Aminopterin

Aminopterin is an amino derivative of folic acid, which was once used as an antineoplastic agent in the treatment of pediatric leukemia. In the 1950's its production was discontinued in favor of methotrexate, which is less potent but less toxic. Off label, aminopterin has also been used in the treatment of psoriasis. Clinicians need to be aware of the characteristic teratologic effects of aminopterin and methotrexate.

Prior to its withdrawal, aminopterin was initially used in the treatment of childhood leukemia; specifically to induce remissions. Later, aminopterin was used off-label in the United States to treat psoriasis, yielding dramatic lesion clearing. Aminopterin was later supplanted by methotrexate for treating cancer because of its better therapeutic index. Aminopterin (as well as methotrexate) has also been explored for use as an abortifacient. However, their association with severe congenital malformations and teratogenic effects have become known as fetal aminopterin syndrome.