1. The active form of folic acid that acts as a formyl group carrier in transformylation reactions; the calcium salt, leucovorin calcium, has therapeutic use. 2. The term is occasionally applied to other folates. SYN: citrovorum factor, leucovorin.
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a derivative of folic acid involved in purine synthesis. Administered by mouth or by injection in the form of its calcium salts, it is used to reverse the biological effects of methotrexate and other dihydrofolate reductase inhibitor and so to prevent excessive toxicity. This action is termed folinic acid rescue. Folinic acid has a potentiating effect with fluorouracil, with which it is often used. Trade names: Isovorin, Lederfolin, Refolinon.
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fo·lin·ic ac·id (fo-linґik) the 5-formyl derivative of tetrahydrofolic acid; it can act as a coenzyme carrier in certain folate-mediated reactions but does not require dihydrofolate reductase activity and thus it is used, as the calcium salt leucovorin calcium, in treating some disorders of folic acid deficiency. Called also leucovorin and citrovorum factor.Medical dictionary. 2011.