Methotrexate

Methotrexate (MTX) is a clinically important antifolate drug, which competitively inhibits dihydrofolate reductase (DHFR), thereby impairing folate production. Folate is necessary for the de novo synthesis of thymidine, required for DNA synthesis. Folate is also required for purine base synthesis of DNA, RNA, thymidylates, and proteins. Thus, methotrexate impairs synthesis of thymidine and other metabolites crucial for cell proliferation.

Methotrexate (MTX), formerly known as amethopterin, is a chemotherapy agent and immune system suppressant. It is used to treat cancer, autoimmune diseases, ectopic pregnancy, and for medical abortions. Types of cancers it is used for include breast cancer, leukemia, lung cancer, lymphoma, and osteosarcoma. Types of autoimmune diseases it is used for include psoriasis, rheumatoid arthritis, and Crohn's disease. It can be given by mouth or by injection.