ximelagatran and Embolism

Chronic anticoagulation with vitamin K antagonists (VKAs) prevents ischaemic stroke and systemic embolism in people with non-valvular atrial fibrillation (AF) but dose adjustment, coagulation monitoring and bleeding limits its use. Direct thrombin inhibitors (DTIs) are under investigation as potential alternatives.. To assess (1) the comparative efficacy of long-term anticoagulation using DTIs versus VKAs on vascular deaths and ischaemic events in people with non-valvular AF, and (2) the comparative safety of chronic anticoagulation using DTIs versus VKAs on (a) fatal and non-fatal major bleeding events including haemorrhagic strokes, (b) adverse events other than bleeding and ischaemic events that lead to treatment discontinuation and (c) all-cause mortality in people with non-valvular AF.. We searched the Cochrane Stroke Group Trials Register (July 2013), the Cochrane Central Register of Controlled Trials (CENTRAL), (The Cochrane Library, May 2013), MEDLINE (1950 to July 2013), EMBASE (1980 to October 2013), LILACS (1982 to October 2013) and trials registers (September 2013). We also searched the websites of clinical trials and pharmaceutical companies and handsearched the reference lists of articles and conference proceedings.. Randomised controlled trials (RCTs) comparing DTIs versus VKAs for prevention of stroke and systemic embolism in people with non-valvular AF.. All three review authors independently performed data extraction and assessment of risk of bias. Primary analyses compared all DTIs combined versus warfarin. We performed post hoc analyses excluding ximelagatran because this drug was withdrawn from the market owing to safety concerns.. We included eight studies involving a total of 27,557 participants with non-valvular AF and one or more risk factors for stroke; 26,601 of them were assigned to standard doses groups and included in the primary analysis. The DTIs: dabigatran 110 mg twice daily and 150 mg twice daily (three studies, 12,355 participants), AZD0837 300 mg once per day (two studies, 233 participants) and ximelagatran 36 mg twice per day (three studies, 3726 participants) were compared with the VKA warfarin (10,287 participants). Overall risk of bias and statistical heterogeneity of the studies included were low.The odds of vascular death and ischaemic events were not significantly different between all DTIs and warfarin (odds ratio (OR) 0.94, 95% confidence interval (CI) 0.85 to 1.05). Sensitivity analysis by dose of dabigatran on reduction in ischaemic events and vascular mortality indicated that dabigatran 150 mg twice daily was superior to warfarin although the effect estimate was of borderline statistical significance (OR 0.86, 95% CI 0.75 to 0.99). Sensitivity analyses by other factors did not alter the results. Fatal and non-fatal major bleeding events, including haemorrhagic strokes, were less frequent with the DTIs (OR 0.87, 95% CI 0.78 to 0.97). Adverse events that led to discontinuation of treatment were significantly more frequent with the DTIs (OR 2.18, 95% CI 1.82 to 2.61). All-cause mortality was similar between DTIs and warfarin (OR 0.91, 95% CI 0.83 to 1.01).. DTIs were as efficacious as VKAs for the composite outcome of vascular death and ischaemic events and only the dose of dabigatran 150 mg twice daily was found to be superior to warfarin. DTIs were associated with fewer major haemorrhagic events, including haemorrhagic strokes. Adverse events that led to discontinuation of treatment occurred more frequently with the DTIs. We detected no difference in death from all causes.

Topics: Amidines; Antithrombins; Atrial Fibrillation; Azetidines; Benzimidazoles; Benzylamines; beta-Alanine; Dabigatran; Drug Administration Schedule; Embolism; Female; Humans; Male; Randomized Controlled Trials as Topic; Safety-Based Drug Withdrawals; Stroke; Vitamin K; Warfarin

For the last decades vitamin K antagonists have been the most effective anticoagulant treatment of atrial fibrillation. New molecules are being designed, mainly due to the great amount of disadvantages in the management of conventional anticoagulation. Dabigatran, rivaroxaban and apixaban will soon be available as an alternative to warfarin/acenocumarol. All of them have demonstrated to be non-inferior to warfarin in preventing stroke and systemic embolism, with even dabigatran 150 mg bid and apixaban being superior. They have also a lower risk of bleeding, especially regarding severe/fatal and intracranial hemorrhages. This is a real revolution. The advance of these new anticoagulants will be limited only by the higher cost, and will progressively become the protagonists of oral anticoagulation in patients with nonvalvular atrial fibrillation.

Topics: Administration, Oral; Anticoagulants; Atrial Fibrillation; Azetidines; Benzimidazoles; Benzylamines; beta-Alanine; Dabigatran; Embolism; Humans; Morpholines; Pyrazoles; Pyridines; Pyridones; Rivaroxaban; Stroke; Thiazoles; Thiophenes; Treatment Outcome; Warfarin

Unfractionated heparin, derived from porcine intestine, is the prototype of a rapidly acting anticoagulant. It has been used for over 60 years to arrest or prevent thrombus growth. Low-molecular-weight heparins, available in the last 20 years, are manufactured from unfractionated heparin and have superior dose-response relationships because of fewer nonspecific reactions with plasma proteins and cells. Fondaparinux is a recently approved five-saccharide synthetic molecule that carries the evolution of heparin further. It is a pure Xa inhibitor, with minimal nonspecific interactions. It does not appear to elicit the antibody that leads to heparin-induced thrombocytopenia (HIT). All of these agents are given either intravenously or subcutaneously. They act indirectly by activating the natural plasma inhibitor, antithrombin III. Direct thrombin inhibitors bind directly to thrombin's active site without interaction with the cofactor, antithrombin III. Lepirudin (Refludan; Berlex, Wayne, NJ) and argatroban (Argatroban; GlaxoSmithKline, Research Triangle Park, NC) are given intravenously and are usually used in HIT and thrombosis associated with HIT. Bivalirudin (Angiomax; The Medicines Company, Parsippany, NJ) is a parenteral direct thrombin used in place of heparin in percutaneous coronary interventions. Ximelagatran (Exanta; AstraZeneca, Wilmington, DE) is an oral direct thrombin inhibitor under development for both acute and chronic anticoagulation.

Topics: Anticoagulants; Arginine; Azetidines; Benzylamines; Embolism; Enzyme Inhibitors; Fondaparinux; Heparin; Heparin, Low-Molecular-Weight; Hirudins; Humans; Peptide Fragments; Pipecolic Acids; Polysaccharides; Recombinant Proteins; Sulfonamides; Thrombin; Thrombocytopenia; Venous Thrombosis

Atrial fibrillation is the most frequently encountered tachyarrhythmia requiring therapy. Treatment issues include therapy for any reversible cause; the identification and treatment of any underlying structural disorder; control of the ventricular rate, both for symptom reduction and prevention of tachycardic-induced cardiomyopathy; restoration and maintenance of sinus rhythm when symptoms persist despite rhythm control; and anticoagulation in patients with high-risk markers for systemic embolization: age over 65 years, hypertension, diabetes, ventricular failure, rheumatic valvular disease, and prior stroke or other embolic event. In such patients, anticoagulation with warfarin is currently recommended. Warfarin therapy carries significant risks (especially bleeding), inconveniences (the cost of prothrombin time monitoring, the need for rigid dietary stability, the concerns of drug and herbal interactions), and other concerns (the issue of generic formulation substitution).. Under development are oral thrombin inhibitors. The first to reach clinical approval will likely be ximelagatran. In clinical trials to date, ximelagatran has proven to be equal to or superior to warfarin in the prevention and treatment of thrombophlebitis. In atrial fibrillation patients, the Stroke Prevention Using Oral Thrombin Inhibitor in Atrial Fibrillation (SPORTIF) trials completed so far appear to show a similar or better efficacy for ximelagatran versus warfarin as regards both prevention of embolic events and lower risks of major bleeding, with no serious adverse effects except for apparently reversible alterations in liver function tests in approximately 6% of subjects, all occurring early in therapy to date. If the remaining SPORTIF trial (SPORTIF V) is confirmatory (results to be available in late 2003), it is expected that this exciting new product will be submitted this winter to the Food and Drug Administration for approval. Recent findings also include the observations in the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) and Rate Control Versus Electrical Cardioversion (RACE) trials that anticoagulation should not be discontinued despite the restoration and maintenance of sinus rhythm.. Oral direct thrombin inhibitors, such as ximelagatran, appear likely to replace the use of warfarin in most patients in the near future, because of a better risk-benefit profile.

Topics: Administration, Oral; Anticoagulants; Atrial Fibrillation; Azetidines; Benzylamines; Clinical Trials as Topic; Embolism; Fibrinolytic Agents; Humans; Prothrombin Time; Randomized Controlled Trials as Topic; Stroke; Venous Thrombosis; Warfarin

Thrombin is a central bioregulator of coagulation and is therefore a key target in the therapeutic prevention and treatment of thromboembolic disorders, including deep vein thrombosis and pulmonary embolism. The current mainstays of anticoagulation treatment are heparins, which are indirect thrombin inhibitors, and coumarins, such as warfarin, which modulate the synthesis of vitamin K-dependent proteins. Although efficacious and widely used, heparins and coumarins have limitations because their pharmacokinetics and anticoagulant effects are unpredictable, with the risk of bleeding and other complications resulting in the need for close monitoring with their use. Low-molecular-weight heparins (LMWHs) provide a more predictable anticoagulant response, but their use is limited by the need for subcutaneous administration. In addition, discontinuation of heparin treatment can result in a thrombotic rebound due to the inability of these compounds to inhibit clot-bound thrombin. Direct thrombin inhibitors (DTI) are able to target both free and clot-bound thrombin. The first to be used was hirudin, but DTIs with lower molecular weights, such as DuP 714, PPACK, and efegatran, have subsequently been developed, and these agents are better able to inhibit clot-bound thrombin and the thrombotic processes that take place at sites of arterial damage. Such compounds inhibit thrombin by covalently binding to it, but this can result in toxicity and nonspecific binding. The development of reversible noncovalent DTIs, such as inogatran and melagatran, has resulted in safer, more specific and predictable anticoagulant treatment. Oral DTIs, such as ximelagatran, are set to provide a further breakthrough in the prophylaxis and treatment of thrombosis.

Topics: Administration, Oral; Amino Acid Chloromethyl Ketones; Anticoagulants; Arginine; Azetidines; Benzylamines; Binding Sites; Biological Availability; Blood Coagulation; Comorbidity; Coumarins; Drug Design; Embolism; Female; Forecasting; Glycine; Guanidines; Heart Diseases; Hemorrhage; Heparin; Heparin, Low-Molecular-Weight; Hirudin Therapy; Humans; Neoplasms; Pipecolic Acids; Pregnancy; Pregnancy Complications, Hematologic; Prodrugs; Safety; Serine; Stroke; Sulfonamides; Thrombin; Thrombophilia; Thrombosis

Warfarin prevents stroke in atrial fibrillation (AF); however, concerns regarding international normalized ratio control and hemorrhage limit its use in the elderly. The oral direct thrombin inhibitors (DTIs) are potential alternatives to warfarin, offering fixed dosing without drug and dietary interactions and the need for international normalized ratio monitoring. Although ximelagatran, a DTI studied in the Stroke Prevention using an ORal Thrombin Inhibitor in atrial Fibrillation trials, has been withdrawn, development of other DTIs continues. We report our experience in elderly high-risk AF patients on ximelagatran compared with warfarin therapy.. Data from patients with AF and stroke risk factors randomized in Stroke Prevention using an ORal Thrombin Inhibitor in atrial Fibrillation III and V trials to ximelagatran or warfarin were analyzed for stroke/systemic emboli, bleeding, and raised alanine aminotransferase levels in those >or=75 (n=2804) and <75 (n=4525) years.. Ximelagatran was as effective as warfarin in reducing stroke/systemic emboli in the elderly (2.23%/y with ximelagatran vs 2.27%/y with warfarin) as in younger patients (1.25%/y vs 1.28%/y). Total bleeds were significantly lower with ximelagatran compared with warfarin in elderly (40% vs 45%, P=0.01) and younger (27% vs 35%, P<0.001) patients. Raised alanine aminotransferase values (>3-fold elevation) among ximelagatran patients were more common in older (7.5% old vs 5.3% young) patients, particularly women (9.5% elderly women vs 6.1% elderly men).. In high-risk elderly AF patients, ximelagatran is as effective as warfarin with less bleeding, but alanine aminotransferase elevations are common, particularly in elderly women. Oral DTIs for stroke prevention show promise in elderly patients.

Topics: Administration, Oral; Age Factors; Aged; Aged, 80 and over; Alanine Transaminase; Anticoagulants; Atrial Fibrillation; Azetidines; Benzylamines; Cerebral Hemorrhage; Double-Blind Method; Embolism; Female; Humans; Intracranial Thrombosis; Male; Middle Aged; Sex Characteristics; Sex Factors; Stroke; Thrombin; Treatment Outcome; Up-Regulation; Warfarin

To show results of a prespecified pooled analysis of the studies SPORTIF III (open-label) and SPORTIF V (double-blind), to assess the homogeneity of the results and to explore subgroup analyses and adverse events.. 7,329 patients with atrial fibrillation (AF) and >or=1 additional stroke risk factor were randomized to warfarin (international normalized ratio 2.0-3.0) or ximelagatran (36 mg twice daily). Over 11,346 patient-years (mean 18.5 months/patient), 184 patients developed primary events of stroke and systemic embolism (ximelagatran 1.62 vs. warfarin 1.65%/year; p = 0.94). Heterogeneity between trials with respect to the primary event rate (study-by-treatment interaction p = 0.026) was found. This could not be explained statistically by baseline patient characteristics or by treatment (except perhaps by the better anticoagulation with warfarin in SPORTIF V) and was not evident for secondary end-points. There was no conclusive difference in major bleeding rates (ximelagatran 1.88 vs. warfarin 2.46%/year; p = 0.054), but combined minor plus major bleeding was lower with ximelagatran (31.7 vs. 38.7%/year; p < 0.0001). Elevation of liver enzymes occurred more frequently in patients taking ximelagatran (6.1% vs. warfarin 0.8%; p < 0.0001) and was reversible except in rare cases.. Fixed-dose oral ximelagatran without coagulation monitoring prevented stroke and systemic embolism as effectively as warfarin in patients with AF. Differences in the results of the two trials might relate to consistency of warfarin anticoagulation, different degree of blinding in the two trials, other concomitant therapies or chance. Further investigation is required to explore the long-term safety profile of ximelagatran.

Topics: Administration, Oral; Adult; Aged; Aged, 80 and over; Anticoagulants; Atrial Fibrillation; Azetidines; Benzylamines; Embolism; Female; Humans; Male; Middle Aged; Randomized Controlled Trials as Topic; Risk Factors; Stroke; Thrombin; Warfarin

Aspirin is used in combination with anticoagulant therapy in patients with atrial fibrillation (AF), but evidence of additional efficacy is not available.. We compared ischemic events and bleeding in the SPORTIF III and IV randomized trials of anticoagulation with warfarin (international normalized ratio 2-3) or fixed-dose ximelagatran. Low-dose aspirin (<100 mg/d) was allowed based on prevailing guidelines.. The 14% of patients receiving aspirin more often had diabetes (27.5% vs 23%, P < .01), coronary artery disease (69% vs 41%, P < .01), previous stroke or transient ischemic attack (26% vs 20%, P < .01), and left ventricular dysfunction (41% vs 36%, P < .01). Addition of aspirin to either warfarin or ximelagatran was associated with no reduction in stroke or systemic embolism. Major bleeding occurred significantly more often with aspirin plus warfarin (3.9% per year) than with warfarin alone (2.3% per year, P < .01), aspirin plus ximelagatran (2.0% per year), or ximelagatran alone (1.9% per year). The rate of myocardial infarction with aspirin and warfarin (0.6% per year) was not significantly different from that with ximelagatran alone (1.0% per year), warfarin alone (1.0% per year), or aspirin and ximelagatran (1.4% per year).. Aspirin combined with anticoagulant therapy was associated with no reduction in stroke, systemic embolism, or myocardial infarction in patients with AF. Aspirin combined with warfarin was associated with an incremental rate of major bleeding of 1.6% per year. No increased major bleeding occurred with aspirin and ximelagatran. These results suggest that the risks associated with addition of aspirin to anticoagulation in patients with AF outweigh the benefit.

Topics: Aged; Anticoagulants; Aspirin; Atrial Fibrillation; Azetidines; Benzylamines; Drug Therapy, Combination; Embolism; Female; Hemorrhage; Humans; Male; Middle Aged; Myocardial Infarction; Myocardial Ischemia; Platelet Aggregation Inhibitors; Randomized Controlled Trials as Topic; Risk Assessment; Stroke; Treatment Outcome; Warfarin

Atrial fibrillation (AF) causes 50,000 to 100,000 ischemic strokes annually in the U.S., most of which could be prevented by oral anticoagulant treatment of the highest-risk patients. The greatest barrier to such treatment is the narrow therapeutic index of the vitamin K antagonists ([VKAs]: warfarin and related coumarin derivatives), the only oral anticoagulant agents currently available. Safe and effective treatment with the VKAs requires careful monitoring, because they interact with many other drugs and foods, and their anticoagulant action is unpredictable. Besides vitamin K, candidate targets for anticoagulant therapy include thrombin, a key prothrombotic mediator. Ximelagatran, the oral direct thrombin inhibitor at the most advanced stage of clinical development, is rapidly absorbed and bioconverted to its active moiety, melagatran-a potent, competitive inhibitor of both free and clot-bound thrombin. Two large clinical trials have demonstrated that fixed-dose oral ximelagatran, 36 mg twice daily, administered without coagulation monitoring, prevents stroke and systemic embolic events in patients with nonvalvular AF as effectively as well-controlled, adjusted-dose warfarin (international normalized ratio 2.0 to 3.0). The overall risk of bleeding was lower with ximelagatran than warfarin, although differences in rates of major hemorrhage were not statistically significant. Elevation of serum alanine aminotransferase levels above 3x the upper limit of normal occurred in approximately 6% of ximelagatran-treated patients but typically returned toward pretreatment levels without associated symptoms. In terms of preventing thromboembolism without hemorrhage, ximelagatran may have a more favorable benefit:risk profile than warfarin for patients with AF.

Topics: Administration, Oral; Alanine Transaminase; Animals; Anticoagulants; Atrial Fibrillation; Azetidines; Benzylamines; Dose-Response Relationship, Drug; Embolism; Humans; Randomized Controlled Trials as Topic; Stroke; Thrombin

Topics: Atrial Fibrillation; Azetidines; Benzylamines; Embolism; Humans; Randomized Controlled Trials as Topic; Warfarin

Ximelagatran is a novel oral direct thrombin inhibitor that offers a number of advantages over the standard treatment, warfarin, in patients with atrial fibrillation. Two large clinical trials, one open-label (Stroke Prevention Using Oral Thrombin Inhibitor in Atrial Fibrillation [SPORTIF] III), one double-blind (SPORTIF V), have compared the efficacy and safety of fixed-dose ximelagatran without anticoagulation monitoring with dose-adjusted warfarin using a non-inferiority design. On the basis of the results, the investigators concluded that ximelagatran was just as effective as warfarin in preventing stroke or systemic embolism (the primary end point), because the pre-specified non-inferiority criterion was met. Reanalysis of the data with rather conservative interpretive criteria, however, revealed a number of deficiencies: 1) an unreasonably generous margin that was potentially biased toward non-inferiority, given the low baseline event rate of warfarin; 2) the inappropriateness of the analytical method used to estimate the non-inferiority margin; 3) a lack of confidence that ximelagatran retains at least 50% of warfarin's effect (a prerequisite to the establishment of non-inferiority); 4) significant heterogeneity in the magnitude of efficacy observed in the two trials; and 5) safety concerns regarding increased liver toxicity with ximelagatran without a significant offsetting advantage in major bleeding. This imbalance in the benefit-risk profile materially undermines the investigators' claim of non-inferiority of ximelagatran and led the Food and Drug Administration to reject the sponsor's application for ximelagatran. Despite published conclusions to the contrary, we conclude that ximelagatran has not been shown to be non-inferior to warfarin. Such determinations of non-inferiority are highly dependent on the underlying assumptions, and graphical sensitivity analyses make this dependence explicit.

Topics: Anticoagulants; Azetidines; Bayes Theorem; Benzylamines; Embolism; Humans; Meta-Analysis as Topic; Randomized Controlled Trials as Topic; Research Design; Risk Assessment; Sample Size; Stroke; Treatment Outcome; Warfarin

Topics: Advisory Committees; Anticoagulants; Atrial Fibrillation; Azetidines; Benzylamines; Chemical and Drug Induced Liver Injury; Drug Approval; Embolism; Humans; Randomized Controlled Trials as Topic; Stroke; United States; United States Food and Drug Administration; Venous Thrombosis