Abstract: This application relates to a homogeneous biorelevant composition for preparing fasted state biorelevant media having a surface tension between 25 mN/m and 50 mN/m for simulating fasted state gastric and fasted state upper small intestinal fluids of mammalian species, especially humans, dogs, etc. comprising at least one bile salt, eg. sodium taurocholate or sodium taurodeoxycholate; at least one phospholipid, especially 60-99 wt % phosphatidylcholine (PC), enzyme digested diacylphospholipids containing 50-90 wt % of monoacyl-PC; or mixtures thereof; and at least one fatty acid or monovalent salt of the fatty acid, such as sodium oleate. The application also relates to an aqueous biorelevant media composed of surfactants occurring in the gastrointestinal tract of mammals, in particular when prepared from above homogeneous biorelevant composition.