|Injectable (intravenous injection or infusion, intrathecal, or subcutaneously)|
|ATC code||L01BC01 (WHO)|
|Biological half-life||biphasic: 10 min, 1–3 hr|
|PDB ligand ID||AR3 (PDBe, RCSB PDB)|
|Chemical and physical data|
|Molar mass||243.217 g/mol|
|3D model (Jmol)||Interactive image|
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.
It is on the World Health Organization's List of Essential Medicines, a list of the most important medication needed in a basic health system.
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. Therefore, ara-C is not a useful antiviral agent in humans because of its toxic profile and actually it is used mainly for the chemotherapy of hematologic cancers.
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.
When used in protocols designated as high dose, cytarabine can cause cerebral and cerebellar dysfunction, ocular toxicity, pulmonary toxicity, severe GI ulceration and peripheral neuropathy (rare).
To prevent the side effects and improve the therapeutic efficiency, various derivatives of these drugs (including amino acid, peptide, fatty acid and phosphates) have been evaluated, as well as different delivery systems.
Mechanism of action
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.
- Tarabine PFS (Pfizer)
- Depocyt (longer-lasting liposomal formulation)
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