High-osmolar and low-osmolar contrast media. An update on frequency of adverse drug reactions.

During the past 3 years a great number of papers about adverse drug reactions to intravascular injection of high-osmolar and low-osmolar iodinated contrast media (CM) have been published. They include observational studies, randomized trials, meta-analyses and committee reports. Thorough analysis of this material substantiates an improvement in safety of at least 6-fold using nonionic low-osmolar CM compared with ionic high-osmolar CM. The point where only a small minority is continuing to argue effectively that low-osmolar CM are not better than conventional high-osmolar CM has now been reached. High-osmolar CM are used less and less for intravascular purposes, and, in fact, have been totally replaced by low-osmolar CM in 4 countries.