Iodohippurate Sodium 131I (OIH) Clearance in Mice Bioassay of Radiopharmaceuticals

Summary The renal plasma rates and modes of clearance of iodohippurate sodium 131I, 169Yb-DTPA, 113mIn-DTPA, and 99mTc-DTPA have been determined in mice and compared with those of inulin and OIH. The DTPA chelates or complexes of different radionuclides were found to be cleared by the mouse kidney by different pathways at surprisingly different rates. Clearance values were found to be closely reproducible, but should not be compared with values in man or other species. Iodohippurate sodium 131I can be used as a satisfactory clearance standard if it contains less than 1% free iodide in a formulation and concentration not toxic to renal function. The method reported has been shown to be a satisfactory bioassay for evaluating and comparing the clearance of radiopharmaceuticals of similar structure.