Methotrexate in Pediatric Clinical Practice: Therapeutic Monitoring and Toxicological Aspects

Chemotherapy plays a pivotal role in treating childhood cancer, involving various molecules. Methotrexate, widely used in pediatric oncology at doses exceeding 1 g/m², exhibits high inter-individual pharmacokinetic variability and significant toxicity. Regular monitoring of methotrexatemia levels may prove beneficial. Our study aims to demonstrate the value of therapeutic methotrexate monitoring for assessing toxicity and optimizing folic acid dosing based on methotrexatemia rates. We conducted this study on 12 children with acute lymphocytic leukemia, osteosarcoma, and nonHodgkin’s lymphoma. Methotrexate dosing employed the EMIT immunoenzymatic method. Among 48 dosages, 25% exceeded the toxicity threshold, with methotrexate directly implicated in effects for only one patient. Comparing recommended folic acid dosages to those prescribed by pediatricians revealed a 20% excess in folic acid use. Biochemical assessment-based methotrexate monitoring is a valuable tool for safe chemotherapy administration, facilitating toxic effect monitoring and proper folic acid supplementation.