The chemical Methotrexate has a designated molecular formula of C20H22N8O5 and a molecular weight of 454.447 g/mol. Synonyms may include: R 9985, X 133, AI3-25299, Amethopterin L-, 4-Amino-10-methylfolic acid, 4-Aminomethylpteroylglutamic acid, 4-Amino-N(sup 10)-methylpteroylglutamic acid, Antifolan, N-Bismethylpteroylglutamic acid, CCRIS 1109, CL-14377, L-(+)-N-(p-(((2,4-Diamino-6-pteridinyl)methyl)methylamino)benzoyl)glutamic acid (ChemID). Methotrexate has been assigned a MeSH pharmacological action of: Antineoplastic, Enzyme Inhibitor, Folic Acid Antagonist, Immunosuppresant.