scholarly journals Reversal Activity and Toxicity of Heparin-Binding Copolymer after Subcutaneous Administration of Enoxaparin in Mice

2021 ◽  
Vol 22 (20) ◽  
pp. 11149
Author(s):  
Justyna Swieton ◽  
Joanna Miklosz ◽  
Shin-Ichi Yusa ◽  
Krzysztof Szczubialka ◽  
Dariusz Pawlak ◽  
...  

Uncontrolled bleeding after enoxaparin (ENX) is rare but may be life-threatening. The only registered antidote for ENX, protamine sulfate (PS), has 60% efficacy and can cause severe adverse side effects. We developed a diblock copolymer, heparin-binding copolymer (HBC), that reverses intravenously administered heparins. Here, we focused on the HBC inhibitory activity against subcutaneously administered ENX in healthy mice. BALB/c mice were subcutaneously injected with ENX at the dose of 5 mg/kg. After 110 min, vehicle, HBC (6.25 and 12.5 mg/kg), or PS (5 and 10 mg/kg) were administered into the tail vein. The blood was collected after 3, 10, 60, 120, 360, and 600 min after vehicle, HBC, or PS administration. The activities of antifactors Xa and IIa and biochemical parameters were measured. The main organs were collected for histological analysis. HBC at the lower dose reversed the effect of ENX on antifactor Xa activity for 10 min after antidote administration, whereas at the higher dose, HBC reversed the effect on antifactor Xa activity throughout the course of the experiment. Both doses of HBC completely reversed the effect of ENX on antifactor IIa activity. PS did not reverse antifactor Xa activity and partially reversed antifactor IIa activity. HBC modulated biochemical parameters. Histopathological analysis showed changes in the liver, lungs, and spleen of mice treated with HBC and in the lungs and heart of mice treated with PS. HBC administered in an appropriate dose might be an efficient substitute for PS to reverse significantly increased anticoagulant activity that may be connected with major bleeding in patients receiving ENX subcutaneously.

Author(s):  
Alexander P. Benz ◽  
Lizhen Xu ◽  
John W. Eikelboom ◽  
Saskia Middeldorp ◽  
Truman J. Milling ◽  
...  

Abstract Background Andexanet alfa (andexanet) is approved for specific anticoagulation reversal in patients with life-threatening or uncontrolled bleeding during treatment with rivaroxaban or apixaban. There is limited experience with andexanet in patients with acute bleeding on edoxaban. Methods Patients with acute major bleeding within 18 hours of edoxaban intake were prospectively enrolled. Patients received a bolus and 2-hour follow-on infusion of andexanet. The co-primary efficacy outcomes were change in antifactor Xa activity and the percentage of patients achieving excellent or good hemostasis, 12 hours after andexanet treatment. Efficacy was analyzed in patients with confirmed major bleeding and baseline antifactor Xa activity ≥40 ng/mL. Safety was analyzed in all patients. Results Thirty-six patients (mean age: 82 years, 61.1% male and 91.7% with atrial fibrillation) with acute major bleeding on edoxaban received andexanet. The primary site of bleeding was intracranial in 29 patients (80.6%). In the efficacy population (n = 28), median antifactor Xa activity decreased from 121.1 (interquartile range [IQR]: 70.3–202.4) ng/mL at baseline to 24.0 (IQR: 77.7–83.7) ng/mL at the end of andexanet bolus (median decrease: 68.9%, 95% confidence interval [CI]: 56.1–77.7%). Excellent or good hemostasis at 12 hours was achieved in 78.6% (95% CI: 59.0–91.7%) of patients. Within 30 days, four patients (11.1%) experienced a thrombotic event and four others (11.1%) died. Conclusion In patients with acute major bleeding on edoxaban, andexanet significantly decreased antifactor Xa activity. Hemostatic efficacy was similar to that observed in patients with bleeding on rivaroxaban or apixaban. Thrombotic events occurred at a rate expected in such patients.


1993 ◽  
Vol 70 (03) ◽  
pp. 454-457 ◽  
Author(s):  
Claus Bregengaard ◽  
Ole Nordfang ◽  
Per Østergaard ◽  
Jens G L Petersen ◽  
Giorgio Meyn ◽  
...  

SummaryTissue factor pathway inhibitor (TFPI) is a feed back inhibitor of the initial activation of the extrinsic pathway of coagulation. In humans, injection of heparin results in a 2-6 fold increase in plasma TFPI and recent studies suggest that TFPI may be important for the anticoagulant activity of heparin. Full length (FL) TFPI, but not recombinant two-domain (2D) TFPI, has a poly cationic C-terminus showing very strong heparin binding. Therefore, we have investigated if heparin affects the pharmacokinetics of TFPI with and without this C-terminus.FL-TFPI (608 U/kg) and 2D-TFPI (337 U/kg) were injected intravenously in rabbits with and without simultaneous intravenous injections of low molecular weight heparin (450 anti-XaU/kg).Heparin decreased the volume of distribution and the clearance of FL-TFPI by a factor 10-15, whereas the pharmacokinetics of 2D-TFPI were unaffected by heparin. When heparin was administered 2 h following TFPI the recovery of FL-TFPI was similar to that found in the group receiving the two compounds simultaneously, suggesting that the releasable pool of FL-TFPI is removed very slowly in the absence of circulating heparin.


1993 ◽  
Vol 69 (02) ◽  
pp. 157-163 ◽  
Author(s):  
Irving Fox ◽  
Adrian Dawson ◽  
Peter Loynds ◽  
Jane Eisner ◽  
Kathleen Findlen ◽  
...  

SummaryHirulog™ (BG8967) is a direct thrombin inhibitor built by rational design using the protein hirudin as a model (Maraganore et al. [1990]; Biochemistry 29: 7095–101). In order to evaluate the therapeutic potential for hirulog in the management of thrombotic disease, the tolerability and anticoagulant activity of the agent were examined in a study of human volunteers.In a randomized, placebo-controlled study (n = 54), the intravenous infusion of hirulog over 15 min showed a rapid, dose-dependent prolongation of activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). There was a corresponding dose-dependent increase in plasma hirulog levels. The peptide was rapidly cleared with a half-life of 36 min and a total body clearance rate for the peptide of 0.43 1 kg−1 h−1. Similar activity was observed following subcutaneous injection but with sustained pharmacodynamic and pharmacokinetic behavior. There was a significant correlation between pharmacokinetic and pharmacodynamic variables for both intravenous (r = 0.8, p <0.001) and subcutaneous administration (r = 0.7, p = 0.002).To evaluate the possible interactions of aspirin on the tolerability and anticoagulant activity of intravenous hirulog, a cross-over design was employed in eight subjects. Aspirin administration did not modify the peptide’s activity. At the administered dose of 0.6 mg kg−1 h−1 for 2 h, hirulog infusion prolonged APTT from 230 to 260% baseline. The infusion of hirulog in subjects who had received aspirin was not associated with any significant changes in the template bleeding time.The final phase of the study examined the activity and tolerability of hirulog in ten subjects during prolonged intravenous infusions for up to 24 h. The peptide (0.3 mg kg−1 h−1) exhibited sustained anticoagulant activity with no evidence for a cumulative effect. During hirulog infusion, APTT was prolonged from 210 to 250% baseline.In all phases of the study, hirulog administration was generally well-tolerated.Our observations show that hirulog is an active antithrombin agent with excellent tolerability in humans. As a direct thrombin inhibitor, hirulog provides a novel approach for the management of thrombotic disease.


1993 ◽  
Vol 70 (04) ◽  
pp. 625-630 ◽  
Author(s):  
Edward Young ◽  
Benilde Cosmi ◽  
Jeffrey Weitz ◽  
Jack Hirsh

SummaryThe non-specific binding of anticoagulantly-active heparin to plasma proteins may influence its anticoagulant effect. We used low affinity heparin (LAH) essentially devoid of anti-factor Xa activity to investigate the extent and possible mechanism of this non-specific binding. The addition of excess LAH to platelet-poor plasma containing a fixed amount of unfractionated heparin doubled the anti-factor Xa activity presumably because it displaces anticoagulantly-active heparin from plasma proteins. Although dextran sulfates of varying molecular weights also increased the anti-factor Xa activity, less sulfated heparin-like polysaccharides had no effect. These findings suggest that the ability to displace active heparin from plasma protein binding sites is related to charge and may be independent of molecular size. In contrast to its effect in plasma containing unfractionated heparin, there was little augmentation in anti-factor Xa activity when LAH was added to plasma containing low molecular weight heparin (LMWH), indicating that LMWH binds less to plasma proteins than unfractionated heparin. This concept is supported by studies comparing the anticoagulant activity of unfractionated heparin and LMWH in plasma with that in buffer containing antithrombin III. The anti-factor Xa activity of unfractionated heparin was 2-fold less in plasma than in the purified system. In contrast, LMWH had identical anti-factor Xa activity in both plasma and buffer, respectively. These findings may be clinically relevant because the recovered anti-factor Xa activity of unfractionated heparin was 33% lower in plasma from patients with suspected venous thrombosis than in plasma from healthy volunteers. The reduced heparin recovery in patient plasma reflects increased heparin binding to plasma proteins because the addition of LAH augmented the anti-factor Xa activity. In contrast to unfractionated heparin, there was complete recovery of LMWH added to patient plasma and little increase of anti-factor Xa activity after the addition of LAH. These findings may explain why LMWH gives a more predictable dose response than unfractionated heparin.


1995 ◽  
Vol 73 (02) ◽  
pp. 219-222 ◽  
Author(s):  
Manuel Monreal ◽  
Luis Monreal ◽  
Rafael Ruiz de Gopegui ◽  
Yvonne Espada ◽  
Ana Maria Angles ◽  
...  

SummaryThe APTT has been considered the most suitable candidate to monitor the anticoagulant activity of hirudin. However, its use is hampered by problems of standardization, which make the results heavily dependent on the responsiveness of the reagent used. Our aim was to investigate if this different responsiveness of different reagents when added in vitro is to be confirmed in an ex vivo study.Two different doses of r-hirudin (CGP 39393), 0.3 mg/kg and 1 mg/kg, were administered subcutaneously to 20 New Zealand male rabbits, and the differences in prolongation of APTT 2 and 12 h later were compared, using 8 widely used commercial reagents. All groups exhibited a significant prolongation of APTT 2 h after sc administration of hirudin, both at low and high doses. But this prolongation persisted 12 h later only when the PTTa reagent (Boehringer Mannheim) was used. In general, hirudin prolonged the APTT most with the silica- based reagents.In a further study, we compared the same APTT reagents in an in vitro study in which normal pooled plasma was mixed with increasing amount of hirudin. We failed to confirm a higher sensitivity for silica- containing reagents. Thus, we conclude that subcutaneous administration of hirudin prolongs the APTT most with the silica-based reagents, but this effect is exclusive for the ex vivo model.


2020 ◽  
Author(s):  
Dharmabandhu Nandadeva Samarasekera ◽  
Umesh Jayarajah ◽  
Isuru S Almeida

Abstract Objective Fistulae-in-ano with a specific aetiology such as TB and Crohn’s are usually complex and challenging to treat. This study was aimed to determine the yield of routine histological analysis in fistula-in-ano, in detecting specific aetiology. Histopathology reports of all patients without a previous diagnosis, who underwent surgery for fistulae-in-ano were retrospectively analysed. Results A total of 215 patients [median age:40 years(range:14–73), males = 178(82.8%)] were analysed. The majority(75%,n = 161) were simple fistulae and recurrent(67%,n = 145). Histological evaluation revealed inflamed granulation tissue in 94.9%(n = 204) of patients. Five(2.3%) patients had conclusive evidence of Crohn’s disease and three(1.4%) had tuberculosis. One patient(0.5%) had evidence of adenocarcinoma with mucinous differentiation. Significant proportion of fistula with a specific aetiology were complex fistulae (82%vs.22%,p < 0.001) and associated with abscess/collections (45.5%vs.11.8%, p < 0.001). Age, type of fistula, level of internal opening, recurrence and presence of haemorrhoids were comparable in those with and without a specific aetiology. One patient with Crohn’s and those with TB did not have any associated symptoms to suggest the diagnosis. Routine histopathological analysis in patients presenting with fistula in-ano should be performed as clinical prediction based on the nature of fistula may not be always accurate.


2009 ◽  
Vol 77 (9) ◽  
pp. 3578-3587 ◽  
Author(s):  
Roberta Colicchio ◽  
Susanna Ricci ◽  
Florentia Lamberti ◽  
Caterina Pagliarulo ◽  
Chiara Pagliuca ◽  
...  

ABSTRACT Experimental animal models of bacterial meningitis are useful to study the host-pathogen interactions occurring at the cerebral level and to analyze the pathogenetic mechanisms behind this life-threatening disease. In this study, we have developed a mouse model of meningococcal meningitis based on the intracisternal inoculation of bacteria. Experiments were performed with mouse-passaged serogroup C Neisseria meningitidis. Survival and clinical parameters of infected mice and microbiological and histological analysis of the brain demonstrated the establishment of meningitis with features comparable to those of the disease in humans. When using low bacterial inocula, meningococcal replication in the brain was very efficient, with a 1,000-fold increase of viable counts in 18 h. Meningococci were also found in the blood, spleens, and livers of infected mice, and bacterial loads in different organs were dependent on the infectious dose. As glutamate uptake from the host has been implicated in meningococcal virulence, mice were infected intracisternally with an isogenic strain deficient in the ABC-type l-glutamate transporter GltT. Noticeably, the mutant was attenuated in virulence in mixed infections, indicating that wild-type bacteria outcompeted the GltT-deficient meningococci. The data show that the GltT transporter plays a role in meningitis and concomitant systemic infection, suggesting that meningococci may use l-glutamate as a nutrient source and as a precursor to synthesize the antioxidant glutathione.


2007 ◽  
Vol 98 (07) ◽  
pp. 148-154 ◽  
Author(s):  
Ellen Brodin ◽  
Baldur Sveinbjörnsson ◽  
John-Bjarne Hansen ◽  
Anders Vik

SummaryHeparin treatment may induce osteoporosis by an unknown mechanism. Osteoprotegerin (OPG), a glycoprotein with a heparin-binding site, is a decoy receptor for RANKL which is responsible for osteoclast development.The objective was to investigate the effect of unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH; dalteparin) on plasma levels of OPG.Twenty-two male students were allocated to the following treatment regimens; A) one bolus of 5,000 IU UFH iv followed by infusion of 450 IU/kg/24 h for 72 hours (n=7), B) sc administration of LMWH (200 IU/kg) once daily for 72 hours (n=8), C) sc administration of 100 IU/kg LMWH once (n=8), D) sc administration of 250 IU/kg UFH once (n=7), E) control infusion of saline for 12 hours (n=7). UFH boluses of 5,000 IU were given 4 and 24 hours after cessation of regimens A and B. Bolus injection of UFH iv caused a prompt increase in plasma OPG from 0.68 ng/ml (SD=0.09) to 1.13 ng/ml (SD=0.30) (p=0.003) which declined during the continuous UFH infusion and reached baseline values after 8 hours (regime A). Similar increases in plasma OPG was obtained by repeated UFH boluses after cessation of treatment. Subcutaneous administration of LMWH (200 IU/kg) caused a modest, but significant (p=0.002) increase in plasma OPG similar to the mobilization by 250 IU/kg UFH sc, but the LMWH treatment caused a three-fold higher anti-Xa activity (p<0.001). We conclude that UFH causes a more pronounced vascular mobilization of OPG than LMWH, indicating that UFH has a higher affinity for OPG than LMWH.


2022 ◽  
Vol 58 (1) ◽  
pp. 37-41
Author(s):  
Adrienne M. Felix ◽  
Rebecca K. Davies

ABSTRACT A 4 mo old female intact boxer was presented because of polyuria, lethargy, and vomiting after ingestion of cholecalciferol rodenticide roughly 3 days prior. Blood work revealed an ionized hypercalcemia 2.23 mmol/L (reference range 1.04–1.33 mmol/L) on presentation. Because of financial limitations, the patient was unable to be hospitalized for standard of care. She was treated with a pamidronate infusion and discharged with medical management to include oral prednisone, furosemide, and subcutaneous fluids. The dog’s signs, body weight, and biochemical parameters were serially monitored over 3 wk as the ionized hypercalcemia resolved. To the authors’ knowledge, this is the first published report documenting a successful outpatient medical protocol for potentially life-threatening hypercalcemia secondary to cholecalciferol toxicosis in a puppy.


2021 ◽  
Vol 14 (8) ◽  
pp. e236983
Author(s):  
Kumar Nilesh ◽  
Swenil Shah ◽  
Amol Gautam ◽  
Sagar Thorat

Arteriovenous malformations (AVMs) are rare congenital disorders of vascular morphogenesis. These lesions are characterised by high vascular flow with risk of severe bleeding from accidental trauma or surgical manipulation. Although infrequent, potentially life-threatening and fatal oral bleeding has been reported during extraction of tooth associated with AVM. This paper presents a case of uncontrolled bleeding in an adult female patient undergoing mandibular anterior tooth extraction. The bleeding was related to undiagnosed soft tissue AVM in gingivobuccal space. Management of the case with review of previously reported similar cases is presented.


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