IFEX (ifosfamide for injection, USP) single-dose vials for constitution and administration by intravenous infusion each contain 1 gram or 3 grams of sterile ifosfamide. Ifosfamide is a chemotherapeutic agent chemically related to the nitrogen mustards and a synthetic analog of cyclophosphamide. Ifosfamide is 3-(2-chloroethyl)-2-[(2-chloroethyl)amino]tetrahydro-2H1,3,2-oxazaphosphorine 2-oxide. The molecular formula is C7H15Cl2N2O2P and its molecular weight is 261.1. Its structural formula is: Ifosfamide is a white crystalline powder that is soluble in water.