Fondaparinux: a suitable alternative in cases of delayed-type allergy to heparins and semisynthetic heparinoids? A study of 7 cases

Non-immediate heparin and heparinoid cutaneous allergic reactions: a role for fondaparinux

Non-immediate allergic cutaneous reactions to heparins have been increasingly reported, typically manifesting as large, eczematous plaques at sites of subcutaneous injection. Patients may demonstrate cross-reactivity between unfractionated heparin, low molecular weight heparin and semi-synthetic heparinoids, making finding an alternative difficult. Fondaparinux has been identified as a useful alternative in such patients; here we present the first two documented cases in Australia and a literature review.

A systematic review on the use of new anticoagulants in pregnancy

New anticoagulants such as direct factor Xa inhibitors and direct thrombin inhibitors have been recently developed, but their experience in pregnancy is limited. This review therefore aims to systematically search for studies on the use of these newer anticoagulants in pregnancy and the puerperal period. Searches were performed on electronic databases MEDLINE (from 1966), EMBASE (from 1974) and the Cochrane Library, until October 2011 using terms of 'pregnancy', 'puerperium', 'breastfeeding' and names of specific anticoagulants. The search yielded 561 citations and 11 studies (10 on fondaparinux, 1 on ximelagatran) were included. Newer anticoagulants (fondaparinux, hirudin and argatroban) on the limited evidence appear not to have adverse pregnancy outcomes, but there is currently no experience of new oral anticoagulants (rivaroxaban, apixaban, betrixaban or dabigatran) use in pregnancy. There is a need for reporting on new oral anticoagulation use in pregnancy to provide more information about the safety and risks to the fetus in utero.

Application, tolerance and safety of fondaparinux therapy in a German hospital: a prospective single-centre experience

INTRODUCTION

The pentasaccharide fondaparinux is widely approved for prophylaxis and treatment of thromboembolic diseases and therapy of acute coronary syndrome. It is also used off-label in patients with acute, suspected or antecedent heparin-induced thrombocytopenia (HIT). The aim of this prospective observational cohort study was to document fondaparinux' prescription practice, tolerance and therapy safety in a representative mixed German single-centre patient cohort.

PATIENTS AND METHODS

Between 09/2008 - 04/2009, 231 consecutive patients treated with fondaparinux were enrolled. Medical data were obtained from patient's records. The patients were clinically screened for thrombosis (Wells score), sequelae of HIT (4T's score), and bleeding complications (ISTH-criteria) and subjected to further assessment (i.e. sonography, HIT-diagnostics), if necessary. The mortality rate was assessed 30 days after therapy start.

RESULTS

Overall, 153/231 patients had a prophylactic, 74/231 patients a therapeutic, and 4/231 patients a successive prophylactic/therapeutic indication. In 11/231 patients fondaparinux was used due to suspected/antecedent HIT, in 5/231 patients due to a previous cutaneous delayed-type hypersensitivity to heparins. Other indications were rare. Three new/progressive thromboses were detected. No cases of HIT, major bleedings, or fatalities occurred.

CONCLUSIONS

Fondaparinux was well tolerated and was safe in prophylaxis and therapy; prescriptions mostly followed the current approval guidelines and were rarely related to HIT-associated indications (<5% of prescriptions), which is in contrast to previous study results in the U.S. (>94% of prescriptions were HIT-associated). A trend towards an individualised fondaparinux use based on the compound's inherent properties and the patients' risk profiles, i.e., antecedent HIT, bone fractures, heparin allergy, was observed.

Low allergenic potential with fondaparinux: results of a prospective investigation

OBJECTIVE

To determine the incidence and causes of skin reactions to the synthetic pentasaccharide fondaparinux.

PATIENTS AND METHODS

Patients who received prophylactic/therapeutic subcutaneous fondaparinux treatment for more than 7 days were prospectively examined for cutaneous adverse effects between September 1, 2008, and April 30, 2009. When indicated, other procedures, such as skin biopsy, allergy testing, and clinical/laboratory assessment for thrombosis and heparin-induced thrombocytopenia, were performed.

RESULTS

Overall, 231 patients were enrolled. No patient developed typical delayed type IV hypersensitivity (DTH) erythematous skin lesions. However, one female patient experienced abdominal pruritus at sites of injection. Histology revealed a mild lymphohistiocytic infiltrate, confirming a DTH reaction. Heparin-induced thrombocytopenia, as another possible underlying pathomechanism for cutaneous lesions, was ruled out clinically and serologically. Hence, the overall incidence of fondaparinux-induced allergic skin lesions was 0.4% (95% confidence interval, 0.01%-2.4%). No cross-allergies were observed in patients with DTH reaction to heparins.

CONCLUSION

Fondaparinux has a low allergenic potential. The incidence of allergic cutaneous DTH reactions is almost 20 times lower compared to that with commonly used heparins. These results, together with the known low prevalence of secondary thrombotic events or heparin-induced thrombocytopenia during fondaparinux therapy, suggest that in selected patients fondaparinux might substantially improve patient care, therapeutic safety, and cost-effectiveness of anticoagulant therapy.

TRIAL REGISTRATION

clinicaltrials.gov identifier: NCT00510432.

Incidence and causes of heparin-induced skin lesions

BACKGROUND

Little is known about the incidence and causes of heparin-induced skin lesions. The 2 most commonly reported causes of heparin-induced skin lesions are immune-mediated heparin-induced thrombocytopenia and delayed-type hypersensitivity reactions.

METHODS

We prospectively examined consecutive patients who received subcutaneous heparin (most often enoxaparin or nadroparin) for the presence of heparin-induced skin lesions. If such lesions were identified, we performed a skin biopsy, platelet count measurements, and antiplatelet-factor 4 antibody and allergy testing.

RESULTS

We enrolled 320 patients. In total, 24 patients (7.5%, 95% confidence interval [CI] 4.7%-10.6%) had heparin-induced skin lesions. Delayed-type hypersensitivity reactions were identified as the cause in all 24 patients. One patient with histopathologic evidence of delayed-type hypersensitivity tested positive for antiplatelet-factor 4 antibodies. We identified the following risk factors for heparin-induced skin lesions: a body mass index greater than 25 (odds ratio [OR] 4.6, 95% CI 1.7-15.3), duration of heparin therapy longer than 9 days (OR 5.9, 95% CI 1.9-26.3) and female sex (OR 3.0, 95% CI 1.1-8.8).

INTERPRETATION

Heparin-induced skin lesions are relatively common, have identifiable risk factors and are commonly caused by a delayed-type hypersensitivity reaction (type IV allergic response).

Negative predictive value of drug skin tests in investigating cutaneous adverse drug reactions

BACKGROUND

Drug skin tests are useful in aetiological analyses of cutaneous adverse drug reactions to determine if the drug can be rechallenged, or to avoid a cross-reaction with a substitute drug.

OBJECTIVES

To evaluate the negative predictive value of drug skin tests.

METHODS

We retrospectively analysed the files of patients referred for drug reactions. We have enrolled those having strictly determined drug reactions with clinical features, delayed onset after drug intake, drug causality assessment, and negative drug skin tests followed by drug administration. Oral provocation tests or substitution tests with a drug of the same class as that suspected of causing the drug reactions were performed.

RESULTS

From 1957 files analysed, 200 patients were included. After 403 patch tests, 403 prick tests and 304 intradermal tests, which were all negative, 260 oral provocation tests and 143 substitution tests were done; 307 different drugs were rechallenged. There were 42 positive drug re-administrations in 27 oral provocation tests and 15 substitution tests. The negative predictive value of our drug skin tests was 89.6%. The negative predictive value for beta-lactams was 87% for oral provocation tests and 96% for substitution tests, and for corticosteroids it was 100% and 74%, respectively.

CONCLUSIONS

Negative drug skin tests do not eliminate the responsibility of a drug in drug reactions, and must be followed by drug re-administration under hospital surveillance.

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.

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.

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.

Hypersensitivity reactions to anticoagulant drugs: diagnosis and management options

Anticoagulants, including heparins, coumarins, hirudins, and some of the previously used plasma volume expanders, belong to the most widely used drugs. Hypersensitivity reactions from these agents are uncommon. However, they may have a considerable impact on patient safety and treatment decisions. Therefore, early diagnosis of potentially life-threatening adverse events and identification of alternatives is clinically important. This review contains an update on current knowledge about hypersensitivity reactions caused by the different anticoagulants. In addition, it discusses pathophysiologic mechanisms, diagnostic possibilities, and management options. The most common hypersensitivity reactions are erythematous plaques, occurring with a delay after subcutaneous application of heparins. Seldom they turn into maculopapular exanthema. Other hypersensitivity reactions are rare but may be life-threatening, e.g. skin necrosis because of heparin-induced thrombocytopenia. Skin and provocation tests with immediate and late readings are the most reliable diagnostic tools for heparin- or hirudin-induced urticaria/anaphylaxis or heparin-induced delayed plaques. If necrosis from heparins or coumarins is suspected, skin tests are contraindicated. In anaphylactic reactions caused by dextrans or hydroxyethyl starch skin tests are useless. Most in vitro tests have a low sensitivity and are not generally available. Therefore, in some anticoagulant-associated hypersensitivity reactions detailed allergologic investigation may help to identify safe treatment alternatives. However, several tests may be needed, and the procedures are usually time-consuming.

Fondaparinux as anticoagulant in a pregnant woman with heparin allergy

We report a patient who had a history of deep vein thrombosis in a previous pregnancy. She was treated with heparins without any reactions in the index pregnancy. Subsequently, when the patient became pregnant again, she developed an acute cutaneous reaction to the low molecular heparin enoxaparin 3 weeks after initiation of therapy. She developed a similar reaction to delteparin as well. She was therefore treated with warfarin until 36 weeks of gestation. Then she was treated with fondaparinux (Arixtra, Sanofi-Synthelabo, Paris, France) 2.5 mg daily for the remainder of the pregnancy. Delivery was at term by induction of labour. Fondaparinux was stopped on the day of the induction of labour. It was re-started 6 h post-delivery and the patient was anticoagulated with warfarin in the post-partum period. There were no bleeding tendencies or recurrences of thrombosis during fondaparinux therapy. Both mother and baby were well after delivery.

Eczema-like plaques secondary to enoxaparin

Low-molecular-weight heparins are used extensively in acute medicine. They are generally well tolerated but may cause a rare, eczema-like type IV hypersensitivity reaction. We report 3 cases of this eruption and speculate that it may be significantly under-reported due to misidentifying the causal drug, which may have serious consequences. We discuss treatment alternatives such as fondaparinux sodium, which may rarely cross-react.

Clinical update on contact allergy

PURPOSE OF REVIEW

The aim of this article is to review recent findings in contact allergy, regarding clinical research.

RECENT FINDINGS

The biocide methyldibromo glutaronitrile was identified to be an important sensitizer. Subsequently, it was banned from leave-on cosmetics in the European Union. Another group of important allergens that have been studied extensively included the fragrances oak moss absolute, isoeugenol, hydroxyisohexyl 3-cyclohexene carboxaldehyde and farnesol. A new fragrance mix II has been developed for standard testing, which includes the two latter compounds. Dose response studies have demonstrated broad individual variation of elicitation thresholds, dependent on the allergen concentration during induction, and other factors. Some unsuspected routes of exposure to allergens include oral, inhalational, connubial or airborne contact. Experimental studies provide a classification of newly introduced chemicals; increasingly, the local lymph node assay is supplementing and potentially replacing the guinea pig maximization test. Recent advances in occupational contact allergy include, for example, some attempts to improve diagnostics for epoxy resin and other plastic, glue, and cutting fluid components.

SUMMARY

Constant awareness for new allergens, confirmed by critical evaluation, standardization of patch test materials, and the identification of temporal patterns and subgroups at risk will improve both the diagnosis and prevention of allergic contact dermatitis.