The aim of this project is the validation of a phenotyping cocktail of low dose probe drugs for the assessment of cytochrome P450 and P-gp activities by simple capillary blood sampling and dried blood spot (DBS) analysis. The cocktail consists of caffeine, bupropion, flurbiprofen, omeprazole, dextromethorphan, midazolam and fexofenadine for the simultaneous phenotyping of CYP1A2, CYP2B6, CYP2C9, CAP2C19, CYP2D6, CYP3A4 and P-gp, respectively.