Methotrexate (English: methotrexate, also known as methotrexate, methotrexate, methotrexate), Taiwan's trade name - miesha Chuai Ding. This drug is a folic acid antagonist, which is different from folic acid only in that the hydrogen on NH on N10 is changed to methyl (CH3), and the C4 keto group on the ring is changed to amino (NH2), so it can compete with folic acid for the same enzyme. It is an antimetabolic therapy drug, which can prevent (uracil) from transferring a methyl to (thymine) through folic acid, that is, an antineoplastic drug, or a drug to prevent the graft from reacting (rejecting) to the host. So it can suppress bone marrow activity and cause hepatitis. This drug was used in 1950s when methotrexate began to replace the more toxic antifolate drug aminopterin. The drug was first synthesized by Indian biochemist yellagragada Subbarao, who spent most of his career in the United States and was clinically developed by American pediatrician Sidney Farber. This is the drug on the World Health Organization's list of essential medicines, the most important of which is necessary in the basic health care system. It is one of the most important anti rheumatoid arthritis (RA) drugs, also known as disease modifying antirheumatic drugs (DMARDs). This is because it can reduce the inflammatory activity of some white blood cells (antibodies) and further slow down the bone damage. This drug can only be used by doctors with knowledge and experience of anti metabolic therapy. High dose therapy for malignant diseases has been reported.