Pemetrexed disodium heptahydrate is an organic sodium salt that is the heptahydrate form of pemetrexed disodium. Inhibits thymidylate synthase (TS), 421 dihydrofolate reductase (DHFR), and glycinamide ribonucleotide formyltransferase (GARFT). It has a role as an antimetabolite, an antineoplastic agent, an EC 1.5.1.3 (dihydrofolate reductase) inhibitor, an EC 2.1.1.45 (thymidylate synthase) inhibitor and an EC 2.1.2.2 (phosphoribosylglycinamide formyltransferase) inhibitor. It is a hydrate and an organic sodium salt. It contains a pemetrexed disodium.