Renal excretion mechanism of a nonionic contrast agent.

The renal excretion mechanism of a nonionic experimental contrast agent, C-29, was investigated in rabbits in comparison with the ionic contrast agent sodium diatrizoate under conditions of free urine flow and ureteral stasis. The two contrast agents were injected as a mixture of 125I-C-29 and 131I-sodium diatrizoate, in doses of 25 and 250 mg I/kg. The results indicate that, during the period relevant for urographic examinations, C-29 may have a renal clearance as low as 0.7 times that of sodium diatrizoate under conditions of both free urine flow and ureteral stasis. The biologic half-life of C-29 is 41-50 min.