Effects of viscosity on power and hand injection of iso-osmolar iodinated contrast media through thin catheters.

BACKGROUND: It can be challenging to achieve adequate vessel opacification during percutaneous coronary interventions when using thin catheters, hand injection, and iso-osmolar contrast media (CM) such as iodixanol (Visipaque™). PURPOSE: To explore these limitations and the possibility to overcome them with iosimenol, a novel CM. MATERIAL AND METHODS: Three X-ray contrast media with different concentrations were used in this study. A series of in vitro experiments established the relationship between injection pressure and flow rate in angiography catheters under various conditions. The experiments were conducted with power and hand injections and included a double-blind evaluation of user perception. RESULTS: By using hand injection, it was generally not possible to reach a maximum injection pressure exceeding 50 psi. The time within which volunteers were able to complete the injections, the area under the pressure-time curve (AUC), and assessment of ease of injection all were in favor of iosimenol compared with iodixanol, especially when using the 4F thin catheter. Within the pressure ranges tested, the power injections demonstrated that the amount of iodine delivered at a fixed pressure was strongly related to viscosity but unrelated to iodine concentration. CONCLUSION: There are substantial limitations to the amount of iodine that can be delivered through thin catheters by hand injection when iso-osmolar CM with high viscosity is used. The only viable solution, besides increasing the injection pressure, is to use a CM with lower viscosity, since the cost of increasing the concentration, in terms of increased viscosity and consequent reduction in flow, is too high. Iosimenol, an iso-osmolar CM with lower viscosity than iodixanol might therefore be a better alternative when thinner catheters are preferred, especially when the radial artery is used as the access site.

Iosimenol, a low-viscosity nonionic dimer: preclinical physicochemistry, pharmacology, and pharmacokinetics.

RATIONALE AND OBJECTIVES: Newer radiologic techniques require fast bolus injections and thus low-viscosity, high-concentration, well-tolerated contrast media (CM), especially in vulnerable patients. To this end, we designed and developed iosimenol, a novel isotonic nonionic dimer, and have conducted tests to enable its clinical evaluation. METHODS: Standard physicochemical methods were used. Effects on erythrocyte morphology and coagulation were investigated in human and rat blood. Neural tolerance was assessed by behavioral tests in rats after intracisternal injection. Immunosensitizing potential was evaluated by the skin sensitization test in guinea pigs and by the popliteal lymph node assay in rats. Pharmacokinetics and biotransformation were investigated in rats and dogs. RESULTS: Iosimenol is extremely hydrophilic, it is less viscous than any other isotonic CM, has little effect on erythrocytes and blood coagulation, and has good neural tolerance. No immunosensitizing effect was found in validated animal models. Pharmacokinetics are identical with other angio- and urographic CM. CONCLUSIONS: Iosimenol is the only CM which, although isotonic, affords, unlike current nonionic dimers, at the same iodine concentration the low viscosity of monomeric, nonionic agents, which are all hypertonic. Iosimenol's pharmacologic characteristics closely resemble those of iotrolan and iodixanol.