Which of the following examples does NOT belong to HOCM?

Iodixanol (Visipaque) is an iso-osmolar contrast agent, which distinguishes it from the other options, all of which are hyperosmolar contrast media (HOCM). Hyperosmolar contrast agents, like ioversol, iothalamate meglumine, and diatrizoate sodium, have elevated osmolarity compared to blood plasma, which can lead to a higher incidence of adverse reactions such as nephrotoxicity and discomfort during administration.

In contrast, iodixanol operates at an osmolarity that is approximately equal to that of blood plasma, allowing for a more favorable safety profile in certain patient populations. This iso-osmolar characteristic contributes to a reduced risk of side effects and makes iodixanol a preferable option for patients who may be at higher risk when using hyperosmolar agents. Thus, it does not belong to the category of hyperosmolar contrast media (HOCM).