Chad Nelson, PharmD
Pharmacist
VA Salt Lake City, United States
Disclosure information not submitted.
Jesse Sutton, PharmD
Pharmacist
VA Salt Lake City, United States
Disclosure information not submitted.
Thomas Kerr, PharmD
Pharmacist
VA Salt Lake City, United States
Disclosure information not submitted.
Title: Feasibility of Two-Level Vancomycin AUC-based Pharmacokinetic Monitoring in Critically Ill Patients.
Introduction: In critically ill patients, numerous rapidly changing factors create challenges for appropriate dosing of antimicrobials. Vancomycin has been shown to be one of the most frequently under-dosed antimicrobials in patients with sepsis. Vancomycin troughs are poor surrogates for optimal drug efficacy and trough-based monitoring has been shown to lead to higher rates of nephrotoxicity compared to area under the curve (AUC) based monitoring. Although more optimal, implementation of AUC-based monitoring can be challenging due to education, cost, and other barriers. This study aimed to evaluate the adequacy of vancomycin dosing practices based on trough monitoring and the feasibility of changing to a low cost two-level pharmacokinetic (PK) AUC-based equation in critically ill patients.
Methods: A retrospective chart review between July 1st, 2019 and July 1st, 2020 was conducted on all patients who were administered vancomycin dosed per pharmacy and admitted to an intensive care unit (ICU). Patients were excluded if they had a BMI > 40, amputations, or external administration of vancomycin. Vancomycin dosing adequate was assessed through initial appropriately timed trough levels relative to corresponding pre-specified goals. Safety of the vancomycin protocol was assessed through rate of acute kidney injury (AKI) during vancomycin therapy. Eligibility for AUC-based monitoring using two level pharmacokinetic (PK) equations defined as stable renal function and administration of 4 or more doses was evaluated.
Results: Of the 50 patients included in this study, 12% (n=6) of patients obtained a trough of < 10 mg/L, 42% (n=21) 10-15 mg/L, 36% (n=18) 15-20 mg/L, 10% (n=5) > 20 mg/L. Pre-selected goal troughs were achieved in 46% (n=39) of patients. AKI developed in 8 (16%) of patients. Only 32.8% (n=22) were eligible for AUC-based dosing.
Conclusion: Our current dosing practices appear to be adequate in achieving vancomycin trough goals, although a high rate of AKI was observed. Less than half of the ICU patients were eligible for AUC-based vancomycin dosing using a two-level PK equation. Implementing a two-level PK equation would be low yield and a less feasible approach to vancomycin AUC-monitoring in critically ill patients, therefore Bayesian software may capture a larger subset of our patient population.