Diagnosis of drug-induced skin reactions: a future role for computer-aided systems?

Lab-Based Culprit Drug Identification Methods for Cutaneous Drug Eruptions: A Scoping Review

BACKGROUND

Identification of culprit drugs when managing cutaneous drug eruptions is essential. Causality assessment methods (CAMs) have been proposed, including lab-based techniques. However, no consensus guidelines exist.

OBJECTIVES

To identify and map the functionality and feasibility of lab-based CAMs.

METHODS

A scoping review was conducted to identify culprit drug identification methods. Publications on lab-based methods were analyzed. Medline, Embase, and Cochrane Central Register of Controlled Trials databases were searched.

RESULTS

Twenty-five publications met inclusion criteria. Nine lab-based CAMs were studied, including lymphocyte transformation test, cytokine measurement (ELISpot, ELISA, beads array assay), modified IFN-ɣ ELISpot, CellScan, histamine release, granzyme B-ELISpot, intracellular granulysin, lymphocyte toxicity assay, and HLA allele genotyping. Diagnostic accuracy was reported for 8/9 methods. Clinical assessment and operational algorithms were commonly used as validation benchmarks. Lab-based methods were assessed at different phases of a drug eruption including in the acute (18.1%), recovery (27.3%), acute and recovery (27.3%), or an unspecified phase (27.3%). Lymphocyte transformation test (specificity 30% to 100%, sensitivity 27% to 73%) and cytokine measurement (specificity 76% to 100%, sensitivity 20% to 84%) were the most common methods studied.

CONCLUSIONS

Lab-based CAMs can be low-risk, effective, and complementary of clinical methods. High-quality studies are needed to adequately develop and validate these tools for clinical practice.

Toxicologic Pathology in the 21st Century

Toxicology is and will be heavily influenced by advances in many scientific disciplines. For toxicologic pathology, particularly relevant are the increasing array of molecular methods providing deeper insights into toxicity pathways, in vivo imaging techniques visualizing toxicodynamics and more powerful computers anticipated to allow (partly) automated morphological diagnoses. It appears unlikely that, in a foreseeable future, animal studies can be replaced by in silico and in vitro studies or longer term in vivo studies by investigations of biomarkers including toxicogenomics of shorter term studies, though the importance of such approaches will continue to increase. In addition to changes based on scientific progress, the work of toxicopathologists is and will be affected by social and financial factors, among them stagnating budgets, globalization, and outsourcing. The number of toxicopathologists in North America, Europe, and the Far East is not expected to grow. Many toxicopathologists will likely spend less time at the microscope but will be more heavily involved in early research activities, imaging, and as generalists with a broad biological understanding in evaluation and management of toxicity. Toxicologic pathology will remain important and is indispensable for validation of new methods, quality assurance of established methods, and for areas without good alternative methods.

Drug hypersensitivity reactions targeting the skin in dogs and cats

Adverse drug reactions (ADRs) can be dose dependent or idiosyncratic. Most idiosyncratic reactions are believed to be immune-mediated; such drug hypersensitivities and allergies are unpredictable. Cutaneous reactions are the most common presentation of drug allergies. In veterinary medicine it can be difficult to assess the true prevalence of adverse drug reactions, although reports available suggest that they occur quite commonly. There are multiple theories that attempt to explain how drug allergies occur, because the pathogenesis is not yet well understood. These include the (pro)-hapten hypothesis, the Danger Theory, the pi concept, and the viral reactivation theory. Cutaneous drug allergies in veterinary medicine can have a variety of clinical manifestations, ranging from pruritus to often fatal toxic epidermal necrolysis. Diagnosis can be challenging, as the reactions are highly pleomorphic and may be mistaken for other dermatologic diseases. One must rely heavily on history and physical examination to rule out other possibilities. Dechallenge of the drug, histopathology, and other diagnostic tests can help to confirm the diagnosis. New diagnostic tools are beginning to be used, such as antibody or cellular testing, and may be used more in the future. There is much yet to learn about drug allergies, which makes future research vitally important. Treatment of drug allergies involves supportive care, and additional treatments, such as immunosuppressive medications, depend on the manifestation of the disease. Of utmost importance is to avoid the use of the incriminating drug in future treatment of the patient, as subsequent reactions can be worse, and ultimately can prove fatal.