A molecular model of leflunomide (a.k.a. Arava), an antirheumatic drug used to treat moderate to severe rheumatoid arthritis and psoriatic arthritis. Leflunomide helps to slow the progression of diseases like rheumatoid arthritis, by interfering with the cell cycle of autoimmune lymphocytes which damage joints, as well as provide anti-inflammatory relief. Atoms are colored dark gray (carbon), light gray (hydrogen), red (oxygen), blue (nitrogen) and green (fluorine).