About Cyclophosphamide A nitrogen mustard alkylating agent, Oxazophorines group, Antineoplastic , Antirheumatic.. Mechanism of Action of Cyclophosphamide This alkylating drug produces the death of cancer cells by an alkylation mechanism. This is a pro drug which converted to alkyl groups (aldophosphamide and phospharamide mustard) in the liver. These groups can cyclize in an aqueous environment to form a highly electrophilic "immonium ion" that can covalently bind to the N-7 nitrogen of guanine in DNA, which is a major site of action. Consequently it produce a cross linking of DNA when both alkyl groups react pairs of guanine residues in DNA. This breaks the DNA sequence, which results cell death. These agents can also react chemically with other cellular components containing nucleophilic group i.e. sulf hydryl, amino, hydroxyl, carboxyl and phosphate groups. Its action is cell cyclic and non specific. So it acts on the divided as well as resting cells. It has prominent immunosup