A head-to-head pharmacodynamic comparison of prasugrel vs. ticagrelor after switching from clopidogrel in patients with coronary artery disease: results of a prospective randomized study.

AIMS: Pharmacodynamic (PD) studies comparing prasugrel and ticagrelor have reached inconsistent findings. Therefore, a comprehensive investigation comparing the PD effects of prasugrel vs. ticagrelor after switching from clopidogrel therapy, exploring both loading dose (LD) and maintenance dose (MD) regimens represented the aim of this study. METHODS AND RESULTS: Patients (n = 110) with coronary artery disease were randomized to prasugrel (60 mg LD/10 mg MD q.d.) or ticagrelor (180 mg LD/90 mg MD b.i.d) therapy for 1 week. Pharmacodynamic assessments were conducted using three assays (vasodilator-stimulated phosphoprotein, VerifyNow P2Y12, and light transmittance aggregometry, LTA) at baseline, 30 min, 2, 24 h, and 1 week. The impact of initiating ticagrelor MD 12 vs. 24 h after LD administration was also assessed. Switching clopidogrel-treated patients to an LD of prasugrel or ticagrelor was associated with a reduction in platelet reactivity at 30 min and was sustained at all time points up to 1 week with the MD (P < 0.001 for all assays). Platelet reactivity was similar with prasugrel and ticagrelor with all assays at 30 min, 2 h, and 1 week (P > 0.05 for all time points), with the exception of LTA at 30 min (lower with prasugrel; P = 0.003). At 24 h, platelet reactivity was lower among patients initiating ticagrelor MD after 12 vs. 24 h post-LD. Rates of high platelet reactivity (HPR) were markedly reduced and similar between groups. CONCLUSION: Prasugrel and ticagrelor exert similar levels of P2Y12 inhibition achieving more potent PD effects and reduced HPR rates compared with clopidogrel which are reached promptly following LD and sustained with MD. CLINICALTRIALSGOV IDENTIFIER: NCT01852175.

Pharmacodynamic effects of EV-077 in patients with diabetes mellitus and coronary artery disease on aspirin or clopidogrel monotherapy: results of an in vitro pilot investigation.

Patients with diabetes mellitus (DM) have increased propensity to generate thromboxane A2 (TXA2) and other eicosanoids which can contribute to their heightened platelet reactivity. EV-077 is a potent thromboxane receptor antagonist and thromboxane synthase inhibitor and thus represents an attractive therapy in patients with DM. However, the effects of EV-077 on pharmacodynamic (PD) profiles in patients with DM and coronary artery disease (CAD) while on antiplatelet therapy is poorly explored and represented the aim of this in vitro pilot investigation. Patients with DM and stable CAD (n = 10) on low-dose aspirin (81 mg/day) were enrolled and then switched to clopidogrel (75 mg/day) monotherapy for 7-10 days. PD assessments were conducted while on aspirin and on clopidogrel using light transmittance aggregometry following stimuli with U-46619 [TXA2 stable analogue (7 µM)], arachidonic acid [AA (1 mM)], collagen (3 µg/mL) and adenosine diphosphate [ADP (5 µM and 20 µM)] with and without in vitro EV-077. EV-077 completely inhibited U-46619-stimulated platelet aggregation (p = 0.005 for both aspirin and clopidogrel) and also showed a significant reduction of collagen-induced aggregation (aspirin p = 0.008; clopidogrel p = 0.005). EV-077 significantly reduced AA-induced platelet aggregation in clopidogrel (p = 0.009), but not aspirin (p = 0.667) treated patients. Ultimately, EV-077 significantly reduced ADP-mediated platelet aggregation in both aspirin (ADP 5 µM p = 0.012; ADP 20 µM p = 0.032) and clopidogrel (ADP 5 µM p = 0.007; ADP 20 µM p = 0.008) treated patients. In conclusion, in DM patients with CAD on aspirin or clopidogrel monotherapy, in vitro EV-077 exerts potent platelet inhibitory effects on multiple platelet signaling pathways. These data support that EV-077 has only additive platelet inhibiting effects on top of standard antiplatelet therapies. These findings warrant further investigation in ex vivo settings.

Pharmacodynamic Effects of Ticagrelor Dosing Regimens in Patients on Maintenance Ticagrelor Therapy: Results From a Prospective, Randomized, Double-Blind Investigation.

OBJECTIVES: The aim of this study was to assess the impact of ticagrelor dosing regimens on pharmacodynamic (PD) profiles in patients on maintenance ticagrelor therapy. BACKGROUND: Many patients on maintenance P2Y12-inhibiting therapies may require coronary revascularization procedures, raising a common clinical question with regard to the dosing regimen of the P2Y12-inhibiting agent to be used. To date, investigations assessing dosing regimens of P2Y12 receptor inhibitors in patients on maintenance therapy have been only assessed with thienopyridines, but not with ticagrelor. METHODS: This was a prospective, randomized, double-blind, placebo-controlled study assessing the PD effects of 2 dosing regimens of ticagrelor in patients on standard aspirin and ticagrelor maintenance therapy. A total of 60 patients were randomized to either 90 mg (maintenance dose [MD] group) or 180 mg (loading dose [LD] group) dose of ticagrelor. PD assessments were conducted at 3 time points (baseline, 1 h and 4 h). PD assessments were defined according to the platelet reactivity index (PRI) (vasodilator-stimulated phosphoprotein phosphorylation assay), P2Y12 reaction unit (VerifyNow P2Y12 assay) and adenosine diphosphate-induced platelet aggregation by light transmittance aggregometry. RESULTS: There were no differences in baseline levels of platelet reactivity with all assays. Intergroup comparisons by means of repeated-measures analysis adjusted for baseline PRI values showed that the LD group had significantly lower PRI levels compared with the MD group during the overall study time course (p = 0.031). Consistent findings were found for P2Y12 reaction unit (p = 0.026) and light transmittance aggregometry (p = 0.004). Intragroup comparisons showed that a more prompt and sustained platelet inhibitory effect was achieved more consistently with an LD regimen compared with a MD regimen. CONCLUSIONS: In patients on maintenance ticagrelor therapy, a 180-mg LD regimen of ticagrelor is associated with more potent and prompt platelet inhibition compared with a 90-mg MD. (Impact of Ticagrelor Re-Load Pharmacodynamic Profiles; NCT01731041).

Use of the radial approach in primary angioplasty: results in 1029 consecutive patients and analyses in unfavorable subgroups.

INTRODUCTION AND OBJECTIVES: The transradial approach is associated with a reduction in vascular access-related complications after primary percutaneous coronary interventions. The purpose of this study was to examine the feasibility of the routine use of transradial access in primary angioplasty and to evaluate how it affects subgroups with less favorable characteristics. METHODS: We analyzed 1029 consecutive patients with an ST-segment elevation acute coronary syndrome treated with primary angioplasty. RESULTS: Transradial access was the primary approach in 93.1% of the patients. The success rate of primary angioplasty was 95.9%, and 87.6% of the patients were event-free 30 days after the procedure. Crossover was required in 3.0% of the patients with primary transradial access, and this rate remained stable over the years. Predictors of the need for crossover were age older than 75 years (odds ratio=2.50, 95% confidence interval, 1.09-5.71; P=.03) and a history of ischemic heart disease (odds ratio=2.65; 95% confidence interval, 1.12-6.24; P=.02). Primary transfemoral access use was higher in women older than 75 years. Use of the transradial approach in this subgroup did not affect reperfusion time or the success of angioplasty, although there was a greater need for crossover (10.9% vs 2.6%; P=.006). Among patients in cardiogenic shock, the transradial approach was used in 51.5%; reperfusion times and angioplasty success rates were similar to those obtained with transfemoral access, but there was a greater need for crossover. CONCLUSIONS: Transradial access can be used safely and effectively in most primary angioplasty procedures. In older women and in patients in cardiogenic shock, there is a higher crossover requirement, with no detriment to reperfusion time.

Impact of cigarette smoking on P2Y12 receptor binding activity before and after clopidogrel therapy in patients with coronary artery disease.

Smoking enhances the P2Y12 receptor inhibitory effects of clopidogrel. Nicotine increases P2Y12 receptor expression in platelet lysates from healthy volunteers. However, the impact of cigarette smoking on platelet P2Y12 receptor binding in clopidogrel-treated patients with coronary artery disease (CAD) is unknown. Clopidogrel-naïve patients with stable CAD (n = 20) were enrolled and stratified according to smoking status. P2Y12 receptor binding activity was determined by radioligand receptor binding prior and 24 h after a 600-mg loading dose of clopidogrel. Baseline P2Y12 receptor binding was 1.8-fold higher in smokers compared with nonsmokers. After a 600-mg loading dose of clopidogrel, smokers showed a 6.4-fold reduction in P2Y12 receptor binding indicative of marked clopidogrel-mediated blockade, while there were minimal changes among nonsmokers. Among patients with stable CAD, smokers have more P2Y12 receptor binding than nonsmokers and have a higher degree of clopidogrel-mediated platelet inhibition.

Pharmacodynamic effects of cangrelor on platelet P2Y12 receptor-mediated signaling in prasugrel-treated patients.

OBJECTIVES: The purpose of this study was to assess the in vitro P2Y12 receptor inhibitory effects of cangrelor on platelets from patients on maintenance prasugrel therapy treated with 2 reloading dose regimens. BACKGROUND: Despite its more potent and rapid antiplatelet effects compared with clopidogrel, recent studies have shown variability in prasugrel-mediated P2Y12 receptor inhibition, particularly in high-risk settings. Cangrelor is a potent intravenous P2Y12 receptor inhibitor. METHODS: A total of 60 patients with coronary artery disease on maintenance prasugrel (10 mg/day) therapy were randomized to a 30- or 60-mg reload of prasugrel. The platelet reactivity index (PRI), as assessed by whole-blood vasodilator-stimulated phosphoprotein, was measured with and without in vitro incubation of cangrelor (500 nM) at baseline, and at 1 and 4 h after reload. RESULTS: In the absence of cangrelor, prasugrel reloading reduced PRI (p < 0.001 for both doses), although a 60-mg reload had greater platelet inhibition compared with a 30-mg reload at 4 h (p = 0.001). Cangrelor was associated with a reduction in PRI values during the overall study time course in patients reloaded with 30 mg (p = 0.001) and 60 mg (p < 0.001) of prasugrel. In patients reloaded with 30 mg prasugrel, cangrelor decreased PRI at each time point (baseline, p < 0.001; 1 h, p = 0.013; 4 h, p = 0.001). In patients reloaded with 60 mg prasugrel, cangrelor decreased PRI at baseline (p < 0.001) and 1 h (p = 0.002); levels of platelet reactivity comparable to those achieved with cangrelor were observed only at 4 h (p = 0.325). The intergroup comparisons with cangrelor were not significant at any time point. CONCLUSIONS: In patients on maintenance prasugrel therapy exposed to a reloading dose (30 or 60 mg) of prasugrel, in vitro cangrelor is associated with further platelet P2Y12 receptor inhibitory effects.

Cigarette smoking and antiplatelet effects of aspirin monotherapy versus clopidogrel monotherapy in patients with atherosclerotic disease: results of a prospective pharmacodynamic study.

Smokers have a greater relative benefit of clopidogrel therapy compared with nonsmokers, likely attributed to its enhanced pharmacodynamic (PD) effects. However, to date, all PD studies have been conducted in patients on dual antiplatelet therapy with aspirin and clopidogrel, and it is unknown whether clopidogrel monotherapy can offer more effective antithrombotic effects compared with aspirin alone among smoking patients. Sixty aspirin-treated (81 mg/day) patients with vascular disease, classified as nonsmokers, light smokers, and heavy smokers according to cotinine serum levels, were enrolled. Patients were switched to clopidogrel (75 mg/day) monotherapy for 7-10 days. PD assessments were performed before and after switch by multiple electrode aggregometry (MEA) and kaolin-activated thromboelastography (TEG). Complete PD data were obtained in 57 patients (nonsmokers, n = 27; light smokers, n = 13; heavy smokers, n = 17). On treatment platelet reactivity following MEA, adenosine diphosphate (ADP) + prostaglandin E1 (PGE1) and thrombin receptor-activating peptide (TRAP) stimuli were significantly lower among heavy smokers following switch to clopidogrel. A significant inverse effect was observed with MEA arachidonic acid (ASPI), while neutral findings were shown with MEA collagen (COLL) stimulus. Thrombin and fibrin activity assessed by clot generation parameters were all nonsignificantly different but showed trends towards enhanced antithrombotic activity with clopidogrel among heavy smokers. In heavy smokers with vascular disease manifestations, clopidogrel is associated with enhanced platelet inhibitory effects, affecting purinergic and non-purinergic pathways, compared with aspirin as measured by MEA. Moreover, among smokers, clopidogrel offers trends towards enhanced effects on parameters of clot generation measured by TEG.

Platelet function profiles in patients with diabetes mellitus.

Patients with diabetes mellitus (DM) are at high risk for several cardiovascular disorders such as coronary heart disease, stroke, peripheral arterial disease, and congestive heart failure. DM has reached epidemic proportions and its strong association with coronary artery disease is responsible for increased cardiovascular morbidity and mortality. DM patients are characterized by platelet hyperreactivity, which contribute to the enhanced atherothrombotic risk of these subjects. Several mechanisms are involved in the hyperreactive platelet phenotype characterizing DM patients. Furthermore, a large proportion of DM patients show inadequate response to standard antiplatelet treatments and high rate of adverse recurrent cardiovascular events despite compliance with standard antiplatelet treatment regimens. Therefore, new antiplatelet treatment regimens are warranted in DM patients to reduce their atherothrombotic risk. The present manuscript provides an overview on the current status of knowledge on platelet function profiles in patients with DM and therapeutic considerations.

Update on platelet glycoprotein IIb/IIIa inhibitors: recommendations for clinical practice.

Antiplatelet therapy is the cornerstone of treatment for patients with acute coronary syndrome (ACS) and undergoing percutaneous coronary intervention (PCI). Glycoprotein IIb/IIIa receptors mediate platelet aggregation, representing the final common pathway of platelet-mediated thrombosis. Therefore, agents blocking this pathway may be desirable for the treatment of patients with ACS and PCI. Glycoprotein IIb/IIIa receptor inhibitors have been widely investigated and have been key to the pharmacological advancements in the field. However, although GPIs have been important to reduce ischemic complications, their elevated risk of bleeding complications remains a major limitation. The poor prognostic implications, including increased mortality, associated with bleeding complication underscores the need for alternative treatment options. Over the past years there have been several advancements in antithrombotic pharmacology which have led to changes in recommendations for GPI usage in clinical practice. This is an overview of the most recent clinical trial data on GPIs, and provides practical insight on their modern day use in ACS therapy.

Cangrelor: a review on pharmacology and clinical trial development.

Dual antiplatelet therapy with aspirin and an oral ADP P2Y12 receptor antagonist is the standard-of-care for the prevention of ischemic events in patients with acute coronary syndrome or undergoing percutaneous coronary intervention (PCI). However, currently available ADP P2Y12 receptor antagonists have several limitations, such as interindividual response variability, drug-drug interactions, slow onset/offset and only oral availability. Cangrelor is a reversible, potent, intravenous, competitive inhibitor of the ADP P2Y12 receptor that rapidly achieves near complete and predictable platelet inhibition. Along with reversible binding to the receptor cangrelor also has a very short half-life (3-5 min), which in turn results in a rapid offset of action. These properties make cangrelor a promising drug for clinical use in patients undergoing PCI or patients waiting for major surgery but still require antiplatelet protection. This manuscript provides an update of the current status of knowledge on cangrelor, focusing on its pharmacologic properties and clinical trial development, including the BRIDGE and CHAMPION-PHOENIX trials.

Impact of aspirin dose on adenosine diphosphate-mediated platelet activities. Results of an in vitro pilot investigation.

Different aspirin dosing regimens have been suggested to impact outcomes when used in combination with adenosine diphosphate (ADP) P2Y12 receptor antagonists. Prior investigations have shown that not only aspirin, but also potent ADP P2Y12 receptor blockade can inhibit thromboxane A2-mediated platelet activation. The impact of aspirin dosing on ADP mediated platelet activities is unknown and represents the aim of this in vitro pilot pharmacodynamic (PD) investigation. Twenty-six patients with stable coronary artery disease on aspirin 81 mg/day and P2Y12 naïve were enrolled. PD assessments were performed at baseline, while patients were on 81 mg/day aspirin and after switching to 325 mg/day for 7 ± 2 days with and without escalating concentrations (vehicle, 1, 3, and 10 µM) of prasugrel's active metabolite (P-AM). PD assays included flow cytometric assessment of VASP to define the platelet reactivity index (PRI) and the Multiplate Analyzer (MEA) using multiple agonists [ADP, ADP + prostaglandin (PGE1), arachidonic acid (AA), and collagen]. Escalating P-AM concentrations showed incremental platelet P2Y12 inhibition measured by VASP-PRI (p<0.001). However, there were no differences according to aspirin dosing regimen at any P-AM concentration (vehicle: p=0.899; 1 µM: p=0.888; 3 µM: p=0.524; 10 µM: p=0.548). Similar findings were observed in purinergic markers assessed by MEA (ADP and ADP+PGE1). P-AM addition significantly reduced AA and collagen induced platelet aggregation (p<0.001 for all measures), irrespective of aspirin dose. In conclusion, aspirin dosing does not appear to affect PD measures of ADP-mediated platelet reactivity irrespective of the degree of P2Y12 receptor blockade. P2Y12 receptor blockade modulates platelet reactivity mediated by alternative activators.

El uso del acceso radial en la angioplastia primaria: resultados en 1.029 pacientes consecutivos y análisis en subgrupos desfavorables / Use of the radial approach in primary angioplasty: results in 1029 consecutive patients and analyses in unfavorable subgroups

INTRODUCCIÓN Y OBJETIVO:S: El acceso radial reduce las complicaciones vasculares tras la angioplastia primaria. El objetivo es examinar la factibilidad del acceso radial sistemático en la angioplastia primaria y evaluar cómo afecta a los subgrupos menos favorables. MÉTODOS: Se ha analizado a 1.029 pacientes consecutivos con síndrome coronario agudo con elevación del segmento ST tratados con angioplastia primaria. RESULTADOS: En el 93,1% de los pacientes, el acceso radial ha sido el acceso primario. La tasa de éxito de angioplastia primaria fue del 95,9%, y el 87,6% de los pacientes estaban libres de eventos clínicos a los 30 días del procedimiento. La tasa de cruce vascular fue del 3,0%, estable durante el periodo estudiado. La edad mayor de 75 años (odds ratio = 2,50; intervalo de confianza del 95%, 1,09-5,71; p = 0,03) y la historia de cardiopatía isquémica previa (odds ratio = 2,65, intervalo de confianza del 95%, 1,12-6,24; p = 0,02) fueron predictores de necesidad de cruce. En las mujeres y los mayores de 75 años, el uso del acceso femoral primario fue mayor. Sin embargo, en este subgrupo de pacientes el acceso radial no afectó a los tiempos de reperfusión ni al éxito de la angioplastia, aunque sí se observó una mayor tasa de cruce (el 10,9 frente al 2,6%; p = 0,006). En los pacientes en shock cardiogénico, el acceso radial se utilizó en el 51,5% de los casos, con tiempos de reperfusión y tasas de éxito de la angioplastia similares a los del acceso femoral, aunque con mayor necesidad de cruce. CONCLUSIONES: El acceso radial se puede utilizar de manera segura y eficaz en la mayoría de las angioplastias primarias. En mujeres de edad avanzada y en pacientes en shock, aumenta la necesidad de cruce sin penalizar los tiempos de reperfusión

INTRODUCTION AND OBJECTIVES: The transradial approach is associated with a reduction in vascular access-related complications after primary percutaneous coronary interventions. The purpose of this study was to examine the feasibility of the routine use of transradial access in primary angioplasty and to evaluate how it affects subgroups with less favorable characteristics. METHODS: We analyzed 1029 consecutive patients with an ST-segment elevation acute coronary syndrome treated with primary angioplasty. RESULTS: Transradial access was the primary approach in 93.1% of the patients. The success rate of primary angioplasty was 95.9%, and 87.6% of the patients were event-free 30 days after the procedure. Crossover was required in 3.0% of the patients with primary transradial access, and this rate remained stable over the years. Predictors of the need for crossover were age older than 75 years (odds ratio=2.50, 95% confidence interval, 1.09-5.71; P=.03) and a history of ischemic heart disease (odds ratio=2.65; 95% confidence interval, 1.12-6.24; P=.02). Primary transfemoral access use was higher in women older than 75 years. Use of the transradial approach in this subgroup did not affect reperfusion time or the success of angioplasty, although there was a greater need for crossover (10.9% vs 2.6%; P=.006). Among patients in cardiogenic shock, the transradial approach was used in 51.5%; reperfusion times and angioplasty success rates were similar to those obtained with transfemoral access, but there was a greater need for crossover. CONCLUSIONS: Transradial access can be used safely and effectively in most primary angioplasty procedures. In older women and in patients in cardiogenic shock, there is a higher crossover requirement, with no detriment to reperfusion time