Tofacitinib-d3 (citrate) is deuterium labeled Tofacitinib (citrate). Tofacitinib citrate is an orally available JAK1/2/3 inhibitor with IC50s of 1, 20, and 112 nM, respectively. Tofacitinib citrate has antibacterial, antifungal and antiviral activities.