Stability of nonionic water-soluble contrast media: implications for their design.

The stability of the nonionic contrast media metrizamide, P-297, iopamidol, and nonionic phenyl ether DS-1-132 was studied by exposing their aqueous solutions to 120 C. Metrizamide showed decomposition of the sugar residue, while in P-297 the sugar substituent was cleaved off the triiodoaniline moiety. Iopamidol and DS-1-132 showed no decomposition. For stability, sugar moieties should be attached either by an ether linkage or as amides, as long as the acylamino group is not on a carbon adjacent to the anomeric carbon. Polyhydroxyalkylamines are less hydrophilic but more stable than sugars.