Cytosine Arabinoside Ara-C

Intraperitoneal administration of chemotherapeutic agents has been used for many years as a way of increasing the delivery of drugs to tumors (e.g., ovarian carcinoma) located in the peritoneal cavity (Markman, 1986 Howell and Zimra, 1988). Cisplatin (Casper et al., 1983 Markman et al., 1985), cytosine arabinoside (Ara-C) (King et al., 1984 Markman et al., 1985, 1986), and bleomycin (Markman et al., 1986) are examples of intraperitoneally administered drugs which were already successfully applied in clinical settings. 

As well as NONOates, other NO donors also showed anticancer activity independently. Sodium nitroprusside (SNP), a metal-NO complex, showed cytotoxic effects on the cells of some patients with malignant lymphoma (ML), acute myelocytic leukemia (AML) or chronic myelomonocytic leukemia (CMMoL), but not with multiple myeloma [109]. SNP and cytosine arabinoside (Ara-C) did not share the drug resistance. Interestingly, SNP had no effect on lymphocytes of healthy volunteers. These results suggest that SNP has an anti-tumor effect on human hematological malignant cells. 

There has been some concern expressed regarding the use of CSFs to treat MDS patients. Because these cytokines have proliferative activity, they have the potential to induce a leukaemic transformation in the malignant clone. However, the combined use of CSFs with cytotoxic drugs such as cytosine arabinoside (ara-C) appears promising. If leukaemic clones are induced to proliferate by the cytokine, then they are killed by ara-C as they enter the cell cycle. Other forms of differentiation therapy, such as treatment with retinoids, 1,25-dihydroxyvitamin D3 and interferons, have also been tested, but results have been variable. 

Cytarabine (cytosine arabinoside, ara-C, Cytosar-U) is an analogue of the pyrimidine nucleosides cytidine and deoxycytidine. It is one of the most active agents available for the treatment of acute myelogenous leukemia. Cytarabine kills cells in the S-phase of the cycle by competitively inhibiting DNA polymerase. The drug must... 

Cytarabine (cytosine arabinoside, ara-C) is an S phase-specific antimetabolite that is converted by deoxycytidine kinase to the 5 -mononucleotide (AraCMP). AraCMP is further metabolized to the triphosphate (AraCTP), which competitively inhibits DNA polymerase and results in blockade of DNA synthesis. Cytarabine is also incorporated into RNA and DNA. Incorporation into DNA leads to interference with chain elongation and defective ligation of fragments of newly synthesized... 

The distribution and disposition of a drug in the body result from a complex set of physiological processes and biochemical interactions. In principle, it is possible to describe these processes and interactions in mathematical terms and, if sufficient data are available, to predict the time course of drug and metabolite(s) in different species and at specific anatomic sites (15). A physiological pharmacokinetic model was developed to predict the deamination of cytosine arabinoside (ARA-C) in humans from enzyme parameters determined from homogenates of human tissue (16). ARA-C is converted to its inactive metabolite, uracil arabinoside (ARA-U) by cytidine deaminase, the activity of which varies substantially among tissues. 

The introduction of an azido substituent on the C-2 position of cytosine arabinoside (ara-C) (149) or adenosine arabinoside (ara-A) (154) has been found to confer favourable properties to these antimetabolites. Ara-C, one of the most effective drugs for the treatment of human acute myeloblastic leukaemia [176], is subject to rapid metabolic deamination, by deoxycytid-ine deaminase, to the inactive uridine derivative ara-U (152) Scheme 3.5), and the drug has a half-life of approximately 12 minutes in man [177]. Efforts to circumvent this problem by modifying the 2 -arah/ o-position led... 

L. R. Crane, R. Jackson, and V. 1. Avramis. DNA hypermethylation studies in CEM/O cells after treatment with therapeutic and sub-therapeutic concentrations of cytosine arabinoside (ARA-C). Proc. Am. Assoc. Cancer Res. 30 496 (1989) [abstr.]. 

Cytosine arabinoside (Ara-C) is an anticancer drug, and an example of host effects causing the need for large doses of drug to have a clinical effect far greater than would have been predicted from in vitro studies. What is the reason for this How is it overcome ... 

If the intent is to develop a complete a priori description, the pharmacokinetics must be included. Several relevant studies have been done for some of the commonly used cancer chemotherapeutic agents two are described here. The first is the folic acid antagonist, methotrexate (MTX) the second is cytosine arabinoside (ARA-C). Both are active against leukemia, which is of primary interest here. 

Kanno S, Shouji A, Hirata R, Asou K, Ishikawa M (2004) Effects of naringin on cytosine arabinoside (Ara-C)-induced cytotoxicity and apoptosis in P388 cells. Life Sci 75 353... 

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