A pyrimidine nucleoside analog that is used mainly in the treatment of Leukemia, especially acute non-Lymphoblastic Leukemia. Cytarabine is an antimetabolite antineoplastic agent that inhibits the synthesis of DNA. Its actions are specific for the S Phase of the Cell Cycle. It also has antiviral and immunosuppressant properties. (From Martindale, The Extra Pharmacopoeia, 30th ed, p472)