PHARMACODYNAMIC EFFECTS OF IOMEPROL FOR INJECTION IN EXPERIMENTAL-ANIMALS

Iomeprol for injection is a new nonionic triiodinated contrast medium for diagnostic radiology, which combines low osmolality with low visco sity. The effects of iomeprol for injection on the cardiovascular syst em, blood parameters, renal function and the central nervous system we re studied after intravascular administration to several animal specie s of doses at least as high as the highest presumed clinical doses. Th e following observations were made with respect to the central circula tory system: moderate and short-lasting increases of left ventricular end-diastolic pressure and cardiac output, no significant effects on h eart rate either in vitro or in vivo, some episodes of arrhythmia and ventricular fibrillations only at doses far higher than the highest pr esumed clinical ones, no significant increases in diastolic and systol ic coronary flow. The following observations were made with respect to peripheral circulation: no significant changes on blood pressure, mod erate and short-lasting increases in renal and pulmonary arterial flow , together with a decrease in peripheral vascular resistance, no cross ing of the blood-brain barrier in healthy animals. Cardiovascular and haemodynamic changes were all significantly milder than those induced by ionic contrast media (CM) and were similar to effects caused by som e other nonionic contrast media. When injected into the femoral artery of rats, iomeprol was shown to be less algogenic than iopamidol and i ohexol. In comparison with the same reference CM, iomeprol affected to a lesser extent the filterability of red blood cells in vitro and sho wed a less marked effect on their deformability. When administered int ravenously at very high dosages, iomeprol had no effect on the glomeru lar filtration rate, but increased both renal blood flow and diuresis. Proteinuria and enzymuria were also increased, albeit more transientl y. The neurotolerance of iomeprol for injection after intravenous admi nistration was higher than or at worst equal to that of iopamidol and iohexol. Iomeprol is therefore a promising new contrast agent particul arly suitable for intravascular use in humans.