Late-type allergy to the X-ray contrast medium Solutrast (iopamidol)

Drug provocation tests (DPTs) of contrast media: Useful or not useful? - A narrative review

Drug provocation tests (DPTs) are also used in some patients with a history of a contrast medium (CM)-hypersensitivity reaction. Since the use of contrast agents requires special knowledge that is present in radiology but not necessarily in allergology, this overview should close the knowledge gaps. The literature, and the package inserts of the industry dealing with DPTs in contrast hypersensitivity reactions was analyzed and the results presented. Historical analyses revealed that provocation tests were already done in the past, and called pre-testing. Due to disadvantages, this diagnostic tool was abandoned. A few years later, DPT was introduced as an innovative diagnostic procedure. The DPT has the 3 main disadvantages: a missing standardization, patients at risk (such as compromised renal function) are rarely taken into account, and a negative DPT does not exclude a subsequent CM reaction. DPTs (formerly called pre-testing) are a well-known method for diagnosing CM-related hypersensitivity reactions. Since the disadvantages of this diagnosis outweigh the advantages, we propose replacing DPT with routine contrast-enhanced imaging examination in radiology.

Iodine allergy: Common misperceptions

Disclaimer

In an effort to expedite the publication of articles related to the COVID-19 pandemic, AJHP is posting these manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

Purpose

The current evidence regarding iodine-containing compounds and iodine allergy cross-reactivity is reviewed.

Summary

Iodine is an essential human nutrient found in the thyroid gland. It is used in the synthesis of the thyroid hormones thyroxine and triiodothyroxine. Patients who report having adverse reactions to iodine-containing substances are often labelled as having an “iodine allergy,” which can result in delays in care or patients being denied essential ICM or other iodine-containing drugs. A literature review was conducted to evaluate the evidence regarding iodine allergy and iodine-containing drugs. Of 435 articles considered potentially appropriate for full review (plus 12 additional articles included on the basis of references from the eligible articles), 113 could not be obtained. After exclusion of 353 articles that did not meet all inclusion criteria, the remaining 81 articles were included in the review. The results of the literature review indicated that iodine has not been shown to be the allergen responsible for allergic reactions to iodinated contrast media, amiodarone, povidone-iodine, and other iodine-containing compounds.

Conclusion

There is a lack of evidence to support cross-reactivity between iodine-containing compounds in so called iodine-allergic individuals.

Controversies in Drug Allergy: Radiographic Contrast Media

The risk for developing immediate or delayed hypersensitivity reactions to radiocontrast media (RCM) interferes with the diagnosis and treatment of a number of patients requiring imaging diagnostic methods for many common diseases. A group of experts met in Orlando, Florida, in March 2018 to analyze the similarities and differences in the management of RCM reactions in different areas of the world. This paper presents a summary of the recommendations provided by this consensus group, highlighting controversial issues and unmet needs that require further research.

Diagnostic evaluation of patients with nonimmediate cutaneous hypersensitivity reactions to iodinated contrast media

BACKGROUND

Nonimmediate hypersensitivity reactions to iodinated contrast media (CM) are common. Allergological evaluation is necessary to confirm the diagnosis and to find a tolerated alternative. The aim of this study was to establish the role of skin testing and the drug provocation test (DPT) in the diagnosis of nonimmediate reactions to CM.

METHODS

Skin intradermal testing and patch testing with delayed readings were carried out with different CM (iobitridol, iomeprol, iodixanol, iohexol, ioversol, iopramide and ioxaglate). Single-blind placebo-controlled DPT was carried out in those cases with a negative skin test. In seven cases, a skin biopsy was obtained from positive skin tests and positive DPT.

RESULTS

Of the 161 subjects evaluated, 34 (21.1%) were skin-test positive, 21 (50%) to Iomeprol, 7 (16.7%) to Iodixanol, 5 (11.9%) to Iobitridol, 4 (9.5%) to Ioxaglate, 3 (7.1%) to Iohexol and 1 (2.4%) to Iopramide. DPT was positive in 44 cases (34.6%) that were skin-test negative, 38 (76%) to Iodixanol, 8 (16%) to Iomeprol and 4 (8%) to Iohexol. Of 78 cases (48.4%) with confirmed hypersensitivity, 34 (43.6%) were identified by skin testing and 44 (56.4%) by DPT. Skin biopsies showed a perivascular mononuclear cell infiltrate, mainly in the dermis, with higher levels of CD4 than CD8 T lymphocytes, with expression of activation markers and skin homing receptors.

CONCLUSION

Patients with nonimmediate reactions to CM were identified by skin testing in 43.6% and by DPT in 56.4%. The method to confirm the diagnosis differed depending on the CM involved.

Imaging efficiency of an X-ray contrast agent-incorporated polymeric microparticle

Biocompatible polymeric encapsulants have been widely used as a delivery vehicle for a variety of drugs and imaging agents. In this study, X-ray contrast agent (iopamidol) is encapsulated into a polymeric microparticle (polyvinyl alcohol) as a particulate flow tracer in synchrotron X-ray imaging system. The physical properties of the designed microparticles are investigated and correlated with enhancement in the imaging efficiency by experimental observation and theoretical interpretation. The X-ray absorption ability of the designed microparticle is assessed by Beer-Lambert-Bouguer law. Particle size, either in dried state or in solvent, primarily dominates the X-ray absorption ability under the given condition, thus affecting imaging efficiency of the designed X-ray contrast flow tracers.

The role of iodine in hypersensitivity reactions to radio contrast media

INTRODUCTION

Hypersensitivity reactions to iodinated radio contrast media (RCM) are either immediate-type (IT) or delayed reactions (DT). In IT, the pathomechanism is unclear. In DT, delayed positive patch (PT) and intradermal tests (IDT) and RCM-specific T cells suggest a T cell-mediated mechanism. In both, the role of iodine has not been clarified; however, patients are often labelled as 'iodine allergic'. Occasionally, positive skin tests to iodine-containing drugs are observed.

OBJECTIVE

We investigated the presence of hypersensitivity to iodine in patients with a history of hypersensitivity reactions to RCM.

METHODS

Nineteen patients with a history of IT (n=9) or DT (n=10) to RCM were investigated. Skin prick tests, IDT and PT with several RCM and iodine formulations were carried out. All underwent oral provocation with Lugol's solution (LS). Two patients each with iodine mumps, contact dermatitis to iodized antiseptics and chronic idiopathic urticaria served as control or proof of concept.

RESULTS

In the IT group, skin tests were positive in three out of nine patients to one RCM. One patient with negative skin tests reacted twice to oral iodine with urticaria. In the DT group, sensitization to one or several RCM was identified in 10 out of 10 patients. In seven out of 10 patients, additional sensitizations to the iodine formulations were found. Two patients developed a mild exanthema after oral provocation with LS.

CONCLUSION

We have previously demonstrated in patients with iodine mumps that an oral challenge with LS is a valid means to elicit hypersensitivity reactions to iodine. In 19 patients, we showed that iodine is rarely the eliciting agent in hypersensitivity reactions to RCM. Only one patient with a late urticaria to an RCM with a late urticaria to LS and two patients with DT and broad sensitization to all RCM tested reacted to LS with an exanthema. In most cases, more likely the RCM molecules and not iodine are the eliciting compounds.

[Immediate and delayed hypersensitivity reactions to iodinated radiographic contrast agents: an update]

Diagnostic and interventional radiology of patients is nowadays crucial with increasing requirement for iodinated contrast agents infusion. Besides adverse reactions after administration of the iodinated contrast agents due to their toxicity, immediate hypersensitivity reactions and reactions resembling delayed hypersensitivity appearing from 1 hour to several days later, have been reported. Patients at high risk to develop such adverse events have to be detected on the basis of their risk factors in order to prevent or limit serious outcomes. Previous reactions to contrast media, asthma, atopy and cardiovascular disorders are risk factors for anaphylactic or anaphylactoid reactions. Female gender, age and beta-blockers increase the severity. This article aims to summarize the risk of allergic reactions related to the use of iodinated contrast agents and to suggest a way for diagnosis, treatment and prevention according to each clinical situation.

Monitoring non-immediate allergic reactions to iodine contrast media

Non-immediate reactions to iodine contrast media (ICM) affect 2-5% of patients receiving these agents. We studied the immunological mechanisms involved in patients with a confirmed non-immediate reaction, maculopapular exanthema, after administration of ICM. The diagnosis was carried out by skin testing or drug provocation test. The immunological study was performed in sequential peripheral blood mononuclear cells taken from the onset of the reaction by flow cytometry and in skin biopsy by immunohistochemistry, with specific recognition by the lymphocyte transformation test (LTT) with different ICM. Flow cytometry showed an increase in the different activation markers [CD69, CD25 and human leucocyte antigen D-related (HLA-DR)] and the skin homing receptor [cutaneous lymphocyte-associated antigen (CLA)] in CD4 lymphocytes, whereas perforin was higher in the CD8 lymphocytes. The skin biopsy showed a perivascular mononuclear infiltrate composed of CD4 lymphocytes, expressing CD25, HLA-DR and CLA, with eosinophils. Intradermal skin tests and the LTT were positive to several ICM, including the culprit agent in four and three patients, respectively, with negative results in all 10 tolerant controls. We showed that a specific immunological mechanism was implicated in patients with non-immediate reactions to ICM. Moreover, the positive results in skin tests and lymphocyte proliferation tests indicated that an important cross-reactivity exists.

Late skin reaction to iodixanol (Visipaque�): clinical manifestations, patch test study, and histopathological evaluation

Late reactions to iodinated contrast media are frequent. Cutaneous manifestations are the commonest, in which maculopapular exanthema, a type of cutaneous presentation, is widespread. Controversy exists about the utility of the skin test in the management of these reactions. The aim of this study is to analyse the clinical characteristics, the histopathological findings, and the results of the patch test in patients who developed a late skin reaction (LSR) to the nonionic, dimeric, iodinated contrast media Visipaque. We retrospectively reviewed the patients with LSR to Visipaque, seen in the Dermatology Department between 1999 and 2005. A total of 12 patients participated in this study (7 men and 5 women), ages ranging from 39 to 76 years (mean 56). 11 of the patients had significant medical history. All the patients developed a maculopapular exanthema between 2 hr and 3 days after the radiological examination, involving the trunk and proximal limbs, although some of the patients showed involvement of distal areas. The skin biopsy, performed in 6 patients, showed nonspecific findings consistent with drug reaction. In 3 patients, patch tests to Visipaque and iodixanol were positive. The most frequent manifestation of LSR to iodixanol is a maculopapular exanthema, involving the trunk and the limbs, although distal involvement can be seen. Histopathological findings are nonspecific and cannot be distinguished from other drug reaction. Patch tests have a limited value, and in cases where they were negative, reintroduction of the drug triggered a new LSR.

A practical guide to diagnose lesser-known immediate and delayed contrast media-induced adverse cutaneous reactions

The terms "immediate" and "delayed" adverse reactions induced by contrast media (CM) refer to the reactions' onset but do not provide substantial information concerning the clinical manifestation, the potential risk factors, the treatment modalities, or prevention. Because a variety of different reactions caused by different pathophysiological mechanisms may arise immediately or be delayed after CM injection, and because these need different management, the aim of the present paper is to present the clinical features and to exactly characterize lesser-known cutaneous reactions. A thorough knowledge of the clinical features, their adequate treatment, and, possibly, the subsequent diagnostic procedure for preventing recurrence after reexposure to CM would improve patient management.

Allergy-like reactions to iodinated contrast agents. A critical analysis

Allergy-like reactions may occur following administration of iodinated contrast media (CM), mostly in at-risk patients (patients with history of previous reaction, history of allergy, co-treated with interleukin-2 or beta-blockers, etc.) but remain generally unpredictable. Severe and fatal reactions are very rare events. All categories of CM may induce such reactions, although first generation (high osmolar CM) have been found to induce a higher rate of adverse events than low osmolar CM. However, no differences were found between the two categories of CM with respect to mortality. Delayed reactions can also occur. There are no differences between the various categories of CM except for non-ionic dimers, which are more likely to induce such effect. Numerous clinical studies have evaluated the prophylactic value of drugs (mostly antihistamines and corticosteroids). Results are unclear and highly variable. Any prevention depends upon the mechanism involved. However, the mechanism of CM-induced allergy-like reaction remains disputed. Relatively recent data revived the hypothesis of a type-I hypersensitivity mechanism. Positive skin tests to CM have been reported. However, the affinity of IgE towards CM has been found to be very low in the only study which actually evaluated it. Other pathophysiological mechanisms (involving direct secretory effects on mast cells or basophils, or activation of the complement system associated or not with the plasma contact system) are also much debated. Anaphylaxis and anaphylactoid reactions are, in the end, clinically undistinguishable.

R�ntgenkontrastmittel�berempfindlichkeit

There has been a remarkable progress in our understanding of the pathophysiology of hypersensitivity to contrast media (CM). Immediate reactions develop within one hour after application of CM under the clinical picture of anaphylaxis. Pruritic exanthems appearing several days afterwards account for the majority of non-immediate reactions. Current evidence indicates an allergic basis of severe immediate as well as of non-immediate reactions involving CM-reactive IgE-antibodies and T-lymphocytes, respectively. Skin tests are helpful to establish the diagnosis of these reactions. The use of skin tests to predict tolerability of CM in patients with previous hypersensitivity reaction to CM is controversial. The value of cellular in-vitro tests is unknown. In patients with previous hypersensitivity to CM, premedication with antihistamins and/or corticosteroids is recommended, but current premedication protocols do not suppress all repeat reactions. European multicenter studies addressing sensitivity, specificity and predictive value of test procedures as well as prophylaxis and risk factors of CM hypersensitivity are currently ongoing.

Effective prophylactic protocol in delayed hypersensitivity to contrast media: report of a case involving lymphocyte transformation studies with different compounds

A patient with maculopapular reactions to iopamidol needed to undergo angiography for a cerebral arteriovenous malformation. In vivo and in vitro tests were performed with ionic and nonionic contrast media, including iopamidol and iobitridol. All results were positive, demonstrating delayed hypersensitivity. The patient received 6-alpha-methylprednisolone and cyclosporine 1 week before and 2 weeks after four angiograms were obtained with the use of iobitridol, which was well tolerated.

Late-onset allergy-like reactions to X-ray contrast media

PURPOSE OF REVIEW

The purpose of the present review is to describe recent insight into the pathomechanism of the late-onset allergy-like reactions which affect 2-3% of contrast medium-exposed patients, and to give advice regarding prophylactic measures to avoid recurrence of such reactions.

RECENT FINDINGS

It is well recognized that the majority of contrast media-induced late-onset reactions are cutaneous reactions of the maculopapular, urticarial and angioedema types, with occasional occurrence of more serious, bullous eruptions. Recent findings strongly indicate that these reactions are T cell-mediated. The current evidences for this concept are the described clinical symptoms; the high incidence of reactions in interleukin-2-treated patients; the positive results from skin, provocation and lymphocyte transformation testing of affected patients; and the histopathology of skin eruptions and positive skin test sites.

SUMMARY

On the basis of this new knowledge, several prophylactic measures are proposed to avoid repeat reactions in patients with previous late-onset contrast medium reactions. All persons receiving contrast media should be informed that transient skin reactions may develop up to 7 days after contrast medium exposure. Those who experience such reactions should be advised to see an allergist for diagnosis of the reaction. Skin testing with a panel of different contrast media appears to be useful for confirming the presence of an allergic reaction and for identifying alternative contrast media that can be safely used. For undiagnosed persons, a contrast medium that is structurally different from the product that precipitated the reaction should be chosen if re-exposure to contrast media is required. Pretreatment with corticosteroids may also be tried, although its protective effect has not been systematically studied.

[Anaphylactoid reactions and late skin reactions to iodinated contrast media: present state of the question--idea development]

PURPOSE

Adverse reactions to iodinated contrast media (ICM) share various mechanisms. Anaphylactoid reactions are among the most serious reactions when they are characterized by the elevation of seric tryptase. Pretreatment with corticosteroids and anti-H1 or the use of non-ionic contrast media do not prevent anaphylaxis. Late skin reactions could be mostly related to delayed hypersensitivity. Previous reactions to contrast media, cardiovascular disorders, beta-blockers, asthma, and atopy are risk factors. Female gender and age increase the severity.

CURRENT KNOWLEDGE AND KEY POINTS

Anaphylaxis can be demonstrated by intradermal tests and the identification of specific IgEs. Delayed hypersensitivity is shown by the results of epicutaneous tests and the immunohistology of the skin.

FUTURE PROSPECTS AND PROJECTS

Allergologic tests are advised in the case of previous reactions. In case of emergency, gadopentetate dimeglumine can be alternatively used. The other risk factors lead to the combination of pretreatment and use of non-ionic monomeric contrast media. Immediate hypersensitivity to iodinated media might increase in the near future with the use of divalent molecules.