Efficacy and safety of bemiparin compared with enoxaparin in the prevention of venous thromboembolism after total knee arthroplasty: a randomized, double-blind clinical trial

Ranking the efficacy of anticoagulants for the prevention of venous thromboembolism after total hip or knee arthroplasty: A systematic review and a network meta-analysis

BACKGROUND

Anticoagulants are essential in the prevention of venous thromboembolism. However, the effectiveness and safety of different anticoagulants have always been controversial. Therefore, we aimed to expand the sample of anticoagulant results and rank the efficacy and safety of 19 anticoagulants in the prevention of venous thromboembolism when total knee or total hip arthroplasty procedure is performed.

METHODS

A systematic review and network meta-analysis of randomized trials of adult patients undergoing total hip or knee arthroplasty were conducted. The trials were identified from PubMed, Web of Science, Cochrane Library, and Embase databases, in which anticoagulants were used as interventions randomized controlled trial. The incidence of venous embolism and bleeding are the key outcomes of assessing the efficacy of intervention drugs. We used the Physical Therapy Evidence Database (PEDro) to assess risk bias and used pairwise comparison and network meta-analysis with random effects to estimate the summary relative risk. The study has been registered with PROSPERO, number CRD42020200747.

RESULTS

From the 4083 identified manuscripts, 45,067 participants from 53 randomized trials were included in the analysis and randomly assigned to 19 anticoagulants. With Enoxaparin as a control, Rivaroxaban (risk difference 0.07, 95 % credible interval 0.06 to 0.08), Edoxaban (RD 0.09, 95 % CrI 0.08 to 0.11), and Apixaban (RD 0.05, 95 % CrI 0.04 to 0.06) had the best effect in preventing VTE. However, in terms of comprehensive bleeding rate, Apixaban, Edoxaban, and Darexaban were the most effective and stable. Although effective in preventing VTE, bleeding remains relatively high in Rivaroxaban. Enoxaparin is low-molecular-weight heparin that is widely used in clinics, and although its overall efficacy is not the best, its efficacy and safety are very stable.

CONCLUSION

According to the available data, Apixaban, Edoxaban, and Darexaban are better than any anticoagulants in the prevention of VTE and bleeding during total knee or total hip arthroplasty. In our study, Fondaparinux, Eribaxaban, Dalteparin, Betrixaban, Bemiparin, Reviparin, Acenocoumarol, and Tinzaparin were scarce in the included studies, therefore, more evidence is needed to prove their efficacy and safety.

Randomized Trial of Deep Vein Thrombosis Chemoprophylaxis with Bemiparin and Enoxaparin in Patients with Moderate to High Thrombogenic Risk Undergoing Plastic and Reconstructive Surgery Procedures

BACKGROUND

Deep vein thrombosis (DVT) is a common complication during postoperative convalescence characterized by hypercoagulability, vascular endothelium damage and blood stasis. It increases noticeably in peri/postoperative phases of surgery procedures. Pulmonary embolism secondary to iliofemoral DVT is a frequent cause of death.

METHODS

Adult patients scheduled for plastic and reconstructive surgery (PRSx) with moderate to high thrombogenic risk were selected. We evaluated the efficacy and safety of bemiparin compared to enoxaparin as chemoprophylaxis for DVT. Following balanced general anesthesia techniques, patients were randomly assigned for subcutaneous enoxaparin 40 IU (Group-E) or bemiparin 3500 IU (Group-B) q24h starting 6 h after procedure conclusion for at least 10 days. All patients were evaluated for DVT through Doppler ultrasound mapping of the lower limbs.

RESULTS

Seventy-eight patients were evaluated, mostly women (83%), physical status ASA II (59%), ASA III (10%); Caprini's thrombogenic risk score 3-4 (moderate) 58%, 5-6 (high) 29%, > 6 (too high) 13%; demographics, clinical variables and scores were similar between groups. Median drainage time in breast surgery was 4 days in both groups (p = 0.238). In the case of abdominal surgery, median was 14 days in Group-E versus 13 days in Group-B (p = 0.059). No DVT was detected in either group.

CONCLUSIONS

DVT was prevented with bemiparin, without significant bleeding increase nor adverse events; moreover, the cost of bemiparin is lower than enoxaparin. Bemiparin can be considered as alternative drug for DVT chemoprophylaxis in PRSx procedures.

LEVEL OF EVIDENCE III

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Preventive Effects of Different Drugs on Asymptomatic Lower Extremities Deep Venous Thrombosis After Artificial Joint Replacement: A Mixed Treatment Comparison

This network meta-analysis aims to compare the preventive effects of 8 drugs (edoxaban, dabigatran, apixaban, rivaroxaban, warfarin, bemiparin, ximelagatran, and enoxaparin) on asymptomatic deep venous thrombosis (DVT) of lower extremities after artificial joint replacement. PubMed, Cochrane Library, and Embase were searched from their inception through October 2015 for randomized controlled trials comparing 8 drugs for the prevention of asymptomatic DVT of lower extremities after artificial joint replacement. Network meta-analysis combined the direct and indirect evidence to evaluate odd ratios (ORs) and surface under the cumulative ranking curves values. A total of 15 randomized controlled trials satisfying the inclusion criteria were enrolled. Edoxaban, apixaban, and rivaroxaban had poorer preventive effects on asymptomatic DVT of lower extremities after undergoing artificial joint replacement when compared with warfarin [OR = 0.16, 95% confidence interval (CI), 0.04-0.60; OR = 0.22, 95% CI, 0.07-0.64; OR = 0.16, 95% CI, 0.05-0.49, respectively]. When compared with enoxaparin, the preventive effects of edoxaban and rivaroxaban were poorer (OR = 0.37, 95% CI, 0.15-0.85; OR = 0.37, 95% CI, 0.21-0.59, respectively). The preventive effects of edoxaban and rivaroxaban were poorer than dabigatran (OR = 0.38, 95% CI, 0.14-0.99; OR = 0.38, 95% CI, 0.18-0.73, respectively). The surface under the cumulative ranking curves values showed that warfarin had better preventive effects on asymptomatic DVT of lower extremities after undergoing artificial joint replacement. Among the 8 drugs (edoxaban, dabigatran, apixaban, rivaroxaban, warfarin, bemiparin, ximelagatran, and enoxaparin), warfarin had better preventive effects on asymptomatic DVT of lower extremities after undergoing artificial joint replacement.

Surgical Technical Evidence Review for Elective Total Joint Replacement Conducted for the AHRQ Safety Program for Improving Surgical Care and Recovery

Background:

Use of enhanced recovery pathways (ERPs) can improve patient outcomes, yet national implementation of these pathways remains low. The Agency for Healthcare Research and Quality (AHRQ; funder), the American College of Surgeons, and the Johns Hopkins Medicine Armstrong Institute for Patent Safety and Quality have developed the Safety Program for Improving Surgical Care and Recovery—a national effort to catalyze implementation of practices to improve perioperative care and enhance recovery of surgical patients. This review synthesizes evidence that can be used to develop a protocol for elective total knee arthroplasty (TKA) and total hip arthroplasty (THA).

Study Design:

This review focuses on potential components of the protocol relevant to surgeons; anesthesia components are reported separately. Components were identified through review of existing pathways and from consultation with technical experts. For each, a structured review of MEDLINE identified systematic reviews, randomized trials, and observational studies that reported on these components in patients undergoing elective TKA/THA. This primary evidence review was combined with existing clinical guidelines in a narrative format.

Results:

Sixteen components were reviewed. Of the 10 preoperative components, most were focused on risk factor assessment including anemia, diabetes mellitus, tobacco use, obesity, nutrition, immune-modulating therapy, and opiates. Preoperative education, venous thromboembolism (VTE) prophylaxis, and bathing/Staphylococcus aureus decolonization were also included. The routine use of drains was the only intraoperative component evaluated. The 5 postoperative components included early mobilization, continuous passive motion, extended duration VTE prophylaxis, early oral alimentation, and discharge planning.

Conclusion:

This review synthesizes the evidence supporting potential surgical components of an ERP for elective TKA/THA. The AHRQ Safety Program for Improving Surgical Care and Recovery aims to guide hospitals and surgeons in identifying the best practices to implement in the surgical care of TKA and THA patients.

Effects of different anticoagulant drugs on the prevention of complications in patients after arthroplasty: A network meta-analysis

BACKGROUND

After arthroplasty treatment, some complications commonly occur, such as early revision, infection/dislocation, and venous thromboembolism (VTE). This study aims to use a network meta-analysis to compare effects of 9 anticoagulant drugs (edoxaban, dabigatan, apixaban, rivaroxaban, warfarin, heparin, bemiparin, ximelagatran, and enoxaparin) in preventing postoperative complications in arthroplasty patients.

METHODS

After retrieving PubMed, Embase, and Cochrane Library database from the inception to November 2016, randomized controlled trials were enrolled. The integration of direct and indirect evidences was performed to calculate odd ratios and the surface under the cumulative ranking curves. Nineteen eligible randomized controlled trials were included.

RESULTS

The network meta-analysis results showed that compared with warfarin, edoxaban, apixaban, and rivaroxaban had a lower incidence rate in asymptomatic deep venous thrombosis, which indicated that edoxaban, apixaban, and rivaroxaban had better effects on prevention. Similarly, in comparison to enoxaparin, edoxaban and rivaroxaban had better effect; rivaroxaban was better than ximelagatran in preventive effects. Compared with apixaban, edoxaban, dabigatan, rivaroxaban, and enoxaparin had a higher incidence rate in clinically relevant non-major bleeding, which showed that preventive effects were relatively poor. In addition, the results of the surface under the cumulative ranking curves showed that rivaroxaban and bemiparin worked best on symptomatic deep venous thrombosis and pulmonary embolism. In terms of bleeding, apixaban and warfarin had better preventive effects.

CONCLUSION

Our findings suggested that rivaroxaban may work better in terms of symptomatic deep venous thrombosis and pulmonary embolism, whereas apixaban had better preventive effects in bleeding.

Bemiparin versus Enoxaparin in the Prevention of Venous Thromboembolism among Intensive Care Unit Patients

Background:

Critically ill patients are considered a high-risk group for developing venous thromboembolism (VTE). Due to their impaired cardiopulmonary reserve, these VTEs may result in significant morbidity and mortality. In this study, we compared two types of low molecular weight heparin, enoxaparin, and bemiparin, as regards to their efficacy and safety in VTE prevention among Intensive Care Unit (ICU) patients.

Methods:

This study was a prospective, randomized trial of 100 critically ill patients who are at high risk for developing VTE were included in this study and assigned to receive subcutaneous injections of either 3500 international units (IU) anti-factor Xa of bemiparin sodium or 40 mg of enoxaparin given once a day and patient were followed for 60 days after initiation of anticoagulant therapy for the development of documented deep venous thrombosis (DVT) using bilateral lower limb venous duplex, documented pulmonary embolism using computed tomography pulmonary angiography, and complications related to injectant anticoagulant.

Results:

Confirmed DVT was observed in two patients (4%) in the bemiparin group compared with 10 patients (20%) in the enoxaparin group with P < 0.05. Confirmed pulmonary embolism (PE) was observed in seven patients (14%) in the enoxaparin group with no recorded cases of confirmed PE in the bemiparin group (P < 0.05). No deaths were recorded in either group. Adverse events such as ecchymosis or hematoma at the injection site were observed in one patient (2%) in the bemiparin group and eight patients (16%) in the enoxaparin group (P < 0.05). There was no significant statistical difference between both groups as regards other adverse effects and complications related to the injectant anticoagulant.

Conclusion:

Bemiparin was superior to enoxaparin as a prophylactic anticoagulant for VTE in critically ill patients with less adverse local complications at the injection site. The study was registered on www.clinicaltrials.gov. Registration ID: NCT02795065. Registered June 8, 2016.

Risk factors for venous thromboembolism of total hip arthroplasty and total knee arthroplasty: a systematic review of evidences in ten years

Background

Risk factors for venous thromboembolism (VTE) of total joint arthroplasty (TJA) have been examined by many studies. A comprehensive systematic review of recent findings of high evidence level in this topic is needed.

Methods

We conducted a PubMed search for papers published between 2003 and 2013 that provided level-I and level-II evidences on risk factors for VTE of TJA. For each potential factors examined in at least three papers, we summarize the the number of the papers and confirmed the direction of statistically significant associations, e.g. “risk factor” “protective factor” or “controversial factor”.

Results

Fifty-four papers were included in the systematic review. Risk factors found to be associated with VTE of both total hip arthroplasty and total knee arthroplasty included older age, female sex, higher BMI, bilateral surgery, surgery time > 2 hours. VTE history was found as a VTE risk factor of THA but an controversial factor of TKA. Cemented fixation as compared to cementless fixation was found as a risk factor for VTE only of TKA. TKA surgery itself was confirmed as a VTE risk factor compared with THA surgery.

Conclusions

This systematic review of high level evidences published in recent ten years identified a range of potential factors associated with VTE risk of total joint arthroplasty. These results can provide informations in this topic for doctors, patients and researchers.

Systematic review of randomized controlled trials of new anticoagulants for venous thromboembolism prophylaxis in major orthopedic surgeries, compared with enoxaparin

BACKGROUND

In the past 10 years, new anticoagulants (NACs) have been studied for venous thromboembolism (VTE) prophylaxis.

OBJECTIVE

To evaluate the risk/benefit profile of NACs versus enoxaparin for VTE prophylaxis in major orthopedic surgery.

METHODS

A systematic review of double-blind randomized phase III studies was performed. The search strategy was run from 2000 to 2011 in the main medical electronic databases in any language. Independent extraction of articles was performed by 2 authors using predefined data fields, including study quality indicators.

RESULTS

Fifteen published clinical trials evaluating fondaparinux, rivaroxaban, dabigatran, and apixaban were included. Primary efficacy (any deep vein thrombosis [DVT], nonfatal pulmonary embolism, or all-cause mortality) favored fondaparinux (relative risk [RR] 0.50; 95% CI, 0.39, 0.63) and rivaroxaban (RR, 0.50; 95% CI, 0.34, 0.73) over enoxaparin, although significant heterogeneity was observed in both series. The primary efficacy of dabigatran at 220 mg, apixaban, and bemiparin were similar, with RRs of 1.02 (95% CI, 0.86, 1.20), 0.63 (95% CI, 0.39, 1.01), and 0.87 (95% CI, 0.65, 1.17), respectively. The primary efficacy of dabigatran at 150 mg (RR, 1.20; 95% CI, 1.03, 1.41), was inferior to enoxaparin. The incidence of proximal DVT favored apixaban (RR, 0.45; 95% CI, 0.27, 0.75) only. Rivaroxaban (RR, 0.45; 95% CI, 0.27, 0,77) and apixaban (RR, 0.38; 95% CI, 0.16, 0.90) produced significantly lower frequencies of symptomatic DVT. The incidence of major VTE favored rivaroxaban (RR, 0.44; 95% CI, 0.25, 0.81), only. Bleeding risk was similar for all NACs, except fondaparinux (RR, 1.27; 95% CI, 1.04, 1.55), which exhibited a significantly higher any-bleeding risk compared with enoxaparin, and apixaban (RR, 0.88; 95% CI, 0.79, 0.99), which was associated with a reduced risk of any bleeding. Alanine amino transferase was significantly lower with 220 mg of dabigatran, (RR, 0.67; 95% CI, 0.79, 0.99) than with enoxaparin.

CONCLUSIONS

NACs can be considered alternatives to conventional thromboprophylaxis regimens in patients undergoing elective major orthopedic surgery, depending on clinical characteristics and cost-effectiveness. The knowledge of some differences concerning efficacy or safety profile, pointed out in this systematic review, along with the respective limitations, may be useful in clinical practice.

[Thromboprophylaxis with enoxaparin for total knee replacement: an observational, retrospective and multicentre study comparing starting the treatment before and after the operation]

OBJECTIVE

The low molecular weight heparins are the first option for the prophylaxis of venous thromboembolic disease in major orthopaedic surgery. The time of starting their administration is controversial. The aim of this study was to evaluate the efficacy and safety of enoxaparin in patients subjected to total knee replacement comparing the starting of it before and after the surgery.

METHODS

An observational, retrospective and multicentre study of normal clinical practice to determine the incidence of symptomatic deep venous thrombosis and/or pulmonary thromboembolism in total knee replacement surgery. Thromboprophylaxis was normal practice in each centre. Patients were included if they received the first dose of 40 mg/24 h of enoxaparin either 12 h (± 2 h) before the surgery (G-PRE) or between 6 and 12 hours after the surgery (G-POST). The main safety objective was haemorrhage. A multivariate logistic regression analysis was performed to determine the real influence of each variable.

RESULTS

Data was collected from 2014 patients, of whom 1440 were included for the analysis of efficacy (782/1440, 54% of the G-PRE and 658/1440, 46% of the G-POST). The mean incidence of symptomatic thrombotic events was 1.67% (24/1440). The incidence of deep venous thrombosis in the G-PRE was 1.15% compared to 1.22% in the G-POST (P=.569 after multivariate analysis) and the incidence of pulmonary thromboembolism was 0.51 compared to 0.76%, respectively (P=.582 after multivariate analysis). A total of 1422 patients were included for the safety analysis. There was significant bleeding in 59/788 of the G-PRE and in 35/634 of the G-POST (7.49% compared to 5.52%, respectively, P=.138).

CONCLUSIONS

These results suggest that thromboprophylaxis with enoxaparin (40 mg/24 h sc) in patients subjected to total knee replacement surgery has a similar safety and effective profile when it is given 12 hours before the surgery or between 6 and 12 hours afterwards.

Differential effects of fondaparinux and bemiparin on angiogenic and vasculogenesis-like processes

INTRODUCTION

Conventional therapy for venous thromboembolism or acute coronary syndrome involves the administration of glycoanticoagulants (heparins) or oligosaccharides (fondaparinux). We evaluated the effects of such drugs on angiogenesis and vasculogenesis-like models.

MATERIALS AND METHODS

Human umbilical vein endothelial cells or human endothelial progenitor cells were treated with bemiparin, fondaparinux or unfractionated heparin, at concentrations reflecting the doses used in clinical practice. After 24h, cell viability, proliferation, tubule formation and angiogenic molecular mechanisms, such as activation of the serine/threonine kinase AKT, were assessed. In vivo angiogenesis was studied using a Matrigel sponge assay in mice.

RESULTS

Bemiparin gave a significant decrease of in vitro angiogenesis as shown by the reduction of endothelial cell tubule network, while both fondaparinux and unfractionated heparin did not show any significant effect. In assays of Matrigel sponge invasion in mice, unfractionated heparin was able to stimulate angiogenesis and, conversely, bemiparin inhibited angiogenesis. Furthermore, both bemiparin and fondaparinux caused a significant reduction in an in vitro vasculogenesis-like model, as demonstrated by the decrease of tubule network after co-seeding of endothelial progenitor cells and human umbilical vein endothelial cells. In addition, unfractionated heparin but not bemiparin was able to increase AKT phosphorylation.

CONCLUSIONS

In in vitro experiments, bemiparin was the only drug to show an anti-angiogenic and vasculogenic-like effect, unfractionated heparin showed only a trend to increase in angiogenesis assay and fondaparinux affected only the vasculogenesis-like model. Notably, the in vivo experiments corroborated these data. Such results are important for the choice of a patient-tailored therapy.

Meta-analysis of cause of death following total joint replacement using different thromboprophylaxis regimens

We performed a meta-analysis of modern total joint replacement (TJR) to determine the post-operative mortality and the cause of death using different thromboprophylactic regimens as follows: 1) no routine chemothromboprophylaxis (NRC); 2) Potent anticoagulation (PA) (unfractionated or low-molecular-weight heparin, ximelagatran, fondaparinux or rivaroxaban); 3) Potent anticoagulation combined (PAC) with regional anaesthesia and/or pneumatic compression devices (PCDs); 4) Warfarin (W); 5) Warfarin combined (WAC) with regional anaesthesia and/or PCD; and 6) Multimodal (MM) prophylaxis, including regional anaesthesia, PCDs and aspirin in low-risk patients. Cause of death was classified as autopsy proven, clinically certain or unknown. Deaths were grouped into cardiopulmonary excluding pulmonary embolism (PE), PE, bleeding-related, gastrointestinal, central nervous system, and others (miscellaneous). Meta-analysis based on fixed effects or random effects models was used for pooling incidence data. In all, 70 studies were included (99 441 patients; 373 deaths). The mortality was lowest in the MM (0.2%) and WC (0.2%) groups. The most frequent cause of death was cardiopulmonary (47.9%), followed by PE (25.4%) and bleeding (8.9%). The proportion of deaths due to PE was not significantly affected by the thromboprophylaxis regimen (PA, 35.5%; PAC, 28%; MM, 23.2%; and NRC, 16.3%). Fatal bleeding was higher in groups relying on the use of anticoagulation (W, 33.8%; PA, 9.4%; PAC, 10.8%) but the differences were not statistically significant. Our study demonstrated that the routine use of PA does not reduce the overall mortality or the proportion of deaths due to PE.

The Efficacy and Safety of Pharmacological Prophylaxis of Venous Thromboembolism Following Elective Knee or Hip Replacement

The present systematic review was conducted to assess the efficacy and safety of apixaban versus other anticoagulants, for the prevention of venous thromboembolism (VTE) following total hip replacement (THR) and total knee replacement (TKR) surgery. Electronic databases were interrogated to identify relevant randomized controlled trials. A series of direct/indirect comparisons and a network meta-analysis were conducted. Indirect comparisons found that the odds ratio of “all VTE and all-cause death” were significantly higher for dabigatran than for apixaban in patients with THR (odds ratio [OR], 2.51; 95% confidence interval [CI], 1.50-4.21) and TKR (OR, 1.72; 95% CI, 1.22-2.42). Rivaroxaban showed similar efficacy to apixaban in patients with THR and TKR (OR, 0.69; 95% CI, 0.38-1.25 and OR, 0.83; 95% CI, 0.57-1.19, respectively). No significant differences were observed in bleeding outcomes between treatments. The novel anticoagulants apixaban, rivaroxaban, and dabigatran demonstrated similar or improved efficacy and similar safety compared with current therapies in this indication.

[Incidence and distribution of venous thrombosis of the lower limbs diagnosed by duplex ultrasonography after total hip or total knee arthroplasty, and hip fracture surgery. Results from 5981 exams and 2123 cases of venous thrombosis over 10 years]

AIM

To determine the incidence and distribution of lower limb venous thrombosis diagnosed by duplex ultrasonography, including calf exploration, after total hip or knee replacement or hip fracture, and to compare them with the venographic results reported by recent randomized control trials testing new antithrombotic drugs.

PATIENTS AND METHODS

From January 2001 to December 2009, 30,510 standardized report forms incremented a database from which files corresponding to major orthopaedic surgery were selected: 1652 after total hip replacement (THR), 1440 after total knee replacement (TKR) and 2889 after hip fracture (HF). Base-line characteristics, incidence and anatomic distribution of venous thrombosis were analysed in the three populations.

RESULTS

Systematic screening was applied for 95.1% of the exams (n=5689). Incidence of total and proximal venous thrombosis was, respectively, 27.8% (n=460) and 2.8% (n=46) for THR, 32.5% (n=939) and 4.4% (n=126) for HF, and 50.3% (n=724) and 3.8% (n=55) for TKR. Venous thrombosis was distal in 89.3% (n=1896). More than half (n=1014) of distal venous thromboses were strictly muscular soleal locations. Ilio-caval thrombosis incidence was 0.18% (n=11), and superficial venous thrombosis incidence was 1.5% (n=89).

CONCLUSION

This study shows that incidence and distribution of venous thromboses diagnosed with a complete and standardized duplex ultrasonographic screening are very close to the rates published with venographic screening in recent trials.

Novos anticoagulantes para a profilaxia do tromboembolismo venoso em cirurgias ortopédicas de grande porte

Após cerca de 50 anos de experiência com a heparina e antagonistas da vitamina K (AVK), pesquisas e estudos com novos anticoagulantes vêm evoluindo de forma crescente nos últimos anos. Embora consagrados pelo uso, os anticoagulantes tradicionais têm limitações importantes em termos de controle laboratorial, complicações, efeitos colaterais, interações com medicamentos e dieta. A heparina não fracionada (HNF) tem interação com proteínas plasmáticas e parede vascular, pode desencadear trombocitopenia induzida pela heparina (TIH), só pode ser administrada por via parenteral, exige controle laboratorial pelo teste da tromboplastina parcial ativada (TTPa), pode provocar osteoporose e alopecia quando usada por períodos prolongados e sua produção tem origem biológica. A AVK tem a vantagem de poder ser ministrada por via oral, mas o controle (feito pela razão normatizada internacional) pode ser difícil em alguns casos, já que tem início de ação demorado, janela terapêutica estreita, interação com dieta e grande número de medicamentos, pode provocar necrose de pele em portadores de deficiência de antitrombina e de proteínas C e S, e pode induzir alterações fetais quando usada na gravidez. Na década de 1980, surgiram as heparinas de baixo peso molecular, que foram uma evolução da heparina não fracionada, pois apresentaram maior biodisponibilidade, dosagem por peso corporal, sem necessidade de controle laboratorial, administração por via subcutânea, menor risco de trombocitopenia induzida pela heparina, e eficácia e segurança similares à heparina não fracionada. Na última década surgiram, então, uma série de novos anticoagulantes no mercado, os quais têm apresentado resultados promissores em várias situações de profilaxia e tratamento do tromboembolismo venoso. Nesta revisão, são apresentados as novas heparinas de baixo peso molecular, as heparinas de ultrabaixo peso molecular, os pentassacarídeos, os novos inibidores diretos do fator Xa e inibidores do fator IIa.

New challenges for a second-generation low-molecular-weight heparin: focus on bemiparin

Bemiparin is a second-generation low-molecular-weight heparin (LMWH) that has the lowest molecular weight, the longest half-life and the highest anti-Factor Xa/anti-Factor IIa activity ratio. The safety and efficacy of bemiparin has been demonstrated in several studies and currently it is licensed for the treatment and prophylaxis of venous thromboembolism (VTE), as well as for the prevention of clotting in the extracorporeal circuit during hemodialysis. Multicenter pharmacoeconomic studies carried out in the Spanish National Health system indicate that bemiparin is more cost effective than enoxaparin for the prevention of VTE in total knee replacement. Interestingly, recent results suggest that bemiparin could be useful as an adjuvant treatment in the management of lower-extremity diabetic ulcers. Since international guidelines recommend LMWHs for initial and continuous anticoagulant treatment in cancer patients with VTE, as well as for its prevention, results from ongoing trials could be critical to establish the potential of bemiparin in oncological patients. Finally, the pharmacokinetics of two oral bemiparin formulations are currently being analyzed in a Phase I trial.

Overview of current venous thromboembolism protocols in hip reconstruction

Venous thromboembolic disease continues to be a serious complication of total-hip arthroplasty. The use of anticoagulant drugs for preventing this complication has repeatedly been proven to be useful. This article reviews the current evidence-based recommendations for anticoagulant prophylaxis after total-hip arthroplasty and provides insight into the current areas of active research and controversy.

Prevention and treatment of venous thromboembolism with low-molecular-weight heparins: Clinical implications of the recent European guidelines

Venous thromboembolism (VTE) is an important cause of avoidable morbidity and mortality. However, routine prophylaxis for at-risk patients is underused. Recent guidelines issued by an international consensus group, including the International Union of Angiology (IUA), recommend use of low-molecular-weight heparins (LMWHs) for the treatment of acute VTE and prevention of recurrence, and for prophylaxis in surgical and medical patients. This review highlights current inadequacies in the provision of thromboprophylaxis, and considers the clinical implications of the European guidelines on the prevention and treatment of VTE.

Bemiparin: second-generation, low-molecular-weight heparin for treatment and prophylaxis of venous thromboembolism

Low-molecular-weight heparins (LMWHs) form a heterogeneous group of compounds that exhibit an extended range of pharmacodynamic profiles and, potentially, different anti-thrombotic properties. Bemiparin has the lowest MW (3600 Da), the longest half-life (5.3 h) and the highest anti-FXa/anti-FIIa activity ratio (8:1) of any second-generation LMWH. The safety and efficacy of bemiparin has been demonstrated in several studies and it is currently licensed for treatment and prophylaxis of venous thromboembolism (VTE), as well as for the prevention of clotting in the extracorporeal circuit during hemodialysis. In particular, bemiparin is the only LMWH licensed in Europe for starting thromboprophylaxis after either general or orthopedic surgery. Results from multicenter pharmacoeconomic studies in the Spanish Health Care System indicate that bemiparin is more cost effective than enoxaparin for the prevention of VTE in total knee replacement and may be a safe, cost-saving alternative to unfractionated heparin in the short-term treatment of VTE, and a safe cost-neutral alternative to oral anticoagulant therapy in long-term treatment. In the near future, information from ongoing clinical trials could be key to establishing the potential of bemiparin in different clinical settings.

Evaluation of the Effectiveness and Safety of Bemiparin in a Large Population of Orthopedic Patients in a Normal Clinical Practice

The authors conducted a prospective, open, multicenter, observational study to audit the utilization patterns of bemiparin in orthopedic patients in daily clinical practice. They analyzed rates of documented symptomatic venous thromboembolism (VTE) (deep vein thrombosis and pulmonary embolism) confirmed by objective methods, major bleeding, death, thrombocytopenia, and other adverse events. It was also intended to analyze the influence of concomitant factors (bemiparin dose, concomitant medications, age, and obesity) on VTE and bleeding rates. A total of 7959 patients were included and received bemiparin for 28 days (median). Bemiparin 3500 IU/d was used in 84.9% of patients, whereas bemiparin 2500 IU/d was administered to 15.1% of patients. Reason for prophylaxis (number of cases [%]) included cast immobilization of the leg (2052 [25.8%]), knee replacement (1082 [13.6%]), hip replacement (876 [11.0%]), hip fracture surgery (437 [5.5%]), other lower limb surgery (1569 [19.7%]), knee arthroscopy (769 [9.7%]), and spine surgery (231 [2.9%]). A total of 943 patients with insufficient data on reason for prophylaxis and 560 patients with no outcome assessment were excluded from the analysis of clinical outcomes. Among 6456 assessable patients, the authors found a low rate of documented symptomatic VTE (0.91%), major bleeding (0.17%), deaths (0.37%), and mild to moderate thrombocytopenia (0.51%). None of the major bleedings was fatal or occurred in a critical organ. There were 3 deaths in which fatal pulmonary embolism (PE) could not be ruled out. There were no cases of severe type-II thrombocytopenia. VTE rates were not increased in obese patients, and major bleeding rates were not increased in elderly patients or in patients taking nonsteroidal anti-inflammatory drugs. In conclusion, bemiparin prophylaxis, given for 3 to 4 weeks in cast immobilization of the leg and other orthopedic procedures, was associated with low rates of VTE, bleeding, and other adverse events in normal clinical practice.

A prospective observational study on the effectiveness and safety of bemiparin, first dose administered 6 h after knee or hip replacement surgery

INTRODUCTION

Bemiparin has shown to be effective and safe in clinical trials in total knee or hip replacement.

MATERIALS AND METHODS

We conducted a prospective, open, multicentre, uncontrolled study to audit the utilisation patterns of bemiparin 3,500 IU/day, first dose administered 6 h after surgery, in 1,009 patients undergoing total hip or knee replacement surgery in standard clinical practice. We analysed rates of documented symptomatic venous thromboembolism (VTE) [deep-vein thrombosis (DVT) and pulmonary embolism (PE)] confirmed by objective methods, major bleeding, death, thrombocytopaenia and other adverse events up to 6 weeks.

RESULTS

Rate of documented symptomatic DVT was 0.3% (95% CI, 0.1-0.9%). No cases of documented PE were reported. There were 14 (1.4%) major bleedings (95% CI, 0.8-2.3%). Neuraxial anaesthesia was used in 937 (92.9%) patients. There were no cases of spinal haematoma, fatal bleeding or bleeding in critical organs. There were 6 (0.6%) cases of mild thrombocytopaenia, which did not require treatment discontinuation. No cases of severe type II heparin-induced thrombocytopaenia were observed. There were no deaths during bemiparin prophylaxis. The median length of hospitalisation was 9 days and 92.5% of patients continued prophylaxis post-hospitalisation for a total median time of 38 days. There were no thromboembolic or bleeding complications during post-hospitalisation prophylaxis. Postoperative start of prophylaxis with bemiparin permitted that 29.3% of patients could be admitted to hospital the same day of the intervention.

CONCLUSION

Bemiparin prophylaxis, started 6 h after surgery and given for 5-6 weeks after total hip or knee replacement, was associated with low rates of VTE, major bleeding and other adverse events in normal clinical practice. Bemiparin thromboprophylaxis started 6 h after surgery makes neuraxial anaesthesia/analgesia procedures easier, without compromising efficacy.

Effect of the anti-factor Xa and anti-factor IIa activities of low-molecular-weight heparins upon the phases of thrombin generation

BACKGROUND

Low-molecular-weight heparins (LMWHs), derived from unfractionated heparin (UFH) by different depolymerization procedures, vary in both their relative abilities to enhance the inhibition of FXa (anti-FXa) and thrombin (anti-FIIa), and in their physicochemical properties.

OBJECTIVE

We aimed to profile the inhibition of thrombin generation induced by bemiparin, enoxaparin, nadroparin, dalteparin and tinzaparin in platelet-rich plasma (PRP), and to compare them with UFH and fondaparinux (a synthetic pentasaccharide that specifically enhances FXa inhibition).

METHODS

Different LMWHs, UFH or fondaparinux were added to normal PRP. Thereafter, tissue factor-triggered thrombin generation was assessed using the Thrombogram-Thrombinoscope assay.

RESULTS

At equivalent anti-FIIa activity concentrations, LMWHs and UFH exhibited similar inhibitory effects upon thrombin generation. However, when used at equivalent anti-FXa activity concentrations, tinzaparin was significantly more active than the other LMWHs at inhibiting thrombin generation, and had similar activity to that of UFH. Enoxaparin, nadroparin and dalteparin all showed similar inhibitory activities. In these experiments, bemiparin exhibited the lowest inhibitory effect on thrombin generation of all the LMWHs. At 0.1 microg mL(-1) (0.093 anti-FXa IU mL(-1)), fondaparinux inhibited the rate of thrombin generation by 50%. A 7-fold higher concentration of fondaparinux was required to inhibit the endogenous thrombin potential by 50%.

CONCLUSIONS

LMWHs have a variable inhibitory effect on thrombin generation in vitro when compared by anti-FXa activity, but are similar when compared by their anti-FIIa activities. The rate of thrombin generation during the propagation phase, rather than the endogenous thrombin potential, is more sensitive to the anticoagulant activity of fondaparinux and the polysaccharide chains of LMWHs possessing only anti-FXa activity.

Low-molecular-weight heparin as bridging therapy during interruption of oral anticoagulation in patients undergoing colonoscopy or gastroscopy

Nowadays, most patients under oral anticoagulant therapy (OAT) require invasive procedures such as colonoscopy (CC) or gastroscopy (GC). The goals of the management of OAT are to minimise the risk of thromboembolism and bleeding. We have performed the first prospective, observational study to evaluate these parameters using fixed-dose high-risk thromboprophylactic therapy with sodic bemiparin (Hibor) as bridging therapy. From January 2004 to January 2005, patients under OAT were included. Periprocedure prophylaxis consisted of: Acenocumarol patients: Day -3: withdrawal acenocumarol. Days -2,-1,0: Hibor 3500 UI/d sc and days +1,+2,+3: Hibor 3500 U/I + acenocumarol. And day +5: acenocumarol only. Warfarin patients: Days -5,-4: withdrawal warfarin, -3,-2,-1, 0; Hibor 3500 UI/day sc, days +1,+2,+3,+4: Hibor 3500 UI/day sc and warfarin and day +5; warfarin only. Thromboembolic complications and bleeding were recorded in a 3 month follow-up. We included 100 consecutive patients in the intention-to-treat group. The remaining 98 patients were 50 women and 48 men. Mean age of women was 71.1 (range: 46-87) years and 70.7 (range: 39-86) years in men. Eighty-three took acenocumarol, and 15 warfarin. Thirty-two gastroscopies and 61 colonoscopies were performed and in five patients both were performed. No thromboembolic and bleeding complications related to bemiparin were observed in the 103 endoscopies. Two patients developed pruritus at the punction site. Fixed-dose high-risk thromboprophilactic therapy with bemiparin (Hibor) is safe and effective as a bridging therapy in patients under OAT who require GC or CC.

Prevention of venous thromboembolism: the Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy

This article discusses the prevention of venous thromboembolism (VTE) and is part of the Seventh American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this chapter are the following. We recommend against the use of aspirin alone as thromboprophylaxis for any patient group (Grade 1A). For moderate-risk general surgery patients, we recommend prophylaxis with low-dose unfractionated heparin (LDUH) (5,000 U bid) or low-molecular-weight heparin (LMWH) [< or = 3,400 U once daily] (both Grade 1A). For higher risk general surgery patients, we recommend thromboprophylaxis with LDUH (5,000 U tid) or LMWH (> 3,400 U daily) [both Grade 1A]. For high-risk general surgery patients with multiple risk factors, we recommend combining pharmacologic methods (LDUH three times daily or LMWH, > 3,400 U daily) with the use of graduated compression stockings and/or intermittent pneumatic compression devices (Grade 1C+). We recommend that thromboprophylaxis be used in all patients undergoing major gynecologic surgery (Grade 1A) or major, open urologic procedures, and we recommend prophylaxis with LDUH two times or three times daily (Grade 1A). For patients undergoing elective total hip or knee arthroplasty, we recommend one of the following three anticoagulant agents: LMWH, fondaparinux, or adjusted-dose vitamin K antagonist (VKA) [international normalized ratio (INR) target, 2.5; range, 2.0 to 3.0] (all Grade 1A). For patients undergoing hip fracture surgery (HFS), we recommend the routine use of fondaparinux (Grade 1A), LMWH (Grade 1C+), VKA (target INR, 2.5; range, 2.0 to 3.0) [Grade 2B], or LDUH (Grade 1B). We recommend that patients undergoing hip or knee arthroplasty, or HFS receive thromboprophylaxis for at least 10 days (Grade 1A). We recommend that all trauma patients with at least one risk factor for VTE receive thromboprophylaxis (Grade 1A). In acutely ill medical patients who have been admitted to the hospital with congestive heart failure or severe respiratory disease, or who are confined to bed and have one or more additional risk factors, we recommend prophylaxis with LDUH (Grade 1A) or LMWH (Grade 1A). We recommend, on admission to the intensive care unit, all patients be assessed for their risk of VTE. Accordingly, most patients should receive thromboprophylaxis (Grade 1A).

Bemiparin

Bemiparin (bemiparin sodium; Hibor, Ivor, Zibor, Badyket) is a low molecular weight heparin (LMWH) with a lower mean molecular weight (3600 D) and a higher anti-Xa/IIa ratio (8:1) than other LMWHs. Bemiparin was effective as thromboprophylaxis in surgical patients in well controlled clinical trials. No cases of venous thromboembolism (VTE) were reported in low- to moderate-risk patients receiving prophylaxis with bemiparin 2500 anti-Xa IU/day for 7 days or unfractionated heparin (UFH) 5000 anti-Xa IU twice daily for 7 days. In high-risk patients, bemiparin 3500 anti-Xa IU/day for > or =8 days was more effective than UFH 5000 anti-Xa IU twice daily for > or =8 days in the prevention of VTE in patients undergoing total hip replacement. Postoperative bemiparin 3500 anti-Xa IU/day for 10 days was as effective as enoxaparin 4000 anti-Xa IU/day for 10 days commenced 12 hours before surgery in high-risk patients undergoing total knee replacement. As a short-term treatment for acute established deep vein thrombosis (DVT), bemiparin 5000-10 000 anti-Xa IU/day (dependent on bodyweight) for 7 or 10 days was more effective than intravenous UFH (5000 anti-Xa IU bolus followed by 30,000 or 40,000 anti-Xa IU/day for 7 days) in reducing thrombus size from baseline. Bemiparin 3500 anti-Xa IU/day was also as effective as oral warfarin (10 mg/day for the first 3 days, then adjusted to achieve an international normalised ratio between 2 and 3) for the long-term (12 weeks) treatment of DVT, although data are limited. Subcutaneous bemiparin was generally well tolerated. The most commonly reported adverse events in clinical trials were postoperative bleeding complications (similar incidence to that with UFH or enoxaparin in high-risk patients, lower incidence in low- to moderate-risk patients).

CONCLUSIONS

Bemiparin is a new LMWH which has shown efficacy in a small number of well controlled trials in the prevention of postoperative VTE in low- to moderate- and high-risk patients and in the treatment of established DVT. It can be initiated pre- or post-operatively, whereas recommendations for other LMWHs in Europe primarily involve preoperative initiation. Additional comparative studies would be beneficial in determining the overall place of bemiparin, particularly with respect to the relative incidence of bleeding complications. In the meantime, available data suggest that bemiparin is an effective and useful addition to the available range of LMWHs for the prevention of VTE and treatment of DVT.