Impact of a hospitalwide increase in empiric pediatric vancomycin dosing on initial trough concentrations

Practical approaches to improve vancomycin-related patient outcomes in pediatrics- an alternative strategy when AUC/MIC is not feasible

BACKGROUND

Anecdotal experience and studies have shown that most pediatric patients fail to reach target therapeutic vancomycin trough levels (VTLs) and required higher total daily doses (TDD). This retrospective study aims to evaluate the frequency of hospitalized children who achieved target VTLs with a vancomycin (VNCO) dosing regimen of 40-60 mg/kg/d q6h and to assess the VNCO-TDD required to attain the target and their effects on clinical outcomes in pediatric patients.

METHODS

After ethical approval, patients of 3 month-12 years were evaluated in this chart review study who received ≥ 3 intravenous-VNCO doses and appropriately drawn blood samples of VTLs between October 2019 to June 2020. Data were retrieved for demographic and clinical characteristics, culture reports, VNCO-regimen, subsequent steady-state VTLs, concomitant nephrotoxic medications, and serum creatinine. Clinical pharmacists made interventions in VNCO therapy and higher VNCO-TDD were used. Safety of higher vs standard daily doses and their clinical impact on duration of therapy, hospital stay, and survival were evaluated.

RESULTS

A total of 89 (39.1%) patients achieved target VTLs (SD-group). The smallest proportion (18.2%) of 2-6 years patients achieved target VTLs and reported the lowest mean value of 10.1 ± 0.2 mg/L which was a significant difference (p < 0.05) from all subgroups. Subtherapeutic VTLs were observed in 139 (60.9%) cases (HD-group), who received higher VNCO-TDD of 72 ± 8.9 mg/kg/d q6h to achieve the targets. Duration of therapy in culture-proven septic patients was significantly (p = 0.025) longer in SD-group [18.4 ± 12.2 days] than HD-group [15.1 ± 8.9 days]. Nephrotoxicity and electrolyte imbalance were comparable in groups. Length of hospital stay was significantly (p = 0.011) longer [median 22 (range 8-55) days] in SD-group compared to HD-group [median 16 (range 8-37) days]. Number of patients survived in HD-group were significantly (p = 0.008) higher than SD-group [129 (92.8%) vs 75 (84.3%)].

CONCLUSION

Initial Vancomycin doses of 72 ± 8.9 mg/kg/day q6h are required to achieve therapeutic target in 3 months to 12 years patients. High doses are not associated with higher nephrotoxicity than reported with low doses. In addition, efficient pharmacist intervention for the use of higher VNCO-TDD may improve clinical outcomes in terms of duration of therapy, hospital stay, and survival.

Implementation of a Pharmacist-Driven Vancomycin and Aminoglycoside Dosing Service in a Pediatric Hospital

OBJECTIVE

Pharmacy-driven antibiotic dosing services have been shown to improve clinical outcomes in adult patients. This study evaluated the effect of a pharmacist-driven antimicrobial dosing service on the percentage of therapeutic serum concentrations achieved following initial vancomycin or aminoglycoside dosing regimens. A secondary objective was to determine the effect of the dosing service on nephrotoxicity in pediatric patients.

METHODS

This single-center, retrospective study used data obtained from an electronic medical record to evaluate the utility of a pharmacist-driven vancomycin or aminoglycoside dosing protocol. Assessments of target, subtherapeutic, and supratherapeutic serum concentrations were evaluated. The occurrence of changes in serum creatinine and presentation of acute kidney injury (AKI) were also determined.

RESULTS

The incidence (n [%]) of a therapeutic initial serum concentration was not statistically significant between pre-protocol and post-protocol groups (21 [46.7%] vs 22 [48.9%], respectively; p = 0.834). The incidence of initial supratherapeutic concentrations (19 [42.2%] vs 7 [15.6%]; p = 0.005) and the average number of supratherapeutic concentrations per antibiotic course (0.76 vs 0.26; p = 0.01) were higher in the pre-protocol group compared with the post-protocol group. The incidence of AKI was significantly lower in the post-protocol group (2.2% vs 13.3%; p = 0.049).

CONCLUSIONS

Implementation of a pharmacist-driven dosing service did not affect the likelihood of achieving an initial therapeutic concentration. However, it did reduce the likelihood of both supratherapeutic concentrations and AKI. Additional studies in pediatric patients are needed to affirm the use of pharmacist dosing services.

Association of Initial Trough Concentrations of Vancomycin with Outcomes in Pediatric Patients with Gram-Positive Bacterial Infection

Vancomycin is a glycopeptide antibiotic used for the treatment of Gram-positive infections. For adult patients, treatment with vancomycin requires effective therapeutic drug-monitoring (TDM) to achieve clinical outcomes and reduce the incidence of adverse effects. However, it remains still unclear whether the TDM with vancomycin is beneficial in yielding better clinical outcomes in pediatrics. The objective of our study was to evaluate whether the clinical response to treatment was associated with initial trough concentrations of vancomycin in pediatric patients. A retrospective observation study of 60 patients (age: 1 month-15 years) who had completed and qualified for analysis was conducted at Kyoto University Hospital. The response to treatment was assessed by the time to resolution of fever and time to 50% decline in C-reactive protein (CRP). In addition, we explored whether vancomycin trough level was associated with the baseline characteristics. Trend analysis showed that there were significant correlations between vancomycin trough level and age, body weight, estimated glomerular filtration rate, and serum albumin levels. The time to resolution of fever of the patients with higher initial trough level (≥ 5 µg/mL) was significantly lower than that of the patients with lower trough level (< 5 µg/mL). The higher vancomycin concentration tended to be associated with the shorter time to 50% decline in CRP. The findings suggest that initial trough concentration is important in achieving better outcomes with vancomycin treatment in pediatrics.

Pediatric Antibiotic Stewardship: Optimization of Vancomycin Therapy Based on Individual Pharmacokinetics

BACKGROUND

Vancomycin has been a first-line treatment for Gram-positive infections for decades. However, strategies for therapeutic drug monitoring (TDM) and dose-optimization in pediatrics remain controversial. In this study, we analyzed the impact of specific antibiotic stewardship interventions on efficacy and safety of vancomycin therapy.

METHODS

From September 2014 to May 2017, we conducted a prospective study to compare a control and a TDM intervention group in our tertiary care center. As part of an antibiotic stewardship program, we implemented internal guidelines on correct vancomycin dosing, TDM timing, as well as targeted trough level range and installed a pharmacokinetic (PK) consultation service to adapt vancomycin dosing to individually calculated PK parameters. As primary clinical outcomes, the percentage of patients with sustained therapeutic vancomycin trough levels and treatment days with therapeutic vancomycin trough levels, that is, 10-15 mg/L were analyzed. Secondary outcomes included nephrotoxicity, readmission rate and mortality. Median daily dose required to achieve therapeutic trough levels was examined.

RESULTS

Clinical outcomes for 90 control patients were compared with outcomes for 19 patients guided by a PK consultation service. Percentage of patients with sustained therapeutic vancomycin trough levels increased from 17.8% to 94.7% (P < 0.001) and percentage of treatment days with therapeutic vancomycin trough levels increased from 18.4% (117/637) to 665% (155/233, P < 0.001). Readmission rate decreased from 24.4% to 5.3% (P = 0.07). No differences in nephrotoxicity or mortality rate were observed between groups. A median daily dose of 72 mg/kg/d was required to achieve therapeutic trough levels.

CONCLUSIONS

Our data demonstrate that implementation of internal guidelines and a PK consultation service was associated with a profound improvement of vancomycin therapy and, therefore, patient safety.

Intravenous Vancomycin Therapeutic Drug Monitoring in Children: Evaluation of a Pharmacy-Driven Protocol and Collaborative Practice Agreement

BACKGROUND

Vancomycin optimization is challenging, requiring careful therapeutic drug monitoring (TDM) to avoid toxicity and ensure an efficacious concentration. Most prescriptions are empiric and often discontinued within 72 hours, which makes early TDM unnecessary. Although TDM using trough levels is common, the area under the concentration-time curve (AUC) is the preferred pharmacodynamic target. We studied the effect of a pharmacy-driven vancomycin collaborative practice agreement (CPA) at a children's hospital that delayed TDM up to 72 hours and targeted a 2-point 24-hour AUC of ≥400 mg × h/L.

METHODS

We retrospectively reviewed vancomycin courses in patients aged ≥30 days who received vancomycin between April 1, 2011, and August 30, 2017. We implemented the CPA on June 1, 2014. Outcomes included CPA use, use of TDM, dosage adjustments, and development of acute kidney injury; we compared courses given while monitoring only trough levels (TO-TDM) with those given while using the CPA (AUC-TDM). We performed interrupted time series analyses to account for preintervention trends.

RESULTS

We included 2379 courses in the TO-TDM period and 2155 in the AUC-TDM period. During AUC-TDM, 87% of the courses were managed by the CPA. In adjusted interrupted time series analyses, CPA implementation was associated with an initial change in level of -0.265 (95% confidence interval [CI], -0.336 to -0.189) TDM and an initial change in level of -0.332 (95% CI, -0.506 to -0.163) dosage adjustments. The 1-year risk of acute kidney injury decreased after CPA implementation (odds ratio, 0.695 [95% CI, 0.539-0.91]).

CONCLUSION

The pharmacy-driven vancomycin CPA resulted in less monitoring and fewer dose adjustments without increasing AKI.

Steady-state Pharmacokinetics of Vancomycin in Children Admitted to Pediatric Intensive Care Unit of a Tertiary Referral Center

Aims and objectives

Vancomycin is a drug of choice for various gram-positive bacterial (GPB) infections and is largely prescribed to pediatric intensive care unit (PICU) patients. Despite the different pathophysiology of these patients, limited data are available on pharmacokinetics of vancomycin. There are lack of data for critically ill Indian children; hence, study was conducted to assess the steady-state pharmacokinetics in children admitted to PICU.

Materials and methods

Twelve subjects (seven males, five females) aged 1–12 years were enrolled. Vancomycin (dose of 20 mg/kg per 8 hours) was infused for over 1 hour and steady-state pharmacokinetics was performed on day 3. Vancomycin concentrations were measured by the validated liquid chromatography mass spectrometry method. Pharmacokinetic parameters were calculated using Winnonlin (Version 6.3; Pharsight, St. Louis, MO).

Results

The steady-state mean C_ssmax was 40.94 μg/mL (±15.07), and mean AUC_{0–8 hours} was 124.15 μg/mL (±51.27). The mean t_1/2 was 4.82 hours (±2.71), Vd was 12.48 L (±4.43), and Cl was 2.08 mL/minute (±0.89). The mean AUC_0–24 among 12 subjects was 372.44 μg/mL (±153.82). Among 35 measured trough concentrations, 23 (65.71%) were below, 11 (31.43%) were within, and 1 (2.86%) was above the recommended range.

Conclusion

The pharmacokinetic parameters of vancomycin were comparable with previously reported studies. However, recommended trough levels (10–20 μg/mL) were not achievable with current recommended dosing of 60 mg/kg/day.

How to cite this article

Mali NB, Tullu MS, Wandalkar PP, Deshpande SP, Ingale VC, Deshmukh CT, et al. Steady-state Pharmacokinetics of Vancomycin in Children Admitted to Pediatric Intensive Care Unit of a Tertiary Referral Center. IJCCM 2019;23(11):497–502.

Desired vancomycin trough concentration to achieve an AUC0-24 /MIC ≥400 in Chinese children with complicated infectious diseases

A vancomycin steady-state trough concentration (C_min ) of 15-20 mg/L is recommended for achieving a ratio of the 24-hour area under the curve to the minimum inhibitory concentration (AUC_0-24 /MIC) of ≥400 in adults. Since few paediatric data are available, our objectives were to (a) measure the pharmacokinetic indices of vancomycin and (b) determine the correlation between C_min and AUC_0-24 /MIC in paediatric patients. Population-based pharmacokinetic modelling was performed for paediatric patients to estimate the individual parameters. The relationship between C_min and the calculated AUC_0-24 /MIC was explored using linear regression and a probabilistic framework. A sensitivity analysis was also conducted using Monte Carlo simulations. Body-weight significantly influenced the pharmacokinetics of vancomycin. Based on real data and simulations, C_min ranges of 5.0-5.9 and 9.0-12.9 mg/L were associated with AUC_0-24 /MIC ≥400 for MIC values of ≤0.5 and ≤1 mg/L, respectively. Vancomycin regimens of 10 and 15 mg/kg every 6 hours achieved a C_min of 5.0-5.9 mg/L and AUC_0-24 /MIC ≥400 in >90% of the children when MIC was ≤0.5 mg/L. At a MIC of ≤1 mg/L, vancomycin at 15 mg/kg every 6 hours achieved C_min of 9.0-12.9 mg/L and AUC_0-24 /MIC ≥400 in 2.0- and 1.6-fold as many children compared to a dose of 10 mg/kg every 6 hours, respectively. Vancomycin C_min values of 5.0-12.9 mg/L were strongly predictive of achieving AUC_0-24 /MIC ≥400, and rational dosing regimens of 10-15 mg/kg q6h were required in paediatric patients, depending on the pathogen.

Vancomycin Treatment Failure in Children With Methicillin-Resistant Staphylococcus aureus Bacteremia

OBJECTIVES

Limited data exist regarding clinical outcomes of invasive methicillin-resistant Staphylococcus aureus (MRSA) infections in children treated with vancomycin. Treatment success in adults correlates best with an area under the curve/minimum inhibitory concentration (AUC₂₄/MIC) ratio ≥400. It is unknown if this relationship is useful in children.

METHODS

Charts of children who received vancomycin ≥5 days for MRSA bacteremia with a steady state trough were reviewed. AUC₂₄/MIC ratios were estimated using 2 different vancomycin clearance equations. Vancomycin treatment failure was defined as persistent bacteremia ≥7 days, recurrent bacteremia within 30 days, or 30-day mortality.

RESULTS

There were 67 bacteremia episodes in 65 patients. Nine (13.4%) met failure criteria: persistent bacteremia (n = 6), recurrent bacteremia (n = 2), 30-day mortality (n = 1). There were no differences between patients receiving <60 mg/kg/day and ≥60 mg/kg/day of vancomycin in median trough (11.9 versus 12.3 mg/L, p = 0.1). Troughs did not correlate well with AUC₂₄/MIC ratios (R ² = 0.32 and 0.22). Patients receiving ≥60 mg/kg/day had greater probability of achieving ratios ≥400. There were no significant differences in median dose (p = 0.8), trough (p = 0.24), or AUC₂₄/MIC ratios (p = 0.07 and p = 0.6) between patients with treatment success and failure.

CONCLUSIONS

Treatment failure was lower than previously reported in children. AUC₂₄/MIC ratios ≥400 were frequently achieved but were not associated with treatment success, dose, or troughs. Prospective studies using standard definitions of vancomycin treatment failure are needed to understand treatment failure in children with MRSA bacteremia.

Incidence and Risk Factors for Vancomycin Nephrotoxicity in Acutely Ill Pediatric Patients

Background: Particularly with the current increased vancomycin dosing trends, the true risk of the agent's nephrotoxicity is not well characterized and remains of concern. Objective: To determine the incidence of vancomycin nephrotoxicity in acutely ill hospitalized children and to secondarily characterize the risk factors for this complication. Methods: A single-center retrospective cohort study conducted at UCSF Benioff Children's Hospital from June 2012 to June 2015. Inpatients 3 months to <19 years who received intravenous vancomycin for ≥48 hours were included. The primary outcome was incidence of nephrotoxicity, defined as an increase in serum creatinine by ≥50% from baseline. Univariate and multivariate analyses were conducted to identify risk factors for vancomycin nephrotoxicity. Results: A total of 291 patients (272 nonnephrotoxic and 19 nephrotoxic) were included in the analysis. Of the 19 patients, 12 (4.1%) were found to have moderate to severe toxicity. The median duration of therapy was 3 (3-5) and 4 (3-6) days for the group with "no nephrotoxicity" and "nephrotoxicity," respectively. The mean time for the serum creatinine to return to normal in patients with nephrotoxicity was 5.1 days. In the multivariate analysis, only final trough concentration ≥15mg/dL (odds ratio = 3.49, 95% confidence interval = 1.2-10.1; P = .021) and receipt of piperacillin/tazobactam (odds ratio = 3.14, 95% confidence interval = 1.02-9.6; P = .046) were significantly associated with nephrotoxicity. Conclusion: The rate of moderate to severe vancomycin-associated nephrotoxicity in acutely ill children is relatively uncommon and reversible. Kidney injury is associated with increased vancomycin trough concentrations and concomitant receipt of nephrotoxins, particularly piperacillin/tazobactam.

Vancomycin use, dosing and serum trough concentrations in the pediatric population: a retrospective institutional review

BACKGROUND

Vancomycin is used primarily for Gram-positive infections. Recommended dosage regimens and targeted therapeutic levels vary between institutions.

OBJECTIVES

This study aims to describe therapeutic levels according to initial vancomycin doses and patient's age. A secondary objective was to evaluate appropriateness of vancomycin use in our hospital.

METHODS

A retrospective chart review was conducted at the Children's Hospital of Eastern Ontario. Patients included in this study were classified by age (neonates, infants, children and adolescents) and categorized into those who received vancomycin ≤5 and >5 days. Initial vancomycin dosing regimens and corresponding initial trough levels obtained were evaluated. Initial trough levels drawn in relation to the third, fourth, or fifth doses corresponding to the first course of therapy were analyzed. Acceptable trough levels ranged from 5-20 mg/L.

RESULTS

One-hundred-and-sixty-four patients who received intravenous vancomycin in 2013 were included. Of the 229 courses of vancomycin, 190 (83%) were used 5 days or less (mean 4.9 days). Sixteen infants (88.9%) and 21 adolescents (100%), who received vancomycin empiric dosing of 60 mg/kg/day, had initial trough levels >5mg/L. However, in the children's group 20 (37.7%) did not reach levels >5 mg/L. None of vancomycin minimum inhibitory concentration (MIC) values were >1mg/L for the four patients who had infections due to methicillin-resistant Staphylococcus aureus strains.

CONCLUSIONS

In our institution, initial empiric vancomycin dosing of 60 mg/kg/day resulted in levels ≥5mg/L in most infants and adolescents. It remains unclear why some children aged 1-12 years did not achieve these levels.

Risk Factors for Non-Therapeutic Initial Steady-State Vancomycin Trough Concentrations in Children and Adolescents Receiving High Empiric Doses of Intravenous Vancomycin

BACKGROUND

Achieving vancomycin troughs of 15-20 μg/mL remains challenging in children. Our objective was to identify risk factors associated with non-therapeutic initial vancomycin troughs in children.

METHODS

We conducted a retrospective cohort study of children who received intravenous vancomycin with at least one initial steady-state trough obtained. Patients who achieved therapeutic troughs (15-20 μg/mL in the 20-mg/kg/dose sub-cohort and 10-15 μg/mL in the 15-mg/kg/dose sub-cohort) were compared with those with subtherapeutic troughs (<15 and <10 μg/mL, respectively) and supratherapeutic troughs (>20 and >15 μg/mL, respectively) separately to determine risk factors associated with non-therapeutic troughs.

RESULTS

A total of 153 vancomycin courses in 140 patients met study eligibility criteria. Of 45 patients who received 20 mg/kg/dose of empiric vancomycin, 60, 16, and 24% were subtherapeutic, therapeutic, and supratherapeutic, respectively. Each 10-mL/min/1.73 m² increase in initial creatinine clearance (CrCl) was associated with a 47% increase in the odds of an initial subtherapeutic trough (adjusted odds ratio [aOR] 1.47; 95% CI 0.98-2.22). Of 108 patients who received 15 mg/kg/dose of empiric vancomycin, 62, 19, and 19% were subtherapeutic, therapeutic, and supratherapeutic, respectively. Each 10-mL/min/1.73 m² increase in initial CrCl was associated with an 18% increase in the odds of an initial subtherapeutic trough (aOR 1.18; 95% CI 1.02-1.37).

CONCLUSION

Achieving vancomycin troughs of 15-20 μg/mL for severe Gram-positive infections continues to be challenging in children, even at higher empiric doses of 20 mg/kg/dose IV every 6-8 h. Children with higher initial CrCls are particularly susceptible to subtherapeutic initial steady-state vancomycin troughs.

Validation of a pediatric population pharmacokinetic model for vancomycin

BACKGROUND

Vancomycin is often required to treat serious infections in children, including methicillin-resistant Staphylococcus aureus infections. The pharmacodynamic index that best predicts efficacy with vancomycin use for methicillin-resistant S. aureus infection in adults is the 24-hour area under the curve (AUC) over the minimum inhibitory concentration. Although multiple pediatric population pharmacokinetic (PK) vancomycin models have been published, few use Bayesian optimization. The current standard of care remains measuring vancomycin serum trough concentrations as a surrogate marker of AUC.

MATERIALS AND METHODS

A prospective validation of a pediatric population PK model of vancomycin was performed. Hospitalized children younger than 18 years receiving vancomycin at Cincinnati Children's Hospital Medical Center were invited to participate. Peak, trough, and random vancomycin serum concentrations were used for Bayesian estimation of individual PK parameters. Model covariates included age, weight, and serum creatinine. To evaluate the predictive performance of the model, precision and bias were measured and compared using the 95% confidence interval.

RESULTS

Fifteen subjects were enrolled; 13 subjects had vancomycin serum concentrations drawn per protocol. Of those 13 subjects, the median age was 6 years and 54% were male. Significant medical conditions included cancer (54%), lung disease (23%), neurologic disorders (23%), and prior transplantation (15%). The initial serum creatinine was normal (median, 0.33; interquartile range, 0.23-0.4 mg/dL), and none had underlying renal dysfunction. Equivalence of bias and precision between the original model validation and the Cincinnati Children's Hospital Medical Center validation were found.

CONCLUSIONS

Pediatric population PK models for vancomycin with Bayesian estimation can be used to reliably predict vancomycin exposure in children. Using AUC instead of trough serum concentrations alone can provide an opportunity to maximally optimize vancomycin administration in children.

A Prospective Study to Assess Vancomycin Serum Concentrations inPediatric Patients with Current Dosing Guidelines

Concerns about increasing bacterial resistance to vancomycin, have caused the adult treatment guidelines to recommend higher trough concentrations based on the type and location of infectious disease. Although these recommendations are not specific to children, the values can be extrapolated. This prospective study was designed to evaluate efficacy of current vancomycin dosing recommendations to achieve therapeutic trough serum concentration in pediatric patients. Laboratory data, vancomycin dosing and subsequent serum concentrations of children in a community teaching pediatrics hospital were collected and analyzed. Trough serum levels were determined at steady state and compared with Infectious Disease Society of America (IDSA) 2011 guidelines for the treatment of Methicillin-Resistant Staphylococcus Aureus (MRSA) infections. In a prospective observational, cross-sectional study in a university medical center in Tehran, Iran, 50 patients, who received vancomycin for more than 4 doses, were recruited and their trough vancomycin level was determined. The mean age and creatinine clearance of patients were 5.47 ± 4.24 and 87.5 ± 31.25, respectively. Eleven (22%) patients received vancomycin at 40 mg/kg/day (low dose) and 39 (78%) at 60 mg/kg/day (high dose). Considering trough goals of 10-14 and 15-20 mg/L in low and high dose groups, serum levels in 91% (73% sub- therapeutics) and 85% (69% sub-therapeutics) of patients were not in recommended therapeutic range, respectively. This study has shown that current recommended vancomycin dosing regimens in pediatric patients (40-60 mg/kg/day), resulted in sub-therapeutic serum concentrations in our study population.

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.

Evaluation of Target Attainment of Vancomycin Area Under the Curve in Children With Methicillin-Resistant Staphylococcus Aureus Bacteremia

BACKGROUND

Vancomycin is often required to treat methicillin-resistant Staphylococcus aureus bacteremia in children. Treatment failure occurs in up to 50% of adults and is associated with a 24-hour area under the curve/minimum inhibitory concentration (AUC24h/MIC) <400. We sought to identify patient factors associated with vancomycin AUC and whether AUC24h/MIC <400 was predictive of treatment failure in children.

METHODS

Hospitalized children younger than 18 years with methicillin-resistant Staphylococcus aureus bacteremia receiving vancomycin were included in a retrospective cohort study. AUC24h was calculated using a validated pharmacokinetic model. Factors such as age, sex, underlying conditions, presence of foreign bodies, patient site of infection, and markers of illness severity were examined for an association with vancomycin AUC, and AUC24h/MIC was evaluated for an association with treatment failure.

RESULTS

Subjects requiring intensive care unit support were significantly more likely to have higher vancomycin AUC24h and AUCavg than those subjects not needing intensive care unit support. Although vancomycin serum trough concentrations are predictive of vancomycin AUC, suboptimal exposure of vancomycin occurred in almost 20% of subjects despite trough concentrations within the target range. A relationship between vancomycin AUC24h/MIC and treatment failure could not be established.

CONCLUSIONS

To ensure optimal AUC/MIC pharmacodynamic index, especially in critically ill patients, estimation of the AUC is critical.

Vancomycin dosing and target attainment in children

BACKGROUND/PURPOSE

The aim of this study is to determine the best dosing strategy for vancomycin by studying the associated factors and examining correlations between the area under the plasma concentration-time curve (AUC) values and trough concentrations in children.

METHODS

Children aged 3 months to 18 years were included if they received vancomycin for more than three doses between January 1, 2010 and December 31, 2012 and had one or more serum vancomycin trough concentrations. Vancomycin clearance (CL) was calculated using the following model: CL = 0.248*Wt^0.75*(0.48/serum creatinine)^0.361*[ln (age)/7.8]^0.995. The AUC (mg-h/L) was calculated by 24-hour dose (mg/kg/d)/CL(L/h). The value of AUC divided by the minimum inhibitory concentration (MIC) of vancomycin was AUC/MIC.

RESULTS

A total of 218 children were included. The mean age was 6.0 ± 5.1 years and the mean body weight was 20 ± 11.7 kg. Vancomycin trough concentrations were moderately correlated with AUC values (r² = 0.232, p < 0.01). Dosing of 15 mg/kg/dose q6h produced significantly higher AUC values (p < 0.001) and vancomycin trough concentrations (p < 0.001) compared to dosing of 10 mg/kg/dose q6h. In children receiving a 10-mg/kg/dose q6h, 5.6% (5/90) achieved the target trough concentrations of 15-20 μg/mL and 9.5% (5/90) achieved the goal AUC/MIC ≥ 400. In children receiving a 15-mg/kg/dose q6h, 13% (6/46) achieved the target trough concentrations of 15-20 μg/mL, whereas 54.3% (25/46) achieved the goal AUC/MIC ≥ 400.

CONCLUSION

A 15-mg/kg/dose q6h compared to a 10-mg/kg/dose q6h is more likely to achieve target trough concentrations of 15-20 μg/mL and the goal AUC/MIC ≥ 400.

Late-Occurring Vancomycin-Associated Acute Kidney Injury in Children Receiving Prolonged Therapy

Background: Acute kidney injury (AKI) in patients receiving vancomycin has been associated with trough concentrations ≥15 mg/L and longer therapy duration. The objective of this study was to determine the incidence and factors associated with late AKI in children receiving ≥8 days of vancomycin therapy. Methods: Children aged 30 days to 17 years who were admitted to our institution and received intravenous vancomycin for at least 8 days during January to December of 2007 and 2010 and had a suspected or proven gram-positive infection were included. Late AKI was categorized as AKI occurring after the first 7 days of therapy and within 48 hours following vancomycin discontinuation. The primary outcome was incidence of late AKI as determined by modified pRIFLE criteria. Results: One-hundred sixty-seven patients were included, with a median (interquartile range) age (years) and weight (kg) of 2 (1-7) and 12.5 (8.9-23.8). Late AKI was identified in 12.6% (21/167). A higher percentage of late AKI patients received concomitant treatment with intravenous acyclovir, amphotericin products, or piperacillin-tazobactam. Age <1 year was the only factor independently associated with late AKI development (odds ratio = 4.4; 95% confidence interval = 1.3-15.4). Conclusions: Late AKI occurred in nearly 13% of children receiving ≥8 days of vancomycin therapy. This study suggests that vancomycin trough concentrations are not associated with late AKI, but that age <1 year and concomitant administration of certain nephrotoxins may be factors associated with increased risk.

Vancomycin pharmacokinetic models: informing the clinical management of drug-resistant bacterial infections

This review aims to critically evaluate the pharmacokinetic literature describing the use of vancomycin in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. Guidelines recommend that trough concentrations be used to guide vancomycin dosing for the treatment of MRSA infections; however, numerous in vitro, animal model and clinical studies have demonstrated that the therapeutic effectiveness of vancomycin is best described by the area under the concentration versus time curve (AUC) divided by the minimum inhibitory concentration (MIC) of the infecting organism (AUC/MIC). Among patients with lower respiratory tract infections, an AUC/MIC ≥400 was associated with a superior clinical and bacteriological response. Similarly, patients with MRSA bacteremia who achieved an Etest AUC/MIC ≥320 within 48 h were 50% less likely to experience treatment failure. For other patient populations and different clinical syndromes (e.g., children, the elderly, patients with osteomyelitis, etc.), pharmacokinetic/pharmacodynamic studies and prospective clinical trials are needed to establish appropriate therapeutic targets.

Balancing vancomycin efficacy and nephrotoxicity: should we be aiming for trough or AUC/MIC?

Sixty years later, the question that still remains is how to appropriately utilize vancomycin in the pediatric population. The Infectious Diseases Society of America published guidelines in 2011 that provide guidance for dosing and monitoring of vancomycin in adults and pediatrics. However, goal vancomycin trough concentrations of 15-20 μg/mL for invasive infections caused by methicillin-resistant Staphylococcus aureus were based primarily on adult pharmacokinetic and pharmacodynamic data that achieved an area under the curve to minimum inhibitory concentration ratio (AUC/MIC) of ≥400. Recent pediatric literature shows that vancomycin trough concentrations needed to achieve the target AUC/MIC are different than the adult goal troughs cited in the guidelines. This paper addresses several thoughts, including the role of vancomycin AUC/MIC in dosing strategies and safety monitoring, consistency in laboratory reporting, and future directions for calculating AUC/MIC in pediatrics.

Achieving therapeutic vancomycin levels in pediatric patients

BACKGROUND

Vancomycin is widely used to treat infections caused by methicillin-resistant Staphylococcus aureus. Data for dosing and monitoring of this drug in pediatric patients are lacking, and clinicians who are treating children often follow guidelines established for adults.

OBJECTIVES

To examine the total daily doses of vancomycin required to reach therapeutic trough levels (i.e., 10-20 mg/L) in infants, children, and adolescents, and to assess the number of pediatric patients in whom therapeutic trough levels are achieved with current empiric doses (40-60 mg/kg daily).

METHODS

This chart review evaluated patients 1 month to 18 years of age for whom vancomycin was prescribed at a single institution between November 2011 and October 2012. Patients' demographic characteristics, vancomycin dosing parameters, and subsequent steady-state trough concentrations were analyzed.

RESULTS

Overall, the proportion of patients who reached therapeutic trough levels with current empiric doses was 39% (74 of 188). The mean total daily dose (± standard deviation) required to achieve therapeutic trough levels was 57.8 ± 11.5 mg/kg for patients 1 to 5 months of age, 68.9 ± 15.4 mg/kg for those 6 to 23 months of age, 65.8 ± 13.0 mg/kg for those 2 to 12 years of age, and 55.7 ± 11.8 mg/kg for those 13 to 18 years of age.

CONCLUSIONS

Common empiric vancomycin dosing regimens (40-60 mg/kg daily) are not high enough to achieve trough levels of 10-20 mg/L in the majority of pediatric patients. Given these data, the authors suggest a starting dose of 60 mg/kg daily for patients 1 to 5 months of age and those 13 to 18 years of age and a starting dose of 70 mg/kg daily for patients 6 months to 12 years of age.

Pediatric vancomycin dosing: Trends over time and the impact of therapeutic drug monitoring

Monitoring of vancomycin trough concentrations is recommended for pediatric patients in the product label and by several professional societies. However, among a network of freestanding children's hospitals vancomycin therapeutic drug monitoring (TDM) practices were reported to be highly variable. In this study, we sought to evaluate whether trends in vancomycin use and TDM changed across a large healthcare delivery system in Utah and Idaho from 2006 to 2012. Children ≤18 years who received ≥2 vancomycin doses were included. Overall, vancomycin TDM was performed during 5,035 (80%) of 6,259 hospital encounters, in which 85,442 doses were administered and 7,935 concentrations were obtained. Across this time period, the median trough concentration increased from 10.9 to 13.7 µg/mL (P < .001), which temporally coincided with recommendations published by the Infectious Disease Society of America that recommend targeting higher trough concentrations. Two or more abnormally low trough concentrations were accompanied by an increase in the dose 75% of the time. Similarly, ≥2 abnormally high trough concentrations were followed by a decrease in the dose 35% of the time. In aggregate, these data suggest that vancomycin TDM is commonly performed among children and the majority of abnormal trough concentrations were associated with an appropriate modification to the dosing regimen.

Evaluation of vancomycin dosing and corresponding drug concentrations in pediatric patients

OBJECTIVE

To describe the relationships between dosing strategy, age, and vancomycin trough concentrations in pediatric patients.

METHODS

This is a retrospective review of hospitalized pediatric patients between 2 months and 17 years of age treated with intravenous vancomycin from 2008 to 2011. The primary outcome was the number of patients achieving a target trough concentration of 10 to 20 μg/mL in each age group and dosing group. The secondary outcomes were the number of patients in each group to achieve a trough concentration of 15 to 20 μg/mL and the incidence of vancomycin-induced nephrotoxicity.

RESULTS

A total of 102 patients were included in the analysis. Forty-six of 159 evaluated troughs (28.9%) were within the target range of 10 to 20 μg/mL. Dose was found to have a statistically significant effect on the ability to achieve a trough within the target range (P = .01). Of the 159 trough concentrations evaluated, only 11 (6.9%) were within the range of 15 to 20 μg/mL. Nephrotoxicity occurred in 7 patients and was not associated with supratherapeutic trough concentration or dose.

CONCLUSIONS

The number of trough concentrations within the target range of 10 to 20 μg/mL was low, and younger patients often needed doses >60 mg/kg per day to achieve a trough concentration in this range. The dose of vancomycin was found to have a statistically significant effect on the ability to achieve a trough concentration within the target range.

Assessment of initial vancomycin dosing in neonates

BACKGROUND

Vancomycin is recommended for optimal treatment of late-onset sepsis caused by coagulase-negative Staphylococcus in neonates.

OBJECTIVES

To assess the performance of an empirical vancomycin dosing regimen in achieving target trough levels, and to revise this regimen if needed.

METHODS

Data regarding doses and levels were collected and pharmacokinetic parameters were calculated, where possible, for neonates receiving vancomcyin in a neonatal intensive care unit. The primary measure was the percentage of neonates with initial prevancomycin levels of <10 mg/L, 10 mg/L to 20 mg/L and >20 mg/L. Secondary measures included the percentage of neonates with extrapolated trough levels in these ranges, total daily doses that achieved target levels (10 mg/L to 20 mg/L) and total daily doses/dosing intervals that were pharmacokinetically predicted to achieve trough levels of 15 mg/L.

RESULTS

Of 153 infants started on the empirical regimen (15 mg/kg/day to 45 mg/kg/day, depending on postnatal age and weight), 34.2% initially achieved target trough levels (mean 8.7 mg/L). Analysis of actual doses and pharmacokinetically predicted doses required to reach target levels suggested increasing the empirical dosing for all neonatal age groups. The revised regimen used in the present study (20 mg/kg/day to 40 mg/kg/day, depending on postmenstrual age and postnatal age) was predicted to result in 72% of infants achieving initial target trough levels (mean 15.4 mg/L).

CONCLUSIONS

A revised empirical vancomycin dosage regimen for neonates was required based on poor achievement of target trough levels (10 mg/L to 20 mg/L) using the previous regimen. The modified regimen is predicted to reach target trough levels more often and increase the mean initial trough levels achieved. This regimen requires clinical validation in an independent cohort in the future.

Factors Associated With Acute Kidney Injury in Children Receiving Vancomycin

Background: As higher vancomycin doses have been used in children, concern for acute kidney injury (AKI) has increased. Data describing factors associated with AKI, particularly dose-related factors, are limited. Objective: To determine the incidence of AKI in children receiving intravenous vancomycin and to identify factors associated with increased odds of AKI. Methods: A retrospective review of patients admitted to a tertiary academic pediatric hospital from February 2009 to September 2010 was performed. Patients 3 months to <19 years old with normal kidney function, receiving vancomycin for at least 48 hours were included. Incidence of AKI was assessed as defined by the Pediatric-Modified RIFLE criteria. Patients with and without AKI were compared to determine factors associated with increased odds of AKI, focusing on vancomycin dose. Results: Of 175 patients included, 24 (13.7%) met AKI criteria. In a multivariate regression, likelihood of AKI increased with each 5 mg/kg increase in vancomycin dose (odds ratio [OR] = 1.16; 95% CI = 1.01-1.33). Odds of AKI increased with each additional day of therapy (OR = 1.11; 95% CI = 1.01-1.22) and use of concomitant nephrotoxic medications (OR = 5.02; 95% CI = 1.09-23.19). The study was limited by small sample size and retrospective design. Conclusions: AKI was common in children receiving vancomycin. Higher doses of vancomycin were associated with increased odds of AKI. The risks and benefits of higher vancomycin dosing should be considered for each patient. Patients should be monitored closely for AKI, especially with higher doses, extended durations of therapy, or concomitant use of nephrotoxic medications.

Are Elevated Vancomycin Serum Trough Concentrations Achieved Within the First 7 Days of Therapy Associated With Acute Kidney Injury in Children?

BACKGROUND

In 2008, the empiric vancomycin dosing recommendation in children at our institution was changed from 40 to 60 mg/kg per day. Subsequently, an increased incidence of acute kidney injury (AKI) in patients receiving vancomycin was suspected. The objective of this study was to evaluate AKI in children receiving vancomycin and to determine risk factors for AKI development.

METHODS

Medical records of patients aged 30 days through 17 years who received vancomycin for at least 72 hours between January and December 2007 (40 mg/kg per day) and January and December 2010 (60 mg/kg per day) were reviewed. Patients with cystic fibrosis, an elevated baseline serum creatinine, or without a serum creatinine concentration obtained after receipt of vancomycin were excluded. Acute kidney injury was defined using adapted pediatric RIFLE criteria as an increase in serum creatinine from baseline of 50% or more.

RESULTS

Acute kidney injury occurred in 19.4% of the 859 children included, with no difference between the 2007 and 2010 periods (18.8% vs 20%, respectively; P = .636). Intensive care unit admission (odds ratio [OR], 1.86; 95% confidence interval [CI], 1.20-2.94) and an initial vancomycin trough concentration ≥15 mg/L (OR, 2.18; 95% CI, 1.21-3.92) were determined to be significantly associated with AKI.

CONCLUSIONS

These results suggest an initial vancomycin serum trough concentration of ≥15 mg/L and intensive care unit admission are predictors of AKI in this pediatric 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.

Desired vancomycin trough serum concentration for treating invasive methicillin-resistant Staphylococcal infections

Vancomycin area under the curve/minimal inhibitory concentration (AUC/MIC) >400 best predicts the outcome when treating invasive methicillin-resistant Staphylococcus aureus infection; however, trough serum concentrations are used clinically to assess the appropriateness of dosing. We used pharmacokinetic modeling and simulation to examine the relationship between vancomycin trough values and AUC/MIC in children receiving vancomycin 15 mg/kg every 6 hours and methicillin-resistant Staphylococcus aureus MIC of 1 μg/mL. A trough of 7-10 μg/mL predicted achievement of AUC/MIC >400 in >90% of children.

Vancomycin Dosing Practices, Trough Concentrations, and Predicted Area Under the Curve in Children With Suspected Invasive Staphylococcal Infections

Recent guidelines recommend empiric vancomycin dosing of 60 mg/kg per day and consideration of higher trough concentrations (15-20 mcg/mL) in children with invasive infections. In this study, we report a retrospective review evaluating the dose/trough relationship and predicted area under the curve in pediatric patients receiving vancomycin for invasive staphylococcal infections.

The effect of age and weight on vancomycin serum trough concentrations in pediatric patients

BACKGROUND

Vancomycin treatment failure has been associated with low serum vancomycin trough concentrations, prompting recommendations to increase the daily doses in adults and children. Despite more aggressive vancomycin dosing, there continues to be significant variability in vancomycin trough concentrations in pediatric patients.

METHODS

To determine if vancomycin trough concentrations in pediatric patients differ by age and weight, we reviewed records of hospitalized patients who received vancomycin between 2008 and 2012. Patients were divided into groups that received vancomycin 40 mg/kg/day (2008-2009) or 60 mg/kg/day (2010-2012). Vancomycin trough concentrations were compared between groups and within the 60 mg/kg/day group, stratified by patient age and weight.

RESULTS

After increasing the vancomycin dose from 40 to 60 mg/kg/day, initial trough concentrations increased significantly in patients younger than 2 and greater than 6 years of age, but not in patients between the ages of 2 and 5 years. In the 60 mg/kg/day group, only 16.7% of patients between 2 and 5 years of age had initial trough concentrations in the therapeutic range (10-20 μg/ml). Initial trough concentrations were therapeutic in a greater proportion of patients ages 6-12 years (38.7%) and 13-18 years (63.0%). Patients between the ages of 13 and 18 had the highest proportion of supratherapeutic initial vancomycin trough concentrations (14.8%). Patients weighing over 50 kg had significantly higher trough concentrations than patients  50 kg or less (17.1 μg/ml vs 9.3 μg/ml, p<0.001).

CONCLUSION

Although increasing the vancomycin dose from 40 to 60 mg/kg/day led to a significant increase in vancomycin trough concentrations, a large proportion of patients receiving 60 mg/kg/day of vancomycin had trough concentrations outside of the therapeutic range. Specifically, patients younger than 6 years tended to have low trough concentrations, whereas adolescents and children over 50 kg were more likely to have elevated trough concentrations. Vancomycin dosing strategies in pediatric patients should consider age and weight as well as renal function and indication.

Vancomycin trough concentrations in overweight or obese pediatric patients

STUDY OBJECTIVES

To compare vancomycin trough concentrations in overweight or obese pediatric patients to those with normal body habitus, after initial dosing based on total body weight (TBW).

DESIGN

Retrospective observational case-control study.

SETTING

Free-standing academic pediatric hospital.

PATIENTS

Forty-two overweight or obese pediatric patients were matched to 84 children of normal body habitus (NBH).

MEASUREMENTS AND MAIN RESULTS

Empiric vancomycin dosing was based on TBW and guided by an age-stratified dosing algorithm previously developed at our center. Initial steady-state vancomycin trough concentrations were retrieved from the electronic medical record. Overweight and obese children had significantly higher initial vancomycin trough concentrations compared with children who had an NBH (median 14.4 μg/ml vs 10.5 μg/ml, p<0.001). Initial vancomycin trough concentrations above 20 μg/ml occurred more often in overweight and obese children (p=0.016). Our dosing algorithm suggested that initial vancomycin trough concentrations below 10 μg/ml occurred significantly more often in children with NBH (p<0.001).

CONCLUSIONS

Overweight and obese pediatric patients may have elevated initial vancomycin trough concentrations when empiric dosing is based on TBW. Special attention to therapeutic drug monitoring is warranted in all children.

Evaluation of a pediatric continuous-infusion vancomycin therapy guideline

PURPOSE

An institutional guideline for converting pediatric patients to continuous-infusion vancomycin (CIV) therapy if therapeutic targets are not achieved with intermittent i.v. dosing was evaluated.

METHODS

All patients within a specified age range (>6 months but <19 years) who were converted to CIV therapy for pneumonia or osteomyelitis during the 2 years after guideline implementation were included in the evaluation. The guideline calls for conversion to CIV therapy if goals for trough serum vancomycin concentration (SVC) are not attained with escalating intermittent-infusion vancomycin (IIV) dosing. Primary outcome measures included the rate of attainment of the goal steady-state trough SVC (15-20 mg/L), preferably within 24-48 hours, the adequacy of an empirical dosing strategy, and adverse events. Secondary study outcomes included final vancomycin doses and the time to attainment of therapeutic SVCs.

RESULTS

Within 24-48 hours after conversion to CIV therapy, the mean initial plateau SVC in the evaluated cases (n = 15) was 20.2 mg/L; the mean of all SVCs was 19.1 mg/L. The range of dosages required to achieve a plateau SVC of 15 mg/L was 23.8-65.4 mg/kg/day (median, 41 mg/kg/day). The mean ± S.D. vancomycin dosage at the end of CIV therapy was 44.3 ± 12.8 mg/kg/day. Monitoring of serum creatinine, urine output, and glomerular filtration rate indicated that no patients developed nephrotoxicity during CIV therapy.

CONCLUSION

Conversion from IIV to CIV therapy in selected pediatric patients appeared to be safe and well tolerated, with few adverse effects noted. Using the institutional CIV dosing guideline, goal plateau SVC values were attained in most patients within 24-48 hours.

Analysis of vancomycin therapeutic drug monitoring trends at pediatric hospitals

BACKGROUND

Vancomycin treatment failures in adults with methicillin-resistant Staphylococcus aureus bacteremia are well documented despite established therapeutic monitoring consensus recommendations. Vancomycin use in children has unique challenges, and consensus guidelines are lacking. We evaluated trends in vancomycin monitoring in children and estimated the impact of adult guidelines on patterns of vancomycin use.

METHODS

A retrospective, descriptive study was designed. Data were obtained from the Pediatric Health Information System from 40 not-for-profit, tertiary care pediatric hospitals in the United States. Patients receiving vancomycin during hospitalizations ending July 1, 2007 through June 30, 2011 were included, and the number of vancomycin monitoring determinations per course of therapy was queried. Vancomycin utilization and monitoring practices were evaluated across institutions, age groups and time intervals.

RESULTS

A total of 104,586 patients met study criteria. The mean duration of vancomycin administration was 5 (median 3, range 1-257) days. A mean of 1 (median 1, range 0-186) serum vancomycin concentration was obtained per patient; 46% of patients had none. Eighty-one percent of those receiving vancomycin more than 3 days had monitoring performed at least once. Monitoring practices did not correlate with length of therapy (r² = 0.11). Monitoring frequency increased across all age groups (P < 0.05) after publication of adult guidelines in January 2009.

CONCLUSIONS

Vancomycin monitoring practices are highly variable in children admitted to pediatric hospitals. The frequency with which serum vancomycin concentrations were monitored in children increased after the publication of the adult guidelines. Pediatric consensus guidelines should be developed to optimize patient care and resource utilization.

Systematic review and meta-analysis of vancomycin-induced nephrotoxicity associated with dosing schedules that maintain troughs between 15 and 20 milligrams per liter

In an effort to maximize outcomes, recent expert guidelines recommend more-intensive vancomycin dosing schedules to maintain vancomycin troughs between 15 and 20 mg/liter. The widespread use of these more-intensive regimens has been associated with an increase in vancomycin-induced nephrotoxicity reports. The purpose of this systematic literature review is to determine the nephrotoxicity potential of maintaining higher troughs in clinical practice. All studies pertaining to vancomycin-induced nephrotoxicity between 1996 and April 2012 were identified from PubMed, Embase, Cochrane Controlled Trial Registry, and Medline databases and analyzed according to Cochrane guidelines. Of the initial 240 studies identified, 38 were reviewed, and 15 studies met the inclusion criteria. Overall, higher troughs (≥ 15 mg/liter) were associated with increased odds of nephrotoxicity (odds ratio [OR], 2.67; 95% confidence interval [CI], 1.95 to 3.65) relative to lower troughs of <15 mg/liter. The relationship between a trough of ≥ 15 mg/liter and nephrotoxicity persisted when the analysis was restricted to studies that examined only initial trough concentrations (OR, 3.12; 95% CI, 1.81 to 5.37). The relationship between troughs of ≥ 15 mg/liter and nephrotoxicity persisted after adjustment for covariates known to independently increase the risk of a nephrotoxicity event. An incremental increase in nephrotoxicity was also observed with longer durations of vancomycin administration. Vancomycin-induced nephrotoxicity was reversible in the majority of cases, with short-term dialysis required only in 3% of nephrotoxic episodes. The collective literature indicates that an exposure-nephrotoxicity relationship for vancomycin exists. The probability of a nephrotoxic event increased as a function of the trough concentration and duration of therapy.