|Systematic (IUPAC) name|
|4-amino-1-[(2R,3S,4R,5R)-3,4-dihydroxy-5- (hydroxymethyl)oxolan-2-yl] pyrimidin-2-one|
|Pregnancy cat.||D (AU) D (US)|
|Legal status||℞ Prescription only|
|Routes||Injectable (intravenous injection or infusion, intrathecal, or subcutaneously)|
|Half-life||biphasic: 10 min, 1-3 hr|
|Mol. mass||243.217 g/mol|
| (what is this?)
Cytarabine or cytosine arabinoside (Cytosar-U or Depocyt) is a chemotherapy agent used mainly in the treatment of cancers of white blood cells such as acute myeloid leukemia (AML) and non-Hodgkin lymphoma. It is also known as Ara-C (Arabinofuranosyl Cytidine). It kills cancer cells by interfering with DNA synthesis.
It is called cytosine arabinoside because it combines a cytosine base with an arabinose sugar. Cytosine normally combines with a different sugar, deoxyribose, to form deoxycytidine, a component of DNA. Certain sponges, where it was originally found, use arabinoside sugars to form a different compound (not part of DNA). Cytosine arabinoside is similar enough to human cytosine deoxyribose (deoxycytidine) to be incorporated into human DNA, but different enough that it kills the cell. This mechanism is used to kill cancer cells. Cytarabine is the first of a series of cancer drugs that altered the sugar component of nucleosides. Other cancer drugs modify the base.
Cytosine arabinoside interferes with the synthesis of DNA. It is an antimetabolic agent with the chemical name of 1β-arabinofuranosylcytosine. Its mode of action is due to its rapid conversion into cytosine arabinoside triphosphate, which damages DNA when the cell cycle holds in the S phase (synthesis of DNA). Rapidly dividing cells, which require DNA replication for mitosis, are therefore most affected. Cytosine arabinoside also inhibits both DNA and RNA polymerases and nucleotide reductase enzymes needed for DNA synthesis.
Cytarabine is rapidly deaminated in the body into the inactive uracil derivative and therefore is often given by continuous intravenous infusion.
Clinical uses 
Cytarabine also possesses antiviral activity, and it has been used for the treatment of generalised herpesvirus infection. However, cytarabine is not very selective in this setting and causes bone marrow suppression and other severe side effects, so it is used mainly for the chemotherapy of hematologic cancers.
Side effects 
One of the unique toxicities of cytarabine is cerebellar toxicity when given in high doses, which may lead to ataxia. Cytarabine may cause granulocytopenia and other impaired body defenses, which may lead to infection, and thrombocytopenia, which may lead to hemorrhage.
Toxicity: leukopenia, thrombocytopenia, anemia, GI disturbances, stomatitis, conjunctivitis, pneumonitis, fever, and dermatitis, Palmar-Plantar Erythrodysesthesia. Rarely, myelopathy has been reported after high dose or frequent intrathecal Ara-C administration.
To prevent the side effects and improve the therapeutic efficiency, various derivatives of this drugs (including amino acid, peptide, fatty acid and phosphates) have been evaluated, as well as different delivery systems.
Brand names 
- Tarabine PFS (Pfizer)
- Depocyt (longer-lasting liposomal formulation)
- Wang WS, Tzeng CH, Chiou TJ, et al. (June 1997). "High-dose cytarabine and mitoxantrone as salvage therapy for refractory non-Hodgkin's lymphoma". Jpn. J. Clin. Oncol. 27 (3): 154–7. doi:10.1093/jjco/27.3.154. PMID 9255269.[dead link]
- Ogbomo H, Michaelis M, Klassert D, Doerr HW, Cinatl J (December 2008). "Resistance to cytarabine induces the up-regulation of NKG2D ligands and enhances natural killer cell lysis of leukemic cells". Neoplasia 10 (12): 1402–10. PMC 2586691. PMID 19048119.
- Feist, Patty (April 2005). "A Tale from the Sea to Ara C".
- Sneader, Walter (2005). Drug discovery: a history. New York: Wiley. p. 258. ISBN 0-471-89979-8.
- Perry, Michael J. (2008). The Chemotherapy source book. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. p. 80. ISBN 0-7817-7328-8.
- Lemke, Thomas L.; Williams, David H.; Foye, William O. (2002). Foye's principles of medicinal chemistry. Hagerstwon, MD: Lippincott Williams & Wilkins. p. 963. ISBN 0-683-30737-1.
- Pigneux A, Perreau V, Jourdan E, et al. (October 2007). "Adding lomustine to idarubicin and cytarabine for induction chemotherapy in older patients with acute myeloid leukemia: the BGMT 95 trial results". Haematologica 92 (10): 1327–34. doi:10.3324/haematol.11068. PMID 18024370.
- Watterson J, Toogood I, Nieder M, et al. (December 1994). "Excessive spinal cord toxicity from intensive central nervous system-directed therapies". Cancer 74 (11): 3034–41. doi:10.1002/1097-0142(19941201)74:11<3034::AID-CNCR2820741122>3.0.CO;2-O. PMID 7954266.
- Chhikara BS, Parang K (2010). "Development of cytarabine prodrugs and delivery systems for leukemia treatment". Expert Opinion on Drug Delivery 7 (12): 1399–1414. doi:10.1517/17425247.2010.527330.
- MedlinePlus page on cytarabine
- ADAP drugs page on cytarabine
- BC Cancer network page on cytarabine
- Chembank entry
- Sea to Ara C An essay on the history of cytarabine.