Chemotoxicity of contrast media and clinical adverse effects: a review

The clinical effects of contrast agents not only result from high osmolality, but also from their own specific pharmacology, which mediates chemotoxic effects. In this review, the chemotoxic effects of the new nonionic agent, iohexol, are compared with those of standard ionic and other low osmolality contrast agents, ionic and nonionic. Iohexol has the lowest chemotoxicity of any agent yet synthesized. Its low systemic toxicity is the combined result of low chemotoxicity and low osmolality. Mechanisms of severe adverse reactions are reviewed, including the views of Lasser and Lalli, and the view that emphasizes the importance of cardiotoxic and hemodynamic effects. It is concluded that whichever view is taken of the mechanisms of severe adverse reactions, the new nonionic agents are likely to be safer than the ionic agents now in use.