Vancomycin continuous infusion in neonates: dosing optimisation and therapeutic drug monitoring

Optimization of Vancomycin Initial Dosing Regimen in Neonates Using an Externally Evaluated Population Pharmacokinetic Model

BACKGROUND

Vancomycin therapeutic monitoring guidelines were revised in March 2020, and a population pharmacokinetics-guided Bayesian approach to estimate the 24-hour area under the concentration-time curve to the minimum inhibitory concentration ratio has since been recommended instead of trough concentrations. To comply with these latest guidelines, we evaluated published population pharmacokinetic models of vancomycin using an external dataset of neonatal patients and selected the most predictive model to develop a new initial dosing regimen.

METHODS

The models were identified from the literature and tested using a retrospective dataset of Canadian neonates. Their predictive performance was assessed using prediction- and simulation-based diagnostics. Monte Carlo simulations were performed to develop the initial dosing regimen with the highest probability of therapeutic target attainment.

RESULTS

A total of 144 vancomycin concentrations were derived from 63 neonates in the external population. Five of the 28 models retained for evaluation were found predictive with a bias of 15% and an imprecision of 30%. Overall, the Grimsley and Thomson model performed best, with a bias of -0.8% and an imprecision of 20.9%; therefore, it was applied in the simulations. A novel initial dosing regimen of 15 mg/kg, followed by 11 mg/kg every 8 hours should favor therapeutic target attainment.

CONCLUSIONS

A predictive population pharmacokinetic model of vancomycin was identified after an external evaluation and used to recommend a novel initial dosing regimen. The implementation of these model-based tools may guide physicians in selecting the most appropriate initial vancomycin dose, leading to improved clinical outcomes.

Subgroup identification-based model selection to improve the predictive performance of individualized dosing

Currently, model-informed precision dosing uses one population pharmacokinetic model that best fits the target population. We aimed to develop a subgroup identification-based model selection approach to improve the predictive performance of individualized dosing, using vancomycin in neonates/infants as a test case. Data from neonates/infants with at least one vancomycin concentration was randomly divided into training and test dataset. Population predictions from published vancomycin population pharmacokinetic models were calculated. The single best-performing model based on various performance metrics, including median absolute percentage error (APE) and percentage of predictions within 20% (P20) or 60% (P60) of measurement, were determined. Clustering based on median APEs or clinical and demographic characteristics and model selection by genetic algorithm was used to group neonates/infants according to their best-performing model. Subsequently, classification trees to predict the best-performing model using clinical and demographic characteristics were developed. A total of 208 vancomycin treatment episodes in training and 88 in test dataset was included. Of 30 identified models from the literature, the single best-performing model for training dataset had P20 26.2-42.6% in test dataset. The best-performing clustering approach based on median APEs or clinical and demographic characteristics and model selection by genetic algorithm had P20 44.1-45.5% in test dataset, whereas P60 was comparable. Our proof-of-concept study shows that the prediction of the best-performing model for each patient according to the proposed model selection approaches has the potential to improve the predictive performance of model-informed precision dosing compared with the single best-performing model approach.

Prospective validation of a model-informed precision dosing tool for vancomycin treatment in neonates

We recruited 48 neonates (50 vancomycin treatment episodes) in a prospective study to validate a model-informed precision dosing (MIPD) software. The initial vancomycin dose was based on a population pharmacokinetic model and adjusted every 36-48 h. Compared with a historical control group of 53 neonates (65 episodes), the achievement of a target trough concentration of 10-15 mg/L improved from 37% in the study to 62% in the MIPD group (P = 0.01), with no difference in side effects.

Bayesian Vancomycin Model Selection for Therapeutic Drug Monitoring in Neonates

BACKGROUND AND OBJECTIVE

Pharmacokinetic models can inform drug dosing of vancomycin in neonates to optimize therapy. However, the model selected needs to describe the intended population to provide appropriate dose recommendations. Our study aims to identify the population pharmacokinetic (PopPK) model(s) with the best performance to predict vancomycin exposure in neonates in our hospital.

METHODS

Relevant published PopPK models for vancomycin in neonates were selected based on demographics and vancomycin dosing strategy. The predictive performance of the models was evaluated in Tucuxi using a local cohort of 69 neonates. Mean absolute error (MAE), relative bias (rBias) and relative root mean square error (rRMSE) were used to quantify the accuracy and precision of the predictive performance of each model for three different approaches: a priori, a posteriori, and Bayesian forecasting for the next course of therapy based on the previous course predictions. A PopPK model was considered clinically acceptable if rBias was between ± 20 and 95% confidence intervals included zero.

RESULTS

A total of 25 PopPK models were identified and nine were considered suitable for further evaluation. The model of De Cock et al. 2014 was the only clinically acceptable model based on a priori [MAE 0.35 mg/L, rBias 0.8 % (95% confidence interval (CI) - 7.5, 9.1%), and rRMSE 8.9%], a posteriori [MAE 0.037 mg/L, rBias - 0.23% (95% CI - 1.3, 0.88%), and rRMSE 6.02%] and Bayesian forecasting for the next courses [MAE 0.89 mg/L, rBias 5.45% (95% CI - 8.2, 19.1%), and rRMSE 38.3%) approaches.

CONCLUSIONS

The De Cock model was selected based on a comprehensive approach of model selection to individualize vancomycin dosing in our neonates.

One-Step Detection of Vancomycin in Whole Blood Using the Lateral Flow Immunoassay

Vancomycin (VAN) is an effective antibiotic against Gram-positive bacteria and the first-line therapy to prevent and treat methicillin-resistant Staphylococcus aureus (MRSA) and severe infections. However, low concentrations of VAN can result in resistant strains. High doses of VAN can cause nephrotoxicity and ototoxicity; thus, VAN is a representative drug for which drug monitoring is recommended. Several methods have been proposed to detect VAN. Among them, lateral flow immunoassays (LFIAs) have advantages, such as simple and user-friendly operation, low sample volume requirement, and cost effectiveness. In this study, we developed an LFIA capable of rapid on-site detection such that the VAN concentration in plasma could be monitored within 20 min by a one-step detection process using whole blood without plasma separation. VAN can be detected in whole blood over a wide range of concentrations (20-10,000 ng/mL), and the LFIA reported here has a detection limit of 18 ng/mL. The applicability of the developed LFIA compared to the results of measuring VAN with a commercial enzyme-linked immunosorbent assay kit showed a satisfactory correlation (Spearman's rho, ρ = 0.891). Therefore, the developed LFIA enables rapid and wide-range VAN detection in whole blood and can aid in drug monitoring to evaluate patients' responses to treatment.

Using population pharmacokinetics to optimize initial vancomycin dosing guidelines for neonates to treat sepsis caused by coagulase-negative staphylococcus

INTRODUCTION

Vancomycin dosing tailored for newborns is challenging due to the significant influence of maturation and organ function on pharmacokinetics. Population pharmacokinetic (popPK) models can be used to improve target attainment in neonates.

OBJECTIVES

The primary objective was to derive and evaluate a popPK model of intravenous vancomycin for neonates. Second, the predictive performance of this popPK model was compared with published popPK models.

METHODS

This is a retrospective cohort study of neonates admitted to the neonatal intensive care unit receiving intravenous vancomycin. A popPK model was derived with 70% of the dataset using a nonlinear mixed effects modeling method. The predictive performance of the current popPK model was validated and compared with 22 published popPK models using the remaining 30% of the dataset. Monte Carlo simulations (MCS) were performed to derive optimal dosing regimens to treat neonatal sepsis caused by coagulase-negative staphylococci (CoNS).

RESULTS

Among 655 vancomycin courses from 448 neonates, 78% of vancomycin trough concentrations were outside target range (10-15 mg/L) for central nervous system infections and 43% were outside target range (5-12 mg/L) for other infections using the institution's vancomycin dosing. A one-compartment model best described the observed data with a mean clearance of 0.11 ± 0.03 L/kg/h and volume of distribution (V) of 1.02 ± 0.08 L/kg. Body weight (WT), postmenstrual age (PMA), and serum creatinine (SCr) were significant covariates associated with clearance (p < 0.001) and body WT was a significant covariate associated with V (p = 0.009). Our study's popPK model has similar or better accuracy and precision than other published models. MCS-derived vancomycin doses from the validated model achieved >90% target attainment for a steady state through target range of 10-15 mg/L in the majority of PMA and SCr categories (78%) to treat CoNS sepsis.

CONCLUSION

A vancomycin dosing guideline derived from a validated popPK model in neonates with CoNS sepsis is recommended to improve target attainment.

Individualized vancomycin dosing in infants: prospective evaluation of an online dose calculator

BACKGROUND

Empiric vancomycin dosing regimens fail to achieve recommended target trough concentrations of 10-20 mg/L in the majority of infants. This study assessed the performance of a model-based dosing calculator (Vanc App) in achieving target vancomycin concentrations at first steady-state level.

METHODS

This was a multicenter prospective study in four tertiary pediatric hospitals over an 18-month period. Infants aged 0-90 days with suspected Gram-positive sepsis requiring empiric vancomycin treatment were included if they did not meet any of the exclusion criteria: post-menstrual age (PMA) <25 weeks, weight <500 g, glycopeptide allergy, receiving extracorporeal membrane oxygenation, vancomycin use within the previous 72 h, and renal impairment. The Vanc App used a published population pharmacokinetic model to generate a dose based on the infant's PMA, weight, creatinine, and target vancomycin concentration.

RESULTS

A total of 40 infants were included; 40% were female, median (range) weight was 2505 (700-4460) g and median (range) PMA was 37.4 (25.7-49.0) weeks. The median (range) vancomycin dose was 45 (24-79) mg/kg/day. All infants had trough vancomycin concentrations measured at steady-state (24-<48 hours) and 30 (75%) infants achieved target concentrations. Five infants had supratherapeutic (median 25, range 21-38 mg/L) and five had subtherapeutic (median 6, range <5-9 mg/L) concentrations. An area under the concentration-time curve (AUC_0-24) of 400-650 mg/L.h was achieved in 33 (83%) infants. There were no infusion-related reactions or nephrotoxicity.

CONCLUSION

Individualized intermittent vancomycin dosing using a model-based online calculator resulted in 75% and 83% of infants achieving target trough and AUC_0-24, respectively, at first steady-state level. There were no vancomycin-related nephrotoxicity or infusion-related reactions.

Evaluation of vancomycin individualized model-based dosing approach in neonates

BACKGROUND

Vancomycin is commonly used to treat methicillin-resistant staphylococcal infections in neonates. Consensus on its ideal dosing in neonates has not been achieved. Model-based dosing recently has evolved as an important tool to optimize vancomycin initial dosing. The aim of this is to evaluate a population pharmacokinetic model-based approach in achieving the vancomycin therapeutic target of an AUC_0-24 400 as recommended by the recent IDSA treatment guidelines. This model was implemented as a simple Excel calculator to individualize and optimize vancomycin initial dosing in neonates.

METHODS

An Excel calculator was developed using a previously published population pharmacokinetic model in neonates. It was evaluated using retrospectively retrieved data. For each patient, the initial empiric dose was calculated using the proposed Excel model and the most widely used neonatal dosing references. The probability of achieving the target AUC_0-24 of >400 mg h/L using the model-based method was calculated and compared with that of the empiric doses using other references.

RESULTS

This analysis included 225 neonates. The probability of achieving the target AUC_0-24 >400 was 89% using our model-based approach compared with 11%-59% using tertiary neonatal dosing references (p < 0.01 for all comparisons).

CONCLUSION

These innovative personalized dosing calculators are promising to improve vancomycin initial dosing in neonates and are easily applicable in routine practices.

Meropenem for children with severe pneumonia: Protocol for a randomized controlled trial

Background: Pneumonia, caused by infection or other factors, seriously endangers the health of children. Meropenem is an effective broad-spectrum antibiotic using in the treatment of infectious diseases. In the therapy of pneumonia, meropenem is mostly employed for the treatment of moderate to severe pneumonia. Previously, we established a population pharmacokinetics (PPK) model for meropenem in pediatric severe infection and simulated the control rate of the time during which the free plasma concentration of meropenem exceeds the minimum inhibitory concentration (MIC) is 70% of the dosing interval (70% fT &gt; MIC). Therefore, we plan to conduct a multicenter randomized controlled trial (RCT) to compare the efficacy and safety between conventional regimen and model regimen for meropenem in pediatric severe pneumonia.

Methods: One hundred patients (aged 3 months to 15 years) will be recruited in this RCT. They will be assigned randomly (at a 1:1 ratio) to a conventional treatment group (20 mg/kg, q8h, with 0.5–1 h infusion) and a model treatment group (20 mg/kg, q8 h, with 4 h infusion). The primary outcome will be 70% fT &gt; MIC. Secondary outcomes will be the prevalence of meropenem therapy failure, duration of antibiotic therapy, changes in levels of inflammatory indicators, changes in imaging examination results, and prevalence of adverse events. Ethical approval of our clinical trial has been granted by the ethics committee of Beijing Children’s Hospital ([2022]-E-133-Y). This trial has been registered in the Chinese Clinical Trial Registry (ChiCTR2200061207).

Discussion: Based on our previous PPK data, we have designed this RCT. It is hoped that it will promote rational use of antibacterial drugs in children suffering from severe pneumonia.

Clinical Trial Registration: http://www.chictr.org.cn identifier, ChiCTR2200061207.

Use of Antibiotics in Preterm Newborns

Due to complex maturational and physiological changes that characterize neonates and affect their response to pharmacological treatments, neonatal pharmacology is different from children and adults and deserves particular attention. Although preterms are usually considered part of the neonatal population, they have physiological and pharmacological hallmarks different from full-terms and, therefore, need specific considerations. Antibiotics are widely used among preterms. In fact, during their stay in neonatal intensive care units (NICUs), invasive procedures, including central catheters for parental nutrition and ventilators for respiratory support, are often sources of microbes and require antimicrobial treatments. Unfortunately, the majority of drugs administered to neonates are off-label due to the lack of clinical studies conducted on this special population. In fact, physiological and ethical concerns represent a huge limit in performing pharmacokinetic (PK) studies on these subjects, since they limit the number and volume of blood sampling. Therapeutic drug monitoring (TDM) is a useful tool that allows dose adjustments aiming to fit plasma concentrations within the therapeutic range and to reach specific drug target attainment. In this review of the last ten years’ literature, we performed Pubmed research aiming to summarize the PK aspects for the most used antibiotics in preterms.

Optimization of Vancomycin Initial Dose in Term and Preterm Neonates by Machine Learning

INTRODUCTION

Vancomycin is one of the antibiotics most used in neonates. Continuous infusion has many advantages over intermittent infusions, but no consensus has been achieved regarding the optimal initial dose. The objectives of this study were: to develop a Machine learning (ML) algorithm based on pharmacokinetic profiles obtained by Monte Carlo simulations using a population pharmacokinetic model (POPPK) from the literature, in order to derive the best vancomycin initial dose in preterm and term neonates, and to compare ML performances with those of an literature equation (LE) derived from a POPPK previously published.

MATERIALS AND METHODS

The parameters of a previously published POPPK model of vancomycin in children and neonates were used in the mrgsolve R package to simulate 1900 PK profiles. ML algorithms were developed from these simulations using Xgboost, GLMNET and MARS in parallel, benchmarked and used to calculate the ML first dose. Performances were evaluated in a second simulation set and in an external set of 82 real patients and compared to those of a LE.

RESULTS

The Xgboost algorithm yielded numerically best performances and target attainment rates: 46.9% in the second simulation set of 400-600 AUC/MIC ratio vs. 41.4% for the LE model (p = 0.0018); and 35.3% vs. 28% in real patients (p = 0.401), respectively). The Xgboost model resulted in less AUC/MIC > 600, thus decreasing the risk of nephrotoxicity.

CONCLUSION

The Xgboost algorithm developed to estimate the initial dose of vancomycin in term or preterm infants has better performances than a previous validated LE and should be evaluated prospectively.

Role of fluid status markers as risk factors for suboptimal vancomycin concentration during continuous infusion in neonates: an observational study

Vancomycin is widely used in neonatal sepsis but proportion of newborn reaching recommended concentration is variable. Fluid status impact on vancomycin level remains understudied. We aimed to study fluid factors impacting vancomycin concentration at 24 h of treatment. We performed a prospective and retrospective observational monocentric study of NICU patients requiring a vancomycin treatment. We used a continuous infusion protocol, with age-appropriate loading and maintenance doses. Vancomycin target serum concentration after 24 h (C_24h) was above 20 mg/L. Demographic, infections, and organ failure variables were analyzed as potential predictors of C_24h. Over the study period, 70 infective episodes in 52 patients were included. At treatment initiation, the median post-natal age was 12.5 days (IQR 7-23), post menstrual age 30 weeks (IQR 28-35), and median weight 1140 g (IQR 835-1722). Germs isolated were mainly gram-positive with 73.5% being coagulase-negative Staphylococci. Median C_24h was 18.7 mg/L (IQR 15.4-22.4). Overall, 41 (58.6%) treatments had a C_24h < 20 mg/L. After multivariate analysis, higher creatinine level (OR 1.03 (95% CI 1.002-1.06)) was associated with C_24h ≥ 20 mg/L; weight gain the day before infection (OR 0.21 (95% CI 0.05-0.79)) and positive biomarkers of inflammation (OR 0.22 (0.05-0.94)) were associated with C_24h < 20 mg/L.

CONCLUSION

Vancomycin C_24h was underdosed in 60% of patients and factors linked to changes in vancomycin pharmacokinetic such as volume of distribution and clearance, linked to creatinine level, inflammation, or weight gain, were identified.

WHAT IS KNOWN

• Adjustment of vancomycin regimen remains difficult due to inter- and intra-individual variability of vancomycin pharmacokinetics. • Impact of fluid status on vancomycin concentration in critically ill neonates is incompletely studied.

WHAT IS NEW

• Proportion of patients with adequate vancomycin concentration using a target adapted to nosocomial gram-positive bacteria MIC is low. • We confirmed the role of creatinine level and report two new factors associated with low vancomycin concentration: presence of systemic inflammation and weight gain.

Predictive Performance of Pharmacokinetic Model-Based Virtual Trials of Vancomycin in Neonates: Mathematics Matches Clinical Observation

BACKGROUND AND OBJECTIVE

Vancomycin is frequently used to treat Gram-positive bacterial infections in neonates. However, there is still no consensus on the optimal initial dosing regimen. This study aimed to assess the performance of pharmacokinetic model-based virtual trials to predict the dose-exposure relationship of vancomycin in neonates.

METHODS

The PubMed database was searched for clinical trials of vancomycin in neonates that reported the percentage of target attainment. Monte Carlo simulations were performed using nonlinear mixed-effect modeling to predict the dose-exposure relationship, and the differences in outcomes between virtual trials and real-world data in clinical studies were calculated.

RESULTS

A total of 11 studies with 14 dosing groups were identified from the literature to evaluate dose-exposure relationships. For the ten dosing groups where the surrogate marker for exposure was the trough concentration, the mean ± standard deviation (SD) for the target attainment between original studies and virtual trials was 3.0 ± 7.3%. Deviations between - 10 and 10% accounted for 80% of the included dosing groups. For the other four dosing groups where the surrogate marker for exposure was concentration during continuous infusion, all deviations were between - 10 and 10%, and the mean ± SD value was 2.9 ± 4.5%.

CONCLUSION

The pharmacokinetic model-based virtual trials of vancomycin exhibited good predictive performance for dose-exposure relationships in neonates. These results might be used to assist the optimization of dosing regimens in neonatal practice, avoiding the need for trial and error.

Evaluation of a Meropenem and Piperacillin Monitoring Program in Intensive Care Unit Patients Calls for the Regular Assessment of Empirical Targets and Easy-to-Use Dosing Decision Tools

The drug concentrations targeted in meropenem and piperacillin/tazobactam therapy also depend on the susceptibility of the pathogen. Yet, the pathogen is often unknown, and antibiotic therapy is guided by empirical targets. To reliably achieve the targeted concentrations, dosing needs to be adjusted for renal function. We aimed to evaluate a meropenem and piperacillin/tazobactam monitoring program in intensive care unit (ICU) patients by assessing (i) the adequacy of locally selected empirical targets, (ii) if dosing is adequately adjusted for renal function and individual target, and (iii) if dosing is adjusted in target attainment (TA) failure. In a prospective, observational clinical trial of drug concentrations, relevant patient characteristics and microbiological data (pathogen, minimum inhibitory concentration (MIC)) for patients receiving meropenem or piperacillin/tazobactam treatment were collected. If the MIC value was available, a target range of 1–5 × MIC was selected for minimum drug concentrations of both drugs. If the MIC value was not available, 8–40 mg/L and 16–80 mg/L were selected as empirical target ranges for meropenem and piperacillin, respectively. A total of 356 meropenem and 216 piperacillin samples were collected from 108 and 96 ICU patients, respectively. The vast majority of observed MIC values was lower than the empirical target (meropenem: 90.0%, piperacillin: 93.9%), suggesting empirical target value reductions. TA was found to be low (meropenem: 35.7%, piperacillin 50.5%) with the lowest TA for severely impaired renal function (meropenem: 13.9%, piperacillin: 29.2%), and observed drug concentrations did not significantly differ between patients with different targets, indicating dosing was not adequately adjusted for renal function or target. Dosing adjustments were rare for both drugs (meropenem: 6.13%, piperacillin: 4.78%) and for meropenem irrespective of TA, revealing that concentration monitoring alone was insufficient to guide dosing adjustment. Empirical targets should regularly be assessed and adjusted based on local susceptibility data. To improve TA, scientific knowledge should be translated into easy-to-use dosing strategies guiding antibiotic dosing.

Implementation of a Vancomycin Dose-Optimization Protocol in Neonates: Impact on Vancomycin Exposure, Biological Parameters, and Clinical Outcomes

Vancomycin dosing used in neonates results frequently in insufficient concentrations. A vancomycin dose-optimization protocol consisting of an individualization of loading and maintenance doses (administered during continuous infusion) through a previously validated pharmacokinetic model was implemented in our center. This monocenter retrospective study aimed to compare vancomycin average concentration (Cavg) in the therapeutic range (15 to 25 mg/L) and biological and clinical parameters before and after implementation of this protocol. A total of 60 and 59 courses of vancomycin treatment in 45 and 49 patients were analyzed in groups before and after implementation, respectively. Initial vancomycin Cavg were more frequently in the therapeutic range in the group after implementation (74.6% versus 28.3%, P < 0.001), with 1.6-fold higher Cavg (20.3 [17.0-22.2] mg/L versus 12.9 [11.3-17.0] mg/L, P < 0.001). Considering all Cavg during longitudinal therapeutic drug monitoring (TDM), the frequency of therapeutic Cavg was higher in the group after implementation (74.8% [n = 103] versus 31% [n = 116], P < 0.001). The dose optimization protocol was also associated with a reduced time to obtain a negative blood culture (P < 0.001) and fewer antibiotic switches (P = 0.025), without increasing the frequency of nephrotoxicity. Clinical outcomes also appeared to be improved, with less periventricular leukomalacia (P = 0.021), trended toward less respiratory instability (P = 0.15) and a shorter duration of vasoactive drug use (P = 0.18) for neonates receiving personalized doses of vancomycin. This personalized vancomycin dose protocol improves vancomycin exposure in neonates, with good safety, and suggests an improvement in biological and clinical outcomes.

Implementation of Vancomycin Therapeutic Monitoring Guidelines: Focus on Bayesian Estimation Tools in Neonatal and Pediatric Patients

BACKGROUND

The 2020 consensus guidelines for vancomycin therapeutic monitoring recommend using Bayesian estimation targeting the ratio of the area under the curve over 24 hours to minimum inhibitory concentration as an optimal approach to individualize therapy in pediatric patients. To support institutional guideline implementation in children, the objective of this study was to comprehensively assess and compare published population-based pharmacokinetic (PK) vancomycin models and available Bayesian estimation tools, specific to neonatal and pediatric patients.

METHODS

PubMed and Embase databases were searched from January 1994 to December 2020 for studies in which a vancomycin population PK model was developed to determine clearance and volume of distribution in neonatal and pediatric populations. Available Bayesian software programs were identified and assessed from published articles, software program websites, and direct communication with the software company. In the present review, 14 neonatal and 20 pediatric models were included. Six programs (Adult and Pediatric Kinetics, BestDose, DoseMeRx, InsightRx, MwPharm++, and PrecisePK) were evaluated.

RESULTS

Among neonatal models, Frymoyer et al and Capparelli et al used the largest PK samples to generate their models, which were externally validated. Among the pediatric models, Le et al used the largest sample size, with multiple external validations. Of the Bayesian programs, DoseMeRx, InsightRx, and PrecisePK used clinically validated neonatal and pediatric models.

CONCLUSIONS

To optimize vancomycin use in neonatal and pediatric patients, clinicians should focus on selecting a model that best fits their patient population and use Bayesian estimation tools for therapeutic area under the -curve-targeted dosing and monitoring.

Optimizing Vancomycin Dosing and Monitoring in Neonates and Infants Using Population Pharmacokinetic Modeling

We determined optimal vancomycin starting dose regimens in infants ≤180 days of age to achieve the highest probability of target attainment with an area under the concentration-time curve for 24 h (AUC₂₄) of ≥400 using population pharmacokinetic (PK) modeling. Secondarily, determination of the relationship between serum creatinine (SCR) and vancomycin clearance in neonates was done. A retrospective population PK study was designed and included pediatric patients ≤180 days old who had received vancomycin and had a serum vancomycin concentration sampled. A population PK model was developed using Pumas (v1.0.5). Simulation was performed with various dosing regimens to evaluate the probability of AUC₂₄ target attainment and probability of trough of ≤20 mg/liter, and comparison to published models was performed. Individual clearance estimates, obtained from the final model, were plotted against SCR and faceted by age quartiles to assess the relationship between SCR and vancomycin clearance. A total of 934 patients were included in the study (58.6% male; median age, 43.6 days [range of 0 to 184]; median number of concentration samples, 1 [range of 1 to 29]). A one-compartment model was developed with body weight (WT), SCR, and postmenstrual age (PMA) identified as significant covariates on clearance. Plotting vancomycin clearance versus SCR demonstrated no clear relationship between the two at <10 days postnatal age (PNA). Dosing regimens to attain AUC₂₄ and trough targets were stratified according to SCR for ≥10 days PNA and PMA for <10 days PNA. A vancomycin population PK model was developed for pediatric patients <180 days of age incorporating WT, SCR, and PMA. The relationship between vancomycin clearance and serum creatinine is not clear at <10 days PNA.

Dosing of vancomycin and target attainment in neonates: a systematic review

INTRODUCTION

Neonatal infections caused by Gram-positive bacteria are commonly treated with vancomycin. However, there is a lack of agreement on the optimal vancomycin dosing regimen and corresponding vancomycin exposure to correlate with efficacy and toxicity.

OBJECTIVES

This review aimed to evaluate dosing of vancomycin in neonates, therapeutic target attainment and clinical toxicity and efficacy outcomes.

METHODS

Two electronic databases - Embase and PubMed (Medline) - were systematically searched between 1995-2020. Studies that reported dosing regimens, drug concentrations, toxicity, and efficacy of vancomycin in neonates were eligible for inclusion. Descriptive analysis and a narrative synthesis were performed.

RESULTS

The systematic review protocol was registered with the PROSPERO International Prospective Register of Systematic reviews in 2020 (registration number: CRD42020219568). Twenty-four studies were included for final analysis. Overall, the data from the included studies showed a great degree of heterogeneity. Therapeutic drug monitoring practices were different between institutions. Although most studies used trough concentration with a target range of 10-20 mg/L, target attainment was different across the studies. The probability of target attainment was < 80% in all tested dosing algorithms. Few studies reported on vancomycin efficacy and toxicity.

CONCLUSION

This is a comprehensive overview of dosing strategies of vancomycin in neonates. There was inadequate evidence to propose an optimal therapeutic regimen in the newborn population, based on the data obtained, due to the heterogeneity in the design and objectives of the included studies. Consistent and homogeneous comparative randomised clinical trials are needed to identify a dosing regimen with a probability of target attainment of > 90% without toxicity.

Index for the appropriate vancomycin dosing in premature neonates and infants

BACKGROUND

In neonates, vancomycin (VCM) is used to treat Gram-positive bacterial infections. However, VCM blood concentrations are affected by gestational age, bodyweight (BW), and renal function. The initial VCM dose adjustment can therefore be difficult, and few reports have evaluated this issue. In this study, we investigated the factors determining the appropriate VCM dosing schedule in neonates, especially premature infants.

METHODS

The VCM dosage and trough concentrations were retrospectively investigated from the initial treatment to maintenance therapy in neonatal intensive care unit patients who underwent therapeutic drug monitoring. We examined the average single-administration VCM dosage during maintenance therapy. We then compared the actual VCM dose with that calculated using an index comprising six items that influence the VCM daily dose (postnatal age, gestational age, BW, serum creatinine level, urine output, and lactate level).

RESULTS

Twenty premature infants were included. The average BW of patients at the initial VCM administration was 975 g. During maintenance therapy, the average VCM dose was 8.4 mg/kg, and the median trough concentration was 12.4 μg/mL. When we applied the six-item index, 18 of 20 patients (90%) had concordant results between the actual VCM dosing schedule and the VCM calculated using the index.

CONCLUSIONS

The average VCM dose and six-item index can facilitate the transition from the initial VCM dose to an appropriate dose in many cases and contribute to early treatment in low-birthweight infants with more variable BW, distribution volumes, and renal function. In conclusion, our six-item index may help standardize VCM administration in premature infants.

Optimised versus standard dosing of vancomycin in infants with Gram-positive sepsis (NeoVanc): a multicentre, randomised, open-label, phase 2b, non-inferiority trial

BACKGROUND

Vancomycin is the most widely used antibiotic for neonatal Gram-positive sepsis, but clinical outcome data of dosing strategies are scarce. The NeoVanc programme comprised extensive preclinical studies to inform a randomised controlled trial to assess optimised vancomycin dosing. We compared the efficacy of an optimised regimen to a standard regimen in infants with late onset sepsis that was known or suspected to be caused by Gram-positive microorganisms.

METHODS

NeoVanc was an open-label, multicentre, phase 2b, parallel-group, randomised, non-inferiority trial comparing the efficacy and toxicity of an optimised regimen of vancomycin to a standard regimen in infants aged 90 days or younger. Infants with at least three clinical or laboratory sepsis criteria or confirmed Gram-positive sepsis with at least one clinical or laboratory criterion were enrolled from 22 neonatal intensive care units in Greece, Italy, Estonia, Spain, and the UK. Infants were randomly assigned (1:1) to either the optimised regimen (25 mg/kg loading dose, followed by 15 mg/kg every 12 h or 8 h dependent on postmenstrual age, for 5 ± 1 days) or the standard regimen (no loading dose; 15 mg/kg every 24 h, 12 h, or 8 h dependent on postmenstrual age for 10 ± 2 days). Vancomycin was administered intravenously via 60 min infusion. Group allocation was not masked to local investigators or parents. The primary endpoint was success at the test of cure visit (10 ± 1 days after the end of actual vancomycin therapy) in the per-protocol population, where success was defined as the participant being alive at the test of cure visit, having a successful outcome at the end of actual vancomycin therapy, and not having a clinically or microbiologically significant relapse or new infection requiring antistaphylococcal antibiotics for more than 24 h within 10 days of the end of actual vancomycin therapy. The non-inferiority margin was -10%. Safety was assessed in the intention-to-treat population. This trial is registered at ClinicalTrials.gov (NCT02790996).

FINDINGS

Between March 3, 2017, and July 29, 2019, 242 infants were randomly assigned to the standard regimen group (n=122) or the optimised regimen group (n=120). Primary outcome data in the per-protocol population were available for 90 infants in the optimised group and 92 in the standard group. 64 (71%) of 90 infants in the optimised group and 73 (79%) of 92 in the standard group had success at test of cure visit; non-inferiority was not confirmed (adjusted risk difference -7% [95% CI -15 to 2]). Incomplete resolution of clinical or laboratory signs after 5 ± 1 days of vancomycin therapy was the main factor contributing to clinical failure in the optimised group. Abnormal hearing test results were recorded in 25 (30%) of 84 infants in the optimised group and 12 (15%) of 79 in the standard group (adjusted risk ratio 1·96 [95% CI 1·07 to 3·59], p=0·030). There were six vancomycin-related adverse events in the optimised group (one serious adverse event) and four in the standard group (two serious adverse events). 11 infants in the intention-to-treat population died (six [6%] of 102 infants in the optimised group and five [5%] of 98 in the standard group).

INTERPRETATION

In the largest neonatal vancomycin efficacy trial yet conducted, no clear clinical impact of a shorter duration of treatment with a loading dose was demonstrated. The use of the optimised regimen cannot be recommended because a potential hearing safety signal was identified; long-term follow-up is being done. These results emphasise the importance of robust clinical safety assessments of novel antibiotic dosing regimens in infants.

FUNDING

EU Seventh Framework Programme for research, technological development and demonstration.

Variation in vancomycin dosing and therapeutic drug monitoring practices in neonatal intensive care units

Background Vancomycin is a frequently used antibiotic in neonates. However, there is no consensus guideline on the optimal dosing regimen and therapeutic drug monitoring (TDM) practices in this patient population. Objective To document the variability in the current dosing and TDM practices in neonatal intensive care units (NICU). Setting Belgian and Dutch NICUs. Method An online questionnaire was disseminated by e-mail to potential respondents. Main outcome measure Differences in vancomycin dosing and TDM practices in comparison with a reference source, the Dutch Paediatric Formulary. Results Eighteen NICUs (response rate 62%) participated. Eleven different dosing regimens are applied, with 83% using intermittent dosing regimens. Stratifying covariates used to determine the (initial) dosage include gestational age, postnatal age, serum creatinine, concurrent use of non-steroidal anti-inflammatory drugs, birth weight and current weight. Large variability is observed with regard to TDM practice as well, both for the concentration target range and the times of (re)sampling. Dosing calculators are more commonly used in the Netherlands than Belgium. Conclusion Significant inter-centre variability in dosing and TDM practices was found. The development of international consensus guidelines is required to optimize therapy. Dosing calculators to guide dosing are not yet considered as part of standard-of-care.

An Update on Population Pharmacokinetic Analyses of Vancomycin, Part II: In Pediatric Patients

Vancomycin is widely used in pediatric patients, however, large inter- and intraindividual variability are observed in vancomycin pharmacokinetics, affecting proper therapeutic monitoring. This review aimed at providing a comprehensive synthesis of the population pharmacokinetic models of vancomycin in pediatric patients and identifying potential factors responsible for the variability observed in various subpopulations. We conducted a literature search of the PubMed and EMBASE databases to obtain population pharmacokinetic studies for vancomycin published between January 2011 and January 2020, which resulted in a total of 33 studies. Vancomycin pharmacokinetics were generally characterized using a one-compartment model (n = 27), while a two-compartment model was used in six studies. The median (interquartile range) of the typical vancomycin clearance (CL) and the total volume of distribution adjusted to the median or mean body weight of the respective study was 0.103 L/h/kg (0.071-0.125) and 0.64 L/kg (0.59-1.03), respectively. Median weight-adjusted CL between different child age groups, such as infants and adolescents, did not appear to vary significantly, although the sample size for many age groups was very small. Examples of the conditions with relatively abnormal vancomycin pharmacokinetic values include renal insufficiency, sepsis, hematological and solid malignancy, and hypothermia treatment. Factors influencing pediatric vancomycin pharmacokinetics after adjusting for size and maturation include various renal function descriptors and some case-specific variables such as dialysate flow rate, ultrafiltrate output, and hypothermia. This review was able to document possible variables explaining the high variability observed in certain subpopulations and contrast vancomycin pharmacokinetics in different pediatric subpopulations.

Vancomycin Use in Children and Neonates across Three Decades: A Bibliometric Analysis of the Top-Cited Articles

Vancomycin is frequently prescribed in pediatrics, especially in intensive care unit settings, to treat Gram-positive bacterial infections. This work aims to collect the top-cited articles of pediatric and infectious diseases areas to gather the current evidence and gaps of knowledge on the use of vancomycin in these populations. The most relevant journals reported in the "pediatrics" and "infectious diseases" categories of the 2019 edition of Journal Citation Reports were browsed. Articles with more than 30 citations and published over the last three decades were collected. A bibliometric analysis was performed and 115 articles were retrieved. They were published in 21 journals, with a median impact factor of 4.6 (IQR 2.9-5.4). Sixty-eight of them (59.1%) belonged to "infectious diseases" journals. The most relevant topic was "bloodstream/complicated/invasive infections", followed by "antibiotic resistance/MRSA treatment". As for population distribution, 27 articles were on children only and 27 on neonates, most of which were from intensive care unit (ICU) settings. The current literature mainly deals with vancomycin as a treatment for severe infections and antibiotic resistance, especially in neonatal ICU settings. Lately, attention to new dosing strategies in the neonatal and pediatric population has become a sensible topic.

Continuous infusion of vancomycin improved therapeutic levels in term and preterm infants

BACKGROUND

Growing evidence suggests that continuous infusion of vancomycin (CIV) is superior to intermittent infusion of vancomycin (IIV) in neonates. This quality improvement (QI) project aimed to transition from IIV to CIV with earlier and improved attainment of therapeutic vancomycin levels.

METHODS

The Model for Improvement framework with Plan Do Study Act cycles was used. Prospective data were collected during three phases: IIV, CIV-1 and CIV-2.

INTERVENTIONS

A QI team developed a CIV drug monograph and a multidisciplinary education package.

RESULTS

Using IIV, 36% (9/25) of first vancomycin levels were within target range. CIV achieved therapeutic levels twice as quickly as IIV (p < 0.05) with improved first vancomycin target levels (IIV 36%, 9/25; CIV-1 55%, 16/29; CIV-2 61%, 14/23) and total therapeutic levels (IIV 44%, 37/84; CIV-1 56%, 55/98; CIV-2 69%, 79/114).

CONCLUSIONS

This QI project demonstrated a successful transition from IIV to CIV with reduced time to achieve target vancomycin and an increased proportion of therapeutic levels.

Population Pharmacokinetic Models of Vancomycin in Paediatric Patients: A Systematic Review

BACKGROUND

Vancomycin is commonly used to treat gram-positive bacterial infections in the paediatric population, but dosing can be challenging. Population pharmacokinetic (popPK) modelling can improve individualization of dosing regimens. The primary objective of this study was to describe popPK models of vancomycin and factors that influence pharmacokinetic (PK) variability in paediatric patients.

METHODS

Systematic searches were conducted in the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, International Pharmaceutical Abstracts and the grey literature without language or publication status restrictions from inception to 17 August 2020. Observational studies that described the development of popPK models of vancomycin in paediatric patients (< 18 years of age) were included. Risk of bias was assessed using the National Heart, Lung and Blood Institute Study Quality Assessment Tool for Case Series Studies.

RESULTS

Sixty-four observational studies (1 randomized controlled trial, 13 prospective studies and 50 retrospective studies of 9019 patients with at least 25,769 serum vancomycin concentrations) were included. The mean age was 2.5 years (range 1 day-18 years), serum creatinine was 47.1 ± 33.6 µmol/L, and estimated creatinine clearance was 97.4 ± 76 mL/min/1.73m². Most studies found that vancomycin PK was best described by a one-compartment model (71.9%). There was a wide range of clearance and volume of distribution (V_d) values (range 0.014-0.27 L/kg/h and 0.43-1.46 L/kg, respectively) with interindividual variability as high as 49.7% for clearance and 136% for V_d, proportional residual variability up to 37.5% and additive residual variability up to 17.5 mg/L. The most significant covariates for clearance were weight, age, and serum creatinine or creatinine clearance, and weight for V_d. Variable dosing recommendations were suggested.

CONCLUSION

Numerous popPK models of vancomycin were derived, however external validation of suggested dosing regimens and analyses in subgroup paediatric populations such as dialysis patients are still needed before a popPK model with best predictive performance can be applied for dosing recommendations. Significant intraindividual and interindividual PK variability was present, which demonstrated the need for ongoing therapeutic drug monitoring and derivation of PK models for vancomycin for certain subgroup populations, such as dialysis patients.

Low vancomycin trough concentration in neonates and young infants

BACKGROUND

Vancomycin (VCM) is useful for treating methicillin-resistant Staphylococcus aureus. In infants, calibrating the initial VCM dose is difficult, and many regimens have been proposed. For instance, our center uses the VCM regimen recommended for infants in the 2012-13 Nelson's Pediatric Antimicrobial Therapy. Nonetheless, our experience has shown that the initial VCM trough concentrations were frequently off target. We therefore analyzed the data on the initial VCM trough concentration in infant patients at our center.

METHODS

The study subjects were inborn infants born between July 2014 and June 2019 who were given VCM at earlier than day 60 in the neonatal intensive care unit. The primary outcome was the initial VCM trough concentration. The patients were divided into three groups by VCM trough concentration: <10, 10-15, and >15 mg/L. We also estimated VCM trough concentration by one method using Monte Carlo simulation, based on Nelson regimen dosage.

RESULTS

Thirty-three patients were analyzed. The number of patients with <10, 10-15, and >15 mg/L was 24, 4, and 5, respectively. There was no significant difference in clinical characteristics between <10 versus 10-15 and 10-15 versus >15 mg/L. The numbers of patients with <10, 10-15, and >15 mg/L in the simulation were 26, 6, and 1, respectively.

CONCLUSIONS

Most initial VCM trough concentrations were below the target. We could not find any significant clinical characteristics, which affected VCM trough concentration. Increasing the VCM dosage of the Nelson regimen with simulation should therefore be considered.

Target Attainment and Clinical Efficacy for Vancomycin in Neonates: Systematic Review

Vancomycin is commonly used as a treatment for neonatal infections. However, there is a lack of consensus establishing the optimal vancomycin therapeutic regimen and defining the most appropriate PK/PD parameter correlated with the efficacy. A recent guideline recommends AUC–guided therapeutic dosing in treating serious infections in neonates. However, in clinical practice, trough serum concentrations are commonly used as a surrogate PKPD index for AUC24. Despite this, target serum concentrations in a neonatal population remain poorly defined. The objective is to describe the relationship between therapeutic regimens and the achievement of clinical or pharmacokinetic outcomes in the neonatal population. The review was carried out following PRISMA guidelines. A bibliographic search was manually performed for studies published on PubMed and EMBASE. Clinical efficacy and/or target attainment and the safety of vancomycin treatment were evaluated through obtaining serum concentrations. A total of 476 articles were identified, of which 20 met the inclusion criteria. All of them evaluated the target attainment, but only two assessed the clinical efficacy. The enormous variability concerning target serum concentrations is noteworthy, which translates into a difficulty in determining which therapeutic regimen achieves the best results. Moreover, there are few studies that analyze clinical efficacy results obtained after reaching predefined trough serum concentrations, this information being essential for clinical practice.

Serum Creatinine and Serum Cystatin C are Both Relevant Renal Markers to Estimate Vancomycin Clearance in Critically Ill Neonates

Purpose: Serum creatinine (SCr) is used as a marker of kidney function to guide dosing of renally eliminated drugs. Serum Cystatin C (S-CysC) has been suggested as a more reliable kidney marker than SCr in adults and children. Purpose of this study was to investigate S-CysC as alternative renal marker to SCr for estimating vancomycin clearance in neonates undergoing intensive care.

Methods: Vancomycin pharmacokinetics (PK), SCr and S-CysC data were collected in patients undergoing vancomycin treatment in the neonatal intensive care unit of Robert Debré Hospital - Paris. A population PK analysis was performed utilizing routine therapeutic drug monitoring samples. S-CysC and SCr were compared as covariates on vancomycin clearance using stepwise covariate modeling (forward inclusion [p < 0.05] and backward elimination [p < 0.01]). Model performance was evaluated by graphical and statistical criteria.

Results: A total of 108 vancomycin concentrations from 66 patients (postmenstrual age [PMA] of 26–46 weeks) were modeled with an allometric one-compartment model. The median (range) values for SCr and S-CysC were 41 (12–153) µmol/l and 1.43 (0.95–2.83) mg/l, respectively. Following stepwise covariate model building, SCr was retained as single marker of kidney function (after accounting for weight and PMA) in the final model. Compared to the final model based on SCr, the alternative model based on S-CysC showed very similar performance (e.g. BIC of 578.3 vs. 576.4) but included one additional covariate: impact of mechanical ventilation on vancomycin clearance, in addition to the effects of size and maturation.

Conclusion: ill neonates. However, if using S-CysC for this purpose mechanical ventilation needs to be taken into account.

External Evaluation of Vancomycin Population Pharmacokinetic Models at Two Clinical Centers

Background: Numerous vancomycin population pharmacokinetic models in neonates have been published; however, their predictive performances remain unknown. This study aims to evaluate their external predictability and explore the factors that might affect model performance. Methods: Published population pharmacokinetic models in neonates were identified from the literature and evaluated using datasets from two clinical centers, including 171 neonates with a total of 319 measurements of vancomycin levels. Predictive performance was assessed by prediction- and simulation-based diagnostics and Bayesian forecasting. Furthermore, the effect of model structure and a number of identified covariates was also investigated. Results: Eighteen published pharmacokinetic models of vancomycin were identified after a systematic literature search. Using prediction-based diagnostics, no model had a median prediction error of ≤ ± 15%, a median absolute prediction error of ≤30%, and a percentage of prediction error that fell within ±30% of >50%. A simulation-based visual predictive check of most models showed there were large deviations between observations and simulations. After Bayesian forecasting with one or two prior observations, the predicted performance improved significantly. Weight, age, and serum creatinine were identified as the most important covariates. Moreover, employing a maturation model based on weight and age as well as nonlinear model to incorporate serum creatinine level significantly improved predictive performance. Conclusion: The predictability of the pharmacokinetic models for vancomycin is closely related to the approach used for modeling covariates. Bayesian forecasting can significantly improve the predictive performance of models.

Individualized Vancomycin Dosing with Therapeutic Drug Monitoring and Pharmacokinetic Consultation Service: A Large-Scale Retrospective Observational Study

Background

To date, outcome data with a large sample size and data regarding the clinical outcomes of pharmacokinetic-guided (PK) dosing of vancomycin are limited.

Aim

We evaluated the pharmacokinetic and clinical outcomes of a PK-guided dosing advisory program, pharmacokinetic consultation service (PKCS), in vancomycin treatment.

Methods

We investigated vancomycin therapeutic drug monitoring (TDM) and PKCS use through a retrospective review of patients who had serum vancomycin trough concentration data from October 2017 to November 2018. Among these patients, we selected non-critically ill adult patients satisfying our selection criteria to evaluate the effect of PKCS. Target trough attainment rate, time to target attainment, vancomycin-induced nephrotoxicity (VIN), vancomycin treatment failure rate, and duration of vancomycin therapy were compared between patients whose dosing was adjusted according to PKCS (PKCS group), and those whose dose was adjusted at the discretion of the attending physician (non-PKCS group).

Results

A total of 280 patients met the selection criteria for the VIN analysis (PKCS, n=134; non-PKCS, n=146). The incidence of VIN was similar between the two groups (PKCS, n=5; non-PKCS, n=5); however, the target attainment rate was higher in the PKCS group (75% vs 60%, P = 0.012). The time to target attainment was similar between the two groups. Further exclusions yielded 112 patients for the clinical outcome evaluation (PKCS, n=51; non-PKCS, n=61). The treatment failure rate was similar, and the duration of vancomycin therapy was longer in the PKCS group (12 vs 8 days, P = 0.008).

Conclusion

In non-critically ill patients, an increase in target trough achieved by PKCS did not lead to decreased vancomycin treatment failures, shorter vancomycin treatment, or decreased nephrotoxicity in vancomycin treatment. Considering the excessive amount of effort currently put into vancomycin dosing and monitoring, more selective criteria for individualized pharmacokinetic-guided dosing needs to be applied.

Population Pharmacokinetic Analysis and Dose Regimen Optimization in Japanese Infants with an Extremely Low Birth Weight

Vancomycin is a synthetic antibiotic effective against Gram-positive pathogens. Although the clinical applicability of vancomycin for infants has been increasing, the pharmacokinetic data for vancomycin in extremely low-birth-weight infants are limited. The aim of this study was to construct a population pharmacokinetics model for vancomycin in extremely-low-birth-weight infants and establish an optimal dosage regimen. We enrolled children aged less than 1 year with a birth weight of less than 1,000 g and body weight at vancomycin prescription of less than 1,500 g. Pharmacokinetic data from 19 patients were analyzed, and a population pharmacokinetics model was developed using nonlinear mixed-effects modeling software. Goodness-of-fit plots, a nonparametric bootstrap analysis, and a prediction-corrected visual predictive check were employed to evaluate the final model. The dosage regimen was optimized based on the final model. The pharmacokinetic data fit a one-compartment model with first-order elimination, and body weight and estimated serum creatinine level were used as significant covariates. In a simulation using the final model, the optimal dosage regimen, especially when the serum creatinine level (>0.6 mg/dl) was high, was 5.0 to 7.5 mg/kg of body weight twice a day every 12 h; this was required to reduce the dosage compared with that in previous studies. The recommended doses based on the current target time course concentration curves may not be appropriate for extremely-low-birth-weight infants.

Model-Informed Precision Dosing of Antibiotics in Pediatric Patients: A Narrative Review

Optimal pharmacotherapy in pediatric patients with suspected infections requires understanding and integration of relevant data on the antibiotic, bacterial pathogen, and patient characteristics. Because of age-related physiological maturation and non-maturational covariates (e.g., disease state, inflammation, organ failure, co-morbidity, co-medication and extracorporeal systems), antibiotic pharmacokinetics is highly variable in pediatric patients and difficult to predict without using population pharmacokinetics models. The intra- and inter-individual variability can result in under- or overexposure in a significant proportion of patients. Therapeutic drug monitoring typically covers assessment of pharmacokinetics and pharmacodynamics, and concurrent dose adaptation after initial standard dosing and drug concentration analysis. Model-informed precision dosing (MIPD) captures drug, disease, and patient characteristics in modeling approaches and can be used to perform Bayesian forecasting and dose optimization. Incorporating MIPD in the electronic patient record system brings pharmacometrics to the bedside of the patient, with the aim of a consisted and optimal drug exposure. In this narrative review, we evaluated studies assessing optimization of antibiotic pharmacotherapy using MIPD in pediatric populations. Four eligible studies involving amikacin and vancomycin were identified from 418 records. Key articles, independent of year of publication, were also selected to highlight important attributes of MIPD. Although very little research has been conducted until this moment, the available data on vancomycin indicate that MIPD is superior compared to conventional dosing strategies with respect to target attainment. The utility of MIPD in pediatrics needs to be further confirmed in frequently used antibiotic classes, particularly aminoglycosides and beta-lactams.

Assessment of Vancomycin Pharmacokinetics and Dose Regimen Optimisation in Preterm Neonates

BACKGROUND

The pharmacokinetics of vancomycin, a drug used for the treatment of methicillin-resistant Staphylococcus aureus (MRSA), varies between paediatric and adult patients.

OBJECTIVE

The objective of this study was to assess the pharmacokinetics of vancomycin in preterm neonates and determine the optimum dose regimen.

METHODS

This was a randomised double-blind study of preterm neonates admitted to neonatal intensive care units. They all received vancomycin 15 mg/kg every 12 h. Blood was sampled just before administration of the third, sixth and ninth vancomycin dose. Pharmacokinetic parameters were estimated using a Bayesian approach implemented in Monolix 2018R2 software. Covariates assessed included postmenstrual age, current weight, creatinine clearance, albumin, gestational age, body surface area and current age. We used Monte Carlo simulations for dose regimen optimisation targeting area under the concentration-time curve up to 24 h (AUC_0-24h) of ≥ 400 mg × h/L.

RESULTS

In total, 19 preterm neonates were enrolled in the study with a median age of 14 (3-58) days. A one-compartment model with linear elimination best described the pharmacokinetics of vancomycin. Volume of distribution and clearance was 0.88 L and 0.1 L/h, respectively, for a typical neonate weighing 1.48 kg. Simulation of the current dose regimen showed that 27.5% of the neonates would achieve the target AUC_0-24h of ≥ 400 mg × h/L, and 70.7% of the neonates would achieve it with 12 mg/kg every 8 h.

CONCLUSION

The majority of the neonates were under dosed. Vancomycin 12 mg/kg should be administered every 8 h over 1 h infusion to improve the likelihood of achieving the AUC_0-24h target of ≥ 400 mg × h/L. This target is considered optimal for MRSA infections, where the vancomycin minimum inhibitory concentration is ≤ 1 µg/mL.

Population pharmacokinetic meta-analysis of individual data to design the first randomized efficacy trial of vancomycin in neonates and young infants

OBJECTIVES

In the absence of consensus, the present meta-analysis was performed to determine an optimal dosing regimen of vancomycin for neonates.

METHODS

A 'meta-model' with 4894 concentrations from 1631 neonates was built using NONMEM, and Monte Carlo simulations were performed to design an optimal intermittent infusion, aiming to reach a target AUC0-24 of 400 mg·h/L at steady-state in at least 80% of neonates.

RESULTS

A two-compartment model best fitted the data. Current weight, postmenstrual age (PMA) and serum creatinine were the significant covariates for CL. After model validation, simulations showed that a loading dose (25 mg/kg) and a maintenance dose (15 mg/kg q12h if <35 weeks PMA and 15 mg/kg q8h if ≥35 weeks PMA) achieved the AUC0-24 target earlier than a standard 'Blue Book' dosage regimen in >89% of the treated patients.

CONCLUSIONS

The results of a population meta-analysis of vancomycin data have been used to develop a new dosing regimen for neonatal use and to assist in the design of the model-based, multinational European trial, NeoVanc.

Development and external evaluation of a population pharmacokinetic model for continuous and intermittent administration of vancomycin in neonates and infants using prospectively collected data

BACKGROUND

Vancomycin is commonly used for nosocomial bacterial pathogens causing late-onset septicaemia in preterm infants. We prospectively collected pharmacokinetic data aiming to describe pharmacokinetics and determine covariates contributing to the variability in neonatal vancomycin pharmacokinetics. Further, we aimed to use the model to compare the ratio of AUC24 at steady-state to the MIC (AUC24,ss/MIC) of several intermittent and continuous dosing regimens.

METHODS

Newborns receiving vancomycin for suspected or confirmed late-onset sepsis were included. Peak and trough concentrations for intermittent vancomycin dosing and steady-state concentrations for continuous vancomycin dosing were measured. NONMEM 7.3 was used for population pharmacokinetic analysis. Monte Carlo simulations were performed to compare dosing schemes.

RESULTS

Data from 54 infants were used for model development and from 34 infants for the model evaluation {corrected gestational age [median (range)] = 29 (23.7-41.9) weeks and 28 (23.4-41.7) weeks, respectively}. The final model was a one-compartment model. Weight and postmenstrual age were included a priori, and then no additional covariate significantly improved the model fit. Final model parameter estimates [mean (SEM)]: CL = 5.7 (0.3) L/h/70 kg and V = 39.3 (3.7) L/70 kg. Visual predictive check of the evaluation dataset confirmed the model can predict external data. Simulations using MIC of 1 mg/L showed that for neonates with gestational age ≤25 weeks and postnatal age ≤2 weeks AUC24,ss/MIC was lower with the intermittent regimen (median 482 versus 663).

CONCLUSIONS

A population pharmacokinetic model for continuous and intermittent vancomycin administration in infants was developed. Continuous administration might be favourable for treating infections caused by resistant microorganisms in very young and immature infants.

Optimizing Antibiotic Treatment Strategies for Neonates and Children: Does Implementing Extended or Prolonged Infusion Provide any Advantage?

Optimizing the use of antibiotics has become mandatory, particularly for the pediatric population where limited options are currently available. Selecting the dosing strategy may improve overall outcomes and limit the further development of antimicrobial resistance. Time-dependent antibiotics optimize their free concentration above the minimal inhibitory concentration (MIC) when administered by continuous infusion, however evidences from literature are still insufficient to recommend its widespread adoption. The aim of this review is to assess the state-of-the-art of intermittent versus prolonged intravenous administration of antibiotics in children and neonates with bacterial infections. We identified and reviewed relevant literature by searching PubMed, from 1 January 1 2000 to 15 April 2020. We included studies comparing intermittent versus prolonged/continuous antibiotic infusion, among the pediatric population. Nine relevant articles were selected, including RCTs, prospective and retrospective studies focusing on different infusion strategies of vancomycin, piperacillin/tazobactam, ceftazidime, cefepime and meropenem in the pediatric population. Prolonged and continuous infusions of antibiotics showed a greater probability of target attainment as compared to intermittent infusion regimens, with generally good clinical outcomes and safety profiles, however its impact in terms on efficacy, feasibility and toxicity is still open, with few studies led on children and adult data not being fully extendable.

Practice survey on the use of vancomycin in pediatrics in the New Aquitaine region and guidelines of learned societies

INTRODUCTION

Vancomycin is an old antibiotic whose use is still being debated today. The objective of this work was to establish an inventory of the use of vancomycin in the various pediatric and neonatal hospital services in the New Aquitaine region.

MATERIALS AND METHODS

A declaratory practice survey was conducted in 49 pediatric and neonatal hospital units. These practices were compared with the guidelines of several learned societies.

RESULTS

A total of 36 responses could be analyzed: 12 units (33%) used vancomycin in discontinuous administration, 18 (50%) had opted for continuous infusion, and six used it in both modalities (17%). The reported dosages were highly variable. Blood tests were performed by 26 units (72%), but the target values of the trough serum concentration were also highly variable. After dosing, all units reported adjusting the dosage and re-dosing after modification (26/26). Finally, 21 units (58%) reported taking into account the MIC of the possibly isolated bacterium.

CONCLUSION

Our study shows that vancomycin is used in very different ways from one unit to another, within the same region, including in ways not recommended by the main learned societies. Much work remains to be done to determine the optimal dosages of vancomycin in pediatrics, to set the serum trough concentration of vancomycin values, and to determine whether continuous infusion use is comparable to discontinuous administration in terms of efficacy.

Continuous Infusion Vancomycin in Pediatric Patients: A Critical Review of the Evidence

OBJECTIVE

To evaluate the use of continuous infusion vancomycin in pediatric patients.

DATA SOURCES AND STUDY SELECTION

PubMed, Cochrane Library, International Pharmaceutical Abstracts, and Google Scholar were searched to identify relevant published articles (1977 to November 2019) using the following search terms: vancomycin, neonates, pediatrics, infusion, continuous, administration, children, nephrotoxicity, pharmacokinetics, and pharmacodynamics. All English-language primary references that evaluated continuous infusion vancomycin in pediatric patients were included in this review.

DATA SYNTHESIS

Vancomycin is typically administered with intermittent infusions, but continuous infusion is an alternative delivery method used to improve achievement of target serum concentrations. Fifteen articles were reviewed that evaluated continuous infusion vancomycin in pediatric patients. Study data were heterogeneous with limited evidence to support improved clinical or microbiologic outcomes as compared with intermittent dosing. Potential benefits and limitations of continuous infusions are discussed.

CONCLUSIONS

Currently available evidence is lacking to support routine implementation of continuous infusion vancomycin in pediatric patients. However, it is a therapeutic option in certain clinical conditions and could be beneficial for individuals with serious Gram-positive infections where rapid achievement of target serum concentrations is critical. Continuous infusions may also benefit individuals who do not achieve target concentrations or who experience significant red man syndrome with traditional dosing, particularly when high daily doses are required. Optimal dosing and ideal target serum concentrations have not been established and may vary for different populations. Future prospective randomized clinical trials should be performed to identify optimal dosing and monitoring regimens and determine comparative safety and efficacy with traditional intermittent dosing in various pediatric populations.

The Benefit of Individualized Vancomycin Dosing Via Pharmacokinetic Tools: A Systematic Review and Meta-analysis

Background: Various pharmacokinetic (PK) equations and software have been developed to individualize vancomycin dosing. However, the benefit of using any PK information to guide vancomycin dosing has not been fully elucidated. Objective: To appraise available evidence on the effectiveness and safety of individualized vancomycin dosing via PK tools. Methods: PubMed, EMBASE, the Cochrane Library, and 2 Chinese literature databases were searched through August 1, 2019. Randomized controlled trials (RCTs) and cohort studies that reported the PK and clinical outcomes of individualized vancomycin dosing versus empirical dosing were included. Pooled risk ratios (RRs) and mean differences were calculated for dichotomous and continuous outcomes, respectively. Results: A total of 21 studies involving 4346 patients were finally included, of which 3 were RCTs and 18 were cohort studies. Meta-analysis revealed that PK-guided vancomycin dosing significantly increased the attainment of target trough concentration (RR = 1.59; 95% CI = 1.49-1.70) and decreased the incidence of nephrotoxicity (RR = 0.57; 95% CI = 0.46-0.71). Additionally, the available evidence showed that target area under the curve/minimum inhibitory concentration attainment rate and time to target concentration could improve. However, the evidence on clinical outcomes was scarce, and no significant differences were detected in clinical response rate, microbiological eradication rate, mortality, and length of hospital stay between PK-guided vancomycin dosing and empirical dosing strategies. Conclusion and Relevance: Individualized vancomycin dosing via PK tools significantly increases the attainment of target trough concentration and decreases the incidence of nephrotoxicity. Evidence on clinical effectiveness was limited and showed no significant benefit. Further well-designed studies are warranted to assess its clinical effectiveness and inform routine care.

Optimizing Antibiotic Drug Therapy in Pediatrics: Current State and Future Needs

The selection of the right antibiotic and right dose necessitates clinicians understand the contribution of pharmacokinetic variability stemming from age-related physiologic maturation and the pharmacodynamics to optimize drug exposure for clinical response. The complexity of selecting the right dose arises from the multiplicity of pediatric age groups, from premature neonates to adolescents. Body size and age (which relate to organ function) must be incorporated to optimize antibiotic dosing in this vulnerable population. In the effort to optimize and individualize drug dosing regimens, clinical pharmacometrics that incorporate population-based pharmacokinetic modeling, Bayesian estimation, and Monte Carlo simulations are utilized as a quantitative approach to understanding and predicting the pharmacology and clinical and microbiologic efficacy of antibiotics. In addition, opportunistic study designs and alternative blood sampling strategies can serve as practical approaches to ensure successful conduct of pediatric studies. This review article examines relevant literature on optimization of antibiotic pharmacotherapy in pediatric populations published within the last decade. Specific pediatric antibiotic data, including beta-lactam antibiotics, aminoglycosides, and vancomycin, are critically evaluated.

Pharmacokinetic modelling and Bayesian estimation-assisted decision tools to optimize vancomycin dosage in neonates: only one piece of the puzzle

Introduction: Vancomycin is commonly administered to neonates, while observational data on therapeutic drug monitoring (TDM, trough levels) suggest that vancomycin exposure and dosage remain substandard. Area covered: Data on vancomycin pharmacokinetics (PK) and its covariates are abundant. Consequently, modeling is an obvious tool to improve targeted exposure, with a shift from TDM trough levels to area under the curve (AUC_24h) targets, as in adults. Continuous administration appeared as a practice to facilitate AUC_24h target attainment, while Bayesian model-supported targeting emerged as a novel tool. However, the AUC_24h/MIC (minimal inhibitory concentration) target itself should consider neonate-specific aspects (bloodstream infections, coagulase-negative staphylococci, protein binding, underexplored causes of variability, like assays, preparation and administration inaccuracies, or missing covariates). Expert opinion: To improve targeted exposure in neonates, initial vancomycin prescription should be based on 'a priori model-based individual dosing' using validated dosing regimens, followed by further tailoring by dosing optimization applying Bayesian estimation-assisted TDM. Future research should focus on the feasibility to integrate these tools (individualized dosing, Bayesian models) in clinical practice, and to perform PK/PD studies in the relevant animal models and human neonatal setting (coagulase-negative staphylococci, bloodstream infections).

The Effectiveness of a Vancomycin Dosing Guideline in the Neonatal Intensive Care Unit for Achieving Goal Therapeutic Trough Concentrations

Concern for bacterial resistance and treatment failure with vancomycin trough concentrations < 10 μg/mL have led guidelines to increase goal concentrations. There is a paucity of data evaluating vancomycin dosage necessary to achieve goals in the neonatal intensive care unit (NICU). We aimed to evaluate the implementation of a new vancomycin dosing guideline in improving trough target attainment. This retrospective study evaluated neonates in the NICU treated with vancomycin between January 2009 and December 2015. Therapeutic trough concentration attainment (10-20 μg/mL) was compared between neonates receiving vancomycin per old versus new dosing guidelines. Vancomycin trough concentrations, modeled pharmacodynamic target attainment, and nephrotoxicity were compared between groups. A total of 212 vancomycin trough concentrations (n = 91 old and n = 121 new guideline) were evaluated in 182 unique neonates. The mean ± standard deviation trough concentration achieved was 18.0 ± 7.3 μg/mL vs 8.9 ± 4.8 μg/mL in the new and old guidelines, respectively (P < .01). The new guideline resulted in a higher percentage of neonates achieving trough concentrations of 10 to 20 μg/mL (62% vs 29%; P < .01) and decreased the percentage of neonates with subtherapeutic trough concentrations (9% vs 69%; P < .01). Pharmacokinetic modeling identified postmenstrual age, days of life, and urine output as predictors of vancomycin clearance and resultant trough and area under the curve values (P < .01 for all). Trough concentrations >10 μg/mL ensured area under the curve /minimum inhibitory concentration >400 in >90% of neonates when bacteria minimum inhibitory concentration was ≤ 1 μg/mL. Nephrotoxicity was similar between groups (8.3% vs 7.7%; P = .99). In conclusion, a vancomycin nomogram designed to achieve trough concentration of 10 to 20 μg/mL improves pharmacodynamic target attainment in neonates in the NICU.

Continuous-Infusion Vancomycin in Neonates: Assessment of a Dosing Regimen and Therapeutic Proposal

Introduction: Vancomycin remains the reference antibiotic in neonates for care-related infections caused by ß-lactam-resistant Gram-positive bacteria. Achieving the optimal serum vancomycin level is challenging because of high inter-individual variability and the drug's narrow therapeutic window. Continuous infusion might offer pharmacokinetic and practical advantages, but we lack consensus on the dosing regimen. The aim was to determine the proportion of neonates achieving an optimal therapeutic vancomycin level at the first vancomycin concentration assay and which dosing regimen is the most suitable for neonates. Methods: All neonates receiving continuous-infusion vancomycin (loading dose 15 mg/kg and maintenance dose 30 mg/kg/d) in a neonatal intensive care unit were retrospectively analyzed. The proportion of neonates reaching the target serum vancomycin level was calculated. After reviewing the literature to identify all published articles proposing a dosing regimen for continuous-infusion vancomycin for neonates, regimens were theoretically applied to our population by using maintenance doses according to covariate(s) proposed in the original publication. Results: Between January 2013 and December 2014, 75 neonates received 91 vancomycin courses by continuous infusion. Median gestational age, birth weight, and postnatal age were 27 weeks (interquartile range 26-30.5), 815 g (685-1,240), and 15 days (9-33). At the first assay, only 28/91 (30.8%) courses resulted in vancomycin levels between 20 and 30 mg/L (target level), 23/91 (25.3%) >30 mg/L and 40/91 (43.9%) <20 mg/L. We applied six published dosing regimens to our patients. One of these dosing regimens based on corrected gestational age (CGA) and serum creatinine level (SCR) would have allowed us to prescribe lower doses to neonates with high vancomycin levels and higher doses to neonates with low levels. Conclusions: A simplified dosing regimen of continuous-infusion vancomycin did not achieve therapeutic ranges in neonates; a patient-tailored dosing regimen taking into account CGA and SCR level or an individualized pharmacokinetic model can help to anticipate the inter-individual variability in neonates and would have been more suitable.

Antimicrobial Stewardship in the Neonatal Intensive Care Unit: An Update

Neonates represent a vulnerable population for infections and neonatal sepsis is a major cause of mortality and morbidity worldwide. Therefore, antimicrobials are the most commonly prescribed drugs in the Neonatal Intensive Care Unit Setting but unfortunately are quite often used inappropriately with various short and long-term effects. The rational use of antimicrobials is of paramount importance in this population and structured antimicrobial stewardship interventions should be in place. These interventions are slightly different from those used in adults and older children due to the particularities of the neonatal medicine. The aim of this review is to provide an update in the field and identify areas for further consideration and future research.

Protocol for a randomised controlled trial of continuous infusions of vancomycin to improve the attainment of target vancomycin levels in young infants: The VANC trial

INTRODUCTION

Vancomycin is frequently used in the treatment of late-onset sepsis in young infants and is routinely administered as intermittent infusions (IIV); however, existing IIV dosing guidelines achieve target vancomycin levels in less than half of infants. Continuous infusions of vancomycin (CIV) are an attractive alternative as adult studies report a higher attainment of target vancomycin levels, simpler drug monitoring and fewer drug side effects.

METHODS

This is a multicentre, randomised controlled trial in which 200 young infants (aged 0-90 days) requiring vancomycin will be randomised to CIV or IIV for a duration determined by the treating clinician. Vancomycin levels will be measured immediately after the first dose in both arms. Trough and peak levels will be determined in the IIV arm and steady-state levels 18-30 hours after commencement of infusion will be measured in the CIV arm. Full blood count, urea and electrolytes, and C reactive protein level will be monitored throughout treatment. For all Gram-positive bacteria isolated from blood culture, a vancomycin Etest will be done to determine the minimum inhibitory concentration of the bacterium.

ANALYSIS

Primary outcome: the proportion of infants with levels within target range at their first steady-state concentration.

SECONDARY OUTCOMES

(1) the proportion of drug-related adverse effects; (2) the time to achieve target levels in the blood; (3) the pharmacodynamics of vancomycin (using non-linear mixed effect modelling).

ETHICS AND DISSEMINATION

The study has been approved by The Royal Children's Hospital Melbourne Human Research Ethics Committee (HREC) (No. 34030) and the South Eastern Sydney Local Health District HREC (SSA 16/G/335). Results will be published in a peer-reviewed journal.

TRIAL REGISTRATION NUMBER

NCT02210169.

Vancomycin therapeutic drug monitoring and population pharmacokinetic models in special patient subpopulations

Vancomycin is a fundamental antibiotic in the management of severe Gram-positive infections. Inappropriate vancomycin dosing is associated with therapeutic failure, bacterial resistance and toxicity. Therapeutic drug monitoring (TDM) is acknowledged as an important part of the vancomycin therapy management, at least in specific patient subpopulations, but implementation in clinical practice has been difficult because there are no consensus and agglutinator documents. The aims of the present work are to present an overview of the current knowledge on vancomycin TDM and population pharmacokinetic (PPK) models relevant to specific patient subpopulations. Based on three published international guidelines (American, Japanese and Chinese) on vancomycin TDM and a bibliographic review on available PPK models for vancomycin in distinct subpopulations, an analysis of evidence was carried out and the current knowledge on this topic was summarized. The results of this work can be useful to redirect research efforts to address the detected knowledge gaps. Currently, TDM of vancomycin presents a moderate level of evidence and practical recommendations with great robustness in neonates, pediatric and patients with renal impairment. However, it is important to investigate in other subpopulations known to present altered vancomycin pharmacokinetics (eg neurosurgical, oncological and cystic fibrosis patients), where evidence is still unsufficient.

Population Pharmacokinetics of Vancomycin in Chinese ICU Neonates: Initial Dosage Recommendations

The main goal of our study was to characterize the population pharmacokinetics of vancomycin in critically ill Chinese neonates to develop a pharmacokinetic model and investigate factors that have significant influences on the pharmacokinetics of vancomycin in this population. The study population consisted of 80 neonates in the neonatal intensive care unit (ICU) from which 165 trough and peak concentrations of vancomycin were obtained. Nonlinear mixed effect modeling was used to develop a population pharmacokinetic model for vancomycin. The stability and predictive ability of the final model were evaluated based on diagnostic plots, normalized prediction distribution errors and the bootstrap method. Serum creatinine (Scr) and body weight were significant covariates on the clearance of vancomycin. The average clearance was 0.309 L/h for a neonate with Scr of 23.3 μmol/L and body weight of 2.9 kg. No obvious ethnic differences in the clearance of vancomycin were found relative to the earlier studies of Caucasian neonates. Moreover, the established model indicated that in patients with a greater renal clearance status, especially Scr < 15 μmol/L, current guideline recommendations would likely not achieve therapeutic area under the concentration-time curve over 24 h/minimum inhibitory concentration (AUC24h/MIC) ≥ 400. The exceptions to this are British National Formulary (2016-2017), Blue Book (2016) and Neofax (2017). Recommended dose regimens for neonates with different Scr levels and postmenstrual ages were estimated based on Monte Carlo simulations and the established model. These findings will be valuable for developing individualized dosage regimens in the neonatal ICU setting.