2025 Southeastern Residency Conference

Title: Impact of a 2,000mg Vancomycin Loading Dose Maximum in Adult Patients


Authors: Tori Parks, Sarah McDaniel, Ashley Lightfoot, Lauren Wright, Josh Settle


Background: Vancomycin is a tricyclic glycopeptide antibiotic that is used to treat gram positive infections including methicillin-resistant Staphylococcus aureus (MRSA) and ampicillin-resistant Enterococcus. Vancomycin has been associated with an increased risk of developing acute kidney injury (AKI). To try to combat this in our patients, the Baptist Health System utilizes both a vancomycin dosing protocol and InsightRx© software to dose and monitor vancomycin for antibiotic area under the curve (AUC) levels and toxicity. InsightRx© is a Bayesian dosing software that utilizes random vancomycin levels to compare individual patients to patients with similar baseline characteristics who have also been entered into the software. This allows InsightRx© to predict how patients will respond to different vancomycin dosing schedules and predict AUC levels, troughs, and toxicity levels. Previously, the Baptist Health System vancomycin dosing protocol allowed for a maximum of a 3000mg vancomycin loading dose.There was thought to be a trend upward in the amount of AKI cases that were being seen in patients who were receiving higher loading doses of vancomycin. For this reason, the protocol was updated in 2023 and went into effect in January of 2024 to reduce the maximum vancomycin loading dose to 2000mg. The objective of this study was to analyze the rates of AKI in patients who received more than a 2000mg vancomycin loading dose before the updated protocol compared to lower loading doses after the implementation of a 2000mg maximum vancomycin loading dose. 
 
 
Methods: This is a investigational review board exempt, retrospective chart review conducted within the Baptist Health system from September to December. All patients admitted to Baptist Medical Center South and Baptist Medical Center East who received vancomycin were identified through an electronic report. After Investigational Review Board (IRB) exemption, a retrospective chart review from September 2023 to December 2023 before the 2000mg loading dose maximum and from January 2024 to July 2024 after the loading dose maximum were evaluated through a chart review and through InsightRx©. Data collected on qualifying patients included demographics, laboratory data, medication administration record data.   


Results: A total of 50 pre-implementation and 50 post-implementation patients were reviewed. Average baseline serum creatinine was 1.36 mg/dL and 1.21 mg/dL respectively. Pre- 2000mg maximum, the rate of AKI was 18%. After the 2000mg maximum the rate of AKI was 10%. Patient receiving loading doses after the 2000mg mg loading dose maximum took longer to reach target AUC (400-600 ug/mL) than patients who received higher loading doses. The implementation of a reduced vancomycin loading dose maximum to 2000mg from 3000mg showed a slight decrease in the rates of AKI, however, these rates cannot be solely attributed to vancomycin loading doses. Reduction of the maximum vancomycin loading dose extended the time to reach therapeutic AUC levels but did not negatively impact clinical outcomes. More research is needed at a larger scale to determine if larger vancomycin loading doses are associated with higher rates of AKI.


Conclusion: The reduction of the vancomycin loading dose maximum to 2000mg decreased the incidence of AKI development by 8% though duration of vancomycin treatment increased by an average of 1.6 days, subsequently increasing the time to reach therapeutic AUC. This change in duration of therapy did not have a negative impact clinical outcomes. The concurrent administration of other nephrotoxic agents could have contributed to the AKI rate. Further research at a larger scale is needed to further analyze the effect of larger vancomycin loading doses on AKI development. Moving forward, the Baptist Health Vancomycin Dosing policy should be evaluated to considered increasing the maximum loading dose of vancomycin to 2500mg from the current 2000mg loading dose maximum.