Methotrexate

Methotrexate (formerly Amethopterin) is an antimetabolite drug used in treatment of cancer and autoimmune disease. It acts by inhibiting the metabolism of folic acid.

Uses

Methotrexate was originally used to treat many kinds of cancers as a type of chemotherapy. It is still the mainstay for treatment of acute lymphoblastic leukemia.

More recently it has come into use as a treatment for some autoimmune diseases, including psoriasis and arthritis. In the case of rheumatoid arthritis, parallel use with infliximab or etanercept has been shown to markedly improve symptoms.

It can be taken orally or by injection. Although daily preparations are occasionally used, many patients take weekly doses, which decreases the risk of certain side-effects.

Side effects

Possible side effects can include anemia, neutropenia, increased risk of bruising, and nausea. A small percentage of patients develop hepatitis, while there is an increased risk of pulmonary fibrosis.

Chemistry

Methotrexate's empirical formula is C₂₀H₂₂N₈O₅. Its structural name is N-[4-[[(2,4-diamino-6-pteridinyl)methyl]methylamino]benzoyl]-L-glutamic acid.

Mode of action

Methotrexate inhibits dihydrofolate reductase, an enzyme that is part of the folic acid metabolism. As folic acid is important in DNA synthesis, rapidly dividing cells develop a relative shortage of folic acid and die.

External links

Chembank entry on methotrexate