NCIt definition : The sodium salt of leucovorin, an active metabolite of folic acid, used as an antidote
to folic acid antagonists. Leucovorin does not require metabolism by dihydrofolate
reductase, the molecular target of folate antagonists and counteracts the toxic effects
of these drugs. This agent also potentiates the effects of fluorouracil and its derivatives
by stabilizing the binding of the drug's metabolite to its target enzyme, thus prolonging
drug activity. In comparison with the calcium salt, sodium salt does not form precipitate
when mixed other folate antagonists.;