Simple approach to improving vancomycin dosing in intensive care: a standardised loading dose results in earlier therapeutic levels

Impact of Limiting Vancomycin Loading Doses in Patients With Methicillin-resistant Staphylococcus aureus Infections After Hospital Protocol Revision

Background: Vancomycin loading doses are commonly used to quickly attain target serum concentrations; however, data supporting their effect on clinical patient outcomes is limited. In April 2020, our institution revised our pharmacist-driven vancomycin dosing protocol to reserve loading doses for hemodynamically unstable patients with suspected serious methicillin-resistant Staphylococcus aureus (MRSA) infections. Prior to the protocol update, all patients treated with vancomycin at our institution received a weight-based loading dose. The purpose of this study is to assess clinical efficacy and safety outcomes related to the use of vancomycin loading doses. Methods: A retrospective, quasi-experimental study was performed to compare clinical outcomes in adult patients treated with vancomycin for laboratory-confirmed MRSA infections. Patients who received vancomycin therapy prior to our institution's vancomycin dosing protocol revisions (pre-intervention) were compared to patients who received vancomycin after the revisions (post-intervention). The primary outcome was all-cause, inpatient mortality. Secondary outcomes included persistent signs and symptoms of infection ≥5 days after vancomycin initiation, switch to alternative anti-MRSA therapy, and nephrotoxicity. Results: A total of 122 patients (63 pre-intervention patients and 59 post-intervention patients) were included. Receipt of a vancomycin loading dose did not impact the rate of inpatient mortality (4.76%vs 6.78%; OR 1.46, 95% CI [0.31, 6.79]). All secondary outcomes were similar between the two groups, including persistent signs and symptoms of infection, switch to alternative anti-MRSA therapy, and nephrotoxicity. Conclusions: Routine use of vancomycin loading doses is not associated with improved outcomes in hemodynamically stable patients with MRSA infections.

Vancomycin dosing in high-intensity continuous renal replacement therapy: A retrospective cohort study

INTRODUCTION

An inverse relationship exists between vancomycin serum concentrations and the intensity of continuous renal replacement therapy (CRRT), reflected through the dialysate flow rate (DFR). There remains a lack of evidence to guide initial vancomycin dosing in the setting of high-intensity CRRT (i.e., DFR >30 mL/kg/h). Additionally, recommendations for pharmacokinetic monitoring of vancomycin have transitioned from a trough-based to area under the curve (AUC)-based dosing strategy to optimize efficacy and safety. Therefore, an improved understanding of the impact of CRRT intensity on AUC/MIC (minimum inhibitory concentration) has the potential to enhance vancomycin dosing in this patient population.

OBJECTIVES

The goal of this study is to evaluate current vancomycin dosing strategies and achievement of pharmacokinetic targets in patients on high-intensity CRRT.

METHODS

This was a single-center, retrospective cohort study of adult critically ill patients admitted to Houston Methodist Hospital between May 2019 and October 2021 and received vancomycin therapy while on high-intensity CRRT. High-intensity CRRT was defined by a DFR that was both ≥3 L/h and >30 mL/kg/h. Depending on the initial vancomycin dosing strategy, patients were stratified into either the traditional (15 mg/kg/day) or enhanced (≥15 mg/kg/day) dosing group. The primary outcome was the percent of patients who attained steady-state AUC24 /MIC ≥400 mg*h/L at the first obtained vancomycin level in the enhanced group compared with the traditional group.

RESULTS

A total of 125 patients were included in the final analysis, 56 in the traditional and 69 in the enhanced dosing group. The primary end point occurred in 74% and 54% of patients in the enhanced and traditional dosing groups, respectively (p = 0.029). Therapeutic vancomycin trough levels (10-20 μg/mL) were more commonly achieved in the enhanced dosing group compared with the traditional dosing group (66.7% vs. 45%, p = 0.013). As DFR rose, increasingly higher doses of vancomycin, up to 27 mg/kg/day, were required to achieve the therapeutic targets.

CONCLUSION

This is the first study to evaluate the influence of variable CRRT intensities on vancomycin AUC/MIC. Our findings suggest that vancomycin doses of ≥15 mg/kg/day are needed to achieve early therapeutic targets in patients on high-intensity CRRT.

Impact of Vancomycin Loading Doses and Dose Escalation on Glomerular Function and Kidney Injury Biomarkers in a Translational Rat Model

Vancomycin-induced kidney injury is common, and outcomes in humans are well predicted by animal models. This study employed our translational rat model to investigate temporal changes in the glomerular filtration rate (GFR) and correlations with kidney injury biomarkers related to various vancomycin dosing strategies. First, Sprague-Dawley rats received allometrically scaled loading doses or standard doses. Rats that received a loading dose had low GFRs and increased urinary injury biomarkers (kidney injury molecule 1 [KIM-1] and clusterin) that persisted through day 2 compared to those that did not receive a loading dose. Second, we compared low and high allometrically scaled vancomycin doses to a positive acute kidney injury control of high-dose folic acid. Rats in both the low- and high-dose vancomycin groups had higher GFRs on all dosing days than the positive-control group. When the two vancomycin groups were compared, rats that received the low dose had significantly higher GFRs on days 1, 2, and 4. Compared to low-dose vancomycin, the KIM-1 was elevated among rats in the high-dose group on dosing day 3. The GFR correlated most closely with the urinary injury biomarker KIM-1 on all experimental days. Vancomycin loading doses were associated with significant losses of kidney function and elevations of urinary injury biomarkers. In our translational rat model, both the degree of kidney function decline and urinary biomarker increases corresponded to the magnitude of the vancomycin dose (i.e., a higher dose resulted in worse outcomes).

VANCOmycin dose adjustments comparing trough levels to the ratio of the area under de curve to the minimum inhibitory concentration method using a BAYESian approach: A feasibility study

WHAT IS KNOWN AND OBJECTIVE?: The latest published guidelines advocate for the area under the concentration-time curve to minimal inhibitory concentration (AUC_0-24h /MIC) estimated with bayesian calculations. This recommended pharmacokinetic monitoring transition is not based on randomized controlled prospective data. METHODS: In this open-label feasibility RCT, patients were assigned to have their vancomycin dosing adjusted based on bayesian-guided AUC_0-24h /MIC or trough levels. Primary outcomes were consent rate, number of patients recruited per month, compliance with blood sampling schedule and compliance with bayesian software recommendations. Secondary outcomes focused on target attainment, safety and operational impacts. RESULTS AND DISCUSSION: Forty-five patients underwent randomization (23 bayesian, 22 trough). Consent rate was 37,5% for an average of 9.8 patients recruited per month meeting pre-specified objectives of 30% (p = 0.073) and 10 (p = 0.74) respectively. A 74.8% compliance with blood sampling schedule was below the pre-specified objective of 80% (p = 0.038). There was no statistically significant difference between the 83.7% compliance with bayesian software recommendations and the pre-specified objective of 90% (p = 0.21). Although exploratory, key clinical results were significant increases in the bayesian group for proportion of levels at target (RR 1.32; 95% CI 1.01-1.72; P = 0.038), number of blood samplings for patients (p = 0.036) and pharmacists' time spent on monitoring (p < 0.0001). A tendency towards a reduced incidence of nephrotoxicity in the Bayesian group was observed (RR 0.57; 95% CI 0.16-2.12; p = 0.46). WHAT IS NEW AND CONCLUSIONS?: This trial demonstrates that it would be feasible to conduct a properly sized RCT comparing vancomycin Bayesian-guided AUC_0-24h /MIC to trough level monitoring. Although exploratory, this trial also showed a tendency towards reduced incidence of nephrotoxicity and an increased proportion of dosages at therapeutic targets with Bayesian monitoring.

A Systematic Review on Clinical Safety and Efficacy of Vancomycin Loading Dose in Critically Ill Patients

Background: The clinical significance of utilizing a vancomycin loading dose in critically ill patients remains unclear. Objective: The main aim of this systematic review is to evaluate the clinical safety and efficacy of the vancomycin loading dose in critically ill patients. Methods: We performed a systematic review using PRISMA guidelines. PubMed, the Web of Science, MEDLINE, Scopus, Google Scholar, the Saudi Digital Library and other databases were searched. Studies that reported clinical outcomes among patients receiving the vancomycin LD were considered eligible. Data for this study were collected using PubMed, the Web of Science, MEDLINE, Scopus, Google Scholar and the Saudi Digital Library using the following terms: “vancomycin”, “safety”, “efficacy” and “loading dose” combined with the Boolean operator “AND” or “OR”. Results: A total of 17 articles, including 2 RCTs, 11 retrospective cohorts and 4 other studies, met the inclusion/exclusion criteria out of a total 1189 studies. Patients had different clinical characteristics representing a heterogenous group, including patients in critical condition, with renal impairment, sepsis, MRSA infection and hospitalized patients for hemodialysis or in the emergency department. Conclusions: The study shows that the target therapeutic level is achieved more easily among patients receiving a weight-based LD as compared to patients received the usual dose without an increased risk of new-onset adverse drug reactions.

Target serum concentration of vancomycin may be reached earlier with a loading dose

BACKGROUND

Vancomycin treatment failure against vancomycin-susceptible gram-positive cocci is not rare in the intensive care unit (ICU). One of the reasons for this is the substandard drug trough concentration. We aimed to examine the hypothesis that the target serum concentration could be reached earlier with a loading dose of vancomycin.

METHODS

This retrospective cohort study was conducted at our ICU between June 2018 and June 2020 and involved patients who were suspected of having, or confirmed to have, gram-positive cocci infection and treated with vancomycin. One group of the patients was administered a loading dose of vancomycin (loading group) and compared with the group that did not receive a loading dose (control group). The baseline characteristics, vancomycin serum concentrations, and clinical outcomes were collected and analyzed.

RESULTS

Fifty-five patients were finally included, of which 29 received a loading dose of vancomycin. The serum concentration of vancomycin before the second dose was significantly higher for the loading group than for the control group (10.3 ± 6.1 mg/L vs. 5.7 ± 4.4 mg/L, P = 0.002). The results for both groups were similar before the fifth dose (12.4 ± 7.3 mg/L vs. 10.3 ± 6.3 mg/L in the loading and the control groups, respectively; P = 0.251). The 28-day mortality was lower for the loading group than for the control group (6.7% vs. 34.6% in the loading and control groups, respectively; P = 0.026). No significant differences were observed in serum creatinine (Cr) concentrations of the two groups.

CONCLUSION

With the loading dose of vancomycin, the target serum concentration of vancomycin may be reached earlier without increasing the risk of acute kidney injury.

TRIAL REGISTRATION

https://www.chictr.org.cn; ChiCTR2000035369.

Impact of a vancomycin loading dose on the achievement of target vancomycin exposure in the first 24 h and on the accompanying risk of nephrotoxicity in critically ill patients

Background

The advocated pharmacokinetic/pharmacodynamic (PK/PD) target for vancomycin, AUC/MIC ≥ 400 mg·h/L, may not be reached with a conventional fixed starting dose of 1000 mg in critically ill patients, but increasing the dose may cause nephrotoxicity.

Objectives

To evaluate the effect of a weight-based loading dose of 25 mg/kg vancomycin on PK/PD target attainment in the first 24 h (AUC_0–24) in critically ill patients and to evaluate whether this increases the risk of acute kidney injury (AKI).

Patients and methods

A prospective observational before/after study was performed in ICU patients, comparing the percentage of vancomycin courses with AUC_0–24 ≥ 400 mg·h/L and the incidence of AKI, defined as worsening of the risk, injury, failure, loss of kidney function and end-stage kidney disease (RIFLE) score. The conventional dose group received 1000 mg of vancomycin as initial dose; the loading dose group received a weight-based loading dose of 25 mg/kg. A population PK model developed using non-linear mixed-effects modelling was used to estimate AUC_0–24 in all patients.

Results

One hundred and four courses from 82 patients were included. With a loading dose, the percentage of courses achieving AUC_0–24 ≥ 400 mg·h/L increased significantly from 53.8% to 88.0% (P = 0.0006). The percentage of patients with new-onset AKI was not significantly higher when receiving a 25 mg/kg loading dose (28.6% versus 37.8%; P = 0.48). However, the risk of AKI was significantly higher in patients achieving AUC_0–24 > 400 mg·h/L compared with patients achieving AUC < 400 mg·h/L (39.0% versus 14.8%; P = 0.031).

Conclusions

A weight-based loading dose of 25 mg/kg vancomycin led to significantly more patients achieving AUC_0–24 ≥ 400 mg·h/L without increased risk of AKI. However, some harm cannot be ruled out since higher exposure was associated with increased risk of AKI.

Evidence-based Guideline for Therapeutic Drug Monitoring of Vancomycin: 2020 Update by the Division of Therapeutic Drug Monitoring, Chinese Pharmacological Society

BACKGROUND

Clinical practice guidelines or recommendations often require timely and regular updating as new evidence emerges, because this can alter the risk-benefit trade-off. The scientific process of developing and updating guidelines accompanied by adequate implementation can improve outcomes. To promote better management of patients receiving vancomycin therapy, we updated the guideline for the therapeutic drug monitoring (TDM) of vancomycin published in 2015.

METHODS

Our updated recommendations complied with standards for developing trustworthy guidelines, including timeliness and rigor of the updating process, as well as the use of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. We also followed the methodology handbook published by the National Institute for Health and Clinical Excellence and the Spanish National Health System.

RESULTS

We partially updated the 2015 guideline. Apart from adults, the updated guideline also focuses on pediatric patients and neonates requiring intravenous vancomycin therapy. The guideline recommendations involve a broadened range of patients requiring TDM, modified index of TDM (both 24-hour area under the curve and trough concentration), addition regarding the necessity and timing of repeated TDM, and initial dose for specific subpopulations. Overall, 1 recommendation was deleted and 3 recommendations were modified. Eleven new recommendations were added, and no recommendation was made for 2 clinical questions.

CONCLUSIONS

We updated an evidence-based guideline regarding the TDM of vancomycin using a rigorous and multidisciplinary approach. The updated guideline provides more comprehensive recommendations to inform rational and optimized vancomycin use and is thus of greater applicability.

Efficacy and safety of vancomycin loading doses in critically ill patients with methicillin-resistant Staphylococcus aureus infection

Background

While vancomycin loading doses may facilitate earlier pharmacokinetic-pharmacodynamic target attainment, the impact of loading doses on clinical outcomes remains understudied. Critically ill patients are at highest risk of morbidity and mortality from methicillin resistant Staphylococcus aureus (MRSA) infection and hypothesized to most likely benefit from a loading dose. We sought to determine the association between receipt of a vancomycin loading dose and clinical outcomes in a cohort of critically ill adults.

Methods

Four hundred and forty-nine critically ill patients with MRSA cultures isolated from blood or respiratory specimens were eligible for the study. Cohorts were established by receipt of a loading dose (⩾20 mg/kg actual body weight) or not. The primary outcome was clinical failure, a composite outcome of death within 30 days of first MRSA culture, blood cultures positive ⩾7 days, white blood cell count up to 5 days from vancomycin initiation, temperature up to 5 days from vancomycin initiation, or substitution (or addition) of another MRSA agent.

Results

There was no difference in the percentage of patients experiencing clinical failure between the loading dose and no loading dose groups (74.8% versus 72.8%; p = 0.698). Secondary outcomes were also similar between groups, including mortality and acute kidney injury, as was subgroup analysis based on site of infection. Exploratory analyses, including assessment of loading dose based on quartiles and a multivariable logistic regression model showed no differences.

Conclusion

Use of vancomycin loading doses was not associated with improved clinical outcomes in critically ill patients with MRSA infection.

Effect of vancomycin loading dose on clinical outcome in critically ill patients with methicillin-resistant Staphylococcus aureus pneumonia

Background

Vancomycin is the treatment of choice for serious methicillin-resistant Staphylococcus aureus (MRSA) infections. Current guidelines recommend giving an initial loading dose (LD) of 25–30 mg/kg to rapidly increase the serum concentration. However, high-quality evidence for the clinical benefit of LD is lacking. Herein, we aim to examine the association between vancomycin LD and clinical outcome.

Methods

A retrospective cohort study was conducted on adult patients treated for MRSA pneumonia with vancomycin in medical intensive care units from April 2016 to August 2018. MRSA pneumonia was defined by the Centers for Disease Control and National Healthcare Safety Network definition. The primary outcome was the clinical cure of pneumonia. Secondary outcome measures included time to pharmacokinetic (PK) target attainment, microbiological cure, acute kidney injury, and all-cause mortality.

Results

A total of 81 patients were included; of these 22 (27.2%) received LD. The mean initial dose was significantly higher in the LD group. Clinical cure was similar in both groups (68.2% vs. 66.1% in the LD and non-LD groups, respectively; P=0.860). No significant difference was observed in the microbiological cure, all-cause mortality, and incidence of acute kidney injury. Furthermore, no difference was observed in terms of time to PK target attainment (69.2 vs. 63.4 h in the LD and non-LD groups, respectively; P=0.624). Vancomycin minimum inhibitory concentration of <2 mg/L was identified as an independent predictive factor for clinical cure in multivariable analysis, whereas vancomycin LD was not.

Conclusions

Initial LD is not associated with better clinical outcome or rapid pharmacological target attainment in critically ill patients with MRSA pneumonia. Further studies are warranted to provide better evidence for this widely recommended practice.

First-Dose Vancomycin Pharmacokinetics Versus Empiric Dosing on Area-Under-the-Curve Target Attainment in Critically Ill Patients

BACKGROUND

Early attainment of target area under the curve (AUC) to minimum inhibitory concentration (MIC) ratios have been associated with clinical success, as well as lower incidence of acute kidney injury (AKI), in patients receiving vancomycin for methicillin-resistant Staphylococcus aureus (MRSA). Critically ill patients are particularly vulnerable to poor outcomes from infection and face multiple risk factors for AKI, thus early precision dosing of vancomycin is vital in this population. We hypothesized that a personalized dosing approach, using vancomycin levels obtained after the first dose to guide further dosing, would be superior to empiric dosing in terms of AUC target attainment assessed at steady state (SS).

METHODS

A retrospective cohort study of 66 critically ill adult patients admitted to the medical intensive care unit without AKI and receiving vancomycin with at least two SS concentrations obtained for AUC calculation was performed. Patients were separated into cohorts based on whether they had two concentrations assessed after the first dose of vancomycin and were subsequently dosed based on personalized pharmacokinetic calculations (first-dose kinetics) or whether they were empirically dosed using population estimates. The primary outcome was AUC target attainment (400-600 mg hour/L) at SS.

RESULTS

Compared with patients receiving empiric dosing by population estimates, using first-dose kinetics to guide subsequent dosing resulted in significantly greater AUC target attainment at SS (58.6% first-dose vs 32.4% empiric; p=0.033). Patients dosed empirically yielded more variable AUC values across a wide range compared with the first-dose kinetics group (coefficient of variation 40.7% empiric vs 26.1% first-dose). There was no difference in AKI up to 48 hours after SS concentrations between the two dosing schemes.

CONCLUSIONS

A dosing strategy using two vancomycin serum concentrations after the first dose and calculating personalized pharmacokinetic parameters to guide subsequent dosing is associated with greater AUC target attainment at SS compared with empiric dosing of vancomycin in critically ill adults with relatively stable renal function.

Vancomycin in ICU Patients with Gram-Positive Infections: Initial Trough Levels and Mortality

Background

Vancomycin is one of the most common therapeutic agents for treating gram-positive infections, particularly in critically ill patients. The aim of this study was to identify factors associated with initial therapeutic vancomycin trough levels and mortality in a tertiary-care intensive care unit (ICU).

Methods

This retrospective study evaluated 301 adult ICU patients admitted to King Abdulaziz Medical City in Riyadh between October 1, 2017 and December 31, 2018 with confirmed gram-positive infections and received intravenous vancomycin. Vancomycin trough levels of 15–20 mg/L for severe infections and 10–15 mg/L for less severe infections were considered therapeutic.

Results

The patients were relatively older with a mean age of 60 (SD ±20) years. Initial vancomycin trough levels were therapeutic in 168 (55.8%). Factors associated with initial therapeutic vancomycin trough levels were female gender (adjusted odds ratio [aOR]=2.575), older age (aOR=1.024), receiving a loading dose (aOR=2.445), having bacteremia (aOR=2.061), and high platelet count (aOR=1.003). On the other hand, the increase of estimated glomerular filtration rate (eGFR) (aOR=0.993) and albumin levels (aOR=0.944) were associated with lower odds of initial therapeutic vancomycin trough levels. Factors associated with higher mortality were female gender (adjusted hazard ratio [aHR]=2.630), increased body weight (aHR=1.021), cancer (aHR=3.451), and high APACHE II score (aHR=1.068).

Conclusion

The study identified several factors associated with achieving initial therapeutic vancomycin trough levels (i.e. older age, female gender, receiving a loading dose, bacteremia, high platelets count, low eGFR and albumin level). These factors should be considered in the dosing of vancomycin in critically ill patients with gram-positive infections.

Effect of Vancomycin Loading Doses on the Attainment of Target Trough Concentrations in Hospitalized Children

OBJECTIVE

Subtherapeutic vancomycin trough concentrations are common in children and may be associated with suboptimal therapeutic response. Our objective was to determine if vancomycin loading doses safely increase the frequency of target trough attainment in hospitalized children.

METHODS

Patients (≥6 months and <18-years-old) who received a vancomycin loading dose between February 1, 2018, and January 30, 2019, were retrospectively enrolled. These patients were compared to a convenience cohort of patients hospitalized between January 1, 2015, and December 31, 2015, who received vancomycin without a loading dose. Target trough concentrations were defined as >15 mg/dL for invasive infections and >10 mg/dL for non-invasive infections.

RESULTS

A total of 151 patients were enrolled, with 77 in the control arm and 74 in the loading dose arm. There was no significant difference in the frequency of comorbidities or need for intensive care unit admission between the two arms. Those receiving a vancomycin loading dose were older (mean age 9.1 vs 5.2 years, p < 0.0001). Patients given a loading dose achieved higher mean initial trough values (13.0 mg/dL vs 9.2 mg/dL, p < 0.0001), were more likely to have an initial trough at or above target (37.0% vs 10.4%, p = 0.0001), were more likely to reach target trough values at any point during therapy (52.1% vs 32.9%, p = 0.0081), and attained a target trough concentration more quickly (mean 41.1 hours vs 58.8 hours, p = 0.0118). There were no significant differences in the frequency of serum creatinine elevation or oliguria at the end of therapy.

CONCLUSIONS

Vancomycin loading doses may improve the ability to safely obtain target trough values in hospitalized children.

Weight-based vancomycin loading strategy may not improve achievement of optimal vancomycin concentration in patients with preserved renal function

We performed a retrospective study to evaluate clinical effectiveness of vancomycin loading strategy and factors associated with achieving optimal C _min. Patients administered vancomycin for ≥72 h from January to June 2018 were enrolled. Patients were divided into two groups: loading (LD) and non-loading (NLD). LD was defined as initial vancomycin dose ≥20 mg/kg and ≥120% of maintenance dose. During study period, 70 and 71 received initial LD (24.2 ± 2.5 mg/kg) and NLD (17.3 ± 3.3 mg/kg) doses of vancomycin, respectively (p < .001). Achievement of optimal C _min was not different before administration of the third dose (24.4% in LD versus 18.2% in NLD, p = .484) and within 72 h (22.9% versus 28.2%, p = .759). Risk factors for failure to achieve optimal C _min before administration of the third dose were higher creatinine clearance and higher level of serum albumin. Therefore, more sufficient loading or patient-specific dose strategies should be used to achieve optimal serum vancomycin C _min.

Clinical Pharmacokinetics of Vancomycin in Critically Ill Children

BACKGROUND AND OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Relationship Status between Vancomycin Loading Dose and Treatment Failure in Patients with MRSA Bacteremia: It's Complicated

INTRODUCTION

A one-time vancomycin loading dose of 25-30 mg/kg is recommended in the current iteration of the vancomycin consensus guidelines in order to more rapidly achieve target serum concentrations and hasten clinical improvement. However, there are few clinical data to support this practice, and the extents of its benefits are largely unknown.

METHODS

A multicenter, retrospective, cohort study was performed to assess the impact of a vancomycin loading dose (≥ 20 mg/kg) on clinical outcomes and rates of nephrotoxicity in patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia. The study matched patients in a 1:1 fashion based on age, Pitt bacteremia score, and bacteremia source. The primary outcome was composite treatment failure (30-day mortality, bacteremia duration ≥ 7 days after vancomycin initiation, persistent signs and symptoms of infection ≥ 7 days after vancomycin initiation, or switch to an alternative antimicrobial agent). Secondary outcomes included duration of bacteremia, length of stay post-bacteremia onset, and nephrotoxicity.

RESULTS

A total of 316 patients with MRSA bacteremia were included. Median first doses in the loading dose and non-loading dose groups were 23.0 mg/kg and 14.3 mg/kg, respectively (P < 0.001). No difference was found in composite failure rates between the non-loading dose and loading dose groups (40.5% vs. 36.7%; P = 0.488) or in the incidence of nephrotoxicity (12.7% vs. 16.5%; P = 0.347). While multivariable regression modeling showed receipt of a vancomycin loading dose on a mg/kg basis was not significantly associated with composite failure [aOR 0.612, 95% CI (0.368-1.019)]; post hoc analyses demonstrated that initial doses ≥ 1750 mg were independently protective against failure [aOR 0.506, 95% CI (0.284-0.902)] without increasing the risk for nephrotoxicity [aOR 0.909, 95% CI (0.432-1.911)].

CONCLUSION

These findings suggest that initial vancomycin doses above a certain threshold may decrease clinical failures without increasing toxicity and that weight-based dosing might not be the optimal strategy.

The clinical efficacy and safety of vancomycin loading dose: A systematic review and meta-analysis

BACKGROUND

The clinical significance of using vancomycin loading dose remains controversial. A systematic review and meta-analysis were performed to assess the clinical efficacy and safety of vancomycin loading dose in the treatment of infections.

METHODS

The Pubmed, Embase, Web of Science, and Cochrane Library databases were searched from their inception up to 5 May 2019. Randomized controlled trials (RCTs) and other observational studies were included if they provided clinical outcomes or trough concentrations of vancomycin loading dose (20-30 mg/kg) and conventional-dose (10-20 mg/kg) in the treatment of infections. Achievement of therapeutic concentration (serum trough concentrations of vancomycin reached 15-20 mg/L before the second dose), clinical response (clinical improvement or culture-negative), nephrotoxicity (serum creatinine increase ≥0.5 mg/dL or ≥50% increasing from the baseline), other adverse events (including pruritus, flushing, rash, and/or red man syndrome), and mortality were analyzed. Heterogeneity was identified using the Cochrane I statistic, and P-value <.10 or I-values >50% indicated significant heterogeneity. Pooled estimates of the intervention effects were determined by the odds ratios (ORs) and 95% confidence intervals (CIs) in Review Manager program, version 5.3.5.

RESULTS

Two RCTs and 7 cohort studies including 2816 infected patients were selected for the analysis, in which serum trough concentrations of vancomycin following the use of vancomycin loading dose or other outcomes were available. Loading dose group had a significantly higher compliance rate of serum trough concentration of 15 to 20 mg/L (OR = 3.06; 95% CI = 1.15-8.15; P = .03) and significantly lower incidence of nephrotoxicity (OR = 0.59, 95% CI = 0.40-0.87; P = .008; I = 29%) compared with control group. No significant difference was noted between loading dose group and control group in terms of other adverse events and clinical response (OR = 1.98, 95% CI = 0.80-4.93; P = .14; I = 0%). The use of vancomycin loading doses in patients can indeed increase the achievement of therapeutic concentration.

CONCLUSION

Vancomycin loading dose increases the achievement of therapeutic concentration without bringing extra risk of nephrotoxicity. However, well-designed large-scale RCTs remain needed to validate the clinical efficacy of vancomycin loading dose and to further evaluate other adverse reactions and mortality.PROSPERO registration number CRD42018093927.

The Effect of Hypoalbuminemia on the Therapeutic Concentration and Dosage of Vancomycin in Critically Ill Septic Patients in Low-Resource Countries

Purpose:

To determine whether severe hypoalbuminemia (<25 mg/L) has a significant effect on serum levels of vancomycin and whether it can effect vancomycin dosage regimen and the loading dose administration.

Material and Methods:

Prospective, cohort, and a single-center study included 61 patients whose vancomycin serum levels were measured in steady state. Vancomycin trough levels (C_min) that were in the range 15 to 20 µg/mL were considered therapeutic and trough levels higher than 15 µg/mL were considered potentially nephrotoxic.

Results:

In the group of patients with severe hypoalbuminemia, C_min was significantly higher compared to the those with nonsevere hypoalbuminemia (>25 mg/L; 23.04 [19.14] vs 13.28 [11.28], P = .01). In the group of patients who received the vancomycin loading dose of 2 g, C_min was significantly higher in patients with severe hypoalbuminemia compared to the patients with nonsevere hypoalbuminemia (34.52 [25.93] vs 15.37 [10.48], P = .04).

Conclusion:

In critically ill septic patients with severe hypoalbuminemia, there is a high probability that the loading dose of vancomycin is not necessary since it is associated with potentially toxic vancomycin C_min, while in the patients with nonsevere hypoalbuminemia the loading dose may be necessary to achieving therapeutic C_min.

Evaluation of vancomycin therapy in the adult ICUs of a teaching hospital in southern Iran

BACKGROUND

Vancomycin resistance in intensive care units (ICUs) accounts for significant morbidity and excess costs. The objective of the present study was to determine the appropriateness of vancomycin use in the various ICUs of Nemazee Hospital, Shiraz, Iran.

METHODS

This prospective study was performed on 95 critically ill patients (48 males and 47 females) who were treated with vancomycin for at least 3 subsequent doses in 6 ICUs during 12 months. Required demographic, clinical, and paraclinical data were collected by a pharmacist. Fifteen indexes were considered for evaluation of vancomycin use.

RESULTS

Ventilator-associated hospital-acquired pneumonia (22.6%), sepsis (22.1%) and CNS infection (12.6%) were found to be the most important indications for vancomycin prescription. Vancomycin was prescribed empirically in 81% of patients. None of the patients received loading dose, and most of the patients received fixed dose. The rate of prolonged empiric antibiotic therapy was 68.5% in patients who received vancomycin. The mean score of vancomycin use in the ICUs of Nemazee Hospital was 7.1±0.6 out of 15, implying that the rate of vancomycin use was in accordance with the guideline proposed by the Department of Clinical Pharmacy of Nemazee Hospital based on Infectious Diseases Society of America by 47.3%.

CONCLUSION

Based on our results, the weakness in using vancomycin was related to not administering loading dose, the practice of prescribing fixed-dose vancomycin and prolonged duration of empiric therapy. Efforts to improve the pattern of vancomycin prescription and utilization in these ICUs should be undertaken.

The effects of major burn related pathophysiological changes on the pharmacokinetics and pharmacodynamics of drug use: An appraisal utilizing antibiotics

Patients suffering major burn injury represent a unique population of critically ill patients. Widespread skin and tissue damage causes release of systemic inflammatory mediators that promote endothelial leak, extravascular fluid shifts, and cardiovascular derangement. This phase is characterized by relative intra-vascular hypovolaemia and poor peripheral perfusion. Large volume intravenous fluid resuscitation is generally required. The patients' clinical course is then typically complicated by ongoing inflammation, protein catabolism, and marked haemodynamic perturbation. At all times, drug distribution, metabolism, and elimination are grossly distorted. For hydrophilic agents, changes in volume of distribution and clearance are marked, resulting in potentially sub-optimal drug exposure. In the case of antibiotics, this may then promote treatment failure, or the development of bacterial drug resistance. As such, empirical dose selection and pharmaceutical development must consider these features, with the application of strategies that attempt to counter the unique pharmacokinetic changes encountered in this setting.

Pharmacokinetic Assessment of Vancomycin Loading Dose in Critically Ill Patients

The vancomycin loading dose (LD) of 25 to 30 mg/kg is a frequently practiced strategy to achieve effective concentrations from the first-treatment dose. However, considering only the body weight for dosing might be inadequate in critically ill patients due to pharmacokinetics changes. We sought to assess achieving optimal trough serum levels of vancomycin and AUC_0-24/MIC in the first 24 h of treatment by using an LD based on population pharmacokinetic parameters of critically ill patients. We performed a concurrent cohort study over 22 months of patients with severe sepsis who received intravenous vancomycin. The patients were treated with three different strategies to initiate vancomycin: without an LD (group A), with an LD of 25 to 30 mg/kg (group B), and with an LD based on population pharmacokinetic parameters of the critically ill patient (group C). An optimal trough serum concentration was achieved in 5, 9, and 83% of patients in groups A, B, and C, respectively. The number of patients that reached optimal AUC_0-24 was 2 of 18 (11%), 5 of 11 (46%), and 11 of 12 (92%) in groups A, B, and C, respectively. The statistical analysis for both parameters revealed significant differences in group C with respect to other groups. The administration of the LD calculated from population pharmacokinetic parameters from the beginning of therapy is a more efficient strategy to obtain adequate trough serum concentrations and AUC_0-24/MIC in critical patients.

A simulation of loading doses for vancomycin continuous infusion regimens in intensive care

BACKGROUND

Delayed achievement of target vancomycin serum concentrations may adversely affect clinical outcomes. The objective of this retrospective study was to compare the prediction accuracy of different body weight descriptors for volume of distribution and to propose an optimal loading dose (LD) for continuous infusion regimens in adults.

METHODS

Pharmacokinetic variables were computed using one-compartmental analysis. Simulated LDs of vancomycin were evaluated for each patient.

RESULTS

Volume of distribution, clearance, and half-life median values (interquartile range) for vancomycin in the study population (n = 30) were 0.45 (0.39-0.61) L.kg^-1, 0.026 (0.015-0.040) L.h^-1.kg^-1, and 10.3 (7.7-21.3) h, respectively. The observed volume of distribution was better predicted by total body weight (TBW) than by the ideal body weight or the adjusted body weight.

CONCLUSIONS

An LD of 10.7 mg per kg TBW was optimal in our study population. Using this LD, 17.9% of simulated vancomycin serum levels were just below the therapeutic range, only 10.7% concentrations exceeded the target range and no concentration was toxic. The use of a LD would lead to reduced median time to reach target concentrations from 17 to 1 h.

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.

Optimizing the Clinical Use of Vancomycin

The increasing number of infections produced by beta-lactam-resistant Gram-positive bacteria and the morbidity secondary to these infections make it necessary to optimize the use of vancomycin. In 2009, the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, and the Society of Infectious Disease Pharmacists published specific guidelines about vancomycin dosage and monitoring. However, these guidelines have not been updated in the past 6 years. This review analyzes the new available information about vancomycin published in recent years regarding pharmacokinetics and pharmacodynamics, serum concentration monitoring, and optimal vancomycin dosing in special situations (obese people, burn patients, renal replacement therapy, among others). Vancomycin efficacy is linked to a correct dosage which should aim to reach an area under the curve (AUC)/MIC ratio of ≥400; serum trough levels of 15 to 20 mg/liter are considered a surrogate marker of an AUC/MIC ratio of ≥400 for a MIC of ≤1 mg/liter. For Staphylococcus aureus strains presenting with a MIC >1 mg/liter, an alternative agent should be considered. Vancomycin doses must be adjusted according to body weight and the plasma trough levels of the drug. Nephrotoxicity has been associated with target vancomycin trough levels above 15 mg/liter. Continuous infusion is an option, especially for patients at high risk of renal impairment or unstable vancomycin clearance. In such cases, vancomycin plasma steady-state level and creatinine monitoring are strongly indicated.

Optimization of time to initial vancomycin target trough improves clinical outcomes

BACKGROUND

Outcomes data for the efficacy of interventions designed to decrease the time to initial target vancomycin troughs are sparse.

OBJECTIVE

A vancomycin therapeutic drug monitoring (TDM) program was initiated to reduce the time to initial target troughs and to examine the impact on clinical outcomes.

METHODS

Single-center, pre- and post-intervention observational study in a 250 bed teaching facility. Adult inpatients treated with physician-guided, vancomycin therapy (historical control, CTRL) were compared to high trough, pharmacist-guided vancomycin therapy (TDM). Nephrotoxicity analyses were conducted to the ensure safety of the TDM. Clinical outcome analysis was limited to patients with normal renal function and culture-confirmed gram positive infections and a pre-defined MRSA subset.

RESULTS

340 patients met initial inclusion criteria for the nephrotoxicity analysis (TDM, n = 173; CTRL, n = 167). Acute kidney injury occurrence was similar between the CTRL (n = 20) and TDM (n = 23) groups (p = 0.7). Further exclusions yielded 145 patients with gram positive infections for clinical outcomes evaluation (TDM, n = 66; CTRL, n = 75). The time to initial target trough was shorter in the TDM group (3 vs. 5 days, p < 0.001). Patients in the TDM group discharged from the hospital more rapidly, 7 vs. 14 days (Hazards Ratio (HR), 1.41; 95% Confidence Interval [CI] 1.08-1.83; p = 0.01), reached clinical stability faster, 4 vs. 8 days (HR, 1.51; 95% CI 1.08-2.11; p = 0.02), and had shorter courses of vancomycin, 4 vs. 7 days (HR, 1.5; 95% CI 1.15-1.95; p = 0.003). In the MRSA infection subset (TDM, n = 36; CTRL, n = 35), patients in the TDM group discharged from the hospital more rapidly, 7 vs. 16 days (HR, 1.89; 95% CI 1.08-3.3; p = 0.03), reached clinical stability faster, 4 vs. 6 days (HR, 2.69; 95% CI 1.27-5.7; p = 0.01), and had shorter courses of vancomycin, 5 vs. 8 days (HR, 2.52; 95% CI 1.38-4.6; p = 0.003). Attaining initial target troughs in <5 days versus ≥5 days was associated with improved clinical outcomes. All cause in-hospital mortality, and vancomycin treatment failure occurred at comparable rates between groups.

CONCLUSIONS

Interventions designed to decrease the time to reach initial target vancomycin troughs can improve clinical outcomes in gram positive infections, and in particular MRSA infections.

Selective vancomycin detection using optical fibre long period gratings functionalised with molecularly imprinted polymer nanoparticles

An optical fibre long period grating (LPG) sensor modified with molecularly imprinted polymer nanoparticles (nanoMIPs) for the specific detection of antibiotics is presented. The operation of the sensor is based on the measurement of changes in refractive index induced by the interaction of nanoMIPs deposited onto the cladding of the LPG with free vancomycin (VA). The binding of nanoMIPs to vancomycin was characterised by a binding constant of 4.3 ± 0.1 × 10(-8) M. The lowest concentration of analyte measured by the fibre sensor was 10 nM. In addition, the sensor exhibited selectivity, as much smaller responses were obtained for high concentrations (∼700 μM) of other commonly prescribed antibiotics such as amoxicillin, bleomycin and gentamicin. In addition, the response of the sensor was characterised in a complex matrix, porcine plasma, spiked with 10 μM of VA.

Multidrug-Resistant Organisms: Considerations in Antibiotic Selection and Administration

Managing infections caused by multidrug-resistant organisms is a significant clinical challenge. Multidrug-resistant organisms' treatment is complicated in the pediatric population because of the lack of primary data, treatment guidelines, rapidly changing pharmacokinetic/pharmacodynamic parameters, and fewer approved antibiotic indications and dosing guidance. Treatment decisions must incorporate available pediatric data, clinical experience, and careful extrapolation from adult data while considering the unique challenges faced by children with complicated infections.

Vancomycin loading doses: a systematic review

OBJECTIVE

To systematically assess the literature to ascertain the pharmacokinetics, pharmacodynamics, and clinical efficacy and safety associated with administration of a vancomycin loading dose (LD).

DATA SOURCES

MEDLINE (1948-December 31, 2014), EMBASE (1980-December 31, 2014), Cochrane Central Register of Controlled Trials, International Pharmaceutical Abstracts (1970-December 31, 2014), Google and Google Scholar, and International Clinical Trials Registry Platform were searched using the following terms: vancomycin, glycopeptides, loading dose, dose-response relationship.

STUDY SELECTION AND DATA EXTRACTION

Pharmacokinetic, pharmacodynamic, and clinical efficacy studies using vancomycin LDs to achieve trough concentrations of 15 to 20 mg/L were included. Nonhuman, non-English, oral vancomycin, and dialysis patient studies were excluded. Abstracts were included. Study quality was ranked using US Preventative Services Task Force 1996 classification system. Data on study design, baseline characteristics, exclusion criteria, dosing, study outcomes, and conclusions were extracted.

DATA SYNTHESIS

A total of 8 studies (5 manuscripts [2 level I, 3 level II-3] and 3 abstracts) were cited. Of 6 adult studies, 4 concluded that administration of vancomycin LDs resulted in significantly more patients achieving troughs of 15 to 20 mg/L. Studies in children found that LDs did not lead to rapid attainment of vancomycin levels ≥15 mg/L. No studies assessed clinical or microbiological outcomes. Limitations included heterogeneity and inconsistent timing of concentration measurements.

CONCLUSIONS

High-quality data to guide the use of vancomycin LDs are lacking. LDs may more rapidly attain vancomycin troughs of 15 to 20 mg/L in adults, but information in pediatrics, obesity, and renal impairment is limited. Further studies are required to determine benefit of LDs on clinical and microbiological outcomes.

Antibiotic Dosing in Patients With Acute Kidney Injury: "Enough But Not Too Much"

Increasing evidence suggests that antibiotic dosing in critically ill patients with acute kidney injury (AKI) often does not achieve pharmacodynamic goals, and the continued high mortality rate due to infectious causes appears to confirm these findings. Although there are compelling reasons why clinicians should use more aggressive antibiotic dosing, particularly in patients receiving aggressive renal replacement therapies, concerns for toxicity associated with higher doses are real. The presence of multisystem organ failure and polypharmacy predispose these patients to drug toxicity. This article examines the pharmacokinetic and pharmacodynamic consequences of critical illness, AKI, and renal replacement therapy and describes potential solutions to help clinicians give "enough but not too much" in these very complicated patients.

Serum cystatin C predicts vancomycin trough levels better than serum creatinine in hospitalized patients: a cohort study

INTRODUCTION

Serum cystatin C can improve glomerular filtration rate (GFR) estimation over creatinine alone, but whether this translates into clinically relevant improvements in drug dosing is unclear.

METHODS

This prospective cohort study enrolled adults receiving scheduled intravenous vancomycin while hospitalized at the Mayo Clinic in 2012. Vancomycin dosing was based on weight, serum creatinine with the Cockcroft-Gault equation, and clinical judgment. Cystatin C was later assayed from the stored serum used for the creatinine-based dosing. Vancomycin trough prediction models were developed by using factors available at therapy initiation. Residuals from each model were used to predict the proportion of patients who would have achieved the target trough with the model compared with that observed with usual care.

RESULTS

Of 173 patients enrolled, only 35 (20%) had a trough vancomycin level within their target range (10 to 15 mg/L or 15 to 20 mg/L). Cystatin C-inclusive models better predicted vancomycin troughs than models based upon serum creatinine alone, although both were an improvement over usual care. The optimal model used estimated GFR by the Chronic Kidney Disease Epidemiology Collaborative (CKD-EPI) creatinine-cystatin C equation (R(2) = 0.580). This model is expected to yield 54% (95% confidence interval 45% to 61%) target trough attainment (P <0.001 compared with the 20% with usual care).

CONCLUSIONS

Vancomycin dosing based on standard care with Cockcroft-Gault creatinine clearance yielded poor trough achievement. The developed dosing model with estimated GFR from CKD-EPIcreatinine-cystatin C could yield a 2.5-fold increase in target trough achievement compared with current clinical practice. Although this study is promising, prospective validation of this or similar cystatin C-inclusive dosing models is warranted.

A randomized controlled trial of a vancomycin loading dose in children

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Adherence to the 2009 consensus guidelines for vancomycin dosing and monitoring practices: a cross-sectional survey of U.S. hospitals

STUDY OBJECTIVES

To describe the implementation of vancomycin dosing and monitoring practices recommended by the consensus guidelines in a diverse sample of hospitals, and to identify needs for quality improvement and research.

DESIGN

Cross-sectional study using an online survey instrument.

SETTING

Making a Difference in Infectious Diseases Pharmacotherapy (MAD-ID) Research Network.

PARTICIPANTS

A total of 163 respondents from MAD-ID who work in antimicrobial stewardship and represent unique hospitals.

MEASUREMENTS AND MAIN RESULTS

The survey population represented a wide range of patient populations (96% adult, 49% pediatric, and 23% long-term care) and settings (52% not-for-profit nonuniversity, 31% university based, and 11% for profit). Automatic consultation of pharmacy services for all vancomycin dosing was reported in 51% of the institutions. Among the dosing and monitoring practices endorsed by the consensus guidelines, participant institutions commonly followed these recommendations: use of trough concentrations without peak concentrations, maintenance of trough concentration higher than 10 mg/L, and target trough concentrations of 15-20 mg/L for complicated infections. In contrast, there was less consistent application of appropriate timing of trough concentrations, use of loading doses, and use of actual body weight. The remaining challenges and controversies surrounding vancomycin dosing are discussed.

CONCLUSION

Despite the availability of consensus guideline recommendations, practices for dosing and monitoring of vancomycin are not universally applied. The findings of this survey highlight many opportunities for future research and quality improvement strategies.