Hypersensitivity reactions to anticoagulant drugs: diagnosis and management options

Heparin-induced DRESS syndrome in a paediatric patient and successful anaesthetic management in cardiovascular bypass surgery: case report

BACKGROUND

Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) Syndrome is a severe adverse drug reaction marked by delayed hypersensitivity reactions causing skin and systemic complications. DRESS diagnosis is challenging due to the variety of clinical presentations and symptom overlap with other conditions. The perioperative period in these patients requires precise pharmacological strategies to prevent complications associated with this syndrome. The treatment of DRESS induced by unfractionated heparin during cardiopulmonary bypass (CPB) surgery presents some challenges that must be considered when selecting an anticoagulant to avoid side effects. In this case, bivalirudin, a direct thrombin inhibitor, is indicated as an alternative to heparin in patients undergoing CPB. However, in contrast to heparin/protamine, there is no direct reversal agent for bivalirudin.

CASE PRESENTATION

We report the case of an 11-year-old male diagnosed with native aortic valve endocarditis and thrombosis in his left lower extremity. During valvular replacement surgery, systemic unfractionated heparin was administered. Postoperatively, the patient developed fever, eosinophilia and pruritic rash. Warm shock and elevated alanine transaminase (ALT) and aspartate transaminase (AST) levels followed, leading to the diagnosis of DRESS syndrome. Treatment with methylprednisolone resulted in complete resolution of symptoms. Seven years later, the patient was readmitted due to insufficient anticoagulation and a thrombus in the prosthetic aortic valve, presenting a recurrent DRESS episode due to the administration of unfractionated heparin, which was later replaced with low-molecular-weight heparin during hospitalization. Treatment with corticosteroids and antihistamines was initiated, resulting in the resolution of this episode. Ultimately, the patient required the Ross procedure. During this intervention the anticoagulation strategy was modified, unfractionated heparin was replaced with bivalirudin during the procedure and fondaparinux was administered during the postoperative period. This resulted in stable transaminases levels and no eosinophilia.

CONCLUSION

The severity of DRESS Syndrome underscores the importance of early recognition, heightened monitoring, and a comprehensive approach tailored to each patient's needs. This particular case highlights the significance of this approach and may have a substantial clinical impact since it provides alternatives to heparin, such as bivalirudin and fondaparinux, in the anticoagulation strategy of CPB for patients who have a hypersensibility reaction to this medication; thus, enhancing clinical outcomes by minimizing risks linked to adverse drug reactions.

Shake it off: A curious case of rigors

Heparin-induced Anaphylactoid reactions are rare systemic reactions to heparin exposure. Although the exact pathogenesis of the reaction is unclear, in vivo platelet activation from inflammation may play a role. The reaction involves anti-platelet factor 4, a common factor also noted to be involved in heparin-induced thrombocytopenia (HIT). Like HIT, prompt identification of the reaction, immediate discontinuation of heparin, and supportive care are the mainstays of treatment to avoid severe and potentially fatal outcomes. Previous cases have described heparin-induced anaphylactoid reactions in the setting of heparin-induced thrombocytopenia. However, we will present a case of an isolated heparin-induced anaphylactoid reaction without HIT.

Allergic and other adverse reactions to drugs used in anesthesia and surgery

The list of drugs patients may be exposed to during the perioperative and postoperative periods is potentially extensive. It includes induction agents, neuromuscular blocking drugs (NMBDs), opioids, antibiotics, sugammadex, colloids, local anesthetics, polypeptides, antifibrinolytic agents, heparin and related anticoagulants, blue dyes, chlorhexidine, and a range of other agents depending on several factors related to individual patients’ clinical condition and progress in the postoperative recovery period. To avoid poor or ultrarapid metabolizers to a particular drug (for example tramadol and codeine) or possible adverse drug reactions (ADRs), some drugs may need to be avoided during or after surgery. This will be the case for patients with a history of anaphylaxis or other adverse events/intolerances to a known drug. Other drugs may be ceased for a period before surgery, e.g., anticoagulants that increase the chance of bleeding; diuretics for patients with acute renal failure; antihypertensives relative to kidney injury after major vascular surgery; and serotonergic drugs that together with some opioids may rarely induce serotonin toxicity. Studies of germline variations shown by genotyping and phenotyping to identify a predisposition of genetic factors to ADRs offer an increasingly important approach to individualize drug therapy. Studies of associations of human leukocyte antigen (HLA) genes with some serious delayed immune-mediated reactions are ongoing and variations of drug-metabolizing cytochrome CYP450 enzymes, P-glycoprotein, and catechol-O -methyltransferase show promise for the assessment of ADRs and non-responses to drugs, particularly opioids and other analgesics. Surveys of ADRs from an increasing number of institutions often cover small numbers of patients, are retrospective in nature, fail to clearly identify culprit drugs, and do not adequately distinguish immune-mediated from non-immune-mediated anaphylactoid reactions. From the many surveys undertaken, the large list of agents identified during and after anesthesia and surgery are examined for their ADR involvement. Drugs are classified into those most often involved, (NMBD and antibiotics); drugs that are becoming more frequently implicated, namely antibiotics (particularly teicoplanin), and blue dyes; those becoming less frequently involved; and drugs more rarely involved in perioperative, and postoperative adverse reactions but still important and necessary to keep in mind for the occasional potential sensitive patient. Clinicians should be aware of the similarities between drug-induced true allergic type I IgE/FcεRI- and pseudoallergic MRGPRX2-mediated ADRs, the clinical features of each, and their distinguishing characteristics. Procedures for identifying MRGPRX2 agonists and diagnosing and distinguishing pseudoallergic from allergic reaction mechanisms are discussed.

Cutaneous hypersensitivity reaction to low molecular weight heparins in pregnancy, cross reactivity and prednisolone treatment: A case report

In pregnant women, low molecular weight heparin is recommended as the preferred agent for venous thromboembolism prophylaxis and treatment. Despite their widespread application, heparin-induced skin lesions are probably under-reported and under-estimated. We present a case report of a primigravida treated with low molecular weight heparin for deep vein thrombosis, who developed a delayed-type hypersensitivity reaction to enoxaparin, tinzaparin and dalteparin. As the patient was pregnant, treatment options were restricted. Tolerance was achieved with dalteparin with adjuvant administration of prednisolone. An attempt to decrease prednisolone dose triggered delayed-type hypersensitivity reaction recurrence that was solved by keeping the initial prednisolone prescription. To the best of our knowledge, there are no described cases using this approach. In cases of delayed-type hypersensitivity reaction to low molecular weight heparin during pregnancy our case suggests that switching low molecular weight heparin and adjuvant administration of prednisolone can be an option.

Warfarin-induced skin necrosis after the use of an anticoagulation reversal agent

Anticoagulant-induced skin necrosis is a rare and potentially life-threatening complication of anticoagulant therapy. The majority of cases of anticoagulant-induced skin necrosis have been attributed to warfarin, known as warfarin-induced skin necrosis (WISN). The use of anticoagulation reversal agents such as Prothrombinex-VF in the development of WISN is not a commonly documented phenomenon. The authors present a case of WISN post-recommencement of warfarin and the use of Prothrombinex-VF.

Gastrodia elata Blume and Zanthoxylum schinifolium Siebold & Zucc Mixed Extract Suppress Platelet Aggregation and Thrombosis

Background and objectives: Blood vessel thrombosis causes blood circulation disorders, leading to various diseases. Currently, various antiplatelet and anticoagulant drugs, such as aspirin, warfarin, heparin, and non-vitamin K antagonist oral anticoagulants (NOACs), are used as the major drugs for the treatment of a wide range of thrombosis. However, these drugs have a side effect of possibly causing internal bleeding due to poor hemostasis when taken for a long period of time. Materials and Methods: Gastrodia elata Blume (GE) and Zanthoxylum schinifolium Siebold & Zucc (ZS) are known to exhibit hemostatic and antiplatelet effects as traditional medicines that have been used for a long time. In this study, we investigated the effect of a mixed extract of GE and ZS (MJGE09) on platelet aggregation and plasma coagulation. Results: We found that MJGE09 inhibited collagen-and ADP-induced platelet aggregation in vitro. In addition, collagen- and ADP-induced platelet aggregation were also inhibited in a dose-dependent manner on the platelets of mice that were orally administered MJGE09 ex vivo. However, compared with aspirin, MJGE09 did not prolong the rat tail vein bleeding time in vivo and did not show a significant effect on the increase in the prothrombin time (PT) and activated partial thromboplastin time (aPTT). Conclusions: These results suggest that MJGE09 can be used as a potential anticoagulant with improved antithrombotic efficacy.

Blood biocompatibility enhancement of biomaterials by heparin immobilization: a review

Blood contacting materials are concerned with biocompatibility including thrombus formation, decrease blood coagulation time, hematology, activation of complement system, platelet aggression. Interestingly, recent research suggests that biocompatibility is increasing by incorporating various materials including heparin using different methods. Basic of heparin including uses and complications was mentioned, in which burst release of heparin is major issue. To minimize the problem of biocompatibility and unpredictable heparin release, present review article potentially reviews the reported work and investigates the various immobilization methods of heparin onto biomaterials, such as polymers, metals, and alloys. Detailed explanation of different immobilization methods through different intermediates, activation, incubation method, plasma treatment, irradiations and other methods are also discussed, in which immobilization through intermediates is the most exploitable method. In addition to biocompatibility, other required properties of biomaterials like mechanical and corrosion resistance properties that increase by attachment of heparin are reviewed and discussed in this article.

Combination strategies for antithrombotic biomaterials: an emerging trend towards hemocompatibility

Surface-induced thrombosis is a frequent, critical issue for blood-contacting medical devices that poses a serious threat to patient safety and device functionality. Antithrombotic material design strategies including the immobilization of anticoagulants, alterations in surface chemistries and morphology, and the release of antithrombotic compounds have made great strides in the field with the ultimate goal of circumventing the need for systemic anticoagulation, but have yet to achieve the same hemocompatibility as the native endothelium. Given that the endothelium achieves this state through the use of many mechanisms of action, there is a rising trend in combining these established design strategies for improved antithrombotic actions. Here, we describe this emerging paradigm, highlighting the apparent advantages of multiple antithrombotic mechanisms of action and discussing the demonstrated potential of this new direction.

Preoperative Long-term Therapeutic Subcutaneous Heparin Administration into Abdomen: Possible Cause for Nonobstructive Microvascular Flap Failure

The anterioabdominal wall is the most common site for low molecular weight heparin administration for anticoagulation, either for prophylactic or for therapeutic indications. Occasionally, this could be associated with damage of the abdominal pannus microvasculature, which could possibly jeopardize the reliability of free abdominal flaps as deep inferior epigastric perforator and muscle sparing transverse rectus abdominis muscle, especially with therapeutic anticoagulation therapy. These flaps are reliant on a highly intricate complex vascular anatomy and perforasomes for their adequate perfusion and survival. The authors report a case of nonobstructive microvascular failure of a free muscle sparing transverse rectus abdominis muscle utilized for soft tissue coverage following resection of a chest wall breast cancer recurrence on a background of portacath-induced deep venous thrombosis of the axillary and subclavian vein whilst on chemotherapy. History of long-term therapeutic low molecular weight heparin administration in the abdomen resulted in microangiopathic densities evident on computerized tomography scan with subsequent flap failure due to possible jeopardization of the flap microvasculature and perfusion. Following exclusion of common local and systemic factors that can cause vascular compromise, a debridement and salvage re-reconstruction procedure utilizing a contralateral free latissimus dorsi flap was performed. Reconstructive surgeons should be cautious when planning to utilize free abdominal-based flaps on the background of long-term therapeutic low molecular weight heparin administration in the abdomen and may possibly explore other alternative options of using non-abdominal free flaps from the reconstructive armamentarium within this unique context.

Diagnosis and management of the drug hypersensitivity reactions in Coronavirus disease 19: An EAACI Position Paper

Coronavirus disease 2019 (COVID-19), a respiratory tract infection caused by a novel human coronavirus, the severe acute respiratory syndrome coronavirus 2, leads to a wide spectrum of clinical manifestations ranging from asymptomatic cases to patients with mild and severe symptoms, with or without pneumonia. Given the huge influence caused by the overwhelming COVID-19 pandemic affecting over three million people worldwide, a wide spectrum of drugs is considered for the treatment in the concept of repurposing and off-label use. There is no knowledge about the diagnosis and clinical management of the drug hypersensitivity reactions that can potentially occur during the disease. This review brings together all the published information about the diagnosis and management of drug hypersensitivity reactions due to current and candidate off-label drugs and highlights relevant recommendations. Furthermore, it gathers all the dermatologic manifestations reported during the disease for guiding the clinicians to establish a better differential diagnosis of drug hypersensitivity reactions in the course of the disease.

Thromboresistance of Polyurethanes Modified with PEO-Silane Amphiphiles

Surface-induced thrombosis is problematic in blood-contacting devices composed of silicones or polyurethanes (PUs). Poly(ethylene oxide)-silane amphiphiles (PEO-SA) are previously shown effective as surface modifying additives (SMAs) in silicones for enhanced thromboresistance. This study investigates PEO-SAs as SMAs in a PU at various concentrations: 5, 10, 25, 50, and 100 µmol g^-1 PU. PEO-SA modified PUs are evaluated for their mechanical properties, water-driven surface restructuring, and adhesion resistance against a human fibrinogen (HF) solution as well as whole human blood. Stability is assessed by monitoring hydrophilicity, water uptake, and mass loss following air- or aqueous-conditioning. PEO-SA modified PUs do not demonstrate plasticization, as evidenced by minimal changes in glass transition temperature, modulus, tensile strength, and percent strain at break. These also show a concentration-dependent increase in hydrophilicity that is sustained following air- and aqueous-conditioning for concentrations ≥25 µmol g^-1 . Additionally, water uptake and mass loss are minimal at all concentrations. Although protein resistance is not enhanced versus an HF solution, PEO-SA modified PUs have significantly reduced protein adsorption and platelet adhesion from human blood at concentrations ≥10 µmol g^-1 . Overall, this study demonstrates the versatility of PEO-SAs as SMAs in PU, which leads to enhanced and sustained hydrophilicity as well as thromboresistance.

IgE allergy diagnostics and other relevant tests in allergy, a World Allergy Organization position paper

Currently, testing for immunoglobulin E (IgE) sensitization is the cornerstone of diagnostic evaluation in suspected allergic conditions. This review provides a thorough and updated critical appraisal of the most frequently used diagnostic tests, both in vivo and in vitro. It discusses skin tests, challenges, and serological and cellular in vitro tests, and provides an overview of indications, advantages and disadvantages of each in conditions such as respiratory, food, venom, drug, and occupational allergy. Skin prick testing remains the first line approach in most instances; the added value of serum specific IgE to whole allergen extracts or components, as well as the role of basophil activation tests, is evaluated. Unproven, non-validated, diagnostic tests are also discussed. Throughout the review, the reader must bear in mind the relevance of differentiating between sensitization and allergy; the latter entails not only allergic sensitization, but also clinically relevant symptoms triggered by the culprit allergen.

Hypersensitivity reactions to low molecular weight heparins: different patterns of cross-reactivity in 3 patients

Low molecular weight heparins (LMWHs) are used for a variety of indications. The most common type of hypersensitivity reactions to LMWHs are delayed-type hypersensitivity reactions (DHR). Immediate-type hypersensitivity reactions (IHR) occur only sporadically. Cross-reactivity of different LMWHs is a common and unpredictable problem. We present 2 cases of patients who developed DHR to nadroparin and enoxaparin, respectively. The third case presents a patient who developed IHR to nadroparin. Skin tests confirmed the hypersensitivity in all cases. In the cases of DHR, a skin test negative LMWH was identified and was tolerated in a challenge test. In the IHR case, cross-reactivity to all tested LMWHs was established. We hypothesize that the degree of cross-reactivity might depend on the type of hypersensitivity reaction with immediate reactions linked to more extensive cross-reactivity than delayed reactions. This is important to consider because, at least in some cases, a safe alternative LMWH can be identified.

[Vitamin K antagonist-induced necrotic leg ulcer, without protein C and S deficiencies]

INTRODUCTION

Patients treated by vitamin K antagonists (VKA) represent 1% of the population in France. We report a case of atypical necrotic leg ulcers induced by VKA.

CASE REPORT

A 84-year-old woman was referred to our dermatology department because of necrotic leg ulcers that developed for the past 5weeks, and appeared spontaneously after the introduction of a VKA, fluindione. The etiological assessment was non contributive, in particular the search for thrombophilic factors. The skin biopsy found an aspect compatible with pyoderma gangrenosum. The outcome was favorable after discontinuing the fluindione and the switch to apixaban. A complete healing was obtained in 5months.

CONCLUSION

We report an original case of necrotic leg ulcers induced by VKA without deficit of protein C or S, with a pyoderma like histology. Reported cases of ulcers induced by VKA are uncommon and the physiopathology is not well known. The involvement of VKA should be evoked in case of necrotic leg ulcer without specific etiology found.

Oral warfarin intake affects skin inflammatory cytokine responses in rats

Warfarin is an anticoagulant used in prevention/prophylaxis of thromboembolism. Besides the effects on coagulation, non-hemorrhagic reactions have also been documented. Although cutaneous reactions were reported in some patients, the impact on skin immunity was not explored. In the present paper, the effect of 30-day oral warfarin intake on skin cytokine responses in rats was analyzed. Increased release of inflammatory cytokines (TNF, IL-1β and IL-10) was noted by skin explants from rats which received warfarin, but without effect on IL-6. No impact on epidermal cell cytokine secretion was seen, except a tendency of an increase of IL-6 response to stimulation with microbial product lipopolysaccharide (LPS). Topical application of contact allergen dinitrochlorobenzene (DNCB) resulted in slight (numerical solely) increase of TNF release by skin explants of warfarin-treated animals, while epidermal cells responded by increased secretion of all four cytokines examined. The data presented provide new information on the potential of oral warfarin to modulate skin innate immune activity.

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.

Unfractionated heparin versus low molecular weight heparins for avoiding heparin-induced thrombocytopenia in postoperative patients

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is an adverse drug reaction presenting as a prothrombotic disorder related to antibody-mediated platelet activation. It is a paradoxical immune reaction resulting in thrombin generation in vivo, which leads to a hypercoagulable state and the potential to initiate venous or arterial thrombosis. A number of factors are thought to influence the incidence of HIT including the type and preparation of heparin (unfractionated heparin (UFH) or low molecular weight heparin (LMWH)) and the heparin-exposed patient population, with the postoperative patient population at higher risk.Although LMWH has largely replaced UFH as a front-line therapy, there is evidence supporting a lack of superiority of LMWH compared with UFH regarding prevention of deep vein thrombosis and pulmonary embolism following surgery, and similar frequencies of bleeding have been described with LMWH and UFH. The decision as to which of these two preparations of heparin to use may thus be influenced by harmful effects such as HIT. We therefore sought to determine the relative impact of UFH and LMWH on HIT in postoperative patients receiving thromboembolism prophylaxis. This is an update of a review first published in 2012.

OBJECTIVES

The objective of this review was to compare the incidence of heparin-induced thrombocytopenia (HIT) and HIT complicated by venous thromboembolism in postoperative patients exposed to unfractionated heparin (UFH) versus low molecular weight heparin (LMWH).

SEARCH METHODS

For this update, the Cochrane Vascular Information Specialist searched the Specialised Register (May 2016), CENTRAL (2016, Issue 4) and trials registries. The authors searched Lilacs (June 2016) and additional trials were sought from reference lists of relevant publications.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in which participants were postoperative patients allocated to receive prophylaxis with UFH or LMWH, in a blinded or unblinded fashion. Studies were excluded if they did not use the accepted definition of HIT. This was defined as a relative reduction in the platelet count of 50% or greater from the postoperative peak (even if the platelet count at its lowest remained greater than 150 x 10⁹/L) occurring within five to 14 days after the surgery, with or without a thrombotic event occurring in this timeframe. Additionally, we required circulating antibodies associated with the syndrome to have been investigated through laboratory assays.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias. Disagreements were resolved by consensus with participation of a third author.

MAIN RESULTS

In this update, we included three trials involving 1398 postoperative participants. Participants were submitted to general surgical procedures, minor and major, and the minimum mean age was 49 years. Pooled analysis showed a significant reduction in the risk of HIT with LMWH compared with UFH (risk ratio (RR) 0.23, 95% confidence interval (CI) 0.07 to 0.73); low-quality evidence. The number needed to treat for an additional beneficial outcome (NNTB) was 59. The risk of HIT was consistently reduced comparing participants undergoing major surgical procedures exposed to LMWH or UFH (RR 0.22, 95% CI 0.06 to 0.75); low-quality evidence. The occurrence of HIT complicated by venous thromboembolism was significantly lower in participants receiving LMWH compared with UFH (RR 0.22, 95% CI 0.06 to 0.84); low-quality evidence. The NNTB was 75. Arterial thrombosis occurred in only one participant who received UFH. There were no amputations or deaths documented. Although limited evidence is available, it appears that HIT induced by both types of heparins is common in people undergoing major surgical procedures (incidence greater than 1% and less than 10%).

AUTHORS' CONCLUSIONS

This updated review demonstrated low-quality evidence of a lower incidence of HIT, and HIT complicated by venous thromboembolism, in postoperative patients undergoing thromboprophylaxis with LMWH compared with UFH. Similarily, the risk of HIT in people undergoing major surgical procedures was lower when treated with LMWH compared to UFH (low-quality evidence). The quality of the evidence was downgraded due to concerns about the risk of bias in the included studies and imprecision of the study results. These findings may support current clinical use of LMWH over UFH as front-line heparin therapy. However, our conclusions are limited and there was an unexpected paucity of RCTs including HIT as an outcome. To address the scarcity of clinically-relevant information on HIT, HIT must be included as a core harmful outcome in future RCTs of heparin.

Eosinophilic Drug Allergy

While peripheral or tissue eosinophilia may certainly characterize drug eruptions, this feature is hardly pathognomonic for a medication-induced etiology. While delayed drug hypersensitivity reactions with prominent eosinophilic recruitment have been typically classified as type IVb reactions, their pathophysiology is now known to be more complex. Eosinophilic drug reactions have a diversity of presentations and may be benign and self-limited to severe and life-threatening. The extent of clinical involvement is also heterogeneous, ranging from isolated peripheral eosinophilia or single organ involvement (most often the skin and lung) to systemic disease affecting multiple organs, classically exemplified by drug-reaction with eosinophilia and systemic symptoms (DRESS). The spectrum of implicated medications in the causation of DRESS is ever expanding, and multiple factors including drug metabolites, specific HLA alleles, herpes viruses, and immune system activation have been implicated in pathogenesis. Due to this complex interplay of various factors, diagnostic workup in terms of skin and laboratory testing has not been validated. Similarly, the lack of controlled trials limits treatment options. This review also describes other localized as well as systemic manifestations of eosinophilic disease induced by various medication classes, including their individual pathophysiology, diagnosis, and management. Given the multitude of clinical patterns associated with eosinophilic drug allergy, the diagnosis can be challenging. Considerable deficits in our knowledge of these presentations remain, but the potential for severe reactions should be borne in mind in order to facilitate diagnosis and institute appropriate management.

Evidence-Based Criteria for the Choice and the Clinical use of the Most Appropriate Lock Solutions for Central Venous Catheters (Excluding Dialysis Catheters): A GAVeCeLT Consensus

Background

The most appropriate lock solution for central venous access devices is still to be defined. GAVeCeLT – the Italian group for venous access devices – has developed a consensus on the evidence-based criteria for the choice and the clinical use of the most appropriate lock solution for central venous catheters (excluding dialysis catheters).

Method

After the constitution of a panel of experts, a systematic collection and review of the literature has been performed, focusing on clinical studies dealing with lock solutions used for prevention of occlusion (heparin, citrate, urokinase, recombinant tissue plasminogen activator [r-TPA], normal saline) or for prevention of infection (citrate, ethanol, taurolidine, ethylene-diamine-tetra-acetic acid [EDTA], vancomycin, linezolid and other antibiotics), in both adults and in pediatric patients. Studies on central lines used for dialysis or pheresis, on peripheral venous lines and on arterial lines were excluded from this analysis. Studies on lock solutions used for treatment of obstruction or infection were not considered. The consensus has been carried out according to the Delphi method.

Results

The panel has concluded that: (a) there is no evidence supporting the heparin lock; (b) the prevention of occlusion is based on the proper flushing and locking technique with normal saline; (c) the most appropriate lock solution for infection prevention should include citrate and/or taurolidine, which have both anti-bacterial and anti-biofilm activity, with negligible undesired effects if compared to antibiotics; (d) the patient populations most likely to benefit from citrate/taurolidine lock are yet to be defined.

Conclusions

The actual value of heparinization for non-dialysis catheters should be reconsidered. Also, the use of lock with substances with anti-bacterial and anti-biofilm activity (such as citrate or taurolidine) should be taken into consideration in selected populations of patients.

Renal unit practitioners' knowledge, attitudes and practice regarding the safety of unfractionated heparin for chronic haemodialysis

Background

Chronic haemodialysis for adult patients with end-stage kidney failure requires a patent extracorporeal circuit, maintained by anticoagulants such as unfractionated heparin (UFH). Incorrect administration of UFH has safety implications for patients.

Objectives

Firstly, to describe renal practitioners’ self-reported knowledge, attitudes and practice (KAP) regarding the safe use of UFH and its effects; secondly, to determine an association between KAP and selected independent variables.

Method

A cross-sectional descriptive survey by self-administered questionnaire and non-probability convenience sampling was conducted in two tertiary hospital dialysis units and five private dialysis units in 2013.

Results

The mean age of 74/77 respondents (96.1%), was 41.1 years. Most (41/77, 53.2%) had 0–5 years of renal experience. The odds of enrolled nurses having poorer knowledge of UFH than registered nurses were 18.7 times higher at a 95% Confidence Interval (CI) (1.9–187.4) and statistically significant (P = 0.013). The odds of delivering poor practice having ≤ five years of experience and no in-service education were 4.6 times higher at a 95% CI (1.4–15.6), than for respondents who had ≥ six years of experience (P = 0.014) and 4.3 times higher (95% CI 1.1–16.5) than for respondents who received in-service education (P = 0.032), the difference reaching statistical significance in both cases.

Conclusion

Results suggest that the category of the professional influences knowledge and, thus, safe use of UFH, and that there is a direct relationship between years of experience and quality of haemodialysis practice and between having in-service education and quality of practice.

Hypersensitivity reactions to modern antiplatelet and anticoagulant drugs

Anticoagulation and antiplatelet drugs are among the most commonly used medical drugs. In addition to the long-established heparins, hirudins, coumarins and antiplatelet drugs such as acetylsalicylic acid, numerous novel and predominantly synthetic pharmacologic agents have come onto the market in recent years. These new agents act at various sites in coagulation and have significantly broadened treatment options. Whilst immunological hypersensitivity reactions are on the whole rare, they have a considerable impact on patient management when they do occur. The present overview discusses the currently known hypersensitivity reactions to anticoagulant and antiplatelet agents, with particular attention to the newer substance classes including P2Y₁₂ inhibitors, glycoprotein IIb/IIIb receptor antagonists, direct factor Xa inhibitors and direct thrombin inhibitors.

Anaphylaxis to drugs

Drug-induced anaphylaxis is a common cause of anaphylaxis and a leading cause of fatal anaphylaxis. Antibiotics, radiocontrast, and nonsteroidal anti-inflammatory drugs are commonly implicated drugs. Vocal cord dysfunction can mimic anaphylaxis and is often overlooked. β-Lactams are a common cause of anaphylaxis; however, skin testing and drug challenge can usually determine tolerability of other classes of β-lactams. Nonionic contrast agents cause anaphylaxis less frequently than ionic contrast, and immunoglobulin E-mediated mechanisms may have a role in some of these reactions. Skin testing with radiocontrast may have a role in evaluating patients with anaphylaxis to nonionic contrast.

Heparin-induced thrombocytopenia: a review of concepts regarding a dangerous adverse drug reaction

Heparin is a natural agent with antithrombotic action, commercially available for therapeutic use as unfractionated heparin and low molecular weight heparin. Heparin-induced thrombocytopenia (HIT) is a serious adverse reaction to heparin that promotes antibody-mediated platelet activation. HIT is defined as a relative reduction in platelet count of 50% (even when the platelet count at its lowest level is above>150 x 10(9)/L) occurring within five to 14 days after initiation of the therapy. Thrombocytopenia is the main feature that directs the clinical suspicion of the reaction and the increased risk of thromboembolic complications is the most important and paradoxical consequence. The diagnosis is a delicate issue, and requires a combination of clinical probability and laboratory tests for the detection of platelet activation induced by HIT antibodies. The absolute risk of HIT has been estimated between 1% and 5% under treatment with unfractionated heparin, and less than 1% with low molecular weight heparin. However, high-quality evidence about the risk of HIT from randomized clinical trials is scarce. In addition, information on the frequency of HIT in developing countries is not widely available. This review aims to provide a better understanding of the key features of this reaction and updated information on its frequency to health professionals and other interested parties. Knowledge, familiarity, and access to therapeutic options for the treatment of this adverse reaction are mandatory to minimize the associated risks, improving patient safety.

Lovenox Induced Tissue Necrosis, a Case Report and Literature Review

Lovenox is a trade name for Enoxaparin. It is a low molecular weight heparin (LMWH) and has other trade names like Clexane and Xaparin. It is an anticoagulant used to prevent and treat venous thromboembolism events (VTE) like deep vein thrombosis or pulmonary embolism, and is given as a subcutaneous injection. General speaking, the most common skin reactions as a result of enoxaparin use are: urticarial, ecchymosis, and even skin necrosis due to vasculitis. These side effects are usually located at the injection site. New studies have pointed out the side effect that could occur a distance from the site of Lovenox injection. In our case extensive skin and subcutaneous tissue necrosis developed at the abdominal wall injection site.

DRESS syndrome induced by acenocoumarol with tolerance to warfarin and dabigatran: a case report

Drug reaction with eosinophlia and systemic symptoms (DRESS) syndrome describes a severe medication-induced adverse reaction, which shows skin, blood and solid-organ features. Up to 50 drugs have been described to cause DRESS. The main responsible drugs are carbamazepine and allopurinol. There are no previous reports associated with acenocoumarol. A 85-year-old white male, who was treated with acenocoumarol for the prevention of venous thromboembolism due to atrial fibrillation, presented 6 weeks later a maculopapular exanthema of the trunk and limbs as well as purple lesions and blisters on distal parts of his legs. Elevated creatinine, glucose, urea, International Normalized Ratio, gamma-glutamyl-transpeptidase (GGT) and eosinophilia levels were observed. Acenocoumarol was removed and enoxaparine, systemic corticosteroids, antihistamines were used as treatment with a favorable clinical evolution: 1 month later, the skin lesions had disappeared and laboratory parameters were normalized. Patch tests with warfarin and dabigatran were carried out. Two simple-blind, placebo-controlled oral challenges with warfarin and dabigatran were performed. Patch tests were negative, and single-blind, placebo-controlled oral challenges with warfarin and dabigatran were achieved without immediate or delayed reactions. We firstly describe a DRESS syndrome induced by acenocoumarol. Patch test was useful to assess alternative therapies. Tolerance to other anticoagulants (warfarin and dabigatran) was demonstrated.

Recurrent intradialytic heparin induced anaphylaxis: workup and management

Heparin has been widely used for intradialytic anticoagulation since the 1940s. Heparin induced anaphylaxis can be life threatening, mandating early recognition and intervention. However, due to its relative rarity many physicians remain unaware. We report the case of a 70-year-old woman requiring dialysis, who developed recurrent anaphylaxis to intradialytic heparin. We describe a systematic approach to confirm the suspected heparin allergy, which must include an evaluation of predisposing factors, the dialysis equipment and concomitant medications. Further workup for safe alternatives employing skin prick and intradermal tests, as well as provocation tests are discussed.

Skin test concentrations for systemically administered drugs -- an ENDA/EAACI Drug Allergy Interest Group position paper

Skin tests are of paramount importance for the evaluation of drug hypersensitivity reactions. Drug skin tests are often not carried out because of lack of concise information on specific test concentrations. The diagnosis of drug allergy is often based on history alone, which is an unreliable indicator of true hypersensitivity.To promote and standardize reproducible skin testing with safe and nonirritant drug concentrations in the clinical practice, the European Network and European Academy of Allergy and Clinical Immunology (EAACI) Interest Group on Drug Allergy has performed a literature search on skin test drug concentration in MEDLINE and EMBASE, reviewed and evaluated the literature in five languages using the GRADE system for quality of evidence and strength of recommendation. Where the literature is poor, we have taken into consideration the collective experience of the group.We recommend drug concentration for skin testing aiming to achieve a specificity of at least 95%. It has been possible to recommend specific drug concentration for betalactam antibiotics, perioperative drugs, heparins, platinum salts and radiocontrast media. For many other drugs, there is insufficient evidence to recommend appropriate drug concentration. There is urgent need for multicentre studies designed to establish and validate drug skin test concentration using standard protocols. For most drugs, sensitivity of skin testing is higher in immediate hypersensitivity compared to nonimmediate hypersensitivity.

Protein-resistant, reductively dissociable polyplexes for in vivo systemic delivery and tumor-targeting of siRNA

Small interfering RNA (siRNA) has been considered as a very attractive therapeutic alternative to chemical drugs; however, the chemical and biological instability and poor delivery efficiency of siRNA limit its success in clinical applications. Here we report a protein-resistant, reductively dissociable siRNA delivery system based on self-assembled polyelectrolyte complexes of dextran-siRNA conjugates linked by disulfide bonds. The prepared polyplexes exhibit excellent dispersion stability in the presence of serum because of the anti-fouling property of dextran exposed onto the complex surface. The enzymatic degradation of siRNA is also effectively suppressed within the complex. Folates are introduced as an active tumor-targeting moiety via the conjugation of folates to the hydroxyl groups of dextran. An in vivo investigation with a xenograft tumor mouse model shows that the folate-decorated dextran-siRNA conjugates are very efficiently targeted to cancer cells and induce sequence-specific gene silencing.

Delayed-type heparin allergy: diagnostic procedures and treatment alternatives-a case series including 15 patients

Delayed-type hypersensitivity reactions (DTHRs) after subcutaneous application of unfractionated heparins or low-molecular-weight heparins are not uncommon. Standard allergological testing usually includes intracutaneous skin tests and patch testing of different heparins, heparinoids, and thrombin inhibitors followed by subcutaneous and/or intravenous challenge with skin test-negative drugs. We present data from a single-center case series of 15 patients with DTHR after low-molecular-weight heparin administration. Intracutaneous testing that can be considered as gold standard identified the suspicious elicitor in 11 (73.4%) of 15 of the patients. Patch testing was positive in 5 (33.4%) of 15 of the patients and was only positive in patients who were also reacting in the intradermal testing. Intravenous challenge with heparin sodium was performed in 10 of 15 patients and was well tolerated in all cases, despite prior positive intracutaneous tests with the same substance. Intracutaneous documentation of DTHR was not an adequate predictor of intravenous challenge.

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.

A case report describing a suspected rivaroxaban hypersensitivity reaction in a surgical patient

WHAT IS KNOWN AND OBJECTIVE

Rivaroxaban is an oral anticoagulant, currently licensed for use as a venous thromboembolism (VTE) prophylaxis, and recommended by the National Institute for Clinical Excellence (NICE) for all patients undergoing elective hip and knee replacement surgery in the UK. We present the first case of a suspected hypersensitivity to rivaroxaban.

CASE SUMMARY

A 57-year-old man with no previous allergies underwent an uncomplicated, elective partial knee replacement, after which he was prescribed a routine 2-week course of rivaroxaban 10 mg. He developed an allergic response requiring readmission for assessment and treatment 7 days post-operatively.

WHAT IS NEW AND CONCLUSION

We believe this to be the first published case of hypersensitivity associated with rivaroxaban. More research is needed to determine this association. At the same time, given the growing range and increasing use of anticoagulants, particular vigilance is required regarding potential side effects so that these may be managed quickly and effectively in the early stages.