Review: Low-molecular-weight heparin-induced osteoporosis and osteoporotic fractures: a myth or an existing entity?

Being precise with anticoagulation to reduce adverse drug reactions: are we there yet?

Anticoagulants are potent therapeutics widely used in medical and surgical settings, and the amount spent on anticoagulation is rising. Although warfarin remains a widely prescribed oral anticoagulant, prescriptions of direct oral anticoagulants (DOACs) have increased rapidly. Heparin-based parenteral anticoagulants include both unfractionated and low molecular weight heparins (LMWHs). In clinical practice, anticoagulants are generally well tolerated, although interindividual variability in response is apparent. This variability in anticoagulant response can lead to serious incident thrombosis, haemorrhage and off-target adverse reactions such as heparin-induced thrombocytopaenia (HIT). This review seeks to highlight the genetic, environmental and clinical factors associated with variability in anticoagulant response, and review the current evidence base for tailoring the drug, dose, and/or monitoring decisions to identified patient subgroups to improve anticoagulant safety. Areas that would benefit from further research are also identified. Validated variants in VKORC1, CYP2C9 and CYP4F2 constitute biomarkers for differential warfarin response and genotype-informed warfarin dosing has been shown to reduce adverse clinical events. Polymorphisms in CES1 appear relevant to dabigatran exposure but the genetic studies focusing on clinical outcomes such as bleeding are sparse. The influence of body weight on LMWH response merits further attention, as does the relationship between anti-Xa levels and clinical outcomes. Ultimately, safe and effective anticoagulation requires both a deeper parsing of factors contributing to variable response, and further prospective studies to determine optimal therapeutic strategies in identified higher risk subgroups.

Ultrasound-induced destruction of heparin-loaded microbubbles attenuates L-arginine-induced acute pancreatitis

PURPOSE

Acute pancreatitis (AP) involves sudden inflammation caused by abnormal activation of pancreatic enzymes. The mechanisms underlying AP include oxidative stress, high levels of inflammatory mediators and inflammatory cell infiltration. Heparin, a key therapeutic drug, exerts anti-inflammatory, antioxidative, and anticoagulative effects. However, safe and effective drug delivery remains an obstacle. This study is the first to investigate the therapeutic effects of heparin-loaded microbubbles (HPMB) combined with ultrasound (UHPMB) and the role of heparin in acoustic cavitation.

METHODS

The characteristics of the microbubbles, including particle size, concentration, release, stability, and development, were studied. Heparin concentration in the HPMB was measured, and heparin-induced anticoagulation was evaluated. Drug safety was explored using hemolysis and cell viability assessments. The ability of HPMB to alleviate oxidative stress and inflammation were investigated in vitro. L-arginine induces AP in vivo. UHPMB was used for AP treatment. Serum amylase levels were measured and pancreatic architecture and pathological features were evaluated to determine AP severity. In vivo efficacy was evaluated, and the underlying mechanism of heparin action during acoustic cavitation was explored.

RESULTS

HPMB was spherical and presented as an emulsion-like solution without aggregation. HPMB was visible and stable and effectively released the drug under ultrasound (US). HPMB and UHPMB led to lower AP severity than in the untreated group. US-targeted microbubble destruction (UTMD) enhanced the therapeutic effect by decreasing oxidative stress and inflammation in AP models without injuring vital organs. UHPMB regulated VEGF/Flt-1 and SOD-1 expression. HPMB can also mitigate oxidative stress and inflammation in H₂O₂-pretreated cells.

CONCLUSION

UHPMB exhibits a strong ability not only to selectively target pancreatic lesions and release heparin but also to provide efficient protection by inhibiting oxidative stress and inflammation.

Pharmacological and clinical application of heparin progress: An essential drug for modern medicine

Heparin is the earliest and most widely used anticoagulant and antithrombotic drug that is still used in a variety of clinical indications. Since it was discovered in 1916, after more than a century of repeated exploration, heparin has not been replaced by other drugs, but a great progress has been made in its basic research and clinical application. Besides anticoagulant and antithrombotic effects, heparin also has antitumor, anti-inflammatory, antiviral, and other pharmacological activities. It is widely used clinically in cardiovascular and cerebrovascular diseases, lung diseases, kidney diseases, cancer, etc., as the first anticoagulant medicine in COVID-19 exerts anticoagulant, anti-inflammatory and antiviral effects. At the same time, however, it also leads to a lot of adverse reactions, such as bleeding, thrombocytopenia, elevated transaminase, allergic reactions, and others. This article comprehensively reviews the modern research progress of heparin compounds; discusses the structure, preparation, and adverse reactions of heparin; emphasizes the pharmacological activity and clinical application of heparin; reveals the possible mechanism of the therapeutic effect of heparin in related clinical applications; provides evidence support for the clinical application of heparin; and hints on the significance of exploring the wider application fields of heparin.

How I treat venous thromboembolism in pregnancy

One to 2 pregnant women in 1000 will experience venous thromboembolism (VTE) during pregnancy or postpartum. Pulmonary embolism (PE) is a leading cause of maternal mortality, and deep vein thrombosis leads to maternal morbidity, with postthrombotic syndrome potentially diminishing quality of life for a woman's lifetime. However, the evidence base for pregnancy-related VTE management remains weak. Evidence-based guideline recommendations are often extrapolated from nonpregnant women and thus weak or conditional, resulting in wide variation of practice. In women with suspected PE, the pregnancy-adapted YEARS algorithm is safe and efficient, rendering computed tomographic pulmonary angiography to rule out PE unnecessary in 39%. Low molecular weight heparin (LMWH) in therapeutic doses is the treatment of choice during pregnancy, and anticoagulation (LMWH or vitamin K antagonists [VKAs]) should be continued until 6 weeks after delivery, with a 3-month minimum total duration. LMWH or VKA use does not preclude breastfeeding. Postpartum, direct oral anticoagulants are an option if a woman does not breastfeed and long-term use is intended. Management of delivery, including type of analgesia, requires a multidisciplinary approach and depends on local preferences and patient-specific conditions. Several options are possible, including waiting for spontaneous delivery with temporary LMWH interruption. Prophylaxis for recurrent VTE prevention in subsequent pregnancies is indicated in most women with a history of VTE.

Osteoporotic fracture rates in chronic hemodialysis and effect of heparin exposure: a retrospective cohort study

Background

Patients receiving chronic hemodialysis treatments are at a higher risk of fracture compared to the general population. While the use of heparin during dialysis is crucial to avoid thrombosis of the extracorporeal circuit, the association of unfractionated heparin (UFH) and the risk of osteoporotic fracture has been shown for many years. However, this association was not as clear for low-molecular-weight heparin (LMWH) and the few collected data originated from studies among pregnant women. Our aim was to measure osteoporotic fracture rate among hemodialysis patients and to evaluate the association of LMWH compared to UFH in hemodialysis.

Methods

A retrospective cohort study was conducted on data extracted from the RAMQ and Med-Echo databases from January 2007 to March 2013 with patients chronically hemodialyzed in 21 participating centers. Incidence rates for each fracture sites were measured per 1000 patient-year (p-y) and their 95% confidence intervals (CI). Osteoporotic fracture risk for a first event with LMWH compared to UFH was estimated using a cox proportional hazard model using demographics, comorbidities and drug use as covariates.

Results

4796 patients undergoing chronic hemodialysis were identified. The incidence rate for all fracture sites was 22.7 /1000 p-y (95% CI: 19.6–26.1) and 12.8 /1000 p-y (95% CI: 10.5–15.4) for hip and femur fractures. We found a similar risk of osteoporotic fracture for LMWH compared to UFH (adjusted HR = 1.01; 95%CI: 0.72–1.42). Age and malignancy increased the risk of fracture while cerebrovascular disease decreased the risk of fracture.

Conclusions

Compared to UFH, LMWH did not change the risk of osteoporotic fracture when used for the extracorporeal circuit anticoagulation in chronic hemodialysis.

Treatment of cancer-associated thrombosis: The evolution of anticoagulant choice and clinical insights into practical management

Low-molecular-weight heparin (LMWH) therapy is recommended over vitamin K antagonists (VKAs) for the treatment of cancer-associated thrombosis (CAT) and extended therapy is recommended in those with active cancer to prevent recurrent thrombosis. However, the inconvenience of daily subcutaneous injections and the cost of LMWH therapy hinder long-term use. Observational data demonstrate that persistence with LMWH therapy is low in clinical practice and that many patients are switched to oral alternatives - namely VKAs and direct oral anticoagulants (DOACs). Recently, the efficacy and safety of apixaban, edoxaban, and rivaroxaban versus LMWH therapy for the treatment of CAT have been demonstrated in randomized trials. This review provides a critical evaluation of studies with DOACs in this setting and an update on the guidance regarding anticoagulant use for the treatment of CAT. In recognition of the heterogeneity of patients with cancer and the challenges of CAT, patient cases with expert clinical perspectives are presented.

The Anticoagulant and Nonanticoagulant Properties of Heparin

Heparins represent one of the most frequently used pharmacotherapeutics. Discovered around 1926, routine clinical anticoagulant use of heparin was initiated only after the publication of several seminal papers in the early 1970s by the group of Kakkar. It was shown that heparin prevents venous thromboembolism and mortality from pulmonary embolism in patients after surgery. With the subsequent development of low-molecular-weight heparins and synthetic heparin derivatives, a family of related drugs was created that continues to prove its clinical value in thromboprophylaxis and in prevention of clotting in extracorporeal devices. Fundamental and applied research has revealed a complex pharmacodynamic profile of heparins that goes beyond its anticoagulant use. Recognition of the complex multifaceted beneficial effects of heparin underscores its therapeutic potential in various clinical situations. In this review we focus on the anticoagulant and nonanticoagulant activities of heparin and, where possible, discuss the underlying molecular mechanisms that explain the diversity of heparin's biological actions.

Prevention of Venous Thromboembolism during Pregnancy and the Puerperium with a Special Focus on Women with Hereditary Thrombophilia or Prior VTE-Position Paper of the Working Group in Women's Health of the Society of Thrombosis and Haemostasis (GTH)

Venous thromboembolism (VTE) is a major cause of maternal morbidity during pregnancy and the postpartum period. Because there is a lack of adequate study data, management strategies for the prevention of VTE during pregnancy have mainly been deduced from case-control and observational studies and extrapolated from recommendations for non-pregnant patients. The decision for or against pharmacologic thromboprophylaxis must be made on an individual basis weighing the risk of VTE against the risk of adverse side effects such as severe bleeding complications. A comprehensive, multidisciplinary approach is often essential as the clinical scenario is made more complex by the specific obstetric context, especially in the peripartum period. As members of the Working Group in Women's Health of the Society of Thrombosis and Haemostasis (GTH), we summarize the evidence from the available literature and aim to establish a more uniform strategy for VTE risk assessment and thromboprophylaxis in pregnancy and the puerperium. In this document, we focus on women with hereditary thrombophilia, prior VTE and the use of anticoagulants that can safely be applied during pregnancy and the lactation period.

Contemporary best practice in the management of pulmonary embolism during pregnancy

Approximately 1-2 per 1000 pregnancies are complicated by venous thromboembolism (VTE). VTE includes deep vein thrombosis (DVT) and pulmonary embolism (PE) and the diagnostic management of pregnancy-related VTE is challenging. Current guidelines vary greatly in their approach to diagnosing PE in pregnancy as they base their recommendations on scarce and weak evidence. The pregnancy-adapted YEARS diagnostic algorithm is well tolerated and is the most efficient diagnostic algorithm for pregnant women with suspected PE, with 39% of women not requiring computed tomographic pulmonary angiography. Low-molecular-weight heparin is the first-choice anticoagulant treatment in pregnancy and should be continued until 6 weeks postpartum and for a minimum of 3 months. Direct oral anticoagulants should be avoided in women who want to breastfeed. Management of delivery needs a multidisciplinary approach in order to decide on an optimal delivery plan. Neuraxial analgesia can be given in most patients, provided time windows since last low-molecular-weight heparin dose are respected. Women with a history of VTE are at risk of recurrence during pregnancy and in the postpartum period. Therefore, in most women with a history of VTE, thromboprophylaxis in subsequent pregnancies is indicated. The reviews of this paper are available via the supplemental material section.

Anticoagulants and Osteoporosis

Anticoagulant agents are widely used in the treatment of thromboembolic events and in stroke prevention. Data about their effects on bone tissue are in some cases limited or inconsistent (oral anti-vitamin K agents), and in others are sufficiently strong (heparins) to suggest caution in their use in subjects at risk of osteoporosis. This review analyses the effects of this group of drugs on bone metabolism, on bone mineral density, and on fragility fractures. A literature search strategy was developed by an experienced team of specialists by consulting the MEDLINE platform, including published papers and reviews updated to March 2019. Literature supports a detrimental effect of heparin on bone, with an increase in fracture rate. Low molecular weight heparins (LMWHs) seem to be safer than heparin. Although anti-vitamin K agents (VKAs) have a significant impact on bone metabolism, and in particular, on osteocalcin, data on bone mineral density (BMD) and fractures are contrasting. To date, the new direct oral anticoagulants (DOACs) are found to safe for bone health.

Pregnancy-related osteoporotic vertebral compression fractures in two patients treated with low-molecular-weight heparin during pregnancy: case reports

Pregnancy-related osteoporosis (PRO) is an uncommon metabolic bone disease that can result in vertebral fragility fractures. Here we report two cases of young women who had been previously treated with LMWH-enoxaparin and were diagnosed with PRO with vertebral fragility fractures after delivery. In first case report, a 33-year-old primigravid woman who was treated with 40 mg/day of enoxaparin for eight months to prevent venous thromboembolism was presented. After delivery, Dual energy X ray absorptiometry (DEXA) revealed osteoporosis in lumbar and femoral neck region. In magnetic resonance imaging (MRI), T4-T7 thoracic vertebral height losses were detected. In second case report, a 28-year-old primigravid woman which was treated with 40 mg/day enoxparin from the second month to the birth was presented. Osteoporosis in lumbar region was detected by DEXA. MRI revealed T12-L1 and L5 vertebral height losses. In conclusion, PRO can cause severe low back pain and should be considered in differential diagnosis. A detailed medical history should be essential to detect relationship between LMWH and PRO.

Clinical Case: Pregnancy lactation osteoporosis

Pregnancy-lactation osteoporosis (PLO) is a rare condition with most cases appearing during the third trimester of pregnancy or early in the post-partum period, especially in primigravid women. Our knowledge concerning its pathogenesis is scarce although it seems that most women who experience fragility fractures during this period have a pre-existing bone disease which is further burdened by the mechanical and metabolic changes during pregnancy and lactation. Breastfeeding produces an obligatory loss of maternal skeletal mineral which contributes to the decline of bone density. Little is known whether pharmacological treatments exert a beneficial role upon the situation of PLO since there is lack of firm evidence and bone density seems to recumb spontaneously during weaning.

Effects of Long-Term Low-Molecular-Weight Heparin on Fractures and Bone Density in Non-Pregnant Adults: A Systematic Review With Meta-Analysis

BACKGROUND

Adults who require long-term anticoagulation with low-molecular-weight heparin (LMWH) such as cancer patients or the elderly may be at increased risk of fractures.

OBJECTIVE

To determine the effects of LMWH therapy of at least 3 months' duration on fractures and bone mineral density (BMD) in non-pregnant adult populations.

METHODS

We systematically reviewed electronic databases (e.g., MEDLINE, EMBASE), conferences and bibliographies until June 2015 and included comparative studies in non-pregnant adult populations that examined the effects of LMWH (≥3 months) on fractures and BMD. We synthesized evidence qualitatively and used random-effects meta-analysis to quantify the effect of LMWH on fractures.

RESULTS

Sixteen articles reporting 14 studies were included: 10 clinical trials (n = 4865 participants) and four observational cohort studies (3 prospective, n = 221; 1 retrospective, n = 30). BMD and fractures were secondary outcomes in the majority of trials, while they were primary outcomes in the majority of observational studies. In participants with venous thromboembolism and underlying cardiovascular disease or cancer (5 RCTs, n = 2280), LMWH for 3-6 months did not increase the relative risk of all fractures at 6-12 months compared to unfractionated heparin, oral vitamin K antagonists or placebo [pooled risk ratio (RR) = 0.58, 95 % CI: 0.23-1.43; I(2) = 12.5 %]. No statistically significant increase in the risk of fractures at 6-12 months was found for cancer patients (RR = 1.08, 95 % CI: 0.31-3.75; I(2) = 4.4 %). Based on the data from two prospective cohort studies (n = 166), LMWH for 3-24 months decreased mean BMD by 2.8-4.8 % (depending on the BMD site) compared to mean BMD decreases of 1.2-2.5 % with oral vitamin K antagonists.

CONCLUSIONS

LMWH for 3-6 months may not increase the risk of fractures, but longer exposure for up to 24 months may adversely affect BMD. Clinicians should consider monitoring BMD in adults on long-term LMWH who are at increased risk of bone loss or fracture.

Histopathologic effects of a low molecular weight heparin on bone healing in rats: a promising adjuvant in dacryocystorhinostomy

AIM

To investigate the effect of short-term prophylactic dose of a low molecular weight heparin (LMWH) drug on the bone healing process in an animal model simulating the osteotomy obtained in dacryocystorhinostomy.

METHODS

Forty male Wistar albino rats were divided into 2 groups. Subcutaneous injections of enoxaparin 1 mg/kg (enoxaparin-treated group) and saline solution (control group) were performed once daily for 4d, beginning on the first preoperative day. The osteotomy was created at the femoral diaphysis in all animals by using a Kirschner wire. Each group was further divided into 2 subgroups depending on the timing of the second operation, 14 or 21d following initial osteotomy. Patent osteotomy area on the second and the third weeks in each group were calculated by using a computer software on digital micrographs.

RESULTS

The patent osteotomy areas at the second and the third weeks were significantly larger in the enoxaparin-treated group than those of the control group (P<0.001 for each time-period). In the control group, the patent osteotomy area at the third week of healing was significantly smaller than that of the second week (P=0.003), whereas there was no significant difference between these two measurements in the enoxaparin-treated group (P=0.185).

CONCLUSION

Short-term administration of enoxaparin resultes in a significant alteration in bone healing at 14 and 21d after injury. LMWHs can be regarded as promising alternative adjuvants in dacryocystorhinostomy after being evaluated with further clinical and animal studies.

Guidance for the treatment and prevention of obstetric-associated venous thromboembolism

Venous thromboembolism (VTE), which may manifest as pulmonary embolism (PE) or deep vein thrombosis (DVT), is a serious and potentially fatal condition. Treatment and prevention of obstetric-related VTE is complicated by the need to consider fetal, as well as maternal, wellbeing when making management decisions. Although absolute VTE rates in this population are low, obstetric-associated VTE is an important cause of maternal morbidity and mortality. This manuscript, initiated by the Anticoagulation Forum, provides practical clinical guidance on the prevention and treatment of obstetric-associated VTE based on existing guidelines and consensus expert opinion based on available literature where guidelines are lacking.

Gold nanoparticles modified with self-assembled hybrid monolayer of triblock aptamers as a photoreversible anticoagulant

We demonstrated that thrombin-binding aptamer-conjugated gold nanoparticles (TBA-Au NPs), prepared from a self-assembled hybrid monolayer (SAHM) of triblock aptamers on Au NPs (13 nm), can effectively inhibit thrombin activity toward fibrinogen. The first block poly(adenine) at the end of the triblock TBA was used for the self-assembly on Au NP surface. The second block, in the middle of TBA, was composed of oligonucleotides that could hybridize with each other. The third block, containing TBA15 (15-base, binding to the exosite I of thrombin) and TBA29 (29-base, binding to the exosite II of thrombin) provided bivalent interaction with thrombin. The SAHM triblock aptamers have optimal distances between TBA15 and TBA29, aptamer density, and orientation on the Au NP surfaces. These properties strengthen the interactions with thrombin (Kd=1.5 × 10(-11)M), resulting in an extremely high anticoagulant potency. The thrombin clotting time mediated by SAHM TBA15/TBA29-Au NPs was >10 times longer than that of four commercially available drugs (heparin, argatroban, hirudin, or warfarin). In addition, the rat-tail bleeding assay time further demonstrated that the SAHM TBA15/TBA29-Au NPs were superior to heparin. The SAHM TBA15/TBA29-Au NPs exhibited excellent stability in the human plasma (half-life >14 days) and good biocompatibility (low cytotoxicity and hemolysis). Most interestingly, the inhibition by SAHM TBA15/TBA29-Au NPs was controllable by the irradiation of green laser, via heat transfer-induced TBA release from Au NPs. Therefore, these easily prepared (self-assembled), low cost (non-thiolated aptamer), photo-controllable, multivalent TBA15/TBA29-Au NPs (high density of TBA15/TBA29 on Au NPs) show good potential for the treatment of various diseases related to blood-clotting disorders. Our study opens up the possibility of regulation of molecule binding, protein recognition, and enzyme activity using SAHM aptamer-functionalized nanomaterials.

Treatment with acetylsalicylic acid prevents short to mid-term radiographic progression of nontraumatic osteonecrosis of the femoral head: a pilot study

BACKGROUND

Nontraumatic osteonecrosis of the femoral head (ONFH) is a progressive disease in young adults producing substantial morbidity and frequently resulting in total hip arthroplasty. Although hip-preserving surgical procedures represent the current mainstay of treatment for early disease, medical therapies targeting specific pathways in the ONFH pathogenesis could help prevent disease progression while producing less morbidity. Acetylsalicylic acid (ASA) is a promising alternative to other therapies for ONFH owing to its anti-inflammatory and antithrombotic mechanisms of action and its relatively benign side effect profile.

METHODS

We followed a prospective cohort of 10 patients (12 hips) with precollapse ONFH who were given ASA to prevent disease progression. Their outcomes were compared with those of a historic control group taken from the literature.

RESULTS

Progression occurred in 1 of 12 (8%) patients taking ASA compared with 30 of 45 (66.6%) controls (p = 0.002) at a mean follow-up of 3.7 years. Patients taking ASA also tended to exhibit decreased femoral head involvement at the end of therapy.

CONCLUSION

This hypothesis-generating study leads us to believe that ASA may be a simple and effective treatment option for delaying disease progression in patients with early-stage ONFH.

The Effect of Low Molecular Weight Heparins on Fracture Healing

Venous Thromboembolism is a serious complication in the trauma patient. The most commonly studied and used anticoagulant treatment in prophylaxis of thrombosis is heparin. The prolonged use of unfractionated heparin has been connected with increased incidence of osteoporotic fractures. Low molecular-weight-heparins (LMWHs) have been the golden rule in antithrombotic therapy during the previous two decades as a way to overcome the major drawbacks of unfractioned heparin. However there are few studies reporting the effects of LMWHs on bone repair after fractures. This review presents the studies about the effects of LMWHs on bone biology (bone cells and bone metabolism) and underlying the mechanisms by which LMWHs may impair fracture healing process. The authors' research based on literature concluded that there are no facts and statistics for the role of LMWHs on fracture healing process in humans and the main body of evidence of their role comes from in vitro and animal studies. Further large clinical studies designed to compare different types of LMWHs, in different dosages and in different patient or animal models are needed for exploring the effects of LMWHs on fracture healing process.

[Pharmacogenic osteoporosis beyond cortisone. Proton pump inhibitors, glitazones and diuretics]

BACKGROUND

[corrected] There are many drugs which can cause osteoporosis or at least favor its initiation. The effect of hormones and drugs with antihormonal activity, such as glucocorticoids and aromatase inhibitors, on initiation of osteoporosis is well known. In addition, proton pump inhibitors, glitazones and diuretics also influence the formation of osteoporosis.

MATERIAL AND METHODS

The results of currently available studies on the correlation between proton pump inhibitors, glitazones and diuretics on formation of osteoporosis were evaluated and summarized.

RESULTS

Proton pump inhibitors and glitazones increase the risk for osteoporotic fractures. Loop diuretics may slightly increase fracture risk, whereas thiazides were shown to be osteoprotective by reducing fracture probability on a relevant scale.

CONCLUSION

Proton pump inhibitors should not be prescribed without serious consideration and then only as long as necessary. Alternatively, the administration of the less effective H2 antagonists should be considered when possible due to the reduction of acid secretion. Because the long-term intake of thiazides is associated with a clinically relevant reduction in the risk of fractures and they are economic and well-tolerated, prescription can be thoroughly recommended within the framework of differential diagnostic considerations in an appropriate clinical context. The briefly increased risk of falling immediately after starting diuretic therapy is the only point which needs to be considered.

Elucidating the specificity of non-heparin-based conformational activators of antithrombin for factor Xa inhibition

Introduction:

Antithrombin, the principal inhibitor of coagulation proteases, requires allosteric activation by its physiological cofactor, heparin or heparin sulfate to achieve physiologically permissible rates. This forms the basis of heparin's use as a clinical anticoagulant. However, heparin therapy is beset with severe complications, giving rise to the need to search new non-heparin activators of antithrombin, devoid of these complications and with favorable safety profiles.

Materials and Methods:

We chose some representative organic compounds that have been shown to be involved in coagulation modulation by affecting antithrombin and applied a blind docking protocol to find the binding energy and interactions of the modified (sulfated) versus unmodified organic scaffolds.

Results and Conclusion:

Increased sulfation plays a key role in shifting the specificity of organic compounds like quercetin, diosmin, rutin, mangiferin, isomangostin, Trapezifolixanthone and benzofuran towards the heparin binding site (HBS). However, in hesperetin and tetrahydroisoquinoline, sulfation shifts the specificity away from HBS. We have further tried to elucidate changes in the binding affinity of quercetin on account of gradual increase in the number of hydroxyl groups being substituted by sulfate groups. The results show gradual increase in binding energy with increase in sulfation. A theoretical screening approach is an ideal mechanism to predict lead molecules as activators of antithrombin and in determining the specificity for antithrombin.

[Long-term low-molecular-weight heparin therapy during pregnancy: is there a bone risk?]

Unfractionated heparin (UFH) and low-molecular-weight heparins (LMWH) are broadly used for the thromboprophylaxis during pregnancy. Long-term heparin therapy has raised concern about the risk of bone loss and osteoporotic fractures while pregnancy by itself favors osteoporosis. Experimental studies show a comparable effect of UFH and LMWH on bone formation while UFH has a more marked effect on bone resorption. Available clinical studies do not provide evidence of a difference between UFH and LMWH or among different LMWH on the bone risk. However, clinical studies show that bone loss observed with LMWH is not different from the physiological loss related to pregnancy, and osteoporotic fractures are associated with comorbidities or osteoporosis risk factors. LMWH represent the preferred alternative for thromboprophylaxis during pregnancy.

New directions in the diagnosis and treatment of pulmonary embolism in pregnancy

The diagnosis and management of pulmonary embolism in pregnancy is difficult, because diagnostic procedures and the use of anticoagulants potentially can expose mother and fetus to adverse effects. This article reviews evidence for current best practice and emerging novel techniques for the diagnosis of pulmonary embolism in pregnancy and includes clinical prediction models, biomarkers, and diagnostic imaging that may offer improvement in the diagnosis and investigation of pulmonary embolism in pregnancy in the future. The usefulness of new anticoagulant agents (fondaparinux, rivaroxaban, and dabigatran) in managing pulmonary embolism in future pregnancies is also explored.

[Predilution online hemodiafiltration: which dose of anticoagulation?]

INTRODUCTION

Patients in end stage renal disease on hemodialysis are in higher risk of bleeding related to the anticoagulation used during a session, so only the lowest effective dose of anticoagulation must be used. The aim of this study was to evaluate the efficacy of predilution in hemodiafiltration with reduced dose of anticoagulation compared to hemodialysis in preventing coagulation of circuits.

PATIENTS AND METHODS

This study was conducted in stable hemodialysis patients without high bleeding risk. All patients were treated by two different treatments: (A) conventional hemodialysis, (B) predilution hemodiafiltration with the half dose of anticoagulation used during treatment (A). Other confounding parameters were kept constant during the study. The primary endpoint was the incidence of major thrombotic events judged on a subjective visual score.

RESULTS

Twenty-one patients were included (105 sessions for each treatment). Major incidents are occurring more frequently in predilution hemodiafiltration with reduced dose of anticoagulation (P=0.03). The premature discontinuation of sessions was more frequent in predilution hemodiafiltration, this difference was not significant (P=0.07). Duration of sessions was significantly shorter in predilution hemodiafiltration (P=0.03). The higher frequency of thrombotic events in predilution hemodiafiltration has no effect on net ultrafiltration volume achieved in both treatments.

CONCLUSION

Predilution hemodiafiltration with a lower dose of anticoagulation did not prevent major clotting of extracorporeal circuit manner at least equivalent to a reference method.

[Antiphospholipid syndrome and pregnancy]

Antiphospholipid syndrome is characterized by arterial and venous thromboembolic events and persistent laboratory evidence of antiphospholipid antibodies. Obstetric complications such as recurrent miscarriage, early delivery, oligohydramnios, prematurity, intrauterine growth restriction, fetal distress, fetal or neonatal thrombosis, pre-eclampsia/eclampsia, and HELLP syndrome are also hallmarks of antiphospholipid syndrome. This syndrome is one of the diseases associated with the most severe thrombotic risk. Changes in the hemostatic system during normal pregnancy also result in a hypercoagulable state resulting in elevated thrombotic risk. Thromboembolic events are responsible of the vast majority of maternal and fetal deaths. Administration of appropriate thromboprophylaxis helps prevent thromboembolic complications during pregnancy in women with antiphospholipid syndrome and also give birth to healthy children. It is important to centralize the medication and management of these patients. It helps in the thoughtful care of these pregnant women encountering serious problems.

Pregnancy-associated venous thromboembolism: prevention and treatment

Pregnancy is associated with an increased risk of venous thromboembolism (VTE) and this condition remains an important cause of maternal morbidity and mortality. The use of anticoagulant therapy for treatment and prophylaxis of VTE during pregnancy is challenging because of the potential for fetal, as well as maternal, complications. Although evidence-based recommendations for the use of anticoagulants have been published, given the paucity of available data, guidelines are based largely upon observational studies and from data in nonpregnant patients. This article reviews the available literature and provides guidance for the management and prevention of VTE during pregnancy.

National Cancer Institute, National Heart, Lung and Blood Institute/Pediatric Blood and Marrow Transplantation Consortium First International Consensus Conference on late effects after pediatric hematopoietic cell transplantation: the need for pediatric-specific long-term follow-up guidelines

Existing standards for screening and management of late effects occurring in children who have undergone hematopoietic cell transplantation (HCT) include recommendations from pediatric cancer networks and consensus guidelines from adult-oriented transplantation societies applicable to all HCT recipients. Although these approaches have significant merit, they are not pediatric HCT-focused, and they do not address post-HCT challenges faced by children with complex nonmalignant disorders. In this article we discuss the strengths and weaknesses of current published recommendations and conclude that pediatric-specific guidelines for post-HCT screening and management would be beneficial to the long-term health of these patients and would promote late effects research in this field. Our panel of late effects experts also provides recommendations for follow-up and therapy of selected post-HCT organ and endocrine complications in pediatric patients.

Parenteral anticoagulants: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

This article describes the pharmacology of approved parenteral anticoagulants. These include the indirect anticoagulants, unfractionated heparin (UFH), low-molecular-weight heparins (LMWHs), fondaparinux, and danaparoid, as well as the direct thrombin inhibitors hirudin, bivalirudin, and argatroban. UFH is a heterogeneous mixture of glycosaminoglycans that bind to antithrombin via a unique pentasaccharide sequence and catalyze the inactivation of thrombin, factor Xa, and other clotting enzymes. Heparin also binds to cells and plasma proteins other than antithrombin causing unpredictable pharmacokinetic and pharmacodynamic properties and triggering nonhemorrhagic side effects, such as heparin-induced thrombocytopenia (HIT) and osteoporosis. LMWHs have greater inhibitory activity against factor Xa than thrombin and exhibit less binding to cells and plasma proteins than heparin. Consequently, LMWH preparations have more predictable pharmacokinetic and pharmacodynamic properties, have a longer half-life than heparin, and are associated with a lower risk of nonhemorrhagic side effects. LMWHs can be administered once daily or bid by subcutaneous injection, without coagulation monitoring. Based on their greater convenience, LMWHs have replaced UFH for many clinical indications. Fondaparinux, a synthetic pentasaccharide, catalyzes the inhibition of factor Xa, but not thrombin, in an antithrombin-dependent fashion. Fondaparinux binds only to antithrombin. Therefore, fondaparinux-associated HIT or osteoporosis is unlikely to occur. Fondaparinux exhibits complete bioavailability when administered subcutaneously, has a longer half-life than LMWHs, and is given once daily by subcutaneous injection in fixed doses, without coagulation monitoring. Three additional parenteral direct thrombin inhibitors and danaparoid are approved as alternatives to heparin in patients with HIT.

VTE, thrombophilia, antithrombotic therapy, and pregnancy: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines

BACKGROUND

The use of anticoagulant therapy during pregnancy is challenging because of the potential for both fetal and maternal complications. This guideline focuses on the management of VTE and thrombophilia as well as the use of antithrombotic agents during pregnancy.

METHODS

The methods of this guideline follow the Methodology for the Development of Antithrombotic Therapy and Prevention of Thrombosis Guidelines: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines in this supplement.

RESULTS

We recommend low-molecular-weight heparin for the prevention and treatment of VTE in pregnant women instead of unfractionated heparin (Grade 1B). For pregnant women with acute VTE, we suggest that anticoagulants be continued for at least 6 weeks postpartum (for a minimum duration of therapy of 3 months) compared with shorter durations of treatment (Grade 2C). For women who fulfill the laboratory criteria for antiphospholipid antibody (APLA) syndrome and meet the clinical APLA criteria based on a history of three or more pregnancy losses, we recommend antepartum administration of prophylactic or intermediate-dose unfractionated heparin or prophylactic low-molecular-weight heparin combined with low-dose aspirin (75-100 mg/d) over no treatment (Grade 1B). For women with inherited thrombophilia and a history of pregnancy complications, we suggest not to use antithrombotic prophylaxis (Grade 2C). For women with two or more miscarriages but without APLA or thrombophilia, we recommend against antithrombotic prophylaxis (Grade 1B).

CONCLUSIONS

Most recommendations in this guideline are based on observational studies and extrapolation from other populations. There is an urgent need for appropriately designed studies in this population.

Adverse effects of heparin

All the adverse effects of heparins are related to their wide variety of biological activities, with bleeding being the most important safety issue, resulting directly from the potency of heparin as an anticoagulant. However, it is hard to define the bleeding risk, since it depends on numerous parameters including the indication, dosage, method, and duration of heparin application, the clinical study design and definition of bleeding as well as patient characteristics and determinants of bleeding such as type of surgery and co-medication. Nonbleeding complications of heparins are caused by binding of heparin molecules to proteins other than antithrombin and to cells, which is generally more pronounced with unfractionated heparin than with low-molecular-weight heparins. Accordingly, heparin-induced thrombocytopenia, the most severe nonbleeding adverse reaction, occurs about 10 times less with low-molecular-weight heparins than with unfractionated heparin. Frequent and therefore important adverse reactions of heparins are skin lesions resulting from delayed-type hypersensitivity reactions. All the other undesirable effects are discussed as well, but they are mostly clinically irrelevant.

Osteoporosis piece of multi-morbidity puzzle in geriatric care

Osteoporosis frequently coexists with other chronic diseases and syndromes of aging, and therefore multimorbidity interactions can potentially complicate its evaluation and treatment. This article reviews osteoporosis comorbidity interactions with select common diseases of aging including cardiovascular, neurologic, and geriatric syndromes, and select commonly used medications by older adults. Using depression as a case example, we describe the complex relationship between osteoporosis, mood, and antidepressant medications, and the implications of these interactions for patients and clinicians.

Antiphospohlipid syndrome in obstetrics

Antiphospholipid syndrome is characterised by a variety of clinical and immunological manifestations. The clinical hallmarks of this syndrome are thrombosis and poor obstetric outcomes, including miscarriages, fetal loss and severe pre-eclampsia. The main antiphospholipid antibodies include lupus anticoagulant, anticardiolipin and anti-β2-glycoprotein I. The combination of aspirin and heparin is considered the standard of care for women with antiphospholipid syndrome and embryo-fetal losses; however, aspirin in monotherapy may have a place in women with recurrent early miscarriage. A good benefit-risk ratio of low-molecular-weight heparin in pregnancy thrombosis treatment has been reported. Warfarin must be avoided if possible throughout the first trimester of pregnancy. Adequate pregnancy management of women with antiphospholipid syndrome should include co-ordinated medical-obstetrical care, a close follow-up protocol and a good neonatal unit. Close blood pressure control and early detection of proteinuria, together with Doppler studies of the utero-placental circulation should be included in the management protocol.

Tinzaparin use in pregnancy: an international, retrospective study of the safety and efficacy profile

OBJECTIVES

This study audited pregnancies where the mother received tinzaparin (at any stage before delivery), with a primary objective of determining the maternal safety of this low molecular weight heparin when administered as treatment and/or prophylaxis; the secondary objective was to audit fetal and neonatal safety in this cohort. Efficacy outcomes were also recorded.

STUDY DESIGN

The audit period was 1996-2009; consecutive, retrospective pregnancy records at participating hospitals were reviewed. For those records documenting tinzaparin use and pregnancy outcome, information was extracted into a standardised case report form; these were reviewed for adverse events, which were submitted for adjudication by independent experts in obstetric medicine and haematology. Endpoints were presented using descriptive statistics for all pregnancies, and by reason for tinzaparin use (treatment of venous thromboembolism [VTE] and prophylaxis).

RESULTS

There were 28 participating hospital centres in eight countries (Belgium, Canada, Denmark, Ireland, Netherlands, Sweden, Spain and the UK). Data were collected from 1267 pregnancies (1120 women; 1303 fetuses); in 254 pregnancies the women received tinzaparin as treatment (median dose 13,000 international units [IU]/day, range 3500-23,100IU/day; median duration 72 days; 94.1% once-daily), and in 1013 pregnancies the women received tinzaparin for prophylaxis (median dose 4500IU/day, range 2500-21,811IU/day, median duration 183 days, 94.6% once-daily). There were 871 (70.2%) vaginal deliveries (78 assisted) and 369 (29.8%) caesarean sections (27 delivery data missing). Overall, 495 (39.3%) women had neuraxial anaesthesia; however, there were no reported associated haematomas. There were no maternal deaths. Of pregnancies with available data (1060), 86.9% had blood loss ≤500mL, 11.0% of >500 to ≤1000mL, 0.9% >1000 to ≤1500mL and 1.1% >1500mL. There were 1245 (95.5%) live births, 15 (1.2%) stillbirths, 40 (3.1%) miscarriages and 3 (0.2%) terminations. Six (0.5%) neonatal deaths occurred (five at <27 weeks, one Ebstein's anomaly). No neonatal haemorrhages occurred. Adjudicated safety outcomes included 125 (9.9%) 'any bleeding' cases considered related to tinzaparin; 16 (1.3%) of these required medical intervention. In the treatment group, five (2%) recurrent VTEs were reported and 10 (1%) occurred in the prophylaxis group.

CONCLUSIONS

These data provide reassuring maternal and fetal outcome information in pregnancies exposed to tinzaparin.

Is heparin a placental anticoagulant in high-risk pregnancies?

Randomized control trials show beneficial effects of heparin in high-risk pregnancies to prevent preeclampsia and intrauterine growth restriction. However, the lack of placental pathology data in these trials challenges the assumption that heparin is a placental anticoagulant. Recent data show that placental infarction is probably associated with abnormalities in development of the placenta, characterized by poor maternal perfusion and an abnormal villous trophoblast compartment in contact with maternal blood, than with maternal thrombophilia. At-risk pregnancies may therefore be predicted by noninvasive prenatal testing of placental function in mid-pregnancy. Heparin has diverse cellular functions that include direct actions on the trophoblast. Dissecting the non-anticoagulant actions of heparin may indicate novel and safer therapeutic targets to prevent the major placental complications of pregnancy.

Influence of long-term thromboprophylaxis with low-molecular-weight heparin (enoxaparin) on changes of bone metabolism markers in pregnant women

This is a first descriptive, retrospective, observational study aiming to evaluate the changes in bone turnover markers in pregnant women and to assess the effect of a long-term treatment with low-molecular-weight heparin (LMWH), specifically, enoxaparin. Study involved 50 pregnant Caucasian women with thrombophilia. The patients either received prophylactic enoxaparin once daily subcutaneously (N = 35) or were observed without treatment (N = 15). Concentrations of total serum alkaline phosphatase (total AP), bone alkaline phosphatase (bone AP), osteoprotegerin (OPG), and the receptor activator of nuclear factor κB ligand (RANKL) were measured at 15, 25, and 35 weeks of gestation. Total serum AP increased with gestational age. In the group treated with enoxaparin, the percentage of bone AP concentration was lower (P < .05) than in the control group. Serum OPG also increased with gestational age, but no significant difference was found between the groups with- and without treatment. Despite the OPG increased, RANKL did not change.

Approach to the patient with secondary osteoporosis

Secondary osteoporosis is characterized by low bone mass with microarchitectural alterations in bone leading to fragility fractures in the presence of an underlying disease or medication. Scenarios that are highly suspicious for secondary osteoporosis include fragility fractures in younger men or premenopausal women, very low bone mineral density (BMD) values, and fractures despite anti-osteoporotic therapy. An open-minded approach with a detailed history and physical examination combined with first-line laboratory tests are aimed at identifying clinical risk factors for fractures, osteoporosis-inducing drugs, and underlying endocrine, gastrointestinal, hematologic, or rheumatic diseases, which then need to be confirmed by specific and/or more invasive tests. BMD should be assessed with bone densitometry at the hip and spine. Lateral X-rays of the thoracic and lumbar spine should be performed to identify or exclude prevalent vertebral fractures which may be clinically silent. Management of secondary osteoporosis includes treatment of the underlying disease, modification of medications known to affect the skeleton, and specific anti-osteoporotic therapy. Calcium and vitamin D supplementation should be initiated with doses that result in normocalcemia and serum 25-hydroxyvitamin D concentrations of at least 30 ng/ml. Oral and i.v. bisphosphonates are effective and safe drugs for most forms of secondary osteoporosis. Severe osteoporosis may require the use of teriparatide.