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Purpose: Low-dose rivaroxaban is often given to patients with atrial fibrillation (AF) around the world, but the rationale for its use remains unclear. We aimed to compare the efficacy and safety of standard- or low-dose rivaroxaban in patients with AF through systematic review of literature with meta-analysis. Methods: We searched PubMed, Web of Science, EMBASE, Clinical Trials.gov, the Cochrane Library, and Bayer trial website from inception of each database until June 2020. Randomized controlled trials (RCTs) and cohort studies were included in the meta-analysis. A random-effects model was employed to calculate the pooled effect estimates. Results: Two RCTs and 17 cohort studies were included in the qualitative analysis. Indirect comparison of RCTs showed no significant difference between the two rivaroxaban dosages in risk of efficacy or safety outcomes (p > 0.05). Indirect comparison of cohort studies showed a lower risk of MACE among Caucasians in standard-dose group (HR 0.779; 95% CI 0.687–0.884; p < 0.001). Bleeding outcomes did not differ significantly between the two dosage regimens in Asian or Caucasian populations, except that the standard dose was associated with higher risk of major bleeding among elderly Caucasian patients (HR 1.329; 95% CI 1.141–1.547; p < 0.001). The quality of evidence was rated ranging from very low to low for all the efficacy and safety outcomes. Conclusion: In Caucasians with AF, standard-dose rivaroxaban may prevent MACE significantly better than low-dose treatment. Further studies in Asians are needed to verify the advantages of the standard dose. [ABSTRACT FROM AUTHOR]

Background: For patients taking factor Xa (FXa) inhibitors who have life-threatening bleeding, emergency surgery, drug interactions, etc., a rapid and precise assay is needed to monitor for potential medication failure, to assess safety during periprocedural anticoagulation management, and to manage the care of chronically anticoagulated patients. Anti-factor Xa (anti-Xa) activity assays have been recommended in guidelines, but the evaluation of different calibrations of anti-Xa activity assays and the data on the recommended range are still limited, especially in the Asian population. Methods: This is a nationwide multicenter methodology exploratory study in an Asian population, including nine hospitals from Beijing, Shanghai, Liaoning, Shandong, Jiangsu, Anhui, Henan, Chongqing, and Fujian. A total of 485 healthy volunteers and 219 patients taking rivaroxaban or apixaban (single dose) were enrolled in the study. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS) was employed to detect plasma rivaroxaban and apixaban. The prothrombin time (PT), activated partial thromboplastin time (APTT), and levels of anti-Xa activity were tested as pharmacodynamic parameters in plasma samples. We evaluated the correlation of anti-Xa activity and blood concentration via HPLC-MS, and then compared the two methods of target drug-calibrated and low-molecular-weight heparin (LMWH)-antithrombin–calibrated anti-Xa activity. Correlations between variables were examined using Pearson's correlation analysis. Logistic regression was applied to evaluate significant differences in anti-Xa activity and blood concentration, using models adjusted by baseline characteristics. Results: The results suggested anti-Xa activity had better correlation with blood concentrations of apixaban and rivaroxaban than APTT and PT (p < 0.001). Target drug-calibrated anti-Xa activity had better correlation with HPLC-MS results at every dose level and blood collection time (p < 0.001). The expected concentrations (ng/mL) derived from rivaroxaban-calibrated assays of rivaroxaban 10 mg, 15 mg, and 20 mg were about 210, 330, and 270 at peak concentrations, and 28, 44, and 58, respectively, at the trough concentrations. Conclusions: In this study, we confirm that target drug calibration of anti-Xa activity is a better quantitative detection method for oral direct FXa inhibitors than LMWH-calibrated anti-Xa activity in clinical practice, and expected peak–trough levels are recommended for the Asian population. [ABSTRACT FROM AUTHOR]

Background: Due to the high risk of ischemic and arterial or venous bleeding events in atrial fibrillation (AF) or venous thromboembolism (VTE) patients with renal impairment (RI), selection of appropriate anticoagulant regimen is important. Therefore, we systematically reviewed and compared the safety and effects of oral anticoagulants in AF and VTE patients with RI. Methods: Eligible articles were identified through a literature search in PubMed, Embase, ClinicalTrials.gov, and the Cochrane Library for studies published between January 2008 and November 2020. Network meta-analysis was conducted with STATA 14.0 to analyze the effects and safety of each drug with regard to different levels of renal function. Results: 15 studies including 82,931 patients (76,957 with AF and 5974 with VTE) were analyzed. Compared with those of warfarin, the risk ratios of effect and safety outcomes of apixaban were 0.70 (95% confidence interval [CI] 0.60–0.82) and 0.56 (95% CI 0.42–0.76) in AF patients and 0.33 (95% CI 0.19–0.59) and 0.95 (95% CI 0.68–1.34) in VTE patients. Apixaban had the first or second highest probability of being ranked first with respect to surface under the cumulative ranking curve (SUCRA) scores in the prevention of major bleeding events, while in the prevention of ischemic events, rivaroxaban showed a higher SUCRA score (0.78–0.92) in mild RI patients and dabigatran showed a higher SUCRA value (0.90–0.99) in moderate RI patients. Conclusions and Relevance: In the systematic review and meta-analysis, for AF or VTE patients with RI, direct oral anticoagulants performed comparably to or better than warfarin with regard to safety and effects. The network meta-analysis indicated that for patients with mild RI, apixaban might be safer for patients with a lower risk of ischemic events, while rivaroxaban might be suitable for patients with a lower risk of bleeding events. For patients with moderate RI, apixaban could reduce the risk of ischemic events without increasing the risk of bleeding events. For AF patients with severe RI, apixaban, rivaroxaban, and warfarin showed a similar effect. These results might provide suggestions for clinical arterial and venous thrombosis prevention. [ABSTRACT FROM AUTHOR]

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT • Rivaroxaban is an oral, direct Factor Xa inhibitor in advanced clinical development for the prevention and treatment of thromboembolic disorders. • In single- and multiple-dose Phase I studies in White subjects, rivaroxaban was safe and demonstrated predictable, dose-dependent pharmacokinetics and pharmacodynamics. WHAT THIS STUDY ADDS • The Phase III programme with rivaroxaban is being conducted worldwide. • Therefore, it is necessary to determine whether the pharmacokinetics, pharmacodynamics and tolerability of rivaroxaban are altered in patients of different ethnic origins. • Dose-escalation studies were conducted to determine the safety, pharmacokinetics and pharmacodynamics of single and multiple doses of rivaroxaban in healthy Chinese subjects. AIMS To investigate the safety, pharmacokinetics and pharmacodynamics of rivaroxaban, an oral, direct Factor Xa (FXa) inhibitor, in healthy, male Chinese subjects. METHODS Two randomized, single-blind, placebo-controlled, dose-escalation studies were conducted in healthy Chinese men aged 18–45 years. In the single-dose study, subjects received single, oral doses of rivaroxaban 2.5, 5, 10, 20 and 40 mg. In the multiple-dose study, oral rivaroxaban was administered in doses of 5, 10, 20 and 30 mg twice daily for 6 days. RESULTS Rivaroxaban, in single and multiple doses up to 60 mg, was well tolerated. Rapid absorption was observed in both studies (time to Cmax 1.25–2.5 h). In the multiple-dose study, rivaroxaban exposure increased dose-proportionally after the first dose and at steady state (for the 5–20-mg doses). The half-life of rivaroxaban was up to 7.9 h in the single-dose study. Maximal inhibition of FXa activity was achieved within 1–3 h of dosing in the single-dose study [at 20 mg FXa inhibition as a median percentage change from baseline, 45.92; 95% confidence interval (CI) 44.64, 50.70] and 2–3 h after administration at steady state in the multiple-dose study (at 20 mg median FXa inhibition as a median percentage change from baseline, 60.25; 95% CI 56.16, 63.05), in line with maximum rivaroxaban plasma concentrations. CONCLUSIONS Rivaroxaban demonstrated predictable pharmacokinetics and pharmacodynamics in healthy Chinese subjects, in line with findings observed previously in White subjects. This suggests that fixed doses of rivaroxaban may be administered to all patients, regardless of their ethnic origin. [ABSTRACT FROM AUTHOR]