Pharmacokinetics, Metabolism, and Excretion of Iopamidol in Healthy Subjects

ABSTRACTThe pharmacokinetics and disposition of iopamidol, a new nonionic radiocontrast agent, were assessed in healthy subjects. Two formulations of iopamidol, with iodine concentrations of either 200 or 300 mg/ml, were given intravenously at various doses to 43 healthy adult males in three separate studies. Serial samples of plasma, urine, and feces were assayed for concentrations of iopamidol and possible metabolities. The plasma kinetics could be described by a standard two-compartment, open model. Iopamidol was cleared rapidly from the circulation, with a mean terminal half-life of about 2 hours. The volume of distribution approximated that of extracellular fluid. Negligible amounts of iopamidol were bound to plasma proteins. Iopamidol was excreted primarily by the kidneys, with urinary recovery of at least half the dose within 2 hours and 90% or more of the dose within 72 to 96 hours after injection. Fecal elimination averaged 1% or less of the dose. No metabolites of iopamidol were detected in the urine.