Schedule dependency of 5-fluorouracil

5i-Fluorouracil (5-FU) is cell-cycle specific for its cytotoxicity and has a pharmacokinetic profile characterized by a short, single-dose half-life o f 10 to 20 minutes in plasma. Efforts to maximize its clinical efficacy hav e been directed at overcoming this short half-life. Strategies have include d prolonging intracellular exposure by biochemical modulation or administra tion by infusional schedules, and more recently by chronic oral dosing. A n umber of clinical trials comparing routes of administration and biochemical modulation of 5-FU are presented in this article. Issues of dose intensity , differing toxicity profiles, and pharmacoeconomics are reviewed.