Which statement correctly describes Leflunomide?

• A. Leflunomide's brand name is Arava, and it is a prodrug that inhibits pyrimidine synthesis.
• B. Leflunomide brand Arava but it inhibits purine synthesis.
• C. It is a monoclonal antibody against TNF.
• D. It is a non-steroidal anti-inflammatory drug.

Answer: (C)

Leflunomide is a disease-modifying antirheumatic drug that works by blocking de novo pyrimidine synthesis. It is a prodrug (converted to the active teriflunomide) that inhibits dihydroorotate dehydrogenase, reducing production of pyrimidines and thereby limiting the proliferation of activated T and B lymphocytes. This mechanism underlies its use in rheumatoid arthritis. Its brand name is Arava. It is not a monoclonal antibody against TNF (that describes anti-TNF biologics like infliximab or adalimumab), and it is not an NSAID. It specifically targets pyrimidine synthesis, not purine synthesis.