methotrexate

small molecule

12.1 Mechanism of Action Methotrexate inhibits dihydrofolic acid reductase. Dihydrofolates must be reduced to tetrahydrofolates by this enzyme before they can be utilized as carriers of one-carbon groups in the synthesis of purine nucleotides and thymidylate. Therefore, methotrexate interferes with DNA synthesis, repair, and cellular replication. Actively proliferating tissues such as malignant cells, bone marrow, fetal cells, buccal and intestinal mucosa, and cells of the urinary bladder are in general more sensitive to this effect of methotrexate. The mechanism of action in rheumatoid arthritis and in psoriasis is unknown.

Thymidylate synthase, Bifunctional purine biosynthesis protein ATIC, Dihydrofolate reductase, Reduced folate transporter, Proton-coupled folate transporter

—

psoriasis — FDA

psoriasis, atopic dermatitis, alopecia areata, vitiligo

2026-04-19