Delayed-type hypersensitivity skin reactions caused by subcutaneous unfractionated and low-molecular-weight heparins: tolerance of a new recombinant hirudin

Medication Associations With Severe Cutaneous Adverse Reactions: A Case/Non-Case Analysis Using the FDA Adverse Event Reporting System

BACKGROUND

Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP) are potentially life-threatening severe cutaneous adverse reactions (SCARs). Although the classical causal agents of SCARs (antibiotics, anticonvulsants, nonsteroidal anti-inflammatory drugs, and allopurinol) are well characterized, there has been little update to this list to account for newly marketed medications.

OBJECTIVE

To provide an updated and stratified list of medications with significant reporting odds ratios (RORs) of SCARs.

METHODS

A case/non-case analysis using the United States FDA Adverse Event Reporting System was performed.

RESULTS

As expected, the prototypical medication classes made up the majority of reported cases of SJS, TEN, AGEP, and DRESS (77%, 64%, 75%, and 72%, respectively). In addition, several infrequently or previously undescribed classes/medications implicated in SCARs were identified to have significant ROR signals, including acetylcysteine, anticoagulants, diuretics, immunotherapies, proton pump inhibitors, antivirals, and antifungals. Among these reported for SJS were acetylcysteine (ROR: 64.38) and fluconazole (ROR: 17.13). For TEN, we identified furosemide (ROR: 26.32), spironolactone (ROR: 14.45), fluconazole (ROR: 30.21), amphotericin B (39.06), and acetylcysteine (ROR: 93.12). For AGEP, we identified acyclovir (ROR: 61.72), valacyclovir (ROR: 30.76), and enoxaparin (ROR: 27.37). For DRESS, we identified vemurafenib (ROR: 17.35), acyclovir (ROR: 30.63), abacavir (ROR: 26.62), raltegravir (ROR: 23.27), and valacyclovir (ROR: 21.77) to have strong reporting odds.

CONCLUSION

Our analysis provides an updated tool for physicians to reference when identifying suspected SCARs and a basis for future studies to investigate atypical medication causality.

Adverse Drug Reactions and Cutaneous Manifestations Associated With Anticoagulation

Anticoagulants are amongst the most commonly prescribed medications worldwide. Although rare, localised and systemic drug reactions have been reported with anticoagulants that can lead to significant morbidity and mortality. Some of the first signs of drug reactions to anticoagulants are cutaneous changes that, when recognised early, can prevent significant complications. Dermatologists should be aware of these changes to make an early and accurate diagnosis. This is particularly important in instances of skin-induced necrosis caused by systemic toxicity to anticoagulants. This review discusses adverse drug reactions to the traditional anticoagulants, warfarin and heparin, and the newer direct oral anticoagulants (DOACs) such as the thrombin inhibitor, dabigatran, and the factor Xa inhibitors, rivaroxaban, apixaban, and edoxaban. In particular, this review provides dermatologists with a framework for early diagnosis and management of patients with drug reactions to anticoagulants and alerts them to potential bleeding complications associated with minor procedures.

Low-Molecular-Weight Heparins as Immunomodulators in Dermatology Practice

Low-molecular-weight heparins (LMWHs) have some effects on cell proliferation and inflammation beyond mere anticoagulation. They have been tried on treatment of a few dermatological disorders such as lichen planus, skin wound healing, recurrent aphtous stomatitis, chronic urticaria, and contact hypersensitivity. LMWHs are generally well-tolerated drugs, rarely can lead to severe reactions. In this article, we will review the novel indications of LMWHs in dermatology practice and common skin reactions associated with their use.

Heparin-induced skin lesions

Heparins are widely used for prophylaxis and treatment of thromboembolic diseases. Besides bleeding complications, heparin-induced skin lesions are the most frequent unwanted adverse effects of subcutaneous heparin treatment. Evidence suggests that these lesions are more common than previously thought. Lesions are most frequently due to either allergic reactions or to possibly life-threatening heparin-induced thrombocytopenia. Early recognition and adequate treatment are highly important, because although both complications initially show a similar clinical picture, their treatment should be fundamentally different. Furthermore, risk factors associated with the patient, drug, and treatment regimen have been identified. We review the clinical range of heparin-induced skin lesions, emphasise evidence and controversies in epidemiology, diagnosis, and differential diagnosis, and discuss the management of patients with these skin lesions.

Adverse effects of heparin

All the adverse effects of heparins are related to their wide variety of biological activities, with bleeding being the most important safety issue, resulting directly from the potency of heparin as an anticoagulant. However, it is hard to define the bleeding risk, since it depends on numerous parameters including the indication, dosage, method, and duration of heparin application, the clinical study design and definition of bleeding as well as patient characteristics and determinants of bleeding such as type of surgery and co-medication. Nonbleeding complications of heparins are caused by binding of heparin molecules to proteins other than antithrombin and to cells, which is generally more pronounced with unfractionated heparin than with low-molecular-weight heparins. Accordingly, heparin-induced thrombocytopenia, the most severe nonbleeding adverse reaction, occurs about 10 times less with low-molecular-weight heparins than with unfractionated heparin. Frequent and therefore important adverse reactions of heparins are skin lesions resulting from delayed-type hypersensitivity reactions. All the other undesirable effects are discussed as well, but they are mostly clinically irrelevant.

Patch testing in non-immediate drug eruptions

The present review addresses the literature regarding the sensitivity and specificity of the various diagnostic methods for evaluating non-immediate (ie, occurring more than 1 hour after drug administration) hypersensitivity reactions associated with β-lactams and other antibiotics, anticonvulsants, heparins, iodinated contrast media, etc. Such reactions include several clinical entities, which range from mild reactions, such as maculopapular rash and delayed-appearing urticaria, to severe ones, such as acute generalized exanthematous pustulosis (AGEP), Stevens-Johnson syndrome, and toxic epidermal necrolysis (TEN). Clinical and laboratory studies indicate that a cell-mediated pathogenic mechanism is often involved in maculopapular rashes. However, this mechanism has also been demonstrated in other non-immediate reactions, such as urticarial and/or angioedematous manifestations, TEN, bullous exanthems, and AGEP. Patch tests, together with delayed-reading intradermal tests, lymphocyte transformation tests, and challenges, are useful tools for evaluating non-immediate drug eruptions. Patch tests can be performed with any form of commercial drugs and are safer than intradermal tests. However, patch tests are less sensitive than intradermal tests, and their sensitivity may vary, depending on the vehicle used.

Acute generalized exanthematous pustulosis from dalteparin

Heparins are widely used for the prophylaxis and treatment of venous thromboembolism. Several types of immunologically mediated reactions to heparins are reported, among them delayed-type hypersensitivity reactions with erythematous, infiltrated itchy plaques at injection sites. We describe a female patient, whose localized reaction from dalteparin was followed by a generalized rash presenting as acute generalized exanthematous pustulosis. Subcutaneous provocation testing showed cross-reactions to enoxaparin, certoparin, reviparin, nadroparin, danaparoid, fondaparinux, but not to pentosan polysulfate. The danaparoid and in a lesser extent the nadroparin patch showed pustules. Within the next day, a generalized rash developed. The upper aspect of her trunk was highly affected and showed discrete pustules. Despite the fact that low molecular-weight heparins are widely prescribed, this is, to our knowledge, the first observation of a pustular drug eruption attributable to this class of substances.

Allergy to heparins and anticoagulants with a similar pharmacological profile: an update

Heparins are widely used as anticoagulants. Immunologically-mediated side effects raise the question as to whether other substances with heparin-like pharmacological effects can be safely applied. Hypersensitivity reactions to heparin consist of heparin-induced immune thrombocytopenia, allergic vasculitis, hypereosinophilia, immediate hypersensitivity as well as delayed-type skin reactions. Hypersensitivity to unfractionated and low-molecular-weight heparins and semisynthetic heparinoids is increasingly common, and the pathogenesis, however, is still not fully understood. Clinically, this phenomenon is of relevance because of its increasing incidence and the resulting therapeutic difficulties that arise because several cross-reactions between unfractionated and low-molecular-weight heparins as well as between various heparins and heparinoids have been observed. In some patients with cross-reactivity between various heparins and semisynthetic heparinoids, recombinant hirudins, may be safe and effective. Combined allergy to recombinant hirudins and heparins, however, has been reported. Therefore, there is an urgent need for therapeutic alternatives.

Cross-reactivity among drugs: clinical problems

Cross-reactivity among drugs is either mediated by immunologic mechanisms or not. The former kind is usually explained by the presence of common antigenic determinants in the cross-reacting drugs. In the case of compounds provoking non-allergic hypersensitivity reactions, cross-reactivity is explained by a common pharmacological characteristic, such as the inhibitory effect of non-steroidal anti-inflammatory drugs on cyclooxygenase-1 and the capability of muscle relaxants or contrast media to release histamine through a non-immunologic mechanism. The main clinical problem deriving from cross-reactivity among drugs is the compelling need to choose a potentially cross-reactive compound and, therefore, to assess cross-reactivity by diagnostic tests. In choosing alternative compounds, skin testing has been used in evaluating IgE-mediated cross-reactivity between penicillins and cephalosporins, as well as among muscle relaxants. In assessing T cell-mediated cross-reactivity among contrast media, corticosteroids, anticonvulsants and heparins, delayed-reading intradermal tests and patch tests, together with lymphocyte transformation tests, can be performed. Because of the limited sensitivity of in vivo and in vitro testing, the most prudent way of establishing the tolerability of a compound of the same group in patients who especially require one is a graded challenge when other allergologic tests are negative.

Eczematous plaques related to unfractionated and low-molecular-weight heparin in pregnancy

The use of low-molecular-weight heparin has been expanded to prevent pregnancy complications such as pregnancy loss, intra-uterine growth restriction and severe early-onset pre-eclampsia in high-risk patients with evidence of acquired or congenital thrombophilia. Therefore, the number of patients with side effects from low-molecular-weight heparin is expected to increase. We describe two women with infiltrating patchy plaques that developed in reaction to low-molecular-weight heparin during pregnancy. In the first patient, a switch to other formulations of heparin and heparinoid failed; the second patient, however, did well when enoxaparin was replaced with dalteparin. This report confirms the risk of skin reactions to enoxaparin and dalteparin, and reports on a skin reaction associated with danaparoid sodium in a pregnant woman.

Anaphylaxis during the perioperative period

Anesthesiologists use a myriad of drugs during the provision of an anesthetic. Many of these drugs have side effects that are dose related, and some lead to severe immune-mediated adverse reactions. Anaphylaxis is the most severe immune-mediated reaction; it generally occurs on reexposure to a specific antigen and requires the release of proinflammatory mediators. Anaphylactoid reactions occur through a direct non-immunoglobulin E-mediated release of mediators from mast cells or from complement activation. Muscle relaxants and latex account for most cases of anaphylaxis during the perioperative period. Symptoms may include all organ systems and present with bronchospasm and cardiovascular collapse in the most severe cases. Management of anaphylaxis includes discontinuation of the presumptive drug (or latex) and anesthetic, aggressive pulmonary and cardiovascular support, and epinephrine. Although a serum tryptase confirms the diagnosis of an anaphylactic reaction, the offending drug can be identified by skin-prick, intradermal testing, or serologic testing. Prevention of recurrences is critical to avoid mortality and morbidity.

Anticoagulant-related skin reactions

Cutaneous reactions have been reported during anticoagulant therapy with coumarin derivatives, unfractionated and low molecular weight heparins, heparinoids, danaparoid and hirudins. Anticoagulant-induced skin reactions vary from local allergic manifestations to skin necrosis. In patients with allergic reactions, diagnosis and crossreactions between anticoagulants can be confirmed by intracutaneous testing. Coumarin- and heparin-induced skin necrosis are rare, but are important side effects due to their high morbidity and occasional mortality. Cutaneous tests are contraindicated in these patients. In the future, anticoagulant strategies may include direct synthetic thrombin inhibitors (argatroban and melagatran/ximelagatran) and the Factor Xa inhibitor, pentasaccharide (fondaparinux).

The use of low-molecular-weight heparin for the management of venous thromboembolism in pregnancy

Thromboembolic disease is a rare, but important, complication of pregnancy that remains a leading non-obstetric cause of maternal death. The prevention and management of venous thromboembolism (VTE) in pregnant women is a complex area of medicine: a balance must be found between protecting the health of the mother and minimizing the risk to the unborn fetus. Until now, unfractionated heparin has been regarded as the drug of choice for the prevention and treatment of VTE during pregnancy. However, because of its significant side effects (osteoporosis and heparin-induced thrombocytopenia), the inconvenient mode of administration and need for monitoring, unfractionated heparin is now being replaced by low-molecular-weight heparin (LMWH). There is a convincing body of clinical evidence from well-designed studies and prospective case series that supports the efficacy and safety of LMWH in pregnant women. There are also encouraging observations on the efficacy of LMWH in the prevention of severe obstetric complications, which are frequently associated with inherited or acquired thrombophilias. The recently-published guidelines of The American College of Chest Physicians (ACCP), summarized in this review, allows the development of higher clinical standards. However, there is concern over the greater cost of LMWH compared with unfractionated heparin and oral anticoagulants, and cost-effectiveness studies are needed.

The use of intravenous recombinant hirudin in the treatment of deep vein thrombosis in a patient with an acute heparin allergy

We report a case in which intravenous heparin, given for the treatment of acute deep vein thrombosis, precipitated an acute allergic reaction, and an alternative anticoagulant, recombinant hirudin, provided rapid and successful therapeutic intervention.

Pharmacology of low molecular weight heparins

Although intravenous heparin has been the treatment of choice for acute VTE disease, LMWHs are gaining wider recognition and support as not only a new option but also as the standard of care. Each LMWH is viewed as a unique drug by regulatory agencies because of their differing physical and pharmacokinetic attributes. LMWHs have high absorption, high bioavailability, and long half-lives enabling once- or twice-daily dosing with predictable dose-response relationships. These factors enable the LMWHs to be used without laboratory monitoring and at home for acute DVT management. Studies continue to show that LMWH preparations are as at least as effective as heparin in a variety of settings, including VTE disease prophylaxis, management of acute VTE disease, unstable angina, and NSTEMI. They are at least as safe as heparin relative to hemorrhagic complications. Heparin-induced thrombocytopenia is less of a problem with LMWHs. Use of LMWHs has resulted in cost benefits in the treatment of acute DVT, unstable angina, and NSTEMI as well as in prophylaxis against venous thromboembolism. Emergency physicians, because of their unique position at the forefront of acute care, will soon regularly use LMWHs.