cangrelor and Thrombosis

Cangrelor is the only currently available intravenous platelet P2Y

Topics: Acute Coronary Syndrome; Adenosine Monophosphate; Animals; Humans; Percutaneous Coronary Intervention; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Risk Assessment; Risk Factors; Thrombosis; Treatment Outcome

Thrombotic events such as myocardial infarction or stent thrombosis are the major cause of adverse outcomes in patients undergoing percutaneous coronary intervention (PCI). While current antiplatelet agents, anticoagulants, and PCI techniques have reduced the risk of thrombotic events in PCI-treated patients, a considerable hazard still remains. Cangrelor is an intravenous P2Y12 receptor antagonist that provides a rapid onset and maximal platelet inhibition, which is quickly reversible. In the large-scale CHAMPION PHOENIX trial, cangrelor was shown to reduce ischemic events significantly, including myocardial infarction and stent thrombosis, without increasing the risk of severe bleeding across the full spectrum of patients undergoing PCI, with substantial benefits in all patient subgroups examined. The pharmacologic profile of cangrelor makes it a valuable addition to the armamentarium of physicians providing care to a broad range of patients with coronary artery disease. Cangrelor is currently approved for reducing thrombotic events in patients undergoing PCI who have not been pretreated with a P2Y12 receptor inhibitor and are not receiving a glycoprotein IIb/IIIa inhibitor. Future studies are needed to determine the role of cangrelor in other clinical settings, such as upstream therapy in ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation acute coronary syndrome (NSTE-ACS), and as a bridge to coronary artery bypass graft (CABG) or other non-cardiac surgeries in patients who require ongoing adenosine diphosphate receptor blockade.

Topics: Adenosine Monophosphate; Animals; Clinical Trials as Topic; Coronary Artery Disease; Humans; Myocardial Infarction; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Thrombosis

Despite advances in antiplatelet therapy, the optimum antithrombotic regimen during percutaneous coronary intervention (PCI) remains to be determined. Cangrelor is an intravenous, reversibly-binding platelet P2Y12 receptor antagonist with ultra-rapid onset and offset of action that is approved in Europe and United States for use in patients undergoing PCI. This article describes the background for the development of cangrelor, the biology, pharmacology and clinical evidence supporting its use, and its likely position in the future.. The role of the platelet P2Y12 receptor in platelet biology and the implications of this for atherothrombotic disease are described. Currently unmet needs in antithrombotic management during and after PCI are discussed followed by a description of the chemistry, pharmacokinetics and pharmacodynamics of cangrelor, including its interactions with oral thienopyridines. Subsequently, the clinical trial evidence supporting its adoption into clinical practice is reviewed, including the evidence indicating its superiority over a strategy based on clopidogrel treatment alone. Expert commentary: The current status and future potential of cangrelor is discussed, including a view of its place in current clinical practice.

Topics: Adenosine Monophosphate; Administration, Intravenous; Clopidogrel; Humans; Percutaneous Coronary Intervention; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Thrombosis; Ticlopidine

Acute coronary syndromes (ACS) are one of the leading causes of death worldwide. Several landmark trials, followed by a widespread introduction of new agents, have significantly improved ACS outcomes in recent years. However, despite the use of contemporary therapy, a substantial number of ACS patients continue to suffer from cardiovascular events. Areas covered: The aim of this review was to summarize available data on innovative drugs and pharmacological strategies that have potential to amend the current ACS therapy. We present the results of recent large clinical trials, as well as insights from ongoing phase III and phase IV studies, exploring the value of new strategies for the improvement of outcomes in ACS. Expert opinion: More potent platelet inhibition, more profound lipid reduction and possibly anti-inflammatory action are considered to have potential to further reduce the rates of adverse cardiovascular and thrombotic events in ACS patients. 'Hit fast, hit hard' approach regarding novel antiplatelet and lipid-lowering therapy seems attractive, but it has to be considered that these strategies may be associated with increased adverse events rate. Introduction of cangrelor and ezetimibe, and potentially future recognition of proprotein convertase subtilisin/kexin type 9 antibodies, are likely to alter the landscape of ACS pharmacotherapy.

Topics: Acute Coronary Syndrome; Adenosine Monophosphate; Antibodies, Monoclonal; Anticholesteremic Agents; Clinical Trials as Topic; Drug Discovery; Ezetimibe; Humans; PCSK9 Inhibitors; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Thrombosis; Treatment Outcome

Dual antiplatelet therapy is the standard of care for patients with acute coronary syndromes or with recent coronary stents implantation. P2Y12 receptor antagonists have shown to reduce the risk of recurrent ischemic events among these patients, at the expense of an increased risk of bleeding. Cangrelor is a novel, intravenous, short-acting, reversible platelet P2Y12 inhibitor, which has been evaluated for the treatment of arterial thrombosis.. Studies on the pharmacological characteristics of cangrelor and clinical trials were retrieved by a PubMed literature search.. Cangrelor has been tested in patients with coronary artery diseases undergoing percutaneous coronary intervention and as bridging therapy for patients undergoing coronary artery bypass graft. The rapid peak of action allows a fast and complete inhibition of platelet aggregation; the rapid offset is advantageous in case of bleeding complications; and finally, the intravenous administration also makes this drug suitable for patients unable to consume oral medications. Unfortunately, the large clinical trials evaluating cangrelor in percutaneous coronary intervention did not show superiority to the standard antiplatelet therapy, and its future use in this setting still needs to be better assessed. Conversely, when used as bridging therapy to coronary artery bypass graft, cangrelor showed promising results.

Topics: Adenosine Monophosphate; Coronary Artery Disease; Hemorrhage; Humans; Percutaneous Coronary Intervention; Platelet Aggregation Inhibitors; Thrombosis

Cangrelor is a new parenteral adenosine diphosphate P2Y12 receptor inhibitor with rapid, profound and reversible inhibition of platelet activity. The aim of this meta-analysis was to evaluate efficacy and safety of this new agent in patients undergoing percutaneous coronary intervention (PCI). We searched PubMed, Cochrane Library, EMBASE, Web of Science and CINAHL databases from the inception through April 2013. Randomized controlled trials (RCTs) comparing cangrelor with control (clopidogrel/placebo) were selected. We used the random-effects models to calculate the risk ratio. The primary efficacy outcome was risk of myocardial infarction, and the primary safety outcome was TIMI major bleeding at 48 h. Three RCTs included a total of 25,107 participants. Effects of Cangrelor were not different against comparators for myocardial infarction (MI) (Risk ratio [RR] 0.94, 95% confidence interval [CI] 0.78-1.13) and all-cause mortality (RR 0.72, 95% CI 0.36-1.43). However, cangrelor significantly reduced the risk of ischemia-driven revascularization (RR 0.72, 95% CI 0.52-0.98), stent thrombosis (RR 0.60, 95% CI 0.44-0.82) and Q wave MI (RR 0.53, 95% CI 0.30-0.92) without causing extra major bleeding (Thrombolysis in Myocardial infarction criteria) and severe or life-threatening bleeding (Global utilization of streptokinase and tissue plasminogen activator for occluded coronary arteries criteria). Separate analysis against only clopidogrel also showed similar findings except Q wave MI outcome. Use of cangrelor during PCI might reduce the risk of ischemia-driven revascularization and stent thrombosis, without causing extra major bleeding.

Topics: Adenosine Monophosphate; Female; Hemorrhage; Humans; Male; Models, Biological; Myocardial Infarction; Percutaneous Coronary Intervention; Postoperative Complications; PubMed; Purinergic P2Y Receptor Antagonists; Randomized Controlled Trials as Topic; Receptors, Purinergic P2Y12; Thrombosis

Cangrelor is a new antiplatelet agent that has been used in percutaneous coronary intervention (PCI) with mixed results. We aimed to review the evidence on the efficacy of cangrelor in comparison to clopidogrel in reducing ischaemic endpoints at 48 hours in patients undergoing PCI in large randomised trials.. In three large clinical trials involving 25,107 participants, the risk of the primary composite efficacy endpoint of death, MI and ischaemia-driven revascularisation at 48 hours, (pooled OR 0.94; 95% CI: 0.77-1.14, p=0.51, I2=68%), death from all cause (pooled OR 0.72, 95% CI: 0.36-1.43, p=0.34, I2=52%), myocardial infarction (pooled OR 0.94, 95% CI: 0.77-1.14, p=0.51, I2=68%) was not significantly different between cangrelor and clopidogrel. Likewise, severe or life-threatening bleeding was similar between cangrelor and clopidogrel (pooled OR 1.21, 95% CI: 0.70-2.12, p=0.50, I2=0%). The risk of stent thrombosis (pooled OR 0.59, 95% CI: 0.43-0.81, p=0.001, I2=0%), Q-wave myocardial infarction (pooled OR 0.53, 95% CI: 0.30-0.92, p=0.02, I2=0%) and ischaemia-driven revascularisation (pooled OR 0.71, 95% CI: 0.52-0.98, p=0.04, I2=0%) was lower in the cangrelor group.. Based on this meta-analysis, we did not find any difference in the risk of the primary composite efficacy endpoint of all-cause death, ischaemia-driven revascularisation, and myocardial infarction at 48hours between cangrelor and clopidogrel use. Given that cangrelor was associated with a lower risk of stent thrombosis, ischaemia-driven revascularisation and Q-wave myocardial infarction compared to clopidogrel, cangrelor can be considered as a suitable alternative during PCI.

Topics: Adenosine Monophosphate; Clopidogrel; Female; Humans; Male; Middle Aged; Myocardial Infarction; Percutaneous Coronary Intervention; Platelet Aggregation Inhibitors; Randomized Controlled Trials as Topic; Stents; Thrombosis; Ticlopidine

ADP plays a pivotal role in localized platelet activation and recruitment, and, with that, in the maintenance of thrombus integrity, making it a suitable target for the control of intravascular thrombosis. The limited distribution of one of its receptors, the P2Y12 receptor, primarily to platelets makes it an especially attractive pharmacologic target. For the last several decades the thienopyridine family of P2Y12 antagonists have provided the vast majority of clinical data confirming the clinical benefit of selective P2Y12 inhibition. Recently, new thienopyridine plus nonthienopyridine P2Y12 antagonists have become available or are being studied that will further improve our treatment of patients with coronary disease.

Topics: Acute Coronary Syndrome; Adenosine; Adenosine Monophosphate; Clopidogrel; Coronary Artery Disease; Humans; Myocardial Infarction; Piperazines; Prasugrel Hydrochloride; Purinergic P2Y Receptor Antagonists; Quinazolinones; Stents; Sulfonamides; Thiophenes; Thrombosis; Ticagrelor; Ticlopidine

The important role of the P2Y12 receptor in amplification of platelet activation and associated responses and the limitations associated with clopidogrel therapy have led to the development of novel inhibitors of this receptor. Three reversibly-binding P2Y12 inhibitors are in phase 3 development, ticagrelor, cangrelor and elinogrel. The pharmacology and clinical trial data for each of these inhibitors are discussed and compared with relevant data for the thienopyridines clopidogrel and prasugrel.

Topics: Adenosine; Adenosine Monophosphate; Animals; Clinical Trials, Phase III as Topic; Clopidogrel; Humans; Piperazines; Platelet Activation; Prasugrel Hydrochloride; Protein Binding; Purinergic P2Y Receptor Antagonists; Quinazolinones; Sulfonamides; Thiophenes; Thrombosis; Ticagrelor; Ticlopidine

Atherothrombosis is an acute complication that develops on the surface of a ruptured atheromatous plaque or as a consequence of endothelial erosion that may cause myocardial infarction or ischemic stroke. Anti-platelet therapy has been highly effective at reducing atherothrombotic risk. However, patients continue to experience thrombotic events despite the use of agents such as aspirin and clopidogrel. Many of these events occur, in part, because of the inadequate response to these drugs. This has prompted the pursuit of novel agents with aspirations of optimizing anti-platelet therapy. New opportunities have emerged to address the deficiencies in current anti-platelet agents. Among these are thrombin receptor antagonists, such as SCH530348 and P2Y12 receptor antagonists, such as prasugrel, cangrelor, and AZD6140. The patents describe these novel compounds and compositions, their ability to inhibit platelet activation and/or aggregation and their use in the treatment of atherothrombotic diseases. These drugs have pharmacologic properties that translate into increased potency, more rapid onset of action, and less variability in response compared to standard therapy. In this review, we highlight the current data on these potential drugs and the role they could play in atherothrombotic disease.

Topics: Adenosine Monophosphate; Animals; Humans; Piperazines; Platelet Aggregation Inhibitors; Prasugrel Hydrochloride; Purinergic P2 Receptor Antagonists; Receptors, Purinergic P2Y12; Receptors, Thrombin; Thiophenes; Thrombosis

ADP is one of the most important mediators of both physiologic hemostasis and thrombosis. Development and utilization of agents that block ADP receptors on the platelet membrane, namely thienopyridines, has represented a major advancement for treatment of patients undergoing percutaneous coronary interventions and those with acute coronary syndromes. Currently, clopidogrel, a second-generation thienopyridine that inhibits the ADP P2Y(12) receptor, represents the treatment of choice, in addition to aspirin, for the prevention of stent thrombosis. Further, long-term adjunctive use of this ADP P2Y(12) receptor antagonist is also associated with improved clinical outcomes in high-risk patients, and represents the standard of care for these patients. Despite the unambiguous clinical benefit associated with clopidogrel, accumulating experience with this drug has also led to identification of some of its drawbacks, which are related to inadequate platelet inhibition with standard dosage regimens as well as to its irreversible antiplatelet effects. This has led to the questioning of currently recommended clopidogrel dosage regimens as well as to the development of novel and more potent ADP P2Y(12) receptor antagonists, some of which are also reversible agents. Numerous studies are currently ongoing with the objective of demonstrating how more potent platelet inhibition using higher loading and maintenance dose regimens of clopidogrel or novel ADP P2Y(12) receptor antagonists - such as prasugrel, ticagrelor (AZD 6140) and cangrelor - will affect clinical outcomes. This article reviews the current knowledge of platelet ADP P2Y(12) receptor antagonism and the projected developments in this field.

Topics: Adenosine; Adenosine Monophosphate; Angioplasty, Balloon, Coronary; Blood Platelets; Clopidogrel; Coronary Disease; Humans; Membrane Proteins; Piperazines; Platelet Aggregation Inhibitors; Prasugrel Hydrochloride; Purinergic P2 Receptor Antagonists; Receptors, Purinergic P2Y12; Thiophenes; Thrombosis; Ticagrelor; Ticlopidine

The dual role of P2Y1 and P2Y12 receptors in platelet aggregation by ADP has been firmly established, based on the action of selective inhibitors, gene targeting in mice and human genetic evidence. Both of these receptor subtypes constitute targets for antithrombotic agents, and compounds with a dual action might also be of interest. However, the agents currently on the market (ticlopidine and clopidogrel), or known to be in development (cangrelor, AZD-6140 and prasugrel), all target the P2Y12 receptor. The thienopyridines (ticlopidine, clopidogrel and prasugrel) irreversibly inactivate the P2Y12 receptor via the covalent binding of an active metabolite generated in the liver, while the other compounds are competitive antagonists. Cangrelor, an ATP derivative, is suitable for intravenous perfusion, whereas AZD-6140 is in clinical development as an orally active agent.

Topics: Adenosine Monophosphate; Animals; Clopidogrel; Humans; Mice; Platelet Aggregation; Platelet Aggregation Inhibitors; Purinergic P2 Receptor Antagonists; Thrombosis; Ticlopidine

An important role for adenosine diphosphate (ADP)-induced platelet activation and aggregation was proposed more than 40 years ago. The clinical use of clopidogrel, a prodrug of an irreversible P2Y (12) antagonist, has further proved the relevance of inhibiting signaling via the platelet-specific P2Y (12) ADP receptor in the prevention of cardiovascular events. Pharmacological studies at AstraZeneca R&D Charnwood have identified direct, selective, and competitive P2Y (12) antagonists, including cangrelor (also known as AR-C69931MX), which is suitable for intravenous administration, and AZD6140, which is suitable for oral administration. In preclinical use, these compounds predictably and effectively inhibited platelet aggregation without significant increases in bleeding time. In clinical use, these compounds may have significant advantages over current antiplatelet agents. This article summarizes preclinical and clinical data on cangrelor and AZD6140 and discusses the potential of these compounds as novel antiplatelet therapies.

Topics: Adenosine; Adenosine Diphosphate; Adenosine Monophosphate; Administration, Oral; Animals; Arterial Occlusive Diseases; Clinical Trials as Topic; Dogs; Double-Blind Method; Drug Evaluation, Preclinical; Female; Fibrinolytic Agents; Humans; Injections, Intravenous; Male; Membrane Proteins; Platelet Aggregation; Platelet Aggregation Inhibitors; Purinergic P2 Receptor Antagonists; Pyridines; Rabbits; Randomized Controlled Trials as Topic; Receptors, Purinergic P2Y12; Thrombosis; Ticagrelor

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Animals; Drug Combinations; Humans; Myocardial Ischemia; Platelet Activation; Platelet Aggregation; Purinergic P2 Receptor Antagonists; Receptors, Purinergic P2; Thrombosis; Tissue Plasminogen Activator

Thrombotic events are reduced with cangrelor, an intravenous P2Y. CHAMPION PHOENIX was a double-blind, placebo-controlled trial that randomized patients undergoing percutaneous coronary intervention to cangrelor or clopidogrel. For this analysis, we evaluated the efficacy of cangrelor in the first 2 hours postrandomization with regards to the primary end point (death, myocardial infarction, ischemia-driven revascularization, or stent thrombosis). Sensitivity analyses were performed evaluating a secondary, post hoc end point (death, Society of Coronary Angiography and Intervention myocardial infarction, ischemia-driven revascularization, or Academic Research Consortium definite stent thrombosis).. The reductions in ischemic events and overall efficacy seen with cangrelor in CHAMPION PHOENIX occurred early and during the period of time in which patients were being actively treated with cangrelor. These findings provide evidence that supports the importance of potent platelet inhibition during percutaneous coronary intervention. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01156571.

Topics: Adenosine Monophosphate; Clopidogrel; Humans; Myocardial Infarction; Percutaneous Coronary Intervention; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Thrombosis; Treatment Outcome

To describe the characteristics and outcomes of patients receiving bailout glycoprotein IIb/IIIa inhibitors (GPI) for thrombotic complications of percutaneous coronary intervention (PCI) in a large, contemporary trial.. In the CHAMPION PHOENIX trial, the use of GPI was restricted to bailout for thrombotic complications. We describe the characteristics and outcomes of patients requiring bailout GPI compared to patients not receiving GPIs, with adjustment through propensity-score. A multivariable model was constructed to identify independent correlates associated with bailout GPI use. A total of 380 out of 10,942 patients received GPI (3.5%); GPI patients were younger, more frequently male, more likely to present with ST segment elevation myocardial infarction and less frequently treated with cangrelor. At 48 h, GPI patients experienced higher rates of the primary composite outcome of death, myocardial infarction, ischemia-driven revascularization, or stent thrombosis (ST) (19.2% vs 4.8%; adjusted OR: 5.65(4.08, 7.82), p < 0.0001) and a higher rate of GUSTO severe or moderate bleeding (2.6% vs 0.4% adjusted OR: 4.90 (1.98, 12.18), p = 0.0006) compared with non GPI patients. Independent correlates of GPI use were STEMI, use of unfractionated heparin, drug-eluting stents and longer procedure duration.. In a large contemporary trial, patients receiving bailout GPI for thrombotic complications of PCI experienced very high risks of both ischemic and bleeding complications, suggesting that prevention of periprocedural complications rather than bailout GPI may be preferable.. http://www.clinicaltrials.gov identifier: NCT01156571.

Topics: Adenosine Monophosphate; Aged; Double-Blind Method; Female; Heart Diseases; Humans; Male; Middle Aged; Percutaneous Coronary Intervention; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; ST Elevation Myocardial Infarction; Thrombosis; Treatment Outcome

This study sought to evaluate the clinical impact of intraprocedural stent thrombosis (IPST), a relatively new endpoint.. In the prospective, double-blind, active-controlled CHAMPION PHOENIX (Clinical Trial Comparing Cangrelor to Clopidogrel Standard of Care Therapy in Subjects Who Require Percutaneous Coronary Intervention) trial, cangrelor significantly reduced periprocedural and 30-day ischemic events in patients undergoing percutaneous coronary intervention (PCI), including IPST.. An independent core laboratory blinded to treatment assignment performed a frame-by-frame angiographic analysis in 10,939 patients for the development of IPST, defined as new or worsening thrombus related to stent deployment at any time during the procedure. Adverse events were adjudicated by an independent, blinded clinical events committee.. IPST developed in 89 patients (0.8%), including 35 of 5,470 (0.6%) and 54 of 5,469 (1.0%) patients in the cangrelor and clopidogrel arms, respectively (odds ratio: 0.65; 95% confidence interval: 0.42 to 0.99; p = 0.04). Compared to patients without IPST, IPST was associated with a marked increase in composite ischemia (death, myocardial infarction [MI], ischemia-driven revascularization, or new-onset out-of-laboratory stent thrombosis [Academic Research Consortium]) at 48 h and at 30 days (29.2% vs. 4.5% and 31.5% vs. 5.7%, respectively; p < 0.0001 for both). After controlling for potential confounders, IPST remained a strong predictor of all adverse ischemic events at both time points.. In the large-scale CHAMPION PHOENIX trial, the occurrence of IPST was strongly predictive of subsequent adverse cardiovascular events. The potent intravenous adenosine diphosphate antagonist cangrelor substantially reduced IPST, contributing to its beneficial effects at 48 h and 30 days. (Clinical Trial Comparing Cangrelor to Clopidogrel Standard of Care Therapy in Subjects Who Require Percutaneous Coronary Intervention [PCI] [CHAMPION PHOENIX]; NCT01156571).

Topics: Adenosine Monophosphate; Aged; Clopidogrel; Double-Blind Method; Female; Humans; Intraoperative Complications; Male; Middle Aged; Percutaneous Coronary Intervention; Prospective Studies; Standard of Care; Stents; Thrombosis; Ticlopidine; Treatment Outcome

The intensity of antiplatelet therapy during percutaneous coronary intervention (PCI) is an important determinant of PCI-related ischemic complications. Cangrelor is a potent intravenous adenosine diphosphate (ADP)-receptor antagonist that acts rapidly and has quickly reversible effects.. In a double-blind, placebo-controlled trial, we randomly assigned 11,145 patients who were undergoing either urgent or elective PCI and were receiving guideline-recommended therapy to receive a bolus and infusion of cangrelor or to receive a loading dose of 600 mg or 300 mg of clopidogrel. The primary efficacy end point was a composite of death, myocardial infarction, ischemia-driven revascularization, or stent thrombosis at 48 hours after randomization; the key secondary end point was stent thrombosis at 48 hours. The primary safety end point was severe bleeding at 48 hours.. The rate of the primary efficacy end point was 4.7% in the cangrelor group and 5.9% in the clopidogrel group (adjusted odds ratio with cangrelor, 0.78; 95% confidence interval [CI], 0.66 to 0.93; P=0.005). The rate of the primary safety end point was 0.16% in the cangrelor group and 0.11% in the clopidogrel group (odds ratio, 1.50; 95% CI, 0.53 to 4.22; P=0.44). Stent thrombosis developed in 0.8% of the patients in the cangrelor group and in 1.4% in the clopidogrel group (odds ratio, 0.62; 95% CI, 0.43 to 0.90; P=0.01). The rates of adverse events related to the study treatment were low in both groups, though transient dyspnea occurred significantly more frequently with cangrelor than with clopidogrel (1.2% vs. 0.3%). The benefit from cangrelor with respect to the primary end point was consistent across multiple prespecified subgroups.. Cangrelor significantly reduced the rate of ischemic events, including stent thrombosis, during PCI, with no significant increase in severe bleeding. (Funded by the Medicines Company; CHAMPION PHOENIX ClinicalTrials.gov number, NCT01156571.).

Topics: Adenosine Monophosphate; Aged; Angioplasty, Balloon, Coronary; Clopidogrel; Double-Blind Method; Female; Hemorrhage; Humans; Intention to Treat Analysis; Kaplan-Meier Estimate; Male; Middle Aged; Myocardial Ischemia; Platelet Aggregation Inhibitors; Stents; Thrombosis; Ticlopidine

Thienopyridines are among the most widely prescribed medications, but their use can be complicated by the unanticipated need for surgery. Despite increased risk of thrombosis, guidelines recommend discontinuing thienopyridines 5 to 7 days prior to surgery to minimize bleeding.. To evaluate the use of cangrelor, an intravenous, reversible P2Y(12) platelet inhibitor for bridging thienopyridine-treated patients to coronary artery bypass grafting (CABG) surgery.. Prospective, randomized, double-blind, placebo-controlled, multicenter trial, involving 210 patients with an acute coronary syndrome (ACS) or treated with a coronary stent and receiving a thienopyridine awaiting CABG surgery to receive either cangrelor or placebo after an initial open-label, dose-finding phase (n = 11) conducted between January 2009 and April 2011. Interventions Thienopyridines were stopped and patients were administered cangrelor or placebo for at least 48 hours, which was discontinued 1 to 6 hours before CABG surgery.. The primary efficacy end point was platelet reactivity (measured in P2Y(12) reaction units [PRUs]), assessed daily. The main safety end point was excessive CABG surgery-related bleeding.. The dose of cangrelor determined in 10 patients in the open-label stage was 0.75 μg/kg per minute. In the randomized phase, a greater proportion of patients treated with cangrelor had low levels of platelet reactivity throughout the entire treatment period compared with placebo (primary end point, PRU <240; 98.8% (83 of 84) vs 19.0% (16 of 84); relative risk [RR], 5.2 [95% CI, 3.3-8.1] P < .001). Excessive CABG surgery-related bleeding occurred in 11.8% (12 of 102) vs 10.4% (10 of 96) in the cangrelor and placebo groups, respectively (RR, 1.1 [95% CI, 0.5-2.5] P = .763). There were no significant differences in major bleeding prior to CABG surgery, although minor bleeding episodes were numerically higher with cangrelor.. Among patients who discontinue thienopyridine therapy prior to cardiac surgery, the use of cangrelor compared with placebo resulted in a higher rate of maintenance of platelet inhibition.. clinicaltrials.gov Identifier: NCT00767507.

Topics: Acute Coronary Syndrome; Adenosine Monophosphate; Adult; Aged; Aged, 80 and over; Blood Loss, Surgical; Coronary Artery Bypass; Coronary Artery Disease; Double-Blind Method; Female; Humans; Male; Middle Aged; Platelet Activation; Platelet Aggregation Inhibitors; Postoperative Hemorrhage; Purinergic P2Y Receptor Antagonists; Stents; Thienopyridines; Thrombosis

The objective of this study was to investigate the potential synergistic utility of a combination of gaseous nitric oxide (gNO)-intravenous Cangrelor as an effective pharmacological option for the prevention of thrombosis in an animal model of extracorporeal life support (ECLS) circuits.. 10 newborn lambs were placed on ECLS. 5 of them were administered a combination of gNO and intravenous Cangrelor. The remaining 5 were not administered any anticoagulant. The primary end point was duration of ECLS without clot formation. The secondary outcome measure was the absolute maximum transmembrane pressure gradient.. The mean duration of ECLS were 168 min (standard deviation 224.98 min) in the control group and 402 min (standard deviation 287.5 min) in the experimental group (P = 0.17). The peak trans-oxygenator pressure difference was 43 mm Hg (standard deviation 23 mm Hg) in the control group and 62 mm Hg (standard deviation 71 mm Hg) in the experimental group(P = 0.64). Two animals in the experimental group were supported up to 12 h without clot formation. Clot formation in the experimental group occurred after placement of the cannulae but prior to initiation of ECLS flows after cannulation.. A combination of gNO and Cangrelor is prevents clot formation in an experimental animal model when administered through a clean clot-free circuit. However, the combination s ineffective when there are pre-existing clots in the circuit. A bolus of anticoagulation prior to cannulation is needed prior to testing this combination in future studies with a larger sample size.

Topics: Animals; Extracorporeal Membrane Oxygenation; Gases; Nitric Oxide; Sheep; Thrombosis

VA-ECMO is commonly used for patients in cardiogenic shock (CS) or refractory cardiac arrest (CA) undergoing PCI for ACS. In this setting at high risk of both thrombotic and hemorrhagic complications, optimal anti-thrombotic therapy remains ill-defined. We hypothesized that an anti-thrombotic therapy comprising a parenteral anticoagulant (bivalirudin) and a parenteral anti-platelet agent (cangrelor) may prove safe and effective in this scenario. From November 2019 to December 2021, 14 patients received at least one dose of cangrelor (starting dose: 0.125 μg/kg/min) plus bivalirudin, without background aspirin, in the context of PCI and VA-ECMO for ACS-related CS/CA, and were included in this study. Efficacy endpoint was occurrence of thrombotic events and safety endpoint was major bleeding occurrence. Median age was 58 years. The majority (64%) presented with refractory CA. A thrombotic event occurred in 14%, while major bleeding occurred in 21% patients. One patient experienced arterial thrombosis after VA-ECMO arterial cannula removal, another experienced ischemic cerebellar stroke without functional sequelae. Bleeding events were: 29% BARC 3a, 14% BARC 3b, and 7% BARC 5b. Overall in-hospital mortality was 50%. Cangrelor was continued for 5 (4-10) days; temporary discontinuation was necessary in 36%, either for VA-ECMO cannula removal or for bleeding events. A low dose of cangrelor, associated with standard-intensity anticoagulation with bivalirudin was a feasible anti-thrombotic strategy in patients undergoing PCI during VA-ECMO support for ACS-related CS/CA. Bleeding events rates outweighed thrombotic events rates in this critically-ill population, although the observed rates were lowest among available studies.

Topics: Extracorporeal Membrane Oxygenation; Hemorrhage; Humans; Middle Aged; Percutaneous Coronary Intervention; Retrospective Studies; Shock, Cardiogenic; Thrombosis; Treatment Outcome

Patients with refractory cardiogenic shock from an acute myocardial infarction may receive percutaneous coronary intervention (PCI) and require the use of venoarterial extracorporeal membrane oxygenation (VA-ECMO). The purpose of this study was to compare bleeding and thrombotic events in patients treated with cangrelor plus aspirin versus oral dual antiplatelet therapy (DAPT) while supported with VA-ECMO.. We conducted a retrospective review of patients who received PCI, were supported with VA-ECMO, and were treated with either cangrelor plus aspirin or oral DAPT from February 2016 through May 2021 at Allegheny General Hospital. The primary objective was the incidence of major bleeding, defined as Bleeding Academic Research Consortium (BARC) type 3 or greater. The incidence of thrombotic events was a secondary objective.. Thirty-seven patients were included, 19 in the cangrelor plus aspirin group, and 18 in the oral DAPT group. All the patients in the cangrelor group received a dose of 0.75 mcg/kg/min. Major bleeding occurred in 7 patients (36.8%) in the cangrelor group compared to 7 patients (38.9%) in the oral DAPT group (p = 0.90). No patient developed stent thrombosis. Two patients (10.5%) in the cangrelor group had a thrombotic event versus 3 patients (16.7%) in the oral DAPT group (p = 0.66).. Bleeding and thrombotic events were comparable between patients receiving cangrelor plus aspirin versus oral DAPT while on VA-ECMO.

Topics: Aspirin; Drug Therapy, Combination; Extracorporeal Membrane Oxygenation; Hemorrhage; Humans; Percutaneous Coronary Intervention; Platelet Aggregation Inhibitors; Thrombosis; Treatment Outcome

To describe cangrelor use in patients on concurrent mechanical circulatory support who underwent postpercutaneous coronary intervention.. A single-center, retrospective, cohort study.. At a quaternary teaching hospital.. Included patients were ≥18 years old, admitted to the intensive care unit, underwent percutaneous coronary intervention with stent placement, initiated on mechanical circulatory support, and received cangrelor in the postpercutaneous coronary intervention period.. Retrospectively analyzed cangrelor use in patients on mechanical circulatory support.. The primary outcome was the incidence of thrombosis and bleeding events during cangrelor administration. Additional outcomes included initial cangrelor dose, number of cangrelor dose adjustments per patient, survival from mechanical circulatory support, and mortality within 30 days. Overall, 19 patients were included in this study. In total, 14 patients (74%) experienced a bleeding event; however, 93% were classified as a minor bleed. There was 1 major bleeding event. There were no thrombotic events observed during cangrelor administration. The median initial cangrelor dose was 0.5 µg/kg/min. There were 10 patients who underwent dose adjustment, with the majority being dose reductions based on antiplatelet monitoring (VerifyNow assay). Survival from mechanical circulatory support occurred in 17 patients (89%), and 30-day mortality occurred in 8 patients (42%).. For patients receiving cangrelor as a bridge to oral P2Y12 inhibitor therapy on mechanical circulatory support, the authors observed a low rate of major bleeding and no episodes of thrombosis. Lower starting doses appear feasible with no observed increased risk of thrombotic complications. Future studies are needed to confirm these observations.

Topics: Adenosine Monophosphate; Adolescent; Cohort Studies; Hemorrhage; Humans; Percutaneous Coronary Intervention; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Retrospective Studies; Thrombosis; Treatment Outcome

Topics: Adenosine Monophosphate; Anticoagulants; Humans; Infant, Newborn; Percutaneous Coronary Intervention; Platelet Aggregation Inhibitors; Prospective Studies; Purinergic P2Y Receptor Antagonists; Thrombosis; Venous Thromboembolism

Blood platelets' adenosine receptors (AR) are considered to be a new target for the anti-platelet therapy. This idea is based on in vitro studies which show that signaling mediated by these receptors leads to a decreased platelet response to activating stimuli. In vivo evidence for the antithrombotic activity of AR agonists published to date were limited, however, to the usage of relatively high doses given in bolus. The present study was aimed at verifying if these substances used in lower doses in combination with inhibitors of P2Y

Topics: Adenosine Monophosphate; Adenosine-5'-(N-ethylcarboxamide); Adult; Animals; Antithrombins; Blood Pressure; Blood-Brain Barrier; Chlorides; Diastole; Female; Ferric Compounds; Fibrinogen; Humans; Laser-Doppler Flowmetry; Male; Mice, Inbred C57BL; Permeability; Platelet Activation; Platelet Aggregation; Prasugrel Hydrochloride; Purinergic P1 Receptor Agonists; Purinergic P2Y Receptor Antagonists; Systole; Thrombosis

Saponins derived from Panax notoginseng root are widely used as herbal medicines and dietary supplements due to their wide range of health benefits. However, the effects of those from Panax notoginseng flowers (PNF) on platelet function and thrombus formation remain largely unknown. Using a series of platelet function assays, we found that G-Rb2 and G-Rd2, among the ten PNF saponin monomers, significantly inhibited human platelet aggregation and activation induced by adenosine diphosphate (ADP) in vitro. The 50% inhibitory concentration (IC50) of G-Rb2 and G-Rd2 against ADP-induced platelet aggregation was 85.5 ± 4.5 μg mL-1 and 51.4 ± 4.6 μg mL-1, respectively. Mechanistically, G-Rb2 and G-Rd2 could effectively modulate platelet P2Y12-mediated signaling by up-regulating cAMP/PKA signaling and down-regulating PI3K/Akt/Erk1/2 signaling pathways. Co-incubation of the P2Y12 antagonist cangrelor with either G-Rb2 or G-Rd2 did not show significant additive inhibitory effects. G-Rb2 and G-Rd2 also substantially suppressed thrombus growth in a FeCl3-induced murine arteriole thrombosis model in vivo. Interestingly, G-Rd2 generally exhibited more potent inhibitory effects on platelet function and thrombus formation than G-Rb2. Thus, our data suggest that PNF-derived G-Rb2 and G-Rd2 effectively attenuate platelet hyperactivity through modulating signaling pathways downstream of P2Y12, which indicates G-Rb2 and G-Rd2 may play important preventive roles in thrombotic diseases.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Animals; Blood Platelets; Flowers; Ginsenosides; Humans; Mice; Mice, Inbred C57BL; Panax notoginseng; Phosphatidylinositol 3-Kinases; Plants, Medicinal; Platelet Aggregation; Platelet Aggregation Inhibitors; Proto-Oncogene Proteins c-akt; Saponins; Signal Transduction; Thrombosis

Microfluidic flow chambers (MFCs) allow the study of platelet adhesion and thrombus formation under flow, which may be influenced by several variables. We developed a new MFC, with which we tested the effects of different variables on the results of platelet deposition and thrombus formation on a collagen-coated surface.. Whole blood was perfused in the MFC over collagen Type I for 4 min at different wall shear rates (WSR) and different concentrations of collagen-coating solutions, keeping blood samples at room temperature or 37 °C before starting the experiments. In addition, we tested the effects of the antiplatelet agent acetylsalicylic acid (ASA) (antagonist of cyclooxygenase-1, 100 µM) and cangrelor (antagonist of P2Y. Platelet deposition on collagen (I) was not affected by the storage temperature of the blood before perfusion (room temperature vs. 37 °C); (II) was dependent on a shear rate in the range between 300/s and 1700/s; and (III) was influenced by the collagen concentration used to coat the microchannels up to a value of 10 µg/mL. ASA and cangrelor did not cause statistically significant inhibition of platelet accumulation, except for ASA at low collagen concentrations.. Platelet deposition on collagen-coated surfaces is a shear-dependent process, not influenced by the collagen concentration beyond a value of 10 µg/mL. However, the inhibitory effect of antiplatelet drugs is better observed using low concentrations of collagen.

Topics: Adenosine Monophosphate; Aspirin; Blood Platelets; Collagen; Cyclooxygenase Inhibitors; Humans; Male; Microfluidics; Platelet Adhesiveness; Platelet Aggregation; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Thrombosis; Young Adult

Dual antiplatelet therapy (DAPT) remains the cornerstone management for the prevention of acute stent thrombosis after percutaneous intervention (PCI). Situations mandating early interruption of DAPT carry a high risk of ischemic complications. Perioperative bridge therapy using Cangrelor, an intravenous P2Y2 inhibitor, may offer a potential solution. Unfortunately, evidence for its use in non-cardiac procedures is limited.. Our protocol demonstrates successful off-label use of IV Cangrelor bridge therapy in a non-cardiac surgery patient. We describe a case of a 77-year old male; triple therapy with Aspirin, Apixaban, and Ticagrelor for recent drug-eluting stent placement required immediate surgical resection of stage I colonic adenocarcinoma.. Cangrelor bridge therapy was utilized both preoperatively and postoperatively without ischemic or bleeding complications. The patient tolerated exploratory laparoscopic colectomy with minimal bleeding and good post-op recovery.. Minimizing the interruption of DAPT therapy in high-risk patients is achievable. However, careful planning with a team-based approach involving surgeons, cardiologists and pharmacists, along with close clinical follow-up and vigilant management of anti-platelet therapy is recommended.

Topics: Adenosine Monophosphate; Aged; Aspirin; Colectomy; Colonic Neoplasms; Drug-Eluting Stents; Factor Xa Inhibitors; Humans; Male; Percutaneous Coronary Intervention; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Pyrazoles; Pyridones; Thrombosis; Ticagrelor

Large inter-individual variation in platelet response to endogenous agonists and pharmacological agents, including resistance to antiplatelet therapy, prompts a search for novel platelet inhibitors and development new antithrombotic strategies. The present in vitro study evaluates the beneficial effects of three adenosine receptor (AR) agonists (regadenoson, LUF 5835 and NECA), different in terms of their selectivity for platelet adenosine receptors, when used alone and in combination with P2Y

Topics: Adenosine Monophosphate; Drug Resistance; Female; Humans; Male; Platelet Aggregation; Platelet Aggregation Inhibitors; Prasugrel Hydrochloride; Purinergic P1 Receptor Agonists; Receptors, Purinergic P2Y12; Thrombosis

Although used routinely to reduce thrombotic events in patients with coronary disease, the effects of P2Y

Topics: Adenosine Monophosphate; Aged; Aspirin; Blood Platelets; Clopidogrel; Coronary Artery Disease; Female; Fibrin Clot Lysis Time; Fibrinolysis; Humans; Male; Middle Aged; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Thrombosis; Ticagrelor

Topics: Adenosine Monophosphate; Aged; Angioplasty, Balloon, Coronary; Coronary Artery Disease; Female; Fibrinolytic Agents; Humans; Platelet Aggregation Inhibitors; Stents; Thrombosis; Treatment Outcome

Topics: Adenosine Monophosphate; Atherectomy, Coronary; Humans; Percutaneous Coronary Intervention; Stents; Thrombosis

Platelets from patients with diabetes mellitus are hyperactive. Hyperactivated platelets may contribute to cardiovascular complications and inadequate responses to antiplatelet agents in the setting of diabetes mellitus. However, the underlying mechanism of hyperactivated platelets is not completely understood.. We measured P2Y. Platelet P2Y

Topics: Adenosine Monophosphate; Animals; Blood Platelets; Cell Adhesion Molecules; Cell Line; Chlorides; Cyclic AMP; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Disease Models, Animal; Drug Inverse Agonism; Ferric Compounds; Fibrinolytic Agents; Humans; Male; Microfilament Proteins; NF-kappa B; Phosphoproteins; Platelet Aggregation; Platelet Aggregation Inhibitors; Rats; Rats, Wistar; Reactive Oxygen Species; Receptors, Purinergic P2Y12; Thrombosis

The recently published, largest trial with cangrelor, the Cangrelor versus Standard Therapy to Achieve Optimal Management of Platelet Inhibition (CHAMPION)-PHOENIX, suggested that the experimental agent significantly reduced the rate of stent thrombosis (ST) and myocardial infarction (MI) during PCI at 48 hours (h) and 30 days. However, the declared impressive cangrelor vascular non-fatal benefit was contradicted by identical deaths at 48 h, and a trend toward excess mortality at 30 days. We analysed the mismatch between outcomes in the CHAMPION-PHOENIX trial. The trial reported identical mortality (18 death in each arm; odds ratio [OR] 1.00 (0.52-1.92); p>0.999) at 48 h, but more deaths, 60 vs 55, after cangrelor at 30 days. There was a significant reduction of ST from 0.8% (n=46) of the patients in the cangrelor group versus 1.4% (n=74) in the clopidogrel group (odds ratio, 0.62; 95% CI, 0.43 to 0.90; p= 0.01) at 48 h, and a persistent but less impressive ST prevention benefit OR of 0.68 (0.50=0.92, p = 0.01) at 30 days. There were also 48 less MI's following cangrelor usage enforced by a significant difference (odds ratio 0.80 (0.67-0.97) p = 0.02), which was also less prevalent at 30 days (OR 0.82 (0.68-0.98), p = 0.03). The reported ST/MI advantage should result in at least a trend towards numerically less deaths after cangrelor at 30 days follow-up, which was opposite of the results reported in CHAMPION-PHOENIX trial. Efficacy of cangrelor is challenged by the disproportional "reduction" of ST and MI conflicting with identical mortality at 48 h and worsened at day 30 fatalities. The dissociation between vascular mortality and non-fatal vascular ischaemic occlusions, unless compensated by some other unreported cause(s) of death, should be explored and explained. Unadjudicated 30-day outcomes, and all ST types should be fully disclosed. The ongoing FDA cangrelor review should focus on appropriate event count and/or possible mismatch between site-reported and extra adjudicated events in the CHAMPION-PHOENIX trial.

Topics: Adenosine Monophosphate; Blood Platelets; Clopidogrel; Data Interpretation, Statistical; Humans; Myocardial Infarction; Odds Ratio; Percutaneous Coronary Intervention; Platelet Aggregation Inhibitors; Proportional Hazards Models; Randomized Controlled Trials as Topic; Research Design; Stents; Thrombosis; Ticlopidine; Time Factors; Treatment Outcome

Topics: Adenosine Monophosphate; Angioplasty, Balloon, Coronary; Clopidogrel; Female; Humans; Male; Myocardial Ischemia; Platelet Aggregation Inhibitors; Stents; Thrombosis; Ticlopidine

In our previous in vitro study, we reported a constitutively active chimeric P2Y(12) (cP2Y(12)) and found that AR-C78511 is a potent inverse agonist at this receptor. The role of cP2Y(12) in platelet activation and thrombosis is not clear.. To investigate the physiologic implications of cP2Y(12) for platelet activation and thrombus formation, and to evaluate the antiplatelet activity of AR-C78511 as an inverse agonist.. We generated transgenic mice conditionally and platelet-specifically expressing cP2Y(12). High-level expression of cP2Y(12) in platelets increased platelet reactivity, as shown by increased platelet aggregation in response to multiple platelet agonists. Moreover, transgenic mice showed a shortened bleeding time, and more rapid and stable thrombus formation in mesenteric artery injured with FeCl(3). The constitutive activity of cP2Y(12) in platelets was confirmed by decreased platelet cAMP levels and constitutive Akt phosphorylation in the absence of agonists. AR-C78511 reversed the cAMP decrease in transgenic mouse platelets, and exhibited a superior antiplatelet effect to that of AR-C69931MX in transgenic mice.. These findings further emphasize the importance of P2Y(12) in platelet activation, hemostasis, and thrombosis, as well as the prothrombotic role of the constitutive activity of P2Y(12). Our data also validate the in vivo inverse agonist activity of AR-C78511, and confirm its superior antiplatelet activity over neutral antagonists.

Topics: Adenosine Monophosphate; Animals; Bleeding Time; Blood Platelets; Chlorides; Cyclic AMP; Disease Models, Animal; Drug Inverse Agonism; Ferric Compounds; Fibrinolytic Agents; Genotype; Mice; Mice, Transgenic; Phenotype; Phosphorylation; Platelet Activation; Platelet Aggregation; Platelet Aggregation Inhibitors; Proto-Oncogene Proteins c-akt; Purinergic P2Y Receptor Antagonists; Receptors, Purinergic P2Y12; Thrombosis

The addition of phosphodiesterase (PDE) inhibitors has been reported to potentiate the antithrombotic effects of P2Y₁₂ antagonists without increasing bleeding risk. In this study, we report that a potent antiplatelet agent, 2-ethylthio-6-phenethylaminoadenosine (BF061), inhibits platelet activation and thrombosis via P2Y₁₂ antagonism and PDE inhibition. We explored the antiplatelet mechanism of BF061 by measuring cAMP, cGMP levels, PDE activity, and the interaction between ADP and P2Y₁₂ using atomic force microscopy. The antithrombotic effect of BF061 was evaluated in mice using intravital microscopy in FeCl₃₋induced mesenteric and laser-induced cremasteric arterial thrombosis models. BF061 robustly inhibited platelet aggregation and ATP release induced by multiple platelet agonists via P2Y₁₂ antagonism and PDE inhibition. Interestingly, despite being structurally similar to BF061, P2Y₁₂ receptor antagonist AR-C69931MX had no effect on human platelet PDE. In FeCl3-induced mesenteric arterial thrombosis model, BF061 effectively prevented thrombus formation similarly to clopidogrel; it also reduced thrombus volume in laser-injured cremaster arteriole model. In contrast, BF061 induced dramatically less bleeding at an antithrombotic dose compared to clopidogrel. In summary, we developed a novel antiplatelet and antithrombotic agent targeting both P2Y₁₂ and PDE. Given the prevalence of combined antiplatelet therapy in clinical practice, an antiplatelet agent bearing dual activities may have therapeutic advantage as a potential antithrombotic drug.

Topics: Adenosine; Adenosine Monophosphate; Animals; Disease Models, Animal; Drug Synergism; Enzyme Inhibitors; Fibrinolytic Agents; Humans; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Phosphoric Diester Hydrolases; Platelet Activation; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Thrombosis

Topics: Acute Coronary Syndrome; Adenosine Monophosphate; Angioplasty, Balloon, Coronary; Blood Platelets; Clopidogrel; Humans; Platelet Aggregation Inhibitors; Purinergic P2 Receptor Antagonists; Randomized Controlled Trials as Topic; Receptors, Purinergic P2; Receptors, Purinergic P2Y12; Thrombosis; Ticlopidine; Treatment Outcome

Topics: Adenosine Monophosphate; Administration, Oral; Angioplasty, Balloon, Coronary; Clopidogrel; Humans; Infusions, Intravenous; Myocardial Infarction; Platelet Aggregation Inhibitors; Stents; Thrombosis; Ticlopidine

Smoking increases the risk of acute arterial thrombosis, including myocardial infarction, likely due to multi-factorial effects on the vasculature. Heightened platelet reactivity may be among the adverse effects of smoke exposure.. To examine the effects of smoke exposure on platelet function in an atherosclerotic environment, Apoe-deficient female mice, maintained on a Western diet, were exposed (4 hrs/d, 5 d/wk) to sidestream cigarette smoke in a whole-body exposure chamber for 12 weeks. A separate group of wild type C57BL/6J mice were also exposed to smoke in an identical fashion.. In comparison to control Apoe-/- mice exposed to filtered ambient air, smoke-exposed Apoe-/- mice displayed a 1.8±0.3 fold enhanced ADP-induced fibrinogen binding ex vivo (P<0.001) and had a shorter time to thrombotic occlusion following ferric chloride injury of the carotid artery (median time to thrombosis of 8 vs. 13 min; P=0.015). Administration of the direct-acting P2Y12 antagonist cangrelor blunted ex vivo fibrinogen binding and attenuated thrombosis (median time 20 min) in Apoe-/- mice exposed to sidestream smoke. The effects of smoke exposure required a proatherosclerotic background, as wild-type C57Bl/6J mice exposed to smoke displayed similar fibrinogen binding and thrombotic occlusion times as did control mice.. Our results demonstrate that exposure to smoke heightens platelet reactivity and thrombosis in Apoe-/- mice and implicate signaling through platelet P2Y12 receptor as a mediator of the adverse consequence of smoke exposure. These results may partially explain the recent observations that smokers derive greater clinical benefit from the P2Y12 antagonist clopidogrel than do non-smokers.

Topics: Adenosine Monophosphate; Animals; Apolipoproteins E; Blood Platelets; Chlorides; Female; Ferric Compounds; Fibrinogen; Gene Deletion; Mice; Mice, Inbred C57BL; Purinergic P2Y Receptor Antagonists; Receptors, Purinergic P2Y12; Thrombosis; Tobacco Smoke Pollution

To determine the antithrombotic effects of SCH 602539, an analog of the selective protease-activated receptor (PAR)-1 antagonist vorapaxar (formerly SCH 530348) currently in advanced clinical development, and the P2Y(12) ADP receptor antagonist cangrelor, alone and in combination.. Multiple platelet activation pathways contribute to thrombosis. The effects of SCH 602539 and cangrelor alone and in combination on cyclic flow reductions were evaluated in a Folts model of thrombosis in cynomolgus monkeys. The effects of these treatments on ex vivo platelet aggregation and coagulation parameters were also monitored. Dose-dependent inhibition of cyclic flow reductions was observed after treatment with SCH 602539 alone and cangrelor alone (P<0.05 versus vehicle for the 2 highest concentrations of each agent). The combination of SCH 602539 and cangrelor was associated with synergistic antithrombotic effects (P<0.05 versus vehicle for all combinations tested). The 2 highest doses of SCH 602539 inhibited platelet aggregation in response to PAR-1-selective high-affinity thrombin receptor agonist peptide by greater than 80% but did not affect platelet aggregation induced by other agonists; also, they did not affect any coagulation parameters.. The combined inhibition of the PAR-1 and the P2Y(12) ADP platelet activation pathways had synergistic antithrombotic and antiplatelet effects. The addition of a PAR-1 antagonist to a P2Y(12) ADP receptor antagonist may provide incremental clinical benefits in patients with atherothrombotic disease, both in short- and long-term settings. These hypotheses need to be tested clinically.

Topics: Adenosine Monophosphate; Animals; Disease Models, Animal; Drug Therapy, Combination; Fibrinolytic Agents; Macaca fascicularis; Platelet Aggregation Inhibitors; Purinergic P2Y Receptor Antagonists; Receptor, PAR-1; Thrombosis

Anti-platelet drugs are used to prevent intra-arterial thrombus formation after rupture of atherosclerotic plaques. Until now, the inhibitory effect of present and future anti-platelet drugs such as aspirin, ADP receptor P2Y(1)/P2Y(12) antagonists and glycoprotein (GP) Ibalpha inhibitors on the interaction of platelets with human plaques is not known. To study those effects we obtained human atherosclerotic plaques by surgical endarterectomy. Plaques induced maximal platelet aggregation in hirudinized platelet-rich plasma (PRP) and blood that was effectively inhibited by aspirin, the P2Y(1) antagonist MRS2179 and the P2Y(12) antagonist AR-C69931MX, but not by GPIbalpha blockade with the mAB 6B4. Inhibition of platelet aggregation by MRS2179 was 74 +/- 37% and 68 +/- 20%, by AR-C69931MX 94 +/- 7% and 80 +/- 6%, and by aspirin 88 +/- 19% and 64 +/- 28%, in PRP and blood, respectively (mean +/- SD; n = 6-12 with plaques from 6 patients). The combination of both ADP receptor antagonists completely inhibited plaque-induced platelet aggregation in hirudinized PRP and blood. Under arterial flow conditions (1,500s(-1)), blockade of platelet GPIbalpha resulted in a strong decrease of plaque-stimulated platelet adhesion/aggregate formation of 77 +/- 5% (mean +/- SD; n = 4). Furthermore, MRS2179, AR-C69931MX and their combination reduced plaque-dependent platelet aggregate formation by 35 +/- 14%, 32 +/- 13% and 58 +/- 12% (mean +/- SD; n = 5), respectively. Aspirin was without significant effect. In conclusion, a GPIbalpha-blocking antibody, as well as P2Y(1) and P2Y(12) receptor antagonists, alone or in combination, reduce in contrast to aspirin human plaque-induced platelet thrombus formation under arterial flow. Although these new anti-platelet agents inhibit platelet thrombus formation after plaque rupture, more efficient platelet blockers are required.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Antibodies, Monoclonal; Aspirin; Atherosclerosis; Blood Coagulation Tests; Blood Platelets; Carotid Stenosis; Dose-Response Relationship, Drug; Hemorheology; Humans; Platelet Aggregation; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIb-IX Complex; Purinergic P2 Receptor Antagonists; Receptors, Purinergic P2; Receptors, Purinergic P2Y1; Receptors, Purinergic P2Y12; Thrombosis; Time Factors; von Willebrand Factor

We sought to evaluate the mechanisms that support the stability of platelet aggregates on a thrombogenic surface exposed to flowing blood.. Activation of the membrane glycoprotein (GP) IIb/IIIa--mediated in part through the P2Y1 and P2Y12 adenosine 5'-diphosphate (ADP) receptors--is necessary for platelet aggregation. Platelets in growing thrombi exhibit cyclic calcium signal, suggesting that sustained activation may be required for thrombus stability.. Blood was perfused over type I collagen fibrils at the wall shear rate of 1,500 s(-1). Three-dimensional visualization of platelet thrombi was obtained in real time with confocal microscopy. The intracytoplasmic Ca2+ concentration ([Ca2+]i) was measured in fluo-3AM-loaded platelets.. The height of platelet thrombi in control blood was 13.5 +/- 3.3 microm after 6 min, and increased to 16.3 +/- 4.5 microm (n = 8) after an additional 6 min. In contrast, the height was reduced to 5.4 +/- 2.2 and 3.3 +/- 1.3 microm, respectively (p < 0.01, n = 8), when the blood used in the second 6-min perfusion contained a P2Y1 (MRS2179) or P2Y12 (AR-C69931MX) inhibitor. The [Ca2+]i of platelets within forming thrombi oscillated between 212 +/- 38 nmol/l and 924 +/- 458 nmol/l, with cycles lasting 4.2 +/- 2.8 s that were inhibited completely by AR-C69931MX and partially by MRS2179. Accordingly, thrombi became unstable upon perfusion of blood containing the Ca2+ channel blocker, lanthanum chloride. Flow cytometric studies demonstrated that AR-C69931MX, MRS2179, and lanthanum chloride reduced monoclonal antibody PAC-1 binding to platelets, indicating a decrease of membrane-expressed activated GP IIb/IIIa.. Continuous P2Y1 and P2Y12 stimulation resulting in cyclic [Ca2+]i oscillations is required for maintaining the activation of GP IIb/IIIa needed for thrombus stability in flowing blood.

Topics: Adenosine Monophosphate; Blood Platelets; Calcium Channel Blockers; Calcium Signaling; Collagen; Humans; In Vitro Techniques; Lanthanum; Platelet Adhesiveness; Platelet Aggregation; Platelet Glycoprotein GPIIb-IIIa Complex; Purinergic P2 Receptor Antagonists; Receptors, Purinergic P2; Thrombosis; Tirofiban; Tyrosine

Reperfusion therapy for myocardial infarction is limited by a significant reocclusion rate and less optimal myocardial tissue perfusion due to excessive platelet accumulation and recruitment at the sites of vascular injury. We assessed the influence of a selective P2Y(12)-receptor antagonist (AR-C69931MX), in conjunction with thrombolytic therapy, on the prevention of platelet aggregation and thrombus formation.. A canine coronary electrolytic injury thrombosis model was used. Tissue-type plasminogen activator (t-PA; 1 mg/kg in phase I, 0.5 mg/kg in phase II in the AR-C69931MX group, and 1 mg/kg in the placebo group in phase I and II) was administered 30 minutes after thrombus formation; either saline or AR-C69931MX (4 micro g x kg(-1) x min(-1)) was given to all animals intravenously 10 minutes before t-PA administration for a total of 2 hours. All animals received heparin (80 U/kg) as an intravenous bolus followed by a continuous infusion of 17 U x kg(-1) x h(-1). Myocardial tissue perfusion was evaluated by use of the colored microsphere technique and real-time myocardial contrast echocardiography. The incidences of reocclusion and cyclic flow variation were significantly decreased in the AR-C69931MX group (P<0.05). Myocardial tissue flow with AR-C69931MX treatment improved significantly at 20 and 120 minutes after reflow, whereas tissue flow with placebo remained at a level similar to that during occlusion (P<0.05).. The adjunctive administration of AR-C69931MX blocked ADP-mediated platelet aggregation and recruitment and prevented platelet-mediated thrombosis, resulting in prolongation of reperfusion time and a decrease in reocclusion and cyclic flow variations. Importantly, myocardial tissue perfusion was significantly improved in the P2Y(12) antagonist group.

Topics: Adenosine Monophosphate; Angioplasty, Balloon, Coronary; Animals; Bleeding Time; Blood Coagulation; Coronary Circulation; Coronary Restenosis; Coronary Stenosis; Disease Models, Animal; Dogs; Drug Combinations; Echocardiography; Female; Heparin; Infusions, Intravenous; Male; Membrane Proteins; Myocardial Infarction; Myocardial Reperfusion; Platelet Aggregation; Platelet Aggregation Inhibitors; Purinergic P2 Receptor Antagonists; Receptors, Purinergic P2; Receptors, Purinergic P2Y12; Thrombosis; Tissue Plasminogen Activator

In vivo, activated platelets contribute to the initiation of thrombin generation through the exposure of phosphatidylserine to form a procoagulant catalytic surface and through platelet-leukocyte interactions, which lead to the exposure of leukocyte tissue factor (TF). On the basis of observations that the platelet P2Y1 and P2Y12 receptors both contribute to thrombosis and thrombin formation in an in vivo model of TF-induced thromboembolism, we further characterized the role of these receptors in thrombin generation.. By using the selective P2 antagonists MRS2179 and AR-C69931MX, the P2Y12 receptor was found to be involved in thrombin-induced exposure of PS on isolated platelets and consequently in TF-induced thrombin formation in platelet-rich plasma. By contrast, the P2Y1 receptor was not involved in phosphatidylserine exposure nor in thrombin generation in platelet-rich plasma. In addition, both receptors were found to contribute to the interactions between platelets and leukocytes mediated by platelet P-selectin exposure, which result in TF exposure at the surface of leukocytes.. Overall, these results point to a differential involvement of the 2 platelet ADP receptors in the generation of thrombin and provide further evidence for the relevance of molecules targeting these receptors as antithrombotic agents.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Animals; Blood Platelets; Disease Models, Animal; Humans; Leukocytes; Male; Membrane Proteins; Mice; Mice, Inbred C57BL; P-Selectin; Peptide Fragments; Phosphatidylserines; Plasma; Purinergic P2 Receptor Antagonists; Receptors, Purinergic P2; Receptors, Purinergic P2Y1; Receptors, Purinergic P2Y12; Thrombin; Thrombosis

ADP plays a central role in regulating platelet function. It induces platelet aggregation via the activation of 2 major ADP receptors, P2Y(1) and P2Y(12). We have investigated the role of P2Y(12) in platelet adhesion and thrombus formation under physiological flow by using blood from a patient with a defect in the gene encoding P2Y(12). Anticoagulated blood from the patient and from healthy volunteers was perfused over collagen-coated coverslips. The patient's thrombi were smaller and consisted of spread platelets overlying platelets that were not spread, whereas control thrombi were large and densely packed. Identical platelet surface coverage, aggregate size, and morphology were found when a P2Y(12) antagonist, N(6)-(2-methylthioethyl)-2-(3,3,3-trifluoropropylthio)-beta,gamma-dichloromethylene ATP (also known as AR-C69931 MX), was added to control blood. The addition of a P2Y(1) antagonist (adenosine-3',5'-diphospate) to control blood resulted in small, but normally structured, thrombi. Thus, the ADP-P2Y(12) interaction is essential for normal thrombus buildup on collagen. The patient's blood also showed reduced platelet adhesion on fibrinogen, which was not due to changes in morphology. Comparable results were found by using control blood with AR-C69931 MX and also with adenosine-3',5'-diphospate. This suggested that P2Y(12) and P2Y(1) were both involved in platelet adhesion on immobilized fibrinogen, thereby revealing it as ADP dependent. This was confirmed by complete inhibition on the addition of creatine phosphate/creatine phosphokinase.

Topics: Adenosine Diphosphate; Adenosine Monophosphate; Aged; Analysis of Variance; Blood Platelets; Humans; Male; Membrane Proteins; Platelet Adhesiveness; Platelet Aggregation Inhibitors; Receptors, Purinergic P2; Receptors, Purinergic P2Y12; Thrombosis

The platelet P2T receptor plays a major role in platelet aggregation, and its antagonists are predicted to have significant therapeutic potential as antithrombotic agents. We have explored analogues of adenosine triphosphate (ATP), which is a weak, nonselective but competitive P2T receptor antagonist. Modification of the polyphosphate side chain to prevent breakdown to the agonist adenosine diphosphate (ADP) and substitution of the adenine moiety to enhance affinity and selectivity for the P2T receptor led to the identification of 10e (AR-C67085MX), having an IC50 of 2.5 nM against ADP-induced aggregation of human platelets. Compound 10e was the first very potent antagonist of the P2T receptor, with a selectivity for that subtype of the P2 receptor family of >1000-fold. Further modification of the structure produced compound 10l (AR-C69931MX) having an IC50 of 0.4 nM. In vivo, at maximally effective antithrombotic doses, there is little prolongation of bleeding time (1.4-fold), which is in marked contrast to the 5-6-fold found with GPIIb/IIIa antagonists.

Topics: Adenosine Monophosphate; Blood Platelets; Humans; Magnetic Resonance Spectroscopy; Membrane Proteins; Molecular Structure; Platelet Aggregation Inhibitors; Purinergic P2 Receptor Antagonists; Receptors, Purinergic P2Y12; Spectrometry, Mass, Fast Atom Bombardment; Thrombosis