Baricitinib is used to treat arthritis, both alone and in combination with methotrexate. The compound is a reversible inhibitor of Janus kinase enzymes. Baricinitib was approved for use in the EU in 2017, but the USFDA has refused to approve the drug, citing concerns over safety and dosage. Atoms are represented as spheres and are colour-coded: carbon (black), hydrogen (white), nitrogen (blue), oxygen (red) and sulphur (yellow).