Human cytochrome P450 (CYP450) enzymes are responsible for much of the variability in response to drugs and other xenobiotics. The new field of pharmacogenetics is aimed at identifying sources of genetic variability underlying response to drugs. Within the field of investigation, CYP450 enzymes have been implicated in much of the literature. Of the pharmacogenomic biomarker information currently in drug product information labeling, CYP450 based pharmacogenetic biomarkers represent the largest biomarker group. After a subject ingests a cocktail of safe, over the counter drugs, we measure the parent drug to metabolite. We aim to turn the cocktail into a single oral tablet which may be patented as a diagnostic.