Trifluridine-13C,15N2 is the 13C and 15N labeled Trifluridine[1]. 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[2].