Drug Allergy Diagnosis

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.

Drug-induced hypersensitivity reactions in a Lebanese outpatient population: A decade-long retrospective analysis (2012-2021)

Background

Drug hypersensitivity reactions (DHRs) are becoming more common as a result of increasing prevalence and case complexity. Allergists and clinical immunologists worldwide are challenged daily to adequately diagnose and manage these reactions. Data in the literature regarding DHR outpatient consultations are scarce worldwide, limited in the Middle East, and currently unavailable in Lebanon.

Objective

This retrospective study aimed to evaluate the characteristics of all reported DHRs over 10 years in a tertiary-care allergy clinic in Lebanon.

Methods

We conducted a decade-long (2012-21) retrospective analysis of the archived medical records of patients with a history of DHRs. Demographics, clinical history, diagnostic tools, and characteristics of the DHRs were collected and analyzed.

Results

A total of 758 patients experienced DHRs to therapeutic molecules provided for ambulatory care. Our results identified 72 medications. The most frequently implicated drug classes included β-lactam antibiotics (53.8%), followed closely by nonsteroidal anti-inflammatory drugs (48.9%). Of the 758 patients, 32.6% reported DHRs to multiple molecules, and 11.8% reported concomitant DHRs to 1 or several molecules provided in the perioperative setting. Of those, opioids and neuromuscular blocking agents were the 2 most common therapeutic classes. Furthermore, we evaluated the cross-reactivity between molecules of the same class. In neuromuscular blocking agents, rocuronium and cisatracurium were the most commonly cross-reactive, and for opioids, the most common association we recorded was with morphine and pethidine.

Conclusion

Our findings constitute the first step toward a more comprehensive evaluation of the clinical characteristics of DHRs in Lebanon.

Adverse Reactions to Illicit Drugs (Marijuana, Opioids, Cocaine) and Alcohol

Drug allergy has been a research topic within the allergy field for decades. However, many drug reactions presumed to be of allergic nature are not and originate from different mechanisms. Drug-induced reactions can affect numerous organ systems, present with various symptoms, and have more than 1 mechanism of action. In this rostrum article, we want to give an overview of the different allergic and nonallergic reactions that can be expected with the (illicit) use of cannabis, cocaine, opioids, and alcohol. In addition, this article focuses on the different methods available to diagnose allergy related to these 4 drug types and highlight the pitfalls of nonallergic reactions or allergy "mimickers" complicating the diagnosis of true drug allergy. Finally, the impact on current medical practices and future research in support of the allergist in diagnosis and treatment of these medical problems is addressed.

Dermoscopic Aspects of Cutaneous Adverse Drug Reactions

Background

Little is known about the dermoscopic evaluation of cutaneous adverse drug reactions (CADRs).

Objectives

To evaluate the dermoscopic patterns of CADRs and identify those associated with severe cutaneous adverse reactions to drugs (SCARDs).

Patients and Methods

Patients included in this study from May 2015 to April 2016 had presented with CADRs. CADR presentation and classification were based on standard criteria. SCARDs included Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), overlap SJS/TEN, drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP). The dermoscopic features of CADRs were described and compared according to the severity of the reactions.

Results

Sixty-nine patients were included. Sixteen patients (23.2%) presented SCARDs. The main dermoscopic findings in SJS, overlap SJS/TEN and TEN were black dots or necrotic areas (100%). Erosion [respectively, 4/6 (66.7%), 3/3 (100%) and 1/1 (100%)], necrotic borders [respectively, 4/6 (66.7%), 3/3 (100%) and 1/1, (100%)] and epidermal detachment [respectively, 5/6 (83.3%); 2/3 (66.7%) and 1/1 (100%)] were also common among these reactions. Erythema and purpuric dots were the main dermoscopic findings [respectively, 5/6 (83.3%) and 4/6 (66.7%)] in DRESS. In non-severe reactions, the most prevalent structures were erythema and purpura in exanthema [respectively, 31/33 (93.9%) and 24/33 (72.7%)] and erythema and vascular structures in urticarial reactions [respectively, 6/6 (100%) and 3/6 (50%)]. Black dots or necrotic areas, epidermal detachment, necrotic borders and erosion were highly associated with SCARDs (P < 0.001).

Conclusions

Dermoscopy improves clinical recognition of SCARDs.

Immediate-type hypersensitivity reactions due to antituberculosis drugs: a successful readministration protocol

BACKGROUND

Little is known about drug hypersensitivity reactions from antituberculosis drugs.

OBJECTIVE

To determine the frequency, risk factors, and characteristics of immediate-type hypersensitivity reactions from first-line antituberculosis drugs and to evaluate the usefulness of a readministration protocol for culprit drugs in this group of patients.

METHODS

The study population consisted of patients with tuberculosis who were hospitalized and treated in the authors' hospital in 2011. Demographics and disease and treatment characteristics of patients with immediate-type hypersensitivity from antituberculosis drugs were compared with the other patients. Culprit drugs were readministered gradually according to a defined protocol to patients with immediate-type hypersensitivity.

RESULTS

Tree hundred seventy-nine patients were included in the study. Eighteen immediate-type hypersensitivity reactions were detected in 13 patients (3.43%). The only identified risk factor was female sex (odds ratio 4.085). Isoniazid, rifampicin, pyrazinamide, and ethambutol were readministered in 11 patients and rifampicin was readministered in 2 patients, with 6- to 8-step protocols for each drug. Only in 2 patients did allergic reactions with rifampicin develop during the procedure. In these patients, after treatment and complete remission of allergic symptoms, the last tolerated dose was administered and the protocol was completed with the same adjustments.

CONCLUSION

Immediate-type allergic reactions from antituberculosis drugs are not rare and not related to disease or treatment characteristics. The protocols used in this study provide a useful and safe method for readministration of culprit drugs to patients with antituberculosis drug hypersensitivity.