Weight-based versus set dosing of vancomycin for coronary artery bypass grafting or aortic valve surgery

Objectives This study was undertaken to identify a preferred dosing strategy for patients undergoing coronary artery bypass grafting or valve replacement procedures with cardiopulmonary bypass. Methods Patients undergoing coronary artery bypass grafting, valve replacement surgery, or both were randomly assigned to receive either standard 1-g dosing with vancomycin before and after cardiopulmonary bypass or a single weight-based 20-mg/kg dose before surgery. The primary outcome was the percentage of time plasma concentrations were greater than 15 μg/mL during cardiopulmonary bypass and at surgical closure. Secondary outcomes included concentration of vancomycin in endothoracic tissue after vancomycin infusion, average time patients had vancomycin concentrations greater than 15 μg/mL, and vancomycin plasma and tissue pharmacokinetic parameters. Results Baseline characteristics were similar between the study dosing group (n = 10) and the standard dosing group (n = 10). From postinfusion to end of bypass, the median percentage of time vancomycin concentrations remained greater than 15 μg/mL was 100% (interquartile range [IQR], 72.6%-100%) for weight-based dosing versus 43.7% (IQR, 28.7%-53.4%) for standard dosing ( P = .0005). From postinfusion to surgical closure, the percentage of time vancomycin concentrations remained greater than 15 μg/mL was significantly higher in the weight-based group (100% [IQR, 58.3%-100%] vs 34.6% [IQR, 25.3%-41.6%]; P = .0005). Weight-based dosing increased calculated time with vancomycin concentrations greater than 15 μg/mL and resulted in higher endothoracic tissue vancomycin concentrations. Conclusions Weight-based vancomycin dosing before coronary artery bypass grafting or valve replacement results in vancomycin concentrations greater than 15 μg/mL consistently more than does standard 1-g dosing.