As a folate reductase inhibitor, it mainly inhibits dihydrofolate reductase and prevents dihydrofolate from being reduced to physiologically active tetrahydrofolate, thereby hindering the transfer of one-carbon groups in the biosynthesis of purine nucleotides and pyrimidine nucleotides, resulting in the inhibition of DNA biosynthesis. In addition, it also has an inhibitory effect on thymic nucleotide synthetase, but the effect of inhibiting RNA and protein synthesis is weak. It mainly acts on the S phase of the cell cycle and is a cell cycle-specific drug. It also has a delaying effect on cells in the G1/S phase, but has a weaker effect on cells in the G1 phase.

This product has anti-tumor effects. Since it is a precursor of purine biosynthesis, it can interfere with purine biosynthesis. After entering the body, it demethylates to form monomethyl compounds in liver microsomes, which have direct cytotoxic effects. It mainly acts on the G2 phase. It inhibits the synthesis of purine, RNA and protein, and also affects the synthesis of DNA. Therefore, it is also considered to be an alkylating anti-tumor drug.

Folinic acid is a mixture of diastereoisomers of the 5-formyl derivative of tetrahydrofolate (THF), and its biologically active substance is the levorotatory isomer called levofolinic acid. L-folinic acid (L-5-formyltetrahydrofolate) is rapidly metabolized to 5,10-methyltetrahydrofolate and 5,10-folinoyltetrahydrofolate, and finally converted to L-5-methyltetrahydrofolate. L-5-methyltetrahydrofolate is metabolized to 5,10-methylenetetrahydrofolate through other pathways, which is irreversibly converted to 5-methyltetrahydrofolate through catalytic reduction by PDAH2 and NADPH coenzymes. The use of folinic acid can offset the therapeutic effects and toxicity of hydrochloric acid antagonists (such as methotrexate) that inhibit dihydrofolate reductase. Folinic acid can enhance the efficacy and toxicity of fluoropyrimidines (such as 5-fluorouracil) in tumor treatment. Folinic acid is easily converted into 5,10-methylenetetrahydrofolate in the body, which can stabilize the binding of deoxyfluorouracil nucleotide to thymidylate synthase, thereby enhancing the inhibitory effect on the enzyme.

Folinic acid is directly involved in biological reactions that use folic acid as a carrier for transferring "one-carbon groups" in the body without the need for reduction by dihydrofolate reductase. L-folinic acid (L-5-formyltetrahydrofolate) is rapidly metabolized to 5,10-methyltetrahydrofolate, 5,10-folinic tetrahydrofolate, and finally to L-5-methyltetrahydrofolate. L-5-methyltetrahydrofolate can be metabolized to 5,10-methylenetetrahydrofolate through other pathways, and 5,10-methylenetetrahydrofolate is irreversibly converted to 5-methyltetrahydrofolate through catalytic reduction by PDAH2 and NADPH coenzymes. Folinic acid can counteract the therapeutic effects and toxicity of hydrochloride antagonists (such as methotrexate) that inhibit dihydrofolate reductase. Folinic acid can enhance the efficacy and toxicity of fluoropyrimidines (such as 5-fluorouracil) in tumor treatment. Folinic acid is easily converted into 5,10-methylenetetrahydrofolate in the body, which can stabilize the binding of deoxyfluorouracil nucleotide to thymidylate synthase, thereby enhancing the inhibitory effect on the enzyme.

Folinic acid is a mixture of diastereoisomers of the 5-formyl derivative of tetrahydrofolate (THF), and its biologically active substance is the levorotatory isomer called levofolinic acid. L-folinic acid (L-5-formyltetrahydrofolate) is rapidly metabolized to L-5-methyltetrahydrofolate, and can be metabolized to 5,10-methylenetetrahydrofolate through other pathways, which can stabilize the binding of deoxyfluorouracil nucleotides to thymidylate synthase, thereby enhancing the inhibitory effect on the enzyme. Folinic acid can offset the therapeutic effect and toxicity of hydrochloric acid antagonists (such as methotrexate) that inhibit dihydrofolate reductase, and can enhance the efficacy and toxicity of fluoropyrimidines (such as 5-fluorouracil) in tumor treatment.