Fate of Injected Radioiodinated 4-Iodoantipyrine in the Dog and Rat. ∗

Abstract

Summary and conclusions

These studies show that the dog, like the rat, rapidly converts RIAP to a more diffusible form and that the liver is the primary site of this conversion. Chromatographic analysis of serial plasma samples following RIAP injection in the rat indicated that as early as 15 minutes most of the plasma radioactivity was due to free I¹³¹ and not RIAP, thus invalidating the use of this compound in total body water studies. Finally, chromatographic analyses of dog and rat bile following RIAP administration showed that in addition to RIAP and free I¹³¹, the majority of radioactivity excreted was in the form of 3 as yet unknown compounds.