Tioguanine (INN), formerly Thioguanine (BAN), is a drug that's used in the treatment of cancer. It belongs to the family of drugs called antimetabolites. It is a guanine analog. Its principal use is in acute leukaemias and chronic myeloid leukaemia. Pharmacology As a guanine analogue, it's transformed inside the cell into to 6-thioguanilyic acid (TGMP), which, by pseudofeedback interference with purine biosynthesis, interferes with the synthesis of guanine nucleotides. Some of its activity may… (More on Tioguanine)