Overview
Cytarabine is a drug used to treat certain cancers, most notably leukemia.
Chemically, it is a pyrimidine analog that functions inside cells as an antimetabolite. It kills cell undergoing DNA synthesis (S-phase) and, under certain conditions, blocking the progression of cells from the G1-phase to S-phase.
Intracellularly, it is converted into the 5'-triphosphate (ara-CTP), an active metabolite.
Its precise mechanism of action is uncertain, though it does appear to inhibit DNA polymerase and may become incorporated into DNA and RNA.
Cytarabine is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.
This drug is not approved for use in animals by the Food and Drug Administration but it is prescribed legally by veterinarians as an extra-label drug.
Brand Names and Other Names
This drug is registered for use in humans only.
Human formulations: Tarabine® (Adria), Cytarabine® (Faulding), Cytosar-U® (Gensia Sicor), and generic cytarabine.
Veterinary formulations: None
Uses of Cytarabine
Cytarabine may be used for the following conditions:
Lymphoreticular neoplasms
Myeloproliferative disease (leukemias)
CNS lymphoma
Granulomatous meningoencephalitis
Precautions and Side Effects
Cytarabine can cause severe side effects, including death, in some animals.
Cytarabine should not be used in animals with known hypersensitivity or allergy to the drug or in those with active meningeal infection.
Cytarabine may cause fetal harm and should probably be avoided in pregnant animals.
Myelosuppression occurs with cytarabine, leading to leucopenia. Anemia and thrombocytopenia may also occur.
Proper monitoring of blood work is essential with this drug. Peak myelosuppression occurs after about a week of treatment. Hyperuricemia may occur during treatment in human patients, so it may be prudent to check blood uric acid levels during treatment.
Drug Interactions
Cytarabine may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with cytarabine. Such interactions may include:
Cytarabine may decrease digoxin absorption and may have some negative interaction with gentamicin.
How Cytarabine is Supplied
Cytarabine is an injectable medication that comes in a 20mg/mL concentrations. It also is available as a powder for injection in 100mg, 500mg, 1g, and 2g in multidose vials (that is reconstituted with sterile 0.9% saline solution to make 20, 50, or 100mg/mL concentration).
Dosing Information
Medication should never be administered without first consulting your veterinarian.
The dosage prescribed may vary depending on the reason for prescribing.
The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse.
Cytarabine is frequently used as part of a multi-drug chemotherapeutic regimen. *Doses and routes of administration vary.*
In dogs, the usual dose is 100 mg/m2 subcutaneously, intramuscularly or intravenously once daily for 2 to 4 days, increasing to 150mg/m2 if well tolerated. Cancer suppression can be maintained with a combination of agents that may or may not include periodic treatment with cytarabine. Alternatively, 150mg/m2 for 5 days repeated for 3 consecutive weeks.
In cats, the usual dose is100 mg/m2 subcutaneously or intravenously once daily for 2 to 4 days; then 10 mg/m2, once daily for 2 weeks.
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