| 1. |
- McClune, Brian L., et al.
(författare)
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Allotransplantation for Patients Age >= 40 Years with Non-Hodgkin Lymphoma : Encouraging Progression-Free Survival
- 2014
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Ingår i: Biology of blood and marrow transplantation. - : Elsevier BV. - 1083-8791 .- 1523-6536. ; 20:7, s. 960-968
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Tidskriftsartikel (refereegranskat)abstract
- Non-Hodgkin lymphoma (NHL) disproportionately affects older patients, who do not often undergo allogeneic hematopoietic cell transplantation (HCT). We analyzed Center for International Blood and Marrow Transplant Research data on 1248 patients age >= 40 years receiving reduced-intensity conditioning (RIC) or nonmyeloablative (NMA) conditioning HCT for aggressive (n = 668) or indolent (n = 580) NHL Aggressive lymphoma was more frequent in the oldest cohort 49% for age 40 to 54 versus 57% for age 55 to 64 versus 67% for age >= 65; P = .0008). Fewer patients aged >= 65 had previous autografting (26% versus 24% versus 9%; P = .002). Rates of relapse, acute and chronic GVHD, and nonrelapse mortality (NRM) at 1 year post-HCT were similar in the 3 age cohorts (22% [95% confidence interval (CI), 19% to 26%] for age 40 to 54, 27% [95% CI, 23% to 31%] for age 55 to 64, and 34% [95% CI, 24% to 44%] for age >= 65. Progression-free survival (PFS) and overall survival (OS) at 3 years was slightly lower in the older cohorts (OS: 54% [95% CI, 50% to 58%] for age 40 to 54; 40% [95% CI, 36% to 44%] for age 55 to 64, and 39% [95% CI, 28% to 50%] for age >= 65; P < .0001). Multivariate analysis revealed no significant effect of age on the incidence of acute or chronic GVHD or relapse. Age >= 55 years, Karnofsky Performance Status <80, and HLA mismatch adversely affected NRM, PFS, and OS. Disease status at HCT, but not histological subtype, was associated with worse NRM, relapse, PFS, and OS. Even for patients age >= 55 years, OS still approached 40% at 3 years, suggesting that HCT affects long-term remission and remains underused in qualified older patients with NHL.
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| 2. |
- Erlinge, David, et al.
(författare)
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Clopidogrel metaboliser status based on point-of-care CYP2C19 genetic testing in patients with coronary artery disease
- 2014
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Ingår i: Thrombosis and Haemostasis. - 0340-6245 .- 2567-689X. ; 111:5, s. 943-950
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Tidskriftsartikel (refereegranskat)abstract
- We compared results obtained with the Nanosphere Verigene (R) System, a novel point-of-care (POC) genetic test capable of analysing 11, CYP2C19 variants within 3 hours, to an established, validated genotyping method (Affymetrix (TM) DMET+; reference assay) for identifying extensive and reduced metabolisers of clopidogrel. Based on genotyping, patients (N=82) with stable coronary artery disease on clopidogrel 75 mg daily were defined as extensive metabolisers (*1/*1, *1/*17,*17/*17), reduced metabolisers (*1/*2,*1/*8,*2/*2,*2/*3), or of indeterminate metaboliser status (*2/*17). Pharmacokinetic exposure to clopidogrel's active metabolite and pharmacodynamic measures with P2Y12 reaction units (PRU) (VerifyNow (R) P2Y12 assay), and VASP PRI (PRI) were also assessed. There was a 99.9% overall; concordance of marker-level data between the Nanosphere Verigene and DMET+ systems in identifying the CYP2C19 variants and 100% agreement in classifying the patients as extensive (n=59) or reduced metabolisers (n=15). Extensive metabolisers had significantly higher active metabolite exposure than reduced metabolisers (LS means 12.6 ng*h/ml vs 7.7 ng*h/ml; p<0.001). Extensive metabolisers also had lower PRU (LS means 158 vs 212; p=0.003) and VASP PRI (LS means 48% vs 63%, p=0.01) compared to reduced metabolisers. Rates of high on-treatment platelet reactivity were higher in reduced metabolisers compared to extensive metabolisers (VASP PRI >= 50%: 79% vs 47%; PRU >235: 33% vs 16%). The Nanosphere Verigene CBS system identified 11 CYP2C19 alleles in less than 3 hours with a high degree of accuracy when compared to a conventional method, and was further validated against pharmacokinetic and pharmacodynamic phenotypes.
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| 3. |
- Gurbel, Paul A., et al.
(författare)
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Platelet Function During Extended Prasugrel and Clopidogrel Therapy for Patients With ACS Treated Without Revascularization The TRILOGY ACS Platelet Function Substudy
- 2012
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Ingår i: JAMA: The Journal of the American Medical Association. - : American Medical Association (AMA). - 1538-3598. ; 308:17, s. 1785-1794
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Tidskriftsartikel (refereegranskat)abstract
- Context The relationship of platelet function testing measurements with outcomes in patients with acute coronary syndromes (ACS) initially managed medically without revascularization is unknown. Objective To characterize the differences and evaluate clinical outcomes associated with platelet reactivity among patients with ACS treated with clopidogrel or prasugrel. Design, Setting, and Patients Patients with medically managed unstable angina or non-ST-segment elevation myocardial infarction were enrolled in the TRILOGY ACS trial (2008 to 2011) comparing clopidogrel vs prasugrel. Of 9326 participants, 27.5% were included in a platelet function substudy: 1286 treated with prasugrel and 1278 treated with clopidogrel. Interventions Aspirin with either prasugrel (10 or 5 mg/d) or clopidogrel (75 mg/d); those 75 years or older and younger than 75 years but who weighed less than 60 kg received a 5-mg prasugrel maintenance dose. Main Outcome Measures Platelet reactivity, measured in P2Y(12) reaction units (PRUs), was performed at baseline, at 2 hours, and at 1, 3, 6, 12, 18, 24, and 30 months after randomization. The primary efficacy end point was a composite of cardiovascular death, myocardial infarction, or stroke through 30 months. Results Among participants younger than 75 years and weighing 60 kg or more, the median PRU values at 30 days were 64 (interquartile range [IQR], 33-128) in the prasugrel group vs 200 (IQR, 141-260) in the clopidogrel group (P<.001), a difference that persisted through all subsequent time points. For participants younger than 75 years and weighing less than 60 kg, the median 30-day PRU values were 139 (IQR, 86-203) for the prasugrel group vs 209 (IQR, 148-283) for the clopidogrel group (P<.001), and for participants 75 years or older, the median PRU values were 164 (IQR, 105-216) for the prasugrel group vs 222 (IQR, 148-268) for the clopidogrel group (P<.001). At 30 months the rate of the primary efficacy end point was 17.2% (160 events) in the prasugrel group vs 18.9% (180 events) in the clopidogrel group (P=.29). There were no significant differences in the continuous distributions of 30-day PRU values for participants with a primary efficacy end point event after 30 days (n=214) compared with participants without an event (n=1794; P=.07) and no significant relationship between the occurence of the primary efficacy end point and continuous PRU values (adjusted hazard ratio [HR] for increase of 60 PRUs, 1.03; 95% CI, 0.96-1.11; P=.44). Similar findings were observed with 30-day PRU cut points used to define high on-treatment platelet reactivity-PRU more than 208 (adjusted HR, 1.16; 95% CI, 0.89-1.52, P=.28) and PRU more than 230 (adjusted HR, 1.20; 95% CI, 0.90-1.61; P=.21). Conclusions Among patients with ACS without ST-segment elevation and initially managed without revascularization, prasugrel was associated with lower platelet reactivity than clopidogrel, irrespective of age, weight, and dose. Among those in the platelet substudy, no significant differences existed between prasugrel vs clopidogrel in the occurence of the primary efficacy end point through 30 months and no significant association existed between platelet reactivity and occurrence of ischemic outcomes.
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| 4. |
- Gurbel, Paul A., et al.
(författare)
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The effect of CYP2C19 gene polymorphisms on the pharmacokinetics and pharmacodynamics of prasugrel 5-mg, prasugrel 10-mg and clopidogrel 75-mg in patients with coronary artery disease
- 2014
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Ingår i: Thrombosis and Haemostasis. - : Schattauer. - 0340-6245 .- 2567-689X. ; 112:3, s. 589-597
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Tidskriftsartikel (refereegranskat)abstract
- CYP2C19 genotype has been shown to impact response to clopidogrel 75-mg but not prasugrel 10-mg. Here, we assessed effects of CYP2C19 metaboliser status on pharmacokinetics (PK) and pharmacodynamic (PD) responses to prasugrel 5-mg and 10-mg and clopidogrel 75-mg using data from two PK/PD studies in stable coronary artery disease (CAD) patients (GENERATIONS and FEATHER). Active metabolite concentrations (area under the curve, AUC([0-tlast])), maximum platelet aggregation (MPA) measured by light transmission aggregometry, vasodilator-stimulated phosphoprotein platelet reactivity index, and VerifyNow P2Y12-platelet reaction units (VN-PRU) were analysed by CYP2C19-predicted phenotype (extensive metaboliser [EM; N=154], *2-*8 non-carriers, vs reduced metaboliser [RM; N=41],*2-*8 carriers/*17 non-carriers). AUC((0-tlast)) was unaffected by metaboliser status for prasugrel 5-mg and 10-mg (geometric mean EM/RM ratios 1.00, 95% confidence interval [Cl]: 0.86,1.17, p>0.99; and 0.97, 95% CI:0.85,1.12, p=0.71, respectively), but was lower among RMs receiving clopidogrel 75-mg (1.37, 95% CI:1.14,1.65, p<0.001). Platelet reactivity was not significantly affected by CYP2C19 metaboliser status for prasugrel 5-mg, or for prasugrel 10-mg by MPA and VN-PRU, but for clopidogrel 75-mg was significantly higher in reduced metabolisers (all measures p<0.01). Prasugrel 10-mg showed greater antiplatelet effects vs clopidogrel 75-mg (all comparisons p<0.001). Prasugrel 5-mg showed greater antiplatelet effects vs clopidogrel 75-mg in RMs (all p<0.001), and comparable effects in EMs (all p >= 0.37). In contrast to clopidogrel, prasugrel active metabolite PK was not influenced by CYP2C19 genotype. Antiplatelet effect for prasugrel 10-mg was greater irrespective of metaboliser status and for prasugrel 5-mg was greater for RMs and comparable for EMs as compared to clopidogrel 75-mg.
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| 5. |
- Erlinge, David, et al.
(författare)
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Prasugrel 5-mg in the very elderly attenuates platelet inhibition but maintains non-inferiority to prasugrel 10-mg in non-elderly patients: The GENERATIONS trial, a pharmacodynamic and pharmacokinetic study in stable coronary artery disease patients.
- 2013
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Ingår i: Journal of the American College of Cardiology. - : Elsevier BV. - 0735-1097. ; 62:7, s. 577-583
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: We assessed pharmacodynamic (PD) response for the reduced prasugrel 5-mg maintenance dose in very elderly (≥75y; VE) patients. BACKGROUND: In TRITON-TIMI 38, prasugrel 10-mg reduced ischemic events versus clopidogrel 75-mg, but increased bleeding in VE patients. METHODS: We examined PD and active-metabolite pharmacokinetics with prasugrel 5-mg and 10-mg and clopidogrel 75-mg in a three-period (12 days each), blinded, cross-over study in VE (n=73, mean 79±3y) or non-elderly (≥45-<65y, NE) (n=82, 56±5y) stable coronary artery disease (CAD) patients on background aspirin. Assays included light transmission aggregometry (LTA), VerifyNow(®) P2Y12 (VN-P2Y12), and VASP. The primary comparison was non-inferiority of maximum platelet aggregation (MPA) comparing the median for prasugrel 5-mg in VE versus the 75th percentile for prasugrel 10-mg in NE, using a prespecified one-sided 97.5% confidence interval for the difference <15%. RESULTS: Prasugrel 5-mg in VE met the primary pharmacodynamic non-inferiority criterion versus prasugrel 10-mg in NE. For prasugrel 5-mg, MPA was significantly lower (mean±SD, 57±14%) than clopidogrel (63±14%) (p<0.001) in VE, but higher than prasugrel 10-mg in NE (46±12%) (p<0.001). PD response by LTA, VN-P2Y12, and VASP during all treatments appeared similar between age cohorts. Prasugrel 5-mg resulted in fewer VE poor responders versus clopidogrel. Rates of mild bleeding were higher with prasugrel 10-mg, but similar for prasugrel 5-mg versus clopidogrel 75-mg. CONCLUSIONS: In aspirin-treated stable CAD patients, prasugrel 5-mg in VE attenuated platelet inhibition while meeting prespecified non-inferiority criterion versus prasugrel 10-mg in NE, with significantly better PD response and fewer poor responders compared to clopidogrel 75-mg in VE.
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| 6. |
- Erlinge, David, et al.
(författare)
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Prasugrel 5 mg in the Very Elderly Attenuates Platelet Inhibition But Maintains Noninferiority to Prasugrel 10 mg in Nonelderly Patients
- 2013
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Ingår i: Journal of the American College of Cardiology. - : Elsevier. - 0735-1097 .- 1558-3597. ; 62:7, s. 577-583
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Tidskriftsartikel (refereegranskat)abstract
- Objectives This study assessed pharmacodynamic (PD) response to the reduced prasugrel maintenance dose of 5 mg in very elderly (VE) patients (andgt;= 75 years of age). less thanbrgreater than less thanbrgreater thanBackground In the TRITON-TIMI 38 (TRial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet InhibitioN with Prasugrel-Thrombolysis In Myocardial Infarction 38) study prasugrel 10 mg reduced ischemic events versus clopidogrel 75 mg, but increased bleeding in VE patients. less thanbrgreater than less thanbrgreater thanMethods We examined PD and active metabolite pharmacokinetics (PKs) with prasugrel 5 and 10 mg and clopidogrel 75 mg in a 3-period (12 days each) blinded, crossover study in VE (n = 73; mean: 79 +/- 3 years of age) or (n 82) nonelderly (NE) (andgt;= 45 to andlt;65 years of age; mean: 56 +/- 5 years of age) stable coronary artery disease (CAD) patients receiving background aspirin. Assays included light transmission aggregometry (LTA), VerifyNow P2Y12 (VN-P2Y12), and vasodilator-associated stimulated phosphoprotein (VASP). The primary comparison was noninferiority of maximum platelet aggregation (MPA) comparing the median for prasugrel 5 mg in VE versus the 75th percentile for prasugrel 10 mg in NE, using a pre-specified 1-sided 97.5% confidence interval for the difference andlt;15%. less thanbrgreater than less thanbrgreater thanResults Prasugrel 5 mg in VE met the primary PD noninferiority criterion versus prasugrel 10 mg in NE. For prasugrel 5 mg, MPA was significantly lower (57 +/- 14%) than clopidogrel (63 +/- 14%; p andlt; 0.001) in VE but higher than prasugrel 10 mg in NE (46 +/- 12%; p andlt; 0.001). PD response by LTA, VN-P2Y12, and VASP during all treatments appeared similar between age cohorts. Prasugrel 5 mg resulted in fewer VE poor responders than clopidogrel. Rates of mild bleeding were higher with prasugrel 10 mg but similar for prasugrel 5 mg versus clopidogrel 75 mg. less thanbrgreater than less thanbrgreater thanConclusions In aspirin-treated stable CAD patients, prasugrel 5 mg in VE attenuated platelet inhibition while meeting pre-specified noninferiority criterion versus prasugrel 10 mg in NE, with significantly better PD response and fewer poor responders compared to clopidogrel 75 mg in VE. (Comparison of Prasugrel and Clopidogrel in Very Elderly and Non-Elderly Patients With Stable Coronary Artery Disease [GENERATIONS]; NCT01107912)
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| 7. |
- Braun, Oscar, et al.
(författare)
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Enhanced active metabolite generation and platelet inhibition with prasugrel compared to clopidogrel regardless of genotype in thienopyridine metabolic pathways
- 2013
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Ingår i: Thrombosis and Haemostasis. - 0340-6245 .- 2567-689X. ; 110:6, s. 1223-1231
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Tidskriftsartikel (refereegranskat)abstract
- Clopidogrel response varies according to the presence of genetic polymorphisms. The CYP2C19*2 allele has been associated with impaired response; conflicting results have been reported for CYP2C19*17, ABCB1, and PON1 genotypes. We assessed the impact of CYP2C19, PON1, and ABCB1 polymorphisms on clopidogrel and prasugrel pharmacodynamic (PD) and pharmacokinetic (PK) parameters. Aspirin-treated patients (N=194) with coronary artery disease from two independent, prospective, randomised, multi-centre studies comparing clopidogrel (75 mg) and prasugrel (10 mg) were genotyped and classified by predicted CYP2C19 metaboliser phenotype (ultra metabolisers [UM] = *17 carriers; extensive metabolisers [EM] = *1/1 homozygotes; reduced metabolisers [RM] = *2 carriers). ABCB1 T/T and C/T polymorphisms and PON1 A/A, A/G and G/G polymorphisms were also genotyped. PD parameters were assessed using VerifyNow (R) P2Y12 and vasodilator stimulated phosphoprotein (VASP) expressed as platelet reactivity index (PR!) after 14 days of maintenance dosing. Clopi-, dogrel and prasugrel active metabolite (AM) exposure was calculated in a cohort of 96 patients. For clopidogrel, genetic variants in CYP2C19, but notABCB1 or PON1, affected PK and PD. For prasugrel, none of the measured genetic variants affected PK or PD. Compared with clopidogrel, platelet inhibition with prasugrel was greater even in the CYP2C19 UM phenotype. Prasugrel generated more AM and achieved greater platelet inhibition than clopidogrel irrespective of CYP2C19, ABCB1, and PON1 polymorphisms. The lack of effect from genetic variants on prasugrel AM generation or antiplatelet activity is consistent with previous studies in healthy volunteers and is consistent with improved efficacy in acute coronary syndrome patients managed with percutaneous coronary intervention.
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| 8. |
- Gurbel, Paul A., et al.
(författare)
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Translational platelet research in patients with coronary artery disease: hat are the rnalor knowledge gaps?
- 2012
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Ingår i: Thrombosis and Haemostasis. - 0340-6245. ; 108:1, s. 12-20
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Forskningsöversikt (refereegranskat)abstract
- Translational platelet function investigations performed in the percutaneous coronary intervention (PCI)-treated population receiving clopidogrel have identified high platelet reactivity to ADP (HPR) as a major risk factor for both acute as well as long-term ischaemic event occurrence, including stent thrombosis. Recent studies have highlighted the relation of single nucleotide polymorphisms of genes involved in clopidogrel absorption and metabolism to reduced pharmacokinetic and pharmacodynamic responses to clopidogrel. CYP2C19 loss-of-function (LoF) allele carriage has been associated with increased thrombotic risk in the PCI population. However, there is no information regarding the utility of platelet function testing to predict outcomes in patients with stable coronary artery disease and in medically managed patients with acute coronary syndromes. Additionally, few studies have included longitudinal assessment of platelet function to assess a potential time-dependent relation to ischaemic event occurrence and no phase-III antiplatelet-therapy trial has included a large enough platelet function sub-study to examine the relation between on-treatment platelet reactivity, bleeding, and ischaemic event occurrence. Therefore, futher studies are needed to delineate the role of platelet function testing across the spectrum of symptomatic coronary artery disease.
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| 9. |
- Jakubowski, Joseph A., et al.
(författare)
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The influence of body size on the pharmacodynamic and pharmacokinetic response to clopidogrel and prasugrel : A retrospective analysis of the FEATHER study
- 2014
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Ingår i: Thrombosis Research. - : Elsevier BV. - 0049-3848 .- 1879-2472. ; 134:3, s. 552-557
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Patients treated with clopidogrel who have higher body size exhibit greater platelet reactivity than patients with lower body size. In a retrospective analysis of the FEATHER trial, we examined the relationship between platelet response to thienopyridines clopidogrel 75 mg (Clop-75), prasugrel 5 mg (Pras-5), and prasugrel 10 mg (Pras-10) using 3 body size indices: body weight (BW), body mass index (BMI), and body surface area (BSA). Relationships were assessed as continuous variables and as 4 incremental body size groups. Materials and Methods: Aspirin-treated patients with stable coronary artery disease (N = 72) and a BW range of 45-134 kg received Clop-75, Pras-5, and Pras-10 in a 3-period, blinded, cross-over study. Platelet assays included maximum platelet aggregation (MPA) to 20 mu M ADP by light transmission aggregometry, VerifyNow-P2Y12 reaction units (PRU), and vasodilator-associated stimulated phosphoprotein (VASP) phosphorylation platelet reactivity index (PRI). Exposure to active metabolites (AMs) was also assessed. Results: Body size was a determinant of AM exposure and residual platelet reactivity regardless of type and dose of thienopyridine. BW and BSA demonstrated marginally stronger correlations with platelet reactivity; VASP-PRI demonstrated a stronger correlation with the body size than the other tests. Correlation coefficients ranged from a high of 0.64 (BW vs. PRI on Pras-5) to a low of 0.34 (BMI vs. MPA on Pras-10), but all were statistically significant (p < 0.01). Conclusions: Using a comprehensive selection of body size indices, AM exposures, platelet function tests, and thienopyridine doses, we demonstrated a consistent inverse relationship between body size and response to clopidogrel and prasugrel. (C) 2014 Elsevier Ltd. All rights reserved.
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| 10. |
- Wagner, Henrik, et al.
(författare)
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Higher body weight patients on clopidogrel maintenance therapy have lower active metabolite concentrations, lower levels of platelet inhibition, and higher rates of poor responders than low body weight patients
- 2014
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Ingår i: Journal of Thrombosis and Thrombolysis. - : Springer Science and Business Media LLC. - 0929-5305 .- 1573-742X. ; 38:2, s. 127-136
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Tidskriftsartikel (refereegranskat)abstract
- Body weight is a predictor of clopidogrel response. However, no prospective studies have compared pharmacodynamic (PD) and pharmacokinetic (PK) data based on body weight. We compared PD and PK effects of clopidogrel 75 mg in low body weight (LBW, <60 kg) and higher body weight (HBW, >= 60 kg) patients with stable coronary artery disease. LBW (n = 34, 56.4 +/- 3.7 kg) and HBW (n = 38, 84.7 +/- 14.9 kg) aspirin-treated patients received clopidogrel 75 mg for 10-14 days. The area under the concentration-time curve of active metabolite (Clop-AM) calculated through the last quantifiable concentration up to 4 h postdose, AUC((0-tlast)), was calculated by non-compartmental methods. Light transmission aggregometry (LTA) (maximum platelet aggregation and inhibition of platelet aggregation to 20 mu M adenosine diphosphate (ADP), and residual platelet aggregation to 5 mu M ADP), VerifyNow (R) P2Y12 reaction units (PRU), and vasodilator-associated stimulated phosphoprotein phosphorylation platelet reactivity index (VASP-PRI) were performed. Mean AUC((0-tlast)) was lower in HBW than LBW patients: 12.8 versus 17.9 ng h/mL. HBW patients had higher platelet reactivity as measured by LTA (all p <= 0.01), PRU (207 +/- 68 vs. 152 +/- 57, p < 0.001), and VASP-PRI (56 +/- 18 vs. 39 +/- 17, p < 0.001). More HBW patients exhibited high on-treatment platelet reactivity (HPR) using PRU (35 vs. 9 %) and VASP-PRI (65 vs. 27 %). Body weight correlated with PRU and VASP-PRI (both p < 0.001), and inversely with log transformed AUC((0-tlast)) (p < 0.001). In conclusion, HBW patients had lower levels of Clop-AM, and higher platelet reactivity and rates of HPR than LBW subjects, contributing to their suboptimal response to clopidogrel.
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| 11. |
- Jakubowski, Joseph A, et al.
(författare)
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TRITON and Beyond: New Insights into the Profile of Prasugrel.
- 2012
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Ingår i: Cardiovascular Therapeutics. - : Wiley. - 1755-5914. ; 30:4, s. 174-182
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Tidskriftsartikel (refereegranskat)abstract
- Prasugrel, a third-generation thienopyridine antiplatelet agent, demonstrated superior efficacy to clopidogrel but with an increased risk of bleeding in the phase III pivotal registration Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition with Prasugrel-Thrombolysis in Myocardial Infarction (TRITON-TIMI 38). This article reviews and discusses select components of a large literature of prasugrel data that has emerged since the TRITON-TIMI 38 (TRITON) study primary disclosure.
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| 12. |
- Judge, Heather M, et al.
(författare)
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Relationship between degree of P2Y12 receptor blockade and inhibition of P2Y12-mediated platelet function.
- 2010
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Ingår i: Thrombosis and Haemostasis. - 0340-6245 .- 2567-689X. ; 103:6
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Tidskriftsartikel (refereegranskat)abstract
- The thienopyridine P2Y12 receptor antagonists clopidogrel and prasugrel prevent arterial thrombosis and are routinely used following percutaneous coronary intervention. However, the optimal level of P2Y12 blockade to effectively inhibit platelet function is unknown. These studies utilised the active metabolite of prasugrel (R-138727) to achieve a range of P2Y12 blockade in vitro and assessed several aspects of platelet function. Blood from healthy volunteers was incubated with R-138727 (0-10 microM). P2Y12 receptor number was assessed using a 33P-2MeSADP binding assay. Platelet aggregation (PA) was measured by optical aggregometry with ADP 2-20 microM. VASP phosphorylation, annexin V binding, microparticle formation and P-selectin expression were assessed by flow cytometry. Increasing numbers of unblocked receptors were required for a sustained aggregation response with decreasing concentrations of ADP. A P2Y12 receptor blockade of 60-80% resulted in strong inhibition of final PA response, P-selectin expression, microparticle formation and vasodilator-stimulated phosphoprotein (VASP). PA induced by ADP 2 microM and P-selectin expression were particularly sensitive to low levels of receptor blockade whereas the VASP phosphorylation assay was relatively insensitive, requiring 60% receptor blockade to achieve substantial inhibition. Different assays varied in their ability to discriminate particular ranges of P2Y12 blockade and 80% or greater P2Y12 receptor blockade is required for consistently strong inhibition of several aspects of platelet function. These data guide the interpretation of results from different assays used to monitor the effects of P2Y12 receptor antagonists.
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