Leflunomide

**Semantic type:** Organic Chemical|Pharmacologic Substance

**Definition:** A derivative of isoxazole used for its immunosuppressive and anti-inflammatory properties. As a prodrug, leflunomide is converted to an active metabolite, A77 1726, which blocks dihydroorotate dehydrogenase, a key enzyme of de novo pyrimidine synthesis, thereby preventing the expansion of activated T lymphocytes. This agent also inhibits various protein tyrosine kinases, such as protein kinase C (PKC), thereby inhibiting cell proliferation. (NCI04)

**Synonyms:** - 4-Isoxazolecarboxamide, 5-Methyl-N-(4-(trifluoromethyl)phenyl)- - Arava - LEFLUNOMIDE - SU101 - SU101 - leflunomide