Effect Of Ionic And Non-Ionic Contrast Media On Components Of Coagulation And Complement Pathways

The effects of a recently developed non-ionic contrast media (CM) P-297 and two ionic forms Ioxigalic acid and Iothalamic acid (Laboratoire Guerbet, Paris, France) were studied on coagulation and complement systems, and their interactions with anticoagulant drugs. In coagulation studies, a 1:10 mixture of P-297 (10%) in human plasma (both normal and abnormal) was prepared and prothrombin time (PT), partial thromboplastin time (PTT), and thrombin time (TT) were determined. Similar studies were performed with Ioxigalic acid (10%), and Iothalamic acid (10%). Separate pools of (10) individual plasmas representing disorders of intrinsic and extrinsic pathways of coagulation were similarly mixed with CM and the clotting times were determined. In all of these experiments, there was only a slight increase in TT whereas PTs and PTTs were not affected. Of the three CM tested, P-297 (10%) showed considerably less anticoagulant action than ioxigalic and iothalamic acids. All the CM exhibited a synergistic effect with 0.2u/ml heparin and greatly prolonged (>100 secs.) all coagulation tests. All of the three CM at (10 mg/ml) failed to produce any significant blockade of thrombin-induced aggregation of platelets, however at 40-80mg/ ml level did block thrombin-induced aggregation. In complement activation studies, serum C-3 levels in pre-and post-CM incubation samples were determined by a rocket technique. No consumption of the complement protein C-3 or split products of C-3 were seen in counter immunoelectrophoresis. These studies indicate that P-297 possesses mild anticoagulant and complement activating actions, and seems relatively safer than other ionic forms of CM. Furthermore, our studies suggest that non-ionic contrast agents produce minimal effects on coagulation and complement systems and can be used without much risk to patients with pre-existing coagulation and/or complement disorders.