Allopurinol and Bolus Fluorouracil

To the Editor: Studies using continuous infusions of fluorouracil have shown that concurrent administration of allopurinol reduces fluorouracil's hematologic and gastrointestinal toxicity.^1,2 The dosage of fluorouracil can be markedly increased if allopurinol is given with it, resulting in a fourfold increase in the serum concentration of fluorouracil.² We designed a study, to test whether allopurinol would permit a clinically important escalation in a bolus dose of fluorouracil on a schedule suitable for outpatients. Allopurinol, 300 mg given orally three times a day, was begun one week before treatment and continued through the course of fluorouracil and for one week after.