Vincristine in the etiology of toxicity of high-dose methotrexate therapy.

A 14-year-old received a six-hour infusion of methotrexate (71/2 g/M2) with vincristine (2 mg) and citrovorum rescue according to a standard protocol for adjunctive chemotherapy of osteogenic sarcoma. Signs of mild vincristine toxicity occurred from 2-5 days following the infusion; these including jaw pain, decreases in deep tendon reflexes, and a transient ileus. Clearance of serum methotrexate was delayed during the period of ileus and severe methotrexate toxicity was observed.