Modern antiplatelet agents in coronary artery disease

Dual antiplatelet therapy is well recognized in the prevention of thrombotic complications of acute coronary syndrome and percutaneous coronary interventions. Despite clinical benefits of aspirin and clopidogrel therapy, a number of limitations curtail their efficacy: slow onset of action, variability in platelet inhibitory response and potential drug–drug interactions. Furthermore, the single platelet-activation pathway targeted by these agents allows continued platelet activation via other pathways, ensuring incomplete protection against ischemic events, thus, underscoring the need for alternate antiplatelet treatment strategies. A number of novel antiplatelet agents are currently in advance development and many have established superior effects on platelet inhibition, clinical outcomes and safety profile than clopidogrel in high-risk patients. The aim of this review is to provide an overview of the current status of P2Y12 receptor inhibition and PAR-1 antagonists in determining a future strategy for individualized antiplatelet therapy.     

Antithrombotic Management of Elderly Patients With Coronary Artery Disease

Antithrombotic therapy represents the mainstay of treatment in patients with coronary artery disease (CAD), including elderly patients who are at increased risk for ischemic recurrences. However, the elderly population is also more vulnerable to bleeding complications. Numerous mechanisms, including abnormalities in the vasculature, thrombogenicity, comorbidities, and altered drug response, contribute to both increased thrombotic and bleeding risk. Age-related organ changes and drug-drug interactions secondary to polypharmacy lead to distinct pharmacokinetic and pharmacodynamic profiles of antithrombotic drugs. Overall these factors contribute to the risk-benefit profiles of antithrombotic therapies in elderly subjects and underscore the need for treatment regimens that can reduce bleeding while preserving efficacy. Given that the prevalence of CAD, as well as concomitant diseases with thromboembolic potential, such as atrial fibrillation, increases with age and that the elderly population is in continuous growth, understanding the safety and efficacy of different antithrombotic regimens is pivotal for patient-centered care. In the present overview the authors appraise the available data on the use of antithrombotic therapy in older patients with CAD to assist with the management of this high-risk population and define knowledge gaps that can set the basis for future research.     

Head‐to‐head comparison of prasugrel versus ticagrelor in patients undergoing percutaneous coronary intervention: A meta‐analysis of randomized controlled trials

Objectives

We sought to compare the efficacy and safety of prasugrel and ticagrelor in patients with coronary artery disease undergoing percutaneous coronary intervention (PCI).

Background

Evidence from randomized head‐to‐head comparison between prasugrel and ticagrelor is rare regarding clinical endpoints.

Methods

PubMed, the Cochrane Library, and Web of Science were queried with the terms “prasugrel,” “ticagrelor,” and “randomized.” Relevant randomized controlled trials (RCTs) or the same terms were also surveyed using clinicaltrials.gov , escardio.org , pcronline.org , and tctmd.com . The clinical endpoints were death, myocardial infarction (MI), stroke, and stent thrombosis (ST) for efficacy, and any bleeding for safety.

Results

A total number of 2068 patients in 12 RCTs, whose longest follow‐up period was 6 months, was included in this study. The risks of death (odds ratio [OR]: 0.86, 95% confidence interval [CI]: 0.46‐1.62, P = 0.647), MI (OR: 1.61, 95%CI: 0.71‐3.62, P = 0.252), stroke (OR: 1.45, 95%CI: 0.25‐8.36, P = 0.680), and ST (OR: 0.76, 95%CI: 0.20‐2.81, P = 0.677) were similar between prasugrel and ticagrelor, respectively. While the incidence of bleeding according to the Bleeding Academic Research Consortium definitions was also comparable (OR: 0.83, 95%CI: 0.45‐1.52, P = 0.539), that according to the Thrombolysis in Myocardial Infarction criteria was lower in prasugrel than ticagrelor (OR: 0.49, 95%CI: 0.24‐0.97, P = 0.042).

Conclusions

Although the efficacy was similar between prasugrel and ticagrelor, prasugrel may be associated with a lower risk of bleeding compared with ticagrelor during short‐ to mid‐term follow‐up period after PCI. Further studies are warranted in a larger patient population during longer‐term follow up to validate these findings.

     

Safety and efficacy of IIb/IIIa inhibitors in combination with highly active oral antiplatelet regimens in acute coronary syndromes: A meta-analysis of pivotal trials

The risk and benefit of GP-IIb/IIIa Inhibition (GPI) in combination with recent antiplatelet regimens in acute coronary syndromes (ACS) remain unassessed. The advent of fast-acting highly active oral P2Y₁₂ inhibitors questions the additional value and risk of their association with GPI. We studied the effect of GPI in combination with prasugrel and ticagrelor, compared to clopidogrel on major bleeding in pivotal randomized controlled trials in the setting of ACS, using a meta-analytic approach. A similar analysis, further including the comparison of a double versus standard dose clopidogrel regimen, was performed for the risk of the primary efficacy endpoint. The combination of GPI and recent P2Y₁₂ inhibitors was associated with a similar risk of bleeding as compared with GPI and the standard clopidogrel regimen (RR 0.92 [0.74; 1.13]). The benefit of recent regimens, including double dose clopidogrel, in reducing the primary ischemic endpoint (RR 0.86 [0.78; 0.94]) persisted in those treated with GPI. Although GPI use was associated with a consistent increase in the risk of bleeding in both recent (RR 1.27 [1.05–1.55]) and standard regimens (RR 2.01 [1.64–2.47]), the relative magnitude of such an increase was lower in association with prasugrel or ticagrelor as compared with clopidogrel. The risk of bleeding using a combination of GPI and oral antiplatelet regimens is mainly related to the use of GPI and not the oral antiplatelet regimen. Considering the absence of increased risk of bleeding and the persistence of the benefit of recent P2Y₁₂ regimens in combination with GPI as compared with the standard clopidogrel regimen, the use of such a combination within the guidelines is supported by our findings.     

普拉格雷的合成工艺研究

目的：优化抗凝血药普拉格雷的合成工艺。方法：以2-噻吩乙胺为原料与多聚甲醛反应得到4,5,6,7-四氢噻唑[3,2-c]吡啶（3）,3被三苯甲基保护后用丁基锂拔掉噻吩α位氢,经硼化、氧化、脱保护得到关键中间体2-氧-2,4,5,6,7,7a-六氢噻唑[3,2-c]吡啶（6）;邻氟苯乙酸与环丙烷甲酸甲酯反应得到环丙基-2-氟苄基酮（8）,8溴代得到关键中间体α-环丙基羰基-2-氟苄基溴（9）;6与9缩合后乙酰化得到目标化合物。结果：本研究革除了原文献中剧毒的溶剂、试剂,缩短了合成路线,简化了操作,合成总收率由文献的35.5%提高到72.9%。结论：本方法操作简单,收率高,适合工业化生产。     

Personalizing antiplatelet prescribing using genetics for patients undergoing percutaneous coronary intervention

Introduction. Clopidogrel is commonly prescribed with aspirin to reduce the risk for adverse cardiovascular events after percutaneous coronary intervention (PCI). However, there is significant inter-patient variability in clopidogrel response. The CYP2C19 enzyme is involved in the biotransformation of clopidogrel to its pharmacologically active form, and variation in the CYP2C19 gene contributes to clopidogrel response variability.

Areas covered. This article describes the impact of CYP2C19 genotype on clopidogrel pharmacokinetics, pharmacodynamics, and effectiveness. Examples of clinical implementation of CYP2C19 genotype-guided antiplatelet therapy for patients undergoing PCI are also described as are emerging outcomes data with this treatment approach.

Expert commentary. A large clinical trial evaluating outcomes with CYP2C19 genotype-guided antiplatelet therapy after PCI is on-going. In the meantime, data from pragmatic and observational studies and smaller trials support improved outcomes with genotyping after PCI and use of alternative antiplatelet therapy in patients with a CYP2C19 genotype associated with reduced clopidogrel effectiveness.     

A noninferiority confirmatory trial of prasugrel versus clopidogrel in Japanese patients with non-cardioembolic stroke: rationale and study design for a randomized controlled trial – PRASTRO-I trial

Background: This comparison of PRAsugrel and clopidogrel in Japanese patients with ischemic STROke (PRASTRO)-I trial investigates the noninferiority of prasugrel to clopidogrel sulfate in the prevention of recurrence of primary events (ischemic stroke, myocardial infarction, and death from other vascular causes), and the long-term safety of prasugrel in Japanese patients with non-cardioembolic stroke.

Research design and methods: This was an active-controlled, randomized, double-blind, double-dummy, parallel-group study conducted between July 2011 and March 2016 at multiple centers around Japan. Patients had to meet eligibility criteria before receiving 3.75 mg prasugrel or 75 mg clopidogrel orally once daily for a period of 96–104 weeks.

Results: A total of 3747 patients were included in this trial; 1598 in the 3.75 mg prasugrel group and 1551 in the 75 mg clopidogrel group completed the study. During the study period, 287 (15.2%) patients in the prasugrel group and 311 (16.7%) in the clopidogrel group discontinued treatment. Baseline characteristics, safety, and efficacy results are forthcoming and will be published separately.

Conclusions: This article presents the study design and rationale for a trial investigating the noninferiority of prasugrel to clopidogrel sulfate with regards to the inhibitory effect on primary events in patients with non-cardioembolic stroke.     

Evaluating current and emerging antithrombotic therapy currently available for the treatment of acute coronary syndrome in geriatric populations

Introduction: Acute coronary syndromes (ACS) represent one of the most perilous presentations of ischemic heart disease. Temporal trends clearly demonstrate that ACS occur later and later in life. Elderly patients with ACS comprise a populous and growing group, with more than half of individuals presenting with myocardial infarction being 75 years or older. Nevertheless, geriatric patients are greatly underrepresented in the landmark ACS trials evaluating innovative pharmacological strategies.

Areas covered: The authors critically summarize recently published research on contemporary and emerging antithrombotic therapy for the treatment of ACS in geriatric patients.

Expert opinion: Elderly ACS patients are characterized by simultaneously increased risk of cardiovascular events and bleeding. Very few studies assessing the efficacy and safety of novel ACS pharmacotherapy in geriatric patients are currently available. Guidelines on the treatment of ACS are based on the overall results of major randomized clinical trials (RCTs), and data supporting the recommended therapy in elderly mainly derive from subanalyses of these RCTs. Properly designed and powered RCTs are necessary to properly evaluate the net effect of current and emerging pharmacotherapy in geriatric patients. Until such data are available, elderly ACS patients should receive treatment according to the general recommendations.