Clinical And Experimental Studies On The Ionic And Nonionic Contrast Media Interactions With Anticoagulant Drugs

Abstract

Interactions of ionic and non-ionic radiologic contrast media (CM) with anticoagulant drugs like heparin and Dex- tran-40 have been investigated. Renografin-60 (Squibb and Sons, Princeton, New Jersey), P-297, ioxigalic acid and iothalamic acid (Laboratoire Guerbet, Paris, France) were used. Human, monkey, dog and rabbit plasmas were incubated with CM, CM + heparin, CM + Dextran-40 and saline; prothrombin time (PT), partial thromboplastin time (PTT), and thrombin time (TT) were determined. In human plasma, Renografin-60 (final cone. 30 mg/ml) produced a strong anticoagulant effect and clotting times PT, PTT, and TT were prolonged by 1-1.5X their base value. When Renografin-60 was supplemented with 0.2u/ml heparin, the TT was greatly elevated, >100 secs, (control < 20 secs). No such prolongation of TT was noted when Dextran-40 was mixed into CM + plasma mixture. Iothalamic acid also showed potent anticoagulant action. P-297, which is a .non-ionic CM, showed the least anticoagulant action by itself, but did manifest some synergistic reaction with 0.2 - 0.4u/ml heparin (TT >100 secs, with 10 NIH u/ml thrombin). Similar results were obtained with monkey, dog and rabbit plasmas. In the in vivo experiments, dogs weighing 11-18kg were injected intravenously with 100-150 u sodium heparin/kg body weight, along with 50-100 ml Renografin-60. Blood samples were drawn at 1 hr., 3 hrs., 4 hrs., and 6 hrs., post injection and assayed for clotting times. 5 ml/kg CM injected with 25 u/kg heparin prolonged the activated partial thromboplastin time (APPT) and TT for upto 6 hours, while sodium heparin along produced anticoagulant effects for shorter duration (< 4 hours). Our studies indicate that ionic forms of CM produce relatively stronger antithrombotic response in animals as compared to non-ionic ones and utmost care should be exercised in their usage in patients on anticoagulant drugs.