ticagrelor and thienopyridine

Topics: Adenosine; Cardiovascular Diseases; Clopidogrel; Coronary Artery Disease; Humans; Piperazines; Platelet Aggregation Inhibitors; Prasugrel Hydrochloride; Pyridines; Thiophenes; Ticagrelor; Ticlopidine; Treatment Outcome

Platelet inhibitors are the mainstay treatment for patients with vascular diseases. The current 'gold standard' antiplatelet agent clopidogrel has several pharmacological and clinical limitations that have prompted the search for more effective platelet antagonists. The candidates include various blockers of the purinergic P2Y12 receptor such as prasugrel, an oral irreversible thienopyridine; two adenosine triphosphate analogues that bind reversibly to the P2Y12 receptor: ticagrelor (oral) and cangrelor (intravenous); elinogrel, a direct-acting reversible P2Y12 receptor inhibitor (the only antiplatelet compound that can be administered both intravenously and orally); BX 667, an orally active and reversible small-molecule P2Y12 receptor antagonist; SCH 530348, SCH 205831, SCH 602539 and E5555, highly selective and orally active antagonists on the protease-activated receptor 1. A number of drugs also hit new targets: terutroban, an oral, selective and specific inhibitor of the thromboxane receptor; ARC1779, a second-generation, nuclease resistant aptamer which inhibits von Willebrand factor-dependent platelet aggregation; ALX-0081, a bivalent humanized nanobody targeting the GPIb binding site of von Willebrand factor and AJW200, an IgG4 monoclonal antibody of von Willebrand factor. The pharmacology and clinical profiles of new platelet antagonists indicate that they provide more consistent, more rapid and more potent platelet inhibition than agents currently used. Whether these potential advantages will translate into clinical advantages will require additional comparisons in properly powered, randomized, controlled trials.

Topics: Adenosine; Adenosine Monophosphate; Benzofurans; Blood Platelets; Carbamates; Clinical Trials as Topic; Clopidogrel; Humans; Lactones; Piperazines; Platelet Aggregation; Platelet Aggregation Inhibitors; Prasugrel Hydrochloride; Pyridines; Receptor, PAR-1; Receptors, Proteinase-Activated; Thiophenes; Ticagrelor; Ticlopidine; von Willebrand Factor

Dual antiplatelet therapy with aspirin and clopidogrel, in conjunction with heparin, is the most common antithrombotic strategy in percutaneous coronary intervention (PCI) used to reduce peri-procedural ischaemic complications. However, there remains significant inter-individual variability in post-treatment platelet inhibition with this current established therapy. This review focuses on recent developments in oral antiplatelet agents used in PCI, which promise to overcome, at least in part, current shortfalls.. Genetic polymorphisms and medication interactions involving CYP3A4 or CYP2C19, patient compliance and higher platelet reactivity in certain subgroups, such as those with diabetes, are important factors contributing to inter-individual variability in post-treatment platelet inhibition. Higher clopidogrel doses have been associated with improved clinical outcomes, especially in those presenting with acute coronary syndrome. Newer agents, namely prasugrel and ticagrelor, have been shown to have greater potency and superior clinical outcomes. However, this comes with a price of increased bleeding complications.. Whereas more potent antiplatelet therapies are associated with improved outcome, balancing the risk of bleeding and peri-procedural ischaemic complications remains a key aspect to consider when choosing among the ever-increasing number of agents available. The role of intravenous glycoprotein IIb/IIIa (GPIIb/IIIa) needs to be re-examined in the current context of such potent oral antiplatelet agents. Further research will hopefully help to determine the preferred antithrombotic strategy in patients undergoing PCI.

Topics: Adenosine; Angioplasty, Balloon, Coronary; Aryl Hydrocarbon Hydroxylases; Aspirin; Clopidogrel; Coronary Artery Disease; Cytochrome P-450 CYP2C19; Cytochrome P-450 CYP3A; Drug Therapy, Combination; Humans; Piperazines; Platelet Aggregation Inhibitors; Polymorphism, Genetic; Prasugrel Hydrochloride; Pyridines; Risk Factors; Thiophenes; Ticagrelor; 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

Ticagrelor loading dose (LD) increases adenosine plasma levels, which might interfere with fractional flow reserve (FFR) assessment because the latter is based on adenosine-induced hyperemia. In a prospective study, consecutive patients who underwent coronary angiography with at least 1 de novo stenosis >50% and <90% in severity amenable to intervention underwent FFR assessment using intravenous adenosine 140 μg/kg/min for 3 minutes. Patients were subsequently randomized to either ticagrelor 180 mg (n = 38) or control thienopyridine (n = 38) (prasugrel 60 mg [n = 28] or clopidogrel 600 mg [n = 10]), followed by a second FFR assessment of the target lesion 2 hours after drug. Pre-drug, steady hyperemia FFR (sFFR, median, first to third quartiles) was 0.82 (0.75 to 0.88) and 0.81 (0.75 to 0.88), p = 0.9, whereas post-drug, 0.82 (0.72 to 0.87) and 0.79 (0.73 to 0.86), p = 0.5, in thienopyridine and ticagrelor-treated patients, respectively. The primary end point of percent relative change in sFFR between pre- and post-drug periods was greater in ticagrelor- than thienopyridine-treated patients, -1.24 (-5.54 to 0.0) versus -0.51 (-3.68 to 3.21), p = 0.03, respectively. Absolute change in sFFR between pre- and post-drug periods was marginally higher in ticagrelor- than thienopyridine-treated patients -0.01 (-0.04 to 0.0) versus -0.005 (-0.03 to 0.02), p = 0.048, respectively. Reclassification of treatment decision at the sFFR ≤ 0.80 cutoff post-drug occurred in 6 (15.8%) versus 5 (13.2%) of ticagrelor- and thienopyridine-treated patients, respectively. In conclusion, after ticagrelor LD, an absolute and relative reduction in sFFR compared with thienopyridine LD is observed. Administration of ticagrelor should be considered as a potential source, albeit minor, of FFR variability.

Topics: Adenosine; Coronary Angiography; Coronary Artery Disease; Dose-Response Relationship, Drug; Electrocardiography; Female; Follow-Up Studies; Fractional Flow Reserve, Myocardial; Humans; Male; Middle Aged; Prospective Studies; Purinergic P2Y Receptor Antagonists; Pyridines; Ticagrelor; Time Factors; Treatment Outcome

According to the Italian National Report on drug use, thienopyridines (ticlopidine, clopidogrel and prasugrel) and ticagrelor represent the most prescribed antiplatelet agents, beside aspirin. The aim of this study was to analyse the safety profile of these drugs using data from spontaneous reporting of suspected adverse reactions (ADRs).. Suspected ADRs for ticlopidine, clopidogrel, prasugrel and ticagrelor, reported on the Italian National Pharmacovigilance Network between January 2009 and December 2016, were included in the analysis. All suspected ADRs were classified by frequency, seriousness, outcome, age and system organ class.. Clopidogrel showed the highest absolute number of suspected ADRs, followed by ticlopidine. However, these data need to be contextualized in view of the differences in marketing authorization dates, prescription rates and a characterization of the relative seriousness of ADRs per each drug. After the correction for prescription rate, ticagrelor showed the highest reporting trend and ticlopidine the lowest. Most ADRs occurred in the elderly, in particular for ticlopidine. Bleeding represents one of the most reported events (ticlopidine 40%, clopidogrel 26%, prasugrel 42%, ticagrelor 30%) and aspirin was the most frequently associated suspected drug. The majority of ADRs had complete recovery and were non-serious, except for ticlopidine (serious ADRs 53%). Prasugrel showed the highest percentage of 'life-threatening' events and 'death'.. Based on the analysis conducted on spontaneous ADRs reporting system in Italy, the safety profile of antiplatelet drugs seems favourable. However, the overall risk-benefit ratio of these drugs needs to be reassessed taking into account the appropriateness of use in particular populations at risk, such as the elderly. Based on this information, we believe that more attention from clinicians and/or an implementation of regulatory measures could be useful for clinical practice.

Topics: Adenosine; Adult; Aged; Aged, 80 and over; Aspirin; Female; Hemorrhage; Humans; Italy; Male; Middle Aged; Pharmacovigilance; Platelet Aggregation Inhibitors; Pyridines; Ticagrelor

Topics: Adenosine; Clinical Trials as Topic; Clopidogrel; Coronary Thrombosis; Cost-Benefit Analysis; Hemorrhage; Humans; Myocardial Infarction; Piperazines; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; Prasugrel Hydrochloride; Prognosis; Purinergic P2 Receptor Antagonists; Pyridines; Risk Assessment; Survival Rate; Thiophenes; Ticagrelor; Ticlopidine; Treatment Outcome

Topics: Adenosine; Algorithms; Aspirin; Clinical Trials as Topic; Clopidogrel; Humans; Perioperative Care; Piperazines; Platelet Aggregation Inhibitors; Platelet Glycoprotein GPIIb-IIIa Complex; Prasugrel Hydrochloride; Pyridines; Risk Factors; Thiophenes; Ticagrelor; Ticlopidine

Ticagrelor (AZD6140), the first reversibly binding oral P2Y(12) receptor antagonist, blocks adenosine diphosphate (ADP)-induced platelet aggregation via a mode of action distinct from that of thienopyridine antiplatelet agents. The latter must be metabolically activated and binds irreversibly to P2Y(12) for the life of the platelet, precluding restoration of hemostatic function without the generation of new platelets. In in vitro studies comparing binding characteristics of ticagrelor and compound 105, a chemical compound indistinguishable from the active metabolite of prasugrel, ticagrelor exhibited 1) an approximately 100-fold higher affinity for P2Y(12) and rapid achievement of equilibrium (vs no equilibrium reached with compound 105) as assessed by radioligand displacement in a receptor filtration binding assay, 2) 48-fold greater potency in a functional receptor assay using recombinant human P2Y(12), and 3) 63-fold greater potency in inhibiting ADP-induced aggregation in washed human platelets. In rat and dog models of thrombosis/hemostasis, there was greater separation between doses that provided antithrombotic effect and those that increased bleeding for ticagrelor compared with clopidogrel and compound 072, a chemical compound indistinguishable from the prasugrel parent compound. The ratio of dose resulting in 3-fold increase in bleeding time to dose resulting in 50% restoration of blood flow in rats was 9.7 for ticagrelor compared with 2.0 for clopidogrel and 1.4 for compound 072. Similar results were observed in dogs. Our findings suggest that reversibility of P2Y(12) binding with ticagrelor may account for the greater separation between antithrombotic effects and increased bleeding compared with the irreversible binding of clopidogrel and prasugrel.

Topics: Adenosine; Animals; CHO Cells; Clopidogrel; Cricetinae; Cricetulus; Disease Models, Animal; Dogs; Hemostasis; Humans; Piperazines; Platelet Aggregation; Platelet Aggregation Inhibitors; Prasugrel Hydrochloride; Purinergic P2 Receptor Antagonists; Pyridines; Rats; Receptors, Purinergic P2; Receptors, Purinergic P2Y12; Thiophenes; Thrombosis; Ticagrelor; Ticlopidine; Transfection