Time course of biodistribution and changes in density following administration of iobitridol in rabbits. A comparative study vs iohexol.

Purpose: A new nonionic low-osmolality contrast medium, iobitridol (Xenetix 350) was compared with iohexol (Omnipaque) after i.v. injection in anesthetized rabbits to assess efficacy in CT examinations and biodistribution.

Material and methods: The densities in test tubes and the pharmacogenetics and biodistribution of iobitridol 350 and iohexol were compared in rabbits. CT of the brain, liver, the abdominal aorta and the kidneys was performed before and after injection of the contrast media.

Results: In aqueous medium, iobitridol absorbed roentgen rays in a manner exactly identical to that of iohexol. Within 15 min following injection of iohexol and iobitridol at a dose of 300 mg I/kg, both contrast agents resulted in aortic enhancement which decreased with time. An increased attenuation of the liver also occurred, decreasing with time. There was no significant enhancement in the brain but enhancement was found in the renal pelvocalyceal cavities 10 min postinjection. No significant difference was found between the 2 contrast agents under the study conditions.

Conclusion: As could be expected from its behavior as a tracer of extracellular fluid, iobitridol resulted in significant changes in the signal, corresponding to its vascular, hepatic and renal pharmacokinetics in rabbits.