Intravenous Vancomycin Dosing in the Elderly: A Focus on Clinical Issues and Practical Application

Impacts of age and BMI on vancomycin model choice in a Bayesian software: Lessons from a very large multi-site retrospective study

BACKGROUND

Model-informed precision dosing (MIPD) optimizes drug doses based on pharmacokinetic (PK) model predictions, necessitating careful selection of models tailored to patient characteristics. This study evaluates the predictive performance of various vancomycin PK models across diverse age and BMI categories, drawing insights from a large multi-site database.

METHODS

Adults receiving vancomycin intravenous therapy at United States health systems between January 1, 2022, and December 31, 2023, were included. Patient demographics, vancomycin administration records, and therapeutic drug monitoring levels (TDMs) were collected from the InsightRX database. Age and body mass index (BMI)-based subgroups were formed to assess model performance, with predictions made iteratively. The optimal model for each age-BMI subgroup was chosen based on predefined criteria: models were filtered for mean percentage error (MPE) ≤ 20% and normalized root mean squared error (RMSE) < 8 mg/L, and then the most accurate among them was selected.

RESULTS

A total of 384,876 treatment courses across 155 US health systems were analyzed, contributing 841,604 TDMs. Eleven models were compared, showing varying accuracy across age-BMI categories (41%-73%), with higher accuracy observed once TDMs were available for Bayesian estimates of individual PK parameters. Models performed more poorly in younger adults compared to older adults, and the optimal model differed depending on age-BMI categories and prediction methods. Notably, in the a priori period, the Colin model performed best in adults aged 18-64 years across most BMI categories; the Goti/Tong model performed best in the older, non-obese adults; and the Hughes model performed best in many of the obese categories.

CONCLUSION

Our study identifies specific vancomycin PK models that demonstrate superior predictions across age-BMI categories in MIPD applications. Our findings underscore the importance of tailored model selection for vancomycin management, especially highlighting the need for improved models in younger adult patients. Further research into the clinical implications of model performance is warranted to enhance patient care outcomes.

Decreased Kidney Function Explains Higher Vancomycin Exposure in Older Adults

INTRODUCTION

Older adults face a higher risk of vancomycin-related toxicity given their (patho)-physiological changes, making early management of supratherapeutic exposure crucial. Yet, data on vancomycin exposure in older adults is scarce. This study aims to compare vancomycin concentrations between older and younger patients, emphasizing supratherapeutic concentrations and the effect of patient characteristics.

METHODS

This observational retrospective study was conducted in the University Hospital of Leuven (EC Research S65213). We analyzed early (first) vancomycin concentrations between older (≥ 75 years) and younger patients. Multivariable analyses were conducted to evaluate the association between baseline patient characteristics with supratherapeutic exposure (logistic regression), and dose-normalized concentrations (linear regression).

RESULTS

We included 449 patients aged ≥ 75 years (median 80) and 1609 aged < 75 years (median 61). In univariable analysis, the first-measured vancomycin concentrations were significantly higher in older adults (p < 0.001), who more frequently reached supratherapeutic concentrations (30.7% versus 21%; p < 0.001). In multivariable analysis, factors associated with supratherapeutic concentrations were decreased the estimated glomerular filtration rate calculated by using the Chronic Kidney Disease Epidemiology Collaboration equation (eGFRCKD-EPI) [odds ratio (OR) of 0.98, confidence interval (CI) 0.97-0.98]. Supratherapeutic concentrations had inverse association with giving lower loading dose (OR of 0.59, CI 0.39-0.90), and lower maintenance dose (OR of 0.45, CI 0.26-0.77). Factors that predicted increased dose-normalized concentrations included decreased eGFRCKD-EPI (coefficient of -0.05, CI -0.06 to -0.04), lower body weight (coefficient of -0.04, CI -0.05 to -0.03), increased blood urea nitrogen (coefficient of 0.02, CI 0.01-0.03), and delayed time to therapeutic drug monitoring (TDM) sampling (coefficient of 0.08, CI 0.06-0.09).

CONCLUSIONS

The absence of age as a significant factor in the multivariable analysis suggests that eGFRCKD-EPI mediated the relationship between age and vancomycin exposure. Older adults may benefit more from vancomycin TDM.

The Effect of Topical Vancomycin Powder Application on the Rate of Intervertebral Fusion Following Lumbar Fusion: A Retrospective Study

PURPOSE

The occurrence of surgical site infection (SSI) after lumbar spinal fusion is a serious complication. Therefore, an increasing number of clinicians are applying vancomycin powder topically in the surgical field to reduce the incidence of SSI. However, there is concern that topical vancomycin powder application may affect intervertebral fusion. The purpose of this study was to analyse the effect of clinically relevant topical vancomycin doses on the rate of intervertebral fusion after lumbar fusion and to further investigate the effect of vancomycin powder on the prevention of SSI.

METHODS

The clinical data of 192 patients with degenerative lumbar spine disease admitted from January 2019 to June 2022, all of whom underwent posterior lumbar fusion, were retrospectively analysed. According to the infection prevention protocol, they were divided into a vancomycin group and a control group (no vancomycin), and the vancomycin group was sub-divided into 0.5 g, 1.0 g, and 1.5 g vancomycin groups. General information and surgical evaluation indexes were compared between the control and vancomycin groups and intervertebral fusion was compared between the vancomycin groups at 6 months and 12 months, postoperatively.

RESULTS

The rate of SSI in the vancomycin group was 0.0%, which was significantly lower than that in the control group (5.3%, P < 0.05), and intervertebral fusion was good in all 3 vancomycin groups at 6 months and 12 months postoperatively, with no statistically-significant differences (P > 0.05).

CONCLUSIONS

Topical application of 0.5 g, 1.0 g, or 1.5 g vancomycin powder did not affect the rates of intervertebral fusion after lumbar fusion. In addition, topical application of vancomycin powder significantly reduced the rates of SSI.

Age-Related Differences in Vancomycin-Associated Nephrotoxicity and Efficacy in Methicillin-Resistant Staphylococcus aureus Infection: A Comparative Study between Elderly and Adult Patients

Elderly patients (age ≥ 65 years) are susceptible to methicillin-resistant Staphylococcus aureus (MRSA) infections, with potential for more adverse treatment outcomes or complications compared to younger adults (18-64 years). This study compared vancomycin-associated nephrotoxicity and efficacy in elderly and adult patients and investigated the correlation between vancomycin pharmacokinetic/pharmacodynamic (PK/PD) indices and clinical outcomes. A prospective study was conducted in 10 hospitals in Shanghai from October 2012 to November 2019. A total of 164 patients with MRSA infections were enrolled, including 83 elderly and 81 adult patients. Vancomycin therapeutic drug monitoring (TDM) was performed in all patients, indicating significantly higher vancomycin trough concentrations (Ctrough), 24-h area under the curve (AUC24) values, and AUC24/minimum inhibitory concentration (AUC24/MIC) values in elderly patients compared to adult patients. The incidence of vancomycin-associated nephrotoxicity was nearly three times higher in elderly patients (18.1% vs. 6.2%, p = 0.020), despite similar clinical and microbiological efficacy. Of particular importance, a Ctrough > 20 mg/L was found as an independent factor of nephrotoxicity in elderly patients. Further analysis of patients with an estimated glomerular filtration rate (eGFR) > 60 mL/min/1.73 m2 also revealed that elderly patients had significantly higher vancomycin-related PK/PD indices and more nephrotoxicity than adult patients. In conclusion, elderly patients receiving vancomycin therapy face a higher risk of nephrotoxicity, which requires close vancomycin TDM, especially when the Ctrough exceeds 20 mg/L.

Reconsideration of the current models of estimated kidney function-based drug dose adjustment in older adults: The role of biological age

Human lifespan has increased from a median of 46.5 years in 1950 to 71.7 years in 2022. As people age, one of the inevitable consequences is a decline in kidney function and glomerular filtration rate (GFR) which can have direct or indirect effects on the pharmacokinetic and pharmacodynamic profiles of many drugs. Numerous equations have been developed to generate estimated GFR (eGFR) using the two principal biomarkers: serum creatinine and serum cystatin C. However, the trajectory of changes with aging is dissimilar in these equations. In addition, there is recognition that chronological age (lifespan) often does not reflect biological age (healthspan) as an essential parameter in kidney function equations. In the past decade, there has been an increasing interest in quantifying biological age and new commercially available assays have entered the marketplace. In this narrative review, we illustrate how dominant equations of eGFR model the fractional change in this parameter very differently across chronological age. In addition, we review various biological age indicators (aging clocks) and challenges to their application in clinical practice. Importantly, by comparing vancomycin's mean clearance as a drug with limited metabolism and unchanged elimination between two age milestones in some recent population pharmacokinetic models, we show how efforts to quantify kidney function in older adults optimally remain under-explored, particularly those at the upper end of their lifespan. We also propose considering new models that integrate biological age as a new pathway to improve precision drug dosing in older adults.

Research progress and future prospects of antimicrobial modified polyetheretherketone (PEEK) for the treatment of bone infections

Infection of the bone is a difficult problem in orthopedic diseases. The key and basis of the treatment of bone infection is the effective control of local infection, as well as the elimination of infection focus and dead cavities. The most commonly used approach utilized for the prevention and management of bone infection is the application of antibiotic bone cement. However, the incorporation of antibiotics into the cement matrix has been found to considerably compromise the mechanical characteristics of bone cement. Moreover, some investigations have indicated that the antibiotic release rate of antibiotic bone cement is relatively low. Polyetheretherketone (PEEK) and its composites have been considered to perfectly address the challenges above, according to its favorable biomechanical characteristics and diverse surface functionalizations. This article provides a comprehensive overview of the recent advancements in the antimicrobial modification of PEEK composites in the field of antibacterial therapy of bone infection. Furthermore, the potential application of PEEK-modified materials in clinical treatment was discussed and predicted.

Pharmacokinetics of Antibacterial Agents in the Elderly: The Body of Evidence

Infections are important factors contributing to the morbidity and mortality among elderly patients. High rates of consumption of antimicrobial agents by the elderly may result in increased risk of toxic reactions, deteriorating functions of various organs and systems and leading to the prolongation of hospital stay, admission to the intensive care unit, disability, and lethal outcome. Both safety and efficacy of antibiotics are determined by the values of their plasma concentrations, widely affected by physiologic and pathologic age-related changes specific for the elderly population. Drug absorption, distribution, metabolism, and excretion are altered in different extents depending on functional and morphological changes in the cardiovascular system, gastrointestinal tract, liver, and kidneys. Water and fat content, skeletal muscle mass, nutritional status, use of concomitant drugs are other determinants of pharmacokinetics changes observed in the elderly. The choice of a proper dosing regimen is essential to provide effective and safe antibiotic therapy in terms of attainment of certain pharmacodynamic targets. The objective of this review is to perform a structure of evidence on the age-related changes contributing to the alteration of pharmacokinetic parameters in the elderly.

Area-Under-Curve-Guided Versus Trough-Guided Monitoring of Vancomycin and Its Impact on Nephrotoxicity: A Systematic Review and Meta-Analysis

BACKGROUND

Conventionally, vancomycin trough levels have been used for therapeutic drug monitoring (TDM). Owing to the increasing evidence of trough levels being poor surrogates of area under the curve (AUC) and the advent of advanced pharmacokinetics software, a paradigm shift has been made toward AUC-guided dosing. This study aims to evaluate the impact of AUC-guided versus trough-guided TDM on vancomycin-associated nephrotoxicity.

METHODS

A systematic review was conducted using PubMed, Embase, Web of Science, Cumulative Index to Nursing and Allied Health Literature, Google scholar, and Cochrane library databases; articles published from January 01, 2009, to January 01, 2021, were retrieved and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist. Studies that evaluated trough-guided or AUC-guided vancomycin TDM and vancomycin-associated nephrotoxicity were included. Random-effects models were used to compare the differences in nephrotoxicity.

RESULTS

Of the 1191 retrieved studies, 57 were included. Most studies included adults and older adults (n = 47, 82.45%). The pooled prevalence of nephrotoxicity was lower in AUC-guided TDM [6.2%; 95% confidence interval (CI): 2.9%-9.5%] than in trough-guided TDM (17.0%; 95% CI: 14.7%-19.2%). Compared with the trough-guided approach, the AUC-guided approach had a lower risk of nephrotoxicity (odds ratio: 0.53; 95% CI: 0.32-0.89). The risk of nephrotoxicity was unaffected by the AUC derivation method. AUC thresholds correlated with nephrotoxicity only within the first 96 hours of therapy.

CONCLUSIONS

The AUC-guided approach had a lower risk of nephrotoxicity, supporting the updated American Society of Health-System Pharmacists guidelines. Further studies are needed to evaluate the optimal AUC-derivation methods and clinical utility of repeated measurements of the AUC and trough levels of vancomycin.

Is Vancomycin More Effective than Taurolidine? Comparative Analysis of Their Preventive Effect against Spinal Infection in 1000 Patients with Spinal Fusion

This study aimed to examine the effect of taurolidine irrigation on preventing surgical site infection by comparing the spinal infection rate after spinal fusion surgery using vancomycin powder application and taurolidine irrigation. Of 1081 participants, 369 underwent taurolidine irrigation, 221 underwent vancomycin powder application, and 491 were controls. Of the 20 surgical site infections (1.85%), 14 occurred in the control group (2.85%), 5 in the vancomycin group (2.26%), and 1 (0.27%) in the taurolidine group. Among the various variables, age at the time of surgery, smoking, surgical site, and hemovac removal time were significant in the univariate logistic regression. The final result was derived after variable selection using the stepwise method. In the univariate model, the odds ratios were 0.09 and 0.79 in each of the vancomycin and taurolidine groups compared to that of the control group. In the multivariate model, the odds ratios were 0.09 and 0.83 in each of the vancomycin and taurolidine groups compared to that of the control group. The preventive effect of vancomycin powder application was not statistically significant. However, the vancomycin group showed a less effective tendency than the taurolidine group. Taurolidine irrigation may be a good substitute for the vancomycin powder application.

Clinical validation of the two-point method for predicting vancomycin AUC based on peak and trough plasma concentrations

BACKGROUND

Vancomycin area under the curve/minimum inhibitory concentration (AUC/MIC) has been proposed as a therapeutic drug monitoring (TDM) target to dose vancomycin. It is time-consuming to estimate AUCs using traditional methods. A two-point trough-peak method is more straightforward for calculating the vancomycin AUC. However, the technique and the AUC/MIC target have not been validated in Chinese patients.

AIM

To compare the clinical outcomes of vancomycin therapy in Chinese older adults (aged > 60 years) between the trough-only and the two-point peak-trough AUC TDM approaches.

METHOD

The patients were divided into study and control groups according to TDM approaches. A trough-based TDM was used in the control group (target trough level 15-20 mg/L). Stanford University has provided a method to predict vancomycin AUC using peak-valley concentration alone (two-point method). A two-point trough-peak TDM approach was employed in the study group (target AUC/MIC ≥ 400). The effect of vancomycin was evaluated in terms of clinical findings, laboratory values, and bacteriologic responses. The effects of treatment and kidney functions were compared between the two groups.

RESULTS

A total of 389 patients met the study inclusion criteria, and 189 were excluded based on the exclusion criteria. Of the 200 patients, 80 received the two-point TDM approach (the study group), and 120 were monitored using the trough-based approach (the control group). The average age was 69.8 ± 7.1 years. Staphylococcus aureus (34%) was the most common Gram-positive bacteria. No vancomycin-related nephrotoxicity was observed in either group. The percentages of patients with an excellent response to vancomycin therapy were significantly higher in the study group than in the control group, 90% (72/80) versus 73.3% (88/120), P = 0.0039.

CONCLUSION

The two-point peak-trough method is practical for obtaining vancomycin AUC. The AUC/MIC ≥ 400 target demonstrates treatment effectiveness and safety in older Chinese patients.

Infective Endocarditis in the Elderly: Challenges and Strategies

The specific management of infective endocarditis (IE) in elderly patients is not specifically addressed in recent guidelines despite its increasing incidence and high mortality in this population. The term "elderly" corresponds to different ages in the literature, but it is defined by considerable comorbidity and heterogeneity. Cancer incidence, specifically colorectal cancer, is increased in older patients with IE and impacts its outcome. Diagnosis of IE in elderly patients is challenging due to the atypical presentation of the disease and the lower performance of imaging studies. Enterococcal etiology is more frequent than in younger patients. Antibiotic treatment should prioritize diminishing adverse effects and drug interactions while maintaining the best efficacy, as surgical treatment is less commonly performed in this population due to the high surgical risk. The global assessment of elderly patients with IE, with particular attention to frailty and geriatric profiles, should be performed by multidisciplinary teams to improve disease management in this population.

Stevens-Johnson Syndrome Following Vancomycin and Linezolid: A Real-World Analysis of Post-Marketing Surveillance Data

Background: Stevens-Johnson syndrome (SJS) has been reported as a serious adverse effect in patients treated with vancomycin or linezolid, and there is currently a lack of real-world studies comparing specific differences in adverse effects of SJS.

Methods: According to the FDA’s Adverse Event Reporting System (FAERS), from January 2004 to July 2021, the data of suspected SJS after the use of vancomycin and linezolid were analyzed by imbalance and Bayesian analysis. The onset time, fatality rate and hospitalization rate of vancomycin-associated SJS and linezolid-associated SJS were also investigated.

Results: 276 cases of vancomycin-related SJS reports and 63 cases of linezolid-related SJS reports were identified. These two drugs are more common in middle-aged patients (45–64 years) than other age groups, and less common in underage children (<18). Among them, linezolid-related SJS is more common in middle-aged and elderly patients (45–74 years old) than other groups. Except for unspecified data, in vancomycin-associated SJS cases, there are more men than women (49.28% vs 43.84%), while in linezolid-associated SJS cases, the proportion of men and women is almost equal (44.44%). From the point of view of the areas where adverse reactions were reported, about 1/2 of the reports on Vancomycin-related SJS came from North America, and 1/3 of the reports came from Europe. The median onset time of Linezolid-related SJS was 5 days (interquartile range [IQR] 2–7.75), which was significantly earlier than that of Vancomycin-related SJS (12 days, IQR 4–20) (Mann-Whitney test, p < 0.0001). There were no significant differences in mortality and hospitalization rates after vancomycin and linezolid caused SJS.

Conclusion: The analysis of faers data provides a comprehensive overview of the adverse reactions of SJS caused by the use of vancomycin and linezolid, and can warn clinical workers to timely intervene and continuously monitor the patients at risk of SJS when using such drugs.

Blood Culture Utilization in the Hospital Setting: a Call for Diagnostic Stewardship

There has been significant progress in detection of bloodstream pathogens in recent decades with the development of more sensitive automated blood culture detection systems and the availability of rapid molecular tests for faster organism identification and detection of resistance genes. However, most blood cultures in clinical practice do not grow organisms, suggesting that suboptimal blood culture collection practices (e.g., suboptimal blood volume) or suboptimal selection of patients to culture (i.e., blood cultures ordered for patients with low likelihood of bacteremia) may be occurring. A national blood culture utilization benchmark does not exist, nor do specific guidelines on when blood cultures are appropriate or when blood cultures are of low value and waste resources. Studies evaluating the potential harm associated with excessive blood cultures have focused on blood culture contamination, which has been associated with significant increases in health care costs and negative consequences for patients related to exposure to unnecessary antibiotics and additional testing. Optimizing blood culture performance is important to ensure bloodstream infections (BSIs) are diagnosed while minimizing adverse events from overuse. In this review, we discuss key factors that influence blood culture performance, with a focus on the preanalytical phase, including technical aspects of the blood culture collection process and blood culture indications. We highlight areas for improvement and make recommendations to improve current blood culture practices among hospitalized patients.

Negligible Systemic Uptake of Suprafascial Vancomycin Powder Following Instrumented Posterior Spinal Fusion-Preliminary Results From A Randomized Clinical Trial (VANCO Trial)

BACKGROUND

Intrawound vancomycin powder is an emerging strategy to reduce surgical site infections (SSIs) in spine surgery. However, there are concerns relating to its safety profile and toxicity. Data on systemic uptake of suprafascially administered vancomycin powder following instrumented spinal fusion is lacking.

OBJECTIVE

To study the systemic uptake and safety of suprafascially administered vancomycin powder in the early postoperative phase following open instrumented posterior spinal fusion.

METHODS

This was a substudy of an ongoing randomized clinical trial. Eligible adult patients were randomized 1:1 to either receive suprafascial vancomycin powder before wound closure or not to receive vancomycin powder. Serum vancomycin levels were assessed on postoperative days 1 and 2, serum creatinine levels were measured pre- and post-operatively. Adverse events up to 6 wk following surgery were recorded.

RESULTS

Among 34 randomized patients (mean age 62 yr, range 31-84 yr; 18 [53%] women), 17 received vancomycin powder. No detectable serum vancomycin levels (>4.0 mg/L) were found. Proportion of adverse events per patient in the vancomycin and control group, respectively, were 29.4% (5/17) vs 11.8% (2/17) (OR 3.12; 95% CI, 0.52; 19.38; P = .398). No patient had nephrotoxicity or ototoxicity in either group.

CONCLUSION

Suprafascial vancomycin powder in open instrumented spinal fusion surgery is safe and results in negligible systemic uptake. Final results of the VANCO Trial need to be awaited for conclusive data on the efficacy of vancomycin for SSI prevention and its impact on wound healing.

Topical Vancomycin for Prevention of Surgical Site Infection after Craniotomy, Meta-analysis and Systematic Literature Review

OBJECTIVE AND DESIGN

There is no consensus among neurosurgeons regarding whether the application of topical vancomycin after performing craniotomy has a role in reduction of the risk surgical site infection and consequently reduction of treatment costs. In order to compare the rate of surgical site infections after craniotomies with and without the use of topical vancomycin, a meta-analysis of the available studies in the literature was carried out.

MATERIALS AND METHODS

Multiple electronic health databases were searched to identify all the studies published from July 1988 to July 2021 that examined the role of application of topical vancomycin in reduction of the risk of surgical site infection after craniotomy (cSSIs). Effect sizes were expressed in pooled odds ratio (OR) estimates and due to heterogeneity between studies, random effect of the inverse variance weighted method was used to perform the meta-analysis.

RESULTS

Three observational retrospective cohort studies and one prospective controlled cohort study were identified, comparing the incidence of surgical site infection after 605 craniotomies in which topical vancomycin was used and after 716 craniotomies in which no such intervention was done. Meta-analysis showed that topical vancomycin decreased incidence of cSSIs (odds ratio, 0.13; 95% confidence interval, 0.04 - 0.43).

CONCLUSIONS

The results of this meta-analysis suggest that the use of topical vancomycin after performing craniotomies is safe and effective in decreasing the incidence of cSSIs, however there is a need to perform randomized controlled trials to strongly support this conclusion.

A meta-analysis of the local application of vancomycin powder to prevent surgical site infection after spinal surgeries

Objective

This study aimed to systematically analyze the effectiveness and safety of the local application of vancomycin powder to prevent surgical site infection (SSI) after spinal surgeries and provide guidance for clinical practice.

Methods

Two researchers independently searched PubMed, Web of Science, Elsevier, and China National Knowledge Infrastructure using the MeSH terms “spinal surgery,” “vancomycin,” “local,” “topical,” “prophylactic,” “surgical site infection,” and “SSI” to identify studies published between January 2010 and January 2020 on the local application of vancomycin powder for preventing SSI after spinal surgeries. The outcome assessment indicators were analyzed using RevMan 5.3 software.

Results

Three randomized controlled trials, two prospective studies, and 26 retrospective studies were included in the current research. The results of the meta-analysis revealed significant differences between the vancomycin and control groups (non-vancomycin group) concerning the incidence of SSI (risk ratio = 0.39, 95% confidence interval = 0.28–0.55, Z = 5.46), indicating that local application of vancomycin powder can significantly reduce the incidence of SSI.

Conclusion

Local application of vancomycin powder is an effective and safe method to prevent SSI after spinal surgeries.

Causes of vancomycin dosing error; problem detection and practical solutions; a retrospective, single-center, cross-sectional study

Vancomycindosing error and inappropriate monitoring is a common problem in hospital daily practice. In King Abdulaziz Medical City (KAMC) in Jeddah, a high percentage of abnormal vancomycin trough levels is still detected despite using the recommended dose. Therefore, the current research objective is to study the major causes of vancomycin dosing errors. This retrospective, single-center, cross-sectional study was carried out at KAMC hospital in Jeddah from January 1st until December 31st 2019. All adult patients (≥15 years) who received vancomycin and had an initial abnormal trough level at the measured steady-state were included in this study. 472 patients have met the study inclusion criteria.

The current study evaluated the factors that play a role in causing vancomycin trough level abnormalities such as sampling time, vancomycin dosing, and patient’s pharmacokinetic and pharmacodynamic variations.

In this study, we found that pharmacokinetic and pharmacodynamic variability was attributed to 65% of vancomycin's abnormal trough level. Also, the result showed a significantly increased odds of the low trough in the non-elderly group (OR 6, 95% CI 2.48 – 14.9, P < 0.001) and febrile neutropenic patients (OR 2.21, 95% CI 1.119 – 4.365, P < 0.05). However, the odds of high trough levels were significantly elevated among patients who have CrCl < 50 ml/min (OR 5, 95% CI 1.262–20.539, P < 0.05). In addition, the present investigation revealed that the occurrence of abnormal vancomycin levels was not affected by daily duty time or working days (p > 0.05). The current study indicated that vancomycin dosing errors were common in KAMC patients; thus, there is an unmet need to evaluate the causes of vancomycin abnormal trough level and optimize a strategy that would enhance the therapeutic effectiveness and minimize the potential toxicity.

Attention to age: similar dosing regimens lead to different vancomycin levels among older and younger patients

BACKGROUND

little is known on the clinical implications of vancomycin trough levels among older patients.

OBJECTIVE

to evaluate the association between vancomycin levels and outcomes among older versus younger patients.

DESIGN

retrospective study.

SUBJECTS

patients aged 18-64 and ≥65 years treated with vancomycin for documented methicillin resistant Staphylococcus aureus (MRSA) infections.

METHODS

we compared the effectiveness and toxicity of vancomycin according to trough levels in older versus younger patients. Subgroup analysis of patients with glomerular filtration rate (GFR) > 60 ml/min/1.73 m2 was performed.

RESULTS

we included 181 patients aged ≥65 years and 104 younger patients. Mean age in the older group was 76.9 ± 8 years versus 50.9 ± 12.4 in the younger group. Vancomycin trough levels and 24-hours area under the curve to minimal inhibitory concentrations (AUC/MIC) were significantly higher in older patients who were also significantly more likely to achieve trough levels of ≥15 mg/l within 4 days, (98/181 (54.1%) vs. 38/104 (36.5%) in younger patients, P = 0.004). Results were similar among patients with GFR > 60. Thirty-day mortality was significantly higher in older (74/181, 40.9% vs. 13/104, 12.5%, respectively, P < 0.001). There was no association between vancomycin trough levels and mortality among older patients. No significant differences were demonstrated in clinical or microbiological success or nephrotoxicity.

CONCLUSIONS

applying uniform dosing recommendations across age groups among adults with MRSA infections results in higher vancomycin levels and AUC/MIC in older versus younger patients. Yet, mortality rates remain higher among older adults. Prospective studies are needed to define the optimal approach for using this drug in older patients.

Drug-Induced Kidney Injury in the Elderly

The incidence of acute kidney injury in the elderly has grown over the past decade. One of the primary drivers is drug-induced nephrotoxicity, which is the result of a combination of the unique susceptibilities to kidney injury and the increased use of medications in the elderly population. Specific drug classes are associated with increased rates of kidney injury including agents that block the renin angiotensin system, antimicrobials, and chemotherapeutic agents. Mechanistically, injury may be due to hemodynamic effects, tubular or glomerular toxicity, and interstitial nephritis. Early recognition of nephrotoxicity is critical, as are preventative steps when applicable. Unfortunately, treatment for established drug-induced kidney injury is limited and supportive care is required. Limiting exposure to nephrotoxic drugs is critical in decreasing the incidence of acute kidney injury in the elderly patient.