Leflunomide is a drug used to treat rheumatoid and psoriatic arthritis. It functions by blocking dihydroorotate dehydrogenase, a key enzyme in de novo pyrimidine synthesis. Blocking nucleotide synthesis leads to a suppression of all rapidly dividing cells, including lymphocytes. In this way, leflunomide is an anti-inflammatory drug that can be used to treat and improve the course of autoimmune diseases like rheumatoid and psoriatic arthritis.  Given its effects on rapidly dividing cells, leflunomide can cause a host of side effects, including diarrhea, hepatotoxicity, hair loss, immunosuppression, and teratogenicity in pregnant women.

Key Points

  • Leflunomide
    • Mechanism
      • Inhibits dihydroorotate dehydrogenase
        • Important in De Novo Pyrimidine Synthesis (link to scene)
        • Suppresses T-cell proliferation
    • Clinical Use
      • Anti-inflammatory agent
        • Used mainly as a disease-modifying antirheumatic drug (DMARD)
        • E.g. rheumatoid arthritis, psoriatic arthritis
    • Adverse Effects
      • Diarrhea
      • Hypertension
      • Hepatotoxicity
      • Teratogenicity