Interactions in iodinated contrast media solutions Part 1. A thermodynamic study

Contrast media are synthetic molecules often characterized by the presence of heavy atoms, such as iodine, widely used in diagnostic studies. In the framework of a study on the physico-chemical of non-ionic contrast media (NICM), this study reports the calorimetric data for a characterization of the thermodynamic behavior of the aqueous solutions of three NICMs, namely, iopamidol, iomeprol, and iopromide, characterized by the presence of three iodine atoms in the benzene ring. Hydrophilicity is provided by three side arms with polar groups. Here, the results of a calorimetric investigation on the heat of dilution of iopamidol, iomeprol, and iopromide and on iomeprol–iopamidol mixture are illustrated. Despite the very similar chemical structures, the dilution process of iopamidol and iopromide was found exothermic, while an endothermic dilution is shown by iomeprol. The results are discussed in terms of the few other literature data and on the basis of structural and conformational properties.