甲氨蝶呤-甲基-d3是氘化形式的甲氨蝶呤，一种抗肿瘤药和抗风湿药。研究表明，甲氨蝶呤-甲基-d3可以作为叶酸拮抗剂。甲氨蝶呤竞争性且不可逆地抑制四氢叶酸合成中必不可少的二氢叶酸还原酶（DHFR）。另外，四氢叶酸合成的减少引起嘌呤碱基合成的减少，这导致DNA，RNA，胸苷酸和蛋白质的抑制。替代研究表明，甲氨蝶呤-甲基-d3可通过抑制IL-1抑制T细胞活化和粘附分子表达。 Methotrexate-methyl-d3 is a deuterated form of methotrexate, an antineoplastic and antirheumatic agent. Studies indicate that methotrexate-methyl-d3 can act as a folic acid antagonist. Methotrexate competitively and irreversibly inhibits dihydrofolate reductase (DHFR) which is essential in tetrahydrofolate synthesis. In addition, the reduction in tetrahydrofolate synthesis causes a decrease in purine base synthesis which results in the inhibition of DNA, RNA, thymidylates, and proteins. Alternate studies suggest that methotrexate-methyl-d3 can suppress T cell activation and adhesion molecule expression through IL-1 suppression.