Reduction in Platelet Reactivity With Prasugrel 5 mg in Low-Body-Weight Patients Is Noninferior to Prasugrel 10 mg in Higher-Body-Weight Patients

Pharmacokinetic/Pharmacodynamic Assessment of the Structural Refinement of Clopidogrel Focusing on the Balance between Bioactivation and Deactivation

The delicate balance between ischemic and bleeding risks is a critical factor in antiplatelet therapy administration. Clopidogrel and prasugrel, belonging to the thienopyridine class of antiplatelet drugs, are known for their variability in individual responsiveness and high incidence of bleeding events, respectively. The present study is centered on the development and assessment of a range of deuterated thienopyridine derivatives, leveraging insights from structure-pharmacokinetic relationships of clopidogrel and prasugrel. Our approaches were grounded in the molecular framework of clopidogrel and incorporated the C2-pharmacophore design from prasugrel. The selection of ester or carbamate substituents at the C2-position facilitated the generation of the 2-oxointermediate through hydrolysis, akin to prasugrel, thereby bypassing the issue of CYP2C19 dependency. The bulky C2-pharmacophore in our approach distinguishes itself from prasugrel's acetyloxy substituent by exhibiting a moderated hydrolysis rate, resulting in a more gradual formation of the active metabolite. Excessive and rapid release of the active metabolite, believed to be linked with an elevated risk of bleeding, is thus mitigated. Our proposed structural modification retains the hydrolysis-sensitive methyl ester of clopidogrel but substitutes it with a deuterated methyl group, shown to effectively reduce metabolic deactivation. Three promising compounds demonstrated a pharmacokinetic profile similar to that of clopidogrel at four times the dose, while also augmenting its antiplatelet activity. SIGNIFICANCE STATEMENT: Inspired by the structure-pharmacokinetic relationship of clopidogrel and prasugrel, a range of clopidogrel derivatives were designed, synthesized, and assessed. Among them, three promising compounds have been identified, striking a delicate balance between efficacy and safety for antiplatelet therapy. Additionally, the ozagrel prodrug conjugate was discovered to exert a synergistic therapeutic effect alongside clopidogrel.

Current Strategies to Guide the Antiplatelet Therapy in Acute Coronary Syndromes

The role of antiplatelet therapy in patients with acute coronary syndromes is a moving target with considerable novelty in the last few years. The pathophysiological basis of the treatment depends on platelet biology and physiology, and the interplay between these aspects and clinical practice must guide the physician in determining the best therapeutic options for patients with acute coronary syndromes. In the present narrative review, we discuss the latest novelties in the antiplatelet therapy of patients with acute coronary syndromes. We start with a description of platelet biology and the role of the main platelet signal pathways involved in platelet aggregation during an acute coronary syndrome. Then, we present the latest evidence on the evaluation of platelet function, focusing on the strengths and weaknesses of each platelet's function test. We continue our review by describing the role of aspirin and P2Y12 inhibitors in the treatment of acute coronary syndromes, critically appraising the available evidence from clinical trials, and providing current international guidelines and recommendations. Finally, we describe alternative therapeutic regimens to standard dual antiplatelet therapy, in particular for patients at high bleeding risk. The aim of our review is to give a comprehensive representation of current data on antiplatelet therapy in patients with acute coronary syndromes that could be useful both for clinicians and basic science researchers to be up-to-date on this complex topic.

Low-dose prasugrel versus standard-dose ticagrelor in east Asian patients with acute coronary syndrome

Low-dose prasugrel demonstrated a similar effectiveness profile to clopidogrel in East Asian ACS patients, but its comparison with another new-generation potent P2Y12 inhibitor, ticagrelor, remains unclear. To compare the effectiveness and safety of low-dose prasugrel against those of standard-dose ticagrelor in East Asian patients with ACS. This retrospective cohort study used Taiwan's National Health and Welfare Database. This study included ACS patients who underwent percutaneous coronary intervention and, at discharge between January 1, 2018 and December 31, 2020, were prescribed with low-dose prasugrel plus aspirin or standard-dose ticagrelor plus aspirin. Stabilized inverse probability of treatment weighting was used to balance the covariates across these two groups. The primary effectiveness outcome was a composite of acute myocardial infarction, ischemic stroke, and cardiovascular death; the secondary effectiveness outcome was each of the individual components of the primary outcome, transient ischemic attack, and repeat revascularization. The primary safety outcome was a composite of intracranial hemorrhage and gastrointestinal bleeding, and the two secondary safety outcomes were intracranial hemorrhage and gastrointestinal bleeding. A total of 24,807 patients were included in this study. Among them, 1,493 were low-dose prasugrel users and 23,314 were standard-dose ticagrelor users. No significant differences were found in primary effectiveness [HR: 0.97 (0.74-1.28)] or primary safety outcomes [HR: 1.22 (0.73-2.01)] between the two study groups. For East Asian patients with ACS, low-dose prasugrel provides comparable effectiveness without increasing bleeding risk compared to standard-dose ticagrelor. Low-dose prasugrel may be an appropriate alternative for East Asian populations.

Antiplatelet Therapy in Neurointervention

The aim of this review is to provide an overview of the use of antiplatelet medication in neurointervention, with a focus on the clinical indications for antiplatelet use in both preventing and reducing platelet aggregation. This review will cover current antiplatelet medications, pharmacokinetics, and pharmacodynamics. We will provide an overview of different endovascular devices and discuss the antiplatelet regimes in neurointervention, highlighting gaps in evidence and scope for future studies.Two randomized controlled trials have evaluated antiplatelet use in the setting of acute large vessel occlusion stroke, with neither demonstrating benefit in their overall cohorts. Evidence on antiplatelet medication for both acute and elective stenting for acute stroke and treatment of cerebral aneurysms is currently based on large case series, and practice in neurointervention has increasingly utilized dual antiplatelet regimes with clopidogrel and second-line agents like prasugrel and ticagrelor. Clopidogrel function testing has an increasing role in neurointerventional procedures, particularly for high metal surface area stents such as the braided flow diverter type stents. Intravenous glycoprotein IIB/IIIA inhibitors have been utilized for both acute bridging and rescue therapy.Antiplatelet decision making is complex, and there are few randomized control trials to guide clinical practice. Comparative trials to guide decision making remain important in both the acute and elective settings. Standardised protocols incorporating platelet function testing may play a role in assisting decision making until more robust clinical evidence is available, particularly in the context of acute neurointerventional stenting for stroke and ruptured cerebral aneurysms.

Antiplatelet therapy after percutaneous coronary intervention

Antiplatelet therapy is key to reducing local thrombotic complications and systemic ischaemic events among patients undergoing percutaneous coronary interventions (PCI), but it is inevitably associated with increased bleeding. The continuous refinement in stent technologies, together with the high incidence of ischaemic recurrences after PCI and the understanding of prognostic implications associated with bleeding, have led to a substantial evolution in antiplatelet treatment regimens over the past decades. Numerous investigations have been conducted to better stratify patients undergoing PCI according to their ischaemic and bleeding risks and to implement antithrombotic regimens accordingly. Evidence from these investigations have resulted in a number of antithrombotic treatment options as recommended by recent guidelines. In this State-of-the-Art review we provide the rationale, summarise the evidence, and discuss current and future directions of antiplatelet treatment regimens after PCI.

Evolution of antithrombotic therapy in patients undergoing percutaneous coronary intervention: a 40-year journey

Since its introduction in 1977, percutaneous coronary intervention has become one of the most commonly performed therapeutic procedures worldwide. Such widespread diffusion, however, would have not been possible without a concomitant evolution of the pharmacotherapies associated with this intervention. Antithrombotic agents are fundamental throughout the management of patients undergoing coronary stent implantation, starting from the procedure itself to the long-term prevention of cardiovascular events. The last 40 years of interventional cardiology have seen remarkable improvements in both drug therapies and device technologies, which largely reflected a progressive understanding of the pathophysiological mechanisms of coronary artery disease, as well as procedure- and device-related adverse events. The purpose of this article is to provide an overview of the important milestones in antithrombotic pharmacology that have shaped clinical practice of today while also providing insights into knowledge gaps and future directions.

Antithrombotic treatment in primary percutaneous coronary intervention

INTRODUCTION

Despite a timely mechanical reperfusion with primary percutaneous coronary intervention (pPCI) patients presenting with ST-elevation myocardial infarction (STEMI) display an increased risk of adverse cardiovascular events. Several studies have demonstrated that guideline-directed antithrombotic therapy is effective to reduce this risk. However, there is still much to be accomplished to improve antithrombotic therapies in this clinical setting.

AREAS COVERED

This paper reviews current data on antithrombotic therapy in STEMI patients undergoing pPCI.

EXPERT OPINION

Antithrombotic therapy for STEMI patients undergoing pPCI should take into account the variability of thrombotic and bleeding risk in the short and long term. Patients with STEMI profit from the administration of early onset antiplatelet agents and anticoagulation to achieve sufficient and predictable antithrombotic effect at the time of pPCI. Thereafter, antithrombotic therapies should be tailored to individual risk of recurrence over the long term, to avoid excess bleeding, while ensuring adequate secondary ischemic prevention.

Complexity of Antiplatelet Therapy in Coronary Artery Disease Patients

Patients with coronary artery disease (CAD) presenting with acute coronary syndrome or undergoing coronary stenting are indicated to treatment with dual antiplatelet therapy (DAPT) combining aspirin with a P2Y12 receptor inhibitor. The management of patients with CAD who present with a complex clinical profile due to multiple comorbidities, and/or undergoing complex interventional procedures, remains challenging as a high risk for both ischemic and bleeding events is often present; hence, the risk-benefit balance on the optimal DAPT duration is difficult to evaluate. The complexity of antiplatelet therapy in CAD patients is due to the fact that this complexity embraces several aspects: the coronary anatomy, the number of vascular districts at risk for atherothrombosis, and patient comorbidities, including global frailty. Recent randomized and epidemiological studies have highlighted subgroups that could benefit from prolonged antithrombotic treatment, as well as frail patients, who may be better suited to a shorter course of therapy. We provide an overview of the current knowledge regarding treatment with DAPT, along with suggestions on its management.

Age- and Weight-Adapted Dose of Prasugrel Versus Standard Dose of Ticagrelor in Patients With Acute Coronary Syndromes : Results From a Randomized Trial

BACKGROUND

The efficacy and safety of a reduced dose of prasugrel versus a standard dose of ticagrelor in elderly patients or those with a low body weight presenting with an acute coronary syndrome (ACS) are unknown.

OBJECTIVE

To investigate the effect of an age- and weight-adapted dose of prasugrel versus a standard dose of ticagrelor in patients with ACS. (ClinicalTrials.gov: NCT01944800).

DESIGN

Prespecified analysis of the multicenter, randomized ISAR-REACT 5 trial.

SETTING

23 centers in Germany and Italy.

PATIENTS

3997 patients with ACS planned for invasive management.

INTERVENTION

Participants were randomly assigned to receive a standard dose of ticagrelor or prasugrel (reduced dose in the elderly or low-weight group and standard dose in the neither elderly nor low-weight group).

MEASUREMENTS

The efficacy end point was a composite of death, myocardial infarction, or stroke, and the safety end point was bleeding, both at 12 months.

RESULTS

In the elderly or low-weight group, the efficacy end point occurred in 12.7% of patients assigned to receive prasugrel and 14.6% of those assigned to receive ticagrelor (hazard ratio [HR], 0.82 [95% CI, 0.60 to 1.14]); in the neither elderly nor low-weight group, the efficacy end point occurred in 4.8% of patients assigned to receive prasugrel and 7.3% of those assigned to receive ticagrelor (HR, 0.65 [CI, 0.48 to 0.88]; P for interaction > 0.2). In the elderly or low-weight group, Bleeding Academic Research Consortium type 3 to 5 bleeding occurred in 8.1% of patients assigned to receive prasugrel and 10.6% of those assigned to receive ticagrelor (HR, 0.72 [0.46 to 1.12]), and in 3.7% and 3.8%, respectively, of patients in the neither elderly nor low-weight group (HR, 0.98 [CI, 0.65 to 1.47]; P for interaction > 0.2).

LIMITATION

The study is a subgroup analysis.

CONCLUSION

In elderly or low-weight patients with ACS, a reduced dose of prasugrel compared with the standard dose of ticagrelor is associated with maintained anti-ischemic efficacy while protecting these patients against the excess risk for bleeding.

PRIMARY FUNDING SOURCE

German Center for Cardiovascular Research and Deutsches Herzzentrum München.

Efficacy and safety of vorapaxar for secondary prevention in low body weight in patients with atherosclerosis: analyses from the TRA 2°P-TIMI 50 Trial

BACKGROUND

Vorapaxar inhibits the thrombin-mediated activation of platelets, reduces thrombotic events in patients with myocardial infarction or peripheral arterial disease while increasing bleeding. In the TRA 2°P-TIMI 50 trial, we observed a nominally significant interaction between low body weight and the reduced efficacy of vorapaxar.

METHODS

We investigated the relationship between body weight and the efficacy and safety of vorapaxar within a multinational, randomized, double-blind, placebo-controlled trial of vorapaxar in patients with atherosclerosis. This analysis was performed among 20,138 patients with a clinical indication for vorapaxar.

RESULTS

Compared with patients weighing 60 kg or more, patients weighing less than 60 kg were older, more frequently women, Asian and had renal insufficiency (each P<0.001). The efficacy of vorapaxar with respect to cardiovascular death, myocardial infarction and stroke showed a significant interaction with patients' weight (Pinteraction<0.03). However among patients younger than 65 years, vorapaxar reduced the primary endpoint regardless of weight (weight ≥60 kg: 6.4% vs. 8.1%, hazard ratio (HR) 0.75, 95% confidence interval (CI) 0.65-0.86; weight <60 kg: 5.4% vs. 7.2%, HR 0.75, 95% CI 0.37-1.49, Pinteraction=0.98). Among patients aged 65 years and older, the efficacy of vorapaxar diminished in patients weighing less than 60 kg (high weight: 10.4% vs. 12.6%, HR 0.81, 95% CI 0.69-0.95; low weight: 16.1% vs. 9.0%, HR 1.62, 95% CI 0.95-2.76, Pinteraction=0.01). The relative increase in bleeding with vorapaxar was not modified by weight (all Pinteraction>0.05).

CONCLUSIONS

Vorapaxar reduced vascular events and improved net clinical outcome regardless of body weight in younger patients. Elderly patients with low weight may not be good candidates for aggressive secondary prevention with vorapaxar added to standard therapy.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov Unique identifier: NCT00526474.

Periprocedural Neuroendovascular Antiplatelet Strategies for Thrombosis Prevention in Clopidogrel-Hyporesponsive Patients

Patients undergoing neuroendovascular procedures such as cerebral aneurysm coiling and intracranial stent deployment are frequently treated with antiplatelet agents to prevent thrombotic complications. The combination of aspirin and a P2Y12 inhibitor such as clopidogrel is often initiated days before elective procedures or as loading doses for emergent procedures; however, some patients may still experience thrombotic complications. Patients identified as clopidogrel hyporesponders are more likely to experience poor outcomes and may require changes to their regimens. Historically, high-dose clopidogrel regimens were used in response to subtherapeutic results of platelet function assays and point-of-care testing despite limited supporting data. Recently, more data have emerged using alternative P2Y12 inhibitors such as prasugrel and ticagrelor. Dosing for neuroendovascular conditions is often extrapolated from the cardiac literature, although outcomes in cardiac patients may not be relevant to neurologic patients, making prophylactic treatment recommendations challenging for these patients. This review summarizes the literature for antiplatelet prophylaxis in patients undergoing neuroendovascular device placement, focusing on alternative regimens for clopidogrel hyporesponders.

Effects of aspirin on risks of vascular events and cancer according to bodyweight and dose: analysis of individual patient data from randomised trials

BACKGROUND

A one-dose-fits-all approach to use of aspirin has yielded only modest benefits in long-term prevention of cardiovascular events, possibly due to underdosing in patients of large body size and excess dosing in patients of small body size, which might also affect other outcomes.

METHODS

Using individual patient data, we analysed the modifying effects of bodyweight (10 kg bands) and height (10 cm bands) on the effects of low doses (≤100 mg) and higher doses (300-325 mg or ≥500 mg) of aspirin in randomised trials of aspirin in primary prevention of cardiovascular events. We stratified the findings by age, sex, and vascular risk factors, and validated them in trials of aspirin in secondary prevention of stroke. Additionally, we assessed whether any weight or height dependence was evident for the effect of aspirin on 20-year risk of colorectal cancer or any in-trial cancer.

RESULTS

Among ten eligible trials of aspirin in primary prevention (including 117 279 participants), bodyweight varied four-fold and trial median weight ranged from 60·0 kg to 81·2 kg (p<0·0001). The ability of 75-100 mg aspirin to reduce cardiovascular events decreased with increasing weight (pinteraction=0·0072), with benefit seen in people weighing 50-69 kg (hazard ratio [HR] 0·75 [95% CI 0·65-0·85]) but not in those weighing 70 kg or more (0·95 [0·86-1·04]; 1·09 [0·93-1·29] for vascular death). Furthermore, the case fatality of a first cardiovascular event was increased by low-dose aspirin in people weighing 70 kg or more (odds ratio 1·33 [95% CI 1·08-1·64], p=0·0082). Higher doses of aspirin (≥325 mg) had the opposite interaction with bodyweight (difference pinteraction=0·0013), reducing cardiovascular events only at higher weight (pinteraction=0·017). Findings were similar in men and women, in people with diabetes, in trials of aspirin in secondary prevention, and in relation to height (pinteraction=0·0025 for cardiovascular events). Aspirin-mediated reductions in long-term risk of colorectal cancer were also weight dependent (pinteraction=0·038). Stratification by body size also revealed harms due to excess dosing: risk of sudden death was increased by aspirin in people at low weight for dose (pinteraction=0·0018) and risk of all-cause death was increased in people weighing less than 50 kg who were receiving 75-100 mg aspirin (HR 1·52 [95% CI 1·04-2·21], p=0·031). In participants aged 70 years or older, the 3-year risk of cancer was also increased by aspirin (1·20 [1·03-1·47], p=0·02), particularly in those weighing less than 70 kg (1·31 [1·07-1·61], p=0·009) and consequently in women (1·44 [1·11-1·87], p=0·0069).

INTERPRETATION

Low doses of aspirin (75-100 mg) were only effective in preventing vascular events in patients weighing less than 70 kg, and had no benefit in the 80% of men and nearly 50% of all women weighing 70 kg or more. By contrast, higher doses of aspirin were only effective in patients weighing 70 kg or more. Given that aspirin's effects on other outcomes, including cancer, also showed interactions with body size, a one-dose-fits-all approach to aspirin is unlikely to be optimal, and a more tailored strategy is required.

FUNDING

Wellcome Trust and National Institute for Health Research Oxford Biomedical Research Centre.

Role of genetic testing in patients undergoing percutaneous coronary intervention

INTRODUCTION

Variability in individual response profiles to antiplatelet therapy, in particular clopidogrel, is a well-established phenomenon. Genetic variations of the cytochrome P450 (CYP) 2C19 enzyme, a key determinant in clopidogrel metabolism, have been associated with clopidogrel response profiles. Moreover, the presence of a CYP2C19 loss-of-function allele is associated with an increased risk of atherothrombotic events among clopidogrel-treated patients undergoing percutaneous coronary interventions (PCI), prompting studies evaluating the use of genetic tests to identify patients who may be potential candidates for alternative platelet P2Y12 receptor inhibiting therapies (prasugrel or ticagrelor). Areas covered: The present manuscript provides an overview of genetic factors associated with response profiles to platelet P2Y12 receptor inhibitors and their clinical implications, as well as the most recent developments and future considerations on the role of genetic testing in patients undergoing PCI. Expert commentary: The availability of more user-friendly genetic tests has contributed towards the development of many ongoing clinical trials and personalized medicine programs for patients undergoing PCI. Results of pilot investigations have shown promising results, which however need to be confirmed in larger-scale studies to support the routine use of genetic testing as a strategy to personalize antiplatelet therapy and improve clinical outcomes.

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

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 [CI]: 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 VNPRU, 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.

Pharmacodynamic effects of standard dose prasugrel versus high dose clopidogrel in non-diabetic obese patients with coronary artery disease

Increased body weight is independently associated with impaired clopidogrel pharmacodynamic (PD) response. Prasugrel has more potent PD effects compared with clopidogrel, although its PD effects in obese patients are unknown. The aim of this prospective, randomised, study was to compare the PD effects of standard-dose prasugrel [60 mg loading dose (LD)/10 mg daily maintenance dose (MD)] with highdose clopidogrel (900 mg LD/150 mg daily MD) in non-diabetic obese [body mass index (BMI) ≥30 kg/m2] patients, with coronary artery disease (CAD) on aspirin therapy. PD assessments (baseline, 2 hours post-LD and 6 ± 2 days after MD) were conducted using four platelet function assays, and the platelet reactivity index (PRI) assessed by VASP was used for sample size estimation. A total of 42 patients with a BMI of 36.42 ± 5.6 kg/m2 completed the study. There were no differences in baseline PD measures between groups. At 2 hours post-LD, prasugrel was associated with lower PRI compared with clopidogrel (24.3 ± 5.5 vs 58.7 ± 5.7, p≤0.001), with consistent findings for all assays. At one-week, PRI values on prasugrel MD were lower than clopidogrel MD without reaching statistical significance (34.7 ± 5.8 vs 42.9 ± 5.8, p=0.32), with consistent findings for all assays. Accordingly, rates of high on-treatment platelet reactivity were markedly reduced after prasugrel LD, but not after MD. In conclusion, in non-diabetic obese patients with CAD, standard prasugrel dosing achieved more potent PD effects than high-dose clopidogrel in the acute phase of treatment, but this was not sustained during maintenance phase treatment. Whether an intensified prasugrel regimen is required in obese patients warrants investigation.

Antiplatelet Agents for the Treatment and Prevention of Coronary Atherothrombosis

Antiplatelet drugs provide first-line antithrombotic therapy for the management of acute ischemic syndromes (both coronary and cerebrovascular) and for the prevention of their recurrence. Their role in the primary prevention of atherothrombosis remains controversial because of the uncertain balance of the potential benefits and risks when combined with other preventive strategies. The aim of this consensus document is to review the evidence for the efficacy and safety of antiplatelet drugs, and to provide practicing cardiologists with an updated instrument to guide their choice of the most appropriate antiplatelet strategy for the individual patient presenting with different clinical manifestations of coronary atherothrombosis, in light of comorbidities and/or interventional procedures.

Low body weight and clinical outcomes in acute coronary syndrome patients: results of the ACHILLES Registry

BACKGROUND

Being overweight increases the risk of cardiovascular diseases and mortality. However, among high-body-weight patients with established acute coronary syndrome (ACS) this evidence is not clear. In this scenario, a low body weight (LBW) has been proposed to confer higher prognostic risk and higher bleeding risk with new P2Y₁₂ inhibitors.

AIMS

We aimed to examine differences in mortality, catheterizations/revascularizations, antiplatelet therapy and ischemic/bleeding adverse events between ACS patients with LBW.

METHODS

This is a multicenter registry involving 1576 consecutive ACS patients (ST-elevation myocardial infarction (STEMI), non-STEMI, or unstable angina) from three tertiary institutions. Patients were divided into two groups: LBW (weight < 60 kg, n = 176) and non-LBW (weight ⩾ 60 kg, n = 1400). During 12 months follow-up, we recorded management (catheterizations/revascularizations), antiplatelet therapy, major adverse cardiovascular events (MACEs), bleeding events (BARC classification), and mortality.

RESULTS

Catheterizations (86.4% vs. 93.4%; p = 0.001) and revascularizations (64.8% vs. 76.1%; p = 0.001) were significantly lower in the LBW group. At discharge, prescription of new P2Y₁₂ inhibitors was also lower in LBW patients (24.4% vs. 37.8%; p = 0.001). After 12-month follow-up, the incidence of MACE (HR 1.61 (95% CI 1.03-2.50]; p = 0.038) and mortality (HR 2.18 (95% CI 1.33-3.58); p = 0.002) was higher in LBW patients compared with non-LBW. In contrast, there were no significant differences for bleeding events.

CONCLUSIONS

LBW in ACS patients was associated with higher incidence of MACE and mortality. In this group of patients less catheterizations and coronary revascularizations were performed. Despite there being no differences in bleeding rates, new P2Y₁₂ inhibitors were less prescribed in LBW patients.

The Rationale for and Clinical Pharmacology of Prasugrel 5 mg

Prasugrel is a third-generation thienopyridine platelet P2Y₁₂ adenosine diphosphate (ADP) receptor antagonist administered with aspirin for the treatment of patients with acute coronary syndrome (ACS) with planned percutaneous coronary intervention. Prasugrel is administered periprocedurally at an oral loading dose of 60 mg followed by daily maintenance doses (MDs) of 10 mg for most patients and 5 mg for patients weighing <60 kg or aged ≥75 years. Data from a prasugrel phase III study, TRITON-TIMI 38, suggested that a lower MD might be more suitable for patients weighing <60 kg or aged ≥75 years; subsequent pharmacokinetic and pharmacodynamic studies have indicated that prasugrel 5 mg reduced platelet reactivity in these populations to an extent similar to that of prasugrel 10 mg in heavier or younger patients. Clinical experience with prasugrel 5 mg is limited, and additional studies are needed to verify the clinical efficacy and safety of this dose in these challenging populations.

Prasugrel hydrochloride for the treatment of acute coronary syndrome patients

INTRODUCTION

Dual antiplatelet therapy (DAPT) with aspirin combined with either a thienopyridine (clopidogrel or prasugrel) or acyclopentyl-triazolo-pyrimidine (ticagrelor) plays a vital role in the management of acute coronary syndrome (ACS) especially in those undergoing percutaneous coronary intervention (PCI) but even those being managed medically. Observational studies and some formal studies have shown patients on the standard dual antiplatelet regimen (clopidogrel and aspirin) continue to have further ischemic events and can suffer stent thrombosis. It has been demonstrated that clopidogrel is associated with a delayed onset of action with a considerable inter-individual variation to treatment thus making it difficult to achieve an optimal level of platelet inhibition. Areas covered: This article will review the current evidence that is available regarding the effectiveness and safety of prasugrel in ACS patients undergoing percutaneous coronary intervention (PCI). Expert commentary: Prasugrel is an oral third-generation inhibitor of platelet activation and aggregation. Laboratory studies and early phase clinical trials show prasugrel has a faster onset of action, is more potent and has reduced inter-patient response variability compared to clopidogrel. The published studies so far demonstrated that prasugrel when compared to clopidogrel also shows a higher degree of effectiveness in the prevention of platelet-initiated thrombotic events in patients with ACS undergoing PCI, however these benefits are offset somewhat by an increased bleeding risk.

Bleeding events and maintenance dose of prasugrel: BLESS pilot study

Objective

To evaluate changes in residual platelet reactivity (RPR) over time, and bleeding and ischaemic events rate using 5 vs 10 mg maintenance dose (MD) regimens of prasugrel 1 month after acute coronary syndrome (ACS).

Background

The optimal level of RPR with prasugrel may change over time after an ACS.

Methods

After 60 mg loading dose of prasugrel (T0) followed by 10 mg/day for 1 month, patients were randomised to receive prasugrel 10 mg/day (n=95, group A) or 5 mg/day MD (n=98, group B) up to 1 year. RPR was assessed at T0, 37 (T1) and 180 days (T2). The primary end point was Bleeding Academic Research Consortium (BARC) bleeding events ≥2 between 1 and 12 months, and the secondary composite end point was cardiac death, myocardial infarction, stroke and definite/probable stent thrombosis.

Results

From T0 to T1, RPR significantly increased in both groups A and B and the increase was higher for group B (δ ADP 10 µmol: 13.8%±14.7% vs 23.5%±19.2%, p=0.001). At T2 a lower rate of high RPR patients were found in group A (2.6% vs13.3%; p=0.014). The BARC type ≥2 bleeding occurred in 12.6% of group A versus 4.1% of group B (OR 0.29, 95% CI 0.09 to 0.94) and secondary end point in 2.1% vs 1.0% (p=0.542), respectively, without stent thrombosis.

Conclusions

RPR increases shifting from 60 mg loading dose to 10 mg/day prasugrel MD with a further increase of RPR reducing prasugrel MD to 5 mg 1 month after ACS. Clinical value of these pharmacodynamic findings should be proved in larger clinical trials.

Trial registration number

NCT01790854.

Platelet Aggregation Inhibitory Effects and Pharmacokinetics of Prasugrel Used in Combination With Aspirin in Healthy Japanese Subjects

We evaluated the pharmacokinetics and pharmacodynamics of prasugrel used in combination with aspirin in healthy Japanese subjects. All subjects received aspirin 100 mg/day. Subsequently, in the single‐administration study, 23 subjects also received prasugrel 20 or 30 mg, and in the multiple‐administration study, 20 subjects received a loading dose of prasugrel 20 or 30 mg on day 1, followed by a maintenance dose of prasugrel 5 or 7.5 mg/day, respectively, on days 2–5. In both studies, the plasma concentration of the active metabolite of prasugrel, R‐138727, reached a maximum 0.5 hours after administration and rapidly decreased within 4 hours. In the single‐administration study, the inhibitory effect on adenosine diphosphate–induced platelet aggregation was significantly higher in the prasugrel 20‐ and 30‐mg groups than in the placebo group at all times (1–144 hours) after administration. In the multiple‐administration study, a similar antiplatelet effect was found after both the loading dose and the maintenance dose and was maintained for 3–6 days after the last administration. There were study drug‐related adverse events; however, all were mild, and none was clinically significant.

Impact of timing from blood sampling to pharmacodynamic assessment on measures of platelet reactivity in patients treated with P2Y12 receptor inhibitors

Several platelet function tests (PFT) are available to assess the pharmacodynamic (PD) effects of P2Y₁₂ inhibitors. However, there are technical variances between PFT, and P2Y₁₂ inhibitors differ in pharmacological properties. Manufactures of PFT recommend a time-frame within which assessments needs to be executed. However, if the timing from blood sampling to processing affects PD results is unknown. We conducted a prospective study assessing the impact of timing from blood sampling to processing on PD measures using three different PFT. We studied 60 aspirin-treated patients with coronary artery disease (CAD) on maintenance P2Y₁₂ inhibiting therapy [clopidogrel 75 mg/day (n=20), prasugrel 10 mg/day (n=20) and ticagrelor 90 mg bid (n=20)]. PD assessments (trough levels) were performed by VerifyNow P2Y12 (VN), light transmittance aggregometry (LTA) and vasodilator-stimulated phosphoprotein (VASP) at 30 minutes, 2 and 4 hours post-sampling; VASP was also performed at 24 hours. P2Y₁₂ reaction units (PRU) by VN significantly decreased over time with all P2Y₁₂ inhibitors (clopidogrel p<0.001; prasugrel p=0.016; ticagrelor p<0.001). PRU at 30 minutes and 2 hours were similar, but decreased at 4 hours. LTA showed consistent findings with VN. Conversely, PD measures as assessed by VASP were stable over time (p>0.1 for all P2Y₁₂ inhibitors). In conclusion, in CAD patients on maintenance therapy with P2Y₁₂ inhibitors, timing from blood sampling to processing significantly influences PD measures as assessed by VN and LTA, but not by VASP.

Prasugrel Use in Real Life: A Report From the Outpatient Setting in France

The objective of this study was to provide descriptive statistics on patterns of prasugrel usage in the outpatient setting in France. This retrospective study was conducted to describe treatment patterns for prasugrel in the outpatient setting in France using the Intercontinental Marketing Services (IMS) Disease Analyzer database, which collates electronic medical records updated by a nationally representative database of 1200 French general practitioners (GPs). Anonymous data were collected prospectively at each follow-up visit. The study population consisted of patients with ≥1 prescription for prasugrel in the outpatient setting from its launch date to 3 years post-launch. Patients were followed up from the date of the first prescription for prasugrel recorded in the database until they died, changed GP, or reached the end of the study, whichever came first. In France, the IMS Disease Analyzer included 1052 patients receiving ≥1 prescription of prasugrel from January 2010 until October 2012. Eighty-five percent of the population was male. The mean age was 58 years; 94.3% were age <75 years, and 95.0% weighed ≥60 kg. Of the total, 99.8% of patients were prescribed a daily maintenance dose of 10 mg, and 0.2% had a history of transient ischemic attack/stroke. Concomitant medications were antiplatelet agents (100%; aspirin, 93.7%), lipid-lowering agents (90.1%), β-blockers (83.7%), angiotensin-converting enzyme inhibitors (62.2%), and anti-ulcer medications (55.1%). The results reflect good usage of prasugrel by French GPs in the outpatient setting, with excellent implementation of the Prasugrel European Summary Product Characteristics.

Concomitant proton-pump inhibitor use, platelet activity, and clinical outcomes in patients with acute coronary syndromes treated with prasugrel versus clopidogrel and managed without revascularization: insights from the Targeted Platelet Inhibition to Clarify the Optimal Strategy to Medically Manage Acute Coronary Syndromes trial

Concomitant use of proton-pump inhibitors (PPIs) has been implicated in diminished antiplatelet response to clopidogrel and an increased risk of ischemic events, but primarily among patients undergoing percutaneous coronary intervention. We sought to examine the potential influence of interactions between PPIs and clopidogrel versus prasugrel on platelet reactivity and clinical outcomes after acute coronary syndromes (ACS) in patients managed medically without revascularization.

METHODS

This analysis from the TRILOGY ACS trial focused upon the 7,243 ACS patients aged <75 years who were managed without revascularization, randomized to clopidogrel or prasugrel, and followed for a median of 17 months. Proton-pump inhibitor type and use were assessed at each study visit, and 2,049 of the patients in this cohort underwent serial platelet reactivity assessments.

RESULTS

Proton-pump inhibitor use (23%) was similar between the clopidogrel and prasugrel groups at baseline and throughout the study. Median on-treatment platelet reactivity values were consistently lower with prasugrel versus clopidogrel irrespective of PPI use. For the primary end point (composite of cardiovascular death, myocardial infarction [MI], or stroke), PPI use modified the unadjusted treatment effect of prasugrel versus clopidogrel (interaction P = .02). After adjusting for differences in baseline characteristics, this treatment effect modification was attenuated for the composite end point (interaction P = .06) but was significant for the MI component end point (interaction P = .01). Similarly, among patients on a PPI, the frequency of MI was significantly lower with prasugrel versus clopidogrel (hazard ratio = 0.61; 95% CI 0.42-0.88). These findings were similar by PPI type (omeprazole and pantoprazole).

CONCLUSIONS

Among ACS patients managed without revascularization, use of PPIs did not result in a differential antiplatelet response between prasugrel versus clopidogrel but was associated with a lower incidence of MI with prasugrel. These hypothesis-generating findings suggest that factors besides platelet reactivity may underlie the differential risk of MI observed by treatment assignment with PPI use.

New approaches to inhibiting platelets and coagulation

Ischemic heart disease and stroke are major causes of death and morbidity worldwide. Coronary and cerebrovascular events are a consequence of thrombus formation caused by atherosclerotic plaque rupture or embolism, both of which result from platelet activation and aggregation and thrombin-mediated fibrin generation via the coagulation cascade. Current and emerging antiplatelet and anticoagulant agents are evolving rapidly. The use of aspirin for primary prevention continues to be controversial, as are the doses appropriate for secondary prevention. Development of new oral and intravenous adenosine diphosphate P2Y12 inhibitors and novel antiplatelet agents continues to transform the landscape of antiplatelet therapy. Oral anticoagulation has advanced with the use of direct thrombin and factor Xa inhibitors that do not require therapeutic monitoring. In this review, we discuss the pharmacology and growing clinical evidence for traditional and new antiplatelet and anticoagulant therapies.

Antiplatelet Therapy in Hemodialysis Patients Undergoing Percutaneous Coronary Interventions

Context:

Coronary artery disease is highly prevalent among patients with end stage renal disease/hemodialysis (ESRD/HD) and coronary percutaneous interventions (PCI) has been increased by nearly 50% over the past decade. After PCI with stent placement, guidelines recommend dual antiplatelet therapy (DAPT), but no specifically tailored pharmacotherapy approach is outlined for this frail population, mostly excluded from large randomized clinical trials (RCTs).

Evidence Acquisition:

We reviewed current evidences on the use of antiplatelet therapy in patients with ESRD/HD undergoing PCI, focusing on the efficacy and safety of specific agents and their indications for detailed clinical settings.

Results:

Clinical setting in HD patients is the principal determinant of the type, onset, combination and duration of the DAPT. However, irrespective clinical setting, in addition to aspirin, clopidogrel is currently the most used antiplatelet agent even if no information derived from RCTs are available in ESRD. Due to the large experience acquired in routine clinical practice, the awareness of safety is higher for clopidogrel than newer antiplatelet agents. Because of lack of data, the use of prasugrel and ticagrelor is actually not recommended. However, in case of high ischemic and acceptable bleeding risk, they may be selectively used in ESRD/HD.

Conclusions:

This investigation might contribute to delineate the best treatment options for this high risk population.

Pharmacology of antithrombotic drugs: an assessment of oral antiplatelet and anticoagulant treatments

Antithrombotic drugs, which include antiplatelet and anticoagulant therapies, prevent and treat many cardiovascular disorders and, as such, are some of the most commonly prescribed drugs worldwide. The first drugs designed to inhibit platelets or coagulation factors, such as the antiplatelet clopidogrel and the anticoagulant warfarin, significantly reduced the risk of thrombotic events at the cost of increased bleeding in patients. However, both clopidogrel and warfarin have some pharmacological limitations including interpatient variability in antithrombotic effects in part due to the metabolism, interactions (eg, drug, environment, and genetic), or targets of the drugs. Increased knowledge of the pharmacology of antithrombotic drugs and the mechanisms underlying thrombosis has led to the development of newer drugs with faster onset of action, fewer interactions, and less interpatient variability in their antithrombotic effects than previous antithrombotic drugs. Treatment options now include the next-generation antiplatelet drugs prasugrel and ticagrelor, and, in terms of anticoagulants, inhibitors that directly target factor IIa (dabigatran) or Xa (rivaroxaban, apixaban, edoxaban) are available. In this Series paper we review the pharmacological properties of these most commonly used oral antithrombotic drugs, and explore the development of antiplatelet and anticoagulant therapies.

P2Y12 antagonists in non-ST-segment elevation acute coronary syndromes: latest evidence and optimal use

Dual antiplatelet therapy (DAPT), which includes the combination of aspirin and a P2Y12 platelet receptor inhibitor, is a well-established antiplatelet regimen in the treatment of patients with non-ST-segment elevation acute coronary syndrome (NSTE-ACS). Three P2Y12 inhibitor options (clopidogrel, prasugrel and ticagrelor) are currently available, all having different efficacy and safety profiles along with contrasting contraindications, special warnings and precautions for use. This review compares and contrasts the unique P2Y12 antagonists in the NSTE-ACS setting, covering the latest evidence and their optimal use.

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

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 noncompartmental methods. Light transmission aggregometry (LTA) (maximum platelet aggregation and inhibition of platelet aggregation to 20 μM adenosine diphosphate (ADP), and residual platelet aggregation to 5 μM ADP), VerifyNow(®) 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.