Background The administration of triple intrathecal therapy with methotrexate, cytarabine and a corticosteroid for the prophylaxis and treatment of neoplastic cell infiltration in the central nervous system in hematological malignancies is a widespread practice. There is limited information available about its toxicity profile. Several factors related to intrathecal preparation can affect toxicity. Thus, it was decided to standardize intrathecal chemotherapy, trying to obtain the best toxicity profile. Objective To assess the toxicity of a standardized triple intrathecal chemotherapy in oncohematological pediatric patients and to establish risk factors of toxicity. Setting Oncohematological pediatric unit from a tertiary hospital in Spain. Methods Prospective, descriptive and observational study in which all the administrations of standardized triple intrathecal chemotherapy in pediatric patients were registered. Main outcome measure Toxicity of the intrathecal therapy was recorded and possible risk factors were assessed. Results A total of 269 administrations of triple intrathecal chemotherapy were registered in 41 patients (mean age = 6.6 ± 3.9 years). In 16.7% of the procedures, an adverse event was reported (total number of adverse events = 61). 47.5% were grade 1, 47.5% grade 2 and 4.9% grade 3. The administration of intrathecal chemotherapy inpatient and patient age ≥3 years were risk factors of toxicity in the multivariate analysis. Conclusions The administration of standardized triple intrathecal chemotherapy is related to a low frequency of toxicity and most of the adverse events registered were mild/moderate. The detection of adverse effects was significantly greater in children with age greater than or equal to three years and in hospitalized patients.

Triple intrathecal standardized preparations of methotrexate, cytarabine, and hydrocortisone sodium phosphate are physically and chemically stable at 25℃ for 48 h and at 2-8℃ for 5 days.