Evaluation of a vancomycin dosing nomogram in achieving high target trough concentrations in Taiwanese patients

Prediction of vancomycin initial dosage using artificial intelligence models applying ensemble strategy

BACKGROUND

Antibiotic resistance has become a global concern. Vancomycin is known as the last line of antibiotics, but its treatment index is narrow. Therefore, clinical dosing decisions must be made with the utmost care; such decisions are said to be "suitable" only when both "efficacy" and "safety" are considered. This study presents a model, namely the "ensemble strategy model," to predict the suitability of vancomycin regimens. The experimental data consisted of 2141 "suitable" and "unsuitable" patients tagged with a vancomycin regimen, including six diagnostic input attributes (sex, age, weight, serum creatinine, dosing interval, and total daily dose), and the dataset was normalized into a training dataset, a validation dataset, and a test dataset. AdaBoost.M1, Bagging, fastAdaboost, Neyman-Pearson, and Stacking were used for model training. The "ensemble strategy concept" was then used to arrive at the final decision by voting to build a model for predicting the suitability of vancomycin treatment regimens.

RESULTS

The results of the tenfold cross-validation showed that the average accuracy of the proposed "ensemble strategy model" was 86.51% with a standard deviation of 0.006, and it was robust. In addition, the experimental results of the test dataset revealed that the accuracy, sensitivity, and specificity of the proposed method were 87.54%, 89.25%, and 85.19%, respectively. The accuracy of the five algorithms ranged from 81 to 86%, the sensitivity from 81 to 92%, and the specificity from 77 to 88%. Thus, the experimental results suggest that the model proposed in this study has high accuracy, high sensitivity, and high specificity.

CONCLUSIONS

The "ensemble strategy model" can be used as a reference for the determination of vancomycin doses in clinical treatment.

Impact of pharmacist intervention in reducing vancomycin-associated acute kidney injury: A systematic review and meta-analysis

AIMS

The aim was to quantify the relationship between pharmacist intervention and vancomycin-associated acute kidney injury (AKI).

METHODS

Electronic databases were searched up to August 2020 for meta-analyses of cohort studies and/or randomized controlled trials. Studies that compared the incidence of AKI in patients between post- and prepharmacist intervention were investigated. The primary outcome was incidence of AKI. We also evaluated the influence of pharmacist intervention in risk factors of vancomycin-associated AKI.

RESULTS

The search strategy retrieved 1744 studies and 34 studies with 19 298 participants were included (22 published articles and 12 abstracts from conference proceedings). Compared with the preintervention group, the postintervention group patients had a significantly lower incidence of vancomycin-associated AKI: 7.3% for post- and 9.6% for preintervention (odds ratio [OR] 0.52, 95% confidence interval [CI]; 0.41, 0.67], P < .00001). The rate of attaining target concentration was significantly higher in the post- than preintervention group (OR 2.86, 95% CI [2.23, 3.67], P < .00001). The postintervention group significantly improved the percentage of serum creatinine laboratory tests than preintervention group (OR = 3.24, 95% CI 2.02, 5.19], P < .00001). Patients postintervention had markedly lower risk of mortality than preintervention patients (OR 0.47, 95% CI [0.31, 0.72], P = .0004).

CONCLUSION

Pharmacist intervention in vancomycin treatment significantly decreased the rate of vancomycin-associated AKI, while improving efficacy and reducing mortality. We speculate that this is because the pharmacist interventions optimized the rationality of vancomycin therapy, monitoring of vancomycin trough concentration and the monitoring of patients' renal function.

Dose optimization of vancomycin in obese patients: A systematic review

Background: Dose optimization of vancomycin plays a substantial role in drug pharmacokinetics because of the increased incidence of obesity worldwide. This systematic review was aimed to highlight the current dosing strategy of vancomycin among obese patients. Methods: This systematic review was in concordance with Preferred Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. The literature search was carried out on various databases such as Scopus, PubMed/MEDLINE, ScienceDirect and EMBASE using Keywords and MeSH terms related to vancomycin dosing among obese patients. Google Scholar was also searched for additional articles. The English language articles published after January, 2000 were included in this study. The quality of the study was assessed using different assessment tools for cohort, and case reports. Results: A total of 1,029 records were identified. After screening, 18 studies were included for the final review. Of total, twelve studies are retrospective and remaining six are case-control studies. A total of eight studies were conducted in pediatrics while remaining studies were conducted in adult population. Most of the studies reported the dosing interval every 6-8 h. Differences in target trough concentration exist with respect to target ranges. The administration of loading dose (20-25 mg/kg) followed by maintenance dose (15-25 mg/kg) of vancomycin is recommended in adult patients to target therapeutic outcomes. Moreover, a dose of 40-60 mg/kg/day appears appropriate for pediatric patients. Conclusion: The initial dosing of vancomycin based on TBW could be better predictor of vancomycin trough concentration. However, the clinical significance is uncertain. Therefore, more studies are needed to evaluate the dosing strategy of vancomycin in overweight or obese patients.

Development of a decision flowchart to identify the patients need high-dose vancomycin in early phase of treatment

Background

The standard dose of vancomycin (VCM, 2 g/day) sometimes fails to achieve therapeutic concentration in patients with normal renal function. In this study, we aimed to identify factors to predict patients who require high-dose vancomycin (> 2 g/day) to achieve a therapeutic concentration and to develop a decision flowchart to select these patients prior to VCM administration.

Methods

Patients who had an estimated creatinine clearance using the Cockcroft–Gault equation (eCCr) of ≥50 mL/min and received intravenous VCM were divided into 2 cohorts: an estimation set (n = 146, from April to September 2016) and a validation set (n = 126, from October 2016 to March 2017). In each set, patients requiring ≤2 g/day of VCM to maintain the therapeutic trough concentration (10–20 μg/mL) were defined as standard-dose patients, while those who needed > 2 g/day were defined as high-dose patients. Univariate and multivariate logistic regression analysis was performed to identify the predictive factors for high-dose patients and decision tree analysis was performed to develop decision flowchart to identify high-dose patients.

Results

Among the covariates analyzed, age and eCCr were identified as independent predictors for high-dose patients. Further, the decision tree analysis revealed that eCCr (cut off value = 81.3 mL/min) is the top predictive factor and is followed by age (cut off value = 58 years). Based on these findings, a decision flowchart was constructed, in which patients with eCCr ≥81.3 mL/min and age < 58 years were designated as high-dose patients and other patients were designated as standard-dose patients. Subsequently, we applied this decision flowchart to the validation set and obtained good predictive performance (positive and negative predictive values are 77.6 and 84.4%, respectively).

Conclusion

These results suggest that the decision flowchart constructed in this study provides an important contribution for avoiding underdosing of VCM in patients with eCCr of ≥50 mL/min.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40780-021-00231-w.

Genetic Algorithms as a Tool for Dosing Guideline Optimization: Application to Intermittent Infusion Dosing for Vancomycin in Adults

This paper demonstrates the use of a genetic algorithm (GA) for the optimization of a dosing guideline. GAs are well‐suited to derive combinations of doses and dosing intervals that go into a dosing guideline when the number of possible combinations rule out the calculation of all possible outcomes. GAs also allow for different constraints to be imposed on the optimization process to safeguard the clinical feasibility of the dosing guideline. In this work, we demonstrate the use of a GA for the optimization of intermittent vancomycin administration in adult patients. Constraints were placed on the dose strengths, the length of the dosing intervals, and the maximum infusion rate. In addition, flexibility with respect to the timing of the first maintenance dose was included in the optimization process. The GA‐based optimal solution is compared with the Scottish Antimicrobial Prescribing Group vancomycin guideline.

Relationship of vancomycin trough levels with acute kidney injury risk: an exposure–toxicity meta-analysis

Objectives

Nephrotoxicity represents a major complication of vancomycin administration, leading to high rates of morbidity and treatment failure. The aim of this meta-analysis was to evaluate the association between trough levels and risk of renal impairment, by defining an exposure–toxicity relationship and assessing its accuracy in predicting the development of acute kidney injury (AKI).

Methods

Medline, Scopus, CENTRAL, Clinicaltrials.gov and Google Scholar databases were systematically searched from inception. Studies examining the effects of trough levels on nephrotoxicity risk in adult patients were deemed eligible.

Results

The meta-analysis was based on 60 studies, including 13 304 patients. The development of AKI was significantly linked to both higher initial [standardized mean difference (SMD): 0.82; 95% CI: 0.65–0.98] and maximum (SMD: 1.06; 95% CI: 0.82–1.29) trough levels. Dose–response analysis indicated a curvilinear relationship between trough levels and nephrotoxicity risk (χ2 = 127.1; P value &lt; 0.0001). A cut-off of 15 mg/L detected AKI with a sensitivity of 62.6% (95% CI: 55.6–69.2) and a specificity of 65.5% (95% CI: 58.9–71.6), while applying a 20 mg/L threshold resulted in a sensitivity of 42.9% (95% CI: 34–52.2) and a specificity of 82.5% (95% CI: 73.9–88.8).

Conclusions

The present findings suggest that the development of vancomycin-induced AKI is significantly associated with higher initial and maximum trough levels. An exposure–response relationship was defined, indicating that increasing trough levels correlate with a significant rise of nephrotoxicity risk. Future studies should verify the effectiveness of individualized pharmacokinetic tools that would enable the attainment of trough level targets and minimize the risk of renal toxicity.

Vancomycin loading dose is associated with increased early clinical response without attainment of initial target trough concentration at a steady state in patients with methicillin-resistant Staphylococcus aureus infections

WHAT IS KNOWN AND OBJECTIVE

Vancomycin therapeutic guidelines suggest a loading dose of 25-30 mg/kg for seriously ill patients. However, high-quality data to guide the use of loading doses are lacking. We aimed to evaluate whether a loading dose (a) achieved a target trough concentration at steady state and (b) improved early clinical response.

METHODS

Patients with an estimated glomerular filtration rate ≥ 90 mL/min/1.73 m² were included. A loading dose of 25 mg/kg vancomycin followed by 15 mg/kg twice daily was compared with traditional dosing. A C_min sample was obtained before the fifth dose. An early clinical response 48-72 hours after the start of therapy and clinical success at end of therapy (EOT) was evaluated in patients with methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant coagulase-negative Staphylococci or Enterococcus faecium.

RESULTS

There was no significant difference in C_min between the regimen with and without a loading dose (median: 10.4 and 10.2 µg/mL, P = .54). Proportions of patients achieving 10-20 and 15-20 µg/mL were 56.9% and 5.6%, respectively, in patients with a loading dose. Although there was no significant difference in success rate at EOT between groups, a loading dose was associated with increased early clinical response for all infections (adjusted odds ratio [OR]: 4.588, 95% confidence interval [CI]: 1.373-15.330) and MRSA infections (OR: 12.065, 95% CI: 1.821-79.959). Study limitations included no C_min measurements within 24 hours and the inclusion of less critically ill patients.

WHAT IS NEW AND CONCLUSION

A loading dose of 25 mg/kg followed by 15 mg/kg twice daily did not achieve the optimal Cmin at steady state in patients with normal renal function. However, more early clinical responses were obtained with a loading dose compared with traditional dosing, possibly because of a prompt albeit temporary achievement of a more effective concentration.

The Benefit of Individualized Vancomycin Dosing Via Pharmacokinetic Tools: A Systematic Review and Meta-analysis

Background: Various pharmacokinetic (PK) equations and software have been developed to individualize vancomycin dosing. However, the benefit of using any PK information to guide vancomycin dosing has not been fully elucidated. Objective: To appraise available evidence on the effectiveness and safety of individualized vancomycin dosing via PK tools. Methods: PubMed, EMBASE, the Cochrane Library, and 2 Chinese literature databases were searched through August 1, 2019. Randomized controlled trials (RCTs) and cohort studies that reported the PK and clinical outcomes of individualized vancomycin dosing versus empirical dosing were included. Pooled risk ratios (RRs) and mean differences were calculated for dichotomous and continuous outcomes, respectively. Results: A total of 21 studies involving 4346 patients were finally included, of which 3 were RCTs and 18 were cohort studies. Meta-analysis revealed that PK-guided vancomycin dosing significantly increased the attainment of target trough concentration (RR = 1.59; 95% CI = 1.49-1.70) and decreased the incidence of nephrotoxicity (RR = 0.57; 95% CI = 0.46-0.71). Additionally, the available evidence showed that target area under the curve/minimum inhibitory concentration attainment rate and time to target concentration could improve. However, the evidence on clinical outcomes was scarce, and no significant differences were detected in clinical response rate, microbiological eradication rate, mortality, and length of hospital stay between PK-guided vancomycin dosing and empirical dosing strategies. Conclusion and Relevance: Individualized vancomycin dosing via PK tools significantly increases the attainment of target trough concentration and decreases the incidence of nephrotoxicity. Evidence on clinical effectiveness was limited and showed no significant benefit. Further well-designed studies are warranted to assess its clinical effectiveness and inform routine care.

Development of a Population Pharmacokinetic Model of Vancomycin and its Application in Chinese Geriatric Patients with Pulmonary Infections

Background

The optimal use of vancomycin in the elderly requires information about the drug’s pharmacokinetics and the influence of various factors on the drug’s disposition. However, because of sampling restrictions, it is often difficult to perform traditional pharmacokinetic studies in elderly patients.

Objective

This study was conducted to estimate the population pharmacokinetics of vancomycin in Chinese geriatric patients (age ≥ 65 years) with pulmonary infections and to explore the clinical application of this information for vancomycin dose individualization.

Methods

The steady-state trough concentrations were retrospectively collected from January 2011 to December 2016 and were analyzed using the nonlinear mixed-effect model software. The final model was evaluated using the bootstrap method, goodness-of-fit plots and the normalized prediction distribution error method.

Main Outcome Measure

Model parameters and prediction error.

Results

A total of 125 steady-state trough concentrations from 70 patients were retrospectively collected. A one-compartment model was established. The final model was depicted as clearance (CL) [L/h] = 2.45 × (CL_CR/56.28) × 0.542; volume of distribution (V_d) [L] = 154. The creatinine clearance (CL_CR) was identified as the most significant covariate in the final model. The typical values of CL and V_d in the final model were 2.45 L/h and 154 L, respectively. Model validation outcomes showed that the final model was stable and had satisfactory prediction performance.

Conclusion

A population pharmacokinetic model was established to estimate the pharmacokinetics characteristics of Chinese geriatric patients with pulmonary infections, and this model can be used to develop an initial vancomycin dosing regimen for geriatric patients.

Evaluation of a vancomycin dosing nomogram in obese patients weighing at least 100 kilograms

Background

There remains variability in both practice and evidence related to optimal initial empiric dosing strategies for vancomycin.

Objective

Our primary objective was to describe the percentage of obese patients receiving vancomycin doses consistent with nomogram recommendations achieving targeted initial steady-state serum vancomycin concentrations. Secondary objectives were to describe the primary endpoint in subgroups based on patient weight and estimated creatinine clearance, to describe the rate of supratherapeutic vancomycin accumulation following an initial therapeutic trough concentration, and to describe the rate of vancomycin-related adverse events.

Methods

This single-center, IRB-approved, retrospective cohort included adult patients ≥ 100 kilograms total body weight with a body mass index (BMI) >30 kilograms/m2 who received a stable nomogram-based vancomycin regimen and had at least one steady-state vancomycin trough concentration. Data collected included vancomycin regimens and concentrations, vancomycin indication, serum creatinine, and vancomycin-related adverse events. Patients were divided into two cohorts by goal trough concentration: 10-15 mcg/mL and 15-20 mcg/mL.

Results

Of 325 patients screened, 85 were included. Goal steady-state concentrations were reached in 42/85 (49.4%) of total patients.

Conclusions

Achievement of initial steady-state vancomycin serum concentrations in the present study (approximately 50%) was consistent with the use of published vancomycin dosing nomograms.

Validation of a Nomogram for Achieving Target Trough Concentration of Vancomycin: Accuracy in Patients With Augmented Renal Function

BACKGROUND

Adjustment of initial vancomycin (VCM) dosage has been recommended on the basis of the renal function nomogram in therapeutic drug monitoring guidelines in Japan. However, this nomogram has not been clinically validated, and few studies have focused on its usefulness in patients with risk of augmented renal function. Therefore, this study aimed to evaluate the validity of the VCM nomogram and the association between patient conditions related to augmented renal function and its accuracy.

METHODS

In this retrospective study, we screened data of 398 patients who received VCM and had estimated glomerular filtration rates ≥30 mL·min·1.73 m. Patients who met nomogram dosing criteria were categorized into a nomogram group, and the associations of age, renal function, and individual conditions such as febrile neutropenia, solid tumor, blood cancer, and brain injury with subtherapeutic concentrations (<10.0 mcg/mL) of VCM were evaluated.

RESULTS

In total, 177 patients were categorized into the nomogram group, and 83 (47%), 81 (46%), and 13 patients (7%) had VCM trough concentrations of 10-20, <10, and >20 mcg/mL, respectively. Age <50 years was only significantly associated with subtherapeutic trough concentrations. Specific conditions of patients such as febrile neutropenia, solid tumor, and blood cancer were associated with elevated VCM clearance; however, there was no decline in trough VCM concentrations regardless of the presence of the specific conditions.

CONCLUSIONS

The Japanese VCM dosing nomogram was effective in minimizing the number of instances of supratherapeutic VCM serum concentrations; however, it lacked accuracy in achieving target trough concentrations. The accuracy of the nomogram could be enhanced by categorizing patients according to age. Nevertheless, this study provides novel evidence of the usefulness of this nomogram in avoiding subtherapeutic concentrations of VCM in patients with risk factors for augmented renal clearance.

A Rapid and Simple HPLC Method for Therapeutic Monitoring of Vancomycin

Therapeutic monitoring of the antibiotic vancomycin is important to achieve specific plasma concentration and prevent toxic effects. Several assays have been described for vancomycin determination in clinical practice, but high-performance liquid chromatography is still considered the gold standard for the quantification of vancomycin. In this study, we developed a new and rapid high-performance liquid chromatography method requiring 50 μL of plasma for the quantification of vancomycin. Acetonitrile was used for processing plasma by protein precipitation (1:2.5). Isocratic chromatographic analysis was carried out on a C18 silica-based (2.7 μm) column with the mobile phase containing 20 mM ammonium acetate/formic acid buffer (pH 4.0):methanol 88:12 (v/v). A diode array detector was used for UV detection at 240 nm. This method was validated according to the Brazilian Health Surveillance Agency legislation and International Conference on Harmonization guidelines. The measurement range was 1-100 μg/mL, analysis time was 8 min, and intermediate precision was <12%, supporting the present method as a fast, simple, and effective alternative for therapeutic monitoring of vancomycin.

Assessment of Appropriateness of an Initial Dosing Regimen of Vancomycin and Development of a New Dosing Nomogram

Vancomycin is a glycopeptide antibiotic used to treat Gram-positive infections including methicillin-resistant Staphylococcus aureus (MRSA). The objectives of this study were to evaluate the appropriateness of the initial dosing regimen of vancomycin, identify factors to be considered in regimen selection and develop a new dosing nomogram. Therapeutic drug monitoring (TDM) data of vancomycin obtained from Seoul National University Hospital from 2011 to 2013 were included in this analysis. The vancomycin trough concentrations at steady-state were estimated using Abbott's PKS software program and then categorized into three levels: subtherapeutic, therapeutic and toxic. The newly developed nomograms were evaluated by analysing the percentage of patients with target vancomycin trough concentration using the data of 2,570 patients of the first TDM cases. Therapeutic level was achieved only in approximately one-fifth of the cases, while 56.0% and 23.8% of the TDMs were considered subtherapeutic and toxic, respectively. As body-weight and creatinine clearance (CrCL) increased, the proportion of patients with a subtherapeutic level increased. Using the newly developed nomogram increased the proportion of patients who achieved therapeutic levels from 23.1% to 45.0% or 13.8% to 36.2% (target, 10-15 and 15-20 mg/L, respectively). These results suggest that the vancomycin concentrations fail to reach the therapeutic level or exceed the safe upper margin of the therapeutic level depending on age, body-weight and CrCL. Considering these factors, the new nomograms provide a strategy to achieve target concentrations of vancomycin more rapidly than existing regimens.

The safety and efficacy of high versus low vancomycin trough levels in the treatment of patients with infections caused by methicillin-resistant Staphylococcus aureus: a meta-analysis

BACKGROUND

Recent guidelines have recommended vancomycin trough levels of 15-20 mg/L for treatment of serious infections caused by methicillin-resistant Staphylococcus aureus (MRSA). However, high trough levels may increase risk of nephrotoxicity and mortality, and high vancomycin trough levels have not been well studied. This study was designed to combine safety and efficacy results from independent studies and to compare between high and low vancomycin trough levels in the treatment of MRSA-infected patients using meta-analysis.

METHODS

From 19 eligible studies, 9 studies were included in meta-analysis to compare clinical success between high and low vancomycin trough levels, while 10 and 11 studies met criteria for comparing trough levels and nephrotoxicity and trough levels and mortality, respectively. The PubMed/Medline, Web of Science, and Scopus databases, and hand searching were used to identify eligible studies dated up to March 2016. Of 2344 subjects with MRSA infection, 1036 were assigned to trough levels ≥15 mg/L and 1308 to trough levels <15 mg/L.

RESULTS

High vancomycin trough levels were found to be associated with risk of nephrotoxicity (odds ratio [OR] 2.14, 95 % confidence interval [CI] 1.42-3.23 and adjusted OR 3.33, 95 % CI 1.91-5.79). There was no evidence of difference between high and low vancomycin trough levels for mortality (OR; 1.09; 95 % CI 0.75-1.60) or clinical success (OR 1.07; 95 % CI 0.68-1.68).

CONCLUSION

In this study, high vancomycin trough levels were identified as an independent factor associated with risk of nephrotoxicity in MRSA-infected patients. Association between vancomycin trough levels and both adverse effects and clinical outcomes requires further study.

Vancomycin dosing nomograms targeting high serum trough levels in different populations: pros and cons

PURPOSE

Utilization of higher doses of vancomycin to achieve the trough concentrations of 15-20 mg/L for complicated infections has been recommended by the Infectious Diseases Society of America clinical practice guideline in recent years. Concerning this recommendation, several nomograms have been constructed targeting this optimal trough level range in different populations of patients. In this review, we have collected available nomograms targeting high trough serum levels of vancomycin, particularly comparing their advantages and limitations.

METHOD

The data were collected by searching Scopus, PubMed, Google scholar, Medline, and Cochrane database systematic reviews. The key words used as search terms were "vancomycin", "high trough level", "dosing nomogram", "dosing strategy", "neonates", "critically ill", "pediatrics", and "hemodialysis". We have included 17 related human studies published up to the date of this publication.

RESULTS & CONCLUSION

Most of the available nomograms have determined the doses according to body weight and renal function. Their initial predicting success rate were 44-76 % for non-critically ill patients, 42-84 % for critically ill patients, 54 % for one nomogram specially designed for hemodialysis patients, and 71 % for the only nomogram developed for neonates. Based on validation studies, in most of cases, using a vancomycin dosing nomogram significantly improved and accelerated achievement of target trough concentrations. However, it should be noted that there are limited data about patients' clinical and microbiological outcomes and they are only validated in narrow groups of patients. Thus, their widespread application could not be encouraged for all patients before performing adequately powered, prospective randomized studies.

Evaluation of the Safety of a Vancomycin Nomogram Used to Achieve Target Trough Concentrations

BACKGROUND

Dosing vancomycin to achieve target concentrations of 15 to 20 mg/L has been recommended for select infections. To date, few vancomycin nomograms designed to target these higher concentrations have been published, and only one has been published in North America. Based on the success of this nomogram in developing empiric vancomycin regimens that achieve higher target trough concentrations with low rates of nephrotoxicity, a vancomycin nomogram targeting concentrations of 15 to 20 mg/L was developed and implemented at Emory University Hospital and Emory University Hospital Midtown.

OBJECTIVE

To evaluate the impact of a vancomycin-dosing nomogram on the incidence of vancomycin- associated nephrotoxicity and the time to achieve targeted trough concentrations.

METHODS

A retrospective chart review of 200 patients who received vancomycin dosed to achieve target trough serum concentrations of 15 to 20 mg/L was performed.

RESULTS

After implementation of the vancomycin nomogram, no statistically significant difference in incidence of vancomycin-associated nephrotoxicity was found (14% vs 16%; P = .197). Fewer patients had an initial vancomycin trough concentration within target range (29.1% vs 21.7%; P < .001). Adherence to the nomogram was poor, with only 41% of patients being dosed per the nomogram's recommendations.

CONCLUSION

Based on our results, implementation of a vancomycin dosing nomogram had no impact on the incidence of nephrotoxicity, and significantly fewer patients had an initial vancomycin trough within the target range of 15 to 20 mg/L. The clinical utility of a vancomycin dosing nomogram is still to be determined.

Population pharmacokinetics of vancomycin in adult Chinese patients with post-craniotomy meningitis and its application in individualised dosage regimens

PURPOSE

Vancomycin (VCM) is a first-line antibacterial drug used to treat post-craniotomy meningitis (PCM). VCM pharmacokinetic parameters are altered in PCM patients, compared to those in other patients. Although VCM population pharmacokinetics (PPK) has been reported, changes in VCM PPK in adult Chinese PCM patients remain unknown. We developed a VCM PPK model in adult Chinese PCM patients and proposed a new strategy for individualising VCM administration using this model.

METHODS

Data was obtained from a prospective study of 100 adult PCM patients in the Neurosurgery Department of the First Affiliated Hospital of Fujian Medical University. The trough concentrations at steady state were determined by enzyme multiplied immunoassay. Nonlinear mixed-effect model software was employed to develop the PPK model. The final model was evaluated using the bootstrap method and normalised prediction error distribution and through the testing of 20 independent adult PCM patients.

RESULTS

VCM clearance in PCM patients was higher than that observed in other patients. Creatinine clearance affected VCM clearance, whereas no co-administered drugs influenced VCM pharmacokinetics. Trough concentrations were accurately predicted by the final model, while the prediction errors were less than ±32 %. Moreover, a new strategy for individualising VCM regimens using the PPK model was proposed and validated.

CONCLUSIONS

A PPK model was developed to estimate the individual clearance in inpatients receiving intravenously infused VCM and could be used to develop individualised dosing of adult Chinese PCM patients.

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.

Risk factors for nephrotoxicity in patients receiving outpatient continuous infusions of vancomycin in an Australian tertiary hospital

OBJECTIVES

To assess the risk factors for nephrotoxicity caused by vancomycin continuous infusion in a predominantly Caucasian outpatient population.

METHODS

This was a retrospective cohort study of 155 patient episodes from December 2006 to December 2011.

RESULTS

Vancomycin-associated nephrotoxicity (VN) occurred in 26 of 155 (17%) patient episodes. After adjustment for baseline renal function, maximum steady-state vancomycin concentrations ≥32 mg/L [OR 8.7 (95% CI 3.1-29.6), P < 0.001] and angiotensin receptor blockade [OR 9.78 (95% CI 3.1-39.4), P < 0.001] were independently associated with VN. The cumulative dose and duration of vancomycin therapy were not independent predictors of VN.

CONCLUSIONS

Cessation of angiotensin receptor-blocking medications in selected patient groups, enhanced monitoring and establishing target steady-state concentrations <30 mg/L to avoid excessive vancomycin exposure may reduce the risk of VN.