Identification of the caffeine to trimethyluric acid ratio as a dietary biomarker to characterise variability in cytochrome P450 3A activity

Purpose Cytochrome P450(CYP) 3A plays an important role in the metabolism of many clinically used drugs and exhibits substantial between-subject variability (BSV) in activity. Current methods to assess variability in CYP3Aactivity have limitations and there remains a need for a minimally invasive clinically translatable strategy to define CYP3Aactivity. The purpose of this study was to evaluate the potential for a caffeine metabolic ratio to describe variability in CYP3Aactivity.