Objective: Improving vancomycin therapy with therapeutic drug monitoring is recommended. Over the past few years, a few studies have demonstrated that trough concentrations may not be the optimal parameter for monitoring vancomycin concentration and Area under the curve (AUC) should be used instead. In this study authors evaluate two methods to estimate the AUC. The first method is based on linear regression using only a trough concentration. The second method uses a simplified two-sample equation-based strategy to estimate the AUC.
Methods: Data from 70 infant patients were collected retrospectively from their medical records at King Saud University Medical City. The prediction accuracy for vancomycin therapy monitoring was optimized by comparing the two methods for the AUC calculation, the simple linear regression and simplified two-sample equation-based strategy.
Results: The target AUC > 400 μg × h/ml was achieved in 10%, 71%, and 100% of patients with trough concentration ranges of 5-10, 10-15, and > 15 μg/ml, respectively. There was a strong correlation between the predicted and observed AUC calculated using the simplified two-sample equation-based strategy (R2 = 0.91, bias = -3.9%, precision =12%).
Conclusions: The target AUC > 400 μg × h/ml can be achieved at trough concentrations <15 μg/ml in most patients. Targeting trough concentrations >15 can lead to overdoing and increase risk of nephrotoxicity. The authors recommend estimating the AUC using the simplified two-sample equation strategy for more precise dosing of vancomycin. Using AUC-guided dosing instead of the trough-guided approach can prevent over dosing and reduce the risk of nephrotoxicity.
Keywords: Dosing; Infants; Pharmacokinetics; Vancomycin.