Evaluation of serious adverse events in patients treated with protocols including methotrexate infusions.

During the period 1979 to 1992 we treated 141 children for various malignant diseases with protocols including methotrexate (MTX) infusions in doses ranging from 0.5 to 33.6 g/m2. During a total of 922 courses, there were no fatal complications associated with MTX treatment. Serum MTX concentration and pharmacokinetic data were monitored continuously during the infusions. In this study, we evaluated the occurrence of serious untoward reactions to MTX infusions. Impaired renal function with delayed drug elimination was seen in seven patients, all boys, especially after short infusion times. All recovered completely without any serious clinical symptoms. In three leukemia patients who later died from resistant disease, we observed late neurological disturbances and computer tomography (CT) brain scan abnormalities. Pharmacokinetic data from the patients with complications are described and confirm that serial MTX concentration monitoring is the most important early indicator of renal toxicity.