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Examining therapeutic equivalence between branded and generic warfarin in Brazil: The WARFA crossover randomized controlled trial.
Gomes Freitas, C, Walsh, M, Coutinho, EL, Vincenzo de Paola, AA, Atallah, ÁN
PloS one. 2021;(4):e0248567
Abstract
OBJECTIVES To determine whether the generic and branded warfarins used as anticoagulants in Brazil are therapeutic equivalents based on their international normalized ratio (INR) results. METHODS This crossover randomized controlled trial had four periods. We used the branded Marevan and two generic versions of warfarin sodium tablets, manufactured by União Química and Teuto laboratories, all purchased from retail drugstores. Eligible participants were outpatients from an anticoagulation clinic at a university hospital in São Paulo, Brazil. They had atrial fibrillation or flutter and had been using warfarin for at least 2 months with an INR therapeutic range of 2.0-3.0. Randomization was by numbered, opaque, sealed envelopes. Healthcare personnel and outcome assessors were blinded to treatments, but patients were not. The primary outcome was the variability in the INR (ΔINR) and secondary outcomes included mean INR. We accepted formulations as equivalent if the 95% confidence interval (CI) of the comparison of ΔINR between branded and generic formulations was within the limit of ±0.49. RESULTS One hundred patients were recruited and randomized to six sequences of treatment (four sequences with n = 17 and two sequences with n = 16). União Química generic warfarin had equivalent variability in the INR to Marevan (ΔINR +0.09 [95% CI -0.29 to +0.46], n = 84). Comparison between Teuto generic warfarin and Marevan was inconclusive (ΔINR +0.29 [95% CI -0.09 to +0.68], n = 84). CONCLUSIONS Marevan and União Química warfarin had equivalent therapeutic effectiveness and both could be confidently used for anticoagulation. The comparison between Marevan and TW was inconclusive and does not warrant a statement of equivalence. Our methods are especially important for comparing generic and branded drugs that raise concerns and may be subject of future investigations by regulatory agents. TRIAL REGISTRATION ClinicalTrials.gov NCT02017197.
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Rivaroxaban vs Warfarin Sodium in the Ultra-Early Period After Atrial Fibrillation-Related Mild Ischemic Stroke: A Randomized Clinical Trial.
Hong, KS, Kwon, SU, Lee, SH, Lee, JS, Kim, YJ, Song, TJ, Kim, YD, Park, MS, Kim, EG, Cha, JK, et al
JAMA neurology. 2017;(10):1206-1215
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IMPORTANCE In atrial fibrillation (AF)-related acute ischemic stroke, the optimal oral anticoagulation strategy remains unclear. OBJECTIVE To test whether rivaroxaban or warfarin sodium is safer and more effective for preventing early recurrent stroke in patients with AF-related acute ischemic stroke. DESIGN, SETTING, AND PARTICIPANTS A randomized, multicenter, open-label, blinded end point evaluation, comparative phase 2 trial was conducted from April 28, 2014, to December 7, 2015, at 14 academic medical centers in South Korea among patients with mild AF-related stroke within the previous 5 days who were deemed suitable for early anticoagulation. Analysis was performed on a modified intent-to-treat basis. INTERVENTIONS Participants were randomized 1:1 to receive rivaroxaban, 10 mg/d for 5 days followed by 15 or 20 mg/d, or warfarin with a target international normalized ratio of 2.0-3.0, for 4 weeks. MAIN OUTCOMES AND MEASURES The primary end point was the composite of new ischemic lesion or new intracranial hemorrhage seen on results of magnetic resonance imaging at 4 weeks. Primary analysis was performed in patients who received at least 1 dose of study medications and completed follow-up magnetic resonance imaging. Key secondary end points were individual components of the primary end point and hospitalization length. RESULTS Of 195 patients randomized, 183 individuals (76 women and 107 men; mean [SD] age, 70.4 [10.4] years) completed magnetic resonance imaging follow-up and were included in the primary end point analysis. The rivaroxaban group (n = 95) and warfarin group (n = 88) showed no differences in the primary end point (47 [49.5%] vs 48 [54.5%]; relative risk, 0.91; 95% CI, 0.69-1.20; P = .49) or its individual components (new ischemic lesion: 28 [29.5%] vs 31 of 87 [35.6%]; relative risk, 0.83; 95% CI, 0.54-1.26; P = .38; new intracranial hemorrhage: 30 [31.6%] vs 25 of 87 [28.7%]; relative risk, 1.10; 95% CI, 0.70-1.71; P = .68). Each group had 1 clinical ischemic stroke, and all new intracranial hemorrhages were asymptomatic hemorrhagic transformations. Hospitalization length was reduced with rivaroxaban compared with warfarin (median, 4.0 days [interquartile range, 2.0-6.0 days] vs 6.0 days [interquartile range, 4.0-8.0]; P < .001). CONCLUSIONS AND RELEVANCE In mild AF-related acute ischemic stroke, rivaroxaban and warfarin had comparable safety and efficacy. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT02042534.
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An S-warfarin and AZD1981 interaction: in vitro and clinical pilot data suggest the N-deacetylated amino acid metabolite as the primary perpetrator.
Grime, K, Pehrson, R, Nordell, P, Gillen, M, Kühn, W, Mant, T, Brännström, M, Svanberg, P, Jones, B, Brealey, C
British journal of clinical pharmacology. 2017;(2):381-392
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AIM: AZD1981 is an orally bioavailable chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTh2) receptor antagonist progressed to phase II trials for the treatment of allergic asthma. Previously performed in vitro human hepatocyte incubations identified N-deacetylated AZD1981 as a primary metabolite. We report on metabolite exposure from a clinical excretion balance, on in vitro studies performed to determine the likelihood of a metabolite-dependent drug-drug interaction (DDI) and on a clinical warfarin DDI study. The aim was to demonstrate that N-deacetylated AZD1981 is responsible for the observed interaction. METHODS The excretion and biotransformation of [14 C]-AZD1981 were studied in healthy male volunteers, and subsequently in vitro cytochrome P450 (CYP) inhibition and hepatocyte uptake investigations were carried out with metabolites and the parent drug. A clinical DDI study using coadministered twice-daily 100 mg and 400 mg AZD1981 with 25 mg warfarin was performed. RESULTS The excretion balance study showed N-deacetylated AZD1981 to be the most abundant metabolite present in plasma. In vitro data revealed the metabolite to be a weak CYP2C9 time-dependent inhibitor, subject to more active hepatic uptake than the parent molecule. Clinically, the S-warfarin area under the plasma concentration-time curve increased, on average, 1.4-fold [95% confidence interval (CI) 1.22, 1.50] and 2.4-fold (95% CI 2.11, 2.64) after 100 mg (n = 13) and 400 mg (n = 11) AZD1981 administration, respectively. In vitro CYP inhibition and hepatocyte uptake data were used to explain the interaction. CONCLUSIONS N-deacetylated AZD1981 can be added to the small list of drug metabolites reported as sole contributors to clinical drug-drug interactions, with weak time-dependent inhibition exacerbated by efficient hepatic uptake being the cause.
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Factors associated with non-vitamin K antagonist oral anticoagulants for stroke prevention in patients with new-onset atrial fibrillation: Results from the Outcomes Registry for Better Informed Treatment of Atrial Fibrillation II (ORBIT-AF II).
Steinberg, BA, Shrader, P, Thomas, L, Ansell, J, Fonarow, GC, Gersh, BJ, Hylek, E, Kowey, PR, Mahaffey, KW, O'Brien, EC, et al
American heart journal. 2017;:40-47
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BACKGROUND Several non-vitamin K antagonist oral anticoagulant (NOAC) alternatives to warfarin are available for stroke prevention in atrial fibrillation (AF). We aimed to describe the factors associated with selection of NOACs versus warfarin in patients with new onset AF. METHODS The ORBIT-AF II study is a national, US, prospective, observational, cohort study of anticoagulation treatment in patients with AF receiving NOACs or warfarin in the United States from 2013 to 2016. We measured factors associated with oral anticoagulant selection in 4,670 patients recently diagnosed with AF. RESULTS At baseline, 1,169 (25%) patients were started on warfarin and 3,501 (75%) on NOACs: of these latter, 259 (6%) were started on dabigatran, 1858 (40%) on rivaroxaban, and 1384 (30%) on apixaban. Those receiving NOACs were slightly younger patients (median age 71 vs 72, P<.0001); were less likely to have prior stroke (5.3% vs 8.6%; P<.0001) or prior bleeding (2.7% vs 4.4%; P=.005); had better kidney function (mean estimated glomerular filtration rate 91 mL/min vs 80 mL/min, P<.0001); and had fewer patients at high stroke risk (CHA2DS2-VASc score [Congestive heart failure, Hypertension, Age ≥75years, Diabetes mellitus, Prior stroke, transient ischemic attack {TIA}, or thromboembolism,Vascular disease, Age 65-74years, Sex category {female}] ≥2 in 86% vs 93%; P<.0001). In multivariable analysis, factors associated with NOAC selection versus warfarin included renal function, prior stroke or valve replacement, rhythm control AF management strategy, treatment by a cardiologist, and higher patient education level. CONCLUSIONS In contemporary clinical practice, up to three-fourths of patients with new-onset AF are now initially treated with a NOAC for stroke prevention. Those selected for NOAC treatment had lower stroke and bleeding risk profiles, were more likely treated by cardiologists, and had higher socioeconomic status. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01701817.
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Anticoagulation Control in Warfarin-Treated Patients Undergoing Cardioversion of Atrial Fibrillation (from the Edoxaban Versus Enoxaparin-Warfarin in Patients Undergoing Cardioversion of Atrial Fibrillation Trial).
Lip, GYH, Al-Saady, N, Jin, J, Sun, M, Melino, M, Winters, SM, Zamoryakhin, D, Goette, A
The American journal of cardiology. 2017;(5):792-796
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In the Edoxaban Versus Enoxaparin-Warfarin in Patients Undergoing Cardioversion of Atrial Fibrillation (ENSURE-AF) study (NCT 02072434), edoxaban was compared with enoxaparin-warfarin in 2,199 patients undergoing electrical cardioversion of nonvalvular atrial fibrillation (AF). In this multicenter prospective randomized open blinded end-point trial, we analyzed patients randomized to enoxaparin-warfarin. We determined time to achieve therapeutic range (TtTR); time in therapeutic range (TiTR); their clinical determinants; relation to sex, age, medical history, treatment, tobacco use, race risk (SAMe-TT2R2) score; and impact on primary end points (composite of stroke, systemic embolic event[SEE], myocardial infarction [MI], and cardiovascular death [CVD] and composite of major + clinically relevant nonmajor bleeding). Among 1,104 patients randomized to enoxaparin-warfarin, 27% were naïve to oral anticoagulants. Mean age was 64.2 ± 11 years and mean congestive heart failure, hypertension, age ≥75 (doubled), diabetes mellitus, prior stroke or transient ischemic attack (doubled), vascular disease, age 65-74, female (CHA2DS2-VASc) score was 2.6. Mean TtTR was 7.7 days (median 7 days) and mean TiTR after reaching an international normalized ratio of 2.0 to 3.0 was 71%. In 695 patients who had an INR <2.0 before the first dose and who reached an INR ≥2.0, 436 had a SAMe-TT2R2 score ≤2 and 259 had a score >2. On multivariate regression, an independent predictor of extended TtTR was creatinine clearance (p = 0.02). TtTR was marginally related to stroke/SEE/MI/CVD (p = 0.06; odds ratio 0.23, 95% confidence interval 0.02 to 1.17) but not to any bleeding. Independent predictors of TiTR were previous vitamin K antagonist experience (p<0.01) and low hypertension, abnormal renal or liver function, stroke, bleeding, labile INRs, age >65, concomitant drugs or alcohol (HAS-BLED) score (p = 0.02). TiTR was related to any bleeding (p = 0.02; odds ratio 0.39, 95% confidence interval 0.16 to 0.88), but not stroke/SEE/MI/CVD. In this cohort of warfarin users with a high TiTR no difference was seen between TtTR and TiTR in relation to SAMe-TT2R2 score. In conclusion, even in this short-term study, TiTR was significantly related to bleeding events.
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Edoxaban for the management of elderly Japanese patients with atrial fibrillation ineligible for standard oral anticoagulant therapies: Rationale and design of the ELDERCARE-AF study.
Okumura, K, Lip, GYH, Akao, M, Tanizawa, K, Fukuzawa, M, Abe, K, Akishita, M, Yamashita, T
American heart journal. 2017;:99-106
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Edoxaban-a non-vitamin K antagonist oral anticoagulant (NOAC)- 60-mg and 30-mg once-daily dose regimens are noninferior versus well-managed warfarin for the prevention of stroke or systemic embolic events (SEE) with less major bleeding in patients with nonvalvular atrial fibrillation (NVAF). There are no published data from phase 3 clinical trials specifically evaluating the use of NOACs in elderly NVAF patients, especially those considered ineligible for available oral anticoagulants. The Edoxaban Low-Dose for EldeR CARE AF patients (ELDERCARE-AF) study is a phase 3, randomized, double-blind, placebo-controlled, parallel-group, multicenter study that will compare the safety and efficacy of once-daily edoxaban 15 mg versus placebo in Japanese patients with NVAF ≥80 years of age who are considered ineligible for standard oral anticoagulant therapy. A total of 800 patients (400 in each treatment group) are planned for randomization (1:1) to either edoxaban or placebo using a stratified randomization method with CHADS2 index score (2 points, ≥3 points) as a factor. The primary efficacy end point is the time to first onset of stroke or SEE. The net clinical outcome is the composite of stroke, SEE, major bleeding, and all-cause mortality. The primary safety end point is the incidence of major bleeding. The treatment period will continue until 65 patients with the primary efficacy events (ie, stroke or SEE) have been observed (2- to 2.5-year expected mean treatment period). The results of ELDERCARE-AF may provide clarity as to the efficacy and safety of edoxaban for the prevention of stroke or SEE in this high-risk population.
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Effects of Fostamatinib on the Pharmacokinetics of Oral Contraceptive, Warfarin, and the Statins Rosuvastatin and Simvastatin: Results From Phase I Clinical Studies.
Martin, P, Gillen, M, Ritter, J, Mathews, D, Brealey, C, Surry, D, Oliver, S, Holmes, V, Severin, P, Elsby, R
Drugs in R&D. 2016;(1):93-107
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BACKGROUND AND OBJECTIVES Fostamatinib is a spleen tyrosine kinase inhibitor that has been investigated as therapy for rheumatoid arthritis and immune thrombocytopenic purpura. The present studies assessed the potential for pharmacokinetic interaction between fostamatinib and the commonly prescribed medications oral contraceptive (OC), warfarin, and statins (rosuvastatin, simvastatin) in healthy subjects. METHODS The OC study was a crossover study over two 28-day treatment periods (Microgynon(®) 30 plus placebo or fostamatinib). Concentrations of OC constituents (ethinyl estradiol/levonorgestrel) were measured. Effects on warfarin pharmacokinetics and pharmacodynamics were assessed (21-day study). Warfarin was administered on days 1 and 14, fostamatinib on days 8-20. The statin study was a two-period, fixed-sequence study of the effects of fostamatinib on exposure to rosuvastatin or simvastatin (single doses). Safety was assessed throughout. RESULTS Fostamatinib co-administration with OC increased exposure to ethinyl estradiol [area under the plasma concentration-time curve at steady state (AUCss) 28% [confidence interval (CI 90%) 21-36]; maximum plasma concentration (Cmax) at steady state (Cmax,ss) 34% (CI 26-43)], but not levonorgestrel (AUCss 5%; Cmax,ss -3%), while exposure to luteinizing hormone and follicle-stimulating hormone decreased (≈ 20%). Fostamatinib did not affect the pharmacokinetics/pharmacodynamics of warfarin to a clinically relevant extent, but caused an upward trend in AUC for both R- and S-warfarin [18% (CI 13-23) and 13% (CI 7-19)]. Fostamatinib increased rosuvastatin AUC by 96% (CI 78-115) and Cmax by 88% (CI 69-110), and increased simvastatin acid AUC by 74% (CI 50-102) and Cmax by 83% (CI 57-113). CONCLUSION Fostamatinib exhibits drug-drug interactions when co-administered with OC, simvastatin, or rosuvastatin, with the AUC of statins almost doubling. Fostamatinib did not exhibit a clinically relevant DDI on warfarin.
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Rivaroxaban in antiphospholipid syndrome (RAPS) protocol: a prospective, randomized controlled phase II/III clinical trial of rivaroxaban versus warfarin in patients with thrombotic antiphospholipid syndrome, with or without SLE.
Cohen, H, Doré, CJ, Clawson, S, Hunt, BJ, Isenberg, D, Khamashta, M, Muirhead, N, ,
Lupus. 2015;(10):1087-94
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INTRODUCTION The current mainstay of the treatment of thrombotic antiphospholipid syndrome (APS) is long-term anticoagulation with vitamin K antagonists (VKAs) such as warfarin. Non-VKA oral anticoagulants (NOACs), which include rivaroxaban, have been shown to be effective and safe compared with warfarin for the treatment of venous thromboembolism (VTE) in major phase III prospective, randomized controlled trials (RCTs), but the results may not be directly generalizable to patients with APS. AIMS The primary aim is to demonstrate, in patients with APS and previous VTE, with or without systemic lupus erythematosus (SLE), that the intensity of anticoagulation achieved with rivaroxaban is not inferior to that of warfarin. Secondary aims are to compare rates of recurrent thrombosis, bleeding and the quality of life in patients on rivaroxaban with those on warfarin. METHODS Rivaroxaban in antiphospholipid syndrome (RAPS) is a phase II/III prospective non-inferiority RCT in which eligible patients with APS, with or without SLE, who are on warfarin, target international normalized ratio (INR) 2.5 for previous VTE, will be randomized either to continue warfarin (standard of care) or to switch to rivaroxaban. Intensity of anticoagulation will be assessed using thrombin generation (TG) testing, with the primary outcome the percentage change in endogenous thrombin potential (ETP) from randomization to day 42. Other TG parameters, markers of in vivo coagulation activation, prothrombin fragment 1.2, thrombin antithrombin complex and D-dimer, will also be assessed. DISCUSSION If RAPS demonstrates i) that the anticoagulant effect of rivaroxaban is not inferior to that of warfarin and ii) the absence of any adverse effects that cause concern with regard to the use of rivaroxaban, this would provide sufficient supporting evidence to make rivaroxaban a standard of care for the treatment of APS patients with previous VTE, requiring a target INR of 2.5.
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The Creating an Optimal Warfarin Nomogram (CROWN) Study.
Perlstein, TS, Goldhaber, SZ, Nelson, K, Joshi, V, Morgan, TV, Lesko, LJ, Lee, JY, Gobburu, J, Schoenfeld, D, Kucherlapati, R, et al
Thrombosis and haemostasis. 2012;(1):59-68
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A significant proportion of warfarin dose variability is explained by variation in the genotypes of the cytochrome P450 CYP2C9 and the vitamin K epoxide reductase complex, VKORC1, enzymes that influence warfarin metabolism and sensitivity, respectively. We sought to develop an optimal pharmacogenetic warfarin dosing algorithm that incorporated clinical and genetic information. We enroled patients initiating warfarin therapy. Genotyping was performed of the VKORC1, -1639G>A, the CYP2C9*2, 430C>T, and the CYP2C9*3, 1075C>A genotypes. The initial warfarin dosing algorithm (Algorithm A) was based upon established clinical practice and published warfarin pharmacogenetic information. Subsequent dosing algorithms (Algorithms B and Algorithm C) were derived from pharmacokinetic / pharmacodynamic (PK/PD) modelling of warfarin dose, international normalised ratio (INR), clinical and genetic factors from patients treated by the preceding algorithm(s). The primary outcome was the time in the therapeutic range, considered an INR of 1.8 to 3.2. A total of 344 subjects are included in the study analyses. The mean percentage time within the therapeutic range for each subject increased progressively from Algorithm A to Algorithm C from 58.9 (22.0), to 59.7 (23.0), to 65.8 (16.9) percent (p = 0.04). Improvement also occurred in most secondary endpoints, which included the per-patient percentage of INRs outside of the therapeutic range (p = 0.004), the time to the first therapeutic INR (p = 0.07), and the time to achieve stable therapeutic anticoagulation (p < 0.001). In conclusion, warfarin pharmacogenetic dosing can be optimised in real time utilising observed PK/PD information in an adaptive fashion.
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Absence of novel CYP4F2 and VKORC1 coding region DNA variants in patients requiring high warfarin doses.
Burmester, JK, Berg, RL, Glurich, I, Yale, SH, Schmelzer, JR, Caldwell, MD
Clinical medicine & research. 2011;(3-4):119-24
Abstract
OBJECTIVE Warfarin is an FDA-approved oral anticoagulant for long-term prevention of thromboembolism. Substantial inter-individual variation in dosing requirements and the narrow therapeutic index of this widely-prescribed drug make safe initiation and dose stabilization challenging. Single nucleotide polymorphisms (SNPs) occurring in CYP2C9, VKORC1, and CYP4F2 genes are known to impact dose, and VKORC1 and CYP4F2 polymorphisms are associated with higher therapeutic dose requirements in our cohort. However, the most advanced regression models using personal, clinical, and genetic factors to predict individual stable dose account for only 50% to 60% of the observed variability in stable therapeutic dose in Caucasians. DESIGN AND METHODS In this study, we used DNA sequence analysis to determine whether additional variants in CYP4F2 and VKORC1 gene coding regions contribute to variable dosing requirements among individuals for whom the actual dose was the highest relative to regression model- predicted dose. RESULTS AND CONCLUSIONS No novel DNA variants in the coding regions of these genes were identified among subjects requiring high warfarin doses, suggesting that other factors yet to be defined contribute to variability in warfarin dose requirements in this subset of our cohort.