Activation of platelets by low-osmolar contrast media: differential effects of ionic and nonionic agents.

Abstract

To determine the effects of an ionic low-osmolar contrast medium (ioxaglate) and two nonionic low-osmolar contrast media (iohexol and iopamidol) on human platelet activation in vitro. Flow cytometry analysis subsequent to reaction with fluorescence-labeled monoclonal antibodies was used to detect antigens that appear on the platelet surface on activation. Ioxaglate did not activate platelets, but evidence of platelet activation by iohexol and iopamidol was found in blood from two and three healthy volunteers, respectively, of the six volunteers studied. In addition, ioxaglate inhibited the thrombin-induced in vitro activation of platelets, whereas iohexol and iopamidol did not. These findings support a tendency toward a higher frequency of thromboembolic complications with nonionic low-osmolar contrast media, although clinical trials will be needed to confirm this possible trend.