Effect of a new nonionic contrast agent, ioxilan, on human erythrocytes and the hemostatic and serum complement pathways.

A new nonionic contrast medium (CM), ioxilan, was compared with iohexol and iopamidol. Following incubation of whole heparinized blood with CM, the morphology and osmotic fragility of erythrocytes were studied, the former by transmission electron microscopy. Effects on platelets and hemocoagulation were determined by standard hematologic procedures. Effects on serum complement were evaluated by measurement of total hemolytic complement (CH50), C3, C4 consumption and the presence in serums of C3c as determined by immunoelectrophoresis. Ioxilan affected the erythrocyte membrane less than iohexol and iopamidol: the latter two produced acanthocytes, whereas ioxilan had no effect on erythrocyte morphology; also, erythrocytes exposed to ioxilan (and iopamidol) were more resilient to hypotonic saline solutions than those exposed to iohexol. In all tests, all CM showed anticoagulant activity, albeit much less when compared with ionic CM. At equal iodine concentration, ioxilan reduced the platelet aggregation and whole blood clotting time more than did iohexol. None of the CM activated the serum complement system.