All are alkylating agents, except:

ANTICANCER DRUGS: A. Drugs acting directly on cells (Cytotoxic drugs) 1. Alkylating agents Nitrogen mustards Mechlorethamine (Mustine HCl) Cyclophosphamide, Ifosfamide, Chlorambucil, Melphalan Antimetabolites >Folate antagonist:Methotrexate (Mtx) >Purine antagonist:6-Mercaptopurine (6-MP), 6-Thioguanine (6-TG), Azathioprine, Fludarabine >Pyrimidine antagonists:5-Fluorouracil (5-FU), Cytarabine. Fluorourri ul U, -FU) is conveed in the body to the corresponding nucleotide 5-fluoro-2-deoxyuridine monophosphate, which inhibits thymidylate synthase and blocks the conversion of deoxyuridilic acid to deoxythymidylic acid. Selective failure of DNA synthesis occurs due to non-availability of thymidylate: thymidine can paially reverse its toxicity. Fluorouracil itself gets incorporated into nucleic acids and this may contribute to its toxicity. Even resting cells are affected, though rapidly multiplying ones are more susceptible. It has been paicularly used for many solid tumours-breast, colon, urinary bladder, liver, etc. Topical application in cutaneous basal cell carcinoma has yielded gratifying results. ESSENTIALS OF MEDICAL PHARMACOLOGY K.D.TRIPATHI SIXTH EDITION PAGE NO:824