Definition of Methotrexate

Methotrexate: A drug that acts as an antimetabolite and specifically as a folic acid antagonist that inhibits the synthesis of DNA, RNA, and protein.

Methotrexate (MTX) is used to treat diseases associated with abnormally rapid cell growth such as certain tumors and psoriasis. Tumors treated with MTX include acute lymphocytic leukemia (ALL), acute myelocytic leukemia (AML), hydatidiform mole and choriocarcinoma, breast cancer, lung cancer, head and neck cancer, mycosis fungoides, and osteosarcoma.

Aside from psoriasis, methotrexate has also been found helpful in treating autoimmune diseases such as dermatomyositis and rheumatoid arthritis.

Methotrexate, especially in higher doses, can cause adverse reactions. The most frequent reactions include mouth sores, stomach upset, and low white blood counts. Methotrexate can be toxic to the bone marrow and liver.