A toxic antimetabolite,C20H22N8O5,that acts as a folic acid antagonist to interfere with cellular reproduction and is used in the treatment of psoriasis and certain cancers.

• 甲氨蝶呤一种有毒的抗代谢物，C20H22N8O5，作为叶酸拮抗药抵制细胞繁殖，用于治疗牛皮癣和一些癌症。