Cutaneous allergic drug reactions: update on pathophysiology, diagnostic procedures and differential diagnosic

Drug hypersensitivity reactions: review of the state of the science for prediction and diagnosis

Drug hypersensitivity reactions (DHRs) are a type of adverse drug reaction that can occur with different classes of drugs and affect multiple organ systems and patient populations. DHRs can be classified as allergic or non-allergic based on the cellular mechanisms involved. Whereas nonallergic reactions rely mainly on the innate immune system, allergic reactions involve the generation of an adaptive immune response. Consequently, drug allergies are DHRs for which an immunological mechanism, with antibody and/or T cell, is demonstrated. Despite decades of research, methods to predict the potential for a new chemical entity to cause DHRs or to correctly attribute DHRs to a specific mechanism and a specific molecule are not well-established. This review will focus on allergic reactions induced by systemically administered low-molecular weight drugs with an emphasis on drug- and patient-specific factors that could influence the development of DHRs. Strategies for predicting and diagnosing DHRs, including potential tools based on the current state of the science, will also be discussed.

Cutaneous manifestations of cystic fibrosis

Cystic fibrosis (CF) is caused by a mutation in the Cystic fibrosis transmembrane conductance regulator (CFTR) gene, and features recurrent sinus and pulmonary infections, steatorrhea, and malnutrition. CF is associated with diverse cutaneous manifestations, including transient reactive papulotranslucent acrokeratoderma of the palms, nutrient deficiency dermatoses, and vasculitis. Rarely these are presenting symptoms of CF, prior to pulmonary or gastrointestinal sequelae. Cutaneous drug eruptions are also highly common in patients with CF (PwCF) given frequent antibiotic exposure. Finally, CFTR modulating therapy, which has revolutionized CF management, is associated with cutaneous side effects ranging from acute urticaria to toxic epidermal necrolysis. Recognition of dermatologic clinical manifestations of CF is important to appropriately care for PwCF. Dermatologists may play a significant role in the diagnosis and management of CF and associated skin complications.

Novel insights into molecular and cellular aspects of delayed drug hypersensitivity reactions

INTRODUCTION

Delayed drug hypersensitivity reactions (DDHRs) represent a major health problem. They are unpredictable and can cause life-long disability or even death. The pathophysiology of DDHRs is complicated, multifactorial, and not well understood mainly due to the lack of validated animal models or in vitro systems. The role of the immune system is well demonstrated but its exact pathophysiology still a matter of debate.

AREA COVERED

This review summarizes the current understanding of DDHRs pathophysiology and abridges the available new evidence supporting each hypothesis. A comprehensive literature search for relevant publications was performed using PubMed, Google Scholar, and Medline databases with no date restrictions and focusing on the most recent 10 years.

EXPERT OPINION

Although multiple milestones have been achieved in our understanding of DDHRs pathophysiology as a result of the development of useful experimental models, many questions are yet to be fully answered. A deeper understanding of the mechanistic basis of DDHRs would not only facilitate the development of robust and reliable diagnostic assays for diagnosis, but would also inform therapy by providing specific target(s) for immunomodulation and potentially permit pre-therapeutic risk assessment to pursue the common goal of safe and effective drug therapy.

Photodistributed Stevens-Johnson syndrome and toxic epidermal necrolysis: a systematic review and proposal for a new diagnostic classification

BACKGROUND

Ultraviolet radiation (UVR) exposure is commonly reported as a risk factor for Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). However, minimal evaluation of photo-induced SJS/TEN has been conducted. Thus, this review identifies all cases of SJS/TEN that are linked to an acute exposure of UVR and outlines the unifying characteristics of these cases. Furthermore, the theoretical pathogenesis, differential diagnoses, and proposed diagnostic criteria are defined.

METHODS

PubMed, Google Scholar, and other databases and websites were searched from inception to September 2021 to identify studies that met inclusion criteria. The following keywords were utilized: "Stevens-Johnson syndrome" and "toxic epidermal necrolysis" with "ultraviolet," "photodistributed," "photo-induced," "photosensitivity," and "photo." One reviewer assessed study characteristics, with confirmation by a second. The risk of bias was assessed independently by another.

RESULTS

Thirteen patient cases were identified, all reporting ultraviolet radiation prior to rash onset and an underlying causal drug. Case classifications included 7/13 SJS and 6/13 TEN. All cases described the rash as photodistributed with UVR exposure prior to rash onset (delay of 1-3 days) and a causal drug. 10 cases provided evidence that the photodistributed rash lacked linear demarcation (as in a sunburn) with satellite target-like lesions. No cases described a flu-like prodrome.

DISCUSSION

Mucositis, palmar and plantar rash, a positive Nikolsky sign, and a prolonged disease course can help distinguish from photosensitive reactions, while a negative direct immunofluorescence test is important to distinguish from other photo-induced disorders.

CONCLUSION

Physicians should be aware that UVR may precipitate SJS/TEN in patients taking susceptible drugs. After a 24-h delay from UVR exposure, a non-distinct, photodistributed rash appears with no flu-like prodrome and progresses for at least 48 h to include vesiculobullous eruptions and mucous membrane involvement. Photodistributed SJS/TEN appears to be photo-drug-induced with a unique onset and rash presentation that should be recognized as a distinct diagnosis.

Overview of Side-Effects of Antibacterial Fluoroquinolones: New Drugs versus Old Drugs, a Step Forward in the Safety Profile?

Antibacterial fluoroquinolones (FQs) are frequently used in treating infections. However, the value of FQs is debatable due to their association with severe adverse effects (AEs). The Food and Drug Administration (FDA) issued safety warnings concerning their side-effects in 2008, followed by the European Medicine Agency (EMA) and regulatory authorities from other countries. Severe AEs associated with some FQs have been reported, leading to their withdrawal from the market. New systemic FQs have been recently approved. The FDA and EMA approved delafloxacin. Additionally, lascufloxacin, levonadifloxacin, nemonoxacin, sitafloxacin, and zabofloxacin were approved in their origin countries. The relevant AEs of FQs and their mechanisms of occurrence have been approached. New systemic FQs present potent antibacterial activity against many resistant bacteria (including resistance to FQs). Generally, in clinical studies, the new FQs were well-tolerated with mild or moderate AEs. All the new FQs approved in the origin countries require more clinical studies to meet FDA or EMA requirements. Post-marketing surveillance will confirm or infirm the known safety profile of these new antibacterial drugs. The main AEs of the FQs class were addressed, highlighting the existing data for the recently approved ones. In addition, the general management of AEs when they occur and the rational use and caution of modern FQs were outlined.

Pathophysiology of drug hypersensitivity

Drug hypersensitivity reactions (DHRs) are type B adverse drug reactions (ADRs) traditionally defined as unpredictable, dose independent and not related to the drug pharmacology. DHRs, also called drug allergy if the immune system involvement is confirmed, represent around one-sixth of all ADRs and can cause major clinical problems due to their vague clinical presentation and irregular time course. Understanding the underlying pathophysiology of DHRs is very important for their diagnosis and management. Multiple layers of evidence exist pointing to the involvement of the immune system in DHRs. Recent data have led to a paradigm shift in our understanding of the exact pathophysiology of these reactions. Numerous hypotheses proposing explanation on how a low molecular weight drug molecule can elicit an immune reaction have been proposed. In addition to the classical "hapten" hypothesis, the reactive metabolite hypothesis, the pharmacological interaction with the immune system (p-i) concept, the danger/injury hypothesis and the altered peptide repertoire hypothesis have been proposed. We here introduce the inflammasome activation hypothesis and the cross-reactivity hypothesis as additional models explaining the pathophysiology of DHRs. Available data supporting these hypotheses are briefly summarized and discussed. We also introduced the cross-reactivity model, which may provide a platform to appreciate the potential role played by other factors leading to the activation of the immune system. We believe that although the drug in question could be the trigger of the reaction, the components of the immune system mediating the reaction do not act in isolation but rather are affected by the proinflammatory milieu occurring at the time of the reaction. This review attempts to summarize the available evidence to further illustrate the pathophysiology of DHRs.

How to Recognize and Manage Challenging DRESS Cases: Two Case Reports and A Review of the Literature

Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is an uncommon systemic adverse drug reaction. Furthermore, it is a unique syndrome encompassing various manifestations of fever, facial edema, eosinophilia, atypical lymphocytosis, and organ dysfunction. Since there are no large prospective studies concerning DRESS syndrome, current treatment modalities for DRESS have been mainly determined based on various case reports and expert opinions. Corticosteroids are the mainstay of therapy after the cessation of the culprit drug. Although most cases recover within a couple of months, some may persist and even progress despite 1 mg/kg/day of prednisolone or its equivalent. We herein present two cases of severe DRESS syndrome. Both cases presented with organ dysfunction and remained unresponsive to initial treatment with 1 mg/kg/day of intravenous methylprednisolone. Therefore, plasmapheresis or pulse steroid therapy (250 mg/day methylprednisolone for three days) was used. In the follow-up period, patients' clinical conditions improved dramatically without recurrence. We aimed to share our experience in recognizing and managing severe DRESS cases in this manuscript. Furthermore, we reviewed the literature in comparison with the present cases. In conclusion, plasmapheresis or pulse steroid therapy (250 mg/day of methylprednisolone for three days) can be used to treat difficult DRESS cases where organ failure is about to happen.

Protective effects of corni fructus extract in mice with potassium oxonate-induced hyperuricemia

Corni fructus is consumed as food and herbal medicine in Chinese culture. Studies have revealed that corni fructus exhibits potent antioxidant activity; however, few studies have investigated the ability of corni fructus to lower uric acid concentrations. In this study, the xanthine oxidase (XO) inhibition and uric acid–lowering effect of corni fructus extract (CFE) were evaluated in mice with potassium oxonate–induced hyperuricemia. Hyperuricemia is a chronic disease prevalent worldwide and is associated with high recurrence rates. In addition, drugs used to treat hyperuricemia induce side effects that discourage patient compliance. Hyperuricemia induces metabolic imbalances resulting in accumulative uric acid deposition in the joints and soft tissues. Hyperuricemia not only induces gout but also interrupts hepatic and renal function, thereby trigging severe inflammation and various complications, including obesity, nonalcoholic fatty liver disease, diabetes, and metabolic diseases. In this study, the ethyl acetate fraction (EAF) of CFE resulted in yields of antioxidant photochemical components significantly higher than those of CFEs formed using other substances. The EAF of CFE exhibited high free radical scavenging activity and XO inhibition and effectively lowered uric acid concentrations in the animal model of chemically induced hyperuricemia. The results of this study can serve as a reference for the prevention of preclinical gout as well as for functional food research.

Patch testing versus interferon-gamma release assay in evaluation of drug eruptions

Delayed-onset T-cell-mediated cutaneous adverse drug reactions are an uncommon but potentially serious result of medication exposures. Identification of culprit medications is crucial, but clinical diagnosis is often difficult. Patch tests and interferon-gamma release assays (IFNγ-RA) were previously reported as potentially useful ancillary tests, while rechallenges remain the reference standard test. We compared the number of positive test results with patch testing and IFNγ-RA for drugs implicated as possible causes of cutaneous reactions. Fifty-one patients with a suspected cutaneous drug eruption underwent patch testing and IFNγ-RA for suspected drugs. Participants were followed up at least 9 months after the onset of the rash with results compared with the clinical diagnosis. Forty-two patients presented with morbilliform/eczematous eruptions; five were diagnosed with fixed drug eruption (FDE) and four with erythema multiforme. None had positive patch testing to the drugs tested. A total of 8/51 (15.6%) patients had positive reaction by the IFNγ-RA, and an additional 11 (21.6%) patients had borderline results. Positive or borderline results were more likely in patients with FDE (80%) than morbilliform/eczematous eruptions (30.9%) or erythema multiforme (25%). Our study emphasizes the necessity of additional effective ancillary tests in the evaluation of drug eruptions and supports the use of IFNγ-RA for drug testing as a tool for identifying medications associated with cutaneous drug eruptions.

Hematologic Features of Children and Adolescent Patients with Acute Hypersensitivity Reactions on Drugs and Food

Hematological parameters and blood biochemical markers were measured in 131 children and adolescent patients (70 boys) aged 2 to 17 years with acute hypersensitivity reactions induced by food (59 patients) and medicines (72 patients) in order to establish differences in clinical manifestations and hematological parameters in children with food and drug hypersensitivity and to elaborate the hematological criteria for differentiating the possible pathophysiological mechanisms of various types of hypersensitivity. Both groups of patients had comparable clinical symptoms with a predominance of skin lesions. The significant differences between the groups with drug- and food-induced hypersensitivity reactions were found in their red blood characteristics. In patients with hypersensitive reactions to drugs, significantly lower levels of erythrocytes and hemoglobin were found, while the median values of these parameters did not exceed the limits of reference values. These differences persisted also in the analysis of hemoglobin values, analyzed with accounting for the age and sex of patients. The reduction of hemoglobin was not accompanied by an increase in bilirubin in these patients. Thus, this fact does not support the assumption about the drug-induced hemolysis as a main effect influencing the hematological parameters. Hemogram evaluation performed during 7–10 days after admission demonstrated a higher level of hemoglobin in both groups. The biochemical markers were not significantly distinguished except bilirubin and alkaline phosphatase which were higher in patients with food-induced hypersensitivity.

An inventory of medicinal products causing skin rash: Clinical and regulatory lessons

A variety of medicinal products have been associated with rash and normally this information should be available in the Summary of Product Characteristics (SmPCs). Our study aimed to investigate the frequency of rash as an adverse drug reaction, based on the information provided by SmPCs of 1,048 single active substances (international non-proprietary names) authorized in the United Kingdom. Data on rash frequency was collected from each SmPC using automated searches based on selected keywords. Data analysis was carried out using R, v. 3.4. We found that over 90% of the medicines used orally or by injection may be associated with rash as an adverse event, the most common classes being protein kinase inhibitors, anticancer medicinal products, monoclonal antibodies, biologicals, antivirals and retinoids, with high variations in rash frequency for products within the same class, but also for products with the same active substance. Analysis of SmPCs revealed the need to increase homogeneity in reporting rash frequency, by using Council for International Organizations of Medical Sciences classification, and Medical Dictionary for Regulatory Activities coding in a more standardized manner, and also the need to include more safety endpoints in clinical trials and to use better the safety results for publication and updating the SmPCs.

Association between serum ferritin and the severity of drug eruptions

Background

Early recognition and treatment for severe drug eruption are important in improving clinical outcomes. A few studies have reported laboratory parameters to evaluate the severity of drug eruptions. This study aimed to determine the association between serum ferritin and the severity of drug eruptions.

Methods

We retrospectively reviewed patients diagnosed with drug eruptions in our hospital from 2013 to 2018.

Results

We identified 85 patients (mean age 53.4 years), 20 in the severe cutaneous adverse drug reactions (SCADRs) group and 65 in the non‐SCADRs group. Serum ferritin level was higher in the SCADRs group compared with that in the CADRs group (P<.001). Serum ferritin was positively associated with peripheral white blood cell count, aspartate aminotransferase level, alanine aminotransferase level, blood glucose level, blood creatinine level, and body temperature. Receiver operating characteristic (ROC) analysis revealed a good diagnostic value of ferritin (area under the curve [AUC]:0.87, 95% confidence interval [CI]:0.78‐0.96) with a sensitivity of 80% and a specificity of 87.7% at a cutoff value of 416.15 ng/mL.

Conclusions

Serum ferritin is significantly associated with the severity of CADRs and hence might be potentially used to evaluate the severity of CADRs.

The Presence of HLA-B75, DR13 Homozygosity, or DR14 Additionally Increases the Risk of Allopurinol-Induced Severe Cutaneous Adverse Reactions in HLA-B*58:01 Carriers

BACKGROUND

Although HLA-B*58:01 is a well-known risk factor for the development of allopurinol-induced severe cutaneous adverse reactions (SCARs), most of the HLA-B*58:01 carriers do not suffer from SCARs despite a long-term use of allopurinol. This suggests that there are other risk factors that determine the fate of HLA-B*58:01 carriers.

OBJECTIVE

The aim of this study was to investigate the additional genetic factors that increase the risk of allopurinol-induced SCARs in HLA-B*58:01 carriers.

METHODS

The incidence of allopurinol-induced SCARs was investigated according to coexisting HLA alleles in all subjects with HLA-B*58:01 who took allopurinol between 2003 and 2017. The allopurinol tolerant group was defined as a group who took allopurinol for more than 60 days without developing hypersensitivity and was compared with the allopurinol-induced SCAR group.

RESULTS

Among the retrospective cohort consisting of 367 HLA-B*58:01 carriers treated with allopurinol, 11 (3.0%) were diagnosed with allopurinol-induced SCARs. When HLA-B75, DR13 homozygosity, or DR14 was present, the incidence of SCARs increased up to 22.2% (odds ratio [OR], 19.568; P = .015), 20.0% (OR, 38.458; P = .001), and 10.7% (OR, 19.355; P = .004), respectively. Among the 153 HLA-B*58:01 carriers with chronic renal insufficiency (CRI), the incidence of SCARs doubled to 6.5% and further increased to 40%, 30%, and 37.5% in the presence of HLA-B75, DR13 homozygosity, or DR14, respectively.

CONCLUSIONS

Secondary screening with HLA-B75, DR13 homozygosity, and DR14 in addition to primary screening with HLA-B*58:01 would enable a more accurate prediction of SCAR occurrence, especially in patients with CRI.

Acneiform Rash Caused by an Unlikely Drug: Topiramate

Topiramate is an antiepileptic drug that can also be used for migraine prophylaxis, weight control, and even for methamphetamine dependence; the dosage margin is wide, and the list of side effects is shorter than with other anticonvulsants. We present the case of a 35-year-old man with a disseminated rash of the trunk and extremities after treatment with 25 mg of topiramate daily as a prophylactic migraine treatment. This case report is useful, as this patient was not polymedicated and had a score of 7 on the Naranjo Adverse Drug Reaction Probability Scale. The patient was diagnosed as atypical DRESS syndrome and resolved satisfactorily with symptomatic treatment and topiramate withdrawal; slowly, the lesions regressed. He required no further drugs for the dermatologic condition.