Modafinil acid is a metabolite of modafinil, a wake-promoting agent for oral administration. Orally administered modafinil is extensively biotransformed in the liver to the inactive metabolites modafinil acid and modafinil sulphone, before being eliminated primarily in the urine (elimination half-life 9 to 14 hours). Modafinil acid was the major urinary metabolite, which accounted for 35% to 60% of the dose. Two major metabolites of modafinil, modafinil acid, and modafinil sulfone, do not appear to contribute to the CNS-activating properties of modafinil.

Lithocholic acid (LCA) is a secondary bile acid that is formed in the intestine by the bacteria and can activate the pregnane X and the vitamin D receptors. In humans, elevated levels of LCA are found in patients suffering from the chronic cholestatic liver disease. Whereas in normal colonic epithelium lithocholic acid promotes apoptosis, it has been shown to possess anti-tumor effect in human neuroblastoma cell lines. In addition, was proposed, that LCA could kill cancer cells and increase the longevity of non-cancerous cells by causing quite opposite effects on the same kind of mitochondria-confined processes in these two different cell types.