Fluorouracil

Mechanism of action

• Anti-metabolite

• Inhibits DNA replication

• Thymidylate synthase (TS) inhibitor.

  • Interrupting the action of this enzyme blocks synthesis of the pyrimidine thymidylate (dTMP), which is a nucleotide required for DNA replication.
  • Thymidylate synthase methylates deoxyuridine monophosphate (dUMP) to form thymidine monophosphate (dTMP).
  • Administration of 5-FU causes a scarcity in dTMP, so rapidly dividing cancerous cells undergo cell death via thymineless death.

• 5-Fluorouracil (Efudix)

  • Twice daily for 6 weeks.
  • Blocks incorporation of thymidine into DNA
  • Previously extensively used, but now Aldara is felt to be more effective