Pharmacokinetics and administration regimens of vancomycin in neonates, infants and children

Dose optimization and target attainment of vancomycin in children

Vancomycin is a glycopeptide antibiotic that has been adopted in clinical practice to treat gram-positive infections for more than 70 years. Despite vancomycin's long history of therapeutic use, optimal dose adjustments and pharmacokinetic/pharmacodynamic (PK/PD) target attainment in children are still under debate. Therapeutic drug monitoring (TDM) has been widely integrated into pediatric clinical practice to maximize efficacy and safety of vancomycin treatment. Area under the curve (AUC)-guided TDM has been recently recommended instead of trough-only TDM to ensure PK/PD target attainment of AUC0-24h/minimal inhibitory concentration (MIC) > 400 to 600 and minimize acute kidney injury risk. Bayesian forecasting in pediatric patients allows estimation of population PK to accurately predict individual vancomycin concentrations over time, and consequently total vancomycin exposure. AUC-guided TDM for vancomycin, preferably with Bayesian forecasting, is therefore suggested for all pediatric age groups and special pediatric populations. In this review we aim to analyze the current literature on the pediatric use of vancomycin and summarize the current knowledge on dosing optimization for target attainment in special patient populations.

Reappraisal of therapeutic vancomycin trough concentrations with empirical dosing in neonatal infections

BACKGROUND

Vancomycin is commonly used for neonatal sepsis. However, consensus on an empirical neonatal vancomycin regimen remains uncertain. We aimed to reappraise the therapeutic optimum concerning vancomycin trough concentrations with empirical dosing and to evaluate the relationship between trough concentrations and predicted 24-h area under the curve (AUC₂₄).

METHODS

This was a 3-year retrospective study. Neonates who were admitted to the neonatal intensive care unit with available vancomycin trough concentrations were enrolled. Trough levels were obtained before the fourth dose. Achievement of goal trough after implementing the vancomycin dosing regimen was based on the Practical Neonatology Medical Manual, published by the National Taiwan University College of Medicine.

RESULTS

A total of 46 neonates were included for analysis. Coagulase-negative staphylococci were the most commonly identified pathogens of sepsis. Among these patients, 22 achieved goal trough levels of 10-20 mcg/mL. Trough levels of 5-10 or >20 mcg/mL occurred in 13 and 11 patients, respectively. A moderately positive correlation between trough and predicted AUC₂₄ was found in all patients (Spearman's rho = 0.676, p < 0.001). In patients with body weight 1200-2000 g and postnatal age >7 days, the serum creatinine of those with trough levels >20 mcg/mL was significantly higher than those with goal trough levels (0.61 vs. 0.45 mg/dL, p = 0.01). Among those with trough levels >20 mcg/mL, 5 patients received ibuprofen for patent ductus arteriosus closing prior to vancomycin treatment (45%, 5/11), compared to only 3 patients with trough levels <20 mcg/mL (9%, 3/35) (p = 0.013).

CONCLUSION

Only half of the neonates receiving empirical vancomycin regimen achieved goal trough levels of 10-20 mcg/mL. Higher serum creatinine or ibuprofen treatment may increase the risk of overly high trough levels. The vancomycin regimen needs further validation and modification to provide adequate dosing for optimal use in neonates.

Relationship between Vancomycin Trough Serum Concentrations and Clinical Outcomes in Children: a Systematic Review and Meta-Analysis

To systematically evaluate the relationships between vancomycin trough serum concentrations and clinical outcomes in children using meta-analysis. Several databases, including PubMed, Elsevier, Web of Science, EMBASE, Medline, clinicaltrials.gov, the Cochrane Library, and three Chinese databases (Wanfang Data, China National Knowledge Infrastructure, and SINOMED), were comprehensively searched to obtain research articles on vancomycin use in children from inception through December 2021. All studies were screened and evaluated using the Cochrane systematic review method. Then, the feature information was extracted for meta-analysis. The evaluated results included clinical efficacy, vancomycin-associated nephrotoxicity, hepatotoxicity, ototoxicity, mortality, and microbial clearance. A total of 35 studies involving 4820 children were included in the analysis. The meta-analysis showed that compared with children with vancomycin trough concentrations <10 μg/mL, those with vancomycin trough concentrations ≥10 μg/mL had a higher clinical efficacy rate [OR: 2.23, 95% CI: 1.29 to 3.84, P = 0.004] and higher incidences of nephrotoxicity [OR: 2.76, 95% CI: 1.51 to 5.07, P = 0.001], ototoxicity [OR: 1.87, 95% CI: 1.08 to 3.23, P = 0.02] and microbial clearance [OR: 2.36, 95% CI: 1.53 to 3.64, P = 0.0001]. All-cause mortality [OR: 1.07, 95% CI: 0.45 to 2.53, P = 0.88] and hepatotoxicity [OR: 0.84, 95% CI: 0.46 to 1.53, P = 0.57] were similar between the two groups. Subgroup analysis showed that compared with children with vancomycin trough concentrations of 10 to 15 μg/mL, those with vancomycin trough concentrations >15 μg/mL had a higher incidence of nephrotoxicity [OR: 2.64, 95% CI: 1.28 to 5.43, P = 0.008], but there was no significant difference in clinical efficacy [OR: 0.85, 95% CI: 0.30 to 2.44, P = 0.76]. A vancomycin trough concentration of 10 to 15 μg/mL can improve clinical efficacy in children. Additionally, avoidance of trough concentrations >15 μg/mL can reduce the incidence of adverse reactions.

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Pharmacokinetics of Vancomycin in Pediatric Patients Receiving Intermittent Hemodialysis or Hemodiafiltration

INTRODUCTION

Vancomycin is a common antibiotic used to treat hemodialysis (HD) or hemodiafiltration (HDF)-related infections in pediatric patients, but optimal dosing remains unknown. This is the first observational study to characterize the pharmacokinetics and evaluate dosing of vancomycin in this population.

METHODS

Eligible patients received IV vancomycin 10 mg/kg per dose postdialysis followed by a series of serum vancomycin concentrations collected before, immediately after, 1 hour after, and 4 hours after dialysis. The pharmacokinetic parameters were estimated using 1- and 2-compartment models and a nonlinear least-squares algorithm.

RESULTS

Among 42 vancomycin courses in 16 patients, 1 compartment model had the best fit for observed data. The net drug removal was 43 ± 13% (39% for HD and 50% for HDF) from an average 3-hour HD/HDF session. The mean elimination constant was 0.28 h-1 (standard deviation [SD], 0.11 h-1) during the intradialytic period compared with 0.0049 h-1 (SD, 0.004 h-1) when off dialysis. The mean volume of distribution was 0.65 (SD, 0.19) L/kg. Duration of dialysis session and mode of dialysis (HD vs. HDF) were significant predictors of vancomycin pharmacokinetic parameters. Half-life was shorter for HDF compared with HD (2.1 vs. 3.5 hours).

CONCLUSIONS

Based on the simulations, an initial vancomycin dose of 10 mg/kg per dose and redosing postdialysis was optimal to achieve a vancomycin concentration range of 5 to 12 mg/L at 4 hours postdialysis and 24-hour area under the curve over minimum inhibitory concentration of ≥400 hours. Therapeutic drug monitoring is necessary to account for residual variability in vancomycin elimination in pediatric patients receiving HD/HDF.

Antimicrobial prescribing for treatment of serious infections caused by Staphylococcus aureus and methicillin-resistant Staphylococcus aureus in pediatrics: an expert review

Introduction: Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), remains a significant pathogen in children. Despite evidence of decreasing prevalence, MRSA bacteremia has been closely associated with complications, including certain infections (i.e. musculoskeletal and endovascular) linked to increased treatment failures.Areas covered: This expert review summarized recent published literature on the role of treatment, dosing and administration of antibiotics used to combat serious S. aureus infections in children. The pertinent antibiotics presented were vancomycin, oxazolidinones, semi-synthetic glycopeptides, daptomycin, tigecycline, novel cephalosporins, fosfomycin and lefamulin. Vancomycin has been the most commonly used antibiotic in empiric therapy for serious MRSA infection, with new key recommendations emphasizing a different approach to dosing and therapeutic monitoring. For other antibiotics, data remain limited or clinical trials are underway.Expert opinion: MRSA remains a significant pathogen in the pediatric population. As numerous therapeutic agents are available, many agents have limited data on usage in pediatric patients. Future studies require pharmacokinetic, safety and efficacy studies in pediatric patients to ensure appropriate therapeutic treatment and outcomes. Phage therapy has been used to treat deep-seated MRSA infections and is an emerging investigational treatment option.

The optimal trough-guided monitoring of vancomycin in children: Systematic review and meta-analyses

We carried out a systematic review and meta-analysis exploring the relationship between vancomycin (VCM) trough concentrations and its effectiveness and nephrotoxicity in pediatric patients. We conducted our analysis using MEDLINE, Web of Sciences, and Cochrane Register of Controlled Trials as electronic databases (June 29, 2019). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. We identified 16 studies that were eligible for the meta-analysis. A total of 351 and 3,266 patients were included in the analysis for effectiveness and nephrotoxicity, respectively. Pediatric MRSA infection patients with VCM trough concentrations ≥ 10 μg/mL had significantly lower treatment failure rates (OR 0.54, 95% CI 0.30-0.96). The incidence of nephrotoxicity was significantly higher in trough concentrations ≥ 15 μg/mL than when they were < 15 μg/mL (OR 3.02, 95% CI 2.08-4.38). We identified the optimal VCM trough concentrations associated with effectiveness and nephrotoxicity in pediatric patients with MRSA infection. Further prospective studies are needed to find optimal dosing and monitoring strategy on VCM in pediatric population.

Chlorogenic acid prevents vancomycin-induced nephrotoxicity without compromising vancomycin antibacterial properties

Vancomycin (VCM) is an effective chemotherapeutic agent commonly used against gram-positive microorganisms but has serious nephrotoxic side effects that limit its effectiveness. New therapeutics and strategies are urgently needed to combat VCM associated nephrotoxicity. In this study, we determined the protective effect of chlorogenic acid (CA) in a rat model of VCM-induced nephrotoxicity. VCM administration led to markedly elevated blood urea nitrogen and serum creatinine levels that could be prevented with CA co-administration. VCM-mediated oxidative stress was also significantly attenuated by CA as reflected by decreased malondialdehyde and nitric oxide in VCM-treated kidneys. CA administration also prevented the VCM-mediated decrease in the renal antioxidative enzyme activities of glutathione reductase, glutathione peroxidase, and catalase and led to increased levels of reduced glutathione that had been depleted by VCM. Moreover, CA administration clearly inhibited VCM-induced expression of nuclear factor-kappa B, inducible nitric oxide synthase and the downstream pro-inflammatory mediators tumor necrosis factor-α and interleukins 1β and 6. Apoptotic markers were also markedly down-regulated with CA. Overall, CA treatment mitigated VCM-induced oxidative and nitrosative stresses and countered the apoptotic and inflammatory effects of VCM. Notably, CA did not affect the antibacterial activity of VCM in vitro.

Vancomycin Disposition following Intraperitoneal Administration in Children Receiving Peritoneal Dialysis

Background

Little information is available on the disposition of vancomycin during chronic peritoneal dialysis (PD) in children. The primary objective of this study was to investigate the disposition of vancomycin following intraperitoneal (IP) administration in children receiving short-dwell [ e.g., automated PD (APD)] and long-dwell [ e.g., continuous ambulatory PD (CAPD)] PD.

Methods

A 6-hour exchange containing vancomycin 500 mg/L, using an exchange volume of 1100 mL/m2body surface area (BSA), was followed by 4-, 6-, and 8-hour antibiotic-free exchanges. The 8-hour exchange was followed by three to four 90-minute antibiotic-free exchanges. Serial blood and dialysis effluent samples were obtained and analyzed for vancomycin concentration by high-pressure liquid chromatography. Pharmacokinetic parameters were computed using noncompartmental methods.

Results

The bioavailability of vancomycin during a 6-hour IP exchange was 70% ± 5%, resulting in a delivered dose of 12.0 ± 1.8 mg/kg, and a 6-hour serum vancomycin concentration of 23.3 ± 7.2 μg/mL. Total body vancomycin clearance measured 10.72 ± 4.52 mL/minute/1.73 m2BSA, while clearance attributable to PD measured 2.78 ± 1.08 mL/min/1.73 m2BSA and accounted for 29% ± 11% of total vancomycin clearance. Dialysis clearance during long-dwell (CAPD) and short-dwell (APD) regimens was similar, measuring 2.46 ± 1.04 and 3.09 ± 1.28 mL/min/1.73 m2BSA, accounting for 25% ± 13% and 32% ± 12% of total body clearance respectively.

Conclusions

Intraperitoneal absorption and dialysis clearance of vancomycin in children receiving PD are similar to those reported in adult dialysis patients. In contrast, total body clearance of vancomycin appears to be increased and the elimination half-life decreased in children, due to increased elimination by non-renal nondialysis routes. For intermittent IP vancomycin therapy in children with peritonitis, an IP load containing vancomycin 1000 mg/L (or 30 mg/kg), followed a single full-fill (1100 mL/m2BSA) daily exchange, containing vancomycin 250 mg/L (or 7.5 mg/kg), from day 2 until the end of treatment will maintain a vancomycin dialysate concentration of >4 μg/mL.

Age-dependent changes in vancomycin-induced nephrotoxicity in mice

Vancomycin hydrochloride (VCM) is a glycopeptide antibiotic that is commonly used to eradicate methicillin-resistant gram-positive cocci, despite its nephrotoxic side effects. Elderly people are particularly susceptible to developing VCM-induced nephrotoxicity. However, the precise mechanism by which VCM induces nephrotoxicity in elderly people is not completely understood. Therefore, we investigated VCM-induced nephrotoxicity in mice of different ages. VCM was injected intraperitoneally into mice at 1, 3, 6, 12, and 24 months of age at a dosage of 400 mg/kg body weight for 3 and 14 days. Twenty-four hours after the last injection, we examined plasma creatinine levels and histopathological alterations in the kidneys. VCM administration increased plasma creatinine levels, and these values gradually increased to higher levels with aging. The histological examination revealed renal tubular degeneration, such as brush-border atrophy, apoptosis/necrosis of the tubular epithelium, and epithelial desquamation, that gradually became more severe with aging. Furthermore, immunohistochemical staining with anti-CD10 and anti-single-stranded DNA antibodies revealed damaged renal proximal tubules with marked dilatation, as well as numerous apoptotic cells, and these features increased in severity in 12- and 24-month-old mice receiving VCM. Based on these results, aged mice were highly susceptible to kidney damage induced by VCM administration. In addition, proximal tubular epithelial cells likely underwent apoptosis after the administration of VCM. This report is the first to document VCM-induced nephrotoxicity in mice of different ages. Thus, this mouse model could be useful for understanding the mechanisms of VCM-induced nephrotoxicity in the elderly.

Continuous intravenous vancomycin in children with normal renal function hospitalized in hematology-oncology: prospective validation of a dosing regimen optimizing steady-state concentration

Continuous intravenous (IV) infusion has been shown to be the best option to administer vancomycin because of its time-dependent bactericidal activity. Available IV vancomycin dosing guidelines in pediatrics with normal renal function leads to less than 50% of patients achieving a vancomycin serum concentration (Css) in the target range (15-20 mg/L). The primary objective of this study was to prospectively validate an age-based dosing regimen in pediatric oncology-hematology. The secondary objective was to investigate the influence on Css attainment of different variables. A continuous IV dosing nomogram was built by retrospective study (2000-2010) on Bayesian dosing adjustments performed in 161 patients. This study assessed the prospective validation of this age-based nomogram and the influence on Css attainment of variables as the gender, underlying disease (oncology or hematology), and hematopoietic stem cell transplantation (HSCT) before receiving vancomycin therapy. A total of 94 patients aged from 4.3 months to 17.9 years old with normal renal function were eligible for the prospective validation. Fifty-five of those patients (58.5%) achieved the target range of vancomycin Css. There was no significant difference between age groups (P = 0.816) and no influence of gender (P = 0.500). There was a nonsignificant trend to a better target attainment in oncology patients (69.2% vs. hematology 54.4%, P = 0.142) and patients who did not undergo HSCT (63.3% vs. 33.3%, P = 0.031). This study proposed an age-based nomogram prospectively validated which near 60% of patients of each age class achieving the target range of Css.

Vancomycin AUC/MIC and Corresponding Troughs in a Pediatric Population

OBJECTIVES

Adult guidelines suggest an area under the curve/minimum inhibitory concentration (AUC/MIC) > 400 corresponds to a vancomycin trough serum concentration of 15 to 20 mg/L for methicillin-resistant Staphylococcus aureus infections, but obtaining these troughs in children are difficult. The primary objective of this study was to assess the likelihood that 15 mg/kg of vancomycin every 6 hours in a child achieves an AUC/MIC > 400.

METHODS

This retrospective chart review included pediatric patients >2 months to <18 years with a positive S aureus blood culture and documented MIC who received at least two doses of vancomycin with corresponding trough. Patients were divided into two groups: group 1 initially receiving ≥15 mg/kg every 6 hours, and group 2 initially receiving any other dosing ranges or intervals. AUCs were calculated four times using three pharmacokinetic methods.

RESULTS

A total of 36 patients with 99 vancomycin trough serum concentrations were assessed. Baseline characteristics were similar between groups. For troughs in group 1 (n = 55), the probability of achieving an AUC/MIC > 400 ranged from 16.4% to 90.9% with a median trough concentration of 11.4 mg/L, while in group 2 (n = 44) the probability of achieving AUC/MIC > 400 ranged from 15.9% to 54.5% with mean trough concentration of 9.2 mg/L. The AUC/MICs were not similar between the different pharmacokinetic methods used; however, a trapezoidal equation (Method A) yielded the highest correlation coefficient (r² = 0.59). When dosing every 6 hours, an AUC/MIC of 400 correlated to a trough serum concentration of 11 mg/L.

CONCLUSIONS

The probability of achieving an AUC/MIC > 400 using only a trough serum concentration and an MIC with patients receiving 15 mg/kg every 6 hours is variable based on the method used to calculate the AUC. An AUC/MIC of 400 in children correlated to a trough concentration of 11 mg/L using a trapezoidal Method to calculate AUC.

What do I need to know about glycopeptide antibiotics?

Glycopeptides have been crucial in the fight against Gram-positive pathogens with their use within paediatrics becoming ever prevalent. This article reviews the pharmacology of the commonly used glycopeptides, vancomycin and teicoplanin, and discusses the practical aspects of their use in the clinical setting.

A Systematic Review of Vancomycin Dosing and Monitoring in Burn Patients

Vancomycin pharmacokinetics are significantly altered following burn injury, requiring a higher total daily dose to achieve adequate serum concentrations. Wide interpatient variability necessitates close, frequent monitoring of serum concentrations for efficacy and safety. The aim of this study is to systematically evaluate published data regarding vancomycin pharmacokinetic alterations in burn patients, to determine whether evidence-based recommendations for dosing and monitoring can be formulated, and to identify future research opportunities. The systematic review included studies published in English, involved human subjects with at least a 10% TBSA burn who received vancomycin intravenously, and obtained serum concentration(s). Database searches returned 130 titles for review. Twelve studies met a priori inclusion criteria. The most common dosing regimens in adult and pediatric patients were 5 to 20 mg/kg/dose every 6 to 8 hours. Mean trough concentrations were 7.24 ± 1.5 mg/L. Only 12.5% of reported trough concentrations were within the currently recommended range of 10 to 20 mg/L. Although no consistent dosing recommendations were provided, all studies recommended close monitoring of trough concentrations. Based on limited clinical outcomes data, standardized recommendations for vancomycin dosing and monitoring in burn patients cannot be made. Higher total daily doses (40-70 mg/kg/day) and increased dosing frequency (every 6-12 hr in adults) may be necessary to achieve current target trough concentrations. Future research goals include prospective investigation of clinical outcomes related to initial doses, loading doses, monitoring peak and trough concentrations, and adverse effects. Further data on the effects of burn size, concomitant diseases, inhalation injury, and time since injury may improve the accuracy of vancomycin dosing in burn patients.

Serum levels of vancomycin: is there a prediction using doses in mg/kg/day or m2/day for neonates?

Coagulase-negative Staphylococcus has been identified as the main nosocomial agent of neonatal late-onset sepsis. However, based on the pharmacokinetics and erratic distribution of vancomycin, recommended empirical dose is not ideal, due to the inappropriate serum levels that have been measured in neonates. The aim of this study was to evaluate serum levels of vancomycin used in newborns and compare the prediction of adequate serum levels based on doses calculated according to mg/kg/day and m²/day. This is an observational reprospective cohort at a referral neonatal unit, from 2011 to 2013. Newborns treated with vancomycin for the first episode of late-onset sepsis were included. Total dose in mg/kg/day, dose/m²/day, age, weight, body surface and gestational age were identified as independent variables. For predictive analysis of adequate serum levels, multiple linear regressions were performed. The Receiver Operating Characteristic curve for proper serum vancomycin levels was also obtained. A total of 98 patients received 169 serum dosages of the drug, 41 (24.3%) of the doses had serum levels that were defined as appropriate. Doses prescribed in mg/kg/day and dose/m²/day predicted serum levels in only 9% and 4% of cases, respectively. Statistical significance was observed with higher doses when the serum levels were considered as appropriate (p < 0.001). A dose of 27 mg/kg/day had a sensitivity of 82.9% to achieve correct serum levels of vancomycin. Although vancomycin has erratic serum levels and empirical doses cannot properly predict the target levels, highest doses in mg/kg/day were associated with adequate serum levels.

Vancomycin Dosing and Pharmacokinetics in Postoperative Pediatric Cardiothoracic Surgery Patients

OBJECTIVES

This study compared vancomycin trough concentrations and pharmacokinetic parameters in pediatric cardiothoracic surgery (CTS) patients versus those in controls receiving 20 mg/kg/dose, intravenously, every 8 hours.

METHODS

A retrospective study was conducted in children <18 years of age, following CTS, versus an age-and sex-matched control group. The primary objective was to determine differences in trough concentrations between groups. Secondary objectives included comparisons of pharmacokinetics between groups and development of vancomycin-associated acute kidney injury (AKI), defined as a doubling in serum creatinine from baseline. Also dosing projections were developed to target an area-under-the-curve-to-minimum inhibitory concentration (AUC:MIC) ratio of ≥400.

RESULTS

Twenty-seven patients in each group were evaluated. Mean trough concentrations were significantly different between groups (CTS: 18.4 mg/L; control: 8.8 mg/L; p < 0.01). Vancomycin-associated acute kidney injury AKI was significantly higher in the CTS group than in controls (25.9% versus 0%, respectively, p<0.01). There were significant differences in vancomycin elimination rates, with a high degree of variability, but no statistical differences in other parameters. Based on dosing projections, CTS patients would require 21 to 88 mg/kg/day, with a dosage interval determined by the child's glomerular filtration rate to achieve the target AUC:MIC ≥400.

CONCLUSIONS

Vancomycin dosage of 20 mg/kg/dose intravenously every 8 hours achieved significantly higher trough concentrations in CTS patients than in controls. Pharmacokinetic parameters were highly variable in CTS patients, indicating more individualization of dosage is needed. A future prospective study is needed to determine whether the revised dosage projections achieve the AUC:MIC target and to determine whether these regimens are associated with less vancomycin-associated AKI.

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.

An investigation into the vancomycin concentration in the cerebrospinal fluid due to vancomycin intraventricular administration in newborns: a study of 13 cases

Treatment against shunt infection by transvenous antimicrobial treatment is difficult, with a high risk of relapse. Consequently, to maintain a sufficient cerebrospinal fluid (CSF) concentration, intraventricular administration is utilized in combination with the transvenous administration of vancomycin (VCM). Few studies have so far investigated the optimum administration dose for newborns and the concentration in the CSF. Therefore, we chronologically measured the VCM concentration in the CSF after VCM intraventricular administration in newborns and attempted to elucidate the optimum administration method.The participants consisted of newborns admitted to Juntendo University Neonatal intensive care unit from March 2007 to June 2011 who underwent interventricular shunting placement. VCM was intraventricularly administered to 10 patients for a total of 13 cases. The CSF concentration of VCM was chronologically measured at 12 to 120  hours following the intraventricular administration of VCM.The intraventricular administration groups with VCM of 20 (n = 6) and 10  mg (n = 2) had a high concentration in the CSF at 24  hours following administration (95-168  mg/L), with the concentration remaining high at 72  hours (13.2-72  mg/L). At the same time, in the 5  mg group (n = 5), the concentration in the CSF 24  hours following VCM administration was sufficiently maintained (33.2-62.9  mg/L), with a sufficient trough concentration still maintained at 72  hours (11.7-16.5  mg/L).The concentration in the CSF is prolonged in newborns, thus allowing a sufficient therapeutic range to be maintained even at an intraventricular administration of 5  mg. It is therefore believed that the monitoring of the CSF is very important regarding the administration interval because the VCM concentration in the CSF differs depending on the case.

An evaluation of vancomycin dosing for complicated infections in pediatric patients

OBJECTIVE

To determine the incidence with which a vancomycin dosing regimen of 15 mg/kg per dose every 6 hours achieves steady-state trough concentrations of 15 to 20 mg/L in pediatric patients with complicated infections.

METHODS

We performed a retrospective chart review for patients admitted to our children's hospital between July 1, 2009, and June 30, 2011. Patients were included if they were between 1 month and 18 years of age, had at least 1 steady-state vancomycin trough obtained, received an initial vancomycin dose of 15 mg/kg per dose every 6 hours, and were being treated for a diagnosis of meningitis, pneumonia, osteomyelitis, bacteremia/sepsis, or endocarditis.

RESULTS

Seventy-four patients were enrolled, mean age of 4.2±3.9 years and weight of 17.0±11.2 kg. Five (6.8%) patients obtained an initial trough of 15 to 20 mg/L. Patients between 1.0 and 5.9 years of age were significantly less likely to achieve an initial trough of 15 to 20 mg/L compared with other age groups evaluated (P=.041). Thirty-four patients with initial subtherapeutic troughs received a dose adjustment and a follow-up vancomycin trough. Of these patients, 15 (44.1%) achieved a trough between 15 and 20 mg/L. The median dose for patients achieving a therapeutic trough at any point during the study was 80 mg/kg per day.

CONCLUSIONS

A vancomycin dosing regimen of 15 mg/kg per dose every 6 hours is not likely to achieve a trough concentration of 15 to 20 mg/L in pediatric patients with complicated infections. An initial regimen of 80 mg/kg per day for these patients may be more likely to result in therapeutic steady-state concentrations of vancomycin.

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.

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.

Determination of vancomycin pharmacokinetics in neonates to develop practical initial dosing recommendations

Variability in neonatal vancomycin pharmacokinetics and the lack of consensus for optimal trough concentrations in neonatal intensive care units pose challenges to dosing vancomycin in neonates. Our objective was to determine vancomycin pharmacokinetics in neonates and evaluate dosing regimens to identify whether practical initial recommendations that targeted trough concentrations most commonly used in neonatal intensive care units could be determined. Fifty neonates who received vancomycin with at least one set of steady-state levels were evaluated retrospectively. Mean pharmacokinetic values were determined using first-order pharmacokinetic equations, and Monte Carlo simulation was used to evaluate initial dosing recommendations for target trough concentrations of 15 to 20 mg/liter, 5 to 20 mg/liter, and ≤20 mg/liter. Monte Carlo simulation revealed that dosing by mg/kg of body weight was optimal where intermittent dosing of 9 to 12 mg/kg intravenously (i.v.) every 8 h (q8h) had the highest probability of attaining a target trough concentration of 15 to 20 mg/liter. However, continuous infusion with a loading dose of 10 mg/kg followed by 25 to 30 mg/kg per day infused over 24 h had the best overall probability of target attainment. Initial intermittent dosing of 9 to 15 mg/kg i.v. q12h was optimal for target trough concentrations of 5 to 20 mg/liter and ≤20 mg/liter. In conclusion, we determined that the practical initial vancomycin dose of 10 mg/kg vancomycin i.v. q12h was optimal for vancomycin trough concentrations of either 5 to 20 mg/liter or ≤20 mg/liter and that the same initial dose q8h was optimal for target trough concentrations of 15 to 20 mg/liter. However, due to large interpatient vancomycin pharmacokinetic variability in neonates, monitoring of serum concentrations is recommended when trough concentrations between 15 and 20 mg/liter or 5 and 20 mg/liter are desired.

Considerations in the pharmacologic treatment and prevention of neonatal sepsis

The management of neonatal sepsis is challenging owing to complex developmental and environmental factors that contribute to inter-individual variability in the pharmacokinetics and pharmacodynamics of many antimicrobial agents. In this review, we describe (i) the changing epidemiology of early- and late-onset neonatal sepsis; (ii) the pharmacologic considerations that influence the safety and efficacy of antibacterials, antifungals, and immunomodulatory adjuvants; and (iii) the recommended dosing regimens for pharmacologic agents commonly used in the treatment and prevention of neonatal sepsis. Neonatal sepsis is marked by high morbidity and mortality, such that prompt initiation of antimicrobial therapy is essential following culture collection. Before culture results are available, combination therapy with ampicillin and an aminoglycoside is recommended. When meningitis is suspected, ampicillin and cefotaxime may be considered. Following identification of the causative organism and in vitro susceptibility testing, antimicrobial therapy may be narrowed to provide targeted coverage. Therapeutic drug monitoring should be considered for neonates receiving vancomycin or aminoglycoside therapies. For neonates with invasive fungal infections, the development of new antifungal agents has significantly improved therapeutic outcomes in recent years. Liposomal amphotericin B has been found to be safe and efficacious in patients with renal impairment or toxicity caused by conventional amphotericin B. Antifungal prophylaxis with fluconazole has also been reported to dramatically reduce rates of neonatal invasive fungal infections and to improve long-term neurodevelopmental outcomes among treated children. Additionally, several large multicenter studies are currently investigating the safety and efficacy of oral lactoferrin as an immunoprophylactic agent for the prevention of neonatal sepsis.

Vancomycin and gentamicin pharmacokinetic alterations in an adolescent amputee

A 14-year-old male with bilateral above-the-knee amputations presented to our hospital for treatment of a skin and soft-tissue infection. We report the experience of vancomycin and gentamicin therapy in this patient. Because these medications require weight-based dosages and pharmacokinetic monitoring of serum levels, it was necessary to obtain peak and trough levels of the two drugs in order to determine the pharmacokinetic differences in this patient compared to those in an adolescent male without amputations. To our knowledge, this is the first report describing pharmacokinetic differences in an adolescent amputee.

Use of antibacterial agents in the neonate: 50 years of experience with vancomycin administration

Neonatal sepsis, classified as either early or late onset, has specific pathogen distribution and infection rates in the different neonatal age groups. It is a major cause of mortality and morbidity and administration of antibiotics is urgently required for suspected or proven infection. Vancomycin is the first choice treatment of late onset sepsis due to resistant staphylococci. Although it has been used for more than 50 years, prescription remains a challenge in neonatal intensive care units for many reasons, including: high pharmacokinetic variability, numerous presentations, lack of consensus on dosing regimen and therapeutic drug monitoring. In addition, recent concerns about the increase in minimal inhibition concentration and other more generic problems have prompted reappraisal of the rational use of vancomycin. This article highlights the goal of optimising vancomycin therapy in the neonate and discusses future research directions. Specific attention is given to dosing optimisation of vancomycin to avoid resistance and maximise the likelihood of achieving the therapeutic target. Modelling and simulation approaches have clear advantages in dosing optimisation of antimicrobial agents in the neonate. Neonatologists and paediatric pharmacologists should work closely together to achieve this goal.

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

OBJECTIVES

Appropriate antimicrobial dosing maximizes therapeutic benefit while minimizing development of antimicrobial resistance. Common pediatric references recommend vancomycin dosing of 40 mg/kg/day divided every 6 to 8 hours for non-central nervous system infections, while some clinicians report utilizing higher initial doses to optimize efficacy. This study compares vancomycin serum concentrations following traditional dosing of 10 mg/kg/dose every 6 to 8 hours versus 15 to 20 mg/kg/dose every 6 to 8 hours.

STUDY DESIGN

Retrospective database review of vancomycin serum concentrations in pediatric patients.

RESULTS

Three hundred fifty-seven patients were analyzed. The mean peak concentration of the 10 mg/kg groups every 6 and every 8 hours were below 25 mg/L, whereas the mean peak concentrations of the 15 mg/ kg groups every 6 and 8 hours were within the 25-40 mg/L range (p < 0.001). The mean trough concentration of the 10 mg/kg group every 6 hours was within the 5-15 mg/L range while the 10 mg/kg group dosed every 8 hours was below target. However, the mean trough concentrations of the 15 mg/kg group dosed every 6 and 8 hours were both within the 5-15 mg/L range (p < 0.001).

CONCLUSIONS

Vancomycin doses of 15 mg/kg every 6 to 8 hours produce peak and trough serum concentrations within target range more often than 10 mg/kg every 6 to 8 hours.

Clinical pharmacokinetics of vancomycin in the neonate: a review

Neonatal sepsis is common and is a major cause of morbidity and mortality. Vancomycin is the preferred treatment of several neonatal staphylococcal infections. The aim of this study was to review published data on vancomycin pharmacokinetics in neonates and to provide a critical analysis of the literature. A bibliographic search was performed using PubMed and Embase, and articles with a publication date of August 2011 or earlier were included in the analysis. Vancomycin pharmacokinetic estimates, which are different in neonates compared with adults, also exhibit extensive inter-neonatal variability. In neonates, several vancomycin dosing schedules have been proposed, mainly based on age (i.e., postmenstrual and postnatal), body weight or serum creatinine level. Other covariates [e.g., extracorporeal membrane oxygenation (ECMO), indomethacin or ibuprofen, and growth restriction] of vancomycin pharmacokinetics have been reported in neonates. Finally, vancomycin penetrates cerebrospinal fluid (range = 7-42%). Renal function drives vancomycin pharmacokinetics. Because either age or weight is the most relevant covariate of renal maturation, these covariates should be considered first in neonatal vancomycin dosing guidelines and further adjusted by renal dysfunction indicators (e.g., ECMO and ibuprofen/indomethacin). In addition to the prospective validation of available dosing guidelines, future studies should focus on the relevance of therapeutic drug monitoring and on the value of continuous vancomycin administration in neonates.

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

STUDY OBJECTIVE

To evaluate the impact of a hospitalwide increase in the recommended vancomycin starting dose from 45 to 60 mg/kg/day on initial vancomycin trough concentrations in children suspected of having an invasive methicillin-resistant Staphylococcus aureus (MRSA) infection.

DESIGN

Retrospective medical record review.

SETTING

Dedicated children's hospital located in a tertiary care, academic medical center.

PATIENTS

A total of 182 children aged 1 month-12 years with normal renal function who had suspected MRSA infections treated with vancomycin during two different starting dose recommendation periods: 45 mg/kg/day divided every 8 hours during July 2006-June 2007 (low-dose group [88 children]) and 60 mg/kg/day divided every 6 hours during July 2008-June 2009 (high-dose group [94 children]).

MEASUREMENT AND MAIN RESULTS

Data on patient demographics, vancomycin doses, and initial vancomycin trough concentrations were collected. No significant demographic differences were noted between patients in the low-dose and high-dose groups. The mean ± SD initial vancomycin trough level increased from 7 ± 5 μg/ml in the low-dose group to 9 ± 5 μg/ml in the high-dose group (p<0.001). The percentage of patients with an initial trough level less than 5 μg/ml declined from 38% (33/88 children) in the low-dose group to 17% (16/94 children) in the high-dose group (p<0.001), whereas the percentage of patients with an initial trough concentration in the potentially adverse range (> 20 μg/ml) did not change between the two groups (2% vs 2%, p=0.9). Less than 14% (13/94 children) achieved a trough level in the range of 15-20 μg/ml in the high-dose group.

CONCLUSION

An increase in the recommended vancomycin starting dose to 60 mg/kg/day decreased the likelihood of an initial low vancomycin trough level (< 5 μg/ml), with no increase in the proportion of patients with trough levels in a potentially toxic range. The 60-mg/kg/day dose did not consistently achieve a vancomycin trough of 15-20 μg/ml, a goal suggested by some experts for adults. Comparative effectiveness studies are needed to directly evaluate vancomycin dosing regimens and clinical outcomes for children with invasive MRSA infections.

Population pharmacokinetics of vancomycin in premature Malaysian neonates: identification of predictors for dosing determination

The present study determined the pharmacokinetic profile of vancomycin in premature Malaysian infants. A one-compartment infusion model with first-order elimination was fitted to serum vancomycin concentration data (n = 835 points) obtained retrospectively from the drug monitoring records of 116 premature newborn infants. Vancomycin concentrations were estimated by a fluorescence polarization immunoassay. Population and individual estimates of clearance and distribution volume and the factors which affected the variability observed for the values of these parameters were obtained using a population pharmacokinetic modeling approach. The predictive performance of the population model was evaluated by visual inspections of diagnostic plots and nonparametric bootstrapping with replacement. Dosing guidelines targeting a value of > or =400 for the area under the concentration-time curve over 24 h in the steady state divided by the MIC (AUC(24)/MIC ratio) were explored using Monte Carlo simulation. Body size (weight), postmenstrual age, and small-for-gestational-age status are important factors explaining the between-subject variability of vancomycin pharmacokinetic parameter values for premature neonates. The typical population parameter estimates of clearance and distribution volume for a 1-kg premature appropriate-for-gestational-age neonate with a postmenstrual age of 30 weeks were 0.0426 liters/h and 0.523 liters, respectively. There was a 20% reduction in clearance for small-for-gestational-age infants compared to the level for the appropriate-for-gestational-age control. Dosage regimens based on a priori target response values were formulated. In conclusion, the pharmacokinetic parameter values for vancomycin in premature Malaysian neonates were estimated. Improved dosage regimens based on a priori target response values were formulated by incorporating body size, postmenstrual age, and small-for-gestational-age status, using Monte Carlo simulations with the model-estimated pharmacokinetic parameter values.

Role of the poly(ADP-ribose)polymerase activity in vancomycin-induced renal injury

The aim of the present study was to investigate the role of poly(ADP-ribose)polymerase (PARP) activity in vancomycin (VCM)-induced renal injury and to determine whether 1,5-isoquinelinediol (ISO), a PARP inhibitor agent, could be offered as an alternative therapy in VCM-induced renal impairment. Rats were divided into four groups as follows: (i) control (Group 1); (ii) VCM-treated (Group 2); (iii) VCM plus ISO-treated (Group 3); and (iv) ISO-treated (Group 4). VCM (200mg/kg, i.p., twice daily) was administered to Groups 2 and 3 for 7 days. ISO (3mg/kg/day, i.p.) treatment was started 24h before the first administration of VCM and continued for 8 days. After the 14th VCM injection, the animals were placed in metabolic cages to collect urine samples. All the rats were sacrificed by decapitation, blood samples were taken in tubes and kidneys were excised immediately. Blood urea nitrogen (BUN) and plasma creatinine, and urinary N-acetyl-beta-d-glucosaminidase (NAG, a marker of renal tubular injury) were used as markers of VCM-induced renal injury in rats. Light microscopy was used to evaluate semi-quantitative analysis of the kidney sections. Poly(ADP-ribose) (PAR, the product of activated PARP) and PARP-1 expressions in renal tissues were demonstrated by immunohistochemistry and Western blot. VCM administration increased BUN levels from 8.07+/-0.75 mg/dL to 53.87+/-10.11 mg/dL. The plasma creatinine levels were 0.8+/-0.04 mg/dL and 3.38+/-0.51 mg/dL for the control and VCM-treated groups, respectively. Also, urinary excretion of NAG was increased after VCM injection. Besides, there was a significant dilatation of the renal tubules, eosinophilic casts within some tubules, desquamation and vacuolization of renal tubule epithelium, and interstitial tissue inflammation in VCM-treated rats. In VCM-treated rats, both PAR and PARP-1 expressions were increased in renal tubular cells. ISO treatment attenuated VCM-induced renal injury, as indicated by BUN and plasma creatinine levels, urinary NAG excretion, and renal histology. PARP inhibitor treatment also decreased PAR and PARP-1 protein expressions similar to that of controls. Herewith, the overactivation of the PARP pathway may have a role in VCM-induced renal impairment and pharmacological inhibition of this pathway might be an effective intervention to prevent VCM-induced acute renal injury.

[Design and validation of a dosing algorithm for vancomycin in premature neonates]

INTRODUCTION

Inappropriate use of vancomycin contributes to the development of resistant bacteria and jeopardizes the safety and effectiveness of treatment. The aim of this article was to design and validate an empirical dosing algorithm for vancomycin in premature neonates according to their population-based pharmacokinetic characteristics.

PATIENTS AND METHODS

We performed a retrospective analysis of 129 serum samples from a cohort of 53 neonates. Homogeneous population groups were identified both from their individual pharmacokinetic parameters and from their biometric characteristics. The design of the dosing algorithm was based on simulation of the serum vancomycin concentration that would be reached with several different doses. The algorithm was validated in another cohort of 30 neonates and 108 serum samples.

RESULTS

Introduction of the algorithm significantly increased the percentage initial values obtained with correct minimum and maximum concentrations in the first monitoring round (p<0.05). The mean number of serum samples obtained per patient for treatment monitoring was significantly reduced (3.6+/-2 vs. 4.9+/-3).

CONCLUSIONS

The implantation of the dosing algorithm for vancomycin in premature neonates increased the efficiency of treatment, reduced monitoring requirements, and optimized serum vancomycin concentrations from the start of treatment.

Novel evidence suggesting an anti-oxidant property for erythropoietin on vancomycin-induced nephrotoxicity in a rat model

1. The aim of the present study was to investigate the role of oxidative stress in renal injury and to determine whether erythropoietin (EPO) acts as an anti-oxidant in vancomycin (VCM)-induced renal impairment. 2. Twenty-four rats were divided into three groups as follows: (i) control (Group 1); (ii) VCM treated (Group 2); and (iii) VCM + EPO treated (Group 3). Vancomycin (200 mg/kg, i.p.) was administered to Groups 2 and 3 for 7 days. Erythropoietin (150 IU/kg, i.p.) treatment was started 24 h before VCM and lasted for 7 days. On Day 8, renal tissues were excised and blood samples were collected. Serum creatinine and blood urea nitrogen were measured, along with renal malondialdehyde (MDA) levels, superoxide dismutase (SOD) and catalase (CAT) activity and tissue VCM levels. The kidneys were examined for any histopathological changes. 3. Renal MDA levels were found to be increased, whereas SOD and CAT activity was decreased, in the VCM-treated group compared with the control group. There was a marked decrease in MDA levels and an increase in SOD activity, but not CAT activity, after VCM + EPO treatment. Marked histopathological alterations, including interstitial oedema, tubular dilatation, tubular epithelial cell desquamation and vacuolization, were observed in VCM-treated rats. Histopathological changes were significantly improved after EPO administration. 4. In conclusion, the present data suggest that oxidative stress plays an important role in VCM-induced nephrotoxicity. Erythropoietin seems to act as an anti-oxidant, diminishing the toxic oxidative effects of VCM on renal tissues.

Vancomycin pharmacokinetics in preterm infants

OBJECTIVE

[corrected] The objective of the present study was to evaluate the kinetic disposition of vancomycin in preterm infants with emphasis on the apparent volume of distribution, biological half-life, and total body clearance as well as whether their variations cause significant modification of the trough plasma concentration of the drug, depending on the postconceptional age (PCA) and the postnatal age (PNA).

MATERIAL AND METHOD

Twenty-five selected patients were distributed into 2 groups which differed significantly in terms of mean PCA (31.2-32.3 weeks in group 1, n = 13; 33.5-34.1 weeks in group 2, n = 12: CI95%, P < .001) and PNA (group 1, 12.0-18.5 days; group 2, 18.0-34.0 days, CI95%, P < .05). The parents were informed and signed a written consent for participation of the infants in the protocol that had been previously approved by the Ethics Committee of the hospital.

RESULTS

Apparent volume of distribution was significantly increased in group 1 compared with patients of group 2 (0.85 vs. 0.56 L/kg, respectively; P = .01,). Additionally multiple linear regression revealed a good linear correlation (r = 0.85) of trough plasma concentration of vancomycin with the apparent volume of distribution and also with the biological half-life in patients of group 1, while a good correlation (r = 0.91) was obtained for the trough plasma concentration with total body clearance in infants of group 2. The influence of these kinetic parameters on the trough concentration of vancomycin in preterm infants seems to vary according to PCA and PNA.

CONCLUSION

In conclusion, the trough plasma concentration of vancomycin depends on the pharmacokinetics, and multiple linear correlation indicates that it varies according to the postconceptional and postnatal age of preterm infants.

Antimicrobial therapy and local toxicity of intraventricular administration of vancomycin in a neonate with ventriculitis

Infection is the most common complication and cause of failure of cerebrospinal fluid (CSF) shunt devices used to control hydrocephalus. A male newborn was admitted for treatment of congenital occlusive hydrocephalus by means of a ventriculo-peritoneal shunt. A day later, the skin area around the site of insertion of ventriculo-peritoneal catheter was red and edematous. Intravenous ceftazidime and vancomycin were initiated. The shunt was removed but the external ventricular drain was preserved. Blood and CSF cultures showed Enterococcus faecalis sensitive to vancomycin, ciprofloxacin and gentamicin, but resistant to ampicillin. Intraventricular administration of vancomycin 10 mg/24 h was initiated through the external ventricular drain. Before the first dose of vancomycin intraventricularly, CSF levels were 19 mg/dL as a result of administration. On the third day of intraventricular dosing, vancomycin levels in CSF reached 388 mg/dL and protein levels were 1160 mg/dL. On the fifth day of intraventricular treatment the patient had clinically improved and was bacteriologically cured. However, in CSF, protein levels were 3300 mg/dL and vancomycin levels 201 mg/dL. In an attempt to prevent high and potentially toxic levels in CSF, the intraventricular dose of vancomycin should be individualized according to clinical response, bacteriological cultures, vancomycin levels in CSF, and surrogate markers of neurotoxicity, that is, eosinophilia and high protein levels in CSF.

Evaluation of Bayesian predictability of vancomycin concentration using population pharmacokinetic parameters in pediatric patients

The objective of this study was to evaluate the Bayesian predictability of vancomycin (VCM) pharmacokinetics in Japanese pediatric patients using one-compartment population pharmacokinetic (PPK) parameters, which we reported previously. The validity of the PPK model was evaluated by bootstrap method and cross validation method, and the Bayesian predictive performance was examined. The predictive performance of the PPK model for premature patients was also examined. The cross validation method showed the predictability to be acceptable for practical use, especially for predicting trough concentration using other trough data. However, for the external premature patient data, this PPK model did not seem to be adequate. A theoretical approach using a simulation technique was also examined to evaluate the predictive performance. The results suggested that the predictability at the peak was not necessarily good at all sampling times and the predictability at the trough was better when a later time point was used. The optimal sampling time for prediction of VCM concentration in pediatric patients is discussed.

A retrospective drug utilization evaluation of vancomycin usage in paediatric patients

OBJECTIVE

To evaluate the appropriateness of use of vancomycin in paediatric patients at KK Women's and Children's Hospital, the major paediatric hospital in Singapore to identify potential problems in prescribing practices that may necessitate intervention to optimize vancomycin usage.

METHODS

A retrospective drug utilization evaluation was performed for paediatric patients who received intravenous vancomycin from 1 June 1998 to 31 June 1999. The outcome measures were consistency of vancomycin indication with recommended guidelines, dosing regimens, microbiological data, monitoring of serum drug levels, renal function, clinical outcomes and adverse drug reactions (ADRs).

RESULTS

A total of 96 cases was available for evaluation. Sixty-two (64.6%) courses of vancomycin were consistent with guidelines for indication of therapy. Eighty-six (89.6%) of the dosing regimen were consistent. All infusion times that were recorded (56.3%) were consistent with criteria. Of the patients treated with vancomycin for more than 1 day, peak and/or trough serum vancomycin levels were ordered for 70 cases. Of the 56 cases with paired levels ordered, 46 cases had at least one level that fell outside the therapeutic range. Nineteen (19.8%) cases of ADRs were documented. Fifty-eight (60.4%) cases received concurrent nephrotoxic drugs. However, a substantial portion of vancomycin courses were apparently not prescribed for appropriate indications, and there was poor recording of vancomycin administration information and sampling time.

CONCLUSION

The majority of dosing regimens of vancomycin was consistent with guideline criteria. The most evident problem was the sub-optimal use of the monitoring of vancomycin serum levels. The information derived from this study may be used as a for further study and for the development of strategies for optimize vancomycin usage.

Therapeutic vancomycin monitoring in children with hydrocephalus during treatment of shunt infections

BACKGROUND

The successful treatment of shunt infections in children with hydrocephalus is still an important problem. Diagnosis of shunt colonization is often very difficult. To treat serious central nervous system (CNS) infections, intraventricular therapy with antibiotics is necessary to reach adequate cerebrospinal fluid (CSF) concentrations and eradicate the infection. For optimal management of shunt infections the concentration of administered antibiotics in CSF should be measured. The antibiotic dosing could be modified in the individual patient after pharmacokinetic studies.

METHODS

In our studies, vancomycin was applied to 10 children with hydrocephalus (including 6 with a myelomeningocele) for therapeutic purposes in shunt infections. The drug was administered IV and/or intraventricularly. During treatment the concentration of vancomycin in CSF was determined by fluorescence polarization immunoassay (FPIA) method.

RESULTS

Considerable differences in vancomycin concentrations after the same intraventricular antibiotic administration were observed depending on the patient. The vancomycin levels determined at study state were often much higher than the therapeutic recommended range, and the biologic half-life period (T(1/2)) of vancomycin in cerebrospinal fluid after intraventricular administration was prolonged.

CONCLUSIONS

The results of our studies give information about the pharmacokinetics of vancomycin in CSF in a group of children with hydrocephalus after intraventricular administration of the drug. In our investigation, the administration of doses smaller than 5 mg/24 hours is appropriate when the removed volume of CSF will be 20 to 30 mL/24 hours.

Direct medical costs associated with using vancomycin in methicillin-resistant Staphylococcus aureus infections: an economic model

OBJECTIVES

To quantify the direct medical costs associated with using vancomycin, as inpatient treatment, in methicillin-resistant Staphylococcus aureus infections, in four clinical indications: complicated skin and soft tissue infections (SSTI), bacteremia, infective endocarditis (IE), and hospital-acquired pneumonia (HAP).

RESEARCH DESIGN AND METHODS

A decision-analytic model was constructed to evaluate the cost of administering intravenous vancomycin. Cost inputs included hospitalization, drug procurement, materials, preparation and administration, renal function and drug monitoring, treating adverse events, and treatment failure. Probabilities and lengths of stay and treatment were obtained from the literature, an antimicrobial therapy database and clinical expert opinion. Univariate and multivariate sensitivity analyses were conducted to confirm the robustness of the baseline scenario.

MAIN OUTCOME MEASURES

The cost of using vancomycin in the four indications, including and excluding hospital cost.

RESULTS

Whereas the drug acquisition price of vancomycin 1g is US dollars 9.01 per dose, when all costs associated with using vancomycin were included, the cost per dose rose to US dollars 29-US dollars 43 per patient. Total costs per patient receiving multiple doses in a single course of treatment, excluding hospital room costs, were for SSTI, bacteremia, IE, and HAP,US dollars 779, US dollars 749, US dollars 2261, and US dollars 768, respectively. Total costs, including hospital length of stay, were for SSTI US dollars 23616, bacteremia US dollars 26446, IE US dollars 48925, and HAP US dollars 22493. In univariate analyses varying per diem hospital costs and length of stay had the greatest impact. Results of the multivariate analysis were comparable to the costs in the baseline scenario for all indications.

CONCLUSIONS

This analysis highlights the importance of capturing all costs associated with using a drug and not simply focusing on drug acquisition cost. Future economic analyses should identify and account for the key cost burdens of a particular treatment to calculate its true cost.

Vancomycin

This review describes the use of vancomycin in neonates over the last three decades. Given the relation of late-onset neonatal septicaemia to outcome and the increase in coagulase-negative staphylococcal infection as causative organism, vancomycin remains an important antibacterial in the neonatal intensive care unit. The pharmacokinetic behaviour of vancomycin in neonates can be adequately described by a one- or two-compartment model and is mainly determined by postconceptional age and renal function. In neonates, a patent ductus arteriosus as well as treatment with indomethacin or extracorporeal membrane oxygenation (ECMO) leads to an increase in volume of distribution and a decrease in clearance. Microbiological studies in vitro have shown that an increase in vancomycin concentrations above the minimum inhibitory concentration does not result in more effective killing. The microbiological and clinical efficacy of vancomycin in neonates has only been studied explicitly in a restricted number of patients. There are no definitive data relating serum concentrations to effect in this patient group. Vancomycin-related nephrotoxicity and ototoxicity in neonates is rare, and no clear relation to serum concentrations has been demonstrated. Based on the pharmacokinetic profile of vancomycin in neonates, several administration regimens have been constructed. Recent guidelines have suggested that dosage can be independent of gestational age or postconceptional age in neonates without renal failure. In patients with renal failure, therapy can be adequately tailored by using a regimen based on serum creatinine. The usefulness of routine monitoring of peak serum concentrations is doubtful based on the current literature. Recent research demonstrates a shift towards taking only routine trough serum concentrations in order to optimise efficacy. Patients with renal failure and other special subpopulations, such as patients exposed to ECMO or indomethacin, need to be monitored more closely.

Aminoglycoside and vancomycin serum concentration monitoring and mortality due to neonatal sepsis in Saudi Arabia

OBJECTIVE

To assess the effectiveness of monitoring of serum concentration of aminoglycosides in neonates.

METHOD

A retrospective evaluation of serum concentration monitoring of aminoglycosides (gentamicin and amikacin) and vancomycin in neonates treated for sepsis in a maternity and children hospital in Jeddah, Saudi Arabia, over the period 1998-2000.

RESULTS

The total number of requests for monitoring increased sixfold in 1999 and 12-fold in 2000 relative to 1998. For aminoglycosides, the incidence of both subtherapeutic peak and toxic trough serum levels decreased significantly (P < 0.05) in 1999 and 2000 compared with 1998. Furthermore, the rate of neonatal mortality caused by sepsis showed reduction in both 1999 (34%) and 2000 (35%) in comparison with 1998 (45%). Vancomycin trough (effective) concentration monitoring revealed no change in the incidence (30%) of levels at subtherapeutic values (<5.0 microg/mL) between the compared years. Furthermore, the rate of toxic levels (>10 microg/mL) increased in both 1999 (31%) and 2000 (39%) relative to 1998 (25%).

CONCLUSION

Therapeutic drug monitoring of vancomycin needs re-evaluation in the hospital to explain why existing methods are ineffective.

Antibiotics and breast-feeding: a critical review of the literature

Continuous breast-feeding, an integral component of the postpartum period, is often threatened upon maternal initiation of antibiotics. The real risk of antibiotic use while breast-feeding must be carefully analysed with regard to all the variables that influence the extent of antibiotic distribution into breast milk, including breast milk composition, physicochemical properties of the antibiotic (molecular weight, lipid solubility, pH, protein binding), length of feeding, and maternal disposition. In addition, infant disposition, including ability to absorb, metabolize, eliminate, and tolerate any amounts of antibiotic, must also be considered prior to maternal administration of antibiotic. The milk to plasma (M/P) ratio is a frequently quoted parameter used to predict drug distribution into breast milk. However, its utility is questionable and often fraught with misinterpretation. An alternative approach when the amount of antibiotic concentration in breast milk is known (through clinical trials) is to calculate an estimated or expected infant drug exposure factoring in known/expected milk consumption, drug concentration and bioavailability. In this review, the following antibiotic classes and current literature regarding their distribution into breast milk are critically reviewed: beta-lactam antibiotics, fluoroquinolones, sulfonamides, macrolides, aminoglycosides, tetracyclines, nitrofurantoin, metronidazole, vancomycin, clindamycin and chloramphenicol. In the majority of instances, these antibiotics do not distribute into breast milk in sufficient concentrations to be of any clinical consequence in the breast-feeding infant.