Pharmacokinetic analysis of [6S]-5-formyltetrahydrofolate (l-CF), [6R]-5-formyltetrahydrofolate (d-CF) and 5-methyltetrahydrofolate (5-CH3-THF) in patients receiving constant i.v. infusion of high-dose [6RS]-5-formyltetrahydrofolate (leucovorin). Adv. Exp. Med. Biol. 244, 53-58....