Comparing Two Vancomycin Loading Dose Regimens in Patients With Obesity: A Single-Center Prospective Clinical Trial.

Background: Obesity can significantly influence the pharmacokinetics of several medications, including vancomycin. Consequently, specialized dosing strategies may be required to ensure efficacy and safety in patients with obesity (PwO) requiring treatment with vancomycin. This single-center, prospective study evaluated two vancomycin loading dose regimens in PwO, comparing serum vancomycin concentrations, adverse events, and the impact on renal function.

Methods: Adult patients weighing over 100 kg were randomized into two study groups. A 20 mg/kg loading dose of vancomycin was administered to both groups, with one group restricted to a maximum dose of 2000 mg (n=33) and the other group receiving up to 4000 mg (n=34).

Results: Patients receiving the 4000 mg maximal dose achieved significantly higher median vancomycin concentrations at the initial trough (9.1 mg/L vs. 11.3 mg/L, p=0.0497), mean concentrations at the 7.5-hour interval trough (14.4 mg/L vs. 17.1 mg/L, p=0.0151), and mean concentrations at the post-load peak (23.9 mg/L vs. 30.9 mg/L, p=0.0023), without a corresponding increase in adverse renal outcomes, hospital length of stay, or mortality as compared with the 2000 mg maximum dose group.

Conclusions: The study's findings demonstrate that higher vancomycin doses in PwO are safely tolerated and do not result in short-term adverse effects on renal function. This study helps us better understand vancomycin pharmacotherapy in PwO, supporting the need for further research to refine dosing guidelines for these patients.