Efficacy of intravenous pretesting and antihistamine prophylaxis in radiocontrast media--sensitive patients

The involvement of osmolarity in the safety of contrast media

Background

New non-ionic contrast agents, classified into low osmolar agents and iso-osmolar agents, present different biochemical characteristics that may influence the allergic reactions they cause. The aim of our study was to evaluate how osmolarity may affect safety in the use of contrast agents.

Case presentation

Six patients with a positive history for reaction to contrast agent were included in this study. Only one patient prick and intradermal skin test was positive. However, in 5 cases, patients presented an immediate reaction after administration of contrast agent that was not IgE mediated.

Conclusions

In this study, we focused on iodixanol, an iso-osmolar contrast agent, finding good safety of this product in patients with previous hypersensitivity reactions to contrast agent.

Successful Graded Dose Challenge to Iodixanol Radiocontrast Media in a Patient With Delayed Anaphylaxis to Iohexol

We present a case of an 82-year-old male with known radiocontrast media (RCM) hypersensitivity who was admitted to our hospital with gangrene of his right toe. The plan for revascularization of his lower extremity required an angiogram. This presented a management challenge as the patient had experienced 2 episodes of delayed anaphylaxis to Omnipaque (iohexol) RCM, and based on a literature review, there was no known or established precedent on a safe procedure in these situations. The patient was premedicated and given a graded dose challenge of an alternative RCM (iodixanol) prior to the radiographic study. He was given 1% of the total expected dose 1 hour before to the procedure and an additional 10% for the 30 minutes prior. He was then given the final dose in the operating room. Following angiogram, the patient was monitored for 18 hours in the postanesthesia care unit, with no adverse reactions. He was placed on a prednisone taper for 1 week, with daily diphenhydramine. The patient remained asymptomatic throughout the hospital course. This novel approach to RCM hypersensitivity management lends itself to a hope that graded dose challenges may play a greater role in the management of these patients.

[Clinical practise guideline of the special interest group in allergy of the ÖGDV - Drug provocation testing in the diagnosis of cutaneous drug reactions]

Nowadays, clinical and evidence based guidelines are considered one of the major efforts to improve patient care in medical practices as well as hospital settings. In the literature, clinical guidelines have been defined as "systematically developed statements to assist practitioner and patient decisions about appropriate healthcare for specific clinical circumstances", which promote both clinically effective standards and cost-effective care. Despite controversial discussion about the clinical impact of guidelines, they may provide workable recommendations that may thus be important for improving the individual patient's care. Adverse drug reactions (drug allergies, drug hypersensitivities) often represent a major hazard for the affected patient, and a definite diagnosis is important for further drug therapies in most cases. In this context, any diagnostic procedure must be preceded by an individual risk-benefit assessment. Drug provocation testing is regarded as the gold standard, but this kind of testing should be performed in accordance with established criteria and, in the vast majority of cases, in a hospital setting. In this paper we present a clinical guideline for drug provocation testing in Austria.

Outcomes of premedication for non-ionic radio-contrast media hypersensitivity reactions in Korea

BACKGROUND

Radio-contrast media (CM)-related adverse reactions are important clinical problems that may cause fatal anaphylaxis. Accordingly, it has been common practice to premedicate patients who have had previous reactions to CM with corticosteroids, antihistamines, and H2 blockers to prevent hypersensitive reactions. However, the effectiveness of premedication has not been properly demonstrated, especially in cases related to non-ionic CM. In this study, we evaluated the effectiveness of premedication at preventing of non-ionic CM immediate-type hypersensitivity reactions.

METHODS

A total of 30 patients who had been pretreated with corticosteroid and H1 antihistamines and/or H2 blockers in a 3-year period were enrolled. The results of premedication were evaluated in terms of clinical characteristics and the features of breakthrough reactions.

RESULTS

Hypersensitivity reactions were not prevented in 5 of the 30 patients who had experienced prior CM reactions (overall recurrence rate after premedication 16.7%; 4/17 patients with mild previous reactions, and 1/13 patients with severe previous reactions). The recurrence rate after premedication was significantly higher in patients with mild previous reactions than in those with severe reactions (23.5% vs. 7.7%; p<0.001). The breakthrough reactions were similar to the prior reactions in terms of severity and clinical manifestations.

CONCLUSION

Premedication with corticosteroid and H1 antihistamines and/or H2 blockers effectively prevent non-ionic CM-related adverse events in most patients who have had severe previous reactions to CM. However, physicians should be aware of the possibility of premedication failing and of breakthrough reactions, even in cases in which the previous reactions were mild.

Provocation tests in drug hypersensitivity

Provocation tests are regarded as the "gold standard" to establish or exclude the presence of hypersensitivity to a certain drugs because they reproduce not only allergy symptoms but other adverse manifestations, irrespective of their pathomechanism. Provocation testing is potentially harmful and should be considered only after balancing the risk-benefit ratio in the individual patient. The reasons for false-positive and false-negative results are numerous, including loss of sensitization, cofactors not being included in the diagnostic procedure, and the potential induction of tolerance during provocation. When conducted by experienced clinicians in a carefully monitored setting, however, drug provocation testing is a safe method to confirm or exclude drug hypersensitivity.

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.

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

In the past few years, there have been an increasing number of publications on delayed intolerance reactions, including rashes, following the use of X-ray contrast media. We report a patient in whom infiltrated erythema of the face and generalized maculopapular rashes occurred on 2 occasions, within 1 day, following the use of the X-ray contrast medium Solutrast (iopamidol) for coronary angiography. The allergological investigations for clarification included prick tests and patch tests using a series of contrast media, as well as individual intravenous provocation tests. We found the cause to be a late-type allergy to the active substance iopamidol contained in the contrast medium Solutrast. We found a concomitant cross-reactivity to the contrast media iopromid and iomeprol. All 3 contrast media represent the monomeric, non-ionic type.

Contrast media are incomplete secretagogues acting on human basophils and mast cells isolated from heart and lung, but not skin tissue

To investigate the mechanisms of anaphylactoid reactions to radiocontrast media, in vitro mediator release induced by three iodinated contrast agents was examined using peripheral blood basophils and mast cells purified from human lung parenchyma, heart, and skin tissues. Three iodinated contrast agents, sodium and meglumine salts of ioxaglic acid, sodium and meglumine salts of ioxithalamic acid, and ioversol, were incubated with basophils purified from peripheral blood and human mast cells isolated and purified from different anatomical sites. Release of preformed (histamine and tryptase) and de novo synthesized mediators (prostaglandin D2 and leukotriene C4) into the supernatans was determined at various contrast medium concentrations after incubation for 60 min. Ioxaglate (0.2-0.3 M), ioxithalamate (0.3-0.5 M), and to a lesser extent ioversol (0.3-0.5 M) induced histamine release from basophils in a concentration-dependent manner. All three induced the release of preformed mediators (histamine and tryptase) from human lung, but not from skin mast cells. They also induced histamine and tryptase release from human heart mast cells. However, they did not induce the de novo synthesis of leukotriene C1 or prostaglandin D2 from human basophils or any type of mast cell examined. Cross-linking of IgE by anti-IgE induced the release of leukotriene C4 or prostaglandin D2 from human basophils or mast cells. Mannitol, an osmotic stimulus, induced the release of histamine from human basophils, but to a lesser extent from mast cells. These results show that different contrast media can differ in their ability to release mediators from enriched preparations of human basophils and mast cells. The three contrast agents examined act on basophils and mast cells as incomplete secretagogues, causing the release of preformed mediators, but not these novo synthesis of chemical mediators. It may be useful to measure plasma tryptase levels to detect adverse reactions caused by iodinated radiographic contrast materials.

Prevention of anaphylactoid reactions in high-risk patients receiving radiographic contrast media

OBJECTIVE

To review various pretreatment regimens for the prophylaxis of anaphylactoid reactions to radiographic contrast media (RCM) in high-risk patients. The proposed etiologies and risk factors for such reactions are also reviewed.

DATA SOURCES

A MEDLINE search of the English-language literature was used to identify pertinent human studies and reviews.

STUDY SELECTION

All studies comparing pretreatment regimens for anaphylactoid reactions to RCM were reviewed as well as studies comparing the incidence of anaphylactoid reactions between lower and higher osmolar RCM.

DATA SYNTHESIS

The two types of reactions to RCM are dose-independent, unpredictable anaphylactoid (pseudoallergic or idiosyncratic) reactions and the dose-dependent, predictable physicochemical (intrinsic, nonidiosyncratic) reactions. Prophylaxis of the former type is targeted at stemming the effects of certain chemical mediators, primarily histamine. The use of lower osmolar RCM is associated with a lower incidence of anaphylactoid reactions compared with higher osmolar RCM, but is significantly more expensive. Risk factors for such reactions are a history of previous anaphylactoid reaction to RCM, asthma, and reaction to skin allergens or penicillin. Discontinuation of any beta-blockers before the procedure is suggested. Pretesting patients with a small amount of RCM has little predictive value for an anaphylactoid reaction. Various pretreatment prophylactic regimens have been studied. Almost all included a corticosteroid to target the inflammatory response and a histamine1 (H1)-antagonist to blunt the effects of histamine. In some clinical trials, ephedrine was added for bronchodilation and cimetidine for its antagonism at the histamine2-receptor. The few controlled clinical trials that have been performed show the combination of prednisone and diphenhydramine to be most beneficial in preventing anaphylactoid reactions to RCM. The addition of ephedrine or cimetidine to a pretreatment regimen remains controversial.

CONCLUSIONS

More controlled clinical studies comparing various pretreatment regimens for high-risk patients need to be performed, especially in patients receiving lower osmolar RCM. Recommendations for high-risk patients who must receive RCM include use of a lower osmolar agent, pretreatment with a corticosteroid and an H1-antagonist, discontinuation of beta-blockers if the patient is taking any, and bedside availability of appropriate medications and equipment to treat anaphylaxis.

Anaphylactoid reaction to iopamiro (after pretreatment)

A patient is described with a past history of an anaphylactoid reaction to contrast media who reacted to nonionic contrast media after pretreatment with antihistamines and steroids. The available options to reduce the incidence of reactions include use of non-ionic contrast which has a reported lower frequency than ionic contrast or some form of pretreatment. Various forms of pretreatment have been described and in the majority steroids and antihistamines are used. We describe a patient who reacted to nonionic contrast after a pretreatment regime.

Adverse reactions of low osmolality contrast media during cardiac angiography: a prospective randomized multicenter study

A multicenter study was performed to determine the incidence of adverse reactions to two contrast media with similar low osmolality during cardiac angiography. The study was of a randomized double-blind design comparing ioxaglate (an ionic dimer) and iopamidol (a nonionic compound) and included 500 patients; 250 patients received ioxaglate and 250 iopamidol. There were 58 adverse reactions attributed to the contrast media in the ioxaglate group and 29 in the iopamidol group (p less than 0.001). Chest pain occurred in 11 patients in the ioxaglate group compared with 5 in the iopamidol group (p = 0.123). Nausea or vomiting was present in 20 and 2 patients, respectively (p less than 0.0003). Allergic adverse reactions, such as bronchospasm, urticaria and itching, occurred in 15 of the ioxaglate group and only 1 of the patients receiving iopamidol (p less than 0.0007). Fifty-two patients in the ioxaglate group had a known allergic history (not to contrast medium) or asthma, whereas 77 receiving iopamidol had a similar history. Seven of the 52 ioxaglate-treated patients developed an allergic adverse reaction compared with none of the 77 in the iopamidol group (p = 0.001). Of 41 patients receiving ioxaglate who were premedicated with diphenhydramine, 4 had an allergic adverse event. In the iopamidol group 45 patients received similar premedication and none had an allergic adverse reaction (p less than 0.03). Thus, this multicenter study shows that adverse reactions occur more often with ioxaglate than with iopamidol and that patients with an allergic history have a greater risk with ioxaglate therapy compared with iopamidol.

Contrast media for angiography: physicochemical properties, pharmacokinetics and biocompatibility

Contrast agents are used as diagnostic molecules for the visualization of the vascular system. Despite their rapid pharmacokinetic distribution, and their excretion within a few minutes, their injection is associated with clinical symptoms of relative bioincompatibility. Allergoid reactions and disturbances of the hemostatic system represent the main fields of biological investigations. Due to the extent of clinical and experimental works the ubiquitous interactions between these molecules and cellular and/or protein systems have emerged. The development of a new family of low osmolality ionic or non-ionic contrast molecules had decreased the incidence of minor reactions, but did not modify the frequency of severe accidents and even led to the emergence of new iatrogenic syndromes. Despite extensive laboratory investigations there are still no predictive criteria nor any specific therapeutic prevention of these allergoid reactions. The suggested future line of investigation concerns the physicochemical interaction of CM and targeted biological systems which may allow the analysis and predictivity of these interactions at the molecular level.

Pretreatment with corticosteroids to alleviate reactions to intravenous contrast material

The x-ray contrast mediums used over the past three decades have been salts of iodinated acids administered in highly hypertonic concentrations. We conducted a multiinstitutional randomized study of the protective effects of pretreatment with corticosteroids against reactions to intravenous contrast material. We gave 6763 patients two doses of oral corticosteroids (methylprednisolone, 32 mg) approximately 12 hours and 2 hours before challenge with contrast material, one dose of oral prednisolone approximately 2 hours before challenge, or placebo in the same dosages. The two-dose corticosteroid regimen, but not the one-dose regimen, significantly reduced the incidence of reactions of all types (P less than 0.05) except a category of reactions dominated by hives, for which the reduction approached significance (P = 0.055). In recent years, several relatively expensive monomeric nonionic iodinated compounds having approximately half the osmolality of the corresponding ionic compounds and a lower reaction rate have become available. With our two-dose corticosteroid regimen, the incidence of reactions necessitating therapy in patients receiving the ionic medium approximated that reported in an unblinded nonrandomized study of patients receiving a newer intravenous nonionic medium without corticosteroid pretreatment. We conclude that the much less expensive ionic medium, if administered with corticosteroid pretreatment, may serve as a reasonable alternative to intravenous nonionic medium, without loss of safety.

Anaphylactoid reaction to angiographic contrast media: recurrence despite pretreatment with corticosteroids

A case who developed severe and potentially fatal reaction to an angiographic contrast medium despite adequate pretreatment with steroids for 2 weeks is reported. This is the second such case reported in the English literature.

Desensitisation as a means of preventing untoward reactions to ionic contrast media

Patients with a previous history of anaphylactic reactions to ionic iodinated contrast media were desensitised before a second radiologic examination was performed. The tolerance to the contrast medium was raised by repeated intravenous injections in increasing doses and concentrations. No serious side effects were noted when the examinations with contrast medium was repeated within a few days after the desensitisation. The positive effect of the desensitisation may depend on a successive consumption of complement proteins, probably responsible for the allergic reactions. Therefore, the available amount of complement for some days may be too low for the occurrence of a complement reaction.

Prophylactic antihistamines in the management of radiographic contrast reactions

Two hundred and twenty consecutive patients, referred for intravenous pyelography, were assessed for adverse reactions. The effect of prophylactic antihistamines was evaluated. Patients were divided randomly into control, saline or chlorpheniramine treated groups. Changes in serum total haemolytic complement (CH50) and immune complexes (IC) at times 0, 1, 5, 10 and 20 min after injection of radiocontrast material were assayed. Forty-two of the 220 patients suffered reactions, classified clinically into allergic and non-allergic types. There was no difference in the incidence of allergic reactions between control and saline groups. However, significantly less (P less than 0.05) allergic reactions were noted in the antihistamine pre-treatment group. Depressed CH50 occurred in forty-three, of eighty-eight patients tested and persisted for at least 20 min in twenty-two. There was no correlation between CH50 depressions and clinical symptoms. The IC remained unchanged throughout. In conclusion, prophylactic antihistamines may diminish the incidence of allergic reactions. Complement activation occurs in a large number of patients, unrelated to symptomatology, and does not appear to be the only factor responsible for adverse reactions.

Adverse reactions to intravascular administration of contrast media

Adverse reactions to intravascular administration of contrast media, while low in incidence, merit serious consideration in view of increased utilization of these substances all over the world. Evidence for involvement of soluble mediators, antibody-antigen reactions, psychogenic factors, and the acute activation systems, is reviewed. As a group, the pre-contrast challenge plasmas of reactors are characterized by slightly diminished concentrations of Cl-esterase inhibitor and total hemolytic complement, and by an accelerated rate of conversion of prekallikrein to kallikrein on exposure to contact activators. The role of intravenous pretesting and pretreatment is considered. A rationale for pretreatment with adrenocorticosteroids is presented.