Summary of U.S. and European intravascular experience with iohexol based on the clinical trial program.

The nonionic contrast medium, iohexol, was released by Nyegaard, Oslo, in 1980 for clinical testing. Results of a three-phase clinical trial program carried out in Europe and the U.S. through December 1983 are summarized. Evaluation of phase I studies of human tolerance and excretion--and phase II studies of effects on pharmacologic and physiologic parameters--indicated that iohexol was well tolerated and effective. Phase III consisted mainly of controlled parallel and crossover studies comparing iohexol with conventional ionic media and with other nonionic agents in a variety of radiographic studies. Image quality was as good or better with iohexol than with ionic media. Iohexol was tolerated significantly better than ionic agents. Patients consistently reported fewer and less intense pain and heat sensations. Iohexol had less effect on blood pressure, blood flow, heart rate, and electrophysiologic parameters, and caused fewer adverse reactions than ionic media for all types of reactions observed.