DOSAGE AND ADMINISTRATION
Cytarabine is not active orally. The schedule and method of administration varies with the program of therapy to be used. Cytarabine Injection may be given by intravenous infusion or injection or subcutaneously. Thrombophlebitis has occurred at the site of drug injection or infusion in some patients, and rarely patients have noted pain and inflammation at subcutaneous injection sites. In most instances, however, the drug has been well tolerated.
Patients can tolerate higher total doses when they receive the drug by rapid intravenous injection as compared with slow infusion. This phenomenon is related to the drug’s rapid inactivation and brief exposure of susceptible normal and neoplastic cells to significant levels after rapid injection. Normal and neoplastic cells seem to respond in somewhat parallel fashion to these different modes of administration and no clear-cut clinical advantage has been demonstrated for either.
In the induction therapy of acute non-lymphocytic leukemia, the usual cytarabine dose in combination with other anticancer drugs is 100 mg/m2/day by continuous IV infusion (Days 1-7) or 100 mg/m2 IV every 12 hours (Days 1-7).
The literature should be consulted for the current recommendations for use in acute lymphocytic leukemia.
Intrathecal Use in Meningeal Leukemia: DO NOT USE CYTARABINE INJECTION (which contains benzyl alcohol) INTRATHECALLY.
The following dosage information regarding intrathecal use is included for informational purposes only.
Cytarabine has been used intrathecally in acute leukemia in doses ranging from 5 mg/m2 to 75 mg/m2 of body surface area. The frequency of administration varied from once a day for 4 days to once every 4 days. The most frequently used dose was 30 mg/m2 every 4 days until cerebrospinal fluid findings were normal, followed by one additional treatment. The dosage schedule is usually governed by the type and severity of central nervous system manifestations and the response to previous therapy.
Cytarabine given intrathecally may cause systemic toxicity and careful monitoring of the hemopoietic system is indicated. Modifications of other anti-leukemia therapy may be necessary. Major toxicity is rare. The most frequently reported reactions after intrathecal administration were nausea, vomiting and fever; these reactions are mild and self-limiting. Paraplegia has been reported. Necrotizing leukoencephalopathy occurred in 5 children; these patients had also been treated with intrathecal methotrexate and hydrocortisone, as well as by central nervous system radiation. Isolated neurotoxicity has been reported. Blindness occurred in two patients in remission whose treatment had consisted of combination systemic chemotherapy, prophylactic central nervous system radiation and intrathecal cytarabine.
When cytarabine is administered both intrathecally and intravenously within a few days, there is an increased risk of spinal cord toxicity, however, in serious lifethreatening disease, concurrent use of intravenous and intrathecal cytarabine is left to the discretion of the treating physician.
Focal leukemic involvement of the central nervous system may not respond to intrathecal cytarabine and may be better treated with radiotherapy.
Chemical Stability in Infusion Solutions
Chemical stability studies were performed by a stability indicating HPLC assay on Cytarabine Injection in infusion solutions. These studies showed that when Cytarabine Injection was diluted with Water for Injection, 5% Dextrose Injection or Sodium Chloride Injection, 97-100% of the cytarabine was still present after 8 days storage at room temperature.
This chemical stability information in no way indicates that it would be acceptable practice to infuse a cytarabine admixture well after the preparation time. Good professional practice suggests that administration of an admixture should be as soon after preparation as feasible.
Parenteral drugs should be inspected visually for particulate matter and discoloration, prior to administration, whenever solution and container permit.
Handling and Disposal
Procedures for proper handling and disposal of anti-cancer drugs should be considered. Several guidelines on this subject have been published.1-7 There is no general agreement that all of the procedures in the guidelines are necessary or appropriate.