Folinic acid

A medication used to decrease the toxic effects of methotrexate and treat folate deficiency

Chemical structure of folinic acid

Folinic acid, also known as leucovorin, is a medication used to reduce the toxic effects of methotrexate and to treat folate deficiency. It is a form of folate that is used in various clinical settings, particularly in oncology and hematology.

Medical uses

Folinic acid is primarily used to diminish the side effects of high-dose methotrexate therapy in cancer treatment. Methotrexate is a chemotherapy agent that inhibits the enzyme dihydrofolate reductase, leading to a decrease in the production of tetrahydrofolate, a form of folate necessary for DNA synthesis and repair. Folinic acid provides a source of folate that bypasses the blocked enzyme, thus protecting normal cells from the toxic effects of methotrexate.

In addition to its role in cancer therapy, folinic acid is used to treat megaloblastic anemia due to folate deficiency, which can occur in conditions such as malabsorption syndromes or alcoholism. It is also used in combination with 5-fluorouracil in the treatment of colorectal cancer, where it enhances the effectiveness of the chemotherapy.

Mechanism of action

Folinic acid is a 5-formyl derivative of tetrahydrofolic acid and is readily converted to other reduced folic acid derivatives, such as 5,10-methylenetetrahydrofolate, which are active in the body. Unlike folic acid, folinic acid does not require reduction by dihydrofolate reductase to be active, making it effective even in the presence of methotrexate.

Pharmacokinetics

Folinic acid is well absorbed from the gastrointestinal tract and is metabolized in the liver to active forms of folate. It is distributed throughout the body, including the central nervous system, and is excreted primarily in the urine.

Side effects

Folinic acid is generally well tolerated, with few side effects. However, it can cause allergic reactions in some individuals. Rarely, it may cause gastrointestinal disturbances such as nausea and vomiting.

Stereochemistry

Chemical structure of levofolinic acid

Folinic acid exists as a mixture of two stereoisomers, the active form being levofolinic acid (also known as L-folinic acid or (6S)-folinic acid). The levo isomer is the biologically active form and is responsible for the therapeutic effects of the drug.

Related pages

• Folate
• Methotrexate
• 5-Fluorouracil
• Megaloblastic anemia

Ball-and-stick model of leucovorin

See also

• Vitamin B complex
• Chemotherapy
• Antifolate