folinic

Folinic acid, also known as folinic or leucovorin, is a water-soluble reduced form of folic acid. Chemically, it is 5-formyltetrahydrofolate, the active form that participates in one-carbon transfer reactions essential for thymidylate and purine synthesis. Unlike folic acid, folinic acid does not require conversion by dihydrofolate reductase to become biologically active, allowing it to bypass blockade of the folate pathway.

Medical use and mechanism

Folinic acid is used to treat folate deficiency and to “rescue” normal cells during high-dose methotrexate therapy, reducing bone marrow suppression and mucositis. It may also be used to mitigate toxicities of other antifolate chemotherapy regimens in certain contexts. The rescue approach involves administering folinic acid after methotrexate to replenish cellular folate stores in healthy tissues while preserving methotrexate’s anti-tumor effects in cancer cells.

Administration and forms

Folinic acid is available in injectable forms and oral tablets. It is marketed as leucovorin calcium (folinic acid calcium salt) and as other folinic acid formulations. In clinical practice, dosing and route depend on the indication, with methotrexate rescue schedules tailored to the patient’s drug levels, kidney function, and clinical status.

Safety and considerations

Folinic acid is generally well tolerated, but it can mask vitamin B12 deficiency and should be used with caution in patients with undiagnosed anemia or known B12 deficiency. Potential adverse effects are uncommon but can include, depending on the individual, gastrointestinal symptoms or allergic reactions. Folinic acid should be used under medical supervision, particularly in the setting of chemotherapy.