Vancomycin area under the curves estimated with pharmacokinetic equations using trough-only data

Area of Science:

• Pharmacokinetics and Pharmacodynamics
• Infectious Diseases
• Clinical Pharmacy

Background:

• Revised vancomycin guidelines target an AUC of 400-600 mg*hr/L for serious MRSA infections.
• AUC measurement typically requires peak and trough concentrations, necessitating an extra blood sample.
• Estimating AUC from trough-only data is a more practical approach for AUC-guided vancomycin dosing.

Purpose of the Study:

• To compare AUCs estimated from trough-only vancomycin concentrations with AUCs calculated from peak and trough concentrations.
• To develop and validate a population equation for vancomycin volume of distribution (Vd) for AUC estimation.

Main Methods:

• Collected steady-state peak and trough vancomycin data from VancoPK.com.
• Included patients with specific timing criteria for blood sample collection.
• Derived a population Vd equation and compared AUC estimation accuracy and precision using bias, RMSE, and Lin's concordance correlation.

Main Results:

• A total of 4,343 adult patients were analyzed (2,500 in model group, 1,843 in test group).
• The derived Vd equation (Vd (L) = 0.29(age) + 0.33(total BW in kg) + 11) yielded accurate and precise AUC estimates.
• Mean actual AUC was 504 mg*hr/L, estimated AUC was 503 mg*hr/L, with a correlation of 0.926 and RMSE of 47.7.

Conclusions:

• The developed Vd model provides accurate and precise AUC estimates from trough-only vancomycin data.
• This trough-only method simplifies AUC-guided dosing, requiring less blood work compared to peak-trough monitoring.
• AUC calculations are facilitated by practical, open-access online tools.