Materials and non-invasive methods are provided for determining a subject's present drug metabolic capacity by assessing a biofluid sample taken from the subject following administration of a compound and identifying phenotypic variations in activity of one or more drug absorption, distribution, metabolism and excretion (ADME) enzymes extracted from extracellular vesicles (EVs) in the biofluid sample. Additional materials and methods are provided for determining compound (e.g., drug) efficacy and dose ranging, either in a subject or in a treatment cohort, by quantifying level of expression of such ADME enzymes EVs selectively isolated from biofluid.