1571. Evaluation of a Single Post First Dose Vancomycin Level to Achieve a Goal Vancomycin AUC

BACKGROUND: The 24-hour area under the serum concentration–time curve (AUC24) is the most defensible measure to predict the effectiveness and toxicity of vancomycin. The optimal method and time point to assess and optimize AUC24, however, have yet to be determined. Measuring a trough concentration at steady state has been the traditional method of monitoring vancomycin, but trough is unreliable at estimating AUC24. More accurate methods for estimating AUC24 are paired sample analysis, or a single optimally timed sample combined with population pharmacokinetics. We wished to optimize AUC24 prior to steady state for earlier goal attainment, thereby decreasing risk of treatment failure, resistance, and/or nephrotoxicity. A single optimally timed single post first dose level may be used to estimate drug clearance and thereby AUC. Based on the post first dose concentration and a population pharmacokinetic model, clearance is calculated, and the dosing regimen can be adjusted to achieve a desired AUC24. Our institution has enabled pharmacists to obtain post first dose vancomycin levels and make early dose adjustments. The aim of this project is to monitor the accuracy of this method and the outcomes of patients who have received post first dose vancomycin levels and subsequent dose assessment/adjustment. METHODS: Single-center cohort study via electronic chart review of patients with vancomycin therapeutic dose monitoring based on post first dose vancomycin levels obtained between January 2019 and April 2019. RESULTS: 41 patients were dosed and monitored based on post first dose vancomycin levels. Fourteen patients (34%) required dose adjustments based on the post first dose level. Accuracy of assessment was determined in 15 patients (37%) via a steady-state level used to measure vancomycin clearance and AUC24. At steady-state following dose assessment 14/15 (93%) patients had desired targeted goal AUC24. Only two patients (5%) had greater than a 50% increase in baseline serum creatinine. CONCLUSION: Post first dose-level analysis resulted in dose regimen modifications in one-third of patients. This consistently allowed the attainment of goal AUC24 at steady-state. DISCLOSURES: All authors: No reported disclosures.