Continuous infusion of vancomycin in neonates

Association between Vancomycin Pharmacokinetic Parameters and Clinical and Microbiological Efficacy in a Cohort of Neonatal Patients

Vancomycin pharmacokinetic/pharmacodynamic (PK/PD) targets have not been validated in the neonatal population as no specifically designed studies are available. The main goal of this study was to analyze the therapeutic vancomycin regimen, the 24-h area under the curve (AUC₂₄), and the trough plasma concentration (C_t) obtained that achieved clinical and microbiological effectiveness in a cohort of neonates. This was an observational, prospective, single-center study covering a period of 2 years. Eligible patients were neonates and young infants who were undergoing treatment with intravenous vancomycin for ≥72 h with ≥1 C_t available. The primary outcome was the association of C_t and AUC₂₄ with clinical and microbiological efficacy at the beginning (early clinical evolution [ECE]) and the end (late clinical evolution [LCE]) of treatment with vancomycin. A total of 43 patients were included, 88.4% of whom were cured. In ECE, the cutoff points of the receiver operating characteristic (ROC) curve were 238 mg · h/L (sensitivity of 61% and specificity of 88%) for AUC₂₄ and 6.8 μg/mL (sensitivity of 61% and specificity of 92%) for C_t. In LCE, the C_t value was 11 μg/mL, with a sensitivity of 80% and a specificity of 92%. In this analysis, AUC₂₄ was not considered a good predictor. Logistic regression showed that a vancomycin C_t of ≤6.8 μg/mL was associated with an unfavorable ECE (P = 0.001), being 18 times more likely to progress poorly compared to those with higher levels. AUC₂₄ and C_t are good predictors of ECE in this population. Concentrations close to 7 μg/mL and an AUC₂₄ of around 240 mg · h/L 48 h after antibiotic initiation seem to be sufficient to achieve clinical cure in most cases.

An Audit to Evaluate Vancomycin Therapeutic Drug Monitoring in a Neonatal Intensive Care Unit

BACKGROUND

Therapeutic drug monitoring (TDM) is routinely used for optimization of vancomycin therapy, because of exposure-related efficacy and toxicity, in addition to significant variability in pharmacokinetics, which leads to unpredictable drug exposure.

OBJECTIVE

The aim of this study was to evaluate target attainment and TDM of vancomycin in neonates.

METHODS

The authors conducted a retrospective study and collected data from medical records of all neonates who received vancomycin therapy in the neonatal intensive care unit between January 2019 and December 2019. The primary outcome was the proportion of vancomycin courses that reached target trough concentrations of 10-20 mg/L based on appropriate TDM samples collection. Secondary outcomes included proportion of courses with appropriate dose and dose frequency, and proportion of patients who achieved target concentrations after the first dose adjustment.

RESULTS

In total, 69 patients were included, with 129 vancomycin courses. The median initial vancomycin trough concentration was 12 (range: 4-36) mg/L. The target trough concentration was achieved in 75% of courses after the initial dose with appropriate TDM, and 84% of courses after TDM-guided dose adjustments. Patients were dosed appropriately in 121/129 courses and TDM was performed correctly according to protocol in 51/93 courses. A dose adjustment was performed in 18/29 courses, to increase target attainment.

CONCLUSIONS

This study showed that there is a need for an increase in dose to improve target attainment. There is also a need to explore more effective TDM strategies to increase the proportion of neonatal patients attaining vancomycin target trough concentrations.

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.

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.

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.

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.

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.

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).

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.

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.

A population pharmacokinetic model for individualised dosage regimens of vancomycin in Chinese neonates and young infants

Population pharmacokinetic (PPK) modelling is an easy and impartment method for estimating drug concentration for use inindividualized therapy, especially for young patients and to help protect drug-induced diseases. The purpose of this study was to develop a PPK model for effective dosing of vancomycin in Chinese neonates and young infants. The PPK modelling tool Phoenix^® NLME^™ was use to assess demographic and routine clinical pharmacokinetic (PK) data retrospectively collected for patients admitted to Children's Hospital of Chongqing Medical University between 2011 and 2016. Data of patients admitted to the hospital between January and June of 2017 were used in validation study, and the final model was also preliminary validated in 2 cases in another hospital. A total of 421 serum samples from 316 patients were included in the initial PPK analysis. A two-compartment PPK model was developed, and exponential-error model was used to describe inter-individual variability of clearance. Residual variability was described by an additive model. The final PPK model was demonstrated as valid by internal and external model evaluation. Of note, the clearance and volume of vancomycin in Chinese neonates and young infants may be greater than in Caucasians. Herein, we describe the establishment of an accurate PPK model of vancomycin for Chinese neonates and young infants, which may be useful as a dosing algorithm for this particular paediatric population.

Comparison of intermittent versus continuous vancomycin infusion for the treatment of late-onset sepsis in preterm infants

BACKGROUND

Vancomycin a frequently used antimicrobial for the treatment of late-onset neonatal sepsis. It can be infused either intermittently or continuously, however, there is no consensus on the optimal dosing regimen.

AIM

To evaluate microbiological outcomes, clinical response and adverse events of vancomycin when administered via continuos intravenous infusion.

METHODS

The files of preterm infants (<34 weeks), who received either intermittent (group I, n = 41) or continuous (group II, n = 36) vancomycin infusion for the treatment of late-onset sepsis, were investigated retrospectively. Clinical and demographic features were recorded.

RESULTS

Clinical improvement rates, Töllner scores and microbiological outcomes did not differ significantly between groups. At 48th hour of vancomycin infusion, 52.8% of infants achieved therapeutic concentrations of vancomycin in group II compared with 34.1% of patients in group I (p = 0.002). Thirty-nine percent of infants in group I had supratherapeutic concentrations of vancomycin at 48th hour compared with 5.6% in group II (p = 0.002). Dose adjustment rate in group I did not differ than group II (65.9% vs. 52.8% respectively, p = 0.3). However, when we subdivide group I into two according to dosing intervals, dose adjustment rates were more common in infants with a gestational age <29 weeks for whom intermittent infusion was performed in 18 hours intervals (92.9% vs 51.9% , p = 0.014).

CONCLUSION

In preterm infants, continuous and intermittent infusions of vancomycin have similar clinical efficacies. Continuous infusion is well-tolerated and require less blood sampling compared to intermittent infusion especially in infants less than 29 weeks of gestational age.

Towards Rational Dosing Algorithms for Vancomycin in Neonates and Infants Based on Population Pharmacokinetic Modeling

Because of the recent awareness that vancomycin doses should aim to meet a target area under the concentration-time curve (AUC) instead of trough concentrations, more aggressive dosing regimens are warranted also in the pediatric population. In this study, both neonatal and pediatric pharmacokinetic models for vancomycin were externally evaluated and subsequently used to derive model-based dosing algorithms for neonates, infants, and children. For the external validation, predictions from previously published pharmacokinetic models were compared to new data. Simulations were performed in order to evaluate current dosing regimens and to propose a model-based dosing algorithm. The AUC/MIC over 24 h (AUC24/MIC) was evaluated for all investigated dosing schedules (target of >400), without any concentration exceeding 40 mg/liter. Both the neonatal and pediatric models of vancomycin performed well in the external data sets, resulting in concentrations that were predicted correctly and without bias. For neonates, a dosing algorithm based on body weight at birth and postnatal age is proposed, with daily doses divided over three to four doses. For infants aged <1 year, doses between 32 and 60 mg/kg/day over four doses are proposed, while above 1 year of age, 60 mg/kg/day seems appropriate. As the time to reach steady-state concentrations varies from 155 h in preterm infants to 36 h in children aged >1 year, an initial loading dose is proposed. Based on the externally validated neonatal and pediatric vancomycin models, novel dosing algorithms are proposed for neonates and children aged <1 year. For children aged 1 year and older, the currently advised maintenance dose of 60 mg/kg/day seems appropriate.

How to use vancomycin optimally in neonates: remaining questions

In neonates, vancomycin, a narrow-spectrum antibiotic, is the first choice of treatment of late-onset sepsis predominantly caused by Gram-positive bacteria (coagulase-negative staphylococci and enterococci). Although it has been used for >50 years, prescribing the right dose and dosing regimen remains a challenge in neonatal intensive care units for many reasons including high pharmacokinetic variability, increase in the minimal inhibition concentration against staphylococci, lack of consensus on dosing regimen and way of administration (continuous or intermittent), duration of treatment, use of therapeutic drug monitoring, limited data on short- and long-term toxicity, risk of mutant selection and errors of administration linked to concentrated formulations. This article highlights and discusses future research directions, with specific attention given to dosing optimization of vancomycin, including the advantages of modeling and simulation approaches.

Good practice recommendations for paediatric outpatient parenteral antibiotic therapy (p-OPAT) in the UK: a consensus statement

There is compelling evidence to support the rationale for managing children on intravenous antimicrobial therapy at home whenever possible, including parent and patient satisfaction, psychological well-being, return to school/employment, reductions in healthcare-associated infection and cost savings. As a joint collaboration between the BSAC and the British Paediatric Allergy, Immunity and Infection Group, we have developed good practice recommendations to highlight good clinical practice and governance within paediatric outpatient parenteral antibiotic therapy (p-OPAT) services across the UK. These guidelines provide a practical approach for safely delivering a p-OPAT service in both secondary care and tertiary care settings, in terms of the roles and responsibilities of members of the p-OPAT team, the structure required to deliver the service, identifying patients and pathologies that are suitable for p-OPAT, ensuring appropriate vascular access, antimicrobial choice and delivery and the clinical governance aspects of delivering a p-OPAT service. The process of writing a business case to support the introduction of a p-OPAT service is also addressed.

Neonatal vancomycin continuous infusion: still a confusion?

BACKGROUND

Continuous infusions of vancomycin over 24 hours have been shown in adults to reduce drug toxicity, lower treatment costs and require fewer blood samples for therapeutic drug monitoring. They may also improve clinical outcome through earlier attainment of target drug concentrations. In neonates, there is no consensus on vancomycin dosing. We reviewed the literature to assess the evidence for vancomycin dosing regimens for continuous infusion in neonates.

METHODS

Medline and Embase were searched for studies about continuous vancomycin dosing regimens in neonates that reported serum drug concentrations. The search identified 469 articles, of which 5 were relevant.

RESULTS

Five prospective studies were included; 2 studies used non-linear mixed effects modeling. Vancomycin was administered with parenteral nutrition or 5% dextrose. Target serum concentrations varied (range: 10-30 mg/L). Four studies used loading doses before continuous infusion; only 1 documented achievement of therapeutic concentrations after the load. The time to a therapeutic concentration was not reported for the other studies. Attainment of target concentrations ranged from 56% to 89% of measurements. Only 1 study compared intermittent to continuous infusions, reporting higher attainment of target concentrations with continuous dosing (82% vs. 46%). No adverse effects were reported, although 3 neonates developed a reversible raised serum creatinine in the setting of septicemia.

CONCLUSION

Continuous infusions of vancomycin in neonates are well tolerated, require less blood sampling and may result in improved attainment of target concentrations. Further prospective studies are needed in this population.

Vancomycin dosing in children: what is the question?

Vancomycin has been in clinical use for over 60 years, but it is still not clear what dose should be given to children. Effective treatment with vancomycin requires a serum concentration well above the minimum inhibitory concentration (MIC) of the bacteria being treated. This is predicted by the area under the concentration curve (AUC) divided by the MIC being >400 (AUC/MIC). Recent concerns about increasing MIC in staphylococci have lead to recommendations to aim for higher trough vancomycin levels (15-20 mg/L). In current practice, most children do not achieve these trough levels. Modelling and pharmacokinetic studies in children suggest these trough levels may not be necessary if the MIC of the organisms is 1 mg/L or less. Further, large-scale studies are needed to determine the most appropriate dosing of vancomycin in children. While awaiting these, it is time to consider moving to 15 mg/kg 6 h as a standard starting regime for vancomycin. It is also vital to determine the MIC of the organism being treated, as this may give some guidance about suitable trough levels to be aimed for. There is currently little evidence to guide the use of loading doses or continuous vancomycin infusions in children.