Source: Medicines & Healthcare Products Regulatory Agency (GB) Revision Year: 2021 Publisher: Hospira UK Ltd, Horizon, Honey Lane, Hurley, Maidenhead, SL6 6RJ, United Kingdom
Pharmacotherapeutic group: Pyrimidine analogues
ATC code: L01BC01
Cytarabine (ARA-C) is metabolised in vivo to ARA-CTP phosphorylated compound. This competitively inhibits DNA polymerase and may also inhibit certain acid kinase enzymes. Primarily the drug acts as a false nucleoside and competes for enzymes involved in the conversion of cytidine nucleotide to deoxycytidine nucleotide and also incorporation into the DNA.
Cytarabine has no effect on non proliferating cells nor on proliferating cells unless in the S phase. It is a cell cycle specific antineoplastic drug.
Oral administration is ineffective due to rapid deamination in the gut. Cytidine deaminase is concentrated in the liver and intravenous doses show biphasic elimination with half lifes of approximately 10 minutes and 1-3 hours.
After 24 hours 80% of a dose has been eliminated either as the inactive metabolite or as the unchanged cytarabine, mostly in urine but some in bile.
CSF levels of 50% of plasma levels are achieved with intravenous infusion. Intrathecal dosing results in slower elimination (T1/2 2-11 hours).
Cytarabine is rapidly and widely distributed into tissues, crosses the blood brain barrier and also the placenta.
There is no pre-clinical data of relevance to the prescriber which are additional to that already included in other sections of the SPC.
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