Cytarabine is a pyrimidine nucleoside in which cytosine is attached to D-arabinofuranose via a beta-N1-glycosidic bond. Used mainly in the treatment of leukaemia, especially acute non-lymphoblastic leukaemia, cytarabine is an antimetabolite antineoplastic agent that inhibits the synthesis of DNA. It also has antiviral and immunosuppressant properties. It has a role as an antiviral agent, an antimetabolite, an antineoplastic agent and an immunosuppressive agent.

2'-deoxycytidine is a pyrimidine 2'-deoxyribonucleoside having cytosine as the nucleobase. It has a role as a mouse metabolite, a Saccharomyces cerevisiae metabolite, an Escherichia coli metabolite and a human metabolite. It is functionally related to a cytosine.