Combined antiplatelet and anticoagulant therapy: clinical benefits and risks

Major Bleeding Events in Hospitalized COVID-19 Patients: A Retrospective Observational Study

Thromboprophylaxis/anticoagulation treatment is often required in hospitalized COVID-19 patients. We aimed to estimate the prevalence of major bleeding events in hospitalized COVID-19 patients. This was a retrospective observational study including all COVID-19 hospitalized patients ≥18 years of age at one reference center in northern Italy. The crude prevalence (between February 2020-2022) of major bleeding events was estimated as the number of major bleeding episodes divided by patients at risk. Uni- and multivariable Cox models were built to assess factors potentially associated with major bleeding events. Twenty-nine (0.98%) out of 2,945 COVID-19 patients experienced a major bleeding event [prevalence of 0.55% (95%CI 0.37-0.79)], of which five were fatal. Patients who experienced a major bleeding event were older [78 years (72-84 IQR) vs. 67 years (55-78 IQR), p-value < 0.001] and more frequently exposed to anti-aggregating therapy (44.8% vs. 20.0%, p-value 0.002) when compared to those who did not. In the multivariable Cox model, age [per 1 year more AHR 1.05 (CI95% 1.02-1.09)] was independently associated with an increased risk of major bleeding events. A strict monitoring of older hospitalized COVID-19 patients is warranted due to the risk of major bleeding events.

Prevalence and differences in the co-administration of drugs known to interact: an analysis of three distinct and large populations

BACKGROUND

The co-administration of drugs known to interact greatly impacts morbidity, mortality, and health economics. This study aims to examine the drug-drug interaction (DDI) phenomenon with a large-scale longitudinal analysis of age and gender differences found in drug administration data from three distinct healthcare systems.

METHODS

This study analyzes drug administrations from population-wide electronic health records in Blumenau (Brazil; 133 K individuals), Catalonia (Spain; 5.5 M individuals), and Indianapolis (USA; 264 K individuals). The stratified prevalences of DDI for multiple severity levels per patient gender and age at the time of administration are computed, and null models are used to estimate the expected impact of polypharmacy on DDI prevalence. Finally, to study actionable strategies to reduce DDI prevalence, alternative polypharmacy regimens using drugs with fewer known interactions are simulated.

RESULTS

A large prevalence of co-administration of drugs known to interact is found in all populations, affecting 12.51%, 12.12%, and 10.06% of individuals in Blumenau, Indianapolis, and Catalonia, respectively. Despite very different healthcare systems and drug availability, the increasing prevalence of DDI as patients age is very similar across all three populations and is not explained solely by higher co-administration rates in the elderly. In general, the prevalence of DDI is significantly higher in women - with the exception of men over 50 years old in Indianapolis. Finally, we show that using proton pump inhibitor alternatives to omeprazole (the drug involved in more co-administrations in Catalonia and Blumenau), the proportion of patients that are administered known DDI can be reduced by up to 21% in both Blumenau and Catalonia and 2% in Indianapolis.

CONCLUSIONS

DDI administration has a high incidence in society, regardless of geographic, population, and healthcare management differences. Although DDI prevalence increases with age, our analysis points to a complex phenomenon that is much more prevalent than expected, suggesting comorbidities as key drivers of the increase. Furthermore, the gender differences observed in most age groups across populations are concerning in regard to gender equity in healthcare. Finally, our study exemplifies how electronic health records' analysis can lead to actionable interventions that significantly reduce the administration of known DDI and its associated human and economic costs.

An eco-friendly ultra-performance liquid chromatography-mass spectrometry method for quantification of rivaroxaban and ticagrelor in rat plasma: grapefruit interactions

Aim: An eco-friendly ultra-performance liquid chromatography-tandem mass spectrometry method was developed to study the pharmacokinetics of rivaroxaban and ticagrelor in rat plasma, utilizing moxifloxacin as an internal standard. The food-drug interaction between grapefruit juice and these drugs was also investigated. Methods: Liquid-liquid extraction was used. A nonporous stationary phase Agilent® Poroshell 120EC C18 column was used with methanol: 0.1% aqueous formic acid (95:5 v/v) as a mobile phase. The detection was performed in multiple reaction monitoring mode using positive electrospray ionization. The method's validation was conducted in accordance with US FDA and European Medicines Agency guidelines. Results & conclusion: Grapefruit juice should be ingested with caution in patients treated with antithrombotic medications as it may increase their plasma concentration, inducing bleeding, and requires close clinical monitoring.

Treatment of cerebral aneurysms with flow diversion or stent assisted coiling in patients on concurrent oral anticoagulation

BACKGROUND

Flow diversion and stent assisted coiling are increasingly utilized strategies in the endovascular treatment of cerebral aneurysms. Ischemic and hemorrhagic complications play an important role in the outcome following such embolizations. Little is published regarding patients on concurrent oral anticoagulation and undergoing such embolizations and the rates of complications and patient outcomes.

MATERIALS AND METHODS

Retrospective data for consecutive patients on concurrent oral anticoagulation undergoing flow diversion or stent assisted coiling for cerebral aneurysms was accessed from databases at the participating sites. Patient demographics, comorbidities, antiplatelet regimens, aneurysm characteristics, complications, and radiographic results were recorded and descriptive statistics reported.

RESULTS

Eleven patients were identified undergoing embolization in the setting of preoperative anticoagulant use and included seven patients undergoing flow diversion and four patients undergoing stent assisted coiling. There was a wide range of antiplatelet and anticoagulant management strategies. There were four major complications in three patients (27.2%) to include two serious bleeding events in addition to ischemic strokes. Both serious bleeding events occurred in patients continued on oral anticoagulation with the addition of antiplatelets. At a mean follow-up of 9.6 months, three aneurysms had continued filling for a good radiographic outcome of 72.7%.

CONCLUSIONS

Anticoagulant and antiplatelet use in the setting of flow diversion or stent assisted coiling may carry increased risks as compared to historical norms and, for flow diversion, offer decreased efficacy.

Antiplatelet therapy for patients with COVID-19: Systematic review and meta-analysis of observational studies and randomized controlled trials

Background

Hyperinflammation and coagulopathy are hallmarks of COVID-19 and synergistically contribute to illness progression. Antiplatelet agents have been proposed as candidate drugs for COVID-19 treatment on the basis of their antithrombotic and anti-inflammatory properties. A systematic review and meta-analysis that included early observational studies and recent randomized controlled trials (RCTs) was performed to summarize and compare evidence on this issue.

Methods

PubMed, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched to identify studies published up to Nov 7, 2021, and the results of registered clinical trials were followed up to Mar 30, 2022. We included RCTs and observational studies assessing the effect of antiplatelet therapy in adult patients with COVID-19. Data on baseline patient characteristics, interventions, controls, and outcomes were extracted by two independent reviewers. The primary outcome was mortality. Data were pooled using a random-effects model.

Results

Twenty-seven studies were included, of which 23 observational studies were pooled in a meta-analysis, and the remaining four RCTs (ACTIV-4B, RECOVERY, ACTIV-4a, and REMAP-CAP) were narratively synthesized. Based on 23 observational studies of 87,824 COVID-19 patients, antiplatelet treatment favors a lower risk of mortality [odds ratio (OR) 0.72, 95% confidence interval (CI) 0.61–0.85; I² = 87.0%, P < 0.01]. The narrative synthesis of RCTs showed conflicting evidence, which did not support adding antiplatelet therapy to the standard care, regardless of the baseline illness severity and concomitant anticoagulation intensity.

Conclusion

While the rationale for using antiplatelet treatment in COVID-19 patients is compelling and was supported by the combined result of early observational studies, evidence from RCTs did not confirm this approach. Several factors that could explain this inconsistency were highlighted alongside perspectives on future research directions.

Direct Oral Anticoagulants and Non-valvular Atrial Fibrillation: Compliance with Dose Level Guidelines in Patients Aged 80 Years and Over

BACKGROUND

Direct oral anticoagulants (DOACs) are currently recommended as first-line or (after vitamin K antagonists) second-line therapy for preventing stroke and systemic embolism in patients with non-valvular atrial fibrillation. In patients aged 80 years and over, however, the fear of DOAC-associated bleeding and the complexity of DOAC dosing regimes may prompt physicians to prescribe inappropriate dose levels.

OBJECTIVE

The objective of this study was to determine compliance with French and European guidelines of doses of three DOACs (apixaban, dabigatran and rivaroxaban) prescribed to patients aged over 80 years in an indication of non-valvular atrial fibrillation, and to identify factors associated with poor compliance.

METHODS

We performed a retrospective single-centre study of patients aged over 80 years routinely treated with a DOAC (apixaban, dabigatran or rivaroxaban) for non-valvular atrial fibrillation at Valenciennes General Hospital (Valenciennes, France) between 1 January, 2016 and 31 December, 2017. We determined compliance with French and European guidelines of DOAC doses as a function of each patient's clinical and laboratory parameters, and thus classified the regime as being appropriately dosed, overdosed or underdosed.

RESULTS

A total of 703 patients (371 taking apixaban, 92 taking dabigatran and 240 taking rivaroxaban) were included in the study. We found that 274 patients (39%) had been prescribed an inappropriate DOAC regime, with underdosing in 241 cases (34%) and overdosing in 33 cases (5%). Underdosing mainly concerned the two most widely prescribed DOACs, i.e. apixaban (39% of all apixaban prescriptions were underdosed) and rivaroxaban (40%). Concomitant treatment with an antidepressant was associated with underdosing of rivaroxaban or apixaban (p = 0.0339). In contrast, initial management in a neurology department was associated with appropriate dosing (p = 0.000146) for both these DOACs.

CONCLUSIONS

Among patients with non-valvular atrial fibrillation aged 80 years and over, about 40% of DOAC prescriptions feature inappropriate dose levels. It might be possible to reduce inappropriate dosing by raising awareness among hospital-based and private-practice prescribers, providing prescription support tools for DOACs, and performing medication reconciliations and reviews at hospital and in private practice.

Dental implants and risk of bleeding in patients on oral anticoagulants: a systematic review and meta-analysis

Background

Dental implant placement is safe and predictable, yet optimal management of anticoagulated patients remains controversial. Whilst cessation of anticoagulation pre-operatively should decrease risks of bleeding, risk of thrombosis increases. We aim to define risk of bleeding in patients on oral anticoagulation who are undergoing dental implant placement, in order to establish best management.

Methods

This systematic review is registered with the National Institute for Health Research (NIHR) PROSPERO database (Registration No: CRD42021233929). We performed a systematic review as per Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidance. Studies were identified using an agreed search strategy within the OVID Gateway (this included Pubmed, MEDLINE, Cochrane Collaborative). Studies assessing bleeding complications in patients who were undergoing dental implant placement were selected. The primary outcome was bleeding events in anticoagulated patients undergoing dental implant placement. Secondary outcomes included any complication requiring further intervention.

Results

We identified 182 studies through screening, and after review of titles and abstracts reduced this to 8 studies. In these studies, 1467 participants received at least 2366 implants. Studies were analysed for quality using the ROBINS-I risk of bias tool. Four studies were retrospective case reviews, and four were prospective reviews, three of which also blinded the operator to anticoagulation status. There was significant heterogeneity between the included studies. Meta-analysis showed an increased risk of bleeding (RR, 2.30; 95% CI, 1.25-4.24 p = 0.37 I = 7%) when implants were placed in the presence of anticoagulation however these were not clinically significant haemorrhagic events.

Conclusion

The continuation of anticoagulants peri-operatively during dental implant surgery does increase the risk of clinically non-significant peri- and post-operative bleeding. Dental implant surgery encompasses a broad spectrum of procedures ranging from minor to more invasive surgery with simple local haemostatic measures mitigating the risk of bleeding. The decision to discontinue anticoagulants prior to dental implant surgery must consider patient and surgical factors with the clinician undertaking a risk-balance assessment.

Discovery of Benzyl Tetraphosphonate Derivative as Inhibitor of Human Factor Xia

The inhibition of factor XIa (FXIa) is a trending paradigm for the development of new generations of anticoagulants without a substantial risk of bleeding. In this report, we present the discovery of a benzyl tetra-phosphonate derivative as a potent and selective inhibitor of human FXIa. Biochemical screening of four phosphonate/phosphate derivatives has led to the identification of the molecule that inhibited human FXIa with an IC50 value of ∼7.4 μM and a submaximal efficacy of ∼68 %. The inhibitor was at least 14-fold more selective to FXIa over thrombin, factor IXa, factor Xa, and factor XIIIa. It also inhibited FXIa-mediated activation of factor IX and prolonged the activated partial thromboplastin time of human plasma. In Michaelis-Menten kinetics experiment, inhibitor 1 reduced the VMAX of FXIa hydrolysis of a chromogenic substrate without significantly affecting its KM suggesting an allosteric mechanism of inhibition. The inhibitor also disrupted the formation of FXIa - antithrombin complex and inhibited thrombin-mediated and factor XIIa-mediated formation of FXIa from its zymogen factor XI. Inhibitor 1 has been proposed to bind to or near the heparin/polyphosphate-binding site in the catalytic domain of FXIa. Overall, inhibitor 1 is the first benzyl tetraphosphonate small molecule that allosterically inhibits human FXIa, blocks its physiological function, and prevents its zymogen activation by other clotting factors under in vitro conditions. Thus, we put forward benzyl tetra-phosphonate 1 as a novel lead inhibitor of human FXIa to guide future efforts in the development of allosteric anticoagulants.

Secondary Stroke Prevention: A Population-Based Cohort Study on Anticoagulation and Antiplatelet Treatments, and the Risk of Death or Recurrence

Using claims databases of a public healthcare program (Quebec) for the years 2010-2013, we conducted a cohort study of patients with acute ischemic stroke (AIS) to describe secondary prevention treatments and determine how they stood against practice guidelines. We compared the risk of death or AIS recurrence over 1 year in patients treated with anticoagulants, antiplatelets, and/or other cardiovascular drugs. In the month after discharge, 44.3% of the patients did not receive the recommended treatment and > 20% did not have any treatment. Untreated patients were younger, had less comorbidities, and a more severe AIS. Anticoagulants and antiplatelets were associated with a reduced risk of death or recurrence (hazard ratio (HR) 0.27; 95% confidence interval (CI) 0.20-0.36 and HR 0.25; 95% CI 0.16-0.38, respectively) compared with the untreated group. Effect size was similar for the other treatments. Findings confirm treatment benefits shown in clinical trials and emphasize the importance of AIS secondary prevention.

Incidence and prognostic implications of late bleeding events after percutaneous mitral valve repair

Objectives

MitraClip is an established therapy for patients with mitral regurgitation (MR) that are considered of high-risk or inoperable. However, late bleeding events (BE) after hospital discharge and their impact on prognosis in this cohort of patients have been poorly investigated. Our purpose is to address the incidence, related factors and clinical implications of BE after hospital discharge in patients treated with MitraClip.

Methods

Prospective registry of all consecutive patients (n = 80) who underwent MitraClip implantation in our Institution between June 2014 and December 2017. BE were defined according to MVARC definitions. A combined clinical end-point including admission for heart failure (HF) and all-cause mortality was established to analyze prognostic implications of BE.

Results

During a median follow up of 523.5 days, 41 BE were reported in 21 patients. Atrial fibrillation (AF, HR 4.54, CI95% 1.20–17.10) and combined antithrombotic therapy at discharge (HR 3.52, CI95% 1.03–11.34) were independently associated with BE. In the study period, 15 (18.8%) patients died, 20 (25%) were admitted for HF and 29 (36.3%) presented the combined end-point. After multivariable adjustment BE remained independently associated with an adverse outcome (HR 3.80, CI 95% 1.66–8.72). In the subgroup of patients with AF, HAS-BLED score was higher among subjects with BE (3.1 ± 1.3 vs 2.1 ± 0.9, p = 0.003). HAS-BLED score had a significant discrimination power for the occurrence BE (AUC: 0.677 [0.507–0.848]) in this subgroup.

Conclusions

BE are common after MitraClip and are associated with an impaired outcome. Strategies to reduce bleeding events are paramount in this cohort of patients.

McMaster RARE-Bestpractices clinical practice guideline on diagnosis and management of the catastrophic antiphospholipid syndrome

Background The McMaster RARE-Bestpractices project group selected the catastrophic antiphospholipid syndrome (CAPS) for a pilot exercise in guideline development for a rare disease. Objectives The objectives of this exercise were to provide a proof of principle that guidelines can be developed for rare diseases and assist in clinical decision making for CAPS. Patients/Methods The GIN-McMaster Guideline Development checklist and GRADE methodology were followed throughout the guideline process. The CAPS guideline was coordinated by a steering committee, and the guideline panel was formed with representation from all relevant stakeholder groups. Systematic reviews were performed for the key questions. To supplement the published evidence, we piloted novel methods, including use of an expert-based evidence elicitation process and ad hoc analysis of registry data. Results This paper describes the CAPS guideline recommendations, including evidence appraisal and discussion of special circumstances and implementation barriers identified by the panel. Many of these recommendations are conditional, because of subgroup considerations in this heterogeneous disease, as well as variability in patient values and preferences. Conclusions The CAPS clinical practice guideline initiative met the objective of the successful development of a clinical practice guideline in a rare disease using GRADE methodology. We expect that clinicians caring for patients with suspected CAPS will find the guideline useful in assisting with diagnosis and management of this rare disease.

Do anticoagulation medications increase the risk of haematoma in ultrasound-guided fine needle aspiration of thyroid lesions?

BACKGROUND

A feared complication of thyroid fine needle aspiration (FNA) is bleeding diathesis and haematoma at the biopsy site. Patients are often advised to discontinue antithrombotic/anticoagulant (AT/AC) medications prior to the procedure. The aim of this study was to examine the risk of bleeding in patients on AT/AC medications undergoing cervical ultrasound (US)-guided FNA.

METHODS

A retrospective chart review of 803 patients who underwent US-guided FNA of thyroid nodules over 8 years by a single endocrine surgeon was undertaken. Clinical variables, patient demographics and use of AT/AC medications were collected and analysed. The principle outcome measures included the incidence of procedure-related haematoma formation. Multivariable logistic regression was used to investigate the possible independent association between post-FNA haematoma and anticoagulation, adjusting for age, African American race, body mass index, vascularity and lesion size.

RESULTS

A total of 1568 lesions were included in 803 patients. The mean age for the patients on AT/AC was 63.0 ± 10.4 years and those not on AT/AC was 50.1 ± 14.2 years (P < 0.001). Of those, 148 patients had 336 lesions (21%) biopsied while taking one or more daily AT/AC agent (81 patients: aspirin; 11 patients: Plavix; 17 patients: aspirin and warfarin; 30 patients: aspirin and Plavix; seven patients: rivaroxaban and aspirin; and two patients: ticagrelor and aspirin). Three patients (0.89%) in the AT/AC group compared to six patients (0.49%) not receiving AT/AC medications developed a haematoma (P = 0.41). All complications were treated conservatively and none required intervention.

CONCLUSIONS

US-guided FNA of thyroid lesions can be safely performed on patients taking AT/AC including newer agents, without an increase in adverse outcomes or decreased diagnostic rate. Further larger prospective multi-institutional studies are warranted to further investigate this important finding.

Antithrombotic Therapy in Patients With Atrial Fibrillation Undergoing Percutaneous Coronary Intervention: A North American Perspective-2016 Update

The optimal antithrombotic treatment regimen for patients with atrial fibrillation undergoing percutaneous coronary intervention with stent implantation is an emerging clinical problem. Currently, there is limited evidenced-based data on the optimal antithrombotic treatment regimen, including antiplatelet and anticoagulant therapies, for these high-risk patients with practice guidelines, thus, providing limited recommendations. Over the past years, expert consensus documents have provided guidance to clinicians on how to manage patients with atrial fibrillation undergoing percutaneous coronary intervention. Given the recent advancements in the field, the current document provides an updated opinion of selected North American experts from the United States and Canada on the treatment of patients with atrial fibrillation undergoing percutaneous coronary intervention. In particular, this document provides the current views on (1) embolic/stroke risk, (2) ischemic/thrombotic cardiac risk, and (3) bleeding risk, which are pivotal for discerning the choice of antithrombotic therapy. In addition, we describe the recent advances in pharmacology, stent designs, and clinical trials relevant to the field. Ultimately, we provide expert consensus-derived recommendations, using a pragmatic approach, on the management of patients with atrial fibrillation undergoing percutaneous coronary intervention.

Synthesis and in Vitro and in Vivo Anticoagulant and Antiplatelet Activities of Amidino- and Non-Amidinobenzamides

Three amidino- and ten non-amidinobenzamides were synthesized as 3-aminobenzoic acid scaffold-based anticoagulant and antiplatelet compounds. The anticoagulant activities of thirteen synthesized compounds 1-13, and 2b and 3b as prodrugs were preliminary evaluated by screening the prolongation of activated partial thromboplastin time (aPTT) and prothrombin time (PT) in vitro. From the aPTT results obtained, two amidinobenzamides, N-(3'-amidinophenyl)-3-(thiophen-2''-ylcarbonylamino) benzamide (1, 33.2 ± 0.7 s) and N-(4'-amidinophenyl)-3-(thiophen-2''-ylcarbonylamino) benzamide (2, 43.5 ± 0.6 s) were selected to investigate the further anticoagulant and antiplatelet activities. The aPTT results of 1 (33.2 ± 0.7 s) and 2 (43.5 ± 0.6 s) were compared with heparin (62.5 ± 0.8 s) in vitro at 30 μM. We investigated the effect of 1 and 2 on blood anticoagulant activity (ex vivo) and on tail bleeding time (in vivo) on mice. A tail cutting/bleeding time assay revealed that both 1 and 2 prolonged bleeding time in mice at a dose of 24.1 g/mouse and above. Compounds 1 and 2 dose-dependently inhibited thrombin-catalyzed fibrin polymerization and platelet aggregation. In addition, 1 and 2 were evaluated on the inhibitory activities of thrombin and FXa as well as the generation of thrombin and FXa in human umbilical vein endothelial cells (HUVECs). Collectively, 1 and 2 possess some antiplatelet and anticoagulant activities and offer a basis for development of a novel antithrombotic product.

Diagnosis and management of pulmonary embolism in the elderly

Elderly patients are a population not only at particularly high risk of venous thromboembolism including pulmonary embolism (PE), but also at high risk of adverse clinical outcomes and treatment-related complications. Major progresses have been achieved in the diagnosis and treatment of PE over the last two decades. Nevertheless, some of elderly patients' specificities still represent important challenges in the management of PE in this population, from its suspicion to its diagnosis and treatment, and are discussed in this review. Perspectives for the future are from a diagnostic point of view the potential implementation of age-adjusted d-dimer cut-offs that will allow ruling out PE in a greater proportion of elderly patients without the need for thoracic imaging. From a therapeutic point of view, acquisition of post-marketing clinical experience with the use of new oral anticoagulants is still necessary, and in the meantime, these drugs should be prescribed with great caution in thoroughly selected elderly patients.

Apixaban: a novel oral inhibitor of factor Xa

PURPOSE

The pharmacology, pharmacokinetics, efficacy, and safety of apixaban are reviewed.

SUMMARY

Apixaban is an oral, direct, selective factor Xa inhibitor with a rapid onset of action. It has a plasma elimination half-life of 12 hours and has been administered in a twice-daily dosing regimen in clinical trials without the need for anticoagulation monitoring or dosage adjustment. Apixaban has multiple elimination pathways, and its pharmacokinetics is not substantially altered by patient age, sex, race, or ethnicity. The results of three Phase III trials indicated that apixaban was similar to or more effective than enoxaparin for preventing venous thromboembolism (VTE) in patients undergoing total hip or knee replacement, with similar or lower rates of bleeding. Two Phase III trials found that apixaban was more effective for stroke prevention than either aspirin or warfarin in patients with atrial fibrillation (AF), with a similar (versus aspirin) or improved (versus warfarin) safety profile. A Phase III trial evaluating apixaban plus antiplatelet monotherapy or dual-antiplatelet therapy in patients with acute coronary syndrome ended early due to clear evidence of a clinically important increase in bleeding among patients randomized to apixaban without any meaningful reduction in ischemic events. The adverse-event profiles for apixaban and comparators have been similar in studies conducted to date.

CONCLUSION

Apixaban, a new anticoagulant, appears to offer an efficacy and safety profile comparable with that of enoxaparin for preventing VTE after orthopedic surgery, with the advantage of oral administration. In patients with AF, apixaban is more effective than either warfarin or aspirin for stroke prevention, with an acceptable safety profile.

Concomitant use of medication with antiplatelet effects in patients receiving either rivaroxaban or enoxaparin after total hip or knee arthroplasty

INTRODUCTION

The RECORD programme compared oral rivaroxaban with enoxaparin for prevention of venous thromboembolism after elective total hip or knee replacement. This analysis compared the safety of concomitant use of specified medications with rivaroxaban and enoxaparin by evaluating postoperative bleeding rates from the pooled RECORD1-4 data.

MATERIALS AND METHODS

The co-medications were non-steroidal anti-inflammatory drugs and platelet function inhibitors, including acetylsalicylic acid (no dose restriction). The endpoints evaluated were the composite of major and non-major clinically relevant bleeding and any bleeding occurring after first oral study drug intake. The time relative to surgery was stratified into three time periods: day 1-3, day 4-7 and after day 7. Relative bleeding rate ratios for co-medication use versus non-use were derived using stratified Mantel-Haenszel methods and compared between rivaroxaban and enoxaparin groups.

RESULTS

Co-medication use with rivaroxaban or enoxaparin resulted in non-significant increases in bleeding events. Respective rate ratios were not significantly different between rivaroxaban and enoxaparin for all bleeding endpoints with concomitant use of non-steroidal anti-inflammatory drugs (any bleeding, 1.22 vs 1.22; major and non-major clinically relevant bleeding, 1.28 vs 0.90) and with concomitant use of platelet function inhibitors/acetylsalicylic acid (any bleeding, 1.32 vs 1.40; major and non-major clinically relevant bleeding, 1.11 vs 1.13).

CONCLUSIONS

This explorative analysis indicates that there is no significant increase in bleeding risk for rivaroxaban compared with enoxaparin when co-administered with non-steroidal anti-inflammatory drugs or acetylsalicylic acid, although, because of low usage, the experience with platelet function inhibitors (except acetylsalicylic acid) was limited.

Aspirin- and clopidogrel-associated bleeding complications: data mining of the public version of the FDA adverse event reporting system, AERS

OBJECTIVE

Adverse event reports (AERs) submitted to the US Food and Drug Administration (FDA) were reviewed to assess the bleeding complications induced by the administration of antiplatelets and to attempt to determine the rank-order of the association.

METHODS

After a deletion of duplicated submissions and the revision of arbitrary drug names, AERs involving warfarin, aspirin, cilostazol, clopidogrel, ethyl icosapentate, limaprost alfadex, sarpogrelate, and ticlopidine were analyzed. Authorized pharmacovigilance tools were used for the quantitative detection of signals, i.e., drug-associated adverse events, including the proportional reporting ratio, the reporting odds ratio, the information component given by a Bayesian confidence propagation neural network, and the empirical Bayes geometric mean.

RESULTS

Based on 22,017,956 co-occurrences, i.e., drug-adverse event pairs, found in 1,644,220 AERs from 2004 to 2009, 736 adverse events were listed as warfarin-associated adverse events, and 147 of the 736 were bleeding complications, including haemorrhage and haematoma. Both aspirin and clopidogrel were associated with haemorrhage, but the association was more noteworthy for clopidogrel. As for bleeding complications related to the gastrointestinal system, e.g., melaena and haematochezia, the statistical metrics suggested a stronger association for aspirin than clopidogrel. The total number of co-occurrences was not large enough to compare the association with bleeding complications for the other 5 antiplatelets.

CONCLUSIONS

The data strongly suggest the necessity of well-organized clinical studies with respect to antiplatelet-associated bleeding complications.

Esophageal mucosal lesion with low-dose aspirin and prasugrel mimics malignancy: A case report

Dual antiplatelet therapy consisting of low-dose aspirin (LDA) and other antiplatelet medications is recommended in patients with coronary heart disease, but it may increase the risk of esophageal lesion and bleeding. We describe a case of esophageal mucosal lesion that was difficult to distinguish from malignancy in a patient with a history of ingesting LDA and prasugrel after implantation of a drug-eluting stent. Multiple auxiliary examinations were performed to make a definite diagnosis. The patient recovered completely after concomitant acid-suppressive therapy. Based on these findings, we strongly argue for the evaluation of the risk of gastrointestinal mucosal injury and hemorrhage if LDA therapy is required, and we stress the paramount importance of using drug combinations in individual patients.

Risk of bleeding with 2 doses of dabigatran compared with warfarin in older and younger patients with atrial fibrillation: an analysis of the randomized evaluation of long-term anticoagulant therapy (RE-LY) trial

BACKGROUND

Dabigatran 150 and 110 mg twice a day and warfarin are effective for stroke prevention in atrial fibrillation. The purpose of this study was to compare their risks of bleeding in the Randomized Evaluation of Long-Term Anticoagulant Therapy (RE-LY) trial.

METHODS AND RESULTS

The RE-LY trial randomized 18 113 patients to receive dabigatran 110 or 150 mg twice a day or warfarin dose adjusted to an international normalized ratio of 2.0 to 3.0 for a median follow-up of 2.0 years. Compared with warfarin, dabigatran 110 mg twice a day was associated with a lower risk of major bleeding (2.87% versus 3.57%; P=0.002), whereas dabigatran 150 mg twice a day was associated with a similar risk of major bleeding (3.31% versus 3.57%; P=0.32). There was a significant treatment-by-age interaction, such that dabigatran 110 mg twice a day compared with warfarin was associated with a lower risk of major bleeding in patients aged <75 years (1.89% versus 3.04%; P<0.001) and a similar risk in those aged ≥75 years (4.43% versus 4.37%; P=0.89; P for interaction <0.001), whereas dabigatran 150 mg twice a day compared with warfarin was associated with a lower risk of major bleeding in those aged <75 years (2.12% versus 3.04%; P<0.001) and a trend toward higher risk of major bleeding in those aged ≥75 years (5.10% versus 4.37%; P=0.07; P for interaction <0.001). The interaction with age was evident for extracranial bleeding, but not for intracranial bleeding, with the risk of the latter being consistently reduced with dabigatran compared with warfarin irrespective of age.

CONCLUSIONS

In patients with atrial fibrillation at risk for stroke, both doses of dabigatran compared with warfarin have lower risks of both intracranial and extracranial bleeding in patients aged <75 years. In those aged ≥75 years, intracranial bleeding risk is lower but extracranial bleeding risk is similar or higher with both doses of dabigatran compared with warfarin.

CLINICAL TRIAL REGISTRATION

http://www.clinicaltrials.gov. Unique identifier: NCT00262600.

Tissue Factor Pathway Inhibitor

Objective—

To investigate in women older than 60 whether aortic stiffness or pulse pressure (PP) is associated with selected procoagulant or anticoagulant factors and to examine whether pulsatile stretch influences these factors in human vascular smooth muscle cells (VSMCs) in vitro.

Methods and Results—

Aortic pulse wave velocity (PWV) and carotid PP were studied in 123 apparently healthy postmenopausal women. PWV, PP, von Willebrand factor, and free tissue factor pathway inhibitor (TFPI), but not mean arterial pressure, increased with age. Free TFPI and PWV were positively correlated, even after adjustment for age and PP and other confounding parameters. In vitro, 5% or 10% pulsatile stretch (at 1 Hz) enhanced TFPI synthesis and secretion by VSMCs in a time-independent manner (1 to 48 hours) without changes in protein level of smooth muscle myosin heavy chain. Application of 5% static stretch had no effect.

Conclusion—

In postmenopausal women, free TFPI increases as vascular wall function deteriorates and PP increases. These findings are supported by the increase in TFPI synthesized by VSMCs in response to cyclic stress in vitro. They suggest that VSMCs require pulsatility to interfere with the coagulation process and highlight the relevance of plasma free TFPI levels to cardiovascular diseases.

Effectiveness and safety of combined antiplatelet and anticoagulant therapy: a critical review of the evidence from randomized controlled trials

Antiplatelet and anticoagulant drugs are effective for the prevention of arterial and venous thrombosis but patients continue to experience major cardiovascular events despite their use. Strategies to improve the effectiveness of antithrombotic therapies include selecting the optimal drug and dosing regimen, the use of combinations of antiplatelet and anticoagulant drugs and the development of new more effective drugs to replace existing therapies. Evidence from randomized controlled trials indicates that the combination of aspirin and an anticoagulant is more effective than aspirin alone for the prevention of recurrent cardiovascular events in patients with acute coronary syndrome and is more effective than anticoagulation alone for the prevention of thromboembolic events in patients with mechanical heart valves, but at a cost of increased bleeding. Randomized controlled trials provide no evidence for improved effectiveness of combination therapy compared with antiplatelet therapy alone for the prevention of recurrent cardiovascular events in patients with non-cardioembolic stroke or peripheral artery disease, or compared with anticoagulant therapy alone for the prevention of stroke in patients with atrial fibrillation. Despite lack of evaluation in randomized controlled trials, combination therapy is commonly used in patients with separate indications for antiplatelet therapy (e.g., acute coronary syndrome, recent coronary artery stent) and anticoagulant therapy (e.g., atrial fibrillation with at least one additional risk factor for stroke). Randomized trials are urgently required to evaluate the effectiveness and safety of combining antiplatelet and anticoagulant therapy in these settings.

Flavonoids with an oligopolysulfated moiety: a new class of anticoagulant agents

Polysulfated (oligo)flavonoids were synthesized and assayed for their in vitro and in vivo anticoagulant activities. The approach was based on molecular hybridization of two classes of anticoagulants, sulfated polysaccharides and sulfated flavonoids. The synthesis was optimized using microwave-assisted sulfation with triethylamine-sulfur trioxide. The obtained polysulfated flavonosides were highly effective in increasing clotting times and able to completely block the clotting process, in contrast to their corresponding aglycones. The thromboelastography proved that polysulfated flavonosides possess good whole blood anticoagulation activity. The following structure-activity relationships were found: 3-O-rutinosides (10, 13) were direct inhibitors of FXa, while 7-O-rutinosides (7, 8) showed inhibition of FXa by ATIII activation. Furthermore, compounds 7 and 13 were stable in plasma and active in vivo and preliminary toxicity studies would lead us to rule out acute side effects. From the overall results, the polysulfated flavonosides showed the potential as new effective and safe agents for anticoagulant therapy.

The future of antiplatelet therapy in cardiovascular disease

Mechanisms of platelet inhibition are reviewed with emphasis on the pharmacokinetic and pharmacodynamic determinants of clinical efficacy and safety of antiplatelet drugs. Current developments in antiplatelet therapy are discussed in relation to both primary and secondary prevention of atherothrombotic complications. Interindividual variability in response to antiplatelet agents and new drug targets are outlined within the context of optimizing the balance between the cardiovascular benefits and bleeding risks of antiplatelet therapy. Recent advances in the pharmacogenetics of thienopyridines open the realistic prospect of a personalized choice of the most appropriate antiplatelet agent and tailored dose adjustment for an individual patient.

Novel factor Xa inhibitors: a patent review

IMPORTANCE OF THE FIELD

New oral anticoagulants with favorable safety profiles and fixed doses are required for the management of thromboembolism and stroke prevention in patients with atrial fibrillation. Among them, fXa inhibitors (the so-called xabans) are attractive options that can overcome limitations (e.g., bleeding) of the current oral antithrombotic therapy. The rational design of small-molecule direct fXa inhibitors, whose importance is testified by the growing number of publications and patents recently registered, has been fully supported by the X-ray crystallography of enzyme-ligand complexes.

AREAS COVERED IN THIS REVIEW

Pubmed, SciFinder Scholar, ISI web of knowledge(SM), http://ep.espacenet.com/ and Google websites were used as the main sources for literature retrieving, and > 100 patents filed between 2006 and April 2009, reviewed and discussed herein, highlight the variety among the P1 and P4 moieties on suitable scaffolds.

WHAT THE READER WILL GAIN

The replacement of the benzamidine P1 moiety, which characterizes the first generation, with less basic bioisosteric or nonpolar neutral P1 groups led to the disclosure of numerous fXa inhibitors with high potency, selectivity and oral bioavailability. Novel selective fXa inhibitors with stable pharmacokinetics, better therapeutic windows and ease-of-use than the existing anticoagulants are currently under advanced stage clinical trials.

TAKE-HOME MESSAGE

Available data from Phase II and Phase III studies reflect the drive towards fXa inhibitors as potentially more effective and safer antithrombotic drugs. Their development is expected to address two major needs for anticoagulation, namely safety and ease-of-use, and to significantly affect the anticoagulant market.

Use of anticoagulants in elderly patients: practical recommendations

Elderly people represent a patient population at high thromboembolic risk, but also at high hemorrhagic risk. There is a general tendency among physicians to underuse anticoagulants in the elderly, probably both because of underestimation of thromboembolic risk and overestimation of bleeding risk. The main indications for anticoagulation are venous thromboembolism (VTE) prophylaxis in medical and surgical settings, VTE treatment, atrial fibrillation (AF) and valvular heart disease. Available anticoagulants for VTE prophylaxis and initial treatment of VTE are low molecular weight heparins (LMWH), unfractionated heparin (UFH) or synthetic anti-factor Xa pentasaccharide fondaparinux. For long-term anticoagulation vitamin K antagonists (VKA) are the first choice and only available oral anticoagulants nowadays. Assessing the benefit-risk ratio of anticoagulation is one of the most challenging issues in the individual elderly patient, patients at highest hemorrhagic risk often being those who would have the greatest benefit from anticoagulants. Some specific considerations are of utmost importance when using anticoagulants in the elderly to maximize safety of these treatments, including decreased renal function, co-morbidities and risk of falls, altered pharmacodynamics of anticoagulants especially VKAs, association with antiplatelet agents, patient education. Newer anticoagulants that are currently under study could simplify the management and increase the safety of anticoagulation in the future.

rFVIIa and a new enhanced rFVIIa-analogue, NN1731, reduce bleeding in clopidogrel-treated and in thrombocytopenic rats

BACKGROUND

The pharmacological effect of rFVIIa occurs at the surface of activated platelets by enhancing thrombin generation at the site of vascular damage. It is therefore important to study the effects of rFVIIa in platelet-related bleeding situations. We examined the effect of rFVIIa and an rFVIIa-analogue, NN1731, on clopidogrel-induced and thrombocytopenic bleeding in rats.

METHODS AND RESULTS

Clopidogrel [10 mg kg(-1); per oral (p.o.)] severely inhibited platelet aggregation and increased blood loss after tail-transection four hours after administration. Treatment with rFVIIa (5, 10, 20 mg kg(-1)) or NN1731 (1, 5, 10 mg kg(-1)), administered five minutes after induction of bleeding, reduced blood loss significantly and dose-dependently. NN1731 had an increased hemostatic potential compared with rFVIIa, reducing blood loss to the control level, whereas this was not even achieved with the highest dose of rFVIIa. Antibody-induced thrombocytopenia reduced platelet numbers by more than 90% and increased the blood loss after tail-transection. Treatment with 10 and 20 mg kg(-1) rFVIIa significantly reduced blood loss, whereas 10 mg kg(-1) NN1731 reduced the bleeding to control levels.

CONCLUSIONS

The hemostatic effect of rFVIIa and NN1731 was demonstrated in thrombocytopenic and clopidogrel-treated rats, showing efficacy in situations with decreased platelet number or functionality. Our findings are consistent with the hypothesis that rFVIIa/NN1731 contribute to hemostasis by thrombin generation even in situations with platelet disorders. Furthermore, NN1731 demonstrated a higher hemostatic potential than rFVIIa.

Reduced factor VII and factor VIII levels and prolonged thrombin-generation times during a healthy diet in middle-aged women with mild to moderate cardiovascular disease risk

BACKGROUND

No experimental study has investigated the effect of whole-diet therapies on a wide range of hemostatic parameters, and their relationship with metabolic and inflammatory markers. Such information was sought in middle-aged women with moderate cardiovascular disease (CVD) risk subjected to an integrated healthy diet.

METHODS

Forty-nine premenopausal women were screened for C-reactive protein levels > or =1 mg L(-1) and at least one additional CVD risk factor. Sixteen women (age: 43-54 years) were selected and received a 12-week diet (four phases) integrating National Cholesterol Education Program-Adult Treatment Panel-III recommendations with components of a Mediterranean-style diet.

RESULTS

We observed a reduction in body mass index (BMI) (P = 0.001), waist circumference (P = 0.005), total (P = 0.011) and low-density lipoprotein (LDL) cholesterol levels (P = 0.035). Antigen levels of coagulation factor (F)VII (P = 0.003) and FVIII (P = 0.005) were clearly reduced by dietary intervention, which also appeared to decrease circulating tissue factor but not fibrinogen and von Willebrand factor (VWF) antigen levels. Levels of FVIII and tumor necrosis factor-alpha, among the inflammation markers, showed the highest correlation, particularly before the intervention (r = 0.55, P = 0.032). Only this cytokine influenced FVIII variation over time, thus highlighting new relations between coagulation and cellular components of inflammation. The functional effect of diet on coagulation was indicated by markedly prolonged thrombin generation initiation and propagation times (lag time, P = 0.002; time to peak, P = 0.005).

CONCLUSIONS

The changes observed in coagulation initiation and amplification phases, body composition and lipid profile could translate into a remarkable decrease in the risk for cardiovascular disease. Our observations suggest novel relationships between coagulation and inflammatory components.