[Late reactions to a radiologic contrast media (Iopamidol-Bracco). Prospective study]

This prospective, non-randomized study was aimed at evaluating the incidence of Delayed Adverse Drug Reactions (DADRs) to iodinated contrast agents and to evaluate possible risk factors to the development of these reactions. DADRs are those reactions occurring one to 48 hours after contrast medium administration. Their symptoms and frequency are not well defined, but the majority of DADRs are mild in intensity and resolve spontaneously without sequelae. In the literature, DADRs are reported to occur in 1 to 15% of patients undergoing contrast-enhanced examinations.

This prospective, non-randomized trial was carried out on 403 patients undergoing either dynamic CT or urography with iopamidol-300 (Iopamiro-300, Bracco SpA). Before the examination, data were collected regarding patients' anagraphical details, presence of risk factors, allergy, previous exposure and previous adverse reactions to iodinated contrast agent. After the examination, any adverse events occurring between 30 minutes and 48 hours post-dose were recorded, specifying time of onset and duration of symptoms. Studied variables were type of DADRs and risk factors to their development (sex, age, underlying disease, allergy, previous exposure to contrast agent, type of diagnostic examination). Two hundred and sixty-two patients were male (65%), and 141 were female (35%). Mean age was 61 years (+/- 11.8); 192 patients (48%) had underlying disease, and 115 (28%) were allergic. About half of the patients had previously undergone another contrast-enhanced examination. Two hundred and seventy-one patients underwent dynamic CT and 132 urography.

A total of 50 patients (12.4%) reported DADRs. Factors associated with a significantly higher incidence of DADRs were found to be allergy (p = 0.001), previous exposure to contrast agent (p = 0.001), female sex (p = 0.001), underlying disease (p = 0.030). The most frequently reported DADRs were nausea and vomiting, drowsiness, rash, itching and headache. All reported reactions were mild and resolved spontaneously without sequelae.

In our experience, though limited and not on large numbers, DADRs to nonionic low osmolality contrast agents such as iopamidol have been few, mild, and not clinically significant. Although there are no absolute contraindications to the use of iodinated contrast agent, the risk/benefit ratio should always be evaluated, especially in patients with allergy, in those with severe renal, hepatic or cardiac insufficiency, and in diabetics.