Ticagrelor: from discovery to Phase III clinical trial

Development of a long-acting tablet with ticagrelor high-loaded nanostructured lipid carriers

Ticagrelor (TCG), an antiplatelet agent, has low solubility and permeability; thus, there are many trials to apply the pharmaceutical technology for the enhancement of TCG solubility and permeability. Herein, we have developed the TCG high-loaded nanostructured lipid carrier (HL-NLC) and solidified the HL-NLC to develop the oral tablet. The HL-NLC was successfully fabricated and optimized with a particle size of 164.5 nm, a PDI of 0.199, an encapsulation efficiency of 98.5%, and a drug loading of 16.4%. For the solidification of HL-NLC (S-HL-NLC), the adsorbent was determined based on the physical properties of the S-HL-NLC, such as bulk density, tap density, angle of repose, Hausner ratio, Carr's index, and drug content. Florite R was chosen because of its excellent adsorption capacity, excellent physical properties, and solubility of the powder after manufacturing. Using an S-HL-NLC, the S-HL-NLC tablet with HPMC 4 K was prepared, which is showed a released extent of more than 90% at 24 h. Thus, we have developed the sustained release tablet containing the TCG-loaded HL-NLC. Moreover, the formulations have exhibited no cytotoxicity against Caco-2 cells and improved the cellular uptake of TCG. In pharmacokinetic study, compared with raw TCG, the bioavailability of HL-NLC and S-HL-NLC was increased by 293% and 323%, respectively. In conclusion, we successfully developed the TCG high-loaded NLC tablet, that exhibited a sustained release profile and enhanced oral bioavailability.

Ticagrelor in the management of coronary artery disease

Ticagrelor is a potent and orally active P2Y₁₂ inhibitor. Ticagrelor has been extensively tested in Phase II and Phase III trials in patients with coronary artery disease. The pharmacokinetics and pharmacodynamics of ticagrelor result in more rapid and effective inhibition of platelet activation compared with other P2Y₁₂ inhibitors. This has resulted in a reduction in recurrent major cardiovascular events in initial randomized controls trials comparing ticagrelor with clopidogrel. More recently, clinical trials have investigated the use of ticagrelor in patients with stable coronary artery disease and a high residual risk of coronary thrombotic events. In patients with stable coronary artery disease, the potent antiplatelet effect of ticagrelor is counterbalanced by an increased risk of major bleeding. Further research is ongoing to determine the optimal duration of ticagrelor therapy.

Differential Effects of Ticagrelor With or Without Aspirin on Platelet Reactivity and Coagulation Activation: A Randomized Trial in Healthy Volunteers

Dual antiplatelet therapy (DAPT) is standard in acute coronary heart disease but confers a bleeding risk. To compare the effects of ticagrelor‐monotherapy with ticagrelor‐based DAPT on hemostatic system activation, we conducted a randomized controlled trial in 44 volunteers using a loading‐dose regimen and measured platelet‐aggregometry triggered by adenosine diphosphate (multiple electrode aggregometry (MEA)‐ADP) and arachidonic acid (MEA‐AA), the vasodilator‐stimulated phosphoprotein (VASP), prothrombin fragment 1.2 (f1.2), and d‐Dimer. Ticagrelor‐based DAPT and ticagrelor‐monotherapy significantly decreased MEA‐ADP (Δmean: −51.4 (−56.9; −45.8) and −46.2 (−51.7; −40.7)) and VASP (Δmean: −70.3 (−76.2; −64.4) and −69.6 (−75.5; −63.7)) at 2 hours and over 24 hours. MEA‐AA was reduced significantly by both treatments (Δmean: −72.9 (−80.6; −65.3) and −25.7 (−33.3; −18.0)) at 2 hours, and stronger by ticagrelor‐based DAPT over 24 hours. Both treatments decreased f1.2 (geometric mean ratio (GMR): 0.92 (0.84; 1.01) and 0.88 (0.80; 0.96)) and d‐Dimer (GMR: 0.89 (0.86; 0.92) and 0.91 (0.88; 0.94)) at 2 hours and d‐Dimer over 24 hours. Ticagrelor‐monotherapy and ticagrelor‐based DAPT comparably affect hemostatic system activation.

The genetic basis of antiplatelet and anticoagulant therapy: A pharmacogenetic review of newer antiplatelets (clopidogrel, prasugrel and ticagrelor) and anticoagulants (dabigatran, rivaroxaban, apixaban and edoxaban)

INTRODUCTION

The study of pharmacogenomics presents the possibility of individualised optimisation of drug therapy tailored to each patients' unique physiological traits. Both antiplatelet and anticoagulant drugs play a key role in the management of cardiovascular disease. Despite their importance, there is a substantial volume of literature to suggest marked person-to-person variability in their effect. Areas covered: This article reviews the data available for the genetic cause for this inter-patient variability of antiplatelet and anticoagulant drugs. The genetic basis for traditional antiplatelets (i.e. aspirin) is compared with the newly available antiplatelet medicines (clopidogrel, prasugrel and ticagrelor). Similarly, the pharmacogenetics of warfarin is compared with the newer direct oral anticoagulants (DOACs) in detail. Expert Opinion: We identify strengths and weaknesses in the research thus far; including shortcomings in trial design and a review of newer analytical techniques. The direction of this research and its real-world implications are discussed.

Serum uric acid levels during dual antiplatelet therapy with ticagrelor or clopidogrel: Results from a single-centre study

BACKGROUND AND AIMS

New antithrombotic therapies have significantly improved the outcomes of patients with acute coronary syndrome (ACS), where the introduction of ticagrelor has provided the greatest mortality benefits. However, ticagrelor treatment has been associated with a potential increase in the serum uric acid (SUA) levels, which may influence endothelial dysfunction and prothrombotic status, thereby affecting the risk of acute cardiovascular events in patients requiring dual antiplatelet therapy (DAPT). The present study aimed to compare the impact of antiplatelet agents such as ticagrelor or clopidogrel on SUA levels and their effect on platelet reactivity.

METHODS AND RESULTS

We included patients admitted for ACS or elective percutaneous coronary intervention (PCI) and discharged with ASA (acetylsalicylic acid; 100-160 mg) and clopidogrel (75 mg) or ticagrelor (90 mg twice a day). Chemistry was assessed at admission (baseline) and after a 30-90-day period of DAPT (together with platelet reactivity). The absolute and percentage variations of SUA after DAPT introduction were considered. Multiple-electrode aggregometry was used to assess platelet function. A total of 378 patients were enrolled, with 145 treated with aspirin and clopidogrel (AC) and 233 with aspirin and ticagrelor (AT). The AC patients were older (p = 0.003) and more often showed elective PCI as an indication to DAPT (<0.001); they received chronic therapy with ARB (angiotensin II receptor blocker; p = 0.001), nitrates (p = 0.044), CCB (calcium channel blocker; p = 0.005) and diuretics (p = 0.044). The AT patients displayed a higher percentage of ACS diagnosis (p < 0.001) and received chronic therapy with ACE (angiotensin-converting enzyme) inhibitors (p = 0.001), beta blockers (p = 0.001) and statins (p = 0.013). The AC patients displayed higher platelet reactivity at COL (collagen) test, ASPI test and ADP (adenosine diphosphate) test (p = 0.03, 0.001 and <0.001, respectively) and a higher percentage of HRPR (high residual platelet reactivity) in the ADP test (p = 0.001). No difference was found in the baseline uric acid and creatinine levels between AC and AT patients. At 30-90 days, a significant absolute and percentage increase in the SUA levels was found in AT as compared to AC patients (0.204 mg/dl vs. -0.165 mg/dl, p = 0.034; 6.26% vs. -0.005%, p = 0.018, respectively). Results were not influenced by variations in renal function. At multivariate analysis, in fact, ticagrelor therapy emerged as an independent predictor of increase in the uric acid levels (odds ratio (OR; 95% confidence interval (CI)) = 2.79 (1.66-4.67), p < 0.001). However, the variation in the SUA levels did not affect platelet reactivity or HRPR in both AC and AT patients.

CONCLUSION

An increase in the SUA levels at 30-90 days was observed in patients receiving chronic DAPT with ticagrelor, but not clopidogrel treatment. However, the changes in the SUA levels do not influence platelet aggregation.

Structurally Enabled Discovery of Adenosine A2A Receptor Antagonists

Over the past decade there has been a revolution in the field of G protein-coupled receptor (GPCR) structural biology. Many years of innovative research from different areas have come together to fuel this significant change in the fortunes of this field, which for many years was characterized by the paucity of high-resolution structures. The determination to succeed has been in part due to the recognized importance of these proteins as drug targets, and although the pharmaceutical industry has been focusing on these receptors, it can be justifiably argued and demonstrated that many of the approved and commercially successful GPCR drugs can be significantly improved to increase efficacy and/or reduce undesired side effects. In addition, many validated targets in this class remain to be drugged. It is widely recognized that application of structure-based drug design approaches can help medicinal chemists a long way toward discovering better drugs. The achievement of structural biologists in providing high-resolution insight is beginning to transform drug discovery efforts, and there are a number of GPCR drugs that have been discovered by use of structural information that are in clinical development. This review aims to highlight the key developments that have brought success to GPCR structure resolution efforts and exemplify the practical application of structural information for the discovery of adenosine A_2A receptor antagonists that have potential to treat multiple conditions.

Inter-patient variability of platelet reactivity in patients treated with prasugrel and ticagrelor

The aim of this study was to evaluate the distribution of platelet reactivity values in patients treated with prasugrel and ticagrelor. This prospective observational study enrolled 200 patients treated with prasugrel or ticagrelor. Platelet aggregation was determined by multiple electrode aggregometry after stimulation with adenosine diphosphate (ADP) in the maintenance phase of treatment with prasugrel or ticagrelor. Only 3% of patients in the prasugrel group and 2% of study participants in the ticagrelor group had high on treatment platelet reactivity (HTPR). The majority of patients displayed low on treatment platelet reactivity (LTPR; prasugrel: 69%; ticagrelor: 64%). The pharmacodynamic effect was similar in patients treated with prasugrel and ticagrelor: the median level of ADP-induced platelet aggregation was 15U (interquartile range IQR 9-21U) under prasugrel treatment and 17U (IQR 8-24U) under ticagrelor treatment (p=0.370). In conclusion, our study suggests that there is some degree of variability in ADP-induced platelet aggregation under treatment with prasugrel and ticagrelor.

New highly active antiplatelet agents with dual specificity for platelet P2Y1 and P2Y12 adenosine diphosphate receptors

Currently approved platelet adenosine diphosphate (ADP) receptor antagonists target only the platelet P2Y12 receptor. Moreover, especially in patients with acute coronary syndromes, there is a strong need for rapidly acting and reversible antiplatelet agents in order to minimize the risk of thrombotic events and bleeding complications. In this study, a series of new P(1),P(4)-di(adenosine-5') tetraphosphate (Ap4A) derivatives with modifications in the base and in the tetraphosphate chain were synthesized and evaluated with respect to their effects on platelet aggregation and function of the platelet P2Y1, P2Y12, and P2X1 receptors. The resulting structure-activity relationships were used to design Ap4A analogs which inhibit human platelet aggregation by simultaneously antagonizing both P2Y1 and P2Y12 platelet receptors. Unlike Ap4A, the analogs do not activate platelet P2X1 receptors. Furthermore, the new compounds exhibit fast onset and offset of action and are significantly more stable than Ap4A to degradation in plasma, thus presenting a new promising class of antiplatelet agents.

The net clinical benefit of personalized antiplatelet therapy in patients undergoing percutaneous coronary intervention

In this study we have demonstrated that individualized treatment with ADP-receptor blockers might result in an improved efficacy with an equal safety.

Clinical implications of drug-drug interactions with P2Y12 receptor inhibitors

Polypharmacy in patients undergoing coronary artery stenting or in those presenting with an acute coronary syndrome is common. Nevertheless, the risk of drug-drug interactions in patients treated simultaneously with P2Y12 receptor inhibitors is less well considered in routine clinical practice. Whereas the irreversible P2Y12 receptor inhibitors clopidogrel and prasugrel are prodrugs requiring cytochrome P450 (CYP) enzymes for metabolic activation, such activation is not necessary for the direct-acting reversible P2Y12 receptor inhibitor ticagrelor. Several drugs frequently used in cardiology have been shown to interact with the metabolism of P2Y12 receptor inhibitors in pharmacodynamic studies. Whereas several drug-drug interactions have been described for clopidogrel and ticagrelor, prasugrel seems to have a low potential for drug-drug interactions. The clinical implications of these interactions have raised concern. In general, concomitant administration of P2Y12 receptor antagonists and strong inhibitors or inducers of CYP3A/CYP2C19 should be performed with caution in patients treated with clopidogrel/ticagrelor. Under most circumstances, clinicians have the option of prescribing alternative drugs with less risk of drug-drug interactions when used concomitantly with P2Y12 receptor inhibitors.

High on-treatment platelet reactivity and P2Y12 antagonists in clinical trials

Dual antiplatelet therapy with aspirin and clopidogrel in patients undergoing percutaneous coronary intervention (PCI) and in patients with acute coronary syndromes (ACS) has substantially decreased the rate of cardiovascular events. Within the past decade, the variability in pharmacodynamic response as well as the moderate antiplatelet efficacy of clopidogrel has raised major concerns, since high on-clopidogrel platelet reactivity has consistently been associated with increased risk for ischaemic events in PCI patients. The variability in response could be linked to genetic polymorphisms impacting on activity of cytochrome P450 enzymes as well as clinical and demographic variables, but, taken together, factors identified so far can explain only up to approximately 12% of this variability in adenosine diphosphate-induced platelet aggregation on clopidogrel. Regulatory agencies as well as major cardiac societies suggest the use of other anti-platelet medications or alternative dosing strategies for clopidogrel in patients with reduced effectiveness of clopidogrel. This review will focus on the current status of alternate strategies for more sufficient suppression of high platelet reactivity.

Phenotyping vs. genotyping for prediction of clopidogrel efficacy and safety: the PEGASUS-PCI study

BACKGROUND

Prognostic values of genotyping and phenotyping for assessment of clopidogrel responsiveness have been shown in independent studies.

OBJECTIVES

To compare different assays for prediction of events during long-term follow-up.

METHODS

In this prospective cohort study polymorphisms of CYP2C19*2 and CYP2C19*17 alleles, vasodilator-stimulated phosphoprotein phosphorylation (VASP) assay, multiple electrode aggregometry (MEA), cone and platelet analyser (CPA) and platelet function analyser (PFA-100) were performed in 416 patients undergoing percutaneous coronary intervention. The rates of events were recorded during a 12-month follow-up.

RESULTS

Platelet aggregation by MEA predicted stent thrombosis (2.4%) better (c-index = 0.90; P < 0.001; sensitivity = 90%; specificity = 83%) than the VASP assay, CPA or PFA-100 (c-index < 0.70; P > 0.05; sensitivity < 70%; specificity < 70% for all) or even the CYP2C19*2 polymorphism (c-index < 0.56; P > 0.05; sensitivity = 30%; specificity = 71%). Survival analysis indicated that patients classified as poor responders by MEA had a substantially higher risk of developing stent thrombosis or MACE than clopidogrel responders (12.5% vs. 0.3%, P < 0.001, and 18.5% vs. 11.3%, P = 0.022, respectively), whereas poor metabolizers (CYP2C19*1/*2 or *2/*2 carriers) were not at increased risks (stent thrombosis, 2.7% vs. 2.5%, P > 0.05; MACE, 13.5% vs. 12.1%, P = 0.556). The incidence of major bleedings (2.6%) was numerically higher in patients with an enhanced vs. poor response to clopidogrel assessed by MEA (4% vs. 0%) or in ultra-metabolizers vs. regular metabolizers (CYP2C19*17/*17 vs. CYP2C19*1/*1; 9.5% vs. 2%). The classification tree analysis demonstrated that acute coronary syndrome at hospitalization and diabetes mellitus were the best discriminators for clopidogrel responder status.

CONCLUSIONS

 Phenotyping of platelet response to clopidogrel was a better predictor of stent thrombosis than genotyping.