Excretion of cytosine arabinoside in saliva after its administration at high doses

High-dose cytosine arabinoside (cytarabine) is widely used, either alone or in combination with other chemotherapeutic agents, for the treatment of refractory hematological malignancies. Its pharmacology in plasma and cerebrospinal fluid has been extensively examined. In this study, we measured the concentration of cytarabine in saliva of nine patients with hematological malignancies who received high-dose cytarabine. Cytarabine at a dose of 3 g/m was administered i.v. over 2 h. Saliva samples were collected before initiating cytarabine infusion, within 15 min after the completion of infusion and 2 or 4 h after infusion. The concentration of cytarabine was measured by HPLC methods. All nine patients showed a detectable level of cytarabine in saliva within 15 min after the completion of infusion (0.58±0.48 μg/ml), which was equivalent to 5% of its plasma concentration; however, the drug was no longer detectable in saliva thereafter. These findings suggest that cytarabine is excreted in saliva during and shortly after its administration at a high dose.