title: Oral DPD-inhibitory fluoropyrimidine drugs.
abstract: Over the past decade, increasing data have emphasized both the importance of dihydropyrimidine dehydrogenase (DPD), the initial, rate-limiting enzyme in the catabolism of fluorouracil (5-FU), and its role as a control step in 5-FU metabolism, regulating the availability of 5-FU for anabolism. It is now clear that DPD also accounts for much of the variability observed with therapeutic use of 5-FU, including variabilities in 5-FU levels over a 24-hour infusion, interindividual pharmacokinetics, bioavailability, toxicity, and drug response (resistance). This variability makes effective dosing of 5-FU and related drugs difficult. In order to lessen this variability, and potentially improve 5-FU pharmacology, the pharmaceutical industry has made an effort to develop DPD inhibitors to modulate 5-FU metabolism, which has resulted in the creation of a new subclass of orally administered fluoropyrimidines, known as DPD-inhibiting fluoropyrimidines (DIF). Four drugs--uracil and tegafur (UFT) or the combination of UFT and leucovorin, ethynyluracil (eniluracil), S-1, and BOF-A2--have recently undergone clinical evaluation in the United States. The biochemical basis for using these drugs is reviewed.
authors.affiliation: Department of Pharmacology and Toxicology, University of Alabama at Birmingham, USA.
authors.forename: R B
authors.initials: RB
authors.lastname: Diasio
mesh_terms: D000284:Administration, Oral; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage / Q000494:pharmacology*; D001682:Biological Availability; D042943:Dihydrouracil Dehydrogenase (NADP); D004338:Drug Combinations; D019008:Drug Resistance, Neoplasm; D005472:Fluorouracil / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics / Q000494:pharmacology*; D006801:Humans; D002955:Leucovorin / Q000008:administration & dosage / Q000494:pharmacology*; D010088:Oxidoreductases / Q000037:antagonists & inhibitors*; D010094:Oxonic Acid / Q000008:administration & dosage / Q000494:pharmacology*; D011725:Pyridines / Q000008:administration & dosage / Q000494:pharmacology*; D005641:Tegafur / Q000008:administration & dosage / Q000494:pharmacology*; D014498:Uracil / Q000008:administration & dosage
chemical_list: D000964:Antimetabolites, Antineoplastic; D004338:Drug Combinations; D011725:Pyridines; C079198:S 1 (combination); D005641:Tegafur; D014498:Uracil; D010094:Oxonic Acid; C053194:Emitefur; D010088:Oxidoreductases; D042943:Dihydrouracil Dehydrogenase (NADP); D002955:Leucovorin; D005472:Fluorouracil