Year: 2014
Type: conference-abstract
Abstract: Background. According to the IDSA guidelines, vancomycin trough concentrations are the most accurate and practical method for therapeutic drug monitoring (TDM). Methods. As part of a prospective, 3-year, sequential cohort study of a novel Bayesian vancomycin therapeutic drug monitoring (TDM) strategy, to establish the baseline TDM practice we enrolled 83 patients at our tertiary-care, academic, county hospital during the first year from 2012-2013. Results. Patients were 9 months to 74 years old. The first vancomycin concentration was therapeutic per IDSA guidelines in only 26 (31%) patients, with sampling in 54 (65%) after the 3rd or 4th dose, and before (20%) or after (15%) these doses in the rest. The median sample time after start of therapy was 35 hours (range 8-93 hours). Only 34 (41%) of samples were true troughs drawn within 1 hour before the next planned dose based on the dose interval, and 31 (39%) of 79 were drawn within 1 hour before the next actual dose (4 patients stopped vancomycin). The median true trough was 14.7 mg/L in therapeutic patients and 6.3 mg/L in those that were not therapeutic (p = 0.0008). The median vancomycin dose was 12.5 mg/kg in patients with therapeutic troughs and 13.0 mg/kg in those without (p = 0.88). In 6 (7%) patients with nephrotoxicity, the median vancomycin concentration was 18.1 mg/L vs 11.3 mg/L in patients without renal injury (p = 0.0001). Conclusion. Measurement of true steady-state vancomycin troughs within one hour of the next dose does not happen for the majority of patients in our hospital setting, biasing interpretation from traditional TDM or nomograms that depend on accurate timing. Therapeutic concentrations cannot be predicted from dosing, and non-therapeutic patients are more likely to be underdosed than overdosed. To prevent underdosing and nephrotoxicity from overdosing, routine use of a TDM approach that can handle sample timing variability, such as a Bayesian algorithm, is strongly justified by our data. Testing of the algorithm is ongoing in years 2 and 3 of our study. Disclosures. M. Neely, Applied Pharmacometrics: Co-founder, Seeking to eventually license a Bayesian dosing software program developed by the Laboratory of Applied Pharmacokinetics, of which I am director
Source: Open Forum Infectious Diseases
Language: English
Subfield: Pharmacology
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $4,053
OpenAlex ID: W2270874586