[Non-ionic iodinated dimeric versus monomeric X-ray contrast media: effects on complement factors in vivo]

To survey contrast media (CM)-induced alterations of complement factors.

In 31 adult patients, who received either an iotrolan (n = 19) or iopromide (n = 12) i. v. injection for CT examination, complement factors C1 q, C3, C4, C5 a, and C1-esterase inhibitor in serum/plasma samples were analyzed. The samples were obtained prior to and 5 min., 30 min., 1 hr., 6 hrs. and 24 hrs. after CM injection.

5 patients (16.1 %) developed a CM reaction. 4 of these were patients who received iotrolan. Other than minimal data, we neither found a significant influence of the CM on complement activation nor a difference between the analyzed CM. In detail, 5 min. after CM administration, we found the tendency to be for the values to decrease and then to return to the basic value. The changes induced by iotrolan were more pronounced than those induced by iopromide; nevertheless the differences were not statistically significant. A more pronounced decrease of C3 and C4 after iotrolan injection indicates the activation of the classic way, while this could not been observed after iopromide injection. One patient who experienced an unwanted reaction towards iotrolan showed shifts of C1 q, C1 INH, C3 and C4.

The presented data shows different influences of CM injection on the analyzed complement factors after 5 min. that were commonly no longer present 30 min. after CM injection. The dimeric iotrolan induced a significantly increased frequency of unwanted CM reactions than the monomeric iopromide. The question of whether iotrolan is possibly able to activate the classic way of the complement cascade should be analyzed in the future in a greater patient group.