Molecular Formula: C₁₂H₉F₃N₂O₂ 
Synonyms: 4-Isoxazolecarboxamide, 5-methyl-N-(4-(trifluoromethyl)phenyl)-; N-(4-Trifluoromethylphenyl)-5-methylisoxazole-4-carboxamide; Leflunomidum [INN-Latin]; sell leflunomide; 5-methyl-N-[4-(trifluoromethyl)phenyl]oxazole-4-carboxamide; 5-Methylisoxazole-4-(4-trifluoromethyl) carboxanilide; Leflunamide; Isoxazole-4-carboxamide, 5-methyl-N-[4-(trifluoromethyl)phenyl]-; 5-Methylisoxazole-4-carboxylic acid (4-trifluoromethyl)anilide; Arava; Leflunomida [INN-Spanish];
Appearance: off white crystalline solid
Molecular Weight: 270.21
Density: 1.392 g/cm3
Boiling Point: 289.3 °C at 760 mmHg
Melting Point: 163-168℃
Flash Point: 128.8 °C
Storage Temperature: 2-8°C
Solubility: Insoluble
Biological Activity: Immunosuppressant agent. In vitro the active metabolite A77 1726 (RS-61980) inhibits dihydroorotate dehydrogenase (K i = 2.7 μ M) and de novo pyrimidine synthesis in T-cells; blocks lymphocyte cell cycle progression and proliferation. A77 1726 also inhibits anti-CD3/CD28-induced cytokine production in PBMC cells (IC 50 = 21-27 μ g/ml). In vivo reduces inflammation in several animal models of autoimmune disease, arthritis, asthma and graft rejection.
Usage: An immunosuppressive. Inhibits T and B cell proliferation. Activity is attributed mainly to its metabolite, a malononitrile derivative, which is beleived to inhibit dihydroorotate dehydrogenase as well as several protein tyrosine kinases. Therape