5-Methylisoxazole-4-Carboxylic Acid CAS 42831-50-5 Leflunomide Intermediate Purity >99.0% (HPLC)

5-Methylisoxazole-4-Carboxylic Acid (CAS: 42831-50-5) is an intermediate for synthesis of Leflunomide (CAS: 75706-12-6). Leflunomide is a kind of isoxazole immunosuppressive drugs with anti-proliferative activity, modern pharmacology classifies this product as antipyretic, analgesic and anti-inflammatory drugs. This product can be rapidly converted to the active metabolites  and play a role by the liver and intestinal cytoplasm and microsomes, its; main mechanism is during DNA synthesis, inhibiting a key enzyme-DHODH (DHODH) activity, so that the nucleotides within the B lymphocyte are depleted, it terminates the biosynthesis of DNA and RNA, the cells can not enter s phase, and ultimately can not proliferate, resulting in anti-rheumatic effects, it is suitable for the treatment of adults with active rheumatoid arthritis, ankylosing spondylitis, it can slow bone destruction, alleviate the symptoms and signs. In addition, leflunomide can also inhibit the tyrosine kinase activity, thereby inhibiting proliferation of T cell, B cell  and non-immune cells, but it can also, by biosynthesis inhibition of cyclooxygenase-2 (COX2), inhibit prostaglandin synthesis and exert anti-inflammatory effects and inhibit mast cells and basophils histamine release. When  this product is used in organ transplant patients, the dose adjustment is difficult, it is mainly used to treat rheumatoid arthritis and other autoimmune diseases.