| 1. |
- Becker, Richard C., et al.
(author)
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Chromogenic laboratory assays to measure the factor Xa-inhibiting properties of apixaban-an oral, direct and selective factor Xa inhibitor
- 2011
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In: Journal of Thrombosis and Thrombolysis. - : Springer Science and Business Media LLC. - 0929-5305 .- 1573-742X. ; 32:2, s. 183-187
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Journal article (peer-reviewed)abstract
- An ability to readily determine an anticoagulant effect with an emerging class of direct, active site, oral factor Xa inhibitors is viewed by the medical community as attractive and by some as an absolute requirement for their use in clinical practice. We performed a pharmacokinetic and pharmacodynamic substudy in APPRAISE-1-a study of apixaban in patients with acute coronary syndrome(ACS). A total of 1691 patients had blood sampled for apixaban plasma concentrations using mass spectrometry/high performance liquid chromatography and anti-Xa activity using a chromogenic assay employing either low molecular weight heparin or apixaban as reference standards. Anti-Xa activity, determined by either anti-Xa-LMWH (r = 0.9671; P < 0.0001) or anti-Xa-apixaban (r = 0.9669; P < 0.0001) correlated strongly and in a linear fashion with apixaban plasma concentrations. The correlations for each method were equally strong at low (< 100 ng/ml) (r = 0.86, P < 0.0001; r = 0.85, P < 0.0001), intermediate(100-200 ng/ml) (r = 0.73, P < 0.0001; r = 0.69, P < 0.0001) and high (> 200 ng/ml) (r = 0.91, P < 0.0001; r = 0.91, P < 0.0001) plasma concentrations of apixaban, respectively. Our pharmacokinetic and pharmacodynamic substudy suggests that an apixaban-mediated anticoagulant effect can be detected even at very low plasma concentrations using a standard laboratory chromogenic anti-Xa assay with either LMWH or apixaban calibrators. While establishing parameters for safety and efficacy will require further investigation, an ability to discern the presence of a drug effect may provide clinically useful information.
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| 2. |
- Becker, Richard C., et al.
(author)
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Effect of apixaban, an oral and direct factor Xa inhibitor, on coagulation activity biomarkers following acute coronary syndrome
- 2010
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In: Thrombosis and Haemostasis. - 0340-6245 .- 2567-689X. ; 104:5, s. 976-983
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Journal article (peer-reviewed)abstract
- Apixaban is an oral, direct factor Xa inhibitor under development for secondary prevention in acute coronary syndrome (ACS) Apixaban's effect on D dimer and prothrombin fragment 12 (F1 2) (coagulation activity biomarkers) was determined in a randomised, double blinded, placebo controlled phase 2 study Patients (n=1,715) with either ST segment elevation or non ST segment elevation ACS received either placebo or apixaban 2 5 mg twice daily 10 mg once daily, 10 mg twice daily or 20 mg once daily for six months Samples were obtained at baseline (before study drug administration), week 3 and week 26 Apixaban plasma concentrations were measured directly by liquid chromatography/mass spectometry and anti Xa activity was determined using apixaban as a reference standard D dimer and F 1 2 were measured using ELISA based methods Most patients had elevated D dimer and Fl 2 levels at baseline Both coagulation activity biomarkers decreased by week 3 in all treatment groups but to a greater degree with apixaban than placebo (p<0 001) In a multivariable analysis, apixaban was independently associated with a change in biomarkers over time (p<0 0001) While the overall decrease did not differ significantly among the three highest apixaban doses, Fl 2 was suppressed more rapidly by the 10 mg once daily than the 2 5 mg twice daily dose (p<0 05) There was a strong and direct relationship between apixaban plasma concentrations and anti Xa apixaban levels, and an inverse relationship for both measures with coagulation activity biomarkers In conclusion the oral direct factor Xa inhibitor apixaban significantly reduced coagulation activity biomarkers among patients with ACS The 10 mg once daily dose reduced thrombin generation (F 1 2) and fibrin formation (D dimer) more rapidly and robustly than the 25 mg twice daily dose The effect on both D dimer and F 12 was apixaban concentration and factor Xa inhibition dependent durable and provided general guidance for dose selection in phase 3 investigation.
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| 3. |
- Garcia, David A., et al.
(author)
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Apixaban versus warfarin in patients with atrial fibrillation according to prior warfarin use : Results from the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation trial
- 2013
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In: American Heart Journal. - : Elsevier BV. - 0002-8703 .- 1097-6744. ; 166:3, s. 549-558
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Journal article (peer-reviewed)abstract
- Background Patients with atrial fibrillation who are vitamin K antagonist (VKA)-naive may have a higher risk of thrombosis and/or bleeding than VKA-experienced patients. Methods and results Using data from ARISTOTLE, we assessed baseline characteristics and the treatment effect of apixaban versus warfarin in the VKA-naive and VKA-experienced cohorts. We compared rates of study drug discontinuation and time-in-therapeutic range. Overall, 7,800 (43%) were VKA naive, and 10,401 were VKA experienced. At baseline, both groups were similar with respect to age and congestive heart failure, hypertension, age, diabetes, stroke score (CHADS(2)). Fewer VKA-naive patients had a history of prior stroke (18% vs 21%) or prior bleeding (10% vs 22%) and were more often female (39% vs 33%). The effect of apixaban on the primary efficacy and safety outcomes was similar in VKA-naive (stroke/systemic embolism: hazard ratio [ HR] 0.86, 95% CI 0.67-1.11 and major bleeding: HR 0.73, 95% CI 0.59-0.91) and VKA-experienced populations (stroke/systemic embolism: HR 0.73, 95% CI 0.57-0.95, P value for interaction = 0.39 and major bleeding: HR 0.66, 95% CI 0.55-0.80, P value for interaction = 0.50). Permanent study drug discontinuation was numerically less likely in patients receiving apixaban whether they were VKA naive (HR for discontinuation: 0.87, 95% CI 0.79-0.95) or VKA experienced (HR for discontinuation: 0.93, 95% CI 0.85-1.02). Among patients receiving warfarin, the mean/median times in therapeutic range were lower in the VKA-naive group (VKA-naive: 57.5/61.4, VKA-experienced: 66.0/69.1, P < .001). Conclusion The treatment effects of apixaban (vs warfarin) were not modified by VKA naivety. The rates of stroke/systemic embolism and major bleeding were numerically lower among the patients assigned to apixaban, irrespective of prior VKA use.
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| 4. |
- Halvorsen, Sigrun, et al.
(author)
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Efficacy and safety of apixaban compared with warfarin according to age for stroke prevention in atrial fibrillation : observations from the ARISTOTLE trial
- 2014
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In: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 35:28, s. 1864-1872
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Journal article (peer-reviewed)abstract
- Aims The risk of stroke in patients with atrial fibrillation (AF) increases with age. In the ARISTOTLE trial, apixaban when compared with warfarin reduced the rate of stroke, death, and bleeding. We evaluated these outcomes in relation to patient age. Methods and results A total of 18 201 patients with AF and a raised risk of stroke were randomized to warfarin or apixaban 5 mg b.d. with dose reduction to 2.5 mg b.d. or placebo in 831 patients with >= 2 of the following criteria: age >= 80 years, body weight <= 60 kg, or creatinine >= 133 mu mol/L. We used Cox models to compare outcomes in relation to patient age during 1.8 years median follow-up. Of the trial population, 30% were <65 years, 39% were 65 to <75, and 31% were >= 75 years. The rates of stroke, all-cause death, and major bleeding were higher in the older age groups (P < 0.001 for all). Apixaban was more effective than warfarin in preventing stroke and reducing mortality across all age groups, and associated with less major bleeding, less total bleeding, and less intracranial haemorrhage regardless of age (P interaction >0.11 for all). Results were also consistent for the 13% of patients >= 80 years. No significant interaction with apixaban dose was found with respect to treatment effect on major outcomes. Conclusion The benefits of apixaban vs. warfarin were consistent in patients with AF regardless of age. Owing to the higher risk at older age, the absolute benefits of apixaban were greater in the elderly.
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| 5. |
- Lopes, Renato D., et al.
(author)
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Efficacy and safety of apixaban compared with warfarin according to patient risk of stroke and of bleeding in atrial fibrillation : a secondary analysis of a randomised controlled trial
- 2012
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In: The Lancet. - 0140-6736 .- 1474-547X. ; 380:9855, s. 1749-1758
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Journal article (peer-reviewed)abstract
- Background The Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial showed that apixaban is better than warfarin at prevention of stroke or systemic embolism, causes less bleeding, and results in lower mortality. We assessed in this trial's participants how results differed according to patients' CHADS(2), CHA(2)DS(2)VASc, and HAS-BLED scores, used to predict the risk of stroke and bleeding. Methods ARISTOTLE was a double-blind, randomised trial that enrolled 18 201 patients with atrial fibrillation in 39 countries. Patients were randomly assigned apixaban 5 mg twice daily (n=9120) or warfarin (target international normalised ratio 2.0-3.0; n=9081). The primary endpoint was stroke or systemic embolism. The primary safety outcome was major bleeding. We calculated CHADS(2), CHA(2)DS(2)VASc, and HAS-BLED scores of patients at randomisation. Efficacy analyses were by intention to treat, and safety analyses were of the population who received the study drug. ARISTOTLE is registered with ClinicalTrials.gov, number NCT00412984. Findings Apixaban significantly reduced stroke or systemic embolism with no evidence of a differential effect by risk of stroke (CHADS(2) 1, 2, or >= 3, p for interaction=0.4457; or CHA(2)DS(2)VASc 1, 2, or >= 3, p for interaction=0.1210) or bleeding (HAS-BLED 0-1, 2, or >= 3, p for interaction=0.9422). Patients who received apixaban had lower rates of major bleeding than did those who received warfarin, with no difference across all score categories (CHADS(2), p for interaction=0.4018; CHA(2)DS(2)VASc, p for interaction=0.2059; HAS-BLED, p for interaction=0.7127). The relative risk reduction in intracranial bleeding tended to be greater in patients with HAS-BLED scores of 3 or higher (hazard ratio [HR] 0.22, 95% CI 0.10-0.48) than in those with HAS-BLED scores of 0-1 (HR 0.66, 0.39-1.12; p for interaction=0.0604). Interpretation Because apixaban has benefits over warfarin that are consistent across patient risk of stroke and bleeding as assessed by the CHADS(2), CHA(2)DS(2)VASc, and HAS-BLED scores, these scores might be less relevant when used to tailor apixaban treatment to individual patients than they are for warfarin. Further improvement in risk stratification for both stroke and bleeding is needed, particularly for patients with atrial fibrillation at low risk for these events.
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