Aubagio or teriflunomide, is a type of pyrimidine synthesis inhibitor. This drug is an oral medicine that inhibits the function of specific immune cells that have been implicated in multiple sclerosis. Aubagio can block a key enzyme needed by white blood cells which helps reduce the number of T and B immune cells that are active in patients with multiple sclerosis. Aubagio also hinders the production of immune messenger chemicals by T cells. Aubagio was approved by the FDA in 2012 for human use.