Urinary phenylacetylglutamine (U-PAGN) concentration as biomarker for adherence in patients with urea cycle disorders (UCD) treated with glycerol phenylbutyrate

Urinary phenylacetylglutamine (U-PAGN) concentrations in spot urine samples were analyzed as a dosing biomarker during glycerol phenylbutyrate (GPB) dosing in 68 healthy adults and 66 adult and pediatric patients with urea cycle disorders who participated in GPB clinical trials. Age- and body surface area (BSA)-specific 25th percentile cutoff points for spot U-PAGN concentrations (<~9000μg/mL for <2years old patients, <7000μg/mL for >2years with BSA ≤1.3m2, and <~5000μg/mL for >2years of age with BSA >1.3m2) were determined as an approach to identify patients for whom increased dosing and/or adherence to prescribed dosing should be assessed.