Pharmacodynamics, pharmacokinetics, and safety of the oral reversible P2Y12 antagonist AZD6140 with aspirin in patients with atherosclerosis: a double-blind comparison to clopidogrel with aspirin

Systematic review with meta-analysis: the risk of gastrointestinal bleeding in patients taking third-generation P2Y12 inhibitors compared with clopidogrel

BACKGROUND

Ticagrelor and prasugrel are third-generation oral P2Y₁₂ receptor antagonists with rapid onset and pronounced platelet inhibition. However, higher overall bleeding rates have been reported for these agents when compared with clopidogrel.

AIM

To compare the risk of gastrointestinal bleeding (GIB) among users of third-generation P2Y₁₂ inhibitors with clopidogrel.

METHODS

We systematically searched for published randomised controlled trials of ticagrelor or prasugrel versus clopidogrel until September 2018. The primary outcome was the risk of GIB among users of third-generation P2Y₁₂ inhibitors when compared to clopidogrel, expressed as risk ratio (RR) and 95% confidence interval (CI). The rates of non-coronary artery bypass graft (CABG) major bleeding, life-threatening bleeding, fatal bleeding, and intracranial bleeding were analysed as secondary outcomes.

RESULTS

Forty-one studies were included in the analysis of non-CABG major bleeding, of which 12 were included in the analysis of GIB including 58 678 patients. Third-generation P2Y₁₂ inhibitors were associated with higher risk of GIB as compared with clopidogrel (RR 1.28, 95% CI 1.13-1.46). The findings were consistent for upper (RR 1.32, 95% CI 1.05-1.67) and unspecified GIB (RR 1.25, 95% CI 1.01-1.53), but not lower GIB (RR 1.25, 95% CI 0.95-1.65). Subgroup analysis showed higher GIB risk in prasugrel studies (RR 1.40, 95% CI 1.10-1.77) than in ticagrelor studies (RR 1.15, 95% CI 0.94-1.39). Third-generation P2Y₁₂ inhibitors also increased the risk of non-CABG major bleeding (RR 1.18, 95% CI 1.08-1.28).

CONCLUSION

Third-generation P2Y₁₂ inhibitors were associated with increased risk of GIB and non-CABG major bleeding when compared with clopidogrel.

Clinical safety profile of ticagrelor compared to clopidogrel in 1208 patients: Real world evidence

Introduction

Dual antiplatelet treatment is recommended by current clinical practice guidelines for patients undergoing PCI. The PLATO trial showed superiority of ticagrelor to clopidogrel in reducing the rate of death from vascular causes, myocardial infarction and stroke without increase in the rate of overall major bleeding in ACS patients. However, real world evidence in Indian patients is limited. The objective of this study is to compare safety profile of ticagrelor with clopidogrel in real world settings.

Methodology

In this single centered retrospective observational study, a total of 1208 serial patient records undergoing PCI (ACS and stable angina patients as well) treated with Ticagrelor or Clopidogrel were collected and analyzed to look into in hospital outcomes. We excluded the patient’s data that were incomplete.

Results

In total of 1208 patients, 604 patients received ticagrelor and similarly 604 patient received clopidogrel. No significant differences in the rates of major life threatening bleeding and any major bleeding were observed between ticagrelor and clopidogrel group (0.2% (n = 1) vs. 0.7% (n = 4), p = 0.18 and 2.8% (n = 17) vs. 3% (n = 18), p = 0.86 respectively). There was increase in minor bleeding rate with ticagrelor compared to clopidogrel (21.4% & 13.6%, p = 0.00).

Conclusion

In the real world settings, patients undergoing PCI treated with ticagrelor showed similar safety profile compared to clopidogrel but with increase in minor bleeding rate. The observed results were in alignment with PLATO clinical trial.

A dose-ranging study of ticagrelor in children aged 3-17 years with sickle cell disease: A 2-part phase 2 study

Antiplatelet treatment is a potential therapeutic approach for sickle cell disease (SCD). Ticagrelor inhibits platelet aggregation and is approved for adults with acute coronary syndrome and following myocardial infarction. HESTIA1 (NCT02214121) was a 2-part, phase 2 dose-finding study generating ticagrelor exposure, platelet inhibition, and safety data in children with SCD (3-17 years). In part A (n = 45), patients received 2 ticagrelor single doses, 0.125-2.25 mg/kg (washout ≥7 days), then 7 days of twice-daily (bid) dosing with 0.125, 0.563, or 0.75 mg/kg. In the 4-week blinded Part B extension (optional), patients received ticagrelor (0.125, 0.563, or 0.75 mg/kg bid; n = 16) or placebo (n = 7). Platelet reactivity decreased from baseline to 2 hours postdosing, and returned to near baseline after 6 hours postdosing. Dose-dependent platelet inhibition was seen with ticagrelor; mean relative P2Y12 reaction unit inhibition 2 hours after a single dose ranged from 6% (0.125 mg/kg) to 73% (2.25 mg/kg). Ticagrelor plasma exposure increased approximately dose proportionally. No patients experienced a hemorrhagic event during treatment. No differences were seen between groups in pain ratings and analgesic use during Part B. Ticagrelor was well tolerated with no safety concerns, no discontinuations due to adverse events (AEs), and reported AEs were mainly due to SCD. In conclusion, a dose-exposure-response relationship for ticagrelor was demonstrated in children with SCD for the first time. These data are important for future pediatric studies of the efficacy and safety of ticagrelor in SCD.

Compared efficacy of clopidogrel and ticagrelor in treating acute coronary syndrome: a meta-analysis

Background & Aims

Ticagrelor has been acknowledged as a new oral antagonist of P2Y12-adenosine diphosphate receptor, as a strategy with more rapid onset as well as more significant platelet inhibition function in acute coronary syndrome (ACS) patients. The clinical benefit of ticagrelor compared with clopidogrel remains controversial. The current meta-analysis was conducted to better evaluate the role of ticagrelor in comparison of clopidogrel in treating ACS patients.

Methods

The publications involving the safety as well as the efficacy of clopidogrel versus ticagrelor were screened and identified updated to June 2018. After rigorous review, eligible randomized controlled trials (RCTs) were extracted and propensity score matching (PSM) analysis was conducted. To analyze the summary odds ratios (ORs) of the endpoints of interest, we applied Meta-analysis Revman 5.3 software.

Results

There were a total of 10 studies that met our inclusion criteria, of which the risk of bleeding rate (P = 0.43), MI (P = 0.14), and stroke (P = 0.70) had no association with significant differences between patients receiving ticagrelor or clopidogrel. Nonetheless, higher rate of dyspnea was observed in ticagrelor group (OR = 1.87, 95% CI: 1.70–2.05, P<0.00001 = .

Conclusions

Our present findings suggest similar efficacy and safety profiles for clopidogrel and ticagrelor Ticagrelor should be considered as a valuable option to reduce the risk of bleeding, MI and stroke, whereas potentially increases the incidence of dyspnea. Given the metabolic process, ticagrelor may be a valid and even more potent antiplatelet drug than clopidogrel, as an alternative strategy in treating patients with clopidogrel intolerance or resistance.

Effect of P2Y12 inhibitors on thrombus stability and endogenous fibrinolysis

Although used routinely to reduce thrombotic events in patients with coronary disease, the effects of P2Y₁₂ inhibitors on thrombus stability and endogenous fibrinolysis are largely unknown. Blood taken from patients pre- and post-aspirin (n = 20) and on aspirin alone and on dual antiplatelet therapy comprising aspirin plus clopidogrel (n = 20), ticagrelor (n = 20) or cangrelor (n = 20), was tested using the Global Thrombosis Test. The number of "rebleeds" or drops (D) after early platelet-rich thrombus formation (occlusion time, OT), and before final lasting occlusion, was used as an inverse measure of thrombus stability. Whilst clopidogrel had no effect, ticagrelor and cangrelor both increased D significantly, reflecting increased thrombus instability [D pre- and post-clopidogrel 4.3 ± 1.6 vs. 4.5 ± 1.4, p = 0.833; pre- and post-ticagrelor 4.1 ± 2.4 vs. 6.8 ± 5.1, p = 0.048; pre- and post-cangrelor 3.6 ± 2.0 vs. 7.9 ± 8.9, p = 0.046]. Platelet reactivity was reduced by all P2Y₁₂ inhibitors, demonstrated by OT prolongation (clopidogrel 378 ± 87 s vs. 491 ± 93 s, p < 0.001; ticagrelor 416 ± 122 s vs. 549 ± 121 s, p < 0.001; cangrelor 381 ± 146 s vs. 613 ± 210 s, p < 0.001). The magnitude of OT prolongation compared to baseline (ΔOT) was significantly greater for cangrelor compared to clopidogrel and ticagrelor. Cangrelor was the only agent to enhance fibrinolysis (lysis time pre- and post-cangrelor 1622[1240-2048]s vs. 1388[960-1634]s, p = 0.005). We demonstrate the ability to assess the effect of pharmacotherapy on thrombus stability in vitro and show that P2Y₁₂ inhibitors potentiate thrombus instability at high shear. Cangrelor, and to a lesser extent ticagrelor, de-stabilised thrombus formation and cangrelor also enhanced fibrinolysis. Potentiation of thrombus instability could become a new pharmacological target, that may be particularly important in acute coronary syndromes.

A novel composition of ticagrelor by solid dispersion technique for increasing solubility and intestinal permeability

The aim of this study is to improve the bioavailability of ticagrelor, BCS class 4 drug, using solid dispersion technique, and to evaluate the potential of ticagrelor loaded-solid dispersion, as a new formulation. The solid dispersion formulation was prepared via solvent evaporation method using ethanol. TPGS and Neusilin® US2 selected via screening studies were used for preparing formulation. The results of scanning electron microscopy, differential scanning calorimetry and powder X-ray diffraction showed that the crystallinity of the ticagrelor was completely transformed to an amorphous form and maintained in the solid dispersion formulation. The released amount of the optimized solid dispersion significantly increased by 2.2- and 34-fold in comparison with physical mixture (Ticagrelor:TPGS:Neusilin® US2 = 1:2:2, w/w/w) and commercial product (Brilinta®) in distilled water at 90 min, respectively. The absorptive permeability was improved (1.4-fold) and the efflux ratio was decreased (0.45-fold) by formulation containing TPGS acting as a P-gp inhibitor compared to pure drug. The solid dispersion formulation improved the peak plasma concentration (C_max) and relative bioavailability compared to that of pure drug as 238.09 ± 25.96% and 219.78 ± 36.33%, respectively, after oral administration in rats. Thus, we successfully prepared the solid dispersion formulation for enhancing oral bioavailability of ticagrelor, and then this formulation would be recommended as a practical oral pharmaceutical product.

Antiplatelet effects of ticagrelor versus clopidogrel after coronary artery bypass graft surgery: A single-center randomized controlled trial

OBJECTIVE

The study objective was to compare the onset of platelet inhibition (inhibition of platelet aggregation) between ticagrelor 90 mg twice per day and clopidogrel 75 mg once per day in patients receiving coronary artery bypass grafting.

METHODS

In a single-center, randomized, open-label study, 140 patients receiving coronary artery bypass grafting were randomly assigned to the aspirin + ticagrelor group or the aspirin + clopidogrel group in a 1:1 ratio. Participants in the aspirin + ticagrelor group took aspirin 100 mg once per day and ticagrelor 90 mg twice per day. Participants in the aspirin + clopidogrel group took aspirin 100 mg once per day and clopidogrel 75 mg once per day. Platelet function was determined before study treatment (0 hours); at 2 hours, 8 hours, 24 hours, and 72 hours after medication; and during follow-up at 30 days after surgery.

RESULTS

Inhibition of platelet aggregation at 2 hours after the first drug administration was greater for the aspirin + ticagrelor group than for the aspirin + clopidogrel group (34.2% [interquartile range, 9.1-66.0] vs 5.3% [interquartile range, -14.3-22.0], P < .001) and at all times in the study period (P < .001). More patients reached inhibition of platelet aggregation maximum within 24 hours in the aspirin + ticagrelor group than in the aspirin + clopidogrel group (52.9% vs 27.5%, P = .006). The average inhibition of platelet aggregation maximum from 2 to 24 hours was still greater in the aspirin + ticagrelor group than in the aspirin + clopidogrel group (72.3% ± 15.4% vs 49.2% ± 46.8%, P < .001). There were no differences in terms of bleeding or major adverse cardiac events between the 2 groups.

CONCLUSIONS

In patients receiving coronary artery bypass grafting, the onset of action was faster and the peak inhibition of platelet aggregation was higher with ticagrelor than with clopidogrel.

Oral antiplatelet agents in cardiovascular disease

Antiplatelet agents significantly reduce mortality and morbidity in ischemic heart disease, cerebrovascular disease and peripheral artery disease (PAD), and are therefore part of guideline-driven daily medical treatment in these patients. Due to its beneficial effects in the secondary prevention of atherothrombotic events, aspirin remains the most frequently prescribed antiplatelet agent in cardiovascular disease. In patients with acute coronary syndromes (ACS) and in those undergoing angioplasty with stent implantation dual antiplatelet therapy with aspirin and an adenosine diphosphate (ADP) receptor antagonist is indicated. The development of the newer ADP P2Y₁₂ inhibitors prasugrel and ticagrelor has further improved prognosis in ACS patients compared to clopidogrel. Moreover, vorapaxar allows the inhibition of platelet activation by thrombin via protease-activated receptor-1 and has been approved for the use in patients with PAD and in those with a history of myocardial infarction. This review article summarizes the current evidence on oral antiplatelet agents in cardiovascular disease. Keywords: Aspirin, clopidogrel, prasugrel, ticagrelor, vorapaxar, cardiovascular disease.

Anti-platelet treatments in cancer: Basic and clinical research

Over the past few decades the central role that platelets play in cancer development and progression, and especially in metastasis, has been elucidated. The molecular mechanisms responsible for initiating and mediating tumor cell-induced platelet aggregation and secretion have been largely unravelled. Considerable mechanistic insight into how platelets contribute to tumor angiogenesis, immunoevasion and cancer cell invasion have been clarified and, consequently, platelets have been identified as potential new drug targets for cancer therapy. This article gives an overview of the platelet-targeted pharmacologic approaches that have been attempted in the prevention of cancer development, progression and metastasis, including the application of antiplatelet drugs currently used for cardiovascular disease and of new and novel strategies.

Choosing between ticagrelor and clopidogrel following percutaneous coronary intervention: A systematic review and Meta-Analysis (2007-2017)

BACKGROUND

Limitations have been observed with the use of clopidogrel following percutaneous coronary intervention (PCI) indicating the urgent need of a more potent anti-platelet agent. We aimed to compare the efficacy and safety of ticagrelor versus clopidogrel following PCI.

METHODS

Online databases were searched for relevant studies (published between the years 2007 and 2017) comparing ticagrelor versus clopidogrel following coronary stenting. Primary outcomes assessed efficacy whereas secondary outcomes assessed safety. Odds ratios (OR) with 95% confidence intervals (CIs) based on a random effect model were calculated and the analysis was carried out by the RevMan 5.3 software.

RESULTS

A total number of 25,632 patients with acute coronary syndrome (ACS) [12,992 patients with ST segment elevation myocardial infarction (STEMI) and 14,215 patients with non-ST segment elevation myocardial infarction (NSTEMI)] were included in this analysis, of whom 23,714 patients were revascularized by PCI. Results of this analysis did not show any significant difference in all-cause mortality, major adverse cardiac events (MACEs), myocardial infarction, stroke and stent thrombosis observed between ticagrelor and clopidogrel with (OR: 0.83, 95% CI: 0.67-1.03; P = .09), (OR: 0.64, 95% CI: 0.41-1.01; P = .06), (OR: 0.77, 95% CI: 0.57-1.03; P = .08), (OR: 0.85, 95% CI: 0.57-1.26; P = .42) and (OR: 0.70, 95% CI: 0.47-1.05; P =.09).However, ticagrelor was associated with a significantly higher minor and major bleeding with (OR: 1.57, 95% CI: 1.30-1.89; P = .00001) and (OR: 1.52, 95% CI: 1.01-2.29; P = 0.04) respectively. Dyspnea was also significantly higher in the ticagrelor group (OR: 2.64, 95% CI: 1.87-3.72; P = .00001).

CONCLUSION

Ticagrelor and clopidogrel were comparable in terms of efficacy in these patients with ACS. However, the safety outcomes of ticagrelor should further be investigated.

Preparation and Characterization of Novel Pharmaceutical Co-Crystals: Ticagrelor with Nicotinamide

Two new co-crystals, Ticagrelor with Nicotinamide, have been prepared with improved solubility. Because Ticalegor has a poor solubility and dissolution rate, a novel co-crystallization method with structurally homogenous crystalline material, an active pharmaceutical ingredient (API), and co-former indefinite stoichiometric amount has been made to improve Ticagrelor’s solubility. The co-crystal of Ticagrelor (TICA) with Nicotinamide (NCA) was prepared in ratio (1:1) and confirmed by FTIR, DSC, and XRD characterization. Furthermore, the single crystal structure of TICA-NCA hydrate was analyzed. The solubility of co-crystals was investigated in pH 2 acidic medium, which was a significant improvement as compared to the solubility of a free drug. The in vitro dissolution rate of co-crystal was larger than that of the commercial product.

CYP3A4*22 Impairs the Elimination of Ticagrelor, But Has No Significant Effect on the Bioactivation of Clopidogrel or Prasugrel

CYP3A enzymes participate in the elimination of ticagrelor and the bioactivation of clopidogrel and prasugrel. We studied the effects of functional CYP3A genetic variants (CYP3A4*22; rs35599367 and CYP3A5*3; rs776746) on the pharmacokinetics and pharmacodynamics of ticagrelor, clopidogrel, and prasugrel. Six healthy volunteers with the CYP3A4*1/*22 and CYP3A5*3/*3 genotype (CYP3A4*22 carriers), eight with the CYP3A4*1/*1 and CYP3A5*1/*3 genotype (CYP3A5 expressors), and 11-13 with the CYP3A4*1/*1 and CYP3A5*3/*3 genotypes (controls) ingested single doses of ticagrelor, clopidogrel, and prasugrel on separate occasions. Ticagrelor area under the plasma concentration-time curve (AUC) was 89% (P = 0.004) higher in CYP3A4*22 carriers than in controls. CYP3A4*22 carriers also showed more pronounced platelet inhibition at 24 hours after ticagrelor ingestion than the controls (43% vs. 21%; P = 0.029). The CYP3A5 genotype did not affect ticagrelor pharmacokinetics. Neither CYP3A5 nor CYP3A4 genotypes significantly affected prasugrel or clopidogrel. In conclusion, the CYP3A4*22 allele markedly impairs ticagrelor elimination enhancing its antiplatelet effect.

Real-world incidence of patient-reported dyspnoea with ticagrelor

Dyspnoea, a common and multifactorial symptom in patients with acute coronary syndrome, has been associated with lower quality of life and hospital readmission. Prescriber preference for antiplatelet therapy, the standard of care in this patient group, is shifting to ticagrelor due to mortality benefits demonstrated in trials compared with clopidogrel. In these trials, dyspnoea was more commonly reported in patients prescribed ticagrelor but the aetiology is still debated. An observational cohort study was conducted to quantify the rates and severity of dyspnoea reported in patients with acute coronary syndrome and newly prescribed ticagrelor compared with those prescribed clopidogrel. Dyspnoea was more commonly reported in patients prescribed ticagrelor at each follow up post-discharge (p = 0.016). Rates were higher than previously reported in clinical trials. In some patients, dyspnoea necessitated drug therapy change and was associated with readmission to hospital (p = 0.046). As ticagrelor is widely prescribed as a first-line antiplatelet agent for a range of patients with acute coronary syndrome, the incidence of dyspnoea in a generalized patient cohort may result in higher rates of drug discontinuation. This in turn could lead to higher rates of rehospitalisation and potential treatment failure than that reported from the controlled setting of a clinical trial.

Metabolism of ticagrelor in patients with acute coronary syndromes

Ticagrelor is a state-of-the-art antiplatelet agent used for the treatment of patients with acute coronary syndromes (ACS). Unlike remaining oral P2Y12 receptor inhibitors ticagrelor does not require metabolic activation to exert its antiplatelet action. Still, ticagrelor is extensively metabolized by hepatic CYP3A enzymes, and AR-C124910XX is its only active metabolite. A post hoc analysis of patient-level (n = 117) pharmacokinetic data pooled from two prospective studies was performed to identify clinical characteristics affecting the degree of AR-C124910XX formation during the first six hours after 180 mg ticagrelor loading dose in the setting of ACS. Both linear and multiple regression analyses indicated that ACS patients presenting with ST-elevation myocardial infarction or suffering from diabetes mellitus are more likely to have decreased rate of ticagrelor metabolism during the acute phase of ACS. Administration of morphine during ACS was found to negatively influence transformation of ticagrelor into AR-C124910XX when assessed with linear regression analysis, but not with multiple regression analysis. On the other hand, smoking appears to increase the degree of ticagrelor transformation in ACS patients. Mechanisms underlying our findings and their clinical significance warrant further research.

Ticagrelor versus clopidogrel in patients with symptomatic peripheral artery disease and prior coronary artery disease: Insights from the EUCLID trial

Patients with peripheral artery disease (PAD) are at heightened risk of cardiovascular morbidity and mortality. We sought to evaluate the risk of concomitant coronary artery disease (CAD) in patients with symptomatic PAD versus PAD without diagnosed CAD, and whether ticagrelor was superior to clopidogrel in reducing that risk. The EUCLID trial randomized 13,885 patients with PAD to antithrombotic monotherapy with ticagrelor or clopidogrel. CAD was defined as prior myocardial infarction (MI), percutaneous coronary intervention (PCI), or coronary artery bypass graft (CABG) surgery. Median follow-up was 30 months. Among 4032 (29%) patients with PAD and CAD, 63% had prior MI, 54% prior PCI, and 38% prior CABG. After adjustment for baseline characteristics, patients with PAD and CAD had significantly higher rates of the primary endpoint (cardiovascular death/MI/stroke, 15.3% vs 8.9%, hazard ratio (HR) 1.50, 95% CI: 1.13-1.99; p=0.005), but no statistically significant increase in acute limb ischemia (HR 1.28, 95% CI: 0.57-2.85; p=0.55) or major bleeding (HR 1.10, 95% CI: 0.49-2.48; p=0.81) versus PAD without CAD. Among patients with PAD and CAD, there was no differential treatment effect between ticagrelor versus clopidogrel for the primary efficacy endpoint (HR 1.02, 95% CI: 0.87-1.19; p=0.84), acute limb ischemia (HR 1.03, 95% CI: 0.63-1.69; p=0.89), or major bleeding (HR 1.06, 95% CI: 0.66-1.69; p=0.81). There was a statistically significant interaction between prior coronary stent placement and study treatment ( p=0.03) with a numerical reduction in the primary efficacy endpoint with ticagrelor versus clopidogrel (13.8% vs 16.8%, HR 0.82, 95% CI: 0.65-1.03; p=0.09). Patients with PAD and prior CAD had higher composite rates of cardiovascular death, MI, and ischemic stroke versus PAD without diagnosed CAD. There were no significant differences between ticagrelor and clopidogrel in cardiovascular events or major bleeding. ClinicalTrials.gov Identifier: NCT01732822.

Contemporary antiplatelet therapy in acute coronary syndromes: are there differences in outcomes and discontinuation between clopidogrel and ticagrelor?

BACKGROUND/AIM

We studied clinical outcomes and discontinuation rates in a 'real-world' population presenting with myocardial infarction treated with ticagrelor or clopidogrel.

METHODS

Between January 2012 and May 2015, 992 patients with acute myocardial infarction undergoing invasive management and adequately pre-treated with dual antiplatelet therapy were prospectively enrolled. Platelet aggregation was measured using the Multiplate analyser. Baseline characteristics, in-hospital outcomes and 1-year outcomes were collected.

RESULTS

Patients treated with ticagrelor were younger and less likely to be diabetic, have a previous myocardial infarction or present with a ST-elevation myocardial infarction (all P < 0.05). Those treated with ticagrelor also had lower CRUSADE (Can Rapid risk stratification of Unstable angina patients Suppress ADverse outcomes with Early implementation of the ACC/AHA guidelines; 20 ± 9.4 vs 23 ± 10.1, P < 0.0001) and GRACE (119 ± 28 vs 126 ± 32, P = 0.002) scores. High platelet reactivity was greatly reduced with ticagrelor compared to clopidogrel (16.1% vs 37.0%, respectively; P < 0.0001). Non-coronary artery bypass grafting-related thrombolysis in myocardial infarction major and minor bleeding occurred at similar rates in those treated with ticagrelor and clopidogrel. Rates of drug discontinuation in those treated with ticagrelor and clopidogrel were similar in hospital (20.2% vs 16.2%, P = 0.18) and between discharge and 1 year (29.9% vs 27.9%, P = 0.63). However, discontinuation due to dyspnoea, (3.3% vs 0%, P < 0.0001) and discontinuation due to any possible drug-related adverse event (9.3% vs 2.2%, P = 0.0001) was more common in those treated with ticagrelor compared to clopidogrel CONCLUSION: Ticagrelor is paradoxically being used in lower-risk patients rather than those most likely to benefit. Ticagrelor was associated with similar rates of bleeding but higher discontinuation rates due to adverse effects compared to clopidogrel.

Ticagrelor for the prevention of ischemic events in patients with prior myocardial infarction and peripheral artery disease

INTRODUCTION

Cardiovascular disease (CVD) is the main cause of death in the world. Coronary artery disease (CAD) is the most common form of CVD presentation, but the prevalence of peripheral artery disease (PAD) is increasing. Patients with polyvascular disease comprise a very high-risk population that has been infrequently studied. Areas covered: The authors review the current evidence of the efficacy and safety of ticagrelor in the setting of acute coronary syndrome and stable patients post-MI with and without PAD and summarize its pharmacokinetics, pharmacodynamics, and regulatory issues. Expert opinion: Randomized studies showed that ticagrelor is superior to clopidogrel in patients with acute coronary syndromes, and is superior to placebo in the chronic phase (>1 year) post-myocardial infarction. Sub-analyses of these studies suggest that patients with myocardial infarction and PAD, compared to patients without these characteristics, may have greater benefit with ticagrelor. Nonetheless, the global evidence about the role of ticagrelor in patients with myocardial infarction and PAD remains relatively sparse, and a prospective randomized trial testing this hypothesis would be necessary to provide more definite data regarding the efficacy and safety of ticagrelor in this very high-risk population.

P2Y12 receptor modulation of ADP-evoked intracellular Ca2+ signalling in THP-1 human monocytic cells

BACKGROUND AND PURPOSE

The Gi -coupled, ADP-activated P2Y12 receptor is well characterized as playing a key role in platelet activation via crosstalk with the P2Y1 receptor in ADP-evoked intracellular Ca2+ responses. However, there is limited knowledge on the role of P2Y12 receptors in ADP-evoked Ca2+ responses in other blood cells. Here, we investigated the role of P2Y12 receptor activation in the modulation of ADP-evoked Ca2+ responses in human THP-1 monocytic cells.

EXPERIMENTAL APPROACH

A combination of intracellular Ca2+ measurements, RT-PCR, immunocytochemistry, leukocyte isolation and siRNA-mediated gene knockdown were used to identify the role of P2Y12 receptor activation.

KEY RESULTS

ADP-evoked intracellular Ca2+ responses (EC50 2.7 μM) in THP-1 cells were abolished by inhibition of PLC (U73122) or sarco/endoplasmic reticulum Ca2+ -ATPase (thapsigargin). Loss of ADP-evoked Ca2+ responses following treatment with MRS2578 (IC50 200 nM) revealed a major role for P2Y6 receptors in mediating ADP-evoked Ca2+ responses. ADP-evoked responses were attenuated either with pertussis toxin treatment, or P2Y12 receptor inhibition with two chemically distinct antagonists (ticagrelor, IC50 5.3 μM; PSB-0739, IC50 5.6 μM). ADP-evoked responses were suppressed following siRNA-mediated P2Y12 gene knockdown. The inhibitory effects of P2Y12 antagonists were fully reversed following adenylate cyclase inhibition (SQ22536). P2Y12 receptor expression was confirmed in freshly isolated human CD14+ monocytes.

CONCLUSIONS AND IMPLICATIONS

Taken together, these data suggest that P2Y12 receptor activation positively regulates P2Y6 receptor-mediated intracellular Ca2+ signalling through suppression of adenylate cyclase activity in human monocytic cells.

Ticagrelor vs Clopidogrel After Fibrinolytic Therapy in Patients With ST-Elevation Myocardial Infarction: A Randomized Clinical Trial

Importance

The bleeding safety of ticagrelor in patients with ST-elevation myocardial infarction treated with fibrinolytic therapy remains uncertain.

Objective

To evaluate the short-term safety of ticagrelor when compared with clopidogrel in patients with ST-elevation myocardial infarction treated with fibrinolytic therapy.

Design, Setting and Participants

We conducted a multicenter, randomized, open-label with blinded end point adjudication trial that enrolled 3799 patients (younger than 75 years) with ST-segment elevation myocardial infarction receiving fibrinolytic therapy in 152 sites from 10 countries from November 2015 through November 2017. The prespecified upper boundary for noninferiority for bleeding was an absolute margin of 1.0%.

Interventions

Patients were randomized to ticagrelor (180-mg loading dose, 90 mg twice daily thereafter) or clopidogrel (300-mg to 600-mg loading dose, 75 mg daily thereafter). Patients were randomized with a median of 11.4 hours after fibrinolysis, and 90% were pretreated with clopidogrel.

Main Outcomes and Measures

The primary outcome was thrombolysis in myocardial infarction (TIMI) major bleeding through 30 days.

Results

The mean (SD) age was 58.0 (9.5) years, 2928 of 3799 patients (77.1%) were men, and 2177 of 3799 patients (57.3%) were white. At 30 days, TIMI major bleeding had occurred in 14 of 1913 patients (0.73%) receiving ticagrelor and in 13 of 1886 patients (0.69%) receiving clopidogrel (absolute difference, 0.04%; 95% CI, -0.49% to 0.58%; P < .001 for noninferiority). Major bleeding defined by the Platelet Inhibition and Patient Outcomes criteria and by the Bleeding Academic Research Consortium types 3 to 5 bleeding occurred in 23 patients (1.20%) in the ticagrelor group and in 26 patients (1.38%) in the clopidogrel group (absolute difference, -0.18%; 95% CI, -0.89% to 0.54; P = .001 for noninferiority). The rates of fatal (0.16% vs 0.11%; P = .67) and intracranial bleeding (0.42% vs 0.37%; P = .82) were similar between the ticagrelor and clopidogrel groups, respectively. Minor and minimal bleeding were more common with ticagrelor than with clopidogrel. The composite of death from vascular causes, myocardial infarction, or stroke occurred in 76 patients (4.0%) treated with ticagrelor and in 82 patients (4.3%) receiving clopidogrel (hazard ratio, 0.91; 95% CI, 0.67-1.25; P = .57).

Conclusions and Relevance

In patients younger than 75 years with ST-segment elevation myocardial infarction, delayed administration of ticagrelor after fibrinolytic therapy was noninferior to clopidogrel for TIMI major bleeding at 30 days.

Trial Registration

clinicaltrials.gov Identifier: NCT02298088.

Consensus Document ANMCO/ANCE/ARCA/GICR-IACPR/GISE/SICOA: Long-term Antiplatelet Therapy in Patients with Coronary Artery Disease

Dual antiplatelet therapy (DAPT) with aspirin and a P2Y12 receptor inhibitor is the cornerstone of pharmacologic management of patients with acute coronary syndrome (ACS) and/or those receiving coronary stents. Long-term (>1 year) DAPT may further reduce the risk of stent thrombosis after a percutaneous coronary intervention (PCI) and may decrease the occurrence of non-stent-related ischaemic events in patients with ACS. Nevertheless, compared with aspirin alone, extended use of aspirin plus a P2Y12 receptor inhibitor may increase the risk of bleeding events that have been strongly linked to adverse outcomes including recurrent ischaemia, repeat hospitalisation and death. In the past years, multiple randomised trials have been published comparing the duration of DAPT after PCI and in ACS patients, investigating either a shorter or prolonged DAPT regimen. Although the current European Society of Cardiology guidelines provide a backup to individualised treatment, it appears to be difficult to identify the ideal patient profile which could safely reduce or prolong the DAPT duration in daily clinical practice. The aim of this consensus document is to review contemporary literature on optimal DAPT duration, and to guide clinicians in tailoring antiplatelet strategies in patients undergoing PCI or presenting with ACS.

Pharmacokinetic Profiles of Ticagrelor Orodispersible Tablets in Healthy Western and Japanese Subjects

Background and Objectives

Ticagrelor is an antiplatelet agent for patients with acute coronary syndrome or a history of myocardial infarction. Two studies compared pharmacokinetic profiles of orodispersible (OD) ticagrelor tablets versus immediate-release (IR) tablets in Western and Japanese subjects.

Methods

Both studies were open-label, randomized, crossover, single-center trials. Thirty-six healthy subjects (94% white, 6% other race; Western study NCT02400333) and 42 Japanese healthy subjects (Japanese study NCT02436577) received a single 90-mg ticagrelor dose as an OD tablet [with/without water, and via a nasogastric tube (Western study only)], and an IR tablet; washout between treatments was ≥7 days. Assessments included ticagrelor and AR-C124910XX (active metabolite) plasma concentrations for pharmacokinetic analyses, and safety evaluations.

Results

In the Western study, the 90% confidence intervals (CIs) of the geometric mean ratios (GMRs) for ticagrelor and AR-C124910XX maximum plasma concentration (C_max) and area under the plasma concentration–time curve (AUC) were within the acceptance interval (80%–125%) for OD tablets (with/without water, via a nasogastric tube) versus the IR tablet; except for an ~15% lowering of ticagrelor C_max (90% CI: 76.77%–93.78%) for the OD tablet taken with water. In the Japanese study, 90% CIs of the GMRs for AUC and C_max of both ticagrelor and AR-C124910XX were all within the acceptance intervals for the OD (with/without water) versus IR tablet. No new safety issues were identified.

Conclusions

Ticagrelor administered as an OD tablet to Western (without water, and via a nasogastric tube) and Japanese (with/without water) subjects was bioequivalent to the IR tablet.

Electronic supplementary material

The online version of this article (doi:10.1007/s40261-017-0554-8) contains supplementary material, which is available to authorized users.

Platelet-targeted pharmacologic treatments as anti-cancer therapy

Platelets act as multifunctional cells participating in immune response, inflammation, allergy, tissue regeneration, and lymphoangiogenesis. Among the best-established aspects of a role of platelets in non-hemostatic or thrombotic disorders, there is their participation in cancer invasion and metastasis. The interaction of many different cancer cells with platelets leads to platelet activation, and on the other hand platelet activation is strongly instrumental to the pro-carcinogenic and pro-metastatic activities of platelets. It is thus obvious that over the last years a lot of interest has focused on the possible chemopreventive effect of platelet-targeted pharmacologic treatments. This article gives an overview of the platelet-targeted pharmacologic approaches that have been attempted in the prevention of cancer development, progression, and metastasis, including the application of anti-platelet drugs currently used for cardiovascular disease and of new and novel pharmacologic strategies. Despite the fact that very promising results have been obtained with some of these approaches in pre-clinical models, with the exclusion of aspirin, clinical evidence of a beneficial effect of anti-platelet agents in cancer is however still largely missing. Future studies with platelet-targeted drugs in cancer must carefully deal with design issues, and in particular with the careful selection of patients, and/or explore novel platelet targets in order to provide a solution to the critical issue of the risk/benefit profile of long-term anti-platelet therapy in the prevention of cancer progression and dissemination.

Evaluation of pharmacokinetic, pharmacodynamic, efficacy, and safety data of low-dose ticagrelor versus standard dose in East Asians: a systematic review

East Asians are prone to higher systemic exposure and increased risk of bleeding compared to other races after administration of antiplatelet agent(s). The aim of this systematic review was to compare and evaluate the appropriateness of a lower dose versus standard dose of ticagrelor in East Asians. A systematic search was conducted in PubMed, EMBASE, and Cochrane databases for studies comparing low versus standard doses of ticagrelor in East Asian populations; a total of seven studies were included in the review. Pharmacokinetic (PK), pharmacodynamic (PD), clinical efficacy, and safety data were collected. PK data demonstrated that the C_max and area under the curve (AUC) of ticagrelor increased dose-proportionally. PD data indicated that while the low dose of ticagrelor resulted in less antiplatelet activity in three of the five PD studies, in the other studies, there were no differences between low and standard doses. There were two clinical studies included in this review, which showed that the efficacy was similar between the low and standard doses, but both studies were limited by the number of patients included. While there were generally greater incidence of adverse events observed in the standard ticagrelor dose, the magnitude or actual difference between the two doses is difficult to determine due to lack of consistent data. In East Asians, the appropriateness of the low-dose ticagrelor cannot be determined based on the currently available evidence. Additional large-scale and longer duration studies are warranted.

Blockade of protease-activated receptor-4 (PAR4) provides robust antithrombotic activity with low bleeding

Antiplatelet agents are proven efficacious treatments for cardiovascular and cerebrovascular diseases. However, the existing drugs are compromised by unwanted and sometimes life-threatening bleeding that limits drug usage or dosage. There is a substantial unmet medical need for an antiplatelet drug with strong efficacy and low bleeding risk. Thrombin is a potent platelet agonist that directly induces platelet activation via the G protein (heterotrimeric guanine nucleotide-binding protein)-coupled protease-activated receptors PAR1 and PAR4. A PAR1 antagonist is approved for clinical use, but its use is limited by a substantial bleeding risk. Conversely, the potential of PAR4 as an antiplatelet target has not been well characterized. Using anti-PAR4 antibodies, we demonstrated a low bleeding risk and an effective antithrombotic profile with PAR4 inhibition in guinea pigs. Subsequently, high-throughput screening and an extensive medicinal chemistry effort resulted in the discovery of BMS-986120, an orally active, selective, and reversible PAR4 antagonist. In a cynomolgus monkey arterial thrombosis model, BMS-986120 demonstrated potent and highly efficacious antithrombotic activity. BMS-986120 also exhibited a low bleeding liability and a markedly wider therapeutic window compared to the standard antiplatelet agent clopidogrel tested in the same nonhuman primate model. These preclinical findings define the biological role of PAR4 in mediating platelet aggregation. In addition, they indicate that targeting PAR4 is an attractive antiplatelet strategy with the potential to treat patients at a high risk of atherothrombosis with superior safety compared with the current standard of care.

The protective effect of ticagrelor on renal function in a mouse model of sepsis-induced acute kidney injury

Platelets are traditionally considered to be essential components of primary hemostasis. Recent investigations have revealed that platelets can be activated in patients with sepsis and are implicated in the development of sepsis and sepsis-induced-acute kidney injury (SAKI). In the present study, ticagrelor was used to induce a mouse model of SAKI by cecal ligation and puncture. It was found that ticagrelor could inhibit platelet activity, decrease the levels of interleukin-1β and serum creatinine, reduce infiltration of neutrophils in renal tissue, and attenuate cell apoptosis in the kidney. The results suggested that ticagrelor could protect renal function by inhibiting inflammation, recruitment of neutrophils into the kidney, and cell apoptosis in renal tissue. Thus, the findings might provide new strategies for preventing SAKI.

P2Y12 receptor inhibitors: an evolution in drug design to prevent arterial thrombosis

INTRODUCTION

P2Y12 inhibitors are a critical component of dual antiplatelet therapy (DAPT), which is the superior strategy to prevent arterialthrombosis in patients with acute coronary syndromes (ACS) and undergoing stent implantation.. Areas covered: Basic science articles, clinical studies, and reviews from 1992-2017 were searched using Pubmed library to collet impactful literature. After an introduction to the purinergic receptor biology, this review summarizes current knowledge on P2Y12 receptor inhibitors. Furthermore, we describe the subsequent improvements of next-generation P2Y12 receptor inhibitors facing the ambivalent problem of bleeding events versus prevention of arterial thrombosis in a variety of clinical settings. Therefore, we summarize data from relevant preclinical and clinical trials of currently approved P2Y12 receptor inhibitors (clopidogrel, prasugrel, ticagrelor, cangrelor) and provide strategies of drug switching and management of bleeding events. Expert opinion: An enormous amount of pharmacologic and clinical data is available for the application of P2Y12 receptor inhibitors. Today prasugrel, ticagrelor and clopidogrel are the standard of care drugs during dual antiplatelet therapy for ACS patients, but have considerable rates of bleeding. Recent and future clinical trials will provide evidence for subsequent escalation and de-escalation strategies of P2Y12 receptor inhibition. These data may pave the way for an evidence-based, individualized P2Y12 receptor inhibitor therapy.

Prevention of minor myocardial injury after elective percutaneous coronary intervention: comparison of ticagrelor versus clopidogrel

BACKGROUND

Elective percutaneous coronary intervention (ePCI) may cause minor elevation of cardiac enzymes, so-called minor myocardial injury (MMI) which can be due to different pathophysiological mechanism (e.g. distal embolisation, side branch occlusion, increased platelet activation triggered by the intracoronary metallic stents). We aimed to compare the effectiveness of ticagrelor versus clopidogrel for the prevention of MMI and major adverse clinical events (MACEs) after ePCI.

METHODS

Study population consisted of two groups of patients based on the treatment: Group I, receiving clopidogrel (n = 104), Group II, receiving ticagrelor (n = 96). Cardiac troponin I (cTnI), CK-MB were studied before and 12 hours after the procedure. Elevation of cTnI greater than 0.06 ng/ml was considered as MMI. All patients were also evaluated for the MACEs (death, myocardial infarction, stroke and transient ischaemic attack).

RESULTS

Fifty-two of 200 patients (26%) had MMI after the procedure. The minor myocardial injury was significantly more prevalent in clopidogrel group than that of ticagrelor group (33% vs. 19%, p = .03). Myocardial infarction (MI) and MACEs were significantly higher in the clopidogrel group (15% vs. 6%, for MI, p = .04; 16% vs. 6%, for MACEs, p = .03, respectively). Multivariate analysis demonstrated antiplatelet treatment, saphenous graft intervention, type-C lesion as independent predictors of MMI.

CONCLUSIONS

Present study showed that the combination of ticagrelor and aspirin was more effective than combination of clopidogrel and aspirin in decreasing MMI and MACEs after elective stenting.

Design and Rationale for comParison Between ticagreLor and clopidogrEl on mIcrocirculation in Patients with Acute cOronary Syndrome Undergoing Percutaneous Coronary Intervention (PLEIO) Trial

It has been previously demonstrated that ticagrelor can reduce mortality compared to clopidogrel in acute coronary syndrome (ACS) patients. However, the mechanism for this mortality reduction remains uncertain. The objective of the present study is to assess the impact of chronic ticagrelor treatment on microvascular circulation. A total of 120 participants aged 20–85 years with clinical diagnosis of ACS will be randomized in a 1:1 fashion to the following two groups: ticagrelor 90 mg twice daily; clopidogrel 75 mg once daily. To evaluate the status of microcirculation, the primary end point is coronary microvascular dysfunction measured using an index of microcirculatory resistance (IMR) at 6 months after receiving the study agent. The purpose of this trial is to investigate whether ticagrelor, beyond its antiplatelet efficacy, could improve coronary microcirculation more effectively than clopidogrel for patients with ACS.

Current and future antiplatelet therapies: emphasis on preserving haemostasis

Antiplatelet drugs, such as aspirin, P2Y₁₂ antagonists, and glycoprotein (GP) IIb/IIIa inhibitors, have proved to be successful in reducing the morbidity and mortality associated with arterial thrombosis. These agents are, therefore, the cornerstone of therapy for patients with acute coronary syndromes. However, these drugs all carry an inherent risk of bleeding, which is associated with adverse cardiovascular outcomes and mortality. Thus, the potential benefits of more potent, conventional antiplatelet drugs are likely be offset by the increased risk of bleeding. Data from experiments in vivo have highlighted potentially important differences between haemostasis and thrombosis, raising the prospect of developing new antiplatelet drugs that are not associated with bleeding. Indeed, in preclinical studies, several novel antiplatelet therapies that seem to inhibit thrombosis while maintaining haemostasis have been identified. These agents include inhibitors of phosphatidylinositol 3-kinase-β (PI3Kβ), protein disulfide-isomerase, activated GPIIb/IIIa, GPIIb/IIIa outside-in signalling, protease-activated receptors, and platelet GPVI-mediated adhesion pathways. In this Review, we discuss how a therapeutic ceiling has been reached with existing antiplatelet drugs, whereby increased potency is offset by elevated bleeding risk. The latest advances in our understanding of thrombus formation have informed the development of new antiplatelet drugs that are potentially safer than currently available therapies.

Antiplatelet therapy – ticagrelor

Ticagrelor, a cyclopentyltriazolopyrimidine (CPTP), is the representative of a new chemical class of P2Y12 receptor inhibitors that differ from thienopyridines (ticlopidin, clopidogrel, prasugrel) as ticagrelor is not a prodrug requiring active biotransformation by cytochromes in the liver and thus is characterized by a more rapid, more effective and more consistent platelet inhibition than ticlopidin or clopidogrel. An extensive study program for dose finding and safety for AZD6140 (DISPERSE studies) and a large-scaled phase III trial (PLATO) were undertaken on more than 18 000 patients for validation of efficacy and safety. In the PLATO trial, patients presenting with the broad spectrum of ACS, i.e. unstable angina, non-STEMI or STEMI, were randomized to ticagrelor (Brilique, Brilinta) or clopidogrel within 24 hours after onset of symptoms, regardless whether they were allocated to a planned invasive or conservative treatment. Compared to clopidogrel, ticagrelor reduced rates of the primary endpoint consisting of cardiovascular death, non-fatal MI, or stroke, without an excess of the primary safety endpoint that was PLATO-defined major bleedings. Results from the pre-specified confirmatory subgroup of patients undergoing planned invasive treatment was consistent with PLATO main trial. In addition, the primary endpoint, as well as CV death and all cause death were consistently reduced with ticagrelor in numerous exploratory subgroups including STEMI patients, those planned for non-invasive treatment, patients undergoing CABG, patients with renal failure, and those with diabetes mellitus, although patients were pretreated before coronary angiography and patients with clopidogrel pretreatment were not excluded. Conclusions: The pharmacological properties and convincing study results of the PLATO trial have stimulated a paradigm change for dual antiplatelet therapy. The new ESC guidelines on the management of ACS without ST segment elevation recommend the use of clopidogrel only when a new antiplatelet drug, e. g. ticagrelor or prasugrel is not available or contraindicated.

Head to head comparison of Prasugrel versus Ticagrelor in patients with acute coronary syndrome: a systematic review and meta-analysis of randomized trials

Background

Prasugrel and Ticagrelor are emerging antiplatelet drugs that might have the potential to replace currently used antiplatelet agents. Previous analyses comparing prasugrel with ticagrelor mainly focused on an indirect comparison whereas direct comparison was reported only in a few recently published trials. We aimed to systematically carry out a head to head comparison of the adverse clinical outcomes which were associated with prasugrel versus ticagrelor in patients with acute coronary syndrome (ACS).

Methods

Studies comparing prasugrel with ticagrelor (head to head comparison) were searched from online databases. Adverse cardiovascular outcomes were considered as the primary endpoints whereas bleeding outcomes were considered as the secondary endpoints in this analysis. The latest version of the RevMan software was used to carry out subgroup analyses whereby odds ratios (OR) with 95% confidence intervals (CI) and the calculated probability (P) were generated.

Results

Four studies with a total number of 563 patients (2012 – 2016) were included (282 patients were treated with prasugrel and 281 patients were treated with ticagrelor). Results of this analysis did not show any significant difference in mortality between prasugrel and ticagrelor with OR: 1.52, 95% CI: 0.42 – 5.45; P = 0.52. In addition, myocardial infarction, major adverse cardiac events, stroke and stent thrombosis were also not significantly different with OR: 0.59, 95% CI: 0.08 – 4.58; P = 0.62, OR: 0.91, 95% CI: 0.37 – 2.21; P = 0.83, OR: 0.60, 95% CI: 0.08 – 4.58; P = 0.62 and OR: 0.59, 95% CI: 0.08 – 4.58; P = 0.62 respectively.

Thrombolysis in myocardial infarction (TIMI) defined minor bleeding, and minimal bleeding were also not significantly different between these two newer antiplatelet agents with OR: 3.11, 95% CI: 0.48 – 19.94; P = 0.23, and OR: 2.39, 95% CI: 0.35 – 16.42; P = 0.38 respectively. Moreover, bleeding defined by the academic research consortium was also similarly manifested with OR: 0.92, 95% CI: 0.39 – 2.13; P = 0.84.

Conclusion

In patients with ACS, both prasugrel and ticagrelor showed similar adverse cardiovascular outcomes and bleeding events. No significant difference was observed between these two newer antiplatelet agents during this head to head comparison. However, upcoming trials with long term follow up periods might be expected to completely solve this important clinical issue.

Platelets, inflammation and anti-inflammatory effects of antiplatelet drugs in ACS and CAD

Platelets play a pivotal role in chronic inflammation leading to progression of atherosclerosis and acute coronary events. Recent discoveries on novel mechanisms and platelet-dependent inflammatory targets underpin the role of platelets to maintain a chronic inflammatory condition in cardiovascular disease. There is strong and clinically relevant crosslink between chronic inflammation and platelet activation. Antiplatelet therapy is a cornerstone in the prevention and treatment of acute cardiovascular events. The benefit of antiplatelet agents has mainly been attributed to their direct anti-aggregatory impact. Some anti-inflammatory off-target effects have also been described. However, it is unclear whether these effects are secondary due to inhibition of platelet activation or are caused by direct distinct mechanisms interfering with inflammatory pathways. This article will highlight novel platelet associated targets that contribute to inflammation in cardiovascular disease and elucidate mechanisms by which currently available antiplatelet agents evolve anti-inflammatory capacities, in particular by carving out the differential mechanisms directly or indirectly affecting platelet mediated inflammation. It will further illustrate the prognostic impact of antiplatelet therapies by reducing inflammatory marker release in recent cardiovascular trials.

Why does ticagrelor induce dyspnea?

In studies that compared the reversible P2Y12 inhibitor ticagrelor with the irreversible inhibitor clopidogrel, dyspnea was observed more frequently among ticagrelor-treated patients than among clopidogreltreated patients. Because dyspnea was not associated with acidosis, pulmonary or cardiac dysfunction, alterations in the mechanisms and pathways of the sensation of dyspnea may be involved in its pathogenesis. It has been hypothesised that the sensation of dyspnea in ticagrelor-treated patients is triggered by adenosine, because ticagrelor inhibits its clearance, thereby increasing its concentration in the circulation. However, dipyridamole, a much stronger inhibitor of adenosine clearance than ticagrelor, usually does not cause dyspnea. We hypothesise that inhibition of P2Y12 on sensory neurons increases the sensation of dyspnea, particularly when reversible inhibitors are used. We base our hypothesis on the following considerations: 1) cangrelor and elinogrel, which, like ticagrelor, are reversible P2Y12 inhibitors, also increase the incidence of dyspnea;2) it is biologically plausible that inhibition of P2Y12 on sensory neurons increases the sensation of dyspnea;3) inhibition of P2Y12 on platelets (which do not have a nucleus) by clopidogrel is permanent, despite the once daily administration and the short plasma half-life of the inhibitor;4) in contrast, inhibition of P2Y12 on neurons by clopidogrel may be temporary and transient, because neurons have a nucleus and can therefore rapidly replace the inhibited receptors with newly synthetised ones;5) inhibition of P2Y12 on neurons by reversible inhibitors is permanent, because the plasma drug concentration is maintained high by repeated dosing, in order to ensure permanent inhibition of platelet P2Y12.

Viewpoint: Reversible nature of platelet binding causing transfusion-related acute lung injury (TRALI) syndrome may explain dyspnea after ticagrelor and elinogrel

There may be a universal mechanism explaining dyspnea after ticagrelor and elinogrel, namely, transfusion-related acute lung injury (TRALI). Indeed, recent clinical trials with ticagrelor (DISPERSE, DISPERSE-II, and PLATO), and elinogrel (INNOVATE PCI) revealed double-digit rates of dyspnea after novel reversible antiplatelet agents. In contrast, dyspnea is not associated with conventional non-reversible agents such as aspirin, or thienopyridines (ticlopidine, clopidogrel, or prasugrel) suggesting distinct mechanism of shortness of breath after ticagrelor and elinogrel. The adenosine hypothesis has been offered to explain such adverse association. However, despite obvious similarity between ticagrelor and adenosine molecules, the chemical structure of elinogrel is entirely different. In fact, ticagrelor is a cyclopentyl-triazolo-pyrimidine, while elinogrel is a quinazolinedione. Since both agents cause dyspnea, the adenosine hypothesis is no longer valid. In contrast, the reversible nature of platelet inhibition attributable to both ticagrelor and elinogrel causing premature cell ageing, apoptosis, impaired turnover due to sequestration of overloaded, exhausted platelets in the pulmonary circulation are among potential autoimmune mechanism(s) resulting in the development of a TRALI-like reaction, and frequent dyspnea. Despite expected benefit for better bleeding control, further development of reversible antithrombins is severely limited due to the existence of a potentially universal serious adverse event, such as TRALI-syndrome with dyspnea as a predominant clinical manifestation. Since TRALI is an established number one contributor to mortality after blood transfusions, ticagrelor death “benefit”in PLATO is challenged further.