Trifluridine

Trifluridine is a pyrimidine nucleoside analog. After entering the cell, it is progressively phosphorylated by enzymes such as thymidine kinase into active monophosphate and triphosphate derivatives. The monophosphate form of trifluridine inhibits thymidylate synthase, blocking the formation of dTMP and causing a shortage of thymidylate required for DNA synthesis. The triphosphate form can be directly incorporated into newly synthesized DNA, resulting in DNA structural instability and ultimately causing cells or viruses to lose their capacity for replication.