A common standard is inappropriate for determining the potency of ultra low molecular weight heparins such as semuloparin and bemiparin

Recent advances in anticoagulant drug delivery

INTRODUCTION

Anticoagulants have been prescribed to patients to prevent deep vein thrombosis or pulmonary embolism. However, because of several problems in anticoagulant therapy, much attention has been directed at developing an ideal anticoagulant, and numerous attempts have been made to develop new anticoagulant delivery systems in recent years.

AREAS COVERED

This review discusses the challenges associated with the recent development of anticoagulants and their delivery systems. Various delivery methods have been developed to improve the use of anticoagulants. Recent advances in anticoagulant delivery and antidote development are also discussed in the context of their current progression states.

EXPERT OPINION

There have been many different approaches to developing the delivery system of anticoagulants. One approach has been to expand the use of new oral agents and develop their antidotes. Reducing the size of heparins to use smaller heparins for delivery, and developing oral or topical heparins are also some of the approaches used. Various physical formulations or chemical modifications are other ways that have enhanced the therapeutic potential of anticoagulant agents. On the whole, recent advances have contributed to increasing the efficacy and safety of anticoagulant clinically and have benefited the field of anticoagulant delivery.

Bemiparin for thromboprophylaxis after benign gynecologic surgery: a randomized clinical trial

BACKGROUND

Venous thromboembolism (VTE) is the leading cause of mortality and morbidity in women following gynecologic surgery.

OBJECTIVES

To determine the efficacy of a second-generation low molecular weight heparin (bemiparin) for thromboprophylaxis after benign gynecologic surgery.

METHODS

We performed a single-blind randomized controlled trial including women in the moderate-risk, high-risk and highest-risk groups for developing VTE after benign gynecologic surgery. Participants were randomized at a 1 : 1 ratio into parallel groups to receive either seven daily doses of 3500 IU of subcutaneous bemiparin or to a non-intervention group receiving standard rehydration and advice on ambulation. Participants were followed up for 7 days and 30 days postoperatively for symptomatic VTE, which was confirmed by compression Doppler ultrasound, magnetic resonance imaging, or computed tomographic pulmonary angiography, according to the type of VTE.

RESULTS

In total, 387 participants were randomized to the bemiparin group and 387 to the non-intervention group. The incidence of symptomatic VTE (deep vein thrombosis and pulmonary embolism) events was lower (0/377) in participants who received bemiparin than in those who received no pharmacologic intervention (12/380, 3.2%; 95% confidence interval [CI] 0.002-0.6). Logistic regression analysis showed significant associations between VTE and immobility (odds ratio [OR] 7.1; 95% CI 1.3-36.2), varicose veins (OR 16.8; 95% CI 3.1-76.2), and thrombophilia (OR 39.3; 95% CI 1.5-1006.7). There were no major bleeding events or side effects related to the use of bemiparin.

CONCLUSIONS

Bemiparin was an effective thromboprophylactic agent for preventing venous thrombosis after benign gynecologic surgery.

Evolution of heparin anticoagulants to ultra-low-molecular-weight heparins: a review of pharmacologic and clinical differences and applications in patients with cancer

The burden of venous thromboembolism (VTE) is high in patients with cancer, particularly those with metastatic disease and those receiving chemotherapy. The use of heparin and heparin derivatives should be considered for primary prevention of VTE in hospitalized patients with cancer and in patients undergoing cancer surgery. Preliminary evidence also suggests that heparins may have direct anticancer benefits owing to effects on tumor growth, angiogenesis, and metastasis. Despite the potential benefits of heparin-derived anticoagulants, many at-risk patients do not receive adequate thromboprophylaxis. The evolution of unfractionated heparin to low-molecular-weight and ultra-low-molecular-weight heparins has provided practitioners with alternatives for VTE prevention in cancer, although these alternatives present challenges related to clinically relevant pharmacologic differences between agents. In this review, we present results from our review of the medical literature focusing on the use of the heparin-derived anticoagulants in prospective interventional studies of primary thromboprophylaxis in patients with cancer in surgical, hospitalized, and ambulatory settings.

Anticoagulant and Antithrombotic Actions of AVE5026, an Enriched Anti-Xa Hemisynthetic Ultra-Low-Molecular-Weight Heparin

INTRODUCTION

AVE5026 represents a new generation of ultra-low-molecular-weight heparin (LMWH) with high anti-Xa and low anti-IIa activities (anti Xa-IIa ratio >30). In addition, AVE5026 exhibits a relatively higher proportion of AT components.

MATERIALS AND METHODS

The anticoagulant, antiplatelet, antithrombotic, and bleeding effects of AVE5026 in comparison to other heparins were investigated in this study.

RESULTS

AVE5026 demonstrated weak effects in the global clotting assays; however, in the amidolytic anti-Xa assay, AVE5026 produced strong inhibitory effects. AVE5026 showed no cross-reactivity with the heparin-induced thrombocytopenia antibodies in the platelet aggregation system. AVE5026 produced a dose-dependent antithrombotic response after intravenous (IV) and subcutaneous (SC) administration in thrombosis models. The relative bleeding effects of AVE5026 in a rat tail bleeding and rabbit blood loss model were negligible after both IV and SC administration.

CONCLUSIONS

This superior safety efficacy index in animal models in comparison with other LMWH may translate into improved antithrombotic efficacy with decreased bleeding risk.