Clinicians are aware of the importance of thromboprophylaxis, and that the application of measures to prevent venous thromboembolism (VTE) occurrence in hospitalized patients must be improved. To enhance clinician execution of appropriate steps to reduce the risk of inpatient VTE, a performance improvement (PI) continuing medical education (CME) initiative consisting of 3 independent tracks for hospitalized patients-patients who are medically ill, patients receiving oncology treatment, and patients undergoing major orthopedic surgery-was designed and implemented. After a baseline chart review of select evidenced-based performance measures for VTE risk stratification and prevention, participants identified ≥ 1 area of personal improvement. Participants then engaged in a period of self-improvement and reassessed their performance with a second chart review. After participating in the PI CME activity, clinician participants in the medically ill track increased their documentation of VTE risk assessments upon patient admission from baseline (56% vs 93%, n = 250; P < 0.001) and their prescription of low-molecular-weight heparin, low-dose unfractionated heparin, or fondaparinux (72% vs 88%, n = 250; P < 0.001). Orthopedic-track participants were significantly more likely to prescribe 15 to 35 days of VTE prophylaxis after total hip arthroplasty or hip fracture surgery upon patient discharge compared with baseline (51%, n = 123 vs 61%, n = 107; P < 0.001). Oncology-track participants demonstrated a nonsignificant trend for assessing and documenting bleeding risk after participation in the PI CME activity (56% vs 68%, n = 80; P = 0.143). Improvements in evidence-based strategies to reduce the risk of inpatient VTE were associated with PI CME participation. Although areas for improvement remain, increased participant identification and use of prophylactic measures can reduce the risk of VTE in hospitalized patients.

Venous thromboembolism (VTE), encompassing deep vein thrombosis and pulmonary embolism, represents a major cause of morbidity and mortality in patients with cancer. Low molecular weight heparins are the preferred option for anticoagulation in cancer patients according to current clinical practice guidelines. Fondaparinux may also have a place in prevention of VTE in hospitalized cancer patients with additional risk factors and for initial treatment of VTE. Although low molecular weight heparins and fondaparinux are effective and safe, they require daily subcutaneous administration, which may be problematic for many patients, particularly if long-term treatment is needed. Studying anticoagulant therapy in oncology patients is challenging because this patient group has an increased risk of VTE and bleeding during anticoagulant therapy compared with the population without cancer. Risk factors for increased VTE and bleeding risk in these patients include concomitant treatments (surgery, chemotherapy, placement of central venous catheters, radiotherapy, hormonal therapy, angiogenesis inhibitors, antiplatelet drugs), supportive therapies (ie, steroids, blood transfusion, white blood cell growth factors, and erythropoiesis-stimulating agents), and tumor-related factors (local vessel damage and invasion, abnormalities in platelet function, and number). New anticoagulants in development for prophylaxis and treatment of VTE include parenteral compounds for once-daily administration (ie, semuloparin) or once-weekly dosing (ie, idraparinux and idrabiotaparinux), as well as orally active compounds (ie, dabigatran, rivaroxaban, apixaban, edoxaban, betrixaban). In the present review, we discuss the pharmacology of the new anticoagulants, the results of clinical trials testing these new compounds in VTE, with special emphasis on studies that included cancer patients, and their potential advantages and drawbacks compared with existing therapies.

INTRODUCTION:

Oral factor Xa (FXa) inhibitors are a novel class of anticoagulants that, unlike heparins, are expected to demonstrate antithrombotic effects independent of plasma antithrombin (AT) concentrations. We utilized heterozygous AT-deficient (AT+/-) mice to determine the impact of AT deficiency on anticoagulant and antithrombotic effects of edoxaban, a direct FXa inhibitor, and compared with heparins (fondaparinux, enoxaparin, and unfractionated heparin [UHF]).

MATERIALS AND METHODS:

The effects of edoxaban and heparins on in vitro prothrombin time and activated partial thromboplastin time were measured in plasma obtained from wild type (AT+/+) and AT+/- male mice. To assess the antithrombotic effects of these anticoagulants in vivo, venous thrombosis was induced in the inferior vena cava by FeCl3 treatment. Potency ratios of antithrombotic effects in AT+/- compared with AT+/+ mice were analyzed by a parallel line assay.

RESULTS:

In vitro studies demonstrated that the clotting-time prolongation effects of edoxaban were not affected by heterozygous AT deficiency whereas those of AT-dependent anticoagulants were attenuated. In AT+/- mice, the antithrombotic effects of AT-dependent anticoagulants were less potent than those in AT+/+ mice. In contrast, edoxaban was equipotent in preventing thrombus formation in both wild-type and AT-deficient mice. The attenuated antithrombotic effects of fondaparinux, enoxaparin, and UFH in AT-deficient mice were restored by AT supplementation. Edoxaban exerts a comparable antithrombotic effect even in mice with low plasma AT antigen and activity to that in wild-type mice.

CONCLUSION:

Edoxaban may potentially be prioritized over AT-dependent anticoagulants in patients with lower plasma AT concentration.

The American College of Chest Physicians provides recommendations for the use of anticoagulant medications for several indications that are important in the primary care setting. Warfarin, a vitamin K antagonist, is recommended for the treatment of venous thromboembolism and for the prevention of stroke in persons with atrial fibrillation, atrial flutter, or valvular heart disease. When warfarin therapy is initiated for venous thromboembolism, it should be given the first day, along with a heparin product or fondaparinux. The heparin product or fondaparinux should be continued for at least five days and until the patient's international normalized ratio is at least 2.0 for two consecutive days. The international normalized ratio goal and duration of treatment with warfarin vary depending on indication and risk. Warfarin therapy should be stopped five days before major surgery and restarted 12 to 24 hours postoperatively. Bridging with low-molecular-weight heparin or other agents is based on balancing the risk of thromboembolism with the risk of bleeding. Increasingly, self-testing is an option for selected patients on warfarin therapy. The ninth edition of the American College of Chest Physicians guidelines, published in 2012, includes a discussion of anticoagulants that have gained approval from the U.S. Food and Drug Administration since publication of the eighth edition in 2008. Dabigatran and apixaban are indicated for the prevention of systemic embolism and stroke in persons with nonvalvular atrial fibrillation. Rivaroxaban is indicated for the prevention of deep venous thrombosis in patients undergoing knee or hip replacement surgery, for treatment of deep venous thrombosis and pulmonary embolism, for reducing the risk of recurrent deep venous thrombosis and pulmonary embolism after initial treatment, and for prevention of systemic embolism in patients with nonvalvular atrial fibrillation.

Patients with deep venous thrombosis are at a short-term risk of symptomatic or even life-threatening pulmonary embolism, and a long-term risk of post-thrombotic syndrome, characterised by lower-limb pain, varicose veins, oedema, and sometimes skin ulcers. What is the best choice of initial antithrombotic therapy following deep venous thrombosis or pulmonary embolism, in terms of mortality and short-term and long-term complications? How do the harm-benefit balances of the different options compare? To answer these questions, we reviewed the available literature using the standard Prescrire methodology. Unfractionated heparin has documented efficacy in reducing mortality and recurrent thromboembolic events in patients with pulmonary embolism or symptomatic proximal (above-knee) deep venous thrombosis. The authors of a systematic review selected 23 trials of low-molecular-weight heparin (LMWH) versus adjusted-dose unfractionated heparin in a total of 9587 patients. Deaths, recurrences and major bleeds were less frequent with LMWH than with unfractionated heparin. The results of other meta-analyses are similar, but all are undermined by a probable publication bias and methodological flaws. Compared to unfractionated heparin, LMWHs have the advantage of fixed-dose administration, once or twice daily, by subcutaneous injection. All available LMWHs seem to have similar efficacy. Those with the longest experience of use are enoxaparin, dalteparin and nadroparin. The harm-benefit balances of fondaparinux and rivaroxaban do not appear more favourable than that of an LMWH followed by an adjusted-dose vitamin K antagonist. A meta-analysis included 12 trials comparing thrombolysis with anticoagulation alone in 700 patients with deep venous thrombosis. Adding a thrombolytic drug did not reduce mortality or the incidence of pulmonary embolism, whereas it increased the incidence of bleeding. A meta-analysis of 13 trials failed to show that adding a thrombolytic drug to initial anticoagulant therapy reduced mortality or recurrences after pulmonary embolism. In the 5 trials that included patients with massive pulmonary embolism, thrombolytic therapy appeared to reduce mortality by about one-half (6% versus 13%). This difference is noteworthy, even if it did not reach the usual threshold of statistical significance. The results of the 6 trials involving patients with deep venous thrombosis, and those of 2 trials and 8 cohort studies in patients with pulmonary embolism at low risk of complications, suggest that outpatient management is acceptable in some cases. Clinical practice guidelines largely agree on the use of LMWH or fondaparinux as initial therapy for most patients with deep venous thrombosis or pulmonary embolism. Unfractionated heparin is generally recommended for patients with renal failure. Thrombolysis is recommended for massive pulmonary embolism and, in some guidelines, for iliofemoral venous thrombosis. In practice, initial treatment of deep venous thrombosis and pulmonary embolism should be based on LMWH in patients without renal failure. Thrombolytic agents may be useful in case of massive pulmonary embolism, but more evaluation is needed. Bleeding and heparin thrombocytopenia are the main adverse effects of these treatments.

As members of the glycosaminoglycan (GAG) family, heparin and heparan sulfate (HS) are responsible for mediation of a wide range of essential biological actions, most of which are mediated by specific patterns of modifications of regions of these polysaccharides. To fully understand the regulation of HS modification and the biological function of HS through its interactions with protein ligands, it is essential to know the specific HS sequences present. However, the sequencing of mixtures of HS oligosaccharides presents major challenges due to the lability of the sulfate modifications, as well as difficulties in separating isomeric HS chains. Here, we apply a sequential chemical derivatization strategy involving permethylation, desulfation and trideuteroperacetylation to label original sulfation sites with stable and hydrophobic trideuteroacetyl groups. The derivatization chemistry differentiates between all possible heparin/HS sequences solely by glycosidic bond cleavages, without the need to generate cross-ring cleavages. This derivatization strategy combined with LC-MS/MS analysis has been used to separate and sequence five synthetic HS-like oligosaccharides of sizes up to dodecasaccharide, as well as a highly-sulfated Arixtra-like heptamer. This strategy offers a unique capability for the sequencing of microgram quantities of HS oligosaccharide mixtures by LC-MS/MS.

Pharmacological thromboprophylaxis (TP) is known to reduce venous thromboembolism (VTE) in medical inpatients, but the criteria for risk-driven prescription, safety and impact on mortality are still debated. We analyze data on elderly patients with multimorbidities admitted in the year 2010 to the Italian internal medicine wards participating in the REPOSI registry to investigate the rate of TP during the hospital stay, and analyze the factors that are related to its prescription. Multivariate logistic regression, area under the ROC curve and CART analysis were performed to look for independent predictors of TP prescription. Association between TP and VTE, bleeding and death in hospital and during the 3-month post-discharge follow-up were explored by logistic regression and propensity score analysis. Among the 1,380 patients enrolled, 171 (15.2 %) were on TP during the hospital stay (162 on low molecular weight heparins, 9 on fondaparinux). The disability Barthel index was the main independent predictor of TP prescription. Rate of fatal and non-fatal VTE and bleeding during and after hospitalization did not differ between TP and non-TP patients. In-hospital and post-discharge mortality was significantly higher in patients on TP, that however was not an independent predictor of mortality. Among elderly medical patients there was a relatively low rate of TP, that was more frequently prescribed to patients with a higher degree of disability and who had an overall higher mortality.

PURPOSE:

Oral bioavailability of low molecular weight heparin (LMWH) can be achieved by several advanced drug delivery approaches. Here, a new preparation method for coacervates (CAs) using non-toxic polyethylene glycol derivates was developed.

METHODS:

LMWH were coacervated with polyaminomethacrylates (Eudragit® RL or RS) using polyethylene glycol (PEG) derivatives as non-toxic solvents. CAs were analyzed for their physicochemical properties and pharmacokinetic parameters were determined for different formulations in rabbits.

RESULTS:

CAs from both polymer types using various PEGs were of irregular shape and had particle sizes of around 40 μm, encapsulation efficiencies of >90%, and complete LMWH in vitro release was obtained within 2 h. In vivo, oral Absorption at doses of 300 IU/kg was rather low (F < 2.5%) while dose increase resulted in a maximum at 600 IU/kg (FRL: 6.0 ± 1.2%; FRS: 5.8 ± 2.5%) and 1,200 IU/kg did not result in higher bioavailability (FRL: 4.6 ± 0.4%; FRS: 4.1 ± 0.8%). CAs were applicable to various LMWH types where the oral availability decreased in the order fondaparinux>enoxaparin>nadroparin>certoparin depending mainly on the molecular weight.

CONCLUSIONS:

CAs prepared by an organic solvent-free method allowed the oral delivery of LMWHs. The therapeutic efficiency and the simple and solvent-free manufacturing process underlines the high potential of this new preparation method.

Anticoagulants are a mainstay of cardiovascular therapy, and parenteral anticoagulants have widespread use in cardiology, especially in acute situations. Parenteral anticoagulants include unfractionated heparin, low-molecular-weight heparins, the synthetic pentasaccharides fondaparinux, idraparinux and idrabiotaparinux, and parenteral direct thrombin inhibitors. The several shortcomings of unfractionated heparin and of low-molecular-weight heparins have prompted the development of the other newer agents. Here we review the mechanisms of action, pharmacological properties and side effects of parenteral anticoagulants used in the management of coronary heart disease treated with or without percutaneous coronary interventions, cardioversion for atrial fibrillation, and prosthetic heart valves and valve repair. Using an evidence-based approach, we describe the results of completed clinical trials, highlight ongoing research with currently available agents, and recommend therapeutic options for specific heart diseases.

AIMS:

In a model of acute inflammation, Factor Xa inhibitors have been reported not only to suppress the coagulation system but also to exert anti-inflammatory effects. However, this has not been experimentally demonstrated in a model of chronic inflammation. Recent studies demonstrated that vascular inflammation in the metabolic syndrome plays major roles in the development of thrombotic diseases. Therefore, we examined the anti-inflammatory effects of fondaparinux, a Factor Xa inhibitor, in a mouse model of the metabolic syndrome, looking at both leukocyte adhesion on the vascular endothelium and thrombus formation.

METHODS:

Following clamping of the mesenteric vein for 20 minutes in the KK-A(y) mouse, mice were administered by subcutaneous injection either low-dose or high-dose fondaparinux or placebo (n=10 in each group. Microscopic observation of the intestinal microcirculation was carried-out. In another series, blood samples were taken and measured for blood cell counts and organ damage markers (n= 6 in each).

RESULTS:

Both leukocyte adherence and thrombus formation were inhibited by treatment with fondaparinux. RBC and WBC counts were maintained better in high-dose group. Levels of alanine aminotransferase (ALT) were significantly reduced in both low-dose and high-dose groups (p< 0.05 and 0.01, compared to control, respectively).

CONCLUSIONS:

Factor Xa inhibitor attenuates leukocyte adhesion and leukocyte-platelet conjugate formation in a mouse model of the metabolic syndrome. These effects appeared to be related to both inhibition of thrombus formation and reduction in markers of organ damage. © 2012 Blackwell Publishing Ltd.