Leflunomide is a monocarboxylic acid amide obtained by formal condensation of the carboxy group of 5-methyl-1,2-oxazole-4-carboxylic acid with the anilino group of 4-(trifluoromethyl)aniline. The prodrug of teriflunomide. It has a role as a non-steroidal anti-inflammatory drug, an antineoplastic agent, an antiparasitic agent, an EC 1.3.98.1 [dihydroorotate oxidase (fumarate)] inhibitor, a hepatotoxic agent, a prodrug, a pyrimidine synthesis inhibitor, an immunosuppressive agent, an EC 3.1.3.16 (phosphoprotein phosphatase) inhibitor and a tyrosine kinase inhibitor. It is a monocarboxylic acid amide, a member of isoxazoles and a member of (trifluoromethyl)benzenes.