Preclinical safety assessment of contrast media: predictive value.

The purpose of preclinical tests is to identify the potential benefits and risks of new diagnostic or therapeutic products. Regarding iodinated contrast media (CM), LD50 tests were used extensively in the past. However, from both scientific and ethical perspectives, it is today highly relevant to question the use of LD50 tests. Due to species differences and the very high volume of CM needed to kill half of the animals, such tests are not sensitive enough to differentiate between modern nonionic CM. Further, they are not very predictive in terms of human tolerability. In other tests with more relevant end-points than death, overall tolerance to the new dimeric compound iodixanol (Visipaque), representing the latest step in the development of CM, has been shown to be higher than to the nonionic monomers. Clinical experience has shown that the physiological parameters often stay closer to baseline after Visipaque than after administration of conventional CM.