[en] This study compared the disposition of the radiopharmaceutical [¹²³I]iodopentamidine with that of pentamidine after intravenous infusion by measuring plasma concentrations of each using scintilation counting and high-performance liquid chromatography (HPLC), respectively. There was rapid hepatic uptake and biliary excretion of the ¹²³I label. Distribution kinetics of the ¹²³I label were similar to those of pentamidine, but its elimination half-life (41 ± 27 h) was longer than that of pentamidine measured by HPLC (11 ± 8 h). [¹²³I]iodopentamidine distribution reflects that of pentamidine, but elimination of the radiopharmaceutical appears slower