Clinical trial program for iopentol. A new nonionic ratio 3.0 contrast medium with emphasis on clinical phases I and II.

Iopentol is a new nonionic, water-soluble ratio 3.0 roentgen contrast medium (CM) for vascular use. The aim is to present the vascular clinical trial program for iopentol and to report the findings from the clinical phases I and II. The clinical program started with an intravenous (IV) safety and pharmacokinetic phase I trial (24 volunteers) and continued with six open, noncomparative phase II trials (61 patients) for studying cardiovascular and arterial tolerance (two trials in cardioangiography), venous tolerance (two trials in IV computed tomography [CT] enhancement), and cerebral and arterial tolerance (2 trials in cerebral arteriography). One volunteer in the phase I trial was excluded because of a vasovagal reaction following saline injection, and four patients were protocol deviators in cardioangiography. Mainly renal glomerular filtration of unmetabolized iopentol, close to 100% recovered after 24 hours in the urine, was found in the phase I study. No unexpected or severe contrast-induced reactions were encountered in phases I and II. Good diagnostic efficiency was obtained in phase II. As also expected, iopentol seemed to be well-tolerated. However, its relative efficiency and tolerance profile can only be documented from the ongoing comparative phase III trials.