[Plasma kinetic study following oral administration of leucovorin tablets in patients with gastric cancer--influence of subtotal gastrectomy].

Patients with advanced gastric cancer were treated with methotrexate-5-fluorouracil sequential therapy. In order to rescue of methotrexate toxicity on the normal proliferating tissue, leucovorin was administered orally to outpatients. As the comparative study, we examined plasma kinetics following oral administration of leucovorin (15 mg) in 6 patients with gastric cancer (received subtotal gastrectomy) and 5 normal subjects. In the patients, peak plasma concentrations of d-1-formyltetrahydrofolate and its main metabolite 5-methyltetrahydrofolate were found after 2 hrs. (7.35 X 10(-7) M, 3.09 X 10(-7) M), and in normal controls also both after 2 hrs. (1.01 X 10(-6) M, 4.89 X 10(-7) M). The active folate metabolite persisted for more than 6 hrs. at over 1 X 10(-7) M that could rescue normal tissue from methotrexate toxicity after leucovorin oral administration in the patients received subtotal gastrectomy.