Autoreactivity is highly prevalent in patients with multiple intolerances to NSAIDs

Multiple drug intolerance in antihypertensive patients: what is known and what is missing

Drug allergy and intolerance are increasingly recognized as significant public health concerns, leading to adverse reactions in patients undergoing pharmacological treatments. Multiple drug intolerance syndrome (MDIS), characterized by adverse reactions to at least three different drug classes without a clear immunological mechanism, poses a substantial challenge, particularly in hypertensive patients. Despite its link to suboptimal adherence and uncontrolled blood pressure, MDIS in the context of hypertension remains insufficiently explored. This review synthesizes existing literature on MDIS, emphasizing clinical characteristics, pathogenesis, and psychiatric comorbidity. Furthermore, it delves into MDIS in the context of hypertension, highlighting the importance of a multidisciplinary approach in diagnosis and management, including innovative therapeutic strategies such as novel therapeutic algorithms or renal denervation. The review concludes by emphasizing the necessity for further research and clinical trials to enhance our understanding and address MDIS, especially in hypertensive patients.

Rationale for the autologous serum skin test in acute versus chronic urticaria

Introduction

Autologous serum skin test (ASST) is a rapid, in-vivo clinical test to detect functional autoantibodies in patients with chronic spontaneous urticaria (CSU), but the rationale for its use in acute urticaria (AU) is unknown.

Aim

To evaluate the efficacy of ASST among patients with AU or CSU.

Material and methods

Treatment-naïve adult (age ≥ 18 years) patients with a diagnosis of AU (< 6 weeks’ duration) and CSU were enrolled prospectively in a cross-sectional study. Healthy age- and sex-matched subjects served as controls. Besides a detailed history and physical examination, ASST, total immunoglobulin E (IgE), freeT3 (fT3), freeT4 (fT4), anti-thyroglobulin, and anti-TPO levels were assessed in all subjects.

Results

Of 101 subjects, mean age was 34.35 ±12.68 years and the study comprised 58.4% of females with no difference between AU (n = 27), CSU (n = 46), and control groups (n = 28). The ratio of positivity in ASST was similar between AU (25.9%) and CSU groups (21.7%), but higher than in controls (10.7%, p = 0.33 for all). The ratio of patients with high total IgE levels (> 100 IU/ml) in AU (85.2%) and CSU (65.2%) groups was similar (p = 0.06), but significantly higher than in the control group (10.7%) (p< 0.001 and p< 0.001). The CSU group had significantly higher abnormal thyroid test results (45.7%) than AU (14.8%) and control groups (3.6%) (p = 0.01 and p< 0.001), whereas patients with clinically diagnosed thyroiditis were only in the CSU group (6.5%). In logistic regression analysis, there was no relation found among the possible risk factors for ASST, even if analysed separately as AU, CSU and control groups.

Conclusions

Even though thyroid function test levels were found to be related with CSU, and total IgE was associated with urticaria, ASST was found to be of importance. This study confirms that ASST was insufficient to demonstrate autoimmunity and acute-chronic urticaria nature. Further tests indicating auto-antibodies in AU and CSU are needed.

Eicosanoid mediator profiles in different phenotypes of nonsteroidal anti-inflammatory drug-induced urticaria

BACKGROUND

The role of arachidonic acid metabolites in NSAID-induced hypersensitivity has been studied in depth for NSAID-exacerbated respiratory disease (NERD) and NSAID-exacerbated cutaneous disease (NECD). However, no information is available for NSAID-induced urticarial/angioedema (NIUA), despite it being the most frequent clinical entity induced by NSAID hypersensitivity. We evaluated changes in leukotriene and prostaglandin metabolites for NIUA patients, using patients with NECD and single-NSAID-induced urticaria/angioedema or anaphylaxis (SNIUAA) for comparison.

METHODS

Urine samples were taken from patients with confirmed NSAID-induced urticaria and healthy controls, at baseline and at various time intervals after ASA administration. Eicosanoid measurement was performed using high-performance liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry.

RESULTS

No differences were found between groups at baseline. Following ASA administration, LTE4 and 9α,11β-PGF2 levels were increased in both NIUA and NECD patients compared to baseline, rising initially, before decreasing toward initial levels. In addition, the levels of these metabolites were higher in NIUA and NECD when compared with the SNIUAA and control groups after ASA administration. No changes were found with respect to baseline values for SNIUAA and control groups.

CONCLUSIONS

We present for the first time data regarding the role of COX-1 inhibition in NIUA. Patients with this entity show a similar pattern eicosanoid levels following ASA challenge to those with NECD. Further studies will help ascertain the cell populations involved and the underlying molecular mechanisms.

Chronic urticaria and drug hypersensitivity in children

The cause of chronic urticaria remains often elusive. The association between chronic urticaria and intake of medications have been reported in children. However, the causative role of drugs has been rarely ascertained by onset of symptoms on drug provocation test. Chronic urticaria can be mediated by immunologic and nonimmunologic mechanisms. The diagnostic work-up of chronic urticaria includes a comprehensive evaluation of triggering factors such as drugs. A diagnosis is necessary in order to permit a safely administration of drugs in children with chronic urticaria.

Multiple Drug Intolerance Syndrome: An Underreported Distinct Clinical Entity

Aim:

Multiple drug intolerance syndrome (MDIS) is a unique clinical entity distinct from other drug hypersensitivity syndromes. The aim of this review was to critically appraise the various aspects of MDIS.

Methods

A review was conducted to search for the causes, mechanism, clinical features, and management of MDIS.

Results

The most common cause of MDIS is antibiotics followed by non-steroidal anti-inflammatory drugs (NSAIDs). Although some non-specific immunological mechanisms are involved, the immunological tests for MDIS are negative. Rashes, gastrointestinal reflux, headache, cough, muscle ache, fever, dermatitis, hypertension, and psychiatric symptoms are the usual manifestations. Treatment is mostly symptomatic with the withdrawal of the offending drug. Drug re-challenges and desensitization may be required for the management of this syndrome.

Conclusion

MDIS occurs by a nonimmune mechanism which requires a prompt withdrawal of the offending drug(s), and in some cases may require drug re-challenge and desensitization.

Chronic urticaria: a focus on pathogenesis

Chronic urticaria is a spontaneous or inducible group of diseases characterized by the occurrence of wheals (and, in about half of cases, angioedema) for more than 6 weeks. These are rather frequent conditions that may severely affect patients’ quality of life and sometimes represent a challenge for doctors as well. The causes of chronic urticaria are still poorly defined, although there is growing evidence that different biologic systems including immunity, inflammation, and coagulation may take part in the pathomechanism eventually leading to mast cell and basophil degranulation and hence to wheal formation. This review will discuss the main findings that are (slowly) shedding light on the pathogenesis of this disorder.

Challenge-proven aspirin hypersensitivity in children with chronic spontaneous urticaria

BACKGROUND

Nonsteroidal anti-inflammatory drug (NSAID) exacerbated cutaneous disease is defined as the exacerbation of wheals and/or angioedema in patients with a history of chronic spontaneous urticaria (CSU). The objective of this study was to define 'aspirin-hypersensitive' children and adolescents in a clearly defined group of patients with CSU and to describe their clinical features.

METHODS

Eighty-one children with a history of CSU were enrolled over a 3-year period. The daily or almost daily (>4 days a week) presence of urticaria was defined as 'chronic persistent urticaria' (CPU), while the presence of urticaria for 2-4 days a week was defined as 'chronic recurrent urticaria' (CRU). Single-blind, placebo-controlled provocation tests (SBPCPTs) with aspirin were performed for children with CSU.

RESULTS

Patients with CRU had a longer duration of cutaneous symptoms [1.6 (0.5-4) vs 0.6 (0.3-1.5) years], and stress was less frequently experienced as an eliciting factor in patients with CRU compared with the patients with CPU (P < 0.016, P = 0.024, respectively). SBPCPTs with aspirin revealed that 14 of 58 patients (24%) with CPU and one of 10 patients with CRU (10%) were aspirin hypersensitive. Aspirin hypersensitivity rate was 26.5% in patients <12 years of age. All of the 15 aspirin-hypersensitive patients (aged between 6.6 and 17.4 years), except for three, experienced an unequivocal angioedema of the lips as a positive reaction in SBPCPT.

CONCLUSIONS

Nearly a quarter of children and adolescents with CSU were hypersensitive to aspirin. For children with chronic urticaria, determination of NSAID hypersensitivity in a well-controlled clinical setting will help to avoid severe drug hypersensitivity reactions.

The EAACI/GA(2) LEN/EDF/WAO Guideline for the definition, classification, diagnosis, and management of urticaria: the 2013 revision and update

This guideline is the result of a systematic literature review using the 'Grading of Recommendations Assessment, Development and Evaluation' (GRADE) methodology and a structured consensus conference held on 28 and 29 November 2012, in Berlin. It is a joint initiative of the Dermatology Section of the European Academy of Allergy and Clinical Immunology (EAACI), the EU-funded network of excellence, the Global Allergy and Asthma European Network (GA(2) LEN), the European Dermatology Forum (EDF), and the World Allergy Organization (WAO) with the participation of delegates of 21 national and international societies. Urticaria is a frequent, mast cell-driven disease, presenting with wheals, angioedema, or both. The life-time prevalence for acute urticaria is approximately 20%. Chronic spontaneous urticaria and other chronic forms of urticaria do not only cause a decrease in quality of life, but also affect performance at work and school and, as such, are members of the group of severe allergic diseases. This guideline covers the definition and classification of urticaria, taking into account the recent progress in identifying its causes, eliciting factors and pathomechanisms. In addition, it outlines evidence-based diagnostic and therapeutic approaches for the different subtypes of urticaria. This guideline was acknowledged and accepted by the European Union of Medical Specialists (UEMS).

Multiple nonsteroidal anti-inflammatory drug-induced cutaneous disease: what differentiates patients with and without underlying chronic spontaneous urticaria?

BACKGROUND

Multiple nonsteroidal anti-inflammatory drug (NSAID) cutaneous reactors may be otherwise normal or have underlying chronic spontaneous urticaria (CSU). This study compared these two phenotypes of NSAID-hypersensitive subjects.

METHODS

A total of 97 multiple NSAID reactors underwent oral challenges with paracetamol, etoricoxib and tramadol. Atopic status was investigated in all patients, and autoreactivity was ascertained in some cases as well. Otherwise normal multiple NSAID reactors were reevaluated after 1-5 years in order to detect their proneness to CSU.

RESULTS

At the first visit, 41 patients had CSU and 56 had multiple NSAID intolerance without any underlying cutaneous disease. Altogether, 22, 10 and 6% of patients did not tolerate paracetamol, etoricoxib and tramadol, respectively, on oral challenge. Intolerance to these alternative drugs showed a strong association (p < 0.01 with all combinations). The two subgroups of patients did not show any difference in terms of mean age, gender distribution, prevalence of atopic diseases, prevalence of single offending NSAIDs and prevalence of intolerance to paracetamol, etoricoxib or tramadol on oral challenge. In all, 20% of multiple NSAID reactors without CSU at presentation developed CSU between 6 months and 5 years after the initial clinical evaluation.

CONCLUSIONS

Multiple NSAID cutaneous reactors with or without CSU seem identical from a clinical point of view, and some of the latter group show a propensity to acquire the former phenotype over time. A subset of patients apparently identical to the general population of multiple NSAID reactors also react to drugs exerting little or no cyclooxygenase-1 enzyme inhibition and might represent a distinct phenotype of NSAID-hypersensitive patients possibly characterized by a different underlying pathogenesis.

Flow Cytometry-Assisted Basophil Activation Test as a Safe Diagnostic Tool for Aspirin/NSAID Hypersenstivity

Purpose

Aspirin and non-steroidal anti-inflammatory drugs (ASA/NSAIDs) are common causes of drug hypersensitivity. An oral provocation test is the only definitive diagnostic test. This study assessed the reliability of a flow cytometry-assisted basophil activation test (FAST) as a safe diagnostic method for ASA/NSAID-induced hypersensitivity, as its high sensitivity and specificity have been demonstrated for many other drugs.

Methods

Eighteen patients and 11 controls were enrolled. Using a Flow-CAST kit® (Bühlmann Laboratories AG, Schönenbuch, Switzerland), 29 analyses with aspirin, ibuprofen, and diclofenac were performed by flow cytometry to detect double-positive staining of anti-IgE and anti-CD63. The stimulation index was defined as the activated basophil percentage after drug stimulation/basally active basophil percentage. A stimulation index≥2 and an absolute activated basophil percentage≥5 were considered positive.

Results

Patients with hypersensitivity to ASA/NSAIDs were predominantly female, and the prevalence of atopy was higher in patients than in controls. A sensitivity of 61%, specificity of 91%, positive predictive value of 92%, and negative predictive value of 59% were achieved.

Conclusions

FAST is a useful additional method for diagnosis of hypersensitivity reactions to ASA/NSAIDs. Further development is required to increase the sensitivity of the test.

Markers of autoreactivity, coagulation and angiogenesis in patients with nonallergic asthma

BACKGROUND

Patients with nonallergic asthma frequently show autoreactivity as do subjects with chronic urticaria (CU). Activation of the coagulation cascade and hyper-expression of vascular endothelial growth factor (VEGF) were recently found in CU, and there is sparse evidence that the same may occur in asthma.

OBJECTIVE

To investigate autoreactivity, activation of the coagulation cascade, and expression of VEGF in patients with nonallergic asthma.

METHODS

Twenty-one adults with nonallergic asthma underwent autologous plasma skin test (APST) and the measurement of plasma levels of the prothrombin fragment F1+2, D-dimer, VEGF, and the inflammatory marker C-reactive protein (CRP). Twenty-one healthy sex- and age-matched subjects served as normal controls.

RESULTS

The APST scored positive in 19 of 21 (90%) patients vs 0 controls. Mean fragment F1+2 plasma levels were significantly higher in patients with asthma (267 ± 243 pM) than in controls (150 ± 51 pM; P = 0.0001). Similarly, plasma levels of both D-dimer and VEGF were significantly higher in patients than in controls (D-dimer: 2364 ± 1467 vs 1301 ± 525 pM; P = 0.0001; VEGF: 1721 ± 2566 vs 76 ± 375 fM; P = 0.0001). A trend toward increased levels of F1+2, D-dimer, VEGF, and CRP was found in patients with a more severe disease according to GINA classification.

CONCLUSION

Nonallergic asthma is characterized by autoreactivity as well as increased coagulation and angiogenesis markers, which are known to enhance vascular permeability. The presence of circulating vasoactive factors may be relevant to understand the disease pathophysiology and to detect novel therapeutic strategies in nonallergic asthma.

Diagnosis and management of drug hypersensitivity reactions

The present article addresses the advances in the diagnosis and management of drug hypersensitivity reactions that were discussed in the 4th Drug Hypersensitivity Meeting held in Rome in April 2010. Such reactions can be classified as immediate or nonimmediate according to the time interval between the last drug administration and onset. Immediate reactions occur within 1 hour, and nonimmediate reactions occur after more than 1 hour. Clinical and immunologic studies suggest that type-I (IgE-mediated) and type-IV (T cell-mediated) pathogenic mechanisms are involved in most immediate and nonimmediate reactions, respectively. In diagnosis prick, patch, and intradermal tests are the most readily available tools. Determination of specific IgE levels is still the most common in vitro method for diagnosing immediate reactions. New diagnostic tools, such as the basophil activation test, the lymphocyte activation test, and enzyme-linked immunospot assays for analysis of the frequency of antigen-specific, cytokine-producing cells, have been developed for evaluating either immediate or nonimmediate reactions. The sensitivity of allergologic tests is not 100%; therefore in selected cases provocation tests are necessary. In the diagnosis of nonallergic hypersensitivity reactions to nonsteroidal anti-inflammatory drugs, the provocation test with the suspected drug still represents the "gold standard." However, there was no consensus regarding the use of this test in subjects with histories of hypersensitivity reactions to 1 (single reactors) or more (multiple reactors) nonsteroidal anti-inflammatory drugs. With regard to management, desensitization allows patients to be treated with irreplaceable chemotherapy agents, such as taxanes, platinum salts, and mAbs, to which they have presented hypersensitivity reactions. Desensitization also permits the use of aspirin in aspirin-sensitive patients undergoing revascularization and in subjects with aspirin-exacerbated respiratory disease.

Drug allergy: an updated practice parameter

Adverse drug reactions (ADRs) result in major health problems in the United States in both the inpatient and outpatient setting. ADRs are broadly categorized into predictable (type A and unpredictable (type B) reactions. Predictable reactions are usually dose dependent, are related to the known pharmacologic actions of the drug, and occur in otherwise healthy individuals, They are estimated to comprise approximately 80% of all ADRs. Unpredictable are generally dose independent, are unrelated to the pharmacologic actions of the drug, and occur only in susceptible individuals. Unpredictable reactions are subdivided into drug intolerance, drug idiosyncrasy, drug allergy, and pseudoallergic reactions. Both type A and B reactions may be influenced by genetic predisposition of the patient

Autologous serum skin test reactivity and basophil histamine release test in patients with nasal polyposis: preliminary results

An eosinophilic inflammatory process is generally observed in patients suffering from nasal polyposis (NP), however its onset has not yet been defined. It has been suggested that immune activation of inflammatory cells may be the cause. The aim of this study is to verify whether autoantibodies and/or histamine-releasing factors are present in the serum of patients suffering from NP. In fact, we assume that autoantibodies and/or histamine-releasing factors, as already demonstrated in chronic idiopathic urticaria and asthma, may be involved in the pathogenesis of NP. In this case-control analytical study 40 patients with NP and 27 control subjects underwent the in vivo autologous serum skin test (ASST). The sera from 6 patients suffering from NP and 9 control group subjects, who had all been previously studied and randomly selected, underwent basophil histamine release assay from normal donor as a pilot study. The ASST showed positive results in 55% of patients suffering from NP versus 8% of the control group (p= .00006), the basophil histamine release test (BHRT) turned out positive in all patients tested and in 11% of the control group. We found a weak positive correlation between the percentage of histamine release and the wheal diameter. ASST reactivity is very frequent in patients suffering from NP, thus suggesting the presence of histamine-releasing factors in the blood stream. The BHRT was positive in the serum of all patients, thus suggesting the presence of anti-FcepsilonRI, anti-IgE autoantibodies and/or other histamine-releasing factors, the presence of which can play a role in triggering and maintaining the eosinophilic inflammatory process in NP.

EAACI/GA(2)LEN/EDF/WAO guideline: definition, classification and diagnosis of urticaria

This guideline, together with its sister guideline on the management of urticaria [Zuberbier T, Asero R, Bindslev-Jensen C, Canonica GW, Church MK, Giménez-Arnau AM et al. EAACI/GA(2)LEN/EDF/WAO Guideline: Management of urticaria. Allergy, 2009; 64:1427-1443] is the result of a consensus reached during a panel discussion at the 3rd International Consensus Meeting on Urticaria, Urticaria 2008, a joint initiative of the Dermatology Section of the European Academy of Allergology and Clinical Immunology (EAACI), the EU-funded network of excellence, the Global Allergy and Asthma European Network (GA(2)LEN), the European Dermatology Forum (EDF) and the World Allergy Organization (WAO). Urticaria is a frequent disease. The life-time prevalence for any subtype of urticaria is approximately 20%. Chronic spontaneous urticaria and other chronic forms of urticaria do not only cause a decrease in quality of life, but also affect performance at work and school and, as such, are members of the group of severe allergic diseases. This guideline covers the definition and classification of urticaria, taking into account the recent progress in identifying its causes, eliciting factors, and pathomechanisms. In addition, it outlines evidence-based diagnostic approaches for different subtypes of urticaria. The correct management of urticaria, which is of paramount importance for patients, is very complex and is consequently covered in a separate guideline developed during the same consensus meeting. This guideline was acknowledged and accepted by the European Union of Medical Specialists (UEMS).

C5a-induced in vitro basophil activation in patients with chronic urticaria: a pilot study

BACKGROUND

Complement component 5a (C5a) might be involved in the formation of wheals in patients with chronic urticaria (CU). We sought to compare the in vitro responsiveness of basophils to C5a in patients with CU and in a control group.

METHODS

Basophil surface expression of activation marker CD63 induced by C5a, anti-FcepsilonRI mAb or anti-IgE pAb was measured using flow cytometry in 17 patients with CU and in 10 healthy controls.

RESULTS

Patients with CU showed significantly greater basophil CD63 surface expression induced by C5a (median [interquartile range]; 16.4% [13-25.1]; P = 0.011) than the group of healthy controls (10.7% [7.2-16.8]). In contrast, basophil CD63 response to anti-IgE and anti-FcepsilonRI was lower in the CU group (12.3% [6-36.3]; 25.9% [12.5-60.5]) than in the control group (51.7% [6.7-84.3]; 62.1% [9.7-89.2]), although not statistically significant.

CONCLUSION

Results of this pilot study suggest that patients with CU might have an enhanced basophil response to stimulation with C5a, indicating that further studies in CU basophil responsiveness are needed.

EAACI/GA(2)LEN task force consensus report: the autologous serum skin test in urticaria

Injection of autologous serum collected during disease activity from some patients with chronic spontaneous urticaria (CU) into clinically normal skin elicits an immediate weal and flare response. This observation provides a convincing demonstration of a circulating factor or factors that may be relevant to the understanding of the pathogenesis and management of the disease. This test has become known as the autologous serum skin test (ASST) and is now widely practised despite incomplete agreement about its value and meaning, the methodology and the definition of a positive response. It should be regarded as a test for autoreactivity rather than a specific test for autoimmune urticaria. It has only moderate specificity as a marker for functional autoantibodies against IgE or the high affinity IgE receptor (FcepsilonRI), detected by the basophil histamine release assay, but high negative predictive value for CU patients without them. It is usually negative in other patterns of CU, including those that are physically induced. Positive ASSTs have been reported in some subjects without CU, including those with multiple drug intolerance, patients with respiratory allergy and healthy controls, although the clinical implications of this are uncertain. It is essential that failsafe precautions are taken to ensure that the patient's own serum is used for skin testing and aseptic procedures are followed for sample preparation and handling. CU patients with a positive ASST (ASST(+)) are more likely to be associated with HLADR4, to have autoimmune thyroid disease, a more prolonged disease course and may be less responsive to H1-antihistamine treatment than those with a negative ASST (ASST(-)) although more evidence is needed to confirm these observations conclusively.

[Safety of reintroducing platelet-inhibitory doses of aspirin in patients with urticaria or angioedema induced by anti-inflammatory doses]

BACKGROUND

Aspirin is one of the most widely prescribed drugs in the world on account of its analgesic, antipyretic, and anti-inflammatory properties. Its effect on platelet aggregation makes it the first choice for prophylaxis in cardiovascular, neurological and obstetric diseases. However, a history of aspirin-induced urticaria and/or angioedema is usually a contraindication for further prescription of the drug. The aim of this article was to demonstrate that patients presenting aspirin-induced cutaneous reactions at anti-inflammatory doses can safely benefit from aspirin reintroduction at platelet-inhibitory doses.

PATIENTS AND METHODS

Patients with a history of aspirin-induced urticaria and/or angioedema referred to our department between January 2000 and June 2008 for double-blind placebo-controlled reintroduction at platelet-inhibitory doses for a medical indication were enrolled in this study.

RESULTS

Seventy patients with aspirin hypersensitivity as well as a medical indication for this therapy were referred to our department. Of these, 38 (54.3%) had a history of aspirin-induced urticaria and/or angioedema, including three laryngeal oedemas (7.9%). All subjects received platelet-inhibitory doses of aspirin (maximal total dose: 400mg/day) in double-blind placebo-controlled fashion during a one-day hospitalization period. None of the patients presented an immediate hypersensitivity reaction. Only one patient, who had received a cumulative dose of 200mg/day, reported diffuse urticaria and facial angioedema of no clinical significance the following day. He had a history of chronic urticaria.

CONCLUSION

This article demonstrates the safety of reintroducing platelet-inhibitory doses of aspirin in patients in whom it is indicated and reporting aspirin-induced urticaria and/or angioedema with anti-inflammatory doses. However, patients with a history of chronic urticaria should undergo a challenge with the lowest platelet-inhibitory dose (75mg/day) in order to minimize the risk of aggravating their condition.

Evaluation of autologous serum skin test results in patients with chronic idiopathic urticaria, allergic/non-allergic asthma or rhinitis and healthy people

BACKGROUND

Recent data indicate that the autologous serum skin test (ASST) shows a high rate of reactivity not only in chronic idiopathic urticaria (CIU) but also in cases with non-allergic asthma and rhinitis (NAAR), multiple drug allergy syndrome (MDAS) and even in some healthy people. Aim. To evaluate ASST reactivity in patients with CIU, allergic/non-allergic asthma or rhinitis and in healthy controls.

METHODS

We studied 80 patients with CIU, 40 non-atopic patients with NAAR, 57 patients with allergic rhinitis (AR) and allergic bronchial asthma (ABA), and 45 healthy controls. ASST was performed in all patients and controls, and it was considered positive when a serum-induced weal with a diameter 1.5 mm greater than the negative (saline) control, surrounded by erythema, was present.

RESULTS

In total, 42 patients with CIU showed ASST reactivity (52.5%). ASST was found to be positive in 8 of 40 patients with NAAR (20%). The rate was similar (17.5%) in the AR/ABA patient group. However, 25 healthy controls (55.5%) also had positive ASST. The highest rate was in female controls and in individuals in the 18-30-year-old age group.

CONCLUSION

The data indicate that ASST positivity might be a nonspecific phenomenon, influenced by many factors. In the light of the results of this study, we suggest that the significance of ASST reactivity should be re-evaluated in CIU. In addition, the importance of ASST reactivity in patients with AR/ABA and in patients with NAAR remains unclear, and further controlled studies are needed.

Predictive Value of Autologous Plasma Skin Test for Multiple Nonsteroidal Anti-Inflammatory Drug Intolerance

BACKGROUND

Recent studies show that patients with multiple nonsteroidal anti-inflammatory drug (NSAID) intolerance are frequently characterized by autoreactivity; this can be detected by autologous serum skin test (ASST).

OBJECTIVE

To assess whether the autologous plasma skin test (APST), a test that was recently shown to be more sensitive than ASST, may be usefully employed as a predictive test for multiple NSAID intolerance in patients with a history of single NSAID intolerance.

METHODS

Thirty otherwise normal adults with a history of acute urticaria following the ingestion of one single NSAID underwent an APST before being challenged with a COX-1-inhibiting NSAID other than the offending drug.

RESULTS

Sixteen patients experienced urticaria following the ingestion of the alternative NSAID and were therefore classified as multiple NSAID reactors; all 16 (100%) scored positive on APST. In contrast only 3/14 patients finally classified as single NSAID reactors were positive on APST (p < 0.001). The positive and negative predictive value of APST for multiple NSAID intolerance were 86 and 100%, respectively.

CONCLUSION

In patients with a history of acute urticaria induced by a single NSAID APST can be usefully employed to detect patients that are prone to react to NSAID other than the original offending one.

Safety of selective cyclooxygenase-2 inhibitors and a basic non-steroidal anti-inflammatory drug (NSAID) in Japanese patients with NSAID-induced urticaria and/or angioedema: Comparison of meloxicam, etodolac and tiaramide

The identification of a safe and reliable alternative for patients with non-steroidal anti-inflammatory drug (NSAID)-induced urticaria/angioedema is a frequent problem for dermatologists and other practitioners. Cyclooxygenase-2 (COX-2) inhibitors have been reported to be safe for NSAID-intolerant patients from the US and Europe but not all of them have yet been approved for use in Japan. It was our objective to investigate the clinical manifestations of oral NSAID challenges in Japanese patients with histories of urticaria and/or angioedema after the intake of NSAIDs and to find safe alternative drugs, including COX-2 inhibitors and a basic anti-inflammatory drug. Twenty subjects suspected NSAID-induced urticaria/angioedema from histories were included in a double-blind or single-blind, placebo-controlled oral challenge protocol using NSAIDs. Skin prick tests using NSAIDs, which were dissolved in saline, were conducted. The mean age of the patients was 37.3 years; 14 patients were female. The results of other challenge tests showed that the most frequently intolerated drugs was loxoprofen (100%), followed by acetyl salicylic (94.4%), etodolac (53.3%), dicrofenac (50%), acetaminophen (38.5%), meloxicam (33%), and tiaramide (21.4%). Urticaria and angioedema were induced after aspirin intake in 83.3% and 22.2% of patients, respectively, whereas an asthmatic response was seen in 5.6%. Skin prick tests with NSAIDs were 100% negative. This study showed that among the NSAIDs that are available in Japan and that were investigated in this study, tiaramide, which does not inhibit COX, is the relatively safe alternative drug for Japanese patients with NSAID-induced urtiacaria and/or angioedema. Furthermore, meloxicam seems to be better tolerated than etodolac between two selective COX-2 inhibitors.

Tolerance to coxibs in patients with intolerance to non-steroidal anti-inflammatory drugs (NSAIDs): a systematic structured review of the literature

Adverse events triggered by non-steroidal anti-inflammatory drugs (NSAIDs) are among the most common drug-related intolerance reactions in medicine; they are possibly related to inhibition of cyclooxygenase-1. Coxibs, preferentially inhibiting cyclooxygenase-2, may therefore represent safe alternatives in patients with NSAID intolerance. We reviewed the literature in a systematic and structured manner to identify and evaluate studies on the tolerance of coxibs in patients with NSAID intolerance. We searched MEDLINE (1966–2006), the COCHRANE LIBRARY (4th Issue 2006) and EMBASE (1966–2006) up to December 9, 2006, and analysed all publications included using a predefined evaluation sheet. Symptoms and severity of adverse events to coxibs were analysed based on all articles comprising such information. Subsequently, the probability for adverse events triggered by coxibs was determined on analyses of double-blind prospective trials only. Among 3,304 patients with NSAID intolerance, 119 adverse events occurred under coxib medication. All adverse events, except two, have been allergic/urticarial in nature; none was lethal, but two were graded as life-threatening (grade 4). The two non-allergic adverse events were described as a grade 1 upper respiratory tract haemorrhage, and a grade 1 gastrointestinal symptom, respectively. In 13 double-blind prospective studies comprising a total of 591 patients with NSAID intolerance, only 13 adverse reactions to coxib provocations were observed. The triggering coxibs were rofecoxib (2/286), celecoxib (6/208), etoricoxib (4/56), and valdecoxib (1/41). This review documents the good tolerability of coxibs in patients with NSAID intolerance, for whom access to this class of drugs for short-term treatment of pain and inflammation is advantageous.

Clinical management of adult patients with a history of nonsteroidal anti-inflammatory drug-induced urticaria/angioedema: update

In the large majority of previous studies, patients with a history of acute urticaria induced by nonsteroidal anti-inflammatory drugs (NSAIDs) seeking safe alternative drugs have undergone tolerance tests uniquely with compounds exerting little or no inhibitory effect on the cyclooxygenase 1 enzyme. In light of recently published studies, however, this approach seems inadequate and should be changed. The present article critically reviews the clinical management of patients presenting with a history of urticaria induced by a single NSAID or multiple NSAIDs and suggests a simple, updated diagnostic algorithm that may assist clinicians in correctly classifying their patients.

Tolerance to etoricoxib in 37 patients with urticaria and angioedema induced by nonsteroidal anti-inflammatory drugs

BACKGROUND

The use of cyclooxygenase-2 inhibitors, a new class of analgesic drugs, is suggested in patients with hypersensitivity to nonsteroidal anti-inflammatory drugs (NSAIDs).

OBJECTIVE

To evaluate tolerance to etoricoxib, a new cyclooxygenase-2 inhibitor, in NSAID-sensitive patients with urticaria-type adverse reactions.

PATIENTS

Thirty-seven patients with adverse reactions to NSAIDs.

METHODS

Single-blind, placebo-controlled oral challenge with increasing doses of etoricoxib.

RESULTS

Thirty-four patients tolerated etoricoxib treatment without adverse reactions, but a generalized urticarial rash developed in 3 patients (8%).

CONCLUSIONS

Etoricoxib, like other cyclooxygenase-2 inhibitors, is a well-tolerated drug in most NSAID-sensitive patients. However, according to our experience, a previous challenge test in a safe environment may be necessary before prescribing the drug to such patients.

Chronic idiopathic urticaria with functional autoantibodies: 12 years on

It is now recognized that approximately one-third of patients with chronic idiopathic urticaria (CIU) have histamine-releasing autoantibodies directed against either the high-affinity IgE receptor or, less frequently, against IgE. However, there are several unsolved problems relating to the role of such autoantibodies in the disease. Additionally, it is not clear whether CIU with autoantibodies can be classified as an autoimmune disease. The detection of patients with autoantibodies also poses challenges. Firstly, the only in vivo method, the autologous serum skin test, is at best 80% sensitive and specific using in vitro basophil histamine release assays as the verum. Secondly, in vitro tests are only done in a small number of research laboratories, and are not widely commercially available, and thirdly, there is some divergence between results obtained by different methods (functional and immunoassays) used to detect patients with autoantibodies. The presence of autoantibodies may be important clinically in a small group of severely affected, treatment-resistant patients, where immunomodulatory treatments may be helpful.

The broken balance in aspirin hypersensitivity

Aspirin was introduced into medicine over a century ago and has become the most popular drug in the world. Although the first hypersensitivity reaction was described soon after aspirin had been marketed, only recently a phenomenon of cysteinyl leukotriene overproduction brought new insights on a balance between pro- and anti-inflammatory mediators derived from arachidonic acid. We describe the most common clinical presentations of aspirin hypersensitivity, i.e. aspirin-induced asthma, rhinosinusitis and aspirin-induced urticaria. We also present their biochemical background. Despite relatively high incidence of these reactions, aspirin hypersensitivity remains underdiagnosed worldwide. Acute reactions of aspirin hypersensitivity are elicited via cyclooxygenase inhibition by non-steroid anti-inflammatory drugs. Coxibs, selective inhibitors of cyclooxygenase-2 isoenzyme, do not precipitate symptoms in susceptible patients. Though hypersensitivity correlates with cyclooxygenase-1 inhibition, diminished tissue expression was described only for cyclooxygenase-2. Aspirin-induced asthma and aspirin-induced urticaria, in a substantial part of the patients, are driven by a release of mediators from activated mast cells. These cells in physiological conditions are under inhibitory control of prostaglandin E2. The origin of aspirin hypersensitivity remains unknown, but accumulating data from genetic studies strongly suggest that environmental factor, possibly a common viral infection, can trigger the disease in susceptible subjects.

Autologous serum skin test reactivity in patients with non-allergic asthma

BACKGROUND

Inflammatory alterations of respiratory airways have been found in patients with non-allergic asthma, but the triggering event has not been defined. An autoimmune activation of inflammatory cells has been hypothesized.

OBJECTIVE

To evaluate whether histamine-releasing factors are present in sera from non-allergic asthmatics.

METHODS

Twenty-four patients with non-allergic asthma underwent in vivo autologous serum skin test (ASST) and in vitro basophil histamine release assay using autologous basophils as well as basophils from normal donors. Twenty-seven subjects with respiratory allergy and three normal subjects were chosen as control.

RESULTS

ASST was positive in 14/24 non-allergic asthmatics (58%) whereas it was negative in all 30 control subjects (P<0.001). The serum of only one ASST-positive patient out of 12 (8.4%) induced in vitro histamine release from autologous basophils. The serum from another ASST-positive patient induced histamine release from membrane IgE-stripped autologous basophils. Sera from either non-allergic asthmatics or from control subjects did not provoke significant histamine release from basophils from three normal donors.

CONCLUSION

Skin reactivity to autologous serum is common among non-allergic asthmatics, indicating the presence of circulating histamine-releasing factors. However, only in a minority of patients in vitro functional evidence of histamine-releasing autoantibodies (anti-FcepsilonRI or anti-IgE) was obtained. The presence of circulating histamine-releasing factors might contribute to initiation/maintenance of inflammation in respiratory airways of non-allergic asthmatics.

Mechanism of chronic urticaria exacerbation by aspirin

In some patients with chronic idiopathic urticaria (CIU), aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) that inhibit cyclooxygenase 1 (COX-1) precipitate wheals and swelling. There is no in vitro diagnostic, and diagnosis can be established only by provocation challenges with aspirin or other NSAIDs. Skin reactions triggered by aspirin are associated with the inhibition of cyclooxygenase, specifically COX-1, but not COX-2, and are characterized by overproduction of cysteinyl leukotrienes (cys-LTs). Aspirin and other NSAIDs should be avoided, but highly specific COX-2 inhibitors, known as coxibs, are well tolerated and can probably be safely used. Evidence has been accumulated that these reactions are due to the interference of aspirin-like drugs with arachidonic-acid metabolism. In this article, we discuss the mechanism of these reactions, and the characteristic course of aspirin-induced urticaria and its management.

Risk of skin reactions when using ibuprofen-based medicines

Adverse reactions to drugs are a frequent cause of morbidity and medical consultation; it is no surprise that nonsteroidal anti-inflammatory drugs (NSAIDs) run second, after antibiotics, mainly of the beta-lactam group (penicillins and cephalosporins). Numerous clinical pictures involving the skin--various morbilliform rashes, urticaria and angioedema as the most common--due to hypersensitivity to a particular NSAID (i.e., ibuprofen) have been described; other clinically defined skin diseases such as vasculitis, Steven-Johnson's syndrome, photosensitivity, fixed drug eruptions, livedo-like dermatitis, linear drug eruption, lichenoid drug eruption, exanthematous pustulosis, eczematous eruption, contact dermatitis and pemphigoid have received the attention of physicians. Extensive use around the world makes it interesting to investigate adverse cutaneous reactions to ibuprofen and other members of the propionic acid derivative group, to ascertain their prevalence, clinical presentation and prevention. This paper presents a review of published literature concerning cutaneous hypersensitivity reactions to ibuprofen and related arylpropionic acids.

Oral aspirin challenges in patients with a history of intolerance to single non-steroidal anti-inflammatory drugs

Summary Background In the clinical practice patients with a history of acute urticaria induced by a single non-steroidal anti-inflammatory drug (NSAID) and seeking for safe alternative drugs generally undergo tolerance tests with alternative NSAIDs that have little or no cyclooxygenase-1 (COX-1) enzyme inhibitory activity. This practice does not allow for the detection of single NSAID reactors and may lead to unnecessary avoidance of many potentially useful NSAIDs.

OBJECTIVE

Evaluate aspirin challenge as a means to distinguish single from multiple NSAID intolerance in patients with a clinical history of acute urticaria induced by a single NSAID. Methods One hundred and seventeen otherwise normal subjects with a history of acute urticaria following the ingestion of a single NSAID (pyrazolones (n=58), nimesulide (n=17), propionic acid derivatives (n=13), aryl acetic acid derivatives (n=14), acetaminophen (n=9), piroxicam (n=5), and indometacin (n=1)) underwent single-blind placebo-controlled oral challenges with aspirin. Aspirin-intolerant subjects underwent further tolerance tests drugs exerting little or no inhibitory activity on COX-1 enzyme (including paracetamol, nimesulide, rofecoxib, tramadol, and floctafenine). Results Aspirin induced urticaria in 28/117 (24%) patients. Five out of 28 (18%) aspirin reactors did not tolerate alternative NSAID on subsequent oral challenges. Conclusion In subjects with a history of urticaria induced by a single NSAID (other than aspirin) the diagnostic workup should start with an aspirin challenge in order to detect single/multiple NSAID reactors.

Drug-induced urticaria

Urticaria is characterised by transient swellings of the skin, which fluctuate over hours. Deeper swellings of the subcutaneous and submucosal tissue are known as angio-oedema. Drug-induced urticaria has been reported with a wide range of drugs and vaccines. NSAIDs and antibiotics are the drugs most commonly associated with urticaria, although reliable data from prospectively controlled studies is scarce. Spontaneous reports of drug-induced urticaria to the Committee on Safety of Medicines, UK, over a 40-year period also implicate bupropion, selective serotonin re-uptake inhibitor antidepressants, angiotensin-converting enzyme inhibitors (ACEI), H2 and H1 antihistamines, and systemic antifungals. New evidence suggests that selective COX-2 inhibitors may be tolerated in patients with aspirin-sensitive urticaria. The safety of angiotensin II receptor antagonists in patients with angio-oedema induced by ACEI has not yet been established.

Chronic urticaria and infections

PURPOSE OF REVIEW

The pathogenesis of chronic urticaria is multifactorial and a specific treatment is lacking. In acute urticaria there is no doubt of a causal relationship with infections and all chronic urticaria must start as the acute form. However, in the chronic form a primary role for infection is controversial, although it is undeniable that concurrent infections exacerbate the condition. This is the first English language review based on a detailed analysis of current peer-reviewed publications dealing with infections and chronic urticaria.

RECENT FINDINGS

In chronic urticaria there is a lot of evidence for different infections, but randomized controlled trials are missing. The prevalence of infections is not increased but in susceptible patients the immune response may lead to the development of chronic urticaria. Interestingly, there is evidence for an infection-associated autoreactive response at least in the subgroup with a positive autologous serum skin test. A variety of mechanisms have been invoked to explain these observations, including molecular mimicry.

SUMMARY

Actually the arguments for an important role of underlying causal infections in chronic urticaria are weak, from an evidence-based viewpoint, but there are data suggesting a link. Moreover, an association with underlying or precipitating infectious causes is difficult to establish because there is no possibility for challenge and the number of other urticarial triggers is vast. For the future it will be necessary to reveal the link between urticaria, autoreactivity, non-immunoglobulin E-mediated hypersensitivity reactions and infections to find attractive and specific therapeutic interventions for urticarial symptomatology.

Autoimmune urticaria

A growing body of evidence shows that at least 40% of patients with unexplained (idiopathic) chronic urticaria have clinically relevant functional autoantibodies to the high-affinity IgE receptor on basophils and mast cells. The term "autoimmune urticaria" is used for this subgroup of patients presenting with continuous ordinary urticaria. This article reviews the evidence for the autoimmune hypothesis and other nonantibody serum histamine-releasing factors in the etiopathogenesis of urticaria; defines autoimmune urticaria; looks at how autoimmune urticaria fits into existing classifications of urticaria; proposes diagnostic criteria that may be useful to the clinician; and reviews the management implications for patients with this subset of chronic disease.

Multiple NSAID intolerance in chronic idiopathic urticaria is correlated with delayed, pronounced and prolonged autoreactivity

Autologous serum skin test (ASST) reactivity is positive in up to 60% of patients with chronic idiopathic urticaria (CIU). About 21 to 30% of patients with CIU have intolerance to acetyl salicylic acid (ASA) and/or other chemically unrelated non-steroidal anti-inflammatory drugs (NSAIDs). To investigate the relationship between ASA/NSAID intolerance and ASST reactivity, a case-control study was performed in 110 patients with CIU and 60 healthy controls. A positive ASST was defined as an erythematous wheal with a diameter of > 5 mm more than the saline-induced response. Patients were assessed at 10-minute intervals for a minimum of three hours. ASA/NSAID intolerance was ascertained by a placebo controlled-provocation test with offending drug (s). Forty-two patients with CIU (38.2%) had autoreactivity whereas only two of the controls (3.3%) displayed early and weak skin responses (P<.0001). ASA/NSAID intolerance was demonstrated in 30 (27.3%) patients with CIU. The prevalences of autoreactivity were 93.3% (28/30) and 17.5% (14/80) in patients with and without ASA/NSAID intolerance, respectively (P<.001). Thirteen of the 25 ASST-positive patients (52%) who had single (n: 7) or multiple (n: 6) NSAID intolerance showed early (before or at 30 min) and mild autoreactivity of short duration, whereas 15 of the remaining 17 ASST-positive patients (88.2%) who all had multiple NSAID intolerance showed delayed (later than 30 min) and prolonged autoreactivity (P<.05). These findings suggest that a common mechanism may be responsible for the pathogeneses of both delayed autoreactivity and multiple NSAID intolerance in CIU. It might be further speculated that delayed, prolonged, and pronounced autoreactivity may be a possible predictor for multiple NSAID sensitivity in CIU.

Hypersensitivity to aspirin: common eicosanoid alterations in urticaria and asthma

BACKGROUND

Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) can precipitate adverse reactions in two apparently different clinical conditions: bronchial asthma and chronic idiopathic urticaria (CIU). Recent evidence indicates that the reactions are triggered by the drugs that inhibit cyclooxygenase-1 but not cyclooxygenase-2.

OBJECTIVE

To assess whether patients with CIU and aspirin sensitivity share common eicosanoid alterations with patients who have aspirin-sensitive asthma.

METHODS

Seventy-four patients with CIU and a history of sensitivity to aspirin and NSAIDs underwent placebo-controlled oral aspirin challenge tests. Concentrations of urinary leukotriene E4 (uLTE4) were measured by ELISA and plasma stable prostaglandin D2 metabolite, 9alpha,11beta prostaglandin F(2) by GC/MS. All measurements were carried out at baseline and after aspirin dosing. Patients were genotyped for the leukotriene C4 synthase (LTC4S) promoter single nucleotide polymorphism.

RESULTS

In 30 of 74 patients, the aspirin challenge was positive, resulting in urticaria/angioedema. In these 30 patients, baseline uLTE4 levels were higher than in nonresponders and the healthy control subjects and increased further (significantly) after the onset of clinical reaction. No such increase occurred in subjects with negative aspirin challenge. Baseline uLTE4 levels correlated with severity of skin reactions. Plasma 9alpha,11beta prostaglandin F(2) levels rose significantly in both aspirin responders and nonresponders, although in the latter group the increase occurred later than in the former. In patients who reacted to aspirin, frequency of (-444)C allele of LTC4S was significantly higher than in patients who did not react.

CONCLUSIONS

CIU with aspirin sensitivity is characterized by the eicosanoid alterations, which are similar to those present in aspirin-induced asthma.

Aspirin intolerance and the cyclooxygenase-leukotriene pathways

PURPOSE OF REVIEW

In up to 10% of patients with bronchial asthma, aspirin and other nonsteroidal antiinflammatory drugs precipitate asthmatic attacks. This is a hallmark of a distinct clinical syndrome that develops according to a characteristic sequence of symptoms. Here we discuss its clinical picture and management as related to the abnormalities in arachidonic acid transformations.

RECENT FINDINGS

At the biochemical level, the characteristic feature is profound alteration in eicosanoid biosynthesis and metabolism. Major advances in the molecular biology of eicosanoids, exemplified by the cloning of cysteinyl-leukotriene receptors and discovery of a whole family of cyclooxygenase enzymes, offer new insights into mechanisms operating in aspirin-induced asthma. Clinical interest has been enhanced by the introduction into therapy of highly specific cyclooxygenase-2 inhibitors and antileukotriene drugs.

SUMMARY

Recent studies have improved our understanding of mechanisms operating in asthma and unvieled the role of eicosanoid mediators in pulmonary disease.

Intolerance to nonsteroidal anti-inflammatory drugs might precede by years the onset of chronic urticaria

BACKGROUND

Recent studies have found that most otherwise normal subjects with a history of acute urticaria induced by several nonsteroidal anti-inflammatory drugs (NSAIDs) show a wheal-and-flare reaction on intradermal injection of autologous serum. This phenomenon has been previously observed in patients with chronic urticaria (CU) and suggests a possible common background in CU and NSAID-induced urticaria. A relationship between these 2 conditions is further suggested by the fact that up to 30% of patients with CU have a worsening of their skin disorders after the ingestion of chemically unrelated NSAIDs.

OBJECTIVE

I sought to assess whether otherwise normal subjects with multiple or single NSAID intolerance show a propensity to have CU.

METHODS

Two hundred eighty otherwise normal patients with an unequivocal history of acute urticaria induced by NSAIDs seen during the last 10 years were studied. On the basis of both clinical history and oral challenge tests with at least 2 alternative NSAIDs, the patients were classified as having single or multiple NSAID intolerance. All the patients were re-evaluated within the end of 2002, 1 to 10 years after the first visit, to assess the onset of CU. One hundred allergic adults without a history of CU and of drug allergy followed up for 1 to 10 years were used as control subjects.

RESULTS

One hundred fifty-nine and 121 patients were finally considered as having single or multiple NSAID intolerance, respectively. At the follow-up visit, 93 (33%) of 280 patients had CU. The prevalence of CU was very similar in subjects with single or multiple NSAID intolerance (48/159 [30%] vs 45/121 [37%], respectively; P = not significant). Only 1 (1%) of 100 atopic control subjects had CU during the follow-up period (P <.001). Among single NSAID reactors, patients who had CU had a significantly higher prevalence of intolerance to aspirin than those who did not have CU (36/48 [75%] vs 41/111 [37%], P <.001), whereas the latter had a markedly higher prevalence of intolerance to pyrazolone drugs (52/111 [47%] vs 10/48 [21%], P <.01). Altogether, only 12 (15%) of 82 patients intolerant to drugs other than aspirin versus 36 (47%) of 77 aspirin reactors had CU (P <.001).

CONCLUSION

NSAID intolerance might precede the onset of CU by years. Both multiple and single NSAID reactors with a history of aspirin-induced urticaria seem at higher risk for CU than patients with a history of single intolerance to NSAIDs other than aspirin.

Aspirin sensitivity and urticaria

The relationship of aspirin sensitivity to urticaria is complex. Aspirin sensitivity can cause acute urticaria in some individuals, aggravate pre-existing chronic urticaria in others or, rarely, act as a cofactor with food or exercise to provoke anaphylaxis. Individuals who react with urticaria appear to come from a different population to those who react with asthma, although there is some overlap. Aspirin-sensitive chronic urticaria patients may also react adversely to some food additives. The pharmacological mechanisms of aspirin-sensitive urticaria are not fully understood but probably involve diversion of arachidonic acid metabolism from prostaglandin to cysteinyl leukotriene formation leading to direct effects on blood vessels and delayed mast cell degranulation with release of histamine. Cross-reactivity amongst all nonsteroidal drugs is common in aspirin-aggravated chronic urticaria but appears not to occur with selective cyclo-oxygenase 2 inhibitors.