title: Physiologic disposition of cytosine arabinoside and its derivatives in man.
abstract: Enzymatic and clinical pharmacologic studies indicate that 2,2'-anhydro-1-beta-D-arabinofuranosyl-5-fluorocytosine (AAFC) is relatively resistant to enzymatic deamination and is not phosphorylated but slowly releases 1-beta-D-arabinofuranosyl-5-fluorocytosine. The latter is deaminated rapidly to 1-beta-D-arabinofuranosyl-5-fluorouracil. After iv injection of labeled cytosine arabinoside (Ara-C), 2,2'-anhydro-1-beta-D-arabinofuranosylcytosine, and AAFC into patients, radioactivity appears in substantial amounts and persists for a prolonged time in the saliva. AAFC slowly penetrates into the cerebrospinal fluid, reaches significant levels, and is retained there for a long time. Ara-C, due to rapid deamination in plasma, does not provide sustained levels of Ara-C in the cerebrospinal fluid. It is likely that this difference between AAFC and Ara-C is due to reduced polarity of the former compound.
mesh_terms: D000284:Administration, Oral; D003561:Cytarabine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000378:metabolism*; D003641:Deamination; D003841:Deoxycytidine; D006801:Humans; D066298:In Vitro Techniques; D007275:Injections, Intravenous; D009374:Neoplasms, Experimental / Q000201:enzymology; D010770:Phosphotransferases / Q000378:metabolism; D013997:Time Factors
chemical_list: D003561:Cytarabine; D003841:Deoxycytidine; D010770:Phosphotransferases