5‐fluorouracil intravenous infusion for 48 hours, repeated every two weeks

High dose, continuous intravenous (I.V.) infusion of 5‐FU was evaluated in a Phase I Study. Doses of 30, 40, 50 or 60 mg/kg/day were administered for 48 hours, and subsequent courses were given at two week intervals. Sixty‐six courses of therapy were evaluated in twenty‐six patients, the majority of whom had carcinoma of the gastrointestinal tract (16) or breast (5). Only four patients failed to receive a second course of therapy. The median was 3 and the mean was 2.54 courses per patient. Serious leukopenia (WBC<2000) occurred in five patients, all of whom recovered. Other toxic reactions included nausea, vomiting, stomatitis, diarrhea, microscopic hematuria, phlebitis and thrombocytopenia. The toxicity of 5‐FU was dose related and 22 of 26 patients showed one or more toxic manifestations. Subjective improvement occurred in seven patients, and seven patients showed tumor progression during the study. This study suggests that 48 hour infusions of 30 mg/kg/day, repeated every two weeks, would be feasible.