NCIt definition : The potassium salt of oxonate, an enzyme inhibitor that modulates 5- fluorouracil
(5-FU) toxicity. Potassium oxonate inhibits orotate phosphoribosyltransferase, which
catalyzes the conversion of 5-FU to its active or phosphorylated form, FUMP. Upon
oral administration, Oxonate is selectively distributed to the intracellular sites
of tissues lining the small intestines, producing localized inhibitory effects within
the gastrointestinal tract. As a result, 5-FU associated gastrointestinal toxic effects
are reduced and the incidence of diarrhea or mucositis is decreased in 5-FU related
therapy.;