An Open-Label, Single-Dose, Pharmacokinetic Study of Vancomycin Dosed by Weight or Kidney Function in Adults With Obesity

This prospective, dosing group-randomized, single-dose pharmacokinetic study aims to evaluate vancomycin dosing in healthy obese participants across three BMI and two kidney function categories. Twenty-four participants will be enrolled, stratified by BMI (30-34.9 kg/m², 35-39.9 kg/m², ≥40 kg/m²) and creatinine clearance using dosing weight (CLcr_dw 60-119 mL/min or ≥120 mL/min). Twenty-four participants will be randomized (1:1) into a standard of care vancomycin group (Control) or a kidney function based group (Test). The study will include physical exams, medical history, and laboratory evaluations. Vancomycin doses will be administered based on weight or kidney function after pretreatment with antihistamines. Pharmacokinetic data will be collected through blood and urine samples at specific time points. Body composition measurements will be performed using DEXA and through anthropometric methods. Serum cystatin C concentrations will also be measured. Data analysis will include fitting vancomycin concentration-time data using a 2-compartment linear model to estimate area under the curve (AUC). Group comparisons for AUC target attainment (400-600 h*mg/L) will be performed using Fisher's Exact Test. Additionally, the study will test if the investigators can reduce the standard two-sample method for AUC estimation to a single sample. Different models of estimated glomerular filtration rate (eGFR) will be compared as predictors of vancomycin clearance (CL). This study will provide insights into optimizing vancomycin dosing in obese individuals with varying kidney function, potentially improving therapeutic drug monitoring strategies.