Evaluation of Immunostimulatory Potential of Branded and US-Generic Enoxaparins in an In Vitro Human Immune System Model.

Low-molecular-weight heparins (LMWHs) have several positive therapeutic effects and can also form immunostimulatory complexes with plasma proteins, such as platelet factor 4 (PF4). We compared the innate response and functional profiles of branded and US-generic enoxaparins from 2 manufacturers in either native or PF4-bound forms in an in vitro model of human immunity. In an analysis of 2 product lots from each manufacturer and multiple separate batches of protein-heparin complexes, branded enoxaparin was shown to be consistently nonstimulatory for innate responses, whereas US-generic enoxaparins generated variable immunostimulatory profiles depending on the enoxaparin lot used to prepare the PF4-LMWH complexes. Production of tissue factor pathway inhibitor (TFPI), a physiologic heparin-induced inhibitor of tissue factor-induced coagulation that was used as a functional readout of biological activity of enoxaparins in these assays, was heightened in the presence of branded enoxaparin complexes, but its levels were variable in cultures treated with complexes containing US-generic enoxaparins. Analytical analyses suggest that the heightened immunostimulatory potential of some of the US-generic enoxaparin product lots could be tied to their capacity to form ultra-large and/or more stable complexes with PF4 than the other LMWHs included in this study. Although these distinct biological and analytical profiles might be related to the composition and/or consistency of branded and US-generic enoxaparins included in our data set, further studies are warranted to elucidate the pathophysiological relevance of these in vitro findings.

Allopurinol desensitization: a fast or slow protocol?

No disponible

Recurrent anaphylaxis due to enoxaparin

No disponible

Binding of heparin-dependent antibodies to PF4 modified by enoxaparin oligosaccharides: evaluation by surface plasmon resonance and serotonin release assay.

BACKGROUND: The minimal structural requirements of low-molecular-weight heparins that determine the risk of developing heparin-induced thrombocytopenia (HIT) are not fully defined. OBJECTIVES: The ability of enoxaparin-derived oligosaccharides (OS) to induce platelet activation and exposure of platelet-factor 4 (PF4) epitopes recognized by antibodies developed in HIT was studied by surface plasmon resonance (SPR) and serotonin release assay. RESULTS: Decasaccharides with ≥ 11 sulfate groups induced platelet activation in the presence of plasma from patients with confirmed HIT. Serotonin release of > 80% without full inhibition at 100 µg mL(-1) was achieved with decasaccharides containing 14 or 15 sulfate groups, 2 dodecasaccharides and 2 tetradecasaccharides. An SPR method was developed using purified PF4 immobilized on carboxymethylated dextran. Antibodies from all HIT samples bound to PF4/heparin in SPR assays with resonance units (RU) ratio of 109-173 with HIT plasma vs. 88-93 with control plasma. RU ratios > 100 were measured when PF4 was pre-incubated with OS with ≥ 10 saccharide units and one octasaccharide containing 10 sulfate groups. RU ratios > 140, similar to those measured when PF4 was pre-incubated with unfractionated heparin or enoxaparin, were obtained with purified dodeca- and tetradecasaccharides. RU values strongly correlated with the number of sulfate groups in the decasaccharides tested (r = 0.93, P = 0.02). CONCLUSIONS: LMWHs with fragments > 10 saccharides and a large number of sulfate groups are more likely to be associated with a higher risk of HIT. These structure-activity relationships were independent of the ability of the OS to bind antithrombin.

An open label, non-randomized, prospective clinical trial evaluating the immunogenicity of branded enoxaparin versus biosimilars in healthy volunteers.

INTRODUCTION: Compositional variations among biosimilar enoxaparin could lead to a differential immunogenic response between these preparations. METHODS: Enoxaparin (Clexane, n = 110) and a biosimilar version (Cutenox, n = 110) were administered to healthy volunteers in Brazil, 40 mg subcutaneous (SQ), daily, for 10 days. Blood was collected at baseline, days 1 and 10, and analyzed for antiheparin/PF4 antibody (AHPF4 antibodies) titers and subtypes by enzyme-linked-immunosorbent serologic assay (ELISA). RESULTS: Low-molecular-weight heparin (LMWH) treatment resulted in AHPF4 antibodies generation, with differences on day 10 (P < .05). Antibody subtyping (immunoglobulin [Ig] G, IgA, IgM) demonstrated different profiles between LMWH with statistical significance for IgG (Clexane 10 = 0.21 ± 0.06, Cutenox 10 = 0.28 ± 0.10, P < .0001) and IgA (Clexane 10 = 0.15 ± 0.02, versus Cutenox 10 = 0.13 ± 0.02, P < .0001) on day 10, with a significant drug effect (P < .0001) and significant time by drug interaction (P = .0009). All antibody titers were stated in terms of optical density (OD) units. CONCLUSION: LMWHs immunogenic potential varies to generate AHPF4 antibodies and subtypes and cross-reactivity with preformed antibodies. Such parameters may be useful in defining the biosimilar LMWHs bioequivalence. Future studies evaluating the immunogenicity of biosimilar drugs are warranted.

Anti-PF4/heparin antibody formation postorthopedic surgery thromboprophylaxis: the role of non-drug risk factors and evidence for a stoichiometry-based model of immunization.

BACKGROUND: Heparin-induced thrombocytopenia is an antibody-mediated disorder exhibiting variable frequency in different clinical settings. Antibodies recognize PF4/heparin complexes formed at optimal stoichiometric molar ratios. OBJECTIVE: To identify clinical factors influencing risk of anti-PF4/heparin immunization. PATIENTS/METHODS: We performed observational studies and exploratory analyses of the frequency of anti-PF4/heparin antibody formation in 6324 patients who received enoxaparin or fondaparinux in four randomized controlled trials of postorthopedic surgery thromboprophylaxis. Variables included surgery type (knee vs. hip), timing of first anticoagulant dose (pre- vs. postsurgery), circumstances of surgery (elective vs. hip fracture), anticoagulant (enoxaparin vs. fondaparinux) and body-mass index (BMI). We applied a stoichiometry-based model that predicts immunization risk based on expected differences in PF4/anticoagulant ratios in different settings, and specifically used this model to predict the effect of increasing BMI quartiles upon relative risk (RR) of immunization for fondaparinux vs. enoxaparin. RESULTS: Anti-PF4/heparin immunization was more frequent after knee vs. hip surgery (particularly for enoxaparin), and when enoxaparin was given post- rather than pre-elective surgery; however, the opposite occurred with hip fracture surgery, that is, antibody formation was more frequent when enoxaparin or fondaparinux was given presurgery. The RR of immunization for fondaparinux vs. enoxaparin decreased significantly for increasing BMI quartiles, an effect predominantly because of increasing immunization with enoxaparin at increasing BMI quartiles. CONCLUSIONS: Several non-drug factors--including type and circumstances of surgery, timing of first anticoagulant dose and BMI--influence risk of anti-PF4/heparin antibody formation, consistent with a stoichiometry-based immunization model of PF4 and anticoagulant ratios occurring during the early peri-operative period.

P-selectin/ PSGL-1 inhibitors versus enoxaparin in the resolution of venous thrombosis: a meta-analysis.

BACKGROUND: P-selectin antagonism has been shown to decrease thrombogenesis and inflammation in animal models of deep venous thrombosis (DVT). OBJECTIVE: To determine the effectiveness of P-selectin inhibitors versus saline and enoxaparin in venous thrombus resolution in nonhuman primate models of venous thrombosis. METHODS: Studies reporting vein re-opening, inflammation expressed as Gadolinium enhancement and coagulation parameters were searched in the literature and pooled into a meta-analysis using an inverse variance with random effects. RESULTS: Five studies were identified comparing P-selectin/ PSGL-1 inhibitors versus saline or enoxaparin regarding venous thrombosis resolution. Vein re-opening was significantly higher on P-selectin/ PSGL-1 compounds, when compared to saline (Inverse Variance [IV] 95% CI; 44.37 [17.77-70.96], p=0.001, I(2)=97%) and similar to enoxaparin (IV 95% CI; 5.03 [-8.88-18.95], p=0.48, I(2)=41%). Inflammation, reflected as Gadolinium enhancement at magnetic resonance venography (MRV), was significantly decreased in the P-selectin treated group when compared to saline (IV 95% CI; -17.84 [-14.98-(-8.30)], p<0.00001, I(2)=80%). No significant differences on vein wall inflammation were observed between P-selectin/ PSGL-1 inhibitors and enoxaparin treated animals (IV95% CI; -3.59 [-10.67-3.48], p=0.32, I(2)=66%). In addition, there was no differences in the coagulation parameters (aPTT, TCT, BT, D-Dimer, fibrinogen, platelets) between P-selectin/ PSGL-1 inhibitors and enoxaparin (IV 95% CI; -1.12[-2.36-0.11], p=0.07, I(2)=92%), although there was a trend showing less of a prolongation in TCT with P-selectin/PSGL-1 inhibitors compared to enoxaparin (p<0.0001). CONCLUSION: P-selectin antagonism successfully paralleled the low-molecular-weight-heparin enoxaparin, for the treatment of DVT in nonhuman primate models, by decreasing both thrombus burden and inflammation without causing any bleeding complications and without increasing coagulation times.

Heparin-induced thrombocytopenia in a patient with lung embolism and left-sided pneumonia: a case report.

A case of a 73-year obese female with arterial hypertension, periodical metrorrhagia, polydipsia, and polyuria is presented. The patient was admitted to the hospital because of increasing dyspnea, cough, subfebrile body temperature, and decreasing exercise tolerance. Physical examination and laboratory tests were suggestive for massive lung embolism. Low molecular heparin was started and after 5 days' therapy, heparin-induced thrombocytopenia was diagnosed.

[Delayed hypersensitivity to heparins and heparinoids]. / Hypersensibilité retardée aux héparines et heparinoïdes.

Delayed hypersensitivity to heparins and heparinoïd is a problem for prophylaxis of thrombo embolic diseases. The hirudins did not seem to have any cross-reactivity with the two others groups of anticoagulants. We present two clinical cases of delayed type reactions to heparins and heparinoïd and we reviewed the literature about adverse reactions to low molecular weight heparins and the alternative possibilities.

Antifactor Xa activity in intensive care patients receiving thromboembolic prophylaxis with standard doses of enoxaparin.

BACKGROUND: Low-molecular-weight heparins (LMWHs) have become increasingly used to prevent thromboembolic complications in intensive care patients. Unlike in medical and surgical patients, no data on the anticoagulant effectiveness of standard LMWH dosages exist in intensive care patients. Therefore, we prospectively investigated antifactor Xa (aFXa) levels after subcutaneous administration of 40 mg of enoxaparin in 89 intensive care patients over a 24-h period. METHODS: AFXa levels were measured before, 4, 12 and 24 h after subcutaneous administration of enoxaparin. Laboratory parameters including prothrombin time, activated partial thromboplastin time, antithrombin III, fibrinogen as well as platelet count were collected at same intervals. Demographics included age, sex, height, weight, body mass index, admission diagnosis, a thromboembolic risk score and a modified Goris multiple organ dysfunction score. RESULTS: At 4, 12 and 24 h, 56.5%, 39.3% and 12.6% of the study patients were within recommended antithrombotic aFXa levels (0.1-0.3 U ml(-1)). Presence of multiple organ dysfunction as well as high body weight were significantly correlated with low aFXa levels. CONCLUSION: European standard dosages of 40 mg of enoxaparin once daily proved to be ineffective in achieving recommended antithrombotic aFXa levels in intensive care patients. This was most pronounced in patients with high body weight and presence of multiple organ dysfunction.

Enoxaparin-associated dermal necrosis: a consequence of cross-reactivity with heparin-mediated antibodies.

OBJECTIVE: To describe a patient with enoxaparin-induced dermal necrosis and to review previously reported cases of skin manifestations associated with low-molecular-weight heparins. CASE SUMMARY: A 43-year-old white woman with adult respiratory distress syndrome developed localized dermal necrosis and thrombocytopenia secondary to subcutaneous administration of unfractionated heparin. Upper extremity thrombi that had developed after administration of subcutaneous heparin at an outside hospital were treated with subcutaneous enoxaparin. Although platelet counts remained stable during enoxaparin therapy, dermal necrosis developed at the injection site. Parenteral anticoagulant therapy was discontinued and the necrotic lesions secondary to enoxaparin resolved with minimal local care. DISCUSSION: Numerous cases of dermal necrosis secondary to heparin administration have been reported while this reaction secondary to enoxaparin use has been reported only briefly. It has been postulated that dermal necrosis secondary to heparin is associated with heparin-induced thrombocytopenia and is a result of heparin-mediated thrombosis in the microvasculature. Antibodies to heparin have cross-reactivity with enoxaparin; therefore, dermal necrosis secondary to enoxaparin may occur by a similar mechanism. CONCLUSIONS: Although enoxaparin-associated dermal necrosis appears to be a rare occurrence, we advise against the use of enoxaparin or other low-molecular-weight heparins in patients with a previous history of heparin-associated thrombocytopenia or heparin-induced dermal necrosis.

The glycoprotein IIb/IIIa antagonist c7E3 inhibits platelet aggregation in the presence of heparin-associated antibodies.

PURPOSE: Heparin-associated antibodies (HAAb), in the presence of heparin, can cause platelet activation and aggregation. The purpose of this study was to assess whether a platelet glycoprotein (GP) IIb/IIIa receptor antagonist, c7E3, would inhibit platelet aggregation in the presence of HAAb. If aggregation is inhibited by c7E3, enzyme-linked immunosorbent assays (ELISA) would be done to determine whether c7E3 interfered with the binding of heparin and the HAAb. METHODS: HAAb-positive plasmas from 21 patients (determined by platelet aggregation assays) were studied. Normal donor platelet-rich plasmas (PRP) were incubated (1 minute) with either saline solution or 3 microg/ml of c7E3. Platelet-poor plasma from patients with HAAb and one of three sources of heparin (25 microl, 10 U/ml; porcine heparin, bovine heparin, and low molecular weight heparin [enoxaparin]) were added to the PRP mixture. Aggregation was determined using a platelet aggregometer by measuring time to aggregation, the slope of the aggregation curve, and the percent change in optical density. RESULTS: Platelet aggregation occured in 100%, 100%, and 95% of the saline solution incubations exposed to porcine heparin, bovine heparin, and enoxaparin, respectively. Incubation with c7E3 caused 100% inhibition of platelet aggregation in plasma exposed to porcine heparin, bovine heparin, and enoxaparin. The optical density curves obtained from the ELISA, which were dependent on the binding of HAAb to heparin, were not significantly different when c7E3 was compared to buffer alone. CONCLUSIONS: The GP IIb/IIIa receptor antagonist, c7E3, inhibits HAAb-induced platelet aggregation via a mechanism that does not appear to interfere with the binding between heparin and HAAb. Clinical trials are warranted to assess whether GP IIb/IIIa antagonists may allow patients with HAAb to safely receive heparin.