Pemetrexed is a folate analog metabolic inhibitor. The drug substance, pemetrexed disodium (2.5 H2O), has the chemical name N-[[4-[2-(2-Amino-4-oxo-4,7-dihydro-1H-pyrrolo[2,3-d]pyrimidin-5-yl)ethyl]phenyl]carbonyl]-L-glutamic acid disodium, hemipentahydrate with a molecular formula of C20H19N5Na2O6 ∙2.5H2O and a molecular weight of 516.41. The structural formula is as follows:
Pemetrexed Injection, 100 mg/4 mL, 500 mg/20 mL, and 1 g/40 mL are supplied as a sterile, preservative-free, clear, colorless to pale yellow ready-to-dilute solution in a single-dose vial for intravenous infusion. Each milliliter (mL) contains 25 mg pemetrexed (equivalent to 27.57 mg pemetrexed disodium), 1.2 mg monothioglycerol, water for injection and may contain sodium hydroxide for pH adjustment.