Epidemiology of hypersensitivity drug reactions

Immunologic evaluation of drug allergy

Hypersensitivity drug reactions (HDR) consist of an individual abnormal response with the involvement of the immunological system. In addition to specific immunological mechanisms where specific antibodies or sensitised T cells participate, release of inflammatory mediators by non-specific immunological recognition may also occur. Within this category are one of the most common groups of drugs, the non-steroidal anti-inflammatory drugs. In addition to chemical drugs new emerging ones with an increasing protagonism are biological agents like humanised antibodies and others. For IgE dependent reactions both in vivo and in vitro tests can be used for the immunological evaluation. Sensitivity of these is not optimal and very often a drug provocation test must be considered for knowing the mechanism involved and/or establishing the diagnosis. For non-immediate reactions also both in vivo and in vitro tests can be used. Sensitivity for in vivo tests is generally low and in vitro tests may be needed for the immunological evaluation. Immunohistochemical studies of the affected tissue enable a more precise classification of non-immediate reactions. The monitorization of the acute response of the reactions has given clues for understanding these reactions and has promising results for the future of the immunological evaluation of HDR.

Recent advances in the genetics and immunology of Stevens-Johnson syndrome and toxic epidermal necrosis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrosis (TEN) are rare but life-threatening severe cutaneous adverse reactions (SCARs), which are majorly (65-75%) induced by a variety of drugs. SJS/TEN could be recognized as SCARs or drug immune reactions, if the reactions are elicited by drugs. The recent studies suggested that SJS/TEN is a specific immune reaction initiated by the cytotoxic T lymphocytes (CTLs) via human leukocyte antigens (HLAs)-restricted pathway. The patho-mechanism involving HLA-restricted presentation of a drug or its metabolites for T-cell activation is supported by the findings of strong genetic associations with HLA alleles (e.g. HLA-B*15:02 and carbamazepine-SJS/TEN, and HLA-B*58:01 and allopurinol-SJS/TEN). However, the genetic associations of SJS/TEN or drug induced cutaneous immune reactions are complex, which are drug specific and ethnicity specific. The genetic polymorphisms and diversity of HLA alleles may provide different binding affinities for drug antigens to launch the activation of specific CTLs responses, further leading to the unique clinical manifestations in SJS/TEN. Fas-FasL and perforin/granzyme B have been advocated mediating the epidermal necrosis in SJS/TEN. Our recent study showed that granulysin, a cytotoxic protein produced by CTLs or natural killer (NK) cells, is the key mediator for disseminated keratinocyte death in SJS/TEN. From the point of view of a physician, the profounder understanding of the genetic predisposition and patho-mechanism we discover, the better strategies for prevention, clinical management, and therapeutic methods of SJS/TEN we can develop in the near future.

Is drug allergy less prevalent than previously assumed? A 5-year analysis

BACKGROUND

Rashes are a frequent conundrum in clinical practice as they may be reactive, drug induced or disease specific. Identification of the culprit drug is important as re-exposure may be harmful or even life-threatening and unnecessary avoidance of 'innocent' drugs leads to limitations of treatment options.

OBJECTIVE

To objectify the cause of suspected cutaneous drug reactions in a large patient population.

METHOD

Over 5years (2006-10), 612 patients with suspected cutaneous drug reactions were evaluated. Histology was assessed. About 200 patients were invited for complete work-up with skin tests (prick/intracutaneous testing and scratch/patch as indicated) and, if necessary, lymphocyte transformation tests (LTT). In special cases, drug provocation tests were conducted.

RESULTS

A total number of 141 cases with suspected drug reaction underwent full work-up (age 6-86years; 75% female, 25% male). In 107 cases (76%) a drug was identified whereas 34 (24%) were reactive rashes or had other causes. Mostly, cutaneous drug reactions were maculopapular rashes, urticaria/angio-oedema; less frequently, acute generalized exanthematous pustulosis, drug reaction with eosinophilia and systemic symptoms, systemic drug-related intertriginous and flexural exanthema, toxic epidermal necrolysis and fixed drug eruptions were present. Of all the cutaneous drug reactions investigated, 39·8% were caused by antibiotics, 21·2% by anti-inflammatories, 7·6% by contrast media and 31·4% by others (oral antidiabetics, antimycotics, antipsychotics, antiepileptics and others).

CONCLUSION

Clinical assessment overestimates the role of drug allergies in cutaneous reactions. Assessment of suspected drug reactions can be greatly improved by thorough evaluation including dermatological and allergological work-up with skin testing and assays such as LTT.

A survey on polypharmacy and use of inappropriate medications

In the past, polypharmacy was referred to the mixing of many drugs in one prescription. Today polypharmacy implies to the prescription of too many medications for an individual patient, with an associated higher risk of adverse drug reactions (ADRs) and interactions. Situations certainly exist where the combination therapy or polytherapy is the used for single disease condition. Polypharmacy is a problem of substantial importance, in terms of both direct medication costs and indirect medication costs resulting from drug-related morbidity. Polypharmacy increases the risk of side effects and interactions. Moreover it is a preventable problem. A retrospective study was carried out at Bhopal district (Capital of Madhya Pradesh, India) in the year of September-November 2009 by collecting prescriptions of consultants at various levels of health care. The tendency of polypharmacy was studied and analyzed under the various heads in the survey. Available data suggests that polypharmacy is a widespread problem, and physician, clinical pharmacists and patients are all responsible. These risks can be minimized through identifying the prevalence of this potential problem in a high-risk population and by increasing awareness among patients and healthcare professionals. Physicians and clinical pharmacists have the potential to combating this problem through a variety of interventions such as reducing the number of medications taken, reducing the number of doses taken, increasing patient adherence, preventing ADRs, improving patient quality of life and decreasing facility and drug costs.

Multiple drug intolerance syndrome: prevalence, clinical characteristics, and management

BACKGROUND

Population-based data on the demographics and clinical characteristics of patients with multiple unrelated drug class intolerances noted in their medical records are lacking.

OBJECTIVES

To provide population-based drug "allergy" incidence rates and prevalence, and to identify individuals with multiple drug intolerance syndrome (MDIS) defined by 3 or more unrelated drug class "allergies," and to provide demographic and clinical information on MDIS cases.

METHODS

Electronic medical record data from 2,375,424 Kaiser Permanente Southern California health plan members who had a health care visit and at least 11 months of health care coverage during 2009 were reviewed. Population-based drug "allergy" incidence rates and prevalence were determined for 23 unrelated medication classes.

RESULTS

On January 1, 2009, 478,283 (20.1%) health plan members had at least one reported "allergy." Individuals with a history of at least 1 "allergy" and females, in general, reported higher population-based new "allergy" incidence rates. Multiple drug intolerance syndrome was present in 49,582 (2.1%). The MDIS cases were significantly older, 62.4 ± 16.1 years; heavier, body mass index 29.3 ± 7.1; and likely to be female, 84.9%, compared with average health plan members. They had high rates of health care utilization, medication usage, and new drug "allergy" incidence. They sought medical attention for common nonmorbid conditions.

CONCLUSIONS

Multiple drug intolerance syndrome is in part iatrogenic. It is associated with overweight elderly women who have high rates of health care and medication usage. Urticarial syndromes only explain a small fraction of MDIS cases. Multiple drug intolerance syndrome is associated with anxiety, but not predominately with immunoglobulin E (IgE)-mediated allergy or life-threatening illness. Multiple drug intolerance syndrome can be managed by medication avoidance and judicious rechallenge.

Vancomycin hypersensitivity diagnosed by lymphocyte blast transformation

A 15-year-old male admitted for Pott's puffy tumor developed recurrent episodes of fever, diffuse morbilliform rash, eosinophilia, and tubulointerstitial nephritis while on multiple antibiotics. Lymphocyte blast transformation (LBT), a method of detecting cellular immune response by measuring levels of interferon-γ (IFN-γ), was used to diagnose vancomycin hypersensitivity and guide antibiotic selection.

Results of drug hypersensitivity evaluations in a large group of children and adults

BACKGROUND

Proven IgE or T-cell mediated drug hypersensitivity reactions (DHRs) seem less common in children compared with adults. However, this has never been proved by data.

OBJECTIVE

To determine and compare proven DHR prevalence in children and adults.

METHODS

Using the DAHD (Drug Allergy and Hypersensitivity Database) cohort, children with proven DHRs were compared with adults. The international EAACI-ENDA recommendations were followed. Patients were divided into four groups: index reaction and test during childhood (C/C), index reaction at childhood and test at adulthood (C/A), index reactions at childhood and adulthood and test at adulthood (CA/A), index reaction and test at adulthood (A/A).

RESULTS

A total of 3275 patients (67.9% female), comprising a total of 4370 patient-episodes, were evaluated (74.5% belonged to the A/A group). Prevalence of positive tests was 15.2% (95%CI, 14.1-16.2) for all tested classes, 10.6% (8.3-13.0) for C/C, 10.6% (7.5-13.6) for C/A, 22.1% (12.8-31.3) for CA/A and 16.5% (15.2-17.8) for A/A. The prevalence was lower in group C/C compared with groups A/A (P < 0.0001) and CA/A (P = 0.003). It was also lower in group C/A compared with the two latter groups (respectively P = 0.003 and P = 0.005). Significant differences were found for maculopapular exanthemas only, and not for urticaria/angiœdema and anaphylaxis. The difference was mainly observed with β-lactams and not for NSAIDs.

CONCLUSION AND CLINICAL RELEVANCE

Suspicions of DHRs are less likely to be confirmed in children.

Clinical characteristics of patients with drug hypersensitivity in Norway: a single-centre study

BACKGROUND

Drug hypersensitivity reactions (DHRs) represent an important public health problem. Knowledge of their clinical characteristics will provide improved diagnostic approaches to this topic.

OBJECTIVES

The aim of the present study was to describe the clinical characteristics of patients with suspected DHRs.

METHODS

The medical records of 206 outpatients with suspected DHRs, who consulted a Norwegian allergy centre from January 2005 to December 2009, were investigated in a retrospective study.

RESULTS

Mean age (range) was 44.3 (11-84) years, and 72% of the patients were women. The most common underlying diseases justifying the use of drugs were infections (49%) and pain-related diseases (23%). Antibiotics (53%), non-steroidal anti-inflammatory drugs (NSAIDs) (32%), paracetamol (15%) and other drugs (46%), used as monotherapy or combinations, were the most often suspected drugs. Cutaneous symptoms were the most frequently reported symptoms (83%). Hospitalisation or prolonged hospitalisation was needed in 38% of the cases, and anaphylaxis was reported in 28% of all the patients. Skin prick tests were performed in 185 patients, of which 14 patients had positive test results. Drug provocation tests (DPTs) were performed in only 86 patients, six of which had positive reactions. DHRs were confirmed in 24 and rejected in 81 patients. Unsettled cases (39%) were mainly due to not performing DPTs.

CONCLUSIONS

Suspected DHRs occur predominantly in women. The most common manifestations are cutaneous symptoms, but life-threatening reactions justifying hospitalisation may occur. Antibiotics and NSAIDs are the two drug families most frequently suspected. DPTs need to be included in diagnostic protocols in order to evaluate suspected DHRs.

Pharmacogenetics: past, present and future

The subject area of pharmacogenetics, also known as pharmacogenomics, has a long history. Research in this area has led to fundamental discoveries, which have helped our understanding of the reasons why individuals differ in the way they handle drugs, and ultimately in the way they respond to drugs, either in terms of efficacy or toxicity. However, not much of this knowledge has been translated into clinical practice, most drug-gene associations that have some evidence of clinical validity have not progressed to clinical settings. Advances in genomics since 2000, including the ready availability of data on the variability of the human genome, have provided us with unprecedented opportunities to understand variability in drug responses, and the opportunity to incorporate this into patient care. This is only likely to occur with a systematic approach that evaluates and overcomes the different translational gaps in taking a biomarker from discovery to clinical practice. In this article, I explore the history of pharmacogenetics, appraise the current state of research in this area, and finish off with suggestions for progressing in the field in the future.

Hypersensitivity to nonsteroidal anti-inflammatory drugs (NSAIDs) - classification, diagnosis and management: review of the EAACI/ENDA(#) and GA2LEN/HANNA*

Nonsteroidal anti-inflammatory drugs (NSAIDs) are responsible for 21-25% of reported adverse drug events which include immunological and nonimmunological hypersensitivity reactions. This study presents up-to-date information on pathomechanisms, clinical spectrum, diagnostic tools and management of hypersensitivity reactions to NSAIDs. Clinically, NSAID hypersensitivity is particularly manifested by bronchial asthma, rhinosinusitis, anaphylaxis or urticaria and variety of late cutaneous and organ-specific reactions. Diagnosis of hypersensitivity to a NSAID includes understanding of the underlying mechanism and is necessary for prevention and management. A stepwise approach to the diagnosis of hypersensitivity to NSAIDs is proposed, including clinical history, in vitro testing and/or provocation test with a culprit or alternative drug depending on the type of the reaction. The diagnostic process should result in providing the patient with written information both on forbidden and on alternative drugs.

Diagnosis of drug hypersensitivity in children and adolescents: discrepancy between physician-based assessment and results of testing

BACKGROUND

Diagnosis of drug hypersensitivity is often based on history alone. But such a vague diagnosis may cause limitations of therapeutic options in the future. To confirm or rule out drug hypersensitivity, skin testing, in vitro studies, and challenge tests are necessary. However, the diagnostic value of this complex and time-consuming allergologic work-up, especially in children, remains controversial.

OBJECTIVE

Aim of this retrospective analysis was to compare the results of diagnostic testing in children and adolescents with drug hypersensitivity diagnosed on clinical grounds, i.e., temporal relationship and observation of symptoms alone.

METHODS

We studied 43 children and adolescents (23 females, 20 males, mean age 13) with a history of immediate or delayed hypersensitivity symptoms in temporal relation to drug treatment using standardized skin testing followed by oral challenges. Patients with suspected penicillin hypersensitivity were further evaluated with in vitro tests.

RESULTS

Drug hypersensitivity was excluded in 40 patients by tolerated oral challenge tests with the incriminated drug. In two patients, positive challenge tests confirmed non-steroidal anti-inflammatory drug hypersensitivity. One patient with amoxicillin-associated exanthema developed positive late skin test reactions to aminopenicillins.

CONCLUSION

In childhood and adolescence, allergologic testing in cases of suspected drug hypersensitivity is of importance both to establish a correct diagnosis and to prevent unjustified withholding of a drug or class of drugs.

Expression of α-defensin 1-3 in T cells from severe cutaneous drug-induced hypersensitivity reactions

BACKGROUND

Cytotoxic T cells seem to be the main effector cells in Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN). However, recent data support a role of the innate immune system in the etiopathology of drug-induced cutaneous reactions. In this study, we analyzed the expression of α-defensins 1-3 in mononuclear cells from patients with SJS/TEN, drug-induced maculopapular exanthema (MPE), and healthy donors.

METHODS

DEFA1A3 gene expression was analyzed by quantitative and end-point RT-PCR. Intracellular flow cytometry, immunofluorescence and immunohistochemistry were carried out to verify α-defensin 1-3 protein expression in mononuclear cells from peripheral blood and skin infiltrates. α-Defensin 1-3 concentration was evaluated in plasma and blister fluid samples by ELISA.

RESULTS

We herein describe DEFA1A3 gene expression in peripheral blood mononuclear cells (PBMCs) from patients with drug-induced cutaneous diseases. Gene expression analysis unveiled transcription in CD4 and CD8 peripheral blood T cells. Protein expression was confirmed by intracellular flow cytometry in mononuclear cells from the patients, including monocytes, NK cells, and T cells from peripheral blood and blister fluid. Further analysis of protein content by flow cytometry revealed higher protein levels in CD56(+) CD3(+) lymphocytes from patients with SJS/TEN when compared to MPE and healthy donors. Immunohistological analysis was used to confirm expression in dermal infiltrates. α-Defensin levels were estimated by ELISA to be 3- to 175-fold higher in blister fluid when compared to simultaneously drawn plasma samples.

CONCLUSION

Upregulation of innate immune molecules such as α-defensins 1-3 in T cells from patients with SJS/TEN may be involved in the etiopathology of these life-threatening diseases induced by medications.

Gender aspects in skin diseases

Gender differences in medicine have been recognized in anatomy, physiology, as well as in epidemiology and manifestations of various diseases. With respect to skin disorders, males are generally more commonly afflicted with infectious diseases while women are more susceptible to psychosomatic problems, pigmentary disorders, certain hair diseases, and particularly autoimmune as well as allergic diseases. Significantly, more female sex-associated dermatoses can be identified than the male sex-associated dermatoses. Dermatoses in the genital area differ between men and women. Gender differences also exist in the occurrence and prognosis of certain skin malignancies. The mechanisms underlying gender differences in skin diseases remain largely unknown. Differences in the skin structure and physiology, effect of sex hormones, ethnic background, sociocultural behaviour and environmental factors may interact to exert the influences. A better understanding of gender differences in human health and diseases will allow the development of novel concepts for prevention, diagnosis and therapy of skin diseases.

Challenge Test Results in Patients With Suspected Penicillin Allergy, but No Specific IgE

Purpose

Patients with a history of allergic reaction to penicillin, but with no detectable specific IgE, are common and pose a dilemma. Challenge tests are considered to be the diagnostic gold standard. The aim of this study was to identify subgroups of patients with very low risk for reactions who could be safely tested using a more rapid and simple procedure.

Methods

A total of 580 consecutively referred adult patients with a history of non-serious cutaneous allergic reactions to penicillin, but with no IgE, were challenged with therapeutic doses of penicillin V (phenoxymethylpenicillin), penicillin G (benzylpenicillin), or both.

Results

Only 14 of 580 patients had a positive challenge test. In 11 of the 14, a reaction to challenge occurred within 2 hours, and none were anaphylactic. The year of the original reaction was known for 555 patients; a positive challenge was seen in only 0.4% of those with an original reaction >15 years before challenge, but in 4.6% of those with a more recent original reaction (P=0.001). Onset of a reaction within the first day of the original exposure was a predictive factor for a positive challenge (P=0.001) in patients challenged within 15 years of the original reaction.

Conclusions

Among suspected penicillin-allergic patients with non-severe skin reactions and no detectable specific IgE, the subgroup of patients who originally reacted more than 15 years previously had very low risk for reacting to a challenge. The risk was higher in patients with a more recent original reaction, especially if the symptoms had occurred within the first day of exposure.

Pharmacogenetics of drug hypersensitivity

Drug hypersensitivity reactions and severe cutaneous adverse drug reactions, such as Stevens-Johnson syndrome and toxic epidermal necrolysis, are examples of serious adverse drug reactions mediated through a combination of metabolic and immunological mechanisms that could traditionally not have been predicted based on the pharmacological characteristics of the drug alone. The discovery of new associations between these syndromes and specific HLA has created the promise that risk for these reactions could be predicted through pharmacogenetic screening, thereby avoiding serious morbidity and mortality associated with these types of drug reactions. Despite this, several hurdles exist in the translation of these associations into pharmacogenetic tests that could be routinely used in the clinical setting. HLA-B*5701 screening to prevent abacavir hypersensitivity syndrome is an example of a test now in widespread routine clinical use in the developed world.

General considerations on rapid desensitization for drug hypersensitivity - a consensus statement

Drug hypersensitivity reactions can occur with most drugs, are unpredictable, may affect any organ or system, and range widely in clinical severity from mild pruritus to anaphylaxis. In most cases, the suspected drug is avoided in the future. However, for certain patients, the particular drug may be essential for optimal therapy. Under these circumstances, desensitization may be performed. Drug desensitization is defined as the induction of a temporary state of tolerance of a compound responsible for a hypersensitivity reaction. It is performed by administering increasing doses of the medication concerned over a short period of time (from several hours to a few days) until the total cumulative therapeutic dose is achieved and tolerated. It is a high-risk procedure used only in patients in whom alternatives are less effective or not available after a positive risk/benefit analysis. Desensitization protocols have been developed and are used in patients with allergic reactions to antibiotics (mainly penicillin), insulins, sulfonamides, chemotherapeutic and biologic agents, and many other drugs. Desensitization is mainly performed in IgE-mediated reactions, but also in reactions where drug-specific IgE have not been demonstrated. Desensitization induces a temporary tolerant state, which can only be maintained by continuous administration of the medication. Thus, for treatments like chemotherapy, which have an average interval of 4 weeks between cycles, the procedure must be repeated for every new course. In this paper, some background information on rapid desensitization procedures is provided. We define the drugs and drug reactions indicated for such procedures, describe the possible mechanism of action, and discuss the indications and contraindications. The data should serve as background information for a database (accessible via the EAACI-homepage) with standardized protocols for rapid desensitization for antibiotics, chemotherapeutic agents, monoclonal antibodies/fusion proteins, and other drugs.

Drug provocation tests to betalactam antibiotics: experience in a paediatric setting

BACKGROUND

Few studies have been performed in children with suspected betalactam allergy. We aimed to assess the role of the drug provocation test (DPT) with betalactams in a paediatric setting and to study the association between allergy to betalactam antibiotics and other allergic diseases.

METHODS

We included all the patients under 15 years old who were consecutively referred to the Immunoallergy Department, Dona Estefânia Hospital, Portugal (January 2002 to April 2008) for a compatible history of allergic reaction to betalactam. All were submitted to a DPT. Children were proposed to perform skin tests (ST) to betalactam antibiotics followed by DPT. If they decline ST, a DPT with the culprit drug was performed.

RESULTS

We studied 161 children, 60% were boys, with a median age of 5 years old at the time of the DPT. Thirty-three patients (20.5%) had an immediate reaction and 33 (20.5%) a non-immediate reaction. The severity of the reported reactions was low in most cases. Skin tests to betalactams were performed in 47 children and were positive in 8. DPT was positive in only one (3.4%) of the patients skin tested and in 11 (13.4%) of those not skin tested. The severity of the DPT reaction was low. Asthma and food allergy were associated with a positive DPT in the later group.

CONCLUSIONS

DPT seems a safe procedure even in the absence of ST in non-severe cases. This could be a practical option in infants and pre-school children, where ST are painful and difficult to perform. Additional caution should be taken in children with asthma and food allergy.

Immunological and genetic aspects of asthma and allergy

Prevalence of allergy and allergic asthma are increasing worldwide. More than half of the US population has a positive skin prick test and approximately 10% are asthmatics. Many studies have been conducted to define immunological pathways underlying allergy and asthma development and to identify the main genetic determinants. In the effort to find missing pieces of the puzzle, new genomic approaches and more standardized ones, such as the candidate gene approach, have been used collectively. This article proposes an overview of the actual knowledge about immunological and genetic aspects of allergy and asthma. Special attention has been drawn to the challenges linked to genetic research in complex traits such as asthma and to the contribution of new genomic approaches.

CD8+ T cells mediate skin allergy to amoxicillin in a mouse model

BACKGROUND

Delayed allergic skin reactions to drugs are common iatrogenic diseases mediated by activation of specific T cells in the skin.

METHODS

To better understand the role of T cells in these diseases, we developed a mouse model of drug allergy induced by skin sensitization to amoxicillin (amox), a penicillin antibiotic frequently involved in delayed drug allergy.

RESULTS

Whereas wild-type mice could not be sensitized to amox, CD4+ T-cell-deficient mice developed an amox-specific allergic skin response, mediated by IFN-gamma-producing CD8+ T cells. Amox-specific CD8+ T cells, induced in lymphoid organs at a high frequency during sensitization, were recruited in the skin upon challenge. CD8+ T cells were effectors of the allergic skin reaction to amox as in vivo treatment with depleting anti-CD8 mAbs abrogated the skin inflammatory reaction and as purified CD8+ T cells could adoptively transfer the allergic response to naive recipients.

CONCLUSION

CD8+ T cells mediate penicillin skin allergy.

Allergic and Non-Allergic Drug Hypersensitivity Reactions in Children

Adverse drug reactions (ADR) are an important medical problem. The aim of this study is to investigate the clinical characteristics of children with ADR and to assess the tolerability of alternative drugs in children (under 16 yrs of age) with a history of ADR. We studied 278 children (132 males and 146 females). Patients were studied by recording personal history and performing in vivo skin testing, in vitro laboratory tests and challenge tests. Patients who had experienced mild adverse reactions underwent challenge tests without any premedication; patients with a clinical history of moderate reactions, received a premedication with sodium cromolyn 30 min before the oral challenge; patients with a clinical history of severe reactions or undergoing parenteral challenges, were given an antihistamine 30 minutes before. A total of 660 adverse events were reported with 126 different drugs involved. Antimicrobial agents were the most involved drugs (51.7%). Non-steroidal anti-inflammatory drugs were involved in 22.7% of episodes. The most reported symptoms were cutaneous. Allergy testing was negative in 272 patients. A diagnosis of drug allergy was reported for 6 patients. A total of 669 challenge tests were performed. 639 were negative at first attempt while 22 were positive. Eight were repeated using a different premedication and resulted negative. Hypersensitivity drug reactions in children are mainly non-allergic. A premedication with sodium cromolyn or with oral H1-antihistamines may be useful in preventing ADR.

Approach to the patient with drug allergy

Clinicians commonly encounter patients who report to have drug allergy. In a large part, such allergy corresponds to adverse drug reactions, which are not immune mediated. The incriminated drug need not always be avoided for further therapy. On the other hand, drug allergy may manifest in many unexpected clinical pictures and thus not be recognized. There is no single standardized diagnostic test to confirm the immune-mediated mechanism and to identify the causative drug. Therefore, immune-mediated drug hypersensitivity reactions and their causative drugs have to be considered by the constellation of exposure, timing, and clinical features, including the pattern of organ manifestation. Prior experience with the drug is also an important feature. An allergologic workup with additional investigation may provide some help. Patients should be informed carefully about their drug allergy, whereby symptoms, drug that elicits reaction, modes of diagnosis of drug allergy, and possibly alternatives should be indicated in their allergy passport.

The complex clinical picture of beta-lactam hypersensitivity: penicillins, cephalosporins, monobactams, carbapenems, and clavams

Beta-lactam antibiotics are the drugs most frequently involved in drug hypersensitivity reactions that are mediated by specific immunologic mechanisms. In addition to benzylpenicillin, several chemical structures belonging to 5 major subgroups can induce reactions. The most relevant structure is that of the amoxicillin molecule. Reactions belong to the 4 major mechanisms described by Coombs and Gell, whereby type IV reactions have recently been further subclassified. The most frequent reactions are type I, which are IgE mediated, and type IV, which are nonimmediate and T-cell dependent. IgE-specific antibodies may recognize the benzylpenicilloyl structure or another part of the molecule, such as the side chain, as antigenic determinants. Depending on specific recognition, subjects can be either cross-reactors or selective responders. A variety of entities exist in T-cell reactions, ranging from mild exanthema to life-threatening, severe reactions, such as Stevens-Johnson syndrome or toxic epidermal necrolysis. Diagnostic tests for IgE-mediated reactions can be done in vivo by testing skin with different penicillin determinants or in vitro by quantitating specific IgE antibodies. For nonimmediate reactions, there are also in vitro and in vivo tests, with variable degrees of sensitivity and specificity. The natural history of IgE-mediated reactions indicates that the count of specific IgE antibodies decreases over time and that results of diagnostic tests can become negative.

Acute symptoms of drug hypersensitivity (urticaria, angioedema, anaphylaxis, anaphylactic shock)

Drug hypersensitivity reactions (HSRs) are the adverse effects of drugs which, when taken at doses generally tolerated by normal subjects, clinically resemble allergy. Immediate-reaction of drug HSRs are those that occur less than 1 hour after the last drug intake, usually in the form of urticaria, angioedema, rhinitis, conjunctivitis, bronchospasm, and anaphylaxis or anaphylactic shock. Acute urticarial and angioedema reactions are common clinical problems frequently encountered by internists and general practitioners. They are not specific to drug allergic reaction, and can be caused by various pathogenic mechanisms. Despite the benign course of urticaria and angioedema, a mucocutaneous swelling of the upper respiratory tract could be life-threatening by itself or a feature of anaphylaxis. This article reviews acute symptoms of drug HSR-related urticaria, angioedema, anaphylaxis, and anaphylactic shock, and how clinicians should approach these problems.

Treatment of osteoporosis: recognizing and managing cutaneous adverse reactions and drug-induced hypersensitivity

Cutaneous adverse reactions are reported for many treatments including antiosteoporotic agents. This position paper includes an algorithm for their recognition. With early recognition and proper management, including immediate and permanent withdrawal of the culprit agent, accompanied by hospitalization, rehydration, and systemic corticosteroids, if necessary, the prognosis is good.

INTRODUCTION

Cutaneous adverse reactions are reported for many therapeutic agents and observed in between 0% and 8% of treated patients depending on the drug. The antiosteoporotic agents are reputed to be safe in terms of cutaneous effects; however, there have been a number of case reports of cutaneous adverse reactions, which merit consideration. This was the subject of a Working Group meeting of the European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis in April 2009, to focus on the impact of cutaneous adverse reactions and drug-induced hypersensitivity in the management of postmenopausal osteoporosis. We prepared this position paper following these discussions, and include an algorithm for their recognition.

METHODS

We reviewed cutaneous adverse reactions observed with antiosteoporotic agents, including information from case reports, regulatory documents, and pharmacovigilance.

RESULTS

The cutaneous adverse reactions range from benign reactions including exanthematous or maculopapular eruption (drug rash), photosensitivity, and urticaria to the severe and potentially life-threatening reactions, angioedema, drug rash with eosinophilia and systemic symptoms (DRESS), Stevens Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN). Review of available evidence shows that cutaneous adverse reactions occur with all commonly used antiosteoporotic agents. Notably, there are reports of SJS and TEN for bisphosphonates, and of DRESS and TEN for strontium ranelate. These severe reactions remain very rare (<1 in 10,000 cases).

CONCLUSION

With early recognition and proper management, including immediate and permanent withdrawal of the culprit agent, accompanied by hospitalization and rehydration and systemic corticosteroids if necessary, the prognosis is good.

Pregnancy complication and outcome in women with history of allergy to medicinal agents

PROBLEM

Pregnancy outcome in women with a previous history of drug allergy and the role of drug allergies in adverse pregnancy outcomes is unclear.

METHOD OF STUDY

A retrospective cohort study comparing pregnancies of women with and without history of drug allergy was conducted. Data were collected from the computerized perinatal database. A multiple logistic regression model, with background elimination, was constructed to control for confounders.

RESULTS

Of 186,443 deliveries, 4.6% (n = 8647) occurred in patients with a history of drug allergy. The following conditions were significantly associated with a history of drug allergy: advanced maternal age, recurrent abortions, fertility treatments, hypertensive disorders, and diabetes mellitus. Using multivariate analysis, with background elimination, history of drug allergy was significantly associated with intrauterine growth restriction (OR = 1.52, CI = 1.3-0.8, P < 0.001) and with preterm delivery (OR = 1.26, CI = 1.14-1.38, P < 0.001).

CONCLUSION

A history of drug allergy is an independent risk factor for intrauterine growth restriction and preterm delivery. Further prospective studies are needed to investigate the nature of this association.

Beta-lactam antibiotic sensitization and its relationship to allergic diseases in tertiary hospital nurses

Purpose

Skin allergies through type 1 and 4 hypersensitivity reactions are the most frequent manifestations of drug allergies. We had previously experienced a case of a nurse with cefotiam-induced contact urticaria syndrome. To aid in preventing the progression of drug-induced allergic disease in nurses, we conducted a survey of tertiary hospital nurses who were likely to have been exposed professionally to antibiotics.

Methods

All 539 staff nurses at a tertiary hospital were asked to respond to a questionnaire regarding antibiotic exposure. Of the 457 nurses (84.8%) who responded, 427 (79.2%) received a physical examination of the hands and 318 (59.0%) received skin prick tests with the β-lactam antibiotics cefotiam, cefoperazone, ceftizoxime, flomoxef, piperacillin and penicillin G.

Results

A positive response to at least one of the antibiotics occurred in 8 (2.6%) of the 311 subjects included in the analysis and stages 1 and 2 contact urticaria syndrome were observed in 38 (8.9%) and 3 (0.7%) of 427 nurses, respectively. The frequencies of a positive antibiotic skin test (6.9 versus 1.3%, χ²=7.15, P=0.018), stage 1 contact urticaria syndrome (14.4 versus 7.4%, χ²=4.33, P=0.038) and drug allergy (15.3 versus 3.6%, χ²=18.28, P=0.000) were higher in subjects with a positive skin allergy history than in those without. Allergic rhinitis (P=0.02, OR=3.86, CI=1.23-12.06), night cough (P=0.04, OR=3.12, CI=1.03-9.41) and food allergy (P=0.00, OR=9.90, CI=3.38-29.98) were significant risk factors for drug allergy.

Conclusions

Antibiotic sensitization and drug allergy occurred more frequently in nurses with a positive skin allergy history. Atopy may be an important risk factor for drug allergy.

Towards an ontological theory of substance intolerance and hypersensitivity

A proper ontological treatment of intolerance--including hypersensitivity--to various substances is critical to patient care and research. However, existing methods and standards for documenting these conditions have flaws that inhibit these goals, especially translational research that bridges the two activities. In response, I outline a realist approach to the ontology of substance intolerance, including hypersensitivity conditions. I defend a view of these conditions as a subtype of disease. Specifically, a substance intolerance is a disease whose pathological process(es) are realized upon exposure to a quantity of substance of a particular type, and this quantity would normally not cause the realization of the pathological process(es). To develop this theory, it was necessary to build pieces of a theory of pathological processes. Overall, however, the framework of the Ontology for General Medical Science (which uses Basic Formal Ontology as its uppermost level) was a more-than-adequate foundation on which to build the theory.

Drug hypersensitivity in students from São Paulo, Brazil

BACKGROUND

Drug hypersensitivity is responsible for substantial mortality and morbidity, and increased health costs. However, epidemiological data on drug hypersensitivity in general or specific populations are scarce.

METHODS

We performed a cross-sectional survey of 1015 university students, using a self-reported questionnaire.

RESULTS

The prevalence of self-reported drug hypersensitivity was 12,11% (123/1015). The most frequently implicated drugs were non-steroidal anti-inflammatory drugs (45,9%) and beta-lactam and sulfonamide antibiotics (25,40%). The majority of the patients reported dermatological manifestations (99), followed by respiratory (40), digestive (23) and other (19). Forty-five patients had an immediate type reaction, and 76,72% (89) had the drug by oral route.

CONCLUSION

The results showed that drug hypersensitivity is highly prevalent in university students, and that nonsteroidal anti-inflammatory drug and antibiotics (beta-lactams and sulfonamide) are the most frequently concerned drugs.

A review of adverse cutaneous drug reactions resulting from the use of interferon and ribavirin

Drug-induced cutaneous eruptions are named among the most common side effects of many medications. Thus, cutaneous drug eruptions are a common cause of morbidity and mortality, especially in hospital settings. The present article reviews different presentations of drug-induced cutaneous eruptions, with a focus on eruptions reported secondary to the use of interferon and ribavirin. Presentations include injection site reactions, psoriasis, eczematous drug reactions, alopecia, sarcoidosis, lupus, fixed drug eruptions, pigmentary changes and lichenoid eruptions. Also reviewed are findings regarding life-threatening systemic drug reactions.

Drug hypersensitivity

Drug hypersensitivity represents an immune-mediated reaction to a drug. Although several drug hypersensitivity reactions are confined to the skin and rather mild, some may be life threatening and also involve further organs such as liver, kidney and bone marrow. The exact pathogenesis of many drug hypersensitivity reactions is still obscure. In this review the concepts on how small molecular drugs can activate the immune system are discussed and the hapten, prohapten and p-i concept are explained. Furthermore, the classification of drug hypersensitivity reactions and some common and severe clinical manifestations of drug-induced T cell mediated reactions are presented.

Approach to the patient with drug allergy

Drug allergies are adverse drug reactions mediated by the specific immune system. Despite characteristic signs (eg, skin rash) that raise awareness for possible drug allergies, they are great imitators of disease and may hide behind unexpected symptoms. No single standardized diagnostic test can confirm the immune-mediated mechanism or identify the causative drug; therefore, immune-mediated drug hypersensitivity reactions and their causative drugs must be recognized by the constellation of exposure, timing, and clinical features including the pattern of organ manifestation. Additional allergologic investigations (skin tests, in vitro tests, provocation tests) may provide help in identifying the possible eliciting drug.

The specificity of tests for anti-beta-lactam IgE antibodies declines progressively with increase of total serum IgE

BACKGROUND

Immediate allergic reactions to beta-lactam antibiotics are mediated by specific IgE antibodies. The Phadia CAP System FEIA is a commercial method for quantification of specific IgE. We wished to determine anti-beta-lactam IgE antibodies in patients without penicillin allergy but with high levels of total IgE.

METHODS

Sera from 41 patients (31 with high total IgE, 10 with low total IgE) were analyzed for IgE antibodies specific to penicilloyl G, penicilloyl V, amoxicilloyl and ampicilloyl using the CAP FEIA((R)) method that was available up to 2006. Seven sera that tested positive were rechecked in a new improved system available after 2006.

RESULTS

In patients without a history of penicillin allergy, the specificities of commercial tests for anti-beta-lactam IgE antibodies were 100%, 60%, 27% and 20% at total IgE levels of 8-263 kU/l, 500-664 kU/l, 1000-2000 kU/l and > 2000 kU/l, respectively. In seven retested sera, only 2 (28%) were still positive for penicillin-specific IgE antibody.

CONCLUSION

Before 2006, tests for anti-beta-lactam IgE antibody in patients with total IgE > 500 kU/l were probably often false positive. Patients who were diagnosed as penicillin allergic before 2006 solely on the basis of a positive CAP FEIA test for specific IgE should be considered for diagnostic reevaluation.

Salicylate intolerance: a masquerader of multiple adverse drug reactions

A female in her early 50s presented with a long-standing history of episodic urticaria and angioedema. She also reported urticarial reactions after ingestion of aspirin, prednisone and multiple antibiotics. These medications were all taken during upper respiratory tract infections. An elimination diet followed by a series of open challenges to food chemicals demonstrated an urticarial eruption following the ingestion of mints, which contain high levels of salicylates. A double-blinded placebo-controlled challenge to salicylate confirmed her sensitivity and explained her reaction to aspirin. The patient informed her treating physician of her copious ingestion of mints during upper respiratory tract infections. Drug hypersensitivity to antibiotics and prednisone was excluded on the basis of negative radioallergosorbent tests (RASTs) and/or absent skin-test responses and/or tolerance to oral challenges. This patient had a salicylate intolerance that caused her episodic urticaria and angioedema, and also masqueraded as a drug allergy due to the concurrent ingestion of mints.

Self-reported antibiotic allergy incidence and prevalence: age and sex effects

BACKGROUND

Data on the prevalence and incidence of adverse reactions to antibiotics in outpatient populations are rare. These events are commonly called "allergy" when noted in the medical record.

OBJECTIVES

Determine the prevalence and incidence of allergy, as recorded in the medical record, to the most commonly used antibiotic classes in a large outpatient population using health care in the United States during 2007.

METHODS

Data for drug allergy and antibiotic use were extracted from the electronic health records of 411,543 patients cared for by Kaiser Permanente in San Diego County who had at least one outpatient visit during 2007. Outpatient antibiotic utilization data was obtained for each year between 1995 and 2007. Penicillins, sulfas, cephalosporins, tetracyclines, macrolides, and quinolones were the classes of antibiotics evaluated.

RESULTS

Antibiotics account for a majority of drug allergy entries. Antibiotic classes with higher historical use have higher allergy prevalence. Female patients use more antibiotics than males, and have higher allergy prevalence rates for all classes of antibiotics. There is a steady increase in antibiotic allergy prevalence with aging for both sexes. Females have higher allergy incidence rates for all classes of antibiotics. Antibiotic allergy incidence in female patients is highest for sulfas, 3.4%, compared with 1%-1.5% for all other classes of antibiotics. Antibiotic allergy incidence in males also is highest for sulfas, 2.2%, compared with 1.1% for penicillins and 0.5%-0.6% for all other classes of antibiotics.

CONCLUSIONS

Female sex, use, and increasing age are the primary factors that account for higher antibiotic allergy prevalence. Antibiotic allergy incidence is highest with sulfa class antibiotics.

Work up of patients with history of beta-lactam hypersensitivity

INTRODUCTION

Beta-lactam antibiotics are the most frequent cause of antibiotic hypersensitivity reactions. The study of all cases of suspected beta-lactam hypersensitivity is highly important, to avoid the use of less efficient or more expensive alternatives, for fear of a reaction.

MATERIALS AND METHODS

Sixty-seven consecutive patients with suspected beta-lactam hypersensitivity reactions were studied. Skin prick tests (SPT), intradermal tests (IDT) and specific IgE determination were performed. In non-immediate reactions, epicutaneous testing was also done. If all were negative, a drug challenge was performed.

RESULTS

Sixty-seven patients (54 female symbol), with a mean age + or - SD of 36.6 + or -19.3 years (4-78 years) were studied. The self-reported antibiotics were amoxicillin and amoxicillin/clavulanic acid in 30 (45%), penicillin in 24 (36%), cephalosporins in 11 (16%) and flucloxacillin in 2 (3%). SPT and IDT were positive in 6 patients (9%) and specific IgE in 11 (16%). Only one patient had both positive specific IgE and skin tests. Of the remaining 51 cases, 33 underwent a drug challenge with the culprit antibiotic, with a positive reaction in 2 (6%). In all positive cases and when a drug challenge with the suspected antibiotic was not indicated, a challenge with an alternative drug was done, all with negative results.

CONCLUSIONS

Of the 67 studied cases with history of beta-lactam hypersensitivity reactions, 18 (27%) were confirmed after testing. A combination of skin testing, specific IgE determination and drug challenge is necessary since none has sufficient sensitivity to be used alone.

Mechanisms of drug-induced allergy

We identified English-language publications on hypersensitivity reactions to xenobiotics through the PubMed database, using the search terms drug and/or xenobiotic, hypersensitivity reaction, mechanism, and immune mediated. We analyzed articles pertaining to the mechanism and the role of T cells. Immune hypersensitivity reactions to drugs are mediated predominantly by IgE antibodies or T cells. The mechanism of IgE-mediated reactions is well investigated, but the mechanisms of T-cell-mediated drug hypersensitivity are not well understood. The literature describes 2 concepts: the hapten/prohapten concept and the concept of pharmacological interactions of drugs with immune receptors. In T-cell-mediated allergic drug reactions, the specificity of the T-cell receptor that is stimulated by the drug may often be directed to a cross-reactive major histocompatibility complex-peptide compound. Thus, previous contact with the causative drug is not obligatory, and an immune mechanism should be considered as the cause of hypersensitivity, even in reactions that occur on primary exposure. Indeed, immune-mediated reactions to xenobiotics in patients without prior exposure to the agent have been described recently for radiocontrast media and neuromuscular blocking agents. Thus, the "allergenic" potential of a drug under development should be evaluated not only by screening its haptenlike characteristics but also by assessing its direct immunostimulatory potential.

Mechanisms of drug-induced allergy

We identified English-language publications on hypersensitivity reactions to xenobiotics through the PubMed database, using the search terms drug and/or xenobiotic, hypersensitivity reaction, mechanism, and immune mediated. We analyzed articles pertaining to the mechanism and the role of T cells. Immune hypersensitivity reactions to drugs are mediated predominantly by IgE antibodies or T cells. The mechanism of IgE-mediated reactions is well investigated, but the mechanisms of T-cell-mediated drug hypersensitivity are not well understood. The literature describes 2 concepts: the hapten/prohapten concept and the concept of pharmacological interactions of drugs with immune receptors. In T-cell-mediated allergic drug reactions, the specificity of the T-cell receptor that is stimulated by the drug may often be directed to a cross-reactive major histocompatibility complex-peptide compound. Thus, previous contact with the causative drug is not obligatory, and an immune mechanism should be considered as the cause of hypersensitivity, even in reactions that occur on primary exposure. Indeed, immune-mediated reactions to xenobiotics in patients without prior exposure to the agent have been described recently for radiocontrast media and neuromuscular blocking agents. Thus, the "allergenic" potential of a drug under development should be evaluated not only by screening its haptenlike characteristics but also by assessing its direct immunostimulatory potential.

Granulysin is a key mediator for disseminated keratinocyte death in Stevens-Johnson syndrome and toxic epidermal necrolysis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are life-threatening adverse drug reactions characterized by massive epidermal necrosis, in which the specific danger signals involved remain unclear. Here we show that blister cells from skin lesions of SJS-TEN primarily consist of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, and both blister fluids and cells were cytotoxic. Gene expression profiling identified granulysin as the most highly expressed cytotoxic molecule, confirmed by quantitative PCR and immunohistochemistry. Granulysin concentrations in the blister fluids were two to four orders of magnitude higher than perforin, granzyme B or soluble Fas ligand concentrations, and depleting granulysin reduced the cytotoxicity. Granulysin in the blister fluids was a 15-kDa secretory form, and injection of it into mouse skin resulted in features mimicking SJS-TEN. Our findings demonstrate that secretory granulysin is a key molecule responsible for the disseminated keratinocyte death in SJS-TEN and highlight a mechanism for CTL- or NK cell--mediated cytotoxicity that does not require direct cellular contact.