by two reviewers. Studies were stratified by type of primary outcome for calculation of pooled sensitivity, specificity and construction of hierarchical summary receiver operating characteristic (HSROC) curves.

RESULTS

Nineteen studies including 1699 patients were meta-analysed. Pooled sensitivity and specificity were 0.77 (95% CI 0.67-0.84) and 0.62 (95% CI 0.53-0.71) respectively for the seven studies with primary outcome of mortality and 0.65 (95% CI 0.53-0.75), 0.58 (95% CI 0.48-0.67) for studies with composite or clinical cure outcome (n = 12). HSROC curves suggested considerable heterogeneity. An additional 11 studies were described but could not be included for meta-analysis because data were not available. The majority of these studies (9/11) failed to demonstrate a relationship between AUC:MIC and positive clinical outcome.

CONCLUSIONS

Vancomycin AUC:MIC performance was modest and inconsistent. Analysis was limited by studies without sufficient data; therefore, meta-analytic results may overestimate TPC values. Given this, as well as the lack of standardization of methods, widespread adoption of AUC:MIC as the preferred vancomycin monitoring parameter may be premature.

Target-Controlled Continuous Infusion for Antibiotic Dosing: Proof-of-Principle in an In-silico Vancomycin Trial in Intensive Care Unit Patients

OBJECTIVES

In this in-silico study, we investigate the clinical utility of target-controlled infusion for antibiotic dosing in an intensive care unit setting using vancomycin as a model compound. We compared target-controlled infusion and adaptive target-controlled infusion, which combines target-controlled infusion with data from therapeutic drug monitoring, with conventional (therapeutic drug monitoring-based) vancomycin dosing strategies.

METHODS

A clinical trial simulation was conducted. This simulation was based on a comprehensive database of clinical records of intensive care unit patients and a systematic review of currently available population-pharmacokinetic models for vancomycin in intensive care unit patients. Dosing strategies were compared in terms of the probability of achieving efficacious concentrations as well as the potential for inducing toxicity.

RESULTS

Adaptive target-controlled infusion outperforms rule-based dosing guidelines for vancomycin. In the first 48 h of treatment, the probability of target attainment is significantly higher for adaptive target-controlled infusion than for the second-best method (Cristallini). Probability of target attainments of 54 and 72% and 47 and 59% for both methods after 24 and 48 h, respectively. Compared to the Cristallini method, which is characterized by a probability of attaining concentrations above 30 mg.L^-1 > 65% in the first few hours of treatment, adaptive target-controlled infusion shows negligible time at risk and a probability of attaining concentrations above 30 mg.L^-1 not exceeding 25%. Finally, in contrast to the other methods, the performance of target-controlled infusion is consistent across subgroups within the population.

CONCLUSIONS

Our study shows that adaptive target-controlled infusion has the potential to become a practical tool for patient-tailored antibiotic dosing in the intensive care unit.

Vancomycin population pharmacokinetics for adult patients with sepsis or septic shock: are current dosing regimens sufficient?

PURPOSE

Vancomycin is commonly used for the management of severe infections; however, vancomycin dosing may be challenging in critically ill patients. This observational study aims to describe the population pharmacokinetics of vancomycin in adult patients with sepsis or septic shock.

METHODS

A single-centre retrospective review of adult patients with sepsis or septic shock receiving vancomycin with therapeutic drug monitoring was undertaken. Blood samples taken 1 h after the vancomycin infusion cessation and 30 min prior to the next dose were assayed using the Vitros Crea Slide method. Vancomycin concentrations determined on different days were included. A pharmacokinetic model was developed using Pmetrics for R. Monte Carlo dosing simulations were performed using the final model.

RESULTS

Vancomycin concentrations were available for 27 adult patients admitted to the intensive care unit with sepsis or septic shock. A one-compartment pharmacokinetic model with inter-occasion variability of clearance and volume of distribution before and after 72 h adequately described the data. Creatinine clearance normalized to body surface area was included as a covariate on vancomycin clearance. The clearance and volume of distribution within 72 h of admission were 7.29 L/h and 54.20 L, respectively. Monte Carlo simulations suggested that for patients with a creatinine clearance of ≥ 80 mL/min/1.73 m², vancomycin doses of ≥ 2 g every 8 h are required to consistently achieve key therapeutic targets.

CONCLUSIONS

Vancomycin doses ≥ 2 g every 8 h in adult patients with sepsis or septic shock with a creatinine clearance ≥ 80 mL/min/1.73 m² are likely needed to achieve an optimal therapeutic exposure.

Antibiotic use in critical illness

OBJECTIVE

To provide a review on the current use of antimicrobials with a discussion on the pharmacokinetic and pharmacodynamic profiles of antimicrobials in critically ill patients, the challenges of drug resistance, the use of diagnostic testing to direct therapy, and the selection of the most likely efficacious antimicrobial protocol.

ETIOLOGY

Patients in the intensive care unit often possess profound pathophysiologic changes that can complicate antimicrobial therapy. Although many antimicrobials have known pharmacodynamic profiles, critical illness can cause wide variations in their pharmacokinetics. The two principal factors affecting pharmacokinetics are volume of distribution and drug clearance. Understanding the interplay between critical illness, drug pharmacokinetics, and antimicrobial characteristics (ie, time-dependent vs concentration-dependent) may improve antimicrobial efficacy and patient outcome.

DIAGNOSIS

Utilizing bacterial culture and susceptibility can aid in identifying drug resistant infections, selecting the most appropriate antimicrobials, and hindering the future development of drug resistance.

THERAPY

Having a basic knowledge of antimicrobial function and how to use diagnostics to direct therapeutic treatment is paramount in managing this patient population. Diagnostic testing is not always available at the time of initiation of antimicrobial therapy, so empiric selections are often necessary. These empiric choices should be made based on the location of the infection and the most likely infecting bacteria.

PROGNOSIS

Studies have demonstrated the importance of moving away from a "one dose fits all" approach to antimicrobial therapy. Instead there has been a move toward an individualized approach that takes into consideration the pharmacokinetic and pharmacodynamic variabilities that can occur in critically ill patients.

Overcoming barriers to optimal drug dosing during ECMO in critically ill adult patients

INTRODUCTION

One major challenge to achieving optimal patient outcome in extracorporeal membrane oxygenation (ECMO) is the development of effective dosing strategies in this critically ill patient population. Suboptimal drug dosing impacts on patient outcome as patients on ECMO often require reversal of the underlying pathology with effective pharmacotherapy in order to be liberated of the life-support device. Areas covered: This article provides a concise review of the effective use of antibiotics, analgesics, and sedative by characterizing the specific changes in PK secondary to the introduction of the ECMO support. We also discuss the barriers to achieving optimal pharmacotherapy in patients on ECMO and also the current and potential research that can be undertaken to address these clinical challenges. Expert opinion: Decreased bioavailability due to sequestration of drugs in the ECMO circuit and ECMO induced PK alterations are both significant barriers to optimal drug dosing. Evidence-based drug choices may minimize sequestration in the circuit and would enable safety and efficacy to be maintained. More work to characterize ECMO related pharmacodynamic alterations such as effects of ECMO on hepatic cytochrome system are still needed. Novel techniques to increase target site concentrations should also be explored.

Relationship Between Initial Vancomycin Trough Levels and Early-Onset Vancomycin-Associated Nephrotoxicity in Critically Ill Patients

BACKGROUND

Appropriate initial dosing of vancomycin (VCM) is important in improving survival and in preventing nephrotoxicity in critically ill patients, but the potential relationship between initial VCM trough levels and early-onset nephrotoxicity remains unclear. We examined the relationship between initial VCM trough levels and early-onset VCM-associated nephrotoxicity.

METHODS

We performed a retrospective study of patients who had therapeutic drug monitoring of VCM with initial trough levels within 4 days after the beginning of VCM administration. We excluded patients who received renal replacement therapy from 2 days before to 7 days after the beginning of VCM administration, were younger than 18 years, or had renal dysfunction before the beginning of VCM administration. Early-onset VCM-associated nephrotoxicity was defined as an increase in serum creatinine level of ≥0.5 mg/dL (44.2 μmol/L) or 50% above baseline for 2 or more consecutive days within 7 days after the beginning of VCM administration.

RESULTS

Among 109 enrolled patients, 13 patients had early-onset VCM-associated nephrotoxicity. Its incidence rate was 31.3% in patients with initial trough levels of ≥20g/mL, which was significantly higher than 6.3% in patients with initial trough levels of <10 mg/L. Multiple logistic regression analysis demonstrated that early-onset VCM-associated nephrotoxicity was associated with initial trough levels of ≥20 mg/L (odds ratio, 5.0; 95% confidence interval, 1.3-19.1) and with vasopressor use (odds ratio, 5.0; 95% confidence interval, 1.3-19.1). Kaplan-Meier analysis showed that the probability of nonnephrotoxicity for patients with initial VCM trough levels of ≥20 mg/L was lower compared with patients with trough levels of <15 mg/L.

CONCLUSIONS

Initial trough levels of ≥20 mg/L but not ≥15 mg/L were associated with early-onset VCM-associated nephrotoxicity in critically ill patients. Future prospective studies are needed to examine outcomes in critically ill patients achieving initial VCM trough levels of 15-20 mg/L.

Augmented Renal Clearance in Critically Ill Patients: A Systematic Review

BACKGROUND

Traditionally, renal function in critically ill patients has been assessed to identify renal dysfunction, and dose adjustment is generally accepted in such a context. Nevertheless, augmented renal clearance (ARC) is a less well-studied phenomenon that could lead to faster elimination of drugs, resulting in subtherapeutic concentrations and poorer clinical outcomes when standard dosage guidelines are followed.

OBJECTIVE

The aim of this systematic review was to gather and summarise all the available evidence on ARC in critically ill patients, including its definition, underlying mechanisms, epidemiology, diagnosis and impact on both drug pharmacokinetics and clinical outcomes.

METHOD

A systematic review was conducted to include all the original studies that provided information on ARC in critically ill patients, and is reported following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Augmented renal clearance, defined as a creatinine clearance (CrCl) > 130 mL/min/1.73 m2, preferably measured in urine, is present in 20-65% of critically ill patients. Younger age, polytrauma and lower severity illness have been identified as risk factors. An influence of ARC on antimicrobial pharmacokinetics has been observed, with ARC consistently being associated with subtherapeutic antibiotic plasma concentrations.

CONCLUSION

ARC is a prevalent condition in critically ill patients, especially in young people, with urinary CrCl being the best diagnostic method because mathematical estimates tend to underestimate CrCl. ARC increases renal drug elimination and has a clear influence on certain antimicrobial plasma levels, but is yet to define its impact on clinical outcomes and on pharmacokinetics of other types of drugs. Research on the need to stage ARC and establish specific dosing guidelines is warranted.

Individualized Pharmacokinetic Dosing of Vancomycin Reduces Time to Therapeutic Trough Concentrations in Critically Ill Patients

Dosing vancomycin in critically ill patients often results in subtherapeutic and supratherapeutic trough concentrations. In this retrospective study, we compared the time to goal trough attainment and incidence of acute kidney injury in intensive care unit (ICU) patients whose vancomycin was dosed by a pharmacy pharmacokinetic (PK) dosing and monitoring service to the standard of care. Three-hundred fifty adult ICU patients at a Level 1 trauma, teaching hospital who received vancomycin for >24 hours from February 1, 2016, to November 30, 2016, were screened. Patients were included in the PK group if consecutive serum concentrations were used to calculate individualized PK and determine a dosing regimen. Patients who were dosed using troughs only were then matched 1-to-1 to the PK group by date of vancomycin initiation and included in the traditional group. Fifty patients were included in each group. Baseline characteristics were similar, except the PK group had more patients under the care of the neuromedical ICU service (42% vs 18%; P = .02) and fewer patients with a corrected creatinine clearance <30 mL/min/1.73 m² (22% vs 46%; P = .02). Attainment of goal trough concentrations for the PK and traditional groups were 84.4% and 29.4% by 48 hours (P = .0001), 88.4% and 60.7% by 72 hours (P = .009), and 92.9% and 77.8% by 96 hours (P = .1), respectively. Incidence of acute kidney injury between the PK and traditional groups was not statistically significant (8.3% vs 14%; P = .5). Utilization of individualized pharmacokinetic dosing of vancomycin in critically ill patients resulted in faster goal trough attainment without an increase in nephrotoxicity.

New paradigm for rapid achievement of appropriate therapy in special populations: coupling antibiotic dose optimization rapid microbiological methods

INTRODUCTION

Some special patient populations (e.g. critically ill, burns, hematological malignancy, post-major surgery, post-major trauma) have characteristics that lead to higher rates of failure and mortality associated with infection. Choice of effective antibiotics and optimized doses are challenging in these patients that are commonly infected by multidrug-resistant pathogens. Areas covered: A review of the importance of diagnosis and the place of newer microbiological methods (e.g. whole-genome sequencing) to ensure rapid transition from empiric to directed antibiotic therapy is provided. The effects of pathophysiological changes on antibiotic pharmacokinetics are also provided. Expert opinion: Product information dosing regimens do not address the pharmacokinetic alterations that can occur in special patient populations and increase the likelihood of therapeutic failure and the emergence of bacterial resistance. Altered dosing approaches, supplemented with the use of dosing software and therapeutic drug monitoring, may be needed to ensure optimal antibiotic exposure and better therapeutic outcomes in these patients with severe infection. Dose optimization needs to be coupled with advanced microbiological techniques that enable rapid microbiological identification and characterization of resistance mechanism to ensure that maximally effective directed therapy can be chosen.

Optimisation of antimicrobial dosing based on pharmacokinetic and pharmacodynamic principles

While suboptimal dosing of antimicrobials has been attributed to poorer clinical outcomes, clinical cure and mortality advantages have been demonstrated when target pharmacokinetic (PK) and pharmacodynamic (PD) indices for various classes of antimicrobials were achieved to maximise antibiotic activity. Dosing optimisation requires a good knowledge of PK/PD principles. This review serves to provide a foundation in PK/PD principles for the commonly prescribed antibiotics (β-lactams, vancomycin, fluoroquinolones and aminoglycosides), as well as dosing considerations in special populations (critically ill and obese patients). PK principles determine whether an appropriate dose of antimicrobial reaches the intended pathogen(s). It involves the fundamental processes of absorption, distribution, metabolism and elimination, and is affected by the antimicrobial's physicochemical properties. Antimicrobial pharmacodynamics define the relationship between the drug concentration and its observed effect on the pathogen. The major indicator of the effect of the antibiotics is the minimum inhibitory concentration. The quantitative relationship between a PK and microbiological parameter is known as a PK/PD index, which describes the relationship between dose administered and the rate and extent of bacterial killing. Improvements in clinical outcomes have been observed when antimicrobial agents are dosed optimally to achieve their respective PK/PD targets. With the rising rates of antimicrobial resistance and a limited drug development pipeline, PK/PD concepts can foster more rational and individualised dosing regimens, improving outcomes while simultaneously limiting the toxicity of antimicrobials.

Achievement of Therapeutic Vancomycin Exposure With Continuous Infusion in Critically Ill Children

OBJECTIVE

Describe and assess a continuous infusion dosing scheme of vancomycin therapy in critically ill children.

DESIGN

Retrospective single-center study, January to June 2015.

SETTING

PICU located within a French tertiary academic pediatric hospital.

PATIENTS

All children admitted in the PICU from January 2015 to June 2015, receiving continuous infusion of vancomycin therapy.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Clinical and biological data, vancomycin dosing information, and plasma concentrations were recorded. Using a previously published population pharmacokinetics model, pharmacokinetic parameters were derived for each patient and vancomycin concentrations described after the loading dose. Areas under the curve were estimated for each patient, and an initial covariate-adjusted dose was calculated for every patient. A total of 87 vancomycin concentrations were analyzed from 28 patients between 1 month and 17 years old. The median (range) loading dose was 14.8 (12-16) mg/kg followed by a continuous infusion of vancomycin of 44 (35-61) mg/kg/d. On their first sample, 12 patients (43%) had a concentration between 15 and 30 mg/L. On day 1, the median (range) estimated area under the curve was 349 (201-1,001) mg/L × hr, and seven patients (25%) had an area under the curve greater than 400 mg/L × hr. Using the pharmacokinetics model, the median (range) calculated initial daily dose, taking into account age, bodyweight, and serum creatinine concentration, was 53 (36-69) mg/kg/d resulting in a simulated day 1 area under the curve of 409 (341-593) mg/L × h with a theoretical pharmacokinetic target attainment of 57%.

CONCLUSIONS

The current continuous infusion of vancomycin dosing scheme used in our population was inappropriate and led to underexposure. Using pharmacokinetic approaches such as covariate-adjusted initial dosing and Bayesian estimation of exposure should prove useful for achieving the pharmacokinetic target.