Process for preparing leflunomide form I

摘要

New leflunomide Form III is disclosed, along with processes for preparing it. The present invention also provides an economic process for preparing leflunomide Form II and a process for preparing leflunomide Form I from leflunomide Form III. Pharmaceutical compositions and dosage forms containing the new form and methods of using them for the treatment of rheumatoid arthritis are also disclosed.