Mechanisms of drug eruptions: Part I

Oral Implications of Polypharmacy in Older Adults

Over the next several decades, rates of aged populations will increase rapidly. These populations are susceptible to multimorbidities and polypharmacy (concurrently, prescribed 5 or more medications). Many medications have side effects that manifest orally. Therefore, it essential to possess current pharmacologic knowledge to diagnose and treat oral implications of commonly prescribed medications. This article details common medication-induced oral lesions and patient assessment of risk factors for polypharmacy and provides a template to integrate medication reconciliation into dental clinical practice.

Oral Implications of Polypharmacy in Older Adults

Over the next several decades, rates of aged populations will increase rapidly. These populations are susceptible to multimorbidities and polypharmacy (concurrently, prescribed 5 or more medications). Many medications have side effects that manifest orally. Therefore, it essential to possess current pharmacologic knowledge to diagnose and treat oral implications of commonly prescribed medications. This article details common medication-induced oral lesions and patient assessment of risk factors for polypharmacy and provides a template to integrate medication reconciliation into dental clinical practice.

Adverse Drug Events in the Oral Cavity

Adverse reactions to medications are common and may have a variety of clinical presentations in the oral cavity. Targeted therapies and new biologic agents have revolutionized the treatment of cancers, autoimmune diseases, and inflammatory and rheumatologic diseases but have also been associated with adverse events in the oral cavity. This review describes the most common clinical presentations of oral mucosal reactions to medications, namely hyposalivation, lichenoid reactions, ulcers, bullous disorders, pigmentation, fibrovascular hyperplasia, reactive keratosis, dysesthesia, osteonecrosis, infection, angioedema, and malignancy.

Adverse drug events in the oral cavity

Adverse reactions to medications are common and may have a variety of clinical presentations in the oral cavity. Targeted therapies and the new biologic agents have revolutionized the treatment of cancers, autoimmune diseases, and inflammatory and rheumatologic diseases but have also been associated with adverse events in the oral cavity. Some examples include osteonecrosis, seen with not only bisphosphonates but also antiangiogenic agents, and the distinctive ulcers caused by mammalian target of rapamycin inhibitors. As newer therapeutic agents are approved, it is likely that more adverse drug events will be encountered. This review describes the most common clinical presentations of oral mucosal reactions to medications, namely, xerostomia, lichenoid reactions, ulcers, bullous disorders, pigmentation, fibrovascular hyperplasia, white lesions, dysesthesia, osteonecrosis, infection, angioedema, and malignancy. Oral health care providers should be familiar with such events, as they will encounter them in their practice.

Toxic epidermal necrolysis (TEN) Lyell's syndrome

Toxic epidermal necrolysis, a unique rapidly developing mucocutaneous reaction pattern, characterized by sheets of erythema, necrosis and bullous detachment of the epidermis, closely resembling that of scalding of the skin and rapidly fatal, was described by Lyell, and is now recognized as toxic epidermal necrolysis (TEN) Lyell's syndrome. The condition is indistinguishable from staphylococcal scalded skin syndrome (SSSS), and generalized fixed drug eruption. Hence, there has always been controversy as regards terminology. It is well conceived that TEN is equivalent to Stevens-Johnson syndrome (SJS), at its greatest severity. TEN, therefore, is a great challenge and warrants instant attention based on a thorough knowledgeable background covering several related facets including the recent advances in pathogenesis and management strategies. The details contained in the following text should prove very useful in the comprehension of a largely intractable entity.

Adverse antibiotic-induced eruptions associated with epstein barr virus infection and showing Kikuchi-Fujimoto disease-like histology

The antibiotic-induced eruption of infectious mononucleosis is a well-known clinical phenomenon. Latent viral infection with herpesviridae (eg, human herpes virus 6 (HHV-6) and Epstein-Barr virus (EBV)) is suspected to play a role in the drug hypersensitivity syndrome. The cutaneous pathologic findings have not been reported in the former, and are infrequently reported in the latter entity. Herein, we describe the biopsy findings of a cefprozil-induced rash in infectious mononucleosis and a minocycline-associated drug hypersensitivity syndrome. Biopsy of these exanthematous eruptions revealed an acute vacuolar interface superficial and deep perivascular and interstitial lymphocytic dermatitis. CD8(+) lymphocytes predominated and were associated with non-neutrophilic nuclear (karyorrhectic) debris and numerous small CD68(+) and CD123(+) monocytes. These aforementioned features have been described in cutaneous lesions of Kikuchi-Fujimoto disease, an entity whose clinicopathologic findings overlap with both infectious mononucleosis and lupus erythematosus. Serologic evidence of active and chronic active EBV infection was found in both patients, respectively. No evidence of EBV or HHV6 was found in the cutaneous lesions. Plasmacytoid monocytes (CD68(+)/CD123(+) cells), which produce type I interferon, are believed to play a role in viral immunity by protecting other cells from viral infections and promoting survival of antigen-activated T cells. Their presence in these two putative examples of viral-drug immune dysregulation could be a clue to pathogenesis and represent a common cellular component of some adverse cutaneous drug eruptions.

Photo-distributed neutrophilic drug eruption and adult respiratory distress syndrome associated with antidepressant therapy

Drug reactions are well-known complications of antidepressant therapy, often related to photosensitization. Herein is reported a singular case of antidepressant (amoxapine and citalopram) and anxiolytic related (perphenazine) photo-distributed neutrophilic dermatosis and adult respiratory distress syndrome (ARDS). The clinicopathologic findings displayed overlapping features with drug-induced Sweet's syndrome, acute generalized exanthematous pustulosis (AGEP), and so-called sterile neutrophilic folliculitis with perifollicular vasculopathy. Of the three medications, only amoxapine has been associated with AGEP. Treatment with high-dose systemic corticosteroids and cessation of drug therapy was followed by rapid resolution of the cutaneous eruption and respiratory distress. The possibility that neutrophil infiltration of the lung and/or accumulation of neutrophils in the skin and blood served as a source for reactive oxygen species, leading to lung injury and subsequent ARDS, is discussed.

Drug-induced urticaria. Recognition and treatment

Urticaria is the second most common cutaneous manifestation of drug allergy. Drug-induced urticaria is seen in 0.16% of medical inpatients and accounts for 9% of chronic urticaria or angioedema seen in dermatology outpatient departments. Occurring within 24 hours of drug ingestion, it is most commonly caused by penicillins, sulfonamides and nonsteroidal anti-inflammatory drugs. Drug-induced urticaria is seen in association with anaphylaxis, angioedema, and serum sickness. Diagnosis requires a detailed history, knowledge of the most likely agents sometimes supplemented with in vitro and skin testing. For mild reactions, avoidance of the causative drug and treatment with antihistamines will suffice. For anaphylactic shock, treatment with epinephrine (adrenaline), corticosteroids and antihistamines is required. Patients should be educated to inform medical staff about previous drug reactions, and to avoid these and cross-reacting drugs if possible. Medical staff need to routinely enquire about allergy and avoid unnecessary prescriptions.

Lichenoid drug eruption to salsalate

Cutaneous lichenoid eruptions can arise as a result of exogenous compound exposures. Pharmaceutical drugs, industrial compounds, and inhaled particles have been implicated as causative agents. To date, there have been no recorded cases of lichenoid drug eruptions (LDEs) caused by clinical use of the nonsteroidal anti-inflammatory drug salsalate. We describe a patient who experienced a lichenoid eruption after the initiation of salsalate for relief of arthritic pain. This eruption emerged after 1 month of therapy with salsalate, persisted for as long as salsalate was administered, and cleared within 3 weeks of discontinuing the medication. LDEs can clinically and histologically resemble idiopathic or classic lichen planus. Integrating drug history, clinical morphology, clinical distribution, and histopathology can aid in the differentiation. As in our patient's case, curative treatment for LDE requires discontinuation of the drug.

Possible induction of systemic lupus erythematosus by zonisamide

An epileptic male to whom zonisamide and ethosuximide had been administered exhibited fever, pericarditis, pleuritis, arthralgia, and elevated titers of antinuclear antibody and anti-DNA-antibody at 5 years, 11 months of age. It was suggested that zonisamide induced the systemic lupus erythematosus symptoms because the antinuclear antibody titers began to rise after zonisamide was administered, and clinical recovery and a decrease in the anti-DNA-antibody levels promptly followed the discontinuation of the drug. The positive lymphocyte transformation test results against zonisamide further supports the etiologic relationship of the male's lupus and the drug. This first case of zonisamide-induced lupus should alert physicians to the possibility of this serious unwanted effect in patients receiving zonisamide.

Drug allergy diagnosis in humans: possibilities and pitfalls

Due to the potential hazards of drug allergies, an early and reliable diagnosis is crucial. The use of in vivo tests is not recent but, because of the hazards of skin testing in patients with a history of anaphylaxis, they had been abandoned for a while. Recent reevaluations have shown that for some drugs, e.g. antibiotics-reliable skin tests can ensure the diagnosis of drug allergy in up to 70% of cases. Many in vitro tests based on well-defined mechanisms, e.g. the basophil degranulation test have been used for the diagnosis of totally unrelated allergic mechanisms. It is almost impossible to interpret their validity as diagnosis tools. Nevertheless, other tests, e.g. the lymphocyte transformation test which have been evaluated in well-conducted recent studies, seem to have a good predictive value. Their use is still restricted to clinical trials or research studies. A reliable clinical approach as well as a detailed examination of the drug intake remains obligatory to diagnose drug allergy. Available in vivo and in vitro tests are sometimes used to confirm the diagnosis. The sensitivity and specificity of these tests is evaluated in clinical studies. Research to improve the existing tests and to develop new diagnostic tools is still of paramount importance.

T cells isolated from positive epicutaneous test reactions to amoxicillin and ceftriaxone are drug specific and cytotoxic

In order to investigate the function of T cells in cutaneous adverse drug reactions, skin-derived T cells were analyzed in two patients with a drug-induced exanthem. Skin biopsy specimens were obtained from positive epicutaneous test reactions to amoxicillin and ceftriaxone. Immunohistochemical analysis revealed that the majority of the cell infiltrate in both biopsy specimens was composed of activated T cells, of which some expressed perforin. By limiting dilution 36 amoxicillin-specific and 10 ceftriaxone-specific T cell clones were raised. All of these T cell clones expressed CD4/T cell receptor alphabeta. Cytokine analysis after antigen stimulation of the seven best proliferating T cell clones (four specific for amoxicillin and three for ceftriaxone) revealed that these cells secrete high amounts of interleukin-5 and mostly lower or no amounts of tumor necrosis factor alpha, interleukin-4, and interferon-gamma. A part of these CD4+ T cell clones were cytotoxic, i.e., two selected ceftriaxone-specific T cell clones killed target cells after antigen stimulation. The amoxicillin-specific T cell clones failed to show drug-specific cytotoxicity, but killed target cells in the presence of concanavalin A, indicating a principal ability to be cytolytic. In correlation with the in situ expression of perforin on T cells, the ceftriaxone-specific T cell clones also expressed perforin in vitro. In conclusion, a substantial part of the T cells in drug-induced epicutaneous test reactions are drug specific and are composed of a heterogeneous cell population. Drug-specific T cells producing interleukin-5 may contribute to eosinophilia, whereas cytotoxic CD4+ T cells may account for tissue damage. These data underline the role of T cells in delayed-type cutaneous adverse drug eruptions and drug-induced epicutaneous test reactions.

Leukocytoclastic vasculitis: is propranolol implicated?

Drugs frequently cause cutaneous adverse reactions. The suspected agent is sometimes difficult to identify, especially in patients receiving multidrug treatment and with underlying illnesses that may contribute to the clinical picture. In our patient, propranolol-induced leukocytoclastic vasculitis was diagnosed by exclusion.

Infiltration of cytotoxic T cells in drug-induced cutaneous eruptions

BACKGROUND

Previous in vitro data indicate that perforin containing drug-specific cytotoxic T cells are involved in cutaneous drug reactions.

OBJECTIVE

The aim of this study was to investigate the in situ expression of perforin and granzyme B together with the nature of the inflammatory infiltrate in acute drug-induced exanthem. Furthermore, expression of interleukin (IL)-12 and interferon (IFN)-gamma, which are known to stimulate cytotoxic T cells, was investigated.

METHODS

Skin biopsy specimens were obtained from 10 patients with a generalized maculopapular exanthem and from nine controls with normal skin. Expression of CD3, CD4, CD8, CD56, CD1a, CD68, CD25, HLA-DR, CD54, perforin, granzyme B, IL-12 and IFNgamma was analysed using immunohistochemistry.

RESULTS

In contrast to the controls, the skin of patients with an exanthem was mainly infiltrated by T cells (CD4 > CD8) and showed a marked enhancement of perforin and granzyme B immunostaining. Double immunostaining revealed that perforin and granzyme B were expressed in both CD4+ and CD8+ cells, which were partly located at the dermoepidermal junction and in the epidermis. In addition, strong immunreactivity for IL-12 and IFNgamma was observed in the mononuclear cells infiltrate, indicating that these cytokines may be important in activation of these cytotoxic T cells.

CONCLUSION

The increased numbers of perforin and granzyme B containing T cells infiltrating the dermoepidermal junction may contribute to the damage of epidermal cells, which is frequently observed as a typical feature of interface dermatitis in drug-induced exanthem. Our data provide further evidence that cytotoxic T cells play an essential role in cutaneous drug reactions.

The use of skin testing in the investigation of cutaneous adverse drug reactions

Skin testing with the suspected compound has been reported to be helpful in determining the cause of cutaneous adverse drug reactions (ADRs), but the value and specificity of these tests need to be determined. In this study, 72 patients with presumed drug eruptions (27 maculopapular, 18 urticarial, seven erythrodermic, nine eczematous, four photosensitivity, three fixed drug eruptions, three with pruritus and one with acute generalized exanthematous pustulosis) were assessed. All had drug patch tests; 46 also had prick tests and 30 had intradermal tests (performed on hospitalized patients using a sterile solution of the suspected drug, diluted sequentially) with immediate and delayed readings. Among these patients, 52 (72%) had a positive skin test reaction, 43%, 24% and 67% in patch, prick and intradermal skin tests, respectively. The results of skin tests varied with the drug tested and with the clinical type of cutaneous ADR, as a significantly higher number of positive patch tests was observed in maculopapular rashes than in urticarial reactions (P = 0.001). This study supports the value of careful sequential drug skin testing in establishing the cause of cutaneous ADR. Guidelines are proposed for performing these tests, and these include the use of appropriate negative control patients to avoid false-positive results.

Mechanisms of drug reactions: the metabolic track

Hypersensitivity syndrome (HSR) describes a drug-induced symptom complex consisting of fever, rash, and internal organ involvement. Although these reactions are rare, they are very important because of their severity and unpredictability. The metabolic conversion of drugs to chemically-reactive products is now established as a prerequisite for many idiosyncratic drug reactions. In the setting of HSR, an imbalance in the rates of formation of reactive metabolites and of enzymatic detoxification can lead to accumulation of these byproducts. Reactive metabolites could act as haptens eliciting an immune response, covalently bind target proteins causing cell death, or interact with nucleic acids leading to mutations. The lymphocyte toxicity assay (LTA) provides an in vitro assessment of host susceptibility to reactive metabolites of a given drug. It has validated the clinical finding of increased risk of HSR in first degree relatives of patients. It is hoped that the LTA will be used to predict host susceptibility before drug exposure. Ultimately it is hoped that the genetic defects that lead to drug reactions will be identified. This would improve drug development safety and allow primary prevention of serious reactions.