Injectable lower osmolar, nonionic, contrast media agent which is intended for intravascular administration. OPTIRAY 320 is a prescription drug that is intended to be therapeutically and biologically inert when injected into the body for use in organ or tissue enhancement in certain computed tomography, X-Ray and fluoroscopy imaging procedures. Each milliliter of OPTIRAY 320 contains 678 mg of ioversol, 3.6 mg of tromethamine as a buffer and 0.2 mg of edetate calcium disodium as a stabilizer.