An evaluation of initial vancomycin dosing in infants, children, and adolescents

Vancomycin dosing required to achieve a therapeutic level in children post-surgical correction of congenital heart disease

The vancomycin dosing range for safe and effective treatment remains uncertain for children who had corrective surgery for a congenital heart disease (CHD). We aimed to determine the vancomycin dosing requirements for this subgroup of patients. This prospective cohort study included children younger than 14 years old with CHD who received intravenous vancomycin for at least 3 days at the Pediatric Cardiology section of King Abdulaziz Medical City, Riyadh. In total, 140 pediatric patients with CHD were included with a median age of 0.57 years (interquartile range 0.21-2.2). The mean vancomycin total daily dose (TDD), 37.71 ± 6.8 mg/kg/day, was required to achieve a therapeutic trough concentration of 7-20 mg/L. The patient's age group and the care setting were significant predictors of the vancomycin dosing needs. Neonates required significantly lower doses of 34 ± 6.03 mg/kg/day (P = .002), and young children higher doses of 43.97 ± 9.4 mg/kg/day (P = .003). The dosage requirements were independent of the type of cardiac lesion, cardiopulmonary surgery exposure, sex, and BMI percentile. However, the patients in the pediatric cardiac ward required higher doses of vancomycin 41.08 ± 7.06 mg/kg/day (P = .039). After the treatment, 11 (8.5%) patients had an elevated Scr, and 3 (2.3%) patients developed AKI; however, none of the patients' sociodemographic factors or clinical variables, or vancomycin therapy characteristics was significantly associated with the renal dysfunction. Overall, the vancomycin TDD requirements are lower in pediatric post-cardiac surgery compared to non-cardiac patients and are modulated by several factors.

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.

The relationship between vancomycin AUC/MIC and trough concentration, age, dose, renal function in Chinese critically ill pediatric patients

To assess the pharmacokinetic parameters of vancomycin in Chinese critically ill pediatric patients, children treated with vancomycin, hospitalized in the intensive care unit were included. Samples to determine peak and trough serum concentrations were obtained on the third day of treatment. Half-life was significantly longer in neonates and showed a decreasing trend in infants and children. In patients aged ≥1 month, AUC24 /MIC ≥400 was achieved in 31.8% at the dose of 40 mg/kg/d, and in 48.7% at the dose of 60 mg/kg/d with an assumed MIC of 1 mg/L. Augmented renal clearance (ARC) was present in 27.3% of children, which was associated with higher vancomycin clearance and lower AUC values. A good correlation was observed between trough concentration and AUC24 , and the trough concentration that correlated with AUC24 of 400 were varied according to the dosage regimens, 8.42 mg/L for 6-hintervals, and 6.63 mg/L for 8-h intervals. To conclude, vancomycin trough concentration that related to the AUC24 of 400 was much lower in critically ill children than that in adults. The dosage of 60 mg/kg/day did not enough for producing AUC24 in the range of 400-600 mg h/L in critically ill children, especially in those with ARC.

Children may need higher vancomycin doses to achieve therapeutic levels

AIM

Vancomycin is frequently used in paediatric hospitals. Data suggest trough levels of 10-20 mg/L are needed to achieve bacterial killing. This study aimed to evaluate if commonly used dosing regimens are efficient in reaching these levels and if therapeutic drug monitoring (TDM) was appropriately used.

METHODS

All children receiving intravenous vancomycin at the Children´s Hospital Iceland between 2012 and 2016 were included. Vancomycin trough levels were registered. Student t test, Wilcoxon test and regression models were used for statistical analysis.

RESULTS

A total of 105 children received 163 vancomycin treatments (55/105 neonates). Average daily dose in neonates was 23.4 mg/kg/day and 38.4 mg/kg/day for older children. No TDM was done in 58 treatments (35.6%). First trough levels were <10mg/L in 52.4% and <15mg/L in 92% of cases. Therapeutic levels were less likely achieved in children with malignancy (11.8%) compared with others (36.8%, p = 0.09).

CONCLUSIONS

In more than half of the cases, trough drug levels were <10 mg/L and malignancy was associated with the lowest probability of reaching therapeutic levels. This study suggests that starting doses of vancomycin in children should be higher, especially in relation to malignant diseases and supports the importance of antibiotic stewardship to ensure optimal antibiotic use.

AUC- vs. Trough-Guided Monitoring of Vancomycin in Infants

OBJECTIVE

Improving vancomycin therapy with therapeutic drug monitoring is recommended. Over the past few years, a few studies have demonstrated that trough concentrations may not be the optimal parameter for monitoring vancomycin concentration and Area under the curve (AUC) should be used instead. In this study authors evaluate two methods to estimate the AUC. The first method is based on linear regression using only a trough concentration. The second method uses a simplified two-sample equation-based strategy to estimate the AUC.

METHODS

Data from 70 infant patients were collected retrospectively from their medical records at King Saud University Medical City. The prediction accuracy for vancomycin therapy monitoring was optimized by comparing the two methods for the AUC calculation, the simple linear regression and simplified two-sample equation-based strategy.

RESULTS

The target AUC > 400 μg × h/ml was achieved in 10%, 71%, and 100% of patients with trough concentration ranges of 5-10, 10-15, and > 15 μg/ml, respectively. There was a strong correlation between the predicted and observed AUC calculated using the simplified two-sample equation-based strategy (R² = 0.91, bias = -3.9%, precision =12%).

CONCLUSIONS

The target AUC > 400 μg × h/ml can be achieved at trough concentrations <15 μg/ml in most patients. Targeting trough concentrations >15 can lead to overdoing and increase risk of nephrotoxicity. The authors recommend estimating the AUC using the simplified two-sample equation strategy for more precise dosing of vancomycin. Using AUC-guided dosing instead of the trough-guided approach can prevent over dosing and reduce the risk of nephrotoxicity.

Clinical Pharmacokinetics of Vancomycin in Critically Ill Children

BACKGROUND AND OBJECTIVE

Critically ill children exhibit altered pharmacokinetic parameters of vancomycin, mainly due to altered renal excretion and volume of distribution (as a result of altered plasma protein concentrations). We assessed the pharmacokinetic parameters of vancomycin in this subpopulation.

METHODS

Vancomycin trough concentrations in critically ill children were obtained following first dose and at steady state. Using a one-compartment model, clearance (CL), volume of distribution (Vd), elimination half-life (t_1/2), and area under the time-concentration curve for 24 h (AUC_0-24) were estimated. Subgroup analyses were carried out, with patients differentiated based on age, renal clearance, outcome, and renal dysfunction. Protein-free vancomycin concentrations were calculated using a previously reported formula.

RESULTS

Twenty-two samples were evaluated for first-dose and 182 for steady-state pharmacokinetics, and similar pharmacokinetic parameter values were observed at first dose and at steady state. Only 36.4% and 47.3% of the samples attained the recommended AUC_0-24 (mg·hr/L) of > 400 at first dose and at steady state, while 62.5% of the patients with renal dysfunction achieved this target. Nearly 40% of the patients had augmented renal clearance (ARC), which was associated with higher CL, shorter t_1/2, and lower AUC values. Amongst the patients with ARC, none had AUC_0-24 (mg·hr/L) > 400 at first dose, while 16% achieved this target at steady state. Volume of distribution was significantly higher in infants and a decreasing trend was observed in toddlers, children, and older children at steady state. Children with renal dysfunction had lower CL, prolonged t_1/2, and higher AUC values than patients with normal renal clearance at first dose. A good correlation was observed between trough concentration and AUC_0-24, as corroborated by the area under the receiver operating characteristic curve. The median fraction of protein-free vancomycin was around 77%.

CONCLUSION

Vancomycin dosing strategies in younger children should be revisited, and increased doses should be considered for critically ill children with ARC in order to achieve therapeutic concentrations of AUC_0-24.

Drug Utilization Evaluation of Vancomycin among Patients in Jafar Ibn Auf Pediatric Hospital, 2018

Background: Vancomycin is an antibiotic of growing importance in the treatment of hospital-acquired infections; with a particular emphasis on its value in the fight against Methicillin-resistant Staphylococcus aureus. Increasing reports of Vancomycin resistance have raised concerns about the effectiveness of this drug. Drug utilization evaluation has an important role in controlling rational use of antibiotics to prevent the emergence of resistance. Methods: We conducted a retrospective 6-months study at Jafar Ibn Auf pediatric hospital. Data including patient's demographics, diagnosis, Dosage regimen, and treatment duration were reviewed. The concordance of practice with the Hospital Infection Control Practices Advisory Committee (HICPAC) guidelines and principles of antibiotic therapy was assessed. Results: 127 medical records were reviewed in this study. Sepsis (29%) and Pneumonia (19.6%) were the most common indications. Culture test was requested in 20.5% of patients. Monitoring of serum creatinine was carried in 81.1% of patients. Based on HICPAC guidelines vancomycin was administered appropriately in 67.7% percent of cases. Considering the infusion rate, most of patients with specific order were received vancomycin in 1 hour. Conclusions: The results showed that vancomycin was used empirically without subsequent adjustment of the antimicrobial agent according to culture and sensitivity data and lack of paying enough attention to the infusion rate and serum creatinine monitoring.

Drug Utilization Evaluation of Vancomycin among Patients in Jafar Ibn Auf Pediatric Hospital, 2018

Background: Vancomycin is an antibiotic of growing importance in the treatment of hospital-acquired infections; with a particular emphasis on its value in the fight against Methicillin-resistant Staphylococcus aureus. Increasing reports of Vancomycin resistance have raised concerns about the effectiveness of this drug. Drug utilization evaluation has an important role in controlling rational use of antibiotics to prevent the emergence of resistance. Methods: We conducted a retrospective 6-months study at Jafar Ibn Auf pediatric hospital. Data including patient's demographics, diagnosis, Dosage regimen, and treatment duration were reviewed. The concordance of practice with the Hospital Infection Control Practices Advisory Committee (HICPAC) guidelines and principles of antibiotic therapy was assessed. Results: 127 medical records were reviewed in this study. Sepsis (29%) and Pneumonia (19.6%) were the most common indications. Culture test was requested in 20.5% of patients. Monitoring of serum creatinine was carried in 81.1% of patients. Based on HICPAC guidelines vancomycin was administered appropriately in 67.7% percent of cases. Considering the infusion rate, most of patients with specific order were received vancomycin in 1 hour. Conclusions: The results showed that vancomycin was used empirically without subsequent adjustment of the antimicrobial agent according to culture and sensitivity data and lack of paying enough attention to the infusion rate and serum creatinine monitoring.

Vancomycin Use in a Paediatric Intensive Care Unit of a Tertiary Care Hospital

BACKGROUND

Vancomycin is one of the commonly used anti-microbial drugs in intensive care units (ICUs). Guidelines recommend maintaining therapeutic trough levels of vancomycin (10-20 mg/L). The success of achieving the recommended therapeutic concentration of vancomycin is influenced by several factors, and this is even more complex in children, particularly those admitted in the ICU. Hence, we carried out the present study in children admitted in the ICU who were administered vancomycin.

METHODS

We carried out a chart review of children admitted in the paediatric ICU unit of a tertiary care hospital over a period of 3 years. Information on their demographic factors, diagnoses, duration of hospital stay, vancomycin treatment (dose, frequency and time of administration) and concomitant drugs, and vancomycin trough levels were retrieved. Descriptive statistics were used for representing the demographic factors, and multivariable logistic regression analyses were carried out to assess the determining factors.

RESULTS

One-hundred and two children were identified, of whom 13 had renal dysfunction. Two-hundred and fifty-two vancomycin trough levels were available, of which only 25% were observed in the recommended range (10-20 mg/L) amongst patients without any renal dysfunction and 22% amongst patients with renal dysfunction. Vancomycin was administered intravenously at an average [standard deviation (SD)] dose (mg/dose) of 13 (3.9) mostly either thrice or four times daily. Even in patients receiving vancomycin as a definitive therapy, only 40.9% achieved the recommended trough levels. Lower trough levels were associated with an increased risk of mortality. Nearly 4% of the levels were above 20 mg/L (toxic range). Seven children were suspected to have acute kidney injury (AKI) during the course of therapy where the cumulative vancomycin dose and mortality rate was higher. Only one serum vancomycin level during augmented renal clearance was observed in the recommended range. All the patients received at least one concomitant drug that either had nephrotoxic potential or predominant renal elimination, and use of a greater number of such drugs was associated with an increased risk of AKI.

CONCLUSION

The current vancomycin dosing strategy is ineffective in achieving therapeutic trough levels in children admitted to the ICU. Sub-therapeutic vancomycin trough levels significantly increase the risk of mortality.

Vancomycin Therapeutic Regime Adjustment in Newborns and Infants with Bacterial Infection: Case Series

Background:

Vancomycin is used mostly to overcome infections caused by methicillinresistant microorganisms. There are no well-established administration protocols for neonates and infants, so the leak of a specific administration regime in that population may lead to serum concentrations beyond the specified range.

Objective:

This case series evaluated the pharmacokinetics adjustment from a vancomycin therapeutic regimen prescribed to neonates and infants with bacterial infection at a neonatal public hospital intensive- care-unit, with the primary purpose to verify cases of nephrotoxicity.

Methods:

Three neonates and four infants taking vancomycin therapy, hospitalized in a public hospital from November 2014 to March 2015, were included in the study. Vancomycin serum concentrations were determined by particle-enhanced-turbidimetric inhibition-immunoassay. The vancomycin concentrations were used for dose adjustment by USC*Pack-PC-Collection®, a non-parametric maximization program. The trough serum concentration range of 10 to 20mg.L-1 was considered therapeutic.

Results:

Three patients had serum concentration outside the reference-range, one with subtherapeutic, and two with supratherapeutic concentrations. All patients had concomitant use of drugs which interfered with vancomycin distribution and excretion pharmacokinetics parameters, including drugs that may enhance nephrotoxicity. One patient showed signs of acute renal damage, by low vancomycin and creatinine estimated clearances.

Conclusion:

The pharmacokinetic adjustment has been proven to be a useful and necessary tool to increase therapeutic efficacy and treatment benefits. The standard dose of vancomycin can be used to initiate therapy in neonates and infants admitted to the ICU, but after reaching the drug steady state, the dosing regimen should be individualized and guided by pharmacokinetic parameters.

Therapeutic Effect of Linezolid in Children With Health Care-Associated Meningitis or Ventriculitis

We evaluated the efficacy of linezolid treatment in 6 children with health care-associated meningitis or ventriculitis (HCAMV) caused by gram-positive cocci. All children were diagnosed and treated at the Ehime University Hospital between January 2010 and December 2017. Of these, 5 were treated with linezolid as an empirical therapy. In these 5 patients, vancomycin was initially used but was changed to linezolid because of cerebrospinal fluid (CSF) culture positivity (n = 3) and a high minimum inhibitory concentration of vancomycin (n = 2). The most common HCAMV pathogens were methicillin-resistant coagulase-negative staphylococci (n = 3). In 3 patients, vancomycin concentration was low in CSF but reached the target concentration in serum, while linezolid concentration was high in both CSF and serum. HCAMV treatment using antimicrobial agents with poor CSF penetration may increase the likelihood of therapy failure. Linezolid is more susceptible as the first-line treatment for HCAMV compared with vancomycin.

Use of Individual Pharmacokinetics to Improve Time to Therapeutic Vancomycin Trough in Pediatric Oncology Patients

OBJECTIVE

Optimization of vancomycin dosing is difficult in children, given rapid drug clearance and patient heterogeneity. We sought to evaluate the impact of dosing using individual pharmacokinetic parameters on time to goal trough concentration in pediatric oncology patients.

METHODS

A retrospective review was conducted to assess vancomycin dosing in the pediatric oncology unit at Loma Linda University Children's Hospital between January 2013 and August 2013 (standard dosing group [SDG]). These patients were compared to those in a prospective arm that used pharmacokinetic dosing (pharmacokinetic dosing group [PKG]) between March 2014 and May 2015. Outcomes included percent of patients reaching a target trough by the specified time points, number of dose adjustments, number of serum concentrations drawn, and number of patients with supratherapeutic troughs.

RESULTS

Of 35 patients meeting inclusion criteria for the SDG, 2 (5.7%) reached goal trough concentration by 48 hours, compared with 14 of 16 patients (87%) in the PKG (p = 0.0001). Significantly more patients reached their goal trough at each time point in the PKG. There was no difference in number of dose adjustments, but significantly more concentrations were drawn on average in the PKG (mean, 4.6 versus 3.1, p = 0.02). In the SDG and PKG, respectively, 1 patient and 3 patients had supratherapeutic trough concentrations (p = 0.09).

CONCLUSIONS

Dosing using individual pharmacokinetic parameters led to a significant reduction in time to attain the desired vancomycin trough concentration in our pediatric oncology patients. Given the wide variation in dose requirements in this and other studies, application of patient-specific pharmacokinetics is essential to optimize vancomycin dosing in pediatric patients.

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.

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.

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.

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.

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.

Implications of serum creatinine measurements on GFR estimation and vancomycin dosing in children

BACKGROUND

Different serum creatinine (sCr) assays may obtain different values in the same patient, causing discrepancies in estimated glomerular filtration rate (eGFR) and sCr-based vancomycin dosing calculations.

OBJECTIVE

To identify potential discrepancies in sCr concentrations obtained by different assays, the compensated Jaffe (sCr-Jaffe) and the enzymatic (sCr-enz), and to compare between the eGFR and vancomycin daily dose, based on these sCr values.

METHOD

sCr-Jaffe and, sCr-enz concentrations of 890 healthy children, aged 1-18 years, were available from the Canadian Laboratory Initiative in Pediatric Reference Intervals study in Ontario. For each subject, eGFR (eGFR-Jaffe, eGFR-enz) was calculated using the revised Schwartz equation, and vancomycin daily dose (Vdose-Jaffe, Vdose-enz) was calculated using a sCr-based pharmacokinetic model.

RESULT

Significant, age-related differences were found in sCr concentrations, and in subsequent eGFR and Vdose, between the two assays. In children aged 1-5 years, mean sCr-Jaffe was higher than sCr-enz (44.0 ± 5.0 vs. 27.7 ± 7.3 μmol/L, P < 0.001), leading to lower eGFR-Jaffe (83.2 ± 9.0 vs. 137.9 ± 27.1 mL/min/1.73m2, P < 0.001) and lower Vdose-Jaffe (44.7 ± 2.5 vs. 53.5 ± 5.1 mg/kg/24 h, P < 0.001).

CONCLUSION

Based on these findings, young children may be at risk for vancomycin under-treatment. Further research is needed to define the more accurate sCr assay in young children treated with renally excreted drugs.

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.

A randomized controlled trial of a vancomycin loading dose in children

BACKGROUND

Despite its frequent use, the optimal dosing regimen of intravenous vancomycin remains controversial. Achievement of therapeutic trough early in the course of illness may be beneficial. Our objective was to assess whether a loading dose of vancomycin would increase the proportion of children reaching target trough concentrations 8 hours after initiation of therapy.

METHODS

We enrolled hospitalized children aged 2-18 years prescribed vancomycin at Boston Children's Hospital between February 2011 and January 2012. Participants were randomized to receive a loading dose (30 mg/kg) or a conventional initial dose (20 mg/kg). These were followed by a 20 mg/kg/dose every 8 hours in both groups. Serum vancomycin concentrations were measured before the second and third doses. Pharmacokinetic parameters were calculated using individual and population pharmacokinetic models.

RESULTS

Two of nineteen (11%) loading dose recipients had a trough 15-20 mg/L before the second dose, compared with 0 of 27 in the conventional dose group (P=0.17). However, the median area under the curve/minimum inhibitory concentration estimates (for a hypothetical minimum inhibitory concentration=1 mg/L) were above 400 in both groups. Red man syndrome incidence was higher in loading dose recipients (48% vs. 24%, P=0.06).

CONCLUSIONS

A vancomycin loading dose did not result in earlier achievement of therapeutic trough concentrations in this study. However, the systemic exposure to vancomycin in children administered 60 mg/kg/day was adequate, despite lower than recommended measured trough levels. Therefore, the need for higher target trough concentrations should be questioned.

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.