Plasmatic diatrizoate-I¹³¹ disappearance and glomerular filtration in the dog

¹ Mayo Clinic and Mayo Foundation, Rochester, Minnesota

A study was made of the disappearance of sodium diatrizoate-I¹³¹ from the plasma of ten dogs after single intravenous injections. The plasma disappearance curves suggested a two-compartment system. The renal plasma clearance of diatrizoate-I¹³¹ calculated from these curves and the conventional renal plasma clearance of creatinine were not statistically different. Clearances calculated from the urinary excretion and midperiod plasma concentration of radioactivity in four experiments yielded values averaging 10% less than the creatinine clearance. Chromatographic studies of commercially available diatrizoate-I¹³¹ revealed the presence of about 5% free iodide and of about 5% of unidentified impurities. These impurities seem to account, partly at least, for the differences found between diatrizoate clearance and creatinine clearance. Biliary excretion and erythrocytic uptake of diatrizoate were minimal and did not appear to influence the analysis.