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

Evaluation of the appropriateness of vancomycin therapeutic drug monitoring in the intensive care unit with a clinical pharmacy approach, a cross-sectional study

OBJECTIVES

Vancomycin, a glycopeptide antibiotic has antibacterial activity against Gram-positive bacteria and is frequently used in the intensive care unit (ICU). Inappropriate therapeutic drug monitoring (TDM) of vancomycin is a common problem encountered in hospital daily practice. The aim of this study was to evaluate the appropriateness of vancomycin trough-guided TDM in patients treated in the ICU using a clinical pharmacy approach.

METHODS

The study was conducted retrospectively in patients over 18 years old who had at least one vancomycin trough level and who had received intravenous (IV) vancomycin for ≥3 days between 1 November 2020 and 1 April 2022. The study included 137 patients. Patient demographics and relevant vancomycin TDM data were collected from medical records. The appropriateness of TDM was evaluated according to the criteria established based on the monitoring recommendations specified in consensus guidelines for therapeutic drug monitoring of vancomycin published by the American Society of Health-System Pharmacists (ASHP) in 2009 and 2020.

RESULTS

Of a total of 238 vancomycin trough levels measured in patients, 32.4% were collected at an inappropriate time. When patients were evaluated in terms of TDM appropriateness according to vancomycin level ranges (<10 µg/mL, 10-20 µg/mL and >20 µg/mL), we found the appropriate TDM was significantly higher in the therapeutic range (10-20 µg/mL) (p <0.001). Of the total 238 vancomycin trough concentrations taken from patients, 77 (32.4%) were measured at an inappropriate time. This caused dose withholding, wrong adjustments and therapy failure. The total TDM appropriateness of vancomycin was significantly higher in the therapeutic range defined as 10-20 µg/mL when evaluated based on 'TDM appropriateness criteria' (p <0.001).

CONCLUSION

Our study shows that appropriate vancomycin TDM increases the likelihood of achieving target trough concentrations. Involvement of clinical pharmacists in TDM management may prevent the development of adverse reactions by ensuring appropriate sampling time and appropriate interpretation of vancomycin levels.

Dose optimization and target attainment of vancomycin in children

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

Therapeutic drug monitoring of glycopeptide antimicrobials: An overview of liquid chromatography-tandem mass spectrometry methods

Therapeutic drug monitoring (TDM) is a critical clinical tool used to optimize the safety and effectiveness of drugs by measuring their concentration in biological fluids. These fluids are primarily plasma or blood. TDM, together with real-time dosage adjustment, contributes highly to the successful management of glycopeptide antimicrobial therapies. Understanding pharmacokinetic/pharmacodynamic (PK/PD) properties is vital for optimizing antimicrobial therapies, as the efficacy of these therapies depends on both the exposure of the patient to the drug (PK) and pharmacodynamic (PD) parameters such as the in vitro estimated minimum drug concentration that inhibits bacterial growth (MIC). Liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) is widely recognized as the gold standard for measuring small molecules, such as antibiotics. This review provides a comprehensive overview of LC-MS/MS methods available for TDM of glycopeptide antibiotics, including vancomycin, teicoplanin, dalbavancin, oritavancin, and telavancin.

A Method for Evaluating Robustness of Limited Sampling Strategies—Exemplified by Serum Iohexol Clearance for Determination of Measured Glomerular Filtration Rate

In combination with Bayesian estimates based on a population pharmacokinetic model, limited sampling strategies (LSS) may reduce the number of samples required for individual pharmacokinetic parameter estimations. Such strategies reduce the burden when assessing the area under the concentration versus time curves (AUC) in therapeutic drug monitoring. However, it is not uncommon for the actual sample time to deviate from the optimal one. In this work, we evaluate the robustness of parameter estimations to such deviations in an LSS. A previously developed 4-point LSS for estimation of serum iohexol clearance (i.e., dose/AUC) was used to exemplify the effect of sample time deviations. Two parallel strategies were used: (a) shifting the exact sampling time by an empirical amount of time for each of the four individual sample points, and (b) introducing a random error across all sample points. The investigated iohexol LSS appeared robust to deviations from optimal sample times, both across individual and multiple sample points. The proportion of individuals with a relative error greater than 15% (P15) was 5.3% in the reference run with optimally timed sampling, which increased to a maximum of 8.3% following the introduction of random error in sample time across all four time points. We propose to apply the present method for the validation of LSS developed for clinical use.