vitamin-k-semiquinone-radical and ximelagatran

Cancer increases the risk of thromboembolic events, especially in people receiving anticoagulation treatments.. To compare the efficacy and safety of low molecular weight heparins (LMWHs), direct oral anticoagulants (DOACs) and vitamin K antagonists (VKAs) for the long-term treatment of venous thromboembolism (VTE) in people with cancer.. We conducted a literature search including a major electronic search of the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 1), MEDLINE (Ovid), and Embase (Ovid); handsearching conference proceedings; checking references of included studies; use of the 'related citation' feature in PubMed and a search for ongoing studies in trial registries. As part of the living systematic review approach, we run searches continually, incorporating new evidence after it is identified. Last search date 14 May 2018.. Randomized controlled trials (RCTs) assessing the benefits and harms of long-term treatment with LMWHs, DOACs or VKAs in people with cancer and symptomatic VTE.. We extracted data in duplicate on study characteristics and risk of bias. Outcomes included: all-cause mortality, recurrent VTE, major bleeding, minor bleeding, thrombocytopenia, and health-related quality of life (QoL). We assessed the certainty of the evidence at the outcome level following the GRADE approach (GRADE handbook).. Of 15,785 citations, including 7602 unique citations, 16 RCTs fulfilled the eligibility criteria. These trials enrolled 5167 people with cancer and VTE.Low molecular weight heparins versus vitamin K antagonistsEight studies enrolling 2327 participants compared LMWHs with VKAs. Meta-analysis of five studies probably did not rule out a beneficial or harmful effect of LMWHs compared to VKAs on mortality up to 12 months of follow-up (risk ratio (RR) 1.00, 95% confidence interval (CI) 0.88 to 1.13; risk difference (RD) 0 fewer per 1000, 95% CI 45 fewer to 48 more; moderate-certainty evidence). Meta-analysis of four studies did not rule out a beneficial or harmful effect of LMWHs compared to VKAs on major bleeding (RR 1.09, 95% CI 0.55 to 2.12; RD 4 more per 1000, 95% CI 19 fewer to 48 more, moderate-certainty evidence) or minor bleeding (RR 0.78, 95% CI 0.47 to 1.27; RD 38 fewer per 1000, 95% CI 92 fewer to 47 more; low-certainty evidence), or thrombocytopenia (RR 0.94, 95% CI 0.52 to 1.69). Meta-analysis of five studies showed that LMWHs probably reduced the recurrence of VTE compared to VKAs (RR 0.58, 95% CI 0.43 to 0.77; RD 53 fewer per 1000, 95% CI 29 fewer to 72 fewer, moderate-certainty evidence).Direct oral anticoagulants versus vitamin K antagonistsFive studies enrolling 982 participants compared DOACs with VKAs. Meta-analysis of four studies may not rule out a beneficial or harmful effect of DOACs compared to VKAs on mortality (RR 0.93, 95% CI 0.71 to 1.21; RD 12 fewer per 1000, 95% CI 51 fewer to 37 more; low-certainty evidence), recurrent VTE (RR 0.66, 95% CI 0.33 to 1.31; RD 14 fewer per 1000, 95% CI 27 fewer to 12 more; low-certainty evidence), major bleeding (RR 0.77, 95% CI 0.38 to 1.57, RD 8 fewer per 1000, 95% CI 22 fewer to 20 more; low-certainty evidence), or minor bleeding (RR 0.84, 95% CI 0.58 to 1.22; RD 21 fewer per 1000, 95% CI 54 fewer to 28 more; low-certainty evidence). One study reporting on DOAC versus VKA was published as abstract so is not included in the main analysis.Direct oral anticoagulants versus low molecular weight heparinsTwo studies enrolling 1455 participants compared DOAC with LMWH. The study by Raskob did not rule out a beneficial or harmful effect of DOACs compared to LMWH on mortality up to 12 months of follow-up (RR 1.07, 95% CI 0.92 to 1.25; RD 27 more per 1000, 95% CI 30 fewer to 95 more; low-certainty evidence). The data also showed that DOACs may have shown a likely reduction in VTE recurrence up to 12 months. For the long-term treatment of VTE in people with cancer, evidence shows that LMWHs compared to VKAs probably produces an important reduction in VTE and DOACs compared to LMWH, may likely reduce VTE but may increase risk of major bleeding. Decisions for a person with cancer and VTE to start long-term LMWHs versus oral anticoagulation should balance benefits and harms and integrate the person's values and preferences for the important outcomes and alternative management strategies.Editorial note: this is a living systematic review (LSR). LSRs offer new approaches to review updating in which the review is continually updated, incorporating relevant new evidence as it becomes available. Please refer to the Cochrane Database of Systematic Reviews for the current status of this review.

Topics: Administration, Oral; Anticoagulants; Azetidines; Benzimidazoles; Benzylamines; beta-Alanine; Dabigatran; Hemorrhage; Heparin, Low-Molecular-Weight; Humans; Neoplasms; Oligosaccharides; Randomized Controlled Trials as Topic; Venous Thromboembolism; Vitamin K

This study was designed to compare efficacy and safety among novel oral anticoagulants (NOACs), which have not been directly compared in randomized control trials to date.. We performed network meta-analyses of randomized control trials in preventing thromboembolic events and major bleeding in patients with atrial fibrillation. PubMed, Embase, and the Cochrane Database of Systematic Reviews for published studies and various registries of clinical trials for unpublished studies were searched for 2002-2013. All phase III randomized controlled trials (RCTs) of NOACs (apixaban, edoxaban, dabigatran, rivaroxaban), idraparinux, and ximelagatran were reviewed.. A systematic literature search identified nine phase III RCTs for primary analyses. The efficacy of each NOAC was similar with respect to our primary composite endpoint following adjustment for open label designs [odds ratios (ORs) versus vitamin K antagonists: apixaban 0.79; dabigatran 150mg 0.77; edoxaban 60mg 0.87; rivaroxaban 0.86] except for dabigatran 110mg and edoxaban 30mg. Apixaban and edoxaban 30mg and 60mg had significantly fewer major bleeding events than dabigatran 150mg, ricvaroxaban, and vitamin K antagonists. All NOACs were similar in reducing secondary endpoints with the exception of dabigatran 110mg and 150mg which were associated with a significantly greater incidence of myocardial infarction compared to apixaban, edoxaban 60mg, and rivaroxaban.. Our indirect comparison with adjustment for study design suggests that the efficacy of the examined NOACs is similar across drugs, but that some differences in safety and risk of myocardial infarction exist, and that open label study designs appear to overestimate safety and treatment efficacy. Differences in study design should be taken into account in the interpretation of results from RCTs of NOACs.

Topics: Administration, Oral; Aged; Aged, 80 and over; Anticoagulants; Atrial Fibrillation; Azetidines; Benzylamines; Dabigatran; Hemorrhage; Humans; Myocardial Infarction; Odds Ratio; Oligosaccharides; Pyrazoles; Pyridines; Pyridones; Randomized Controlled Trials as Topic; Rivaroxaban; Stroke; Thiazoles; Thromboembolism; Treatment Outcome; Vitamin K

Despite widespread adoption of acetylsalicylic acid and P2Y12 receptor inhibitor therapy as the standard of care for secondary event prevention in patients with acute coronary syndrome (ACS), the rate of cardiovascular death or myocardial infarction following discharge is approximately 24-31% over five years, indicating an important unmet need to reduce further the risk of recurrent ACS events. Because thrombin has a role in arterial thrombus generation, a mechanistic rationale exists for adding an anticoagulant to dual antiplatelet therapy to reduce cardiovascular event rates and mortality. The direct thrombin inhibitor dabigatran and the direct Factor Xa inhibitors rivaroxaban and apixaban have been investigated for this application, with only rivaroxaban successfully completing a phase III trial. These results suggest that dose selection is of paramount importance in this indication, with lower anticoagulant doses (relative to those used in other indications, such as stroke prevention in atrial fibrillation) plus low-dose acetylsalicylic acid potentially improving cardiovascular outcomes. This article reviews clinical trial data of anticoagulants for secondary event prevention in patients with ACS; it also discusses the mechanistic reasons that may underlie these observations and looks towards the potential impact of findings from the ATLAS ACS 2 TIMI 51 trial on clinical practice.

Topics: Acute Coronary Syndrome; Administration, Oral; Anticoagulants; Azepines; Azetidines; Benzamides; Benzimidazoles; Benzylamines; beta-Alanine; Dabigatran; Humans; Morpholines; Pyrazoles; Pyridones; Rivaroxaban; Thiophenes; Thrombin; Vitamin K

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

Cancer increases the risk of thromboembolic events in patients including those receiving anticoagulation treatments.. To compare the efficacy and safety of low molecular weight heparin (LMWH) and oral anticoagulants for the long-term treatment of venous thromboembolism (VTE) in patients with cancer.. We conducted a comprehensive search for studies of anticoagulation in cancer patients including 1. a February 2013 electronic search of: the Cochrane Central Register of Controlled Trials (CENTRAL Issue 12, 2012), MEDLINE, and EMBASE; 2. a handsearch of conference proceedings; 3. checking of references of included studies; 4. use of the 'related citation' feature in PubMed; and 5. a search of clinicaltrials.gov for ongoing studies.. We included randomized controlled trials (RCTs) comparing long-term treatment with LMWH versus oral anticoagulants (vitamin K antagonist (VKA) or ximelagatran) in patients with cancer and symptomatic objectively confirmed VTE.. Using a standardized data form, we extracted data on methodological quality, participants, interventions and outcomes of interest: survival, recurrent VTE, major bleeding, minor bleeding, thrombocytopenia, and postphlebitic syndrome. We assessed the quality of evidence at the outcome level following the GRADE approach.. Of 9559 identified citations, 10 RCTs (11 reports) were eligible and reported data for 1981 patients with cancer. We excluded 14 studies in which patients with cancer constituted study subgroups, but did not report outcome data for them. Meta-analysis of seven RCTs comparing LMWH with VKA found no statistically significant survival benefit (hazard ratio (HR) 0.96; 95% confidence interval (CI) 0.81 to 1.14) but a statistically significant reduction in VTE (HR 0.47; 95% CI 0.32 to 0.71). The remaining findings did not exclude a beneficial or harmful effect of LMWH compared with VKA for the outcomes of major bleeding (RR 1.07; 95% CI 0.52 to 2.19), minor bleeding (RR 0.89; 95% CI 0.51 to 1.55), or thrombocytopenia (RR 0.98; 95% CI 0.57 to 1.66). We judged the quality of evidence as low for mortality, major bleeding, and minor bleeding, and as moderate for recurrent VTE.One RCT comparing dabigatran with VKA did not exclude beneficial or harmful effects of one agent over the other. One RCT comparing six months' extension of anticoagulation with 18 months of ximelagatran 24 mg twice daily versus no extended ximelagatran did not exclude beneficial or harmful effects for the outcomes of reduction in VTE, mortality, and minor bleeding. One RCT comparing once-weekly subcutaneous injection of idraparinux for three or six months versus standard treatment (parenteral anticoagulation followed by warfarin or acenocoumarol) suggested a reduction in recurrent VTE (HR 0.39; 95% CI 0.14 to 1.11) at six months, but did not exclude beneficial or harmful effects for the outcomes of mortality (HR 0.99; 95% CI 0.66 to 1.48) and major bleeding (RR 1.04; 95% CI 0.39 to 2.83).. For the long-term treatment of VTE in patients with cancer, LMWH compared with VKA reduces venous thromboembolic events but not mortality. The decision for a patient with cancer and VTE to start long-term LMWH versus oral anticoagulation should balance the benefits and harms and integrate the patient's values and preferences for the important outcomes and alternative management strategies.

Topics: Administration, Oral; Anticoagulants; Azetidines; Benzimidazoles; Benzylamines; beta-Alanine; Dabigatran; Heparin, Low-Molecular-Weight; Humans; Neoplasms; Oligosaccharides; Randomized Controlled Trials as Topic; Venous Thromboembolism; Vitamin K

The vitamin K antagonists (VKA) available for stroke prevention in patients with atrial fibrillation have many drawbacks due to their difficult clinical use and high risk of bleeding. Currently, several drugs are being developed as possible substitutes for VKA that have many advantages such as the lack of monitoring requirement and scarce pharmacologic and food interactions. The present article provides an update on the new oral anticoagulants that are in a more advanced stage of clinical research, their pharmacologic properties, advantages and disadvantages and their results in recent clinical trials.

Topics: Administration, Oral; Anticoagulants; Azetidines; Benzimidazoles; Benzylamines; beta-Alanine; Clinical Trials as Topic; Dabigatran; Drug Monitoring; Drugs, Investigational; Hemorrhage; Humans; Morpholines; Multicenter Studies as Topic; Patient Care Planning; Pyrazoles; Pyridones; Randomized Controlled Trials as Topic; Rivaroxaban; Stroke; Thiophenes; Thrombophilia; Vitamin K

To assess whether the combined analysis of all phase III trials of nonvitamin-K-antagonist (non-VKA) oral anticoagulants in patients with atrial fibrillation and previous stroke or transient ischemic attack shows a significant difference in efficacy or safety compared with warfarin.. We searched PubMed until May 31, 2012, for randomized clinical trials using the following search items: atrial fibrillation, anticoagulation, warfarin, and previous stroke or transient ischemic attack. Studies had to be phase III trials in atrial fibrillation patients comparing warfarin with a non-VKA currently on the market or with the intention to be brought to the market in North America or Europe. Analysis was performed on intention-to-treat basis. A fixed-effects model was used as more appropriate than a random-effects model when combining a small number of studies.. Among 47 potentially eligible articles, 3 were included in the meta-analysis. In 14 527 patients, non-VKAs were associated with a significant reduction of stroke/systemic embolism (odds ratios, 0.85 [95% CI, 074-0.99]; relative risk reduction, 14%; absolute risk reduction, 0.7%; number needed to treat, 134 over 1.8-2.0 years) compared with warfarin. Non-VKAs were also associated with a significant reduction of major bleeding compared with warfarin (odds ratios, 0.86 [95% CI, 075-0.99]; relative risk reduction, 13%; absolute risk reduction, 0.8%; number needed to treat, 125), mainly driven by the significant reduction of hemorrhagic stroke (odds ratios, 0.44 [95% CI, 032-0.62]; relative risk reduction, 57.9%; absolute risk reduction, 0.7%; number needed to treat, 139).. In the context of the significant limitations of combining the results of disparate trials of different agents, non-VKAs seem to be associated with a significant reduction in rates of stroke or systemic embolism, hemorrhagic stroke, and major bleeding when compared with warfarin in patients with previous stroke or transient ischemic attack.

Topics: Administration, Oral; Anticoagulants; Atrial Fibrillation; Azetidines; Benzylamines; Clinical Trials, Phase III as Topic; Humans; Ischemic Attack, Transient; Randomized Controlled Trials as Topic; Stroke; Vitamin K; Warfarin

Patients who have undergone total hip or knee replacement (THR, TKR) have a high risk of developing venous thromboembolism (VTE) following surgery, despite appropriate anticoagulation with warfarin or low molecular weight heparin (LMWH). New anticoagulants are under investigation.. To examine the efficacy and safety of prophylactic anticoagulation with direct thrombin inhibitors (DTIs) versus LMWH or vitamin K antagonists in the prevention of VTE in patients undergoing THR or TKR.. The Cochrane Peripheral Vascular Disease Group searched their Specialized Register (last searched 12 March 2010) and CENTRAL (last searched 2010, Issue 2).. Randomised controlled trials.. Three reviewers independently assessed methodological quality and extracted data in pre-designed tables. The reported follow-up events were included. We included 14 studies included involving 21,642 patients evaluated for efficacy and 27,360 for safety. No difference was observed in major VTE in DTIs compared with LMWH in both types of operations (odds ratio (OR) 0.91; 95% confidence interval (CI) 0.69 to 1.19), with high heterogeneity (I(2) 71%). No difference was observed with warfarin (OR 0.85; 95% CI 0.63 to 1.15) in TKR, with no heterogeneity (I(2) 0%).More total bleeding events were observed in the DTI group (in ximelagatran and dabigatran but not in desirudin) in patients subjected to THR (OR 1.40; 95% CI 1.06, 1.85; I(2) 41%) compared with LMWH. No difference was observed with warfarin in TKR (OR 1.76; 95% CI 0.91 to 3.38; I(2) 0%). All-cause mortality was higher in the DTI group when the reported follow-up events were included (OR 2.06; 95% CI 1.10 to 3.87).Studies that initiated anticoagulation before surgery showed less VTE events; those that began anticoagulation after surgery showed more VTE events in comparison with LMWH. Therefore, the effect of the DTIs compared with LMWH appears to be influenced by the time of initiation of coagulation more than the effect of the drug itself.The results obtained from sensitivity analysis, did not differ from the analysed results; this strengthens the value of the results.. Direct thrombin inhibitors are as effective in the prevention of major venous thromboembolism in THR or TKR as LMWH and vitamin K antagonists. However, they show higher mortality and cause more bleeding than LMWH. No severe hepatic complications were reported in the analysed studies. Use of ximelagatran is not recommended for VTE prevention in patients who have undergone orthopedic surgery. More studies are necessary regarding dabigatran.

Topics: Anticoagulants; Antifibrinolytic Agents; Arthroplasty, Replacement, Hip; Arthroplasty, Replacement, Knee; Azetidines; Benzimidazoles; Benzylamines; Contraindications; Dabigatran; Heparin, Low-Molecular-Weight; Humans; Pyridines; Randomized Controlled Trials as Topic; Thrombin; Venous Thromboembolism; Vitamin K; Warfarin

Because 1.1 million myocardial infarctions occur in the United States alone each year, and 450,000 of them are recurrent infarctions, which carry an inherently greater risk of death and disability than first events, the importance of secondary prevention strategies that can be implemented widely is unparalleled in health care. Antithrombotic therapies, both antiplatelet and anticoagulant, have become the mainstays of these strategies. This article covers the use of chronic antiplatelet and anticoagulation agents after myocardial infarction. It does not include the management of these patients in the acute phase.

Topics: Anticoagulants; Aspirin; Azetidines; Benzylamines; Clopidogrel; Humans; Myocardial Infarction; Peripheral Vascular Diseases; Platelet Activation; Platelet Aggregation Inhibitors; Randomized Controlled Trials as Topic; Recurrence; Risk Factors; Thrombolytic Therapy; Thrombosis; Ticlopidine; Vitamin K; Warfarin

Cancer increases the risk of thromboembolic events and the risk of recurrent thromboembolic events while on anticoagulation.. To compare the efficacy and safety of low molecular weight heparin (LMWH) and oral anticoagulants (vitamin K antagonist (VKA) and ximelagatran) for the long term treatment of venous thromboembolism (VTE) in patients with cancer.. A comprehensive search was undertaken including a January 2007 search of electronic databases; Cochrane Central Register of Controlled Trials (CENTRAL), (The Cochrane Library 2007, Issue 1). MEDLINE (1966 onwards; accessed via OVID), EMBASE (1980 onwards; accessed via OVID) and ISI the Web of Science. Hand search of the proceedings of the American Society of Clinical Oncology and of the American Society of Hematology. Checking of references of included studies, relevant papers and related systematic reviews. Use of "related article" feature in PubMed; and (5) search of ISI the Web of Science for papers citing landmark studies.. Randomized controlled trials (RCTs) comparing long term treatment with LMWH versus oral anticoagulants (VKA or ximelagatran) in patients with cancer and symptomatic objectively confirmed VTE.. Using a standardized data form we extracted data on methodological quality, participants, interventions and outcomes of interest: survival, recurrent VTE, major bleeding, minor bleeding, thrombocytopenia and postphlebitic syndrome.. Of 3986 identified citations, eight RCTs were eligible and reported data for patients with cancer. Their overall methodological quality was moderate. Meta-analysis of six RCTs showed that LMWH, compared to VKA provided no statistically significant survival benefit (Hazard ratio (HR) = 0.96; 95% CI 0.81 to 1.14) but a statistically significant reduction in VTE (HR = 0.47; 95% (Confidence Interval (CI) = 0.32 to 0.71). There was no statistically significant difference between LMWH and VKA in bleeding outcomes (RR = 0.91; 95% CI = 0.64 to 1.31) or thrombocytopenia (RR = 1.02; 95% CI = 0.60 to 1.74). One RCT compared tinzaparin and dalteparin and showed no differences in the outcomes of interest. One RCT compared a six months extension of anticoagulation with 18 months Ximelagatran 24mg twice daily versus placebo. It showed a reduction in VTE (HR = 0.16; 95% CI 0.09 to 0.30) with no apparent effect on survival or bleeding.. For the long term treatment of VTE in patients with cancer, LMWH compared to VKA reduces venous thromboembolic events but not death. The decision for a patient with cancer and VTE to start long term LMWH versus oral anticoagulation should balance the benefits and downsides and integrate the patient's values and preferences for the important outcomes and alternative management strategies.

Topics: Anticoagulants; Azetidines; Benzylamines; Heparin, Low-Molecular-Weight; Humans; Neoplasms; Randomized Controlled Trials as Topic; Venous Thromboembolism; Vitamin K

Chronic, nonvalvular atrial fibrillation occurs more frequently with increasing age, together with an increasing risk for ischemic stroke. Guidelines recommend oral anticoagulation with a vitamin K antagonist for patients >65 years without risk factors and patients <65 years with risk factors for cardiac diseases. Advancing age also increases the risk for bleeding complications under oral anticoagulants; thus, only a part of these patients receives anticoagulant therapy. The risk of falls in elderly patients is of advancing relevance for this therapeutic decision. Oral direct thrombin inhibitors like ximelagatran may be an alternative choice for therapy. Ischemic strokes and systemic embolism in the same frequency with 2x36 mg ximelagatran over 18 months (91/3664 patients: 1.6%/year, for study Sportif III and Sportif V) compared with warfarin (93/3665 patients: 1.6%/year for study Sportif III and Sportif V). All bleeding complications occurred less frequently under therapy with ximelagatran. This could be of importance for elderly patients with risk factors for bleeding or risk of falling.

Topics: Administration, Oral; Anticoagulants; Atrial Fibrillation; Azetidines; Benzylamines; Cerebral Infarction; Clinical Trials as Topic; Hemorrhage; Humans; Risk Factors; Thromboembolism; Vitamin K; Warfarin

Topics: Anticoagulants; Azetidines; Benzylamines; Clinical Trials as Topic; Humans; Prodrugs; Stroke; Venous Thrombosis; Vitamin K

The oral direct thrombin inhibitor ximelagatran is the first oral anticoagulant since the introduction of the vitamin K antagonists in the early 1940s. A comparison of the discovery and early clinical development of the two classes of oral anticoagulants reveals some similarities but also several differences that illustrate the change in drug discovery over the last half century.

Topics: Animals; Anticoagulants; Azetidines; Benzylamines; Blood Coagulation; Cattle; Clinical Trials as Topic; Drug Design; Hemorrhage; History, 20th Century; Humans; Melilotus; Thrombin; Vitamin K; Warfarin

Nonvalvular atrial fibrillation (AF) is an independent risk factor for stroke that becomes increasingly prevalent as populations age. More than half a dozen clinical trials have demonstrated that anticoagulation with the vitamin K antagonist warfarin is the most effective therapy for stroke prophylaxis in AF. The narrow therapeutic index of warfarin requires that the intensity of anticoagulation be maintained within the international normalized ratio (INR) range of 2.0 to 3.0 to optimize efficacy while minimizing bleeding risk. The pharmacokinetics of warfarin are subject to variability due to interactions with multiple drugs and foods, making maintenance of the INR within this range difficult to achieve in clinical practice without close coagulation monitoring and frequent dose adjustments. Current guidelines recommend oral anticoagulation for high-risk individuals with AF but these inherent limitations lead to substantial underprescribing, particularly in elderly patients at greatest risk. This has stimulated the development of new agents with improved benefit-risk profiles, such as ximelagatran, the first of the oral direct thrombin inhibitors, which has a wider therapeutic margin and low potential for drug interactions, allowing fixed dosing without anticoagulation monitoring. Ximelagatran has been evaluated for stroke prevention in AF in the Stroke Prevention using an Oral Direct Thrombin Inhibitor in Atrial Fibrillation (SPORTIF) program, the largest clinical trials of antithrombotic therapy for stroke prevention in AF to date. The phase III trials of ximelagatran in AF, SPORTIF III and V, found a fixed oral dose of ximelagatran (36 mg twice daily) comparable to dose-adjusted warfarin (INR 2.0 to 3.0) in preventing stroke and systemic thromboembolic complications among high-risk patients with AF. Results from the population of over 7000 patients in SPORTIF III and V demonstrate noninferiority of ximelagatran compared with warfarin. Data from SPORTIF III show an absolute reduction in stroke and systemic embolic events with ximelagatran compared with warfarin of 1.6% per year versus 2.3% per year, respectively ( P = 0.10). SPORTIF V further supports noninferiority between the two agents with an absolute risk reduction of 0.45%, well within the predefined noninferiority margin (95% confidence interval -0.13, 1.03; P = 0.13). Although event rates for major bleeding did not differ significantly with ximelagatran versus warfarin in either study, combined

Topics: Anticoagulants; Atrial Fibrillation; Azetidines; Benzylamines; Chemical and Drug Induced Liver Injury; Hemorrhage; Humans; Risk Assessment; Stroke; Thrombin; Vitamin K; Warfarin

Vitamin K antagonists belong to the group of most frequently used drugs worldwide. They are used for long-term anticoagulation therapy, and exhibit their anticoagulant effect by inhibition of vitamin K epoxide reductase. Each drug exists in two different enantiomeric forms and is administered orally as a racemate. The use of vitamin K antagonists is complicated by a narrow therapeutic index and an unpredictable dose-response relationship, giving rise to frequent bleeding complications or insufficient anticoagulation. These large dose response variations are markedly influenced by pharmacokinetic aspects that are determined by genetic, environmental and possibly other yet unknown factors. Previous knowledge in this regard principally referred to warfarin. Cytochrome P450 (CYP) 2C9 has clearly been established as the predominant catalyst responsible for the metabolism of its more potent S-enantiomer. More recently, CYP2C9 has also been reported to catalyse the hydroxylation of phenprocoumon and acenocoumarol. However, the relative importance of CYP2C9 for the clearance of each anticoagulant substantially differs. Overall, the CYP2C9 isoenzyme appears to be most important for the clearance of warfarin, followed by acenocoumarol and, lastly, phenprocoumon. The less important role of CYP2C9 for the clearance of phenprocoumon is due to the involvement of CYP3A4 as an additional catalyst of phenprocoumon hydroxylation and significant excretion of unchanged drug in bile and urine, while the elimination of warfarin and acenocoumarol is almost completely by metabolism. Consequently, the effects of CYP2C9 polymorphisms on the pharmacokinetics and anticoagulant response are also least pronounced in the case of phenprocoumon; this drug seems preferable for therapeutic anticoagulation in poor metabolisers of CYP2C9. In addition to these vitamin K antagonists, oral thrombin inhibitors are currently under clinical development for the prevention and treatment of thromboembolism. Of these, ximelagatran has recently gained marketing authorisation in Europe. These novel drugs all feature some major advantages over traditional anticoagulants, including a wide therapeutic interval, the lack of anticoagulant effect monitoring and a low drug-drug interaction potential. However, they are also characterised by some pitfalls. Amendments of traditional anticoagulant therapy, including self-monitoring of international normalised ratio values or prospective genotyping for individual d

Topics: Acenocoumarol; Animals; Anticoagulants; Aryl Hydrocarbon Hydroxylases; Azetidines; Benzylamines; Cytochrome P-450 CYP2C9; Humans; Hydroxylation; Mixed Function Oxygenases; Phenprocoumon; Polymorphism, Genetic; Thrombin; Vitamin K; Vitamin K Epoxide Reductases; Warfarin

Anticoagulation is highly effective in the prevention and treatment of venous thromboembolism (VTE). Since decades, vitamin K antagonists (VKA) were the only available oral anticoagulants. Even though VKA are very effective, they have numerous practical problems: Due to their narrow therapeutic window, highly variable dose requirements and drug interactions, close monitoring is mandatory, aiming towards an INR of 2-3 for most indications. At present, new oral anticoagulants are being studied, such as the oral direct thrombin inhibitor Ximelagatran, which in trials for prevention and treatment of VTE appears at least equivalent to heparin and VKA. Heparins have to be administered parenterally, and low molecular-weight heparins have been able to overcome some of the shortcomings of standard heparins, such as limited bioavailability, variable dose response and heparin induced thrombocytopenia (HIT). Heparinoids and hirudins are alternative anticoagulants to treat HIT. With the development of synthetic pentasaccharides, such as Fondaparinux an increase in efficacy could be achieved in high-risk thromboprophylaxis.

Topics: Anticoagulants; Azetidines; Benzylamines; Dose-Response Relationship, Drug; Drug Therapy; Evidence-Based Medicine; Fondaparinux; Heparin; Humans; Patient Care Management; Polysaccharides; Practice Patterns, Physicians'; Thrombocytopenia; Treatment Outcome; Venous Thrombosis; Vitamin K

Topics: Anticoagulants; Azetidines; Benzylamines; Clinical Trials, Phase III as Topic; Drug Design; Factor Xa Inhibitors; Follow-Up Studies; Fondaparinux; Humans; Polysaccharides; Randomized Controlled Trials as Topic; Recurrence; Thromboembolism; Thrombophilia; Venous Thrombosis; Vitamin K

Topics: Azetidines; Benzylamines; Fibrinolytic Agents; Heparin, Low-Molecular-Weight; Humans; Orthopedic Procedures; Postoperative Complications; Therapeutic Equivalency; Thromboembolism; Venous Thrombosis; Vitamin K

Thrombin has long been a target for development of oral anticoagulants but it has been difficult to find synthetic inhibitors with a desirable combination of pharmacodynamic and pharmacokinetic properties. However, there are now two oral direct thrombin inhibitors (DTIs) in clinical development, ximelagatran (ExantaTM) and BIBR 1048. Both are prodrugs with two protecting groups that are eliminated after absorption from the gastrointestinal tract. Their main active substances, melagatran and BIBR 953, are both potent and selective DTIs. In experimental models of thrombosis, melagatran has been shown to have a shallower dose-response curve than warfarin and, therefore, a better separation between efficacy and bleeding. Oral bioavailability, measured as the plasma concentration of the active metabolite, seems to be higher for ximelagatran (20%) than for BIBR 1048 (estimated to 5%). BIBR 953 has a longer half-life (about 12 h) than does melagatran (3-5 h) after oral administration of BIBR 1048 and ximelagatran, respectively. Both melagatran and BIBR 953 are mainly eliminated via the renal route. The variability of the plasma concentration of melagatran after oral administration of ximelagatran is low. There are no clinically relevant interactions with food or cytochrome P450 metabolized drugs and ximelagatran. In clinical studies, ximelagatran has been administered in a twice-daily fixed-dose regimen without coagulation monitoring. Results of published clinical studies are encouraging, both with regard to efficacy and bleeding. Major indications in Phase III studies with ximelagatran are the prevention of venous thromboembolism (VTE) in hip and knee replacement surgery, treatment and long-term secondary prevention of VTE and prevention of stroke in patients with nonvalvular atrial fibrillation. It is anticipated that with a favourable outcome of the Phase III clinical studies new oral DTIs, with the oral fixed-dose regimen without routine coagulation monitoring, will ease the use of today's anticoagulant therapy.

Topics: Anticoagulants; Azetidines; Benzimidazoles; Benzylamines; Dabigatran; Glycine; Hemostasis; Humans; Prodrugs; Pyridines; Stroke; Thrombin; Thrombosis; Venous Thrombosis; Vitamin K

Anticoagulants are widely used for the prevention and treatment of venous and arterial thrombosis. Current treatment strategies often employ a combination of parenteral and oral agents because the only available orally active anticoagulants, vitamin K antagonists, have a delayed onset of action. Furthermore, vitamin K antagonists have a narrow therapeutic window that necessitates careful anticoagulation monitoring, and dosing is problematic because of multiple food and drug interactions. These limitations highlight the need for oral anticoagulants that produce a more predictable anticoagulant response than vitamin K antagonists, thereby obviating the need for laboratory monitoring. Ximelagatran has the potential to meet this need. A prodrug of melagatran, an agent that targets thrombin, ximelagatran exhibits many of the characteristics of an ideal anticoagulant. This article (1). reviews the limitations of vitamin K antagonists, (2). lists the characteristics of an ideal anticoagulant, (3). rationalizes thrombin as a target for new anticoagulants, (4). reviews the preclinical and clinical data with ximelagatran, and (5). provides clinical perspective as to the future of ximelagatran and other orally active anticoagulants currently under development.

Topics: Administration, Oral; Anticoagulants; Atrial Fibrillation; Azetidines; Benzylamines; Blood Coagulation; Drug Monitoring; Glycine; Humans; International Normalized Ratio; Postoperative Complications; Prodrugs; Stroke; Thrombin; Thrombosis; Venous Thrombosis; Vitamin K

AZD0837 and ximelagatran are oral direct thrombin inhibitors that are rapidly absorbed and bioconverted to their active forms, AR-H067637 and melagatran, respectively. This study investigated the antithrombotic effect of AZD0837, compared to ximelagatran and the vitamin K antagonist (VKA) phenprocoumon (Marcoumar), in a disease model of thrombosis in patients with non-valvular atrial fibrillation (NVAF).. Open, parallel-group studies were performed in NVAF patients treated with VKA, which was stopped aiming for an international normalized ratio (INR) of ≤ 2 before randomization. Study I: 38 patients randomized to AZD0837 (150,250 or 350 mg) or ximelagatran 36 mg twice daily for 10-14 days. Study II: 27 patients randomized to AZD0837 250 mg twice daily or VKA titrated to an INR of 2-3 for 10-14 days. A control group of 20 healthy elderly subjects without NVAF or anticoagulant treatment was also studied. Size of thrombus formed on pig aorta strips was measured after a 5-minute perfusion at low shear rate with blood from the patient/control subject.. Thrombus formation was inhibited by AZD0837 and ximelagatran. Relative to untreated patients, a 50% reduction of thrombus size was estimated at plasma concentrations of 0.6 and 0.2 μmol/L for AR-H067637 and melagatran, respectively. For patients receiving VKA treatment, the thrombus size was about 15% lower compared with healthy elderly controls.. Effects of AZD0837 and ximelagatran on thrombus formation were similar or greater than for VKA therapy and correlated with plasma concentrations of their active forms.

Topics: Administration, Oral; Aged; Amidines; Animals; Anticoagulants; Antithrombins; Atrial Fibrillation; Azetidines; Benzylamines; Female; Humans; In Vitro Techniques; Male; Middle Aged; Swine; Thrombosis; Treatment Outcome; Vitamin K

Topics: Anticoagulants; Atrial Fibrillation; Azetidines; Benzylamines; Canada; Double-Blind Method; Hemorrhage; Humans; Risk; Stroke; Thrombin; Treatment Outcome; United States; Vitamin K; Warfarin

The effectiveness of oral anticoagulation therapy with warfarin (a vitamin K antagonist) in the treatment of thromboembolic disease, including stroke prophylaxis in patients with atrial fibrillation is well recognised. However, warfarin has a narrow therapeutic window and an unpredictable anticoagulation response, which make it difficult to achieve and maintain optimal anticoagulation. Various dietary factors, including sudden changes in eating patterns, can significantly alter anticoagulation control, thereby potentially exposing patients to the risk of bleeding or thromboembolic complications. Dietary vitamin K intake is a particularly important factor, given the mechanism of action of warfarin. Areas covered: In this article, we cover the sources of vitamin K and their potential effect of dietary vitamin K on anticoagulation response to warfarin. We also discuss the results of studies on the effect of vitamin K supplementation on anticoagulation stability. Expert commentary: A stable dietary vitamin K, promoted by daily oral vitamin K supplementation, can improve anticoagulation stability in patients on warfarin therapy. There is experimental evidence in animals that dietary vitamin K affects anticoagulation response to the direct thrombin inhibitor, ximelagatran. Whether dietary vitamin K affects anticoagulation response to the currently licensed direct oral anticoagulants (DOACs) in man remains to be investigated.

Topics: Administration, Oral; Animals; Anticoagulants; Atrial Fibrillation; Azetidines; Benzylamines; Diet; Dietary Supplements; Food-Drug Interactions; Hemorrhage; Humans; Stroke; Thromboembolism; Vitamin K; Warfarin

Topics: Administration, Oral; Anticoagulants; Azetidines; Benzylamines; Humans; Models, Molecular; Morpholines; Rivaroxaban; Terminology as Topic; Thiophenes; Vitamin K

Dietary vitamin K is known to influence the anticoagulation response to warfarin. It is possible that dietary vitamin K availability also influences the pharmacological activity of other oral anticoagulants, which target the vitamin-K dependent clotting proteins in the coagulation cascade. This study examined whether vitamin K insufficiency affected anticoagulation response to the direct thrombin inhibitor, ximelagatran. Anticoagulation response to ximelagatran and warfarin in rats on a normal diet was compared to those on a vitamin K deficient diet. Ximelagatran and warfarin increased prothrombin time (PT) by 1.4- and 1.3-fold, activated partial thromboplastin time (APTT) by 1.8- and 1.4-fold and ecarin clotting time (ECT) by 6.8- and 1.2-fold, respectively, in rats on normal diet. Vitamin K deficient diet alone caused modest increases in PT, APTT and ECT. The anticoagulant activity of both ximelagatran and warfarin was significantly greater in rats on vitamin K deficient diet (6.1- and 12.3-fold for PT, 2.6- and 5.1-fold for APTT and 2.9- and 1.6-fold for ECT, respectively) compared to those on normal diet. Factor II activity was reduced by both ximelagatran (58%) and warfarin (44%) in rats on normal diet. However, factor II activity was virtually abolished (<0.1%) by both drugs in rats on vitamin K deficient diet. The results suggest that oral anticoagulant drugs, whose primary site of action is not within the vitamin K cycle, may also exhibit variability in clinical response due to dietary variation as the established coumarin drugs such as warfarin.

Topics: Animals; Anticoagulants; Azetidines; Benzylamines; Enzyme Inhibitors; Male; Rats; Rats, Wistar; Thrombin; Vitamin K; Vitamin K Deficiency

Topics: Administration, Oral; Animals; Anticoagulants; Azetidines; Benzylamines; Biological Availability; Blood Coagulation; Drug Design; Factor Xa Inhibitors; Food-Drug Interactions; Humans; Rats; Thrombin; Vitamin K; Vitamin K Deficiency

Several new oral anticoagulants are currently investigated in phase III programmes, mainly with inhibition of factor Xa or thrombin as their pharmacological target. Advantages are expected with these new drugs compared with vitamin K antagonists, but one potential drawback is the lack of specific antidotes. During the clinical studies with ximelagatran, an oral direct thrombin inhibitor withdrawn due to hepatic side effects, investigators were instructed to manage bleedings with routine measures. We have retrospectively tried to assess whether this was sufficient or whether there was a need for reversal strategies. The study population consisted of patients with major bleedings in three long-term studies (104 ximelagatran, 155 warfarin). All individual patient narratives were reviewed with respect to management of the bleeding. Complementary data were retrieved from the data-based case report forms. Approximately, two of three of the patients in both groups were subject to some kind of treatment. One-third (1/3) in both groups had transfusions documented and/or received specific medication. Vitamin K was given more often to warfarin patients. Two ximelagatran patients received prothrombin complex (four-factor concentrate), but one was a patient with a severe hepatopathy suspected to be drug-induced. Overall, the case descriptions did not reveal any apparent differences in the course of events between groups. We found no indications that the lack of an antidote posed a clinical problem in patients treated with ximelagatran as compared with warfarin. The relatively short half-life of melagatran, the active metabolite of ximelagatran, may have contributed to these results.

Topics: Adult; Aged; Aged, 80 and over; Anticoagulants; Azetidines; Benzylamines; Blood Transfusion; Disease Management; Female; Hemorrhage; Humans; Male; Middle Aged; Retrospective Studies; Thrombin; Treatment Outcome; Vitamin K; Warfarin

Anticoagulant therapy plays an important role in current medical practice. The main types of anticoagulant agents are: heparins, hirudins and vitamin K antagonists. None of the drugs used as anticoagulants meet the criteria of an ideal anticoagulant because they have side effects and they interact with other compounds. The main side effect of anticoagulant therapy is bleeding. The choice of a certain anticoagulant is made by the doctor based on the clinical context and also on the desired effect.

Topics: Anticoagulants; Azetidines; Benzylamines; Fondaparinux; Hemorrhage; Heparin; Hirudins; Humans; International Normalized Ratio; Polysaccharides; Thrombocytopenia; Vitamin K; Warfarin

Topics: Anticoagulants; Azetidines; Benzylamines; Chemical and Drug Induced Liver Injury; Clinical Trials as Topic; Humans; Myocardial Infarction; Thrombin; Thrombosis; Vitamin K; Warfarin

Topics: Anticoagulants; Aspirin; Atrial Fibrillation; Azetidines; Benzylamines; Drug Therapy, Combination; Humans; Prodrugs; Randomized Controlled Trials as Topic; Stroke; Thromboembolism; Treatment Outcome; Vitamin K; Warfarin

The new oral direct thrombin inhibitor ximelagatran is at least equivalent to warfarin for stroke prevention in patients with non-valvar atrial fibrillation, and seems to be a promising adjunct to aspirin after acute coronary syndrome

Topics: Administration, Oral; Anticoagulants; Antithrombins; Azetidines; Benzylamines; Humans; Thrombosis; Vitamin K; Warfarin