Trifluridine- 13 C, 15 N 2 is the 13 C and 15 N labeled Trifluridine. Trifluridine (Trifluorothymidine;5-Trifluorothymidine;TFT) is an irreversible thymidylate synthase inhibitor , and thereby suppresses DNA synthesis. Trifluridine is an antiviral agent for herpes simplex virus ( HSV ) infection. Trifluorothymidine also has anti-orthopoxvirus activity.