Correlation of vancomycin dosing to serum concentrations in pediatric patients: a retrospective database review

DRUG-RELATED PROBLEMS IN CARDIAC NEONATES UNDER INTENSIVE CARE

Objective:

To determine the frequency and nature of the Drug Related Problems (DRP) in neonates with cardiac diseases admitted to an Intensive Care Unit.

Methods:

This prospective cross-sectional study was developed at the Neonatal Intensive Care Unit (NICU) of a teaching maternity hospital in Brazil from January 2014 to December 2016. All neonates diagnosed with any heart disease (congenital heart disease, cardiomyopathy, arrhythmias, etc.) and who were admitted to the NICU for more than 24 hours with at least one prescribed drug were included in the study. Demographic and clinical data were collected from the records of the institution’s clinical pharmacy service. DRP and their respective interventions were independently reviewed and classified by two pharmacists. DRP classification was performed through the Pharmaceutical Care Network Europe v6.2 system.

Results:

122 neonates were included in the study. The frequency of neonates exposed to DRP was 76.4% (confidence interval of 95% [95%CI] 65.9–82.0), with a mean of 3.2±3.8 cases/patient. In total, 390 DRP were identified, of which 49.0% were related to “treatment effectiveness”, 46.7% to “adverse reactions” and 1.0% to “treatment costs”. The medicines most involved in DRP were Vancomycin (10.2%; n=46), Meropenem (8.0%; n=36) and Furosemide (7.1%; n=32). Pharmacists performed 331 interventions, of which 92.1% were accepted by physicians and nurses.

Conclusions:

The study showed that DRP are very frequent in patients with cardiac diseases hospitalized in the NICU, predominating problems related to the effectiveness and safety of the drug treatment.

Treatment of Methicillin-Resistant Staphylococcus aureus (MRSA) Infections in Children: a Reappraisal of Vancomycin

PURPOSE OF REVIEW

In the last 50 years, vancomycin has been the agent of choice to treat infections due to methicillin-resistant Staphylococcus aureus (MRSA). However, vancomycin treatment failure is not uncommon, even when MRSA strains are fully susceptible to vancomycin. Treatment with vancomycin requires careful monitoring of drug levels as there is a potential for nephrotoxicity. Resistance to clindamycin is not infrequent, which also limits therapeutic options for treating infections due to MRSA in children. This paper reviews the current data on pharmacokinetics and pharmacodynamics and clinical efficacy of vancomycin in children.

RECENT FINDINGS

Resistance to vancomycin in MRSA (MIC >2 mg/L) is infrequent; there is increasing evidence in the literature that vancomycin maybe ineffective against increasing proportion of isolates with MICs between 1 and 2 mg/L. Recent studies and meta-analyses have demonstrated that strains with high vancomycin MICs are associated with poor outcomes especially in patients with bacteremia and deep tissue infections due to MRSA. This gradual increase in vancomycin MIC has been reported as MIC creep or vancomycin heteroresistance. Patients infected with MRSA isolates that exhibit MIC creep experience poorer clinical outcomes, including delayed treatment response, increased mortality, increase rate of relapse, and extended hospitalization. There are limited data to guide vancomycin dosing in children with MRSA. Although the vancomycin area under the curve AUC₂₄/MIC ratio > 400 has been shown to predict clinical efficacy in adults, this relationship has not been documented very well for treatment outcomes in MRSA infections in children. Use of higher vancomycin dosages in attempts to achieve higher trough concentrations has been associated with increased nephrotoxicity. New recently approved antibiotics including ceftaroline, dalbavancin, and tedizolid offer a number of advantages over vancomycin to treat staphylococcal infections: improved antimicrobial activity, superior pharmacokinetics, pharmacodynamics, tolerability, and dosing, including once-daily and weekly regimens, and less need for monitoring drug levels.

Magnetic Glycol Chitin-Based Hydrogel Nanocomposite for Combined Thermal and d-Amino-Acid-Assisted Biofilm Disruption

Bacterial biofilms are highly antibiotic resistant microbial cell associations that lead to chronic infections. Unlike free-floating planktonic bacterial cells, the biofilms are encapsulated in a hardly penetrable extracellular polymeric matrix and, thus, demand innovative approaches for treatment. Recent advancements on the development of gel-nanocomposite systems with tailored therapeutic properties provide promising routes to develop novel antimicrobial agents that can be designed to disrupt and completely eradicate preformed biofilms. In our study, we developed a unique thermoresponsive magnetic glycol chitin-based nanocomposite containing d-amino acids and iron oxide nanoparticles, which can be delivered and undergoes transformation from a solution to a gel state at physiological temperature for sustained release of d-amino acids and magnetic field actuated thermal treatment of targeted infection sites. The d-amino acids in the hydrogel nanocomposite have been previously reported to inhibit biofilm formation and also disrupt existing biofilms. In addition, loading the hydrogel nanocomposite with magnetic nanoparticles allows for combination thermal treatment following magnetic field (magnetic hyperthermia) stimulation. Using this novel two-step approach to utilize an externally actuated gel-nanocomposite system for thermal treatment, following initial disruption with d-amino acids, we were able to demonstrate in vitro the total eradication of Staphylococcus aureus biofilms, which were resistant to conventional antibiotics and were not completely eradicated by separate d-amino acid or magnetic hyperthermia treatments.

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.

Successfully treated infective endocarditis caused by methicillin-resistant Staphylococcus Aureus in extremely low birth weight infant

Survival rates of preterm infants have improved in the past few decades, and central venous catheters play an important role in the intensive medical treatment of these neonates. Unfortunately, these indwelling catheters increase the risk of intracardiac thrombosis, and they provide a nidus for microorganisms during the course of septicemia. Herein, we report a case of persistent bacteremia due to methicillin-resistant Staphylococcus aureus in an extremely low birth weight (ELBW) infant, along with vegetation observed on an echocardiogram, the findings which are compatible with a diagnosis of endocarditis. The endocarditis was successfully treated with antibiotic therapy, and the patient recovered without major complications. We suggest a surveillance echocardiogram for ELBW infants within a few days of birth, with regular follow-up studies when clinical signs of sepsis are observed.

Pediatric Assessment of Vancomycin Empiric Dosing (PAVED): a Retrospective Review

BACKGROUND

Pediatric studies and anecdotal experience suggest that current empiric vancomycin dosing does not reach serum trough concentration targets of at least 10 mg/L for uncomplicated infections or 15-20 mg/L for serious or complicated infections.

OBJECTIVES

This study reviewed vancomycin dosing and serum concentrations to (i) determine the proportion of patients who reached initial target concentrations; (ii) describe pharmacokinetic parameters; and (iii) compare patient-specific area-under-the-curve (AUC) values to population estimates using the Rodvold equation.

METHODS

Following ethics approval, data were extracted from medical records of 200 patients aged 1 month-18 years, who received intravenous (IV) vancomycin and had at least two pharmacokinetically evaluable serum concentrations.

RESULTS

Trough vancomycin concentrations of 10-15 and 15-20 mg/L were achieved in 25 (29%) and 2 (2%) patients receiving vancomycin 15 mg/kg IV every 6 h (q6 h) and 22 (20%) and 9 (8%) patients receiving vancomycin 20 mg/kg IV every 8 h (q8 h), respectively. Patients were stratified into four age groups (1 month-1 year, 1-6 years, 6-13 years and 13-18 years). Median (IQR) pharmacokinetic parameters were elimination rate constant 0.25 (0.09), 0.29 (0.07), 0.24 (0.10) and 0.22 (0.07) h(-1); volume of distribution 0.56 (0.20), 0.61 (0.21), 0.47 (0.26) and 0.49 (0.22) L/kg; and half-life 2.8 (1.1), 2.4 (0.5), 2.9 (1.1) and 3.2 (1.0) h, respectively. Median (IQR) AUCs were 458 (170), 338 (132), 478 (215) and 513 (179) mg h/L and population-estimated AUCs were 67 (44), 108 (70), 299 (102) and 454 (103) mg h/L (p < 0.05 for all groups).

CONCLUSIONS

Based on these findings, we recommend vancomycin 70 and 90 mg/kg/day divided q6 h for troughs of 10-15 and 15-20 mg/L, respectively (patients 1 month-6 years) and 60 mg/kg/day divided q8 h and 70 mg/kg/day divided q6 h, respectively (patients >6 years) to undergo further testing as initial dosing regimens. Furthermore, population estimates grossly underestimate vancomycin AUC in patients 1-18 years old and thus patient-specific parameters are required.

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.

Vancomycin dosing in healthy-weight, overweight, and obese pediatric patients

OBJECTIVES

With an increase in vancomycin resistance and the prevalence of obesity in children, alterations of vancomycin dosing regimens may be necessary to achieve target serum concentrations. The primary objective of this study was to describe initial vancomycin dosing with resulting serum concentrations in healthy-weight and overweight/obese children. Secondary objectives include comparing vancomycin dosing regimens of healthy-weight and overweight/obese patients that produced target trough serum concentrations and evaluating the likelihood of attaining target concentrations by patient characteristics.

METHODS

This retrospective review evaluated healthy-weight and overweight/obese patients, aged 2 to 18 years, who had vancomycin trough serum concentrations obtained between 2005 and 2010. Vancomycin dosing, initial trough serum concentrations, pharmacokinetic parameters, and patient demographics were collected for analysis. Target trough serum concentrations were defined as 10 to 20 mg/L.

RESULTS

The study included 98 patients (48 healthy weight, 50 overweight/obese) of which only 14 patients (14.2%, 6 healthy weight, 8 obese) reached a target trough serum concentration with empiric dosing. No difference was found between the mean daily dosing of vancomycin that produced target trough serum concentrations in healthy-weight or overweight/obese patients (53.63 mg/kg/day vs 51.6 mg/kg/day, respectively). Demographic or clinical characteristics were not found to be associated with the likelihood of target trough serum concentration attainment.

CONCLUSIONS

Vancomycin dosing in healthy-weight and overweight/obese pediatric patients did not reach target trough serum concentrations most of the time. In obtaining initial target serum concentrations, no dosing difference was identified for overweight/obese patients compared with healthy-weight patients. Alternate dosing strategies, therapeutic monitoring, and clinical outcomes should continue to be evaluated in this population.

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

Background. The pharmacokinetics of many medications change as we age, thus most would assume dosing strategies would adjust for these changes. The objective of this study is to evaluate the initial vancomycin dosing in three pediatric age groups based on measured serum trough concentrations. Methodology. This retrospective database review included patients aged from 1 month to 18 years old admitted to the Moses H. Cone Memorial Hospital. Patients had to have received vancomycin dosed at 15 mg/kg every 8 hours with an appropriately measured trough concentration. The primary outcome was to determine the percentage of patients in 3 pediatric age groups achieving therapeutic trough concentrations with the initial vancomycin dosing regimen. Results. Twenty-five patients were included in the study. None of the patients had therapeutic trough concentrations after receiving vancomycin 15 mg/kg every 8 hours. Only one patient had a supratherapeutic level, while all of the other patients had levels less than 10 mcg/mL. Conclusions. Vancomycin 15 mg/kg every 8 hours did not provide therapeutic serum trough concentrations for any pediatric age groups. Higher doses and/or more frequent dosing regimens need to be evaluated for each age group to determine the most appropriate strategies for producing therapeutic trough concentrations.