Effects of a low-fat meal on the oral bioavailability of UFT and leucovorin in patients with colorectal cancer
UFT is composed of tegafur, a prodrug of 5-fluorouracil, and uracil, at a fixed ratio of 1: 4. UFT is widely used with leucovorin as adjuvant chemotherapy in patients with colon cancer. As reported, UFT/leucovorin should not be taken simultaneously with food because a high fat content will reduce the systemic exposure to the active cytotoxic moiety of UFT. In this single-dose, randomized, two-way crossover study, we investigated the effects of a low-fat Japanese meal on the pharmacokinetics and oral bioavailability of UFT (2 × 100-mg capsules; dose in terms of tegafur) and leucovorin (1 × 25-mg tablet). Patients (n = 12) were randomly assigned to receive both drugs after an overnight fast or 5 min after eating a standard Japanese breakfast (641 kcal), with a 3-day washout period between treatments. Pharmacokinetics (n = 12) were determined for tegafur, 5-fluorouracil, uracil, leucovorin, and 5-methyltetrahydrofolate (an active metabolite of leucovorin). For 5-fluorouracil pharmacokinetics, the maximum plasma concentration and the area under the curve were reduced by 73.7% and 47.4%, respectively, when UFT was taken postprandially, and the maximum plasma concentration and the area under the curve for uracil were reduced by 84.1% and 68.9%, respectively, compared with dosing on an empty stomach. These decreases in the systemic exposure to 5-fluorouracil were quite marked and may have an impact on its antitumor effect. A low-fat meal affects the pharmacokinetics of UFT similarly to a high-fat meal.