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An in vitro and in vivo study of the effect of ionic and nonionic contrast media (CM) on coagulation and platelet function is reported. The methods employed were tests for extrinsic and intrinsic coagulation together with a fibrinolytic parameter and aggregation using ADP and collagen as inducers. The in vivo study utilized patients undergoing routine cerebral angiography. The in vitro results showed a modest influence of the nonionic CM in contrast to the ionic. The marked inhibitory effect of the latter was mainly caused by inherent toxicity, osmolality/ionic strength being of minor importance. The in vivo results showed a negligible influence of CM on systemic hemostatic parameters, but catheter-derived samples indicated desirability of premedication with ASA or heparin. The nonionic CM caused less discomfort than the ionic CM.

The effect on hemostatic parameters of two non-ionic contrast media, iopentol and iohexol in concentrations of 350 mg I/ml, were tested in vitro. The new medium iopentol had similar effects to those of iohexol, both with respect to the intrinsic coagulation system and platelet aggregation. As part of a human pharmacologic study the effects of iopentol on hemostatic parameters were tested in 8 volunteers in vivo. Iopentol induced a slightly decreased coagulability and aggregability in venous blood. It was concluded that the effects were of very little consequence for hemostasis as a whole.