Delayed-type hypersensitivity to subcutaneous enoxaparin

Postoperative fever secondary to enoxaparin usage with pork allergy

Postoperative fevers are common in hospitalised patients and warrant workup beyond the early post-op period. A 50-year-old man was admitted after sustaining a tibial plateau fracture. Fevers began 3 days after external fixation and persisted through a second surgery despite initial negative workup. Careful review of medications revealed enoxaparin as the instigating agent of a febrile drug reaction, and the fevers resolved after discontinuing the drug. On further questioning, it was discovered the patient had an allergy to pork, from which the main components of enoxaparin are typically derived. To our knowledge, this is the first reported enoxaparin-induced fever in the setting of a pork allergy. Enoxaparin-induced fevers should be considered in patients with unexplained post-op fever. Our case demonstrates the importance of analysing newly administered medications. Simple detailed history may significantly reduce patient morbidity and help to broaden differentials during investigation.

Thromboembolism prophylaxis with dabigatran leads to lower perioperative blood loss than with dalteparin in primary knee arthroplasty

INTRODUCTION

Low-molecular-weight heparins (LMWH) are commonly used in thrombosis prophylaxis after total knee arthroplasty. In contrast to LMWH, dabigatran etexilate is an oral and direct acting anticoagulant. The hypothesis of the present study was that blood loss occurring in total knee arthroplasty (TKA) is not greater after dabigatran etexilate than after dalteparin.

METHOD

All patients suffering from primary arthrosis of knee joint that had received a total knee arthroplasty were included in this retrospective case-control study. Two groups were formed (dalteparin versus dabigatran etexilate) and the perioperative blood loss was compared using the formula of Nadler (V = EBV × ln (Hct(0)/Hct(1)) [V = blood loss (l); EBV = blood volume (l); Hct(0) = preoperative haematocrit; Hct(1) = haematocrit on the first postoperative day].

PATIENTS

A total of 155 patients, 61 men and 94 women, were included. The calculated blood loss differed significantly between the two groups. The blood loss was on average 1.5 ± 0.58 l [0.32-2.9 l] in the dalteparin group, compared with 1.3 ± 0.63 l [0.29-4.31 l] in the dabigatran etexilate group (p < 0.01). None of the patients of both observed groups showed clinical signs of thrombosis or pulmonary artery embolism.

RESULTS

Dabigatran etexilate showed a lower perioperative blood loss than dalteparin by comparable safety of both drugs.

CONCLUSION

Whether the timing of administration or pharmacological factors were responsible for this cannot be explained by our study.

The complex clinical picture of side effects to anticoagulation

Inflammatory plaques at injection sites are frequent side effects of heparin treatment and a clinical symptom of delayed-type hypersensitivity (DTH) to heparin. In most cases, changing the subcutaneous therapy from unfractionated to low-molecular-weight heparin or treatment with heparinoids does not provide improvement because of extensive cross-reactivity. Because of their completely different chemical structure, hirudins are a safe alternative for anticoagulation. Despite DTH to subcutaneously injected heparins, patients tolerate heparin intravenously. Therefore, in case of therapeutic necessity and DTH to heparins, the simple shift from subcutaneous to intravenous heparin administration is justified. Skin necrosis is a rare complication of anticoagulation. Heparin-induced skin necrosis is 1 of the symptoms of immune-mediated heparin-induced thrombocytopenia and should result in the immediate cessation of heparin therapy to prevent potentially fatal thrombotic events. This is in contrast to coumarin-induced skin necrosis, where therapy may be continued or restarted at a lower dose.

Extensive exfoliative dermatitis induced by non-ionic contrast medium Iodixanol (Visipaque®) used during percutaneous coronary intervention

We report a case of extensive exfoliative dermatitis in a patient appearing 3 days after intracoronary administration of non-ionic contrast medium Iodixanol (Visipaque) during the primary percutaneous coronary intervention. The patient presented with acute myocardial infarction and has never exposed to any X-ray contrast medium. The patient was successfully treated with corticosteroid, antihistamines and antibiotics for the prevention of secondary bacterial infection. The patient was recovered 8 days after the anti-allergic medical management. This case can be a rare example of late-onset allergic reaction to a non-ionic contrast medium Iodixanol presented with extensive exfoliative dermatitis.

Delayed-type hypersensitivity to low molecular weight heparins and heparinoids: cross-reactivity does not depend on molecular weight

BACKGROUND

Cross-reactivity is a widespread phenomenon in patients who develop cutaneous delayed-type hypersensitivity (DTH) reactions to low molecular weight heparins (LMWHs). As molecular weight is believed to be a key determinant of sensitization to heparins, the recently developed LMWH bemiparin, with the lowest molecular weight of all LMWHs, appeared to be a significant improvement.

OBJECTIVES

To evaluate cross-reactivity between bemiparin and several other LMWHs and heparinoids by means of subcutaneous testing. Methods Test doses of bemiparin and several other LMWHs/heparinoids were given to eight patients with a history of local eczematous reactions after subcutaneous injection of enoxaparin.

RESULTS

Seven of eight patients showed cross-reactivity following subcutaneous injection of bemiparin. In addition, nearly all tested substances caused local eczematous reactions in at least some patients, with the exception of fondaparinux, which was well tolerated by all patients. Of all substances tested, bemiparin had the highest cross-reactivity with enoxaparin. Substances with a lower molecular weight did not cross-react less frequently than the others.

CONCLUSIONS

No significant correlation was found between the molecular weight of the tested substances and the frequency of DTH reactions. In patients with DTH to enoxaparin, the LMWH bemiparin is not a suitable alternative.

Tolerance to intravenous heparin in patients with delayed-type hypersensitivity to heparins: a prospective study

Delayed-type hypersensitivity to subcutaneously injected heparin is relatively common. Particularly, extensive cross-reactivity between different heparins and heparinoids often occurs. Delayed-type hypersensitivity to heparin implies the risk of a generalized eczema when heparin is administered intravenously. However, case reports demonstrated a tolerance to intravenous heparin in patients with delayed-type hypersensitivity to subcutaneous heparin, but prospective studies have not been performed. Our study group, of 28 patients with a proven delayed-type hypersensitivity to subcutaneous heparin, was challenged with intravenous heparin, which was well tolerated in all 28 patients. Therefore, in case of therapeutic necessity, the shift from subcutaneous to intravenous heparin administration is justified.

Allergy to heparin: a new in vitro diagnostic technique

INTRODUCTION

Few descriptions of allergic reactions to heparin have been published, because these reactions are not well known, their prevalence is low and they are difficult to diagnose due to the lack of an in vitro test until now. We propose a new technique, the basophil activation test (BAT) for the diagnosis of these reactions.

METHODS AND RESULTS

We performed in vivo and in vitro studies with heparin and its derivatives in two patients with heparin-induced acute urticaria. In both patients the results of prick tests with sodium and calcium heparin, enoxaparin and nadroparin with immediate reading were negative. Intradermal skin tests with immediate reading and reading at 48 and at 96 hours with calcium heparin, enoxaparin and nadroparin were positive in the immediate reading and after 48 hours in the first patient. The second patient showed positivity to nadroparin in the immediate reading. The same drugs were also tested using patch tests, with reading after 48 and 72 hours. The second patient showed positivity to nadroparin after 48 hours. The BAT was positive to enoxaparin in the first patient and revealed showed slight positivity to sodium heparin in the second patient.

CONCLUSIONS

We consider the BAT to be a useful, safe and reliable test for the in vitro diagnosis of heparin allergy. This test avoids the use of provocation tests, which present a risk to the patient.

Delayed cutaneous reactions to heparin in antiphospholipid syndrome during pregnancy

BACKGROUND

Clinical symptoms related to antiphospholipid antibodies often first occur during pregnancy with the diagnosis of antiphospholipid syndrome (APS). Unfractionated heparin (UFH) and low-dose aspirin are considered as first-line treatments for pregnant women with APS and recurrent fetal loss. However, in addition to an increased incidence of hemorrhagic side-effects and thrombocytopenia there are a number of drug eruptions with cutaneous components secondary to the use of UFH. One of these eruptions has been classified as a delayed type I.V. hypersensitivity reactions at the sites of UFH injections. The majority of these reactions occur in pregnant women.

METHOD

We present three pregnant patients who developed delayed hypersensitivity reactions at the sites of UFH injections. Two patients had documented APS and the other patient had two previous spontaneous abortions.

RESULTS

The histopathologic and immunohistochemical findings in the biopsy specimens from the sites of the delayed reactions were distinctive. The inflammatory infiltrate contained CD3+ and CD4+ lymphoid cells with plasma cells, and eosinophils. There was a marked increased in mast cells with increased stromal cells within the dermis and increased vascular proliferation.

CONCLUSIONS

The distinctive histopathologic and immunohistochemical features seen in the delayed hypersensitivity reactions at the sites of UFH injections may be modulated by the immunomodulatory effects of UFH as well as the hormonal levels and cytokine patterns during pregnancy. Alternative therapies may not always be successful in resolving the reactions.

Adverse dermatologic effects of cardiovascular drug therapy: part III

Cardiovascular disease is common, affecting an increasing number of persons as the population ages. To combat this growing health problem, physicians use a multitude of medications in the treatment of their patients. Although pharmacologic therapy greatly enhances quality of life for a majority of patients, there is always the potential for an unfavorable reaction. For example, cardiovascular drugs can induce a vast array of adverse dermatologic responses. This article reviews the various cutaneous reaction patterns that can occur as a result of treatment with vasodilators and other antihypertensive drugs, anticoagulants and antiplatelet drugs, thrombolytic agents, and lipid-lowering agents.

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.

Rupture of a previously normal spleen in association with enoxaparin: An unusual cause of shock

We report the case of an adult male presenting in shock caused by spontaneous rupture of a pathologically normal spleen. One day before his presentation he had received a single subcutaneous injection of enoxaparin. This was the patient's only clearly identifiable risk factor for spontaneous splenic rupture. Nontraumatic splenic rupture should be included in the differential diagnosis of shock.