DOSAGE AND ADMINISTRATION
Cytarabine Injection 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, subcutaneously, or intrathecally (preservative free preparation only).
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 anti-cancer drugs is 100 mg/m2/day by continuous intravenous infusion (Days 1-7) or 100 mg/m2 intravenous 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
Cytarabine injection 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 injection given intrathecally may cause systemic toxicity and careful monitoring of the hematopoietic system is indicated. Modification 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 injection.
When cytarabine injection is administered both intrathecally and intravenously within a few days, there is an increased risk of spinal cord toxicity, however, in serious life-threatening disease, concurrent use of intravenous and intrathecal Cytarabine Injection is left to the discretion of the treating physician.
Focal leukemic involvement of the central nervous system may not respond to intrathecal cytarabine injection and may better be treated with radiotherapy.
Chemical Stability of Infusion Solutions
Chemical stability studies were performed by ultraviolet assay on Cytarabine Injection in infusion solutions. These studies showed that when Cytarabine Injection was added to Water for Injection, 5% Dextrose in Water or Sodium Chloride Injection, 94 to 96 percent of the cytarabine was present after 192 hours storage at room temperature.
Parenteral drugs should be inspected visually for particulate matter and discoloration, prior to administration, whenever solution and container permit. If a precipitate has formed as a result of exposure to low temperatures, redissolve by warming up to 55°C for no longer than 30 minutes, under dry heat conditions, and shake until the precipitate has dissolved. Allow to cool prior to use.