Roxadustat-d5 is intended for use as an internal standard for the quantification of roxadustat by GC- or LC-MS. Roxadustat is an inhibitor of hypoxia-inducible factor prolyl hydroxylase (HIF-PH; IC50s = 1.4, 1.26, and 1.32 µM for HIF-PH1, HIF-PH2, and HIF-PH3, respectively). It is selective for HIF-PH over other 2-oxoglutarate-dependent dioxygenases, including lysine-specific demethylase 5A (KDM5A), KDM5B, -5C, -5D, and -6B (IC50s = >100 µM for all). Roxadustat (10-200 µM) stabilizes HIF-1α and HIF-2α in Hep3B hepatocellular carcinoma cells. It increases levels of secreted erythropoietin in Hep3B cells in a concentration-dependent manner and increases erythropoiesis in rats when administered at doses of 25 and 50 mg/kg. Roxadustat reverses anemia in a rat model of chronic inflammation induced by peptidoglycan-polysaccharide, as well as a rat model of chronic kidney disease induced by 5/6 nephrectomy. It reduces tumor growth and increases survival in a murine Lewis lung carcin......