Vincristine effect on methotrexate cerebrospinal fluid concentration.

A 67-year-old man with malignant lymphoma, nodular, poorly differentiated lymphocytic type, developed meningeal lymphomatosis. Repeated high-dose methotrexate-citrovorum factor treatment (1 g/m2 in 24 hours) rendered the patient free of disease. The administration of vincristine at 23 hours consistently increased the concentration of methotrexate in the cerebrospinal fluid 2.5-fold above baseline values.