Baricitinib is a pyrrolopyrimidine that is 7H-pyrrolo[2,3-d]pyrimidine substituted by a 1-[3-(cyanomethyl)-1-(ethanesulfonyl)azetidin-3-yl]-1H-pyrazol-4-yl group at position 5. It is an FDA approved selective Janus Kinase 1 and 2 (JAK1 and JAK2) inhibitor used for the treatment of rheumatoid arthritis. It has a role as an antirheumatic drug, an EC 2.7.10.2 (non-specific protein-tyrosine kinase) inhibitor, an anti-inflammatory agent, an immunosuppressive agent and an antiviral agent. It is a pyrrolopyrimidine, a member of pyrazoles, a member of azetidines, a sulfonamide and a nitrile.