Non‐immediate hypersensitivity reactions to iomeprol: Diagnostic value of skin tests and cross‐reactivity with other iodinated contrast media

Abstract

Background Iodinated contrast media produce non‐immediate hypersensitivity reactions (NIHR). The goal of this prospective study was to determine the utility of skin tests and the subsequent tolerance to negative skin‐tested iodinated contrasts in patients with NIHR caused by iomeprol. Methods Prick and intradermal tests with iomeprol, iopamidol, iopromide, and iobitridol were performed in all patients. IV challenge with the causative contrast (iomeprol in 90%) was made if skin tests were negative. In case of a positive skin test with the causal contrast, or a positive challenge test with it, IV challenge test with an alternative, negative skin‐tested contrast was performed in all patients. Results Skin tests were positive in 47.6% (20/42) of patients with NIHR induced by iomeprol. Of the 66 challenge tests performed with negative skin‐tested iodinated contrasts, tolerance was confirmed in 35 (53%): 32 iomeron, 2 iobitridol, 1 iopamidol. Cross‐reactivity between iomeprol and iopamidol was 22% (4/20 in patients with positive skin tests and 5/21 in patients with negative skin tests). Conclusions Sensitivity of the skin tests was less than 50% NIHRs due to iomeprol, while the negative predictive value of skin tests in patients who tolerated challenges with alternative contrasts (mainly iopamidol) was 53% (35 tolerated out of 66 performed). The cross‐reactivity between iomeprol and iopamidol is high.

Management of acute coronary syndromes requiring coronary angiography in patients with drug reaction with eosinophilia and systemic symptoms syndrome induced by iodinated contrast media: two case reports and narrative review

“…However, especially in cases of allergic reaction to ICM, it is not infrequent for patients to undergo other radiologic procedure requiring their administration. Furthermore, contrast media have demonstrated a significant cross-reactivity in eliciting allergic reactions, 6 especially for those with structural similarities. Cross-reactivity does not appear to be related neither to iodine and ionicity nor to excipients, rather to the presence of carbamoyl side chains in some ICMs; coherently, with these observations, a classification of ICMs in three classes (A, B, and C) based on the presence of the carbamoyl chain and the molecular structure of the ICM was created.…”