Concomitant administration of 4-hydroxypyrazolopyrimidine (allopurinol) and high-dose continuous infusion 5-fluorouracil.

We tried to study the protection of allopurinol (HPP) from the toxicity of 5-fluorouracil (5-FU). A total of 29 patients received 74 cycles of chemotherapy (16 colon adenocarcinomas, 7 head and neck, 3 breast cancers and 3 cancers of pancreas). HPP was given 900 mg/day p.