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

Platelet-derived circFAM13B associated with anti-platelet responsiveness of ticagrelor in patients with acute coronary syndrome

BACKGROUND

Platelet is enriched with Circular RNAs (circRNAs), with circFAM13B rank among the 10 most abundant circRNAs in platelets. The aim of the present study was to evaluate the predictive value of platelet-derived circFAM13B for the antiplatelet responsiveness and efficacy of ticagrelor in patients with acute coronary syndrome (ACS).

METHODS

Consecutive ACS patients treated with ticagrelor were enrolled, and the antiplatelet responsiveness of 3 days of ticagrelor maintenance treatment was assessed by measuring the adenosine diphosphate (ADP)-induced platelet inhibition rate (ADP%) using thromboelastography. The expression of circFAM13B in the patients' platelets was analyzed by quantitative real-time polymerase chain reaction. The correlation between circFAM13B expression and ticagrelor antiplatelet responsiveness, as well as the independent contribution of circFAM13B to the composite of adverse ischemic events during a follow-up period of at least 12 months was evaluated.

RESULTS

A total of 129 eligible ACS patients treated with ticagrelor were enrolled in the study. A negative correlation was found between the expression of circFAM13B and the ADP% value (r = -0.41, P < 0.001). Patients with ADP% ≥ 76% had a significantly lower level of circFAM13B compared to those with ADP% < 76% (adjusted P = 0.009). Receiver operating characteristic curve analysis demonstrated that combining circFAM13B expression > 1.05 with clinical risk factors could effectively predict the risk of adverse ischemic events (AUC = 0.81, 95% CI: 0.69 to 0.92, P < 0.001). Kaplan-Meier survival analysis showed that patients with circFAM13B > 1.05 had a significantly higher risk of adverse ischemic events compared to those with circFAM13B ≤ 1.05 (P = 0.003). Multivariate logistic hazard analysis identified circFAM13B > 1.05 as an independent risk factor for adverse ischemic events in in ticagrelor-treated ACS patients (adjusted OR: 5.60, 95% CI: 1.69-18.50; P = 0.005).

CONCLUSIONS

Platelet-derived circFAM13B could be utilized for predicting the antiplatelet responsiveness and efficacy of ticagrelor in patients with ACS.

Review of the Ticagrelor Trials Evidence Base

Ticagrelor is a platelet P2Y12 receptor inhibitor approved for use in patients with acute coronary syndromes, coronary artery disease, and low-moderate risk acute ischemic stroke or high-risk transient ischemic attack. Clinical trials have evaluated the efficacy and safety of ticagrelor on ischemic and bleeding outcomes for different indications and with varying treatment approaches. As a result, there is a large body of clinical evidence demonstrating different degrees of net clinical benefit compared with other platelet inhibitor drugs based on indication, patient characteristics, clinical presentation, treatment duration, and other factors. We provide a review of the major trials of ticagrelor in the context of other randomized trials of clopidogrel and prasugrel to organize the volume of available information, elevate corroborating and conflicting data, and identify potential gaps as areas for further exploration of optimal antiplatelet treatment.

Influence of Genetic and Epigenetic Factors of P2Y12 Receptor on the Safety and Efficacy of Antiplatelet Drugs

PURPOSE

P2Y12 receptor inhibitors are drugs that decrease the risk of stent thrombosis and lower the long-term risk of non-stent-related myocardial infarction and stroke. They inhibit the binding of adenosine diphosphate (ADP) to the P2Y12 receptor and effectively reduce platelet reactivity. However, considerable variability in the pharmacodynamics response contributes to a failure of antiplatelet therapy; this phenomenon is especially notorious for older drugs, such as clopidogrel. Some genetic polymorphisms associated with these drugs' metabolic pathway, especially in the CYP2C19 gene, can significantly decrease antiplatelet efficacy. There are few reports on the variability stemming from the target of this drug class that is the P2Y12 receptor itself.

RESULTS AND CONCLUSION

This review summarizes the results of research that focus on the influence of P2Y12 genetic polymorphisms on the pharmacodynamics and the efficacy of P2Y12 inhibitors. We found that the conclusions of the studies are unequivocal, and despite several strong candidates, such as G52T (rs6809699) or T744C (rs2046934), they may not be independent predictors of the inadequate response to the drug. Most probably, P2Y12 genetic polymorphisms contribute to the effect exerted by other gene variants (such as CYP2C19*2/*3/*17), drug interactions, or patient habits, such as smoking. Also, epigenetic modifications, such as methylation or miRNA levels, may play a role in the efficacy of antiplatelet treatment.

Ticagrelor versus clopidogrel in dual antiplatelet therapy after minor stroke or transient ischemic attack: an updated network meta-analysis

BACKGROUND

Dual antiplatelet therapy (DAPT) with clopidogrel plus aspirin is a well-established practice after a minor stroke or transient ischemic attack (TIA). However, ticagrelor plus aspirin may be an alternative.

AIMS

We systematically searched PubMed, Embase, and Cochrane Central from inception to January 2024. We included randomized controlled trials (RCTs) enrolling adults with acute minor stroke or TIA within 72 hours of the onset of the symptoms.

RESULTS

A total of 8 RCTs were included in our meta-analysis. Ticagrelor plus aspirin (RR, 0.70; 95% CrI 0.52, 0.91) and clopidogrel plus aspirin (RR, 0.79; 95% CrI 0.64, 0.98) were superior to aspirin in preventing stroke recurrence in overall analysis. Excluding studies with dual antiplatelet up to 90 days, ticagrelor plus aspirin was the only strategy that maintained superiority compared with aspirin regarding stroke recurrence (RR, 0.70; 95% CrI 0.51, 0.95) and ischemic stroke (RR, 0.68; 95% CrI 0.47, 0.94). There was no significant difference between treatment groups regarding hemorrhagic stroke, functional disability, and mortality.

CONCLUSIONS

DAPTs were superior to aspirin in preventing recurrence or ischemic stroke. Although no significant difference was observed between DAPTs, ticagrelor plus aspirin may be related to worse major bleeding results, including intracranial bleeding. Ticagrelor plus aspirin is a considerable option for patients after a minor stroke or TIA.

A disproportionality analysis of FDA adverse event reporting system (FAERS) events for ticagrelor

Background

Ticagrelor is a commonly used antiplatelet agent, but due to the stringent criteria for trial population inclusion and the limited sample size, its safety profile has not been fully elucidated.

Method

We utilized OpenVigil 2.1 to query the FDA Adverse Event Reporting System database and retrieved reports by the generic name "ticagrelor" published between 1 October 2010 and 31 March 2023. Adverse drug events (ADEs) were classified and described according to the preferred terms and system organ classes in the Medical Dictionary of Regulatory Activity. Proportional reporting ratio (PRR), reporting odds ratio (ROR) and Bayesian Confidence Propagation Neural Network (BCPNN) were used to detect signals.

Results

The number of ADE reports with ticagrelor as the primary suspect drug was 12,909. The top three ADEs were dyspnea [1824 reports, ROR 7.34, PRR 6.45, information component (IC) 2.68], chest pain (458 reports, ROR 5.43, PRR 5.27, IC 2.39), and vascular stent thrombosis (406 reports, ROR 409.53, PRR 396.68, IC 8.02). The highest ROR, 630.24, was found for "vascular stent occlusion". Cardiac arrest (137 reports, ROR 3.41, PRR 3.39, IC 1.75), atrial fibrillation (99 reports, ROR 2.05, PRR 2.04, IC 1.03), asphyxia (101 reports, ROR 23.60, PRR 23.43, IC 4.51), and rhabdomyolysis (57 reports, ROR 2.75, PRR 2.75, IC 1.45) were suspected new adverse events of ticagrelor.

Conclusion

The FAERS database produced potential signals associated with ticagrelor that have not been recorded in the package inserts, such as cardiac arrest, atrial fibrillation, asphyxia, and rhabdomyolysis. Further clinical surveillance is needed to quantify and validate potential hazards associated with ticagrelor-related adverse events.

Progress in the clinical effects and adverse reactions of ticagrelor

BACKGROUND

Ticagrelor is a novel receptor antagonist that selectively binds to the P2Y12 receptor, thereby inhibiting adenosine diphosphate (ADP)-mediated platelet aggregation. Compared to clopidogrel, ticagrelor has the advantages of a fast onset, potent effects, and a reversible platelet inhibition function, which make this drug clinically suitable for treating acute coronary syndrome (ACS), especially acute ST-segment elevation myocardial infarction (STEMI).

OBJECTIVE

This review was performed to determine the basic characteristics, clinical effects, and adverse reactions of ticagrelor.

METHODS

Relevant trials and reports were obtained from the MEDLINE, Embase, and Cochrane Library databases.

RESULTS

Ticagrelor is rapidly absorbed by the body after oral administration, exhibits inherent activity without requiring metabolic activation, and binds reversibly to the P2Y12 receptor. Ticagrelor has been recommended in ACS treatment guidelines worldwide due to its advantageous pharmacological properties and significant clinical benefits. Ticagrelor inhibits platelet aggregation, inhibits inflammatory response, enhances adenosine function, and has cardioprotective effects. However, ticagrelor also causes adverse reactions such as bleeding tendency, dyspnea, ventricular pause, gout, kidney damage, and thrombotic thrombocytopenic purpura in clinical treatment. Therefore, it is necessary to pay attention to risk assessments when using ticagrelor.

CONCLUSION

Ticagrelor is a promising drug for the effective treatment of ACS. When using ticagrelor, individualized treatment should be provided based on the specific conditions of the patients to avoid serious adverse events.

Ticagrelor Steady-State Trough Concentration in Chinese Patients Undergoing Percutaneous Coronary Intervention

BACKGROUND AND OBJECTIVE: Platelets play a pivotal role in thrombotic events associated with acute coronary syndrome (ACS), making oral antiplatelet therapy a cornerstone in antithrombotic strategies. The dosing regimen for the oral antiplatelet drug ticagrelor warrants evaluation to ensure its appropriateness in clinical practice. Therefore, this study aimed to investigate the real-world clinical application of ticagrelor by determining the optimal therapeutic concentration of ticagrelor in Chinese patients undergoing percutaneous coronary intervention (PCI).

METHODS

We enrolled a cohort of 912 patients who underwent PCI with drug-eluting stent implantation for the treatment of ACS. We measured steady-state plasma drug concentrations using high-performance liquid chromatography-tandem mass spectrometry. The therapeutic drug concentration range at steady state was established on the basis of clinical pharmacodynamic indices, with verification of reliability through concentration-effect analysis and receiver operating characteristic curve assessment.

RESULTS

Analysis of plasma samples from the 912 patients revealed significant variations in the steady-state trough concentration of ticagrelor associated with factors such as gender, age, hypertension, and hyperlipidemia. On the basis of this analysis, the optimal therapeutic range for steady-state trough concentration was determined to be 240.65-335.83 ng/mL. Furthermore, the upper limit values for steady-state concentration were established at 439.97 ng/mL for male patients and 347.06 ng/mL for female patients.

CONCLUSIONS

This study provides robust and reliable insights into the optimal therapeutic steady-state trough concentrations of ticagrelor in Chinese patients with post-percutaneous coronary intervention. These findings have significant implications for guiding the rational use of antiplatelet drugs and facilitating precise drug administration in Chinese patients undergoing percutaneous coronary intervention.

An eco-friendly ultra-performance liquid chromatography-mass spectrometry method for quantification of rivaroxaban and ticagrelor in rat plasma: grapefruit interactions

Aim: An eco-friendly ultra-performance liquid chromatography-tandem mass spectrometry method was developed to study the pharmacokinetics of rivaroxaban and ticagrelor in rat plasma, utilizing moxifloxacin as an internal standard. The food-drug interaction between grapefruit juice and these drugs was also investigated. Methods: Liquid-liquid extraction was used. A nonporous stationary phase Agilent® Poroshell 120EC C18 column was used with methanol: 0.1% aqueous formic acid (95:5 v/v) as a mobile phase. The detection was performed in multiple reaction monitoring mode using positive electrospray ionization. The method's validation was conducted in accordance with US FDA and European Medicines Agency guidelines. Results & conclusion: Grapefruit juice should be ingested with caution in patients treated with antithrombotic medications as it may increase their plasma concentration, inducing bleeding, and requires close clinical monitoring.

The effects of P2Y12 adenosine receptors' inhibitors on central and peripheral chemoreflexes

Introduction: The most common side effect of ticagrelor is dyspnea, which leads to premature withdrawal of this life-saving medication in 6.5% of patients. Increased chemoreceptors' sensitivity was suggested as a possible pathophysiological explanation of this phenomenon; however, the link between oversensitization of peripheral and/or central chemosensory areas and ticagrelor intake has not been conclusively proved. Methods: We measured peripheral chemoreceptors' sensitivity using hypoxic ventilatory response (HVR), central chemoreceptors' sensitivity using hypercapnic hyperoxic ventilatory response (HCVR), and dyspnea severity before and 4 ± 1 weeks following ticagrelor initiation in 11 subjects with chronic coronary syndrome undergoing percutaneous coronary intervention (PCI). The same tests were performed in 11 age-, sex-, and BMI-matched patients treated with clopidogrel. The study is registered at ClinicalTrials.com at NCT05080478. Results: Ticagrelor significantly increased both HVR (0.52 ± 0.46 vs. 0.84 ± 0.69 L min-1 %-1; p < 0.01) and HCVR (1.05 ± 0.64 vs. 1.75 ± 1.04 L min-1 mmHg-1; p < 0.01). The absolute change in HVR correlated with the change in HCVR. Clopidogrel administration did not significantly influence HVR (0.63 ± 0.32 vs. 0.58 ± 0.33 L min-1%-1; p = 0.53) and HCVR (1.22 ± 0.67 vs. 1.2 ± 0.64 L min-1 mmHg-1; p = 0.79). Drug-related dyspnea was reported by three subjects in the ticagrelor group and by none in the clopidogrel group. These patients were characterized by either high baseline HVR and HCVR or excessive increase in HVR following ticagrelor initiation. Discussion: Ticagrelor, contrary to clopidogrel, sensitizes both peripheral and central facets of chemodetection. Two potential mechanisms of ticagrelor-induced dyspnea have been identified: 1) high baseline HVR and HCVR or 2) excessive increase in HVR or HVR and HCVR. Whether other patterns of changes in chemosensitivities play a role in the pathogenesis of this phenomenon needs to be further investigated.

Platelet and Monocyte Activation After Transcatheter Aortic Valve Replacement (POTENT-TAVR): A Mechanistic Randomized Trial of Ticagrelor Versus Clopidogrel

Background

Inflammation and thrombosis are often linked mechanistically and are associated with adverse events after transcatheter aortic valve replacement (TAVR). High residual platelet reactivity (HRPR) is especially common when clopidogrel is used in this setting, but its relevance to immune activation is unknown. We sought to determine whether residual activity at the purinergic receptor P2Y12 (P2Y12) promotes prothrombotic immune activation in the setting of TAVR.

Methods

This was a randomized trial of 60 patients (enrolled July 2015 through December 2018) assigned to clopidogrel (300mg load, 75mg daily) or ticagrelor (180mg load, 90 mg twice daily) before and for 30 days following TAVR. Co-primary endpoints were P2Y12-dependent platelet activity (Platelet Reactivity Units; VerifyNow) and the proportion of inflammatory (cluster of differentiation [CD] 14+/CD16+) monocytes 1 day after TAVR.

Results

Compared to clopidogrel, those randomized to ticagrelor had greater platelet inhibition (median Platelet Reactivity Unit [interquartile range]: (234 [170.0-282.3] vs. 128.5 [86.5-156.5], p < 0.001), but similar inflammatory monocyte proportions (22.2% [18.0%-30.2%] vs. 25.1% [22.1%-31.0%], p = 0.201) 1 day after TAVR. Circulating monocyte-platelet aggregates, soluble CD14 levels, interleukin 6 and 8 levels, and D-dimers were also similar across treatment groups. HRPR was observed in 63% of the clopidogrel arm and was associated with higher inflammatory monocyte proportions. Major bleeding events, pacemaker placement, and mortality did not differ by treatment assignment.

Conclusions

Residual P2Y12 activity after TAVR is common in those treated with clopidogrel but ticagrelor does not significantly alter biomarkers of prothrombotic immune activation. HRPR appears to be an indicator (not a cause) of innate immune activation in this setting.

Ticagrelor inhibits platelet aggregation and reduces inflammatory burden more than clopidogrel in patients with stages 4 or 5 chronic kidney disease

BACKGROUND

No study has compared pharmacologic properties of ticagrelor and clopidogrel in non-dialysis patients with stage 4-5 chronic kidney disease (CKD).

METHODS

We conducted a double-blind RCT to compare effects of ticagrelor and clopidogrel in 48 CKD, with the primary outcome of ADP-induced platelet aggregation (WBPA) after 2 weeks of DAPT. In a parallel arm, we compared effects of 2 weeks of ticagrelor plus aspirin on mean changes in WBPA and markers of thromboinflammation among non-CKD controls (n = 26) with that of CKD in the ticagrelor-arm.

RESULTS

Average age of CKD was 53.7 years, with 62% women, 54% African American, and 42% with stage 5 CKD. Ticagrelor generated statistically lower WBPA values post treatment [median 0 Ω (IQR 0, 2)] vs. clopidogrel [median 0 Ω (IQR 0, 5)] (P = 0.002); percent inhibition of WBPA was greater (87 ± 22% vs. 63 ± 50%; P = 0.04; and plasma IL-6 levels were much lower (8.42 ± 1.73 pg/ml vs. 18.48 ± 26.56 pg/ml; P = 0.04). No differences in mean changes in WBPA between CKD-ticagrelor and control groups were observed. Ticagrelor- DAPT reduced levels of IL-1α and IL-1β in CKD-ticagrelor and control groups, attenuated lowering of TNFα and TRAIL levels in CKD-ticagrelor (vs controls), and had global changes in correlation between various cytokines in a subgroup of CKD-ticagrelor subjects not on statins (n = 10). Peak/trough levels of ticagrelor/metabolite were not different between CKD-ticagrelor and control groups.

CONCLUSIONS

We report significant differences in platelet aggregation and anti-inflammatory properties between ticagrelor- and clopidogrel-based DAPT in non-dialysis people with stage 4-5 CKD. These notable inflammatory responses suggest ticagrelor-based DAPT might lower inflammatory burden of asymptomatic patients with stage 4 or 5 CKD. (clinicaltrials.gov # NCT03649711).

Cangrelor in Patients With Coronary Artery Disease Pretreated With Ticagrelor: The Switching Antiplatelet (SWAP)-5 Study

BACKGROUND

There are no studies specifically designed to rule out a drug-drug interaction (DDI) when cangrelor is used among patients who have been pretreated with ticagrelor.

OBJECTIVES

This study sought to rule out a DDI among cangrelor-treated patients who have been pretreated with ticagrelor.

METHODS

In this prospective, randomized, double-blind, placebo-controlled, crossover, pharmacokinetic (PK) and pharmacodynamic (PD) study, patients with coronary artery disease (N = 20) were pretreated with a 180-mg ticagrelor loading dose and after 1 hour randomized to placebo or cangrelor (bolus and infusion for 2 hours). Patients crossed over after 1 to 4 weeks of washout. PK analysis included ticagrelor plasma levels and its active metabolite. PD assessments included VerifyNow P2Y₁₂ reaction units (PRU), light transmittance aggregometry, vasodilator-stimulated phosphoprotein, and Total Thrombus-Formation Analysis System. PK/PD assessments were performed at 7 time points.

RESULTS

Compared with placebo, adding cangrelor to patients pretreated with ticagrelor resulted in a significant reduction in PRU at 30 minutes and 1 hour after starting infusion. At 2 hours after stopping cangrelor/placebo infusion, PRU were low and similar in both groups (16.9 vs 12.6; mean difference: 4.3; 95% CI: -28.6 to 37.3), meeting the noninferiority primary endpoint (predefined noninferiority margin 45 PRU). Consistent findings were shown with all PD assays. PK tracked PD findings with no differences between groups in plasma levels of ticagrelor and its metabolite.

CONCLUSIONS

Compared with placebo, the use of cangrelor in patients pretreated with ticagrelor results in enhanced platelet inhibition with no differences in PK/PD profiles after discontinuation of drug infusion indicating the absence of a DDI. (PD and PK Profiles of Switching Between Cangrelor and Ticagrelor Following Ticagrelor Pre-treatment [SWAP-5]; NCT04634162).

Antiplatelet efficacy of ticagrelor versus clopidogrel in Mediterranean patients with diabetes mellitus and chronic coronary syndromes: A crossover pharmacodynamic investigation

Introduction

Patients with diabetes mellitus (DM) have augmented platelet reactivity and diminished responsiveness to clopidogrel. Ticagrelor, a more potent P2Y12 inhibitor, is clinically superior to clopidogrel in acute coronary syndromes, although its role in chronic coronary syndromes (CCS) is still the subject of debate. The aim of this investigation was to compare the pharmacodynamic effectiveness of ticagrelor and clopidogrel in Mediterranean DM patients with CCS.

Materials and methods

In this prospective, randomized, crossover study, patients (n = 20) were randomized (1:1) to receive, on top of aspirin therapy, either ticagrelor 180 mg loading dose (LD)/90 mg maintenance dose (MD) b.i.d. or clopidogrel 600 mg LD/75 mg MD o.d. for 1 week in a crossover fashion with a 2–4 week washout period between regimens. Platelet function measurements were performed at 4 timepoints in each period (baseline, 2 h and 24 h after LD, and 1 week), including light transmission aggregometry (LTA, primary endpoint), VASP assay, Multiplate and VerifyNow P2Y12.

Results

The ticagrelor LD achieved greater platelet inhibitory effect than clopidogrel LD, assessed with LTA (20 μM ADP as agonist), at 2 h (34.9 ± 3.9% vs. 63.6 ± 3.9%; p &lt; 0.001) and 24 h (39.4 ± 3.5% vs. 52.3 ± 3.8%; p = 0.014). After 1 week of therapy, platelet reactivity was again significantly inferior with ticagrelor compared to clopidogrel (30.7 ± 3.0% vs. 54.3 ± 3.0%; p &lt; 0.001). The results were consistent with the other platelet function assays employed.

Conclusion

In Mediterranean patients with DM and CCS, ticagrelor provides a more potent antiplatelet effect than clopidogrel after the LD and during the maintenance phase of therapy.

Clinical trial registration

[ClinicalTrials.gov], identifier [NCT02457130].

Ticagrelor-Aspirin Versus Clopidogrel-Aspirin Among CYP2C19 Loss-of-Function Carriers With Minor Stroke or Transient Ischemic Attack in Relation to Renal Function: A Post Hoc Analysis of the CHANCE-2 Trial

BACKGROUND

Evidence on the risk-benefit ratio of dual antiplatelet therapies among patients with stroke and impaired renal function is limited and inconsistent.

OBJECTIVE

To investigate the effect of renal function on the efficacy and safety of ticagrelor-aspirin versus clopidogrel-aspirin treatment.

DESIGN

Post hoc analysis of a multicenter, randomized, double-blind, placebo-controlled trial. (ClinicalTrials.gov: NCT04078737).

SETTING

202 centers in China.

PATIENTS

CYP2C19 loss-of-function allele carriers with minor stroke or transient ischemic attack.

INTERVENTION

Ticagrelor-aspirin and clopidogrel-aspirin.

MEASUREMENTS

Renal function was evaluated by estimated glomerular filtration rate (eGFR) levels. The primary efficacy and safety outcomes were recurrent stroke and severe or moderate bleeding within 90 days, respectively.

RESULTS

Among 6378 patients, 4050 (63.5%) had normal (eGFR ≥90 mL/min/1.73 m²), 2010 (31.5%) had mildly decreased (eGFR 60 to 89 mL/min/1.73 m²), and 318 (5.0%) had moderately to severely decreased (eGFR <60 mL/min/1.73 m²) renal function. The corresponding differences in recurrent stroke between ticagrelor-aspirin and clopidogrel-aspirin for normal, mildly decreased, and moderately to severely decreased renal function was -2.8 percentage points (95% CI, -4.4 to -1.3 percentage points) (hazard ratio [HR], 0.63 [CI, 0.49 to 0.81]), -0.2 percentage point (CI, -2.4 to 2.0 percentage points) (HR, 0.98 [CI, 0.69 to 1.39]), and 3.7 percentage points (CI, -2.3 to 10.1 percentage points) (HR, 1.31 [CI, 0.48 to 3.55]), respectively. Rates of severe or moderate bleeding did not substantially differ by treatment assignments across eGFR categories.

LIMITATION

Renal function was only evaluated by using eGFR, and the proportion of patients with severely decreased renal function was low.

CONCLUSION

Patients with normal, rather than impaired, renal function received greater benefit from ticagrelor-aspirin versus clopidogrel-aspirin.

PRIMARY FUNDING SOURCE

Ministry of Science and Technology of the People's Republic of China.

Aspirin platelet reactivity on platelet function and clinical outcome in minor stroke or transient ischemic attack

OBJECTIVE

Whether aspirin platelet reactivity affects platelet function and clinical outcomes with different antiplatelet therapies in patients with mild stroke or transient ischemic attack (TIA) remains unclear. We conducted a subgroup analysis of the PRINCE trial.

MATERIALS AND METHODS

Patients with mild stroke or TIA were randomized into aspirin+ticagrelor, or aspirin+clopidogrel groups; aspirin reaction units (ARU) were measured at the baseline and after 7 ± 2 days to assess response to treatment. High on-treatment platelet reactivity (HPR) was defined as ≥550 ARU (poor response to aspirin). The platelet functions of ticagrelor and clopidogrel were measured using the VerifyNow P2Y₁₂ assay for P2Y₁₂ reaction units (PRU); HPR to P2Y₁₂ was defined as >208 PRU (poor response to P2Y₁₂). Clinical outcomes included stroke and clinical vascular and bleeding events after 90 days.

RESULTS

Among 628 enrolled patients, 69 (11%) were poor aspirin responders. After 7 ± 2 days, the proportion of poor P2Y₁₂ responders for ticagrelor versus clopidogrel significantly reduced in poor (2.6% versus 27.4%) and good (14.3% versus 29.4%) aspirin responders. There were significant interactions between treatment groups, and between treatment groups and aspirin platelet reactivity for poor P2Y₁₂ responders (P = 0.01). After 90 ± 7 days, there were no significant interactions between treatment groups and aspirin platelet reactivity for new stroke risk (good aspirin responders: 5.5% versus 8.8%, hazard ratio [HR]: 0.61; 95% confidence interval [CI], 0.32 to 1.16; P = 0.13; poor aspirin responders: 8.6% versus 8.8%, HR: 0.97, 95% CI: 0.20-4.81; P = 0.97; P for interaction = 0.60). Major bleeding was less frequent in poor than good aspirin responders (ticagrelor/aspirin: 0.4%/0%; clopidogrel/aspirin: 1.4%/0%).

CONCLUSIONS

In patients with minor stroke or TIA, clopidogrel, and particularly ticagrelor, decreased platelet function in poor versus good aspirin responders. The poor platelet reactivity of aspirin could not sufficiently reduce the risk of recurrent stroke with ticagrelor or clopidogrel; however, HPR (poor aspirin response) may have a protective effect on clinically relevant major bleeding.

Antiplatelet Agents in Acute ST Elevation Myocardial Infarction

Platelet aggregation and thrombus formation represent the basic mechanism for clinical, electrocardiographic, and biomarker changes consistent with acute coronary syndrome. Various oral and intravenous formulations of platelet function inhibitors have been developed to help decrease platelet aggregation due to acute atherosclerotic plaque rupture. In this article, we review the various mechanisms, pharmacokinetics/pharmacodynamics, and the key clinical trials related to the platelet inhibitors that form the basis for current recommendations of their use in the ST elevation myocardial infarction guidelines by the American College of Cardiology/American Heart Association.

P2Y12 inhibitors plus aspirin for acute treatment and secondary prevention in minor stroke and high-risk transient ischemic attack: A systematic review and meta-analysis

BACKGROUND

Aspirin is a cornerstone of preventive treatment for stroke recurrence, but during the last few years the role of dual antiplatelet therapy (DAPT) is much more emerging.

OBJECTIVE

This systematic review aimed to compare early use of P2Y12 inhibitors (clopidogrel/ticagrelor) plus aspirin to aspirin alone for acute treatment and secondary prevention in acute non-cardioembolic minor ischemic stroke or TIA.

METHODS

A systematic search on MEDLINE and EMBASE was performed. Treatment effects were estimated with RRs and 95% CI. We used RevMan 5.4 for data analyses. We assessed methodological quality of selected studies according to Rob2 tools and quality of evidence with GRADE approach.

RESULTS

Four RCTs were included, enrolling 21,459 patients. Compared to aspirin alone, DAPT was superior in reducing stroke recurrence (RR 0.74, 95% CI 0.67-0.82, P <0.00001, absolute risk difference by 2%, NNT 50) and disabling stroke defined as mRS>2 (RR 0.84, 95% CI 0.75-0.95, P = 0.004), with no impact on all causes of mortality (RR 1.30, 95% CI 0.90-1.89, P = 0.16). An increased risk of major bleeding was emerged (RR 2.54, 95% CI 1.65-3.92, P <0.0001, absolute risk difference by 0,4%, NNH 250), in particular with ticagrelor, but there was no correlation between therapy duration and bleeding risk, as appeared from one-month (RR 3.06, 95% CI 1.64 to 5.69) and three-month (RR 2.09, 95% CI 1.18 to 3.69) follow-up analysis.

CONCLUSIONS

Early administration of P2Y12 inhibitors plus aspirin in patients with acute non-cardioembolic minor ischemic stroke or TIA reduced the incidence of ischemic stroke recurrence, impacting more significantly than the increased bleeding risk and influencing patients' quality of life by reducing disabling stroke.

Ticagrelor for patients undergoing coronary artery bypass grafting: A meta-analysis of randomized controlled trials

OBJECTIVE

Ticagrelor may be an alternative to aspirin as it provides robust and consistent platelet inhibition. However, the effect of ticagrelor treatment in patients undergoing coronary artery bypass grafting (CABG) has not been well confirmed. We conducted a meta-analysis to appraise whether ticagrelor therapy affects outcomes in CABG patients.

METHODS

We searched PubMed, Embase, EBSCO, and Cochrane databases from its inception up to 4 December 2020 for randomized controlled trials that assessed ticagrelor versus non-ticagrelor in patients undergoing CABG. The primary outcome was the incidence of saphenous vein graft (SVG) occlusion at 1 year after CABG. Secondary outcomes were SVG occlusion at 7 days, major adverse cardiovascular events (MACE), and bleeding requiring reoperation.

RESULTS

Seven trials including 4305 patients (2153 randomized to ticagrelor therapy and 2152 to non-ticagrelor therapy) were included. One-hundred and thirty of 1140 patients (11.4%) randomized to the ticagrelor group versus 175 of 1220 patients (14.3%) randomized to the non-ticagrelor group experienced SVG occlusion at 1 year after CABG. Compared to the control group, ticagrelor therapy yielded a significantly lower risk of SVG occlusion [RR 0.79 (0.64-0.97), p = 0.03]. In the subgroup analysis, ticagrelor plus aspirin compared with aspirin alone did not decrease the risk of SVG occlusion after 1 year [RR 0.65 (0.40-1.07), p = 0.09]. There was no difference in the incidence of SVG occlusion at 7 days [RR 0.67 (0.42-1.06), p = 0.09], MACE up to 1 year [RR 0.99 (0.81-1.21), p = 0.90], or bleeding requiring reoperation [RR 1.16 (0.80-1.70), p = 0.44].

CONCLUSIONS

Compared with non-ticagrelor therapy, ticagrelor decreased the risk of saphenous vein graft occlusion after 1 year in patients undergoing elective CABG with saphenous vein grafting.

Efficacy and safety of perioperative dual antiplatelet therapy with ticagrelor versus clopidogrel in carotid artery stenting

BACKGROUND

Clopidogrel resistance is associated with increased periprocedural neurologic events after carotid artery stenting (CAS). Ticagrelor offers an improved resistance profile; however, its bleeding risk has not been assessed with CAS. Therefore, we examined the efficacy and safety of perioperative dual antiplatelet therapy with aspirin/ticagrelor vs aspirin/clopidogrel in patients undergoing transfemoral carotid artery stenting (tfCAS) or transcarotid artery revascularization (TCAR).

METHODS

We identified all patients who underwent tfCAS or TCAR in the Vascular Quality Initiative registry from January 2016 to March 2021. We stratified patients by procedure and assessed outcomes using 1:3 propensity score-matched cohorts of patients who received perioperative aspirin/ticagrelor vs aspirin/clopidogrel. The primary efficacy outcome was a composite endpoint of in-hospital stroke/death, and the primary safety outcome was access-related bleeding. As a secondary analysis, we assessed these outcomes after stratifying each cohort by intraoperative protamine use.

RESULTS

Among 17,731 tfCAS patients, 593 (3.3%) received aspirin/ticagrelor and 11,404 (64%) received aspirin/clopidogrel. For the 2065 matched patients, no significant differences were found in the composite endpoint of stroke/death (aspirin/ticagrelor, 4.1%; vs aspirin/clopidogrel, 2.6%; relative risk [RR],1.5; 95% confidence interval [CI], 0.88-2.7) or in the individual endpoints of stroke (2.9% vs 1.8%; RR, 1.6; 95% CI, 0.87-3.0) or death (1.7% vs 1.1%; RR, 1.6; 95% CI, 0.71-3.5). However, aspirin/ticagrelor was associated with a higher risk of bleeding (5.8% vs 2.8%; RR, 2.0; 95% CI, 1.2-3.2). In a subgroup analysis of 297 tfCAS patients (14%) who received intraoperative protamine, no differences remained in stroke/death (1.5% vs 3.9%; RR, 0.38; 95% CI, 0.05-3.0), and there was no longer a difference in bleeding (3.0% vs 2.6%; RR, 1.1; 95% CI, 0.24-5.5). Among 17,946 TCAR patients, 453 (2.5%) received aspirin/ticagrelor and 13,696 (76%) received aspirin/clopidogrel. For the 1618 matched patients, no differences were found in stroke/death (0.7% vs 1.4%; RR, 0.53; 95% CI, 0.16-1.8), stroke (0.2% vs 1.2%; RR, 0.20; 95% CI, 0.03-1.5), death (0.5% vs 0.2%; RR, 3.0; 95% CI, 0.42-21), or bleeding (1.2% vs 1.6%; RR, 0.75; 95% CI, 0.28-2.0). For the 1429 TCAR patients (88%) who received protamine, no differences were found in stroke/death (0.8% vs 1.2%; RR, 0.68; 95% CI, 0.20-2.4) or bleeding (0.6% vs 1.4%; RR, 0.39; 95% CI, 0.09-1.7).

CONCLUSIONS

Compared with aspirin/clopidogrel, aspirin/ticagrelor was associated with a potentially lower risk of stroke/death and bleeding complications after CAS in cases in which protamine was used but a higher risk of these outcomes in the absence of protamine. Given our limited sample size, our analysis should be repeated when more patients are available for study. However, our findings suggest that aspirin/ticagrelor could be a reasonable alternative to aspirin/clopidogrel for both tfCAS and TCAR when protamine is used.

Diurnal Variability of Platelet Aggregation in Patients with Myocardial Infarction Treated with Prasugrel and Ticagrelor

Background: Contemporary antiplatelet treatment in acute myocardial infarction (AMI) is based on one of two P2Y12 receptor inhibitors, prasugrel or ticagrelor. The aim of this study was to compare diurnal variability of platelet reactivity between patients receiving prasugrel and ticagrelor during the initial phase of maintenance treatment after AMI. Methods: It was a prospective, two-center, pharmacodynamic, observational study. Blood for platelet testing was sampled at four time points on day four after AMI (8:00, 12:00, 16:00, 20:00). Diurnal variability of platelet reactivity was expressed as a coefficient of variation (CV) of the above-mentioned measurements. Results: 73 invasively-treated patients were enrolled (ticagrelor: n = 47, prasugrel: n = 26). CV was greater in patients treated with ticagrelor compared with prasugrel according to a VASP assay (47.8 [31.6–64.6]% vs. 21.3 [12.9–25.5]%, p < 0.001), while no statistical differences were detected when the CVs of platelet aggregation according to Multiplate were compared between ticagrelor- and prasugrel-treated patients. Ticagrelor-treated patients showed more pronounced platelet inhibition than prasugrel at 16:00 and 20:00 (VASP_16:00: 20.6 ± 15.0 vs. 24.9 ± 12.8 PRI, p = 0.049; VASP_20:00: 18.6 ± 17.7 vs. 26.0 ± 11.7 PRI, p = 0.002). Conclusions: Ticagrelor shows greater diurnal variability in platelet aggregation than prasugrel during the initial maintenance phase of AMI treatment, and this is due to the continuous increase of platelet inhibition after the morning maintenance dose. Both drugs provide an adequate antiplatelet effect early after AMI. Evaluation of the clinical significance of these findings warrants further investigation.

Co-prescription of Dual-Antiplatelet Therapy and Proton Pump Inhibitors: Current Guidelines

Dual-antiplatelet therapy (DAPT) prevents thrombotic complications associated with coronary artery disease, acute coronary syndrome, and stent thrombosis following the percutaneous coronary intervention or coronary artery bypass grafting. When initiating DAPT, the risk of thrombosis must be balanced with the increased risk of upper gastrointestinal bleed (UGIB). Proton-pump inhibitors (PPIs) are concurrently prescribed with DAPT to reduce bleeding risk.

In this review, we discuss the benefits and potential complications of DAPT/PPI co-prescription. The only large international randomized control trial (RCT), Clopidogrel and the Optimization of Gastrointestinal Events Trial (COGENT), shows robust evidence that PPIs are a safe and effective method to reduce the risk of bleeding in patients on DAPT. However, more large-scale RCTs are needed to study potential long-term effects and draw a stronger conclusion on this topic.

Endovascular Treatment of Large Vessel Occlusion Strokes Due to Intracranial Atherosclerotic Disease

Mechanical thrombectomy (MT) has become the gold-standard for patients with acute large vessel occlusion strokes (LVOS). MT is highly effective in the treatment of embolic occlusions; however, underlying intracranial atherosclerotic disease (ICAD) represents a therapeutic challenge, often requiring pharmacological and/or mechanical rescue treatment. Glycoprotein IIb/IIIa inhibitors have been suggested as the best initial approach, if reperfusion can be achieved after thrombectomy, with angioplasty and/or stenting being reserved for the more refractory cases. In this review, we focus on the therapeutic considerations surrounding the endovascular treatment of ICAD-related acute LVOS.

Diabetes and Outcomes Following Personalized Antiplatelet Therapy in Coronary Artery Disease Patients Who Have Undergone PCI

CONTEXT

A personalized antiplatelet therapy guided by a novel platelet function testing (PFT), PL-12, is considered an optimized treatment strategy in stable coronary artery disease (CAD) patients undergoing percutaneous coronary intervention (PCI). However, the safety and efficacy of any dual-antiplatelet therapy (DAPT) strategy may differ in relation to diabetes status.

OBJECTIVE

The aim of this study was to compare the outcomes of PFT-guided personalized DAPT in stable CAD patients with and without diabetes mellitus.

METHODS

The PATH-PCI trial randomly assigned 2285 stable CAD patients to either personalized antiplatelet therapy or standard antiplatelet treatment. We investigated the association and interaction of diabetes on clinical outcomes across 2 treatment groups.

RESULTS

We did not find a significant difference between the personalized group and the standard group in net adverse clinical events in either diabetes patients (10.3% vs 13.4%, P = .224) or in the nondiabetic group (3.1% vs 5.0%, P = .064). In diabetes patients (n = 646, 28.3%), the overall ischemic event rates were significantly low (6.8% vs 11.3%, HR = 0.586, 95% CI, 0.344-0.999, P = .049) and the bleeding event rates did not differ between the 2 groups (3.5% vs 3.3%, HR = 1.066, 95% CI, 0.462-2.458, P = .882). Similarly, in nondiabetic patients, the overall ischemic event rates were significantly low (1.8% vs 4.2%, HR = 0.428, 95% CI, 0.233-0.758, P = .006) and the bleeding event rates did not differ between the 2 groups (1.6% vs 0.9%, HR = 1.802, 95% CI: 0.719-4.516, P = .209).

CONCLUSION

The present study suggests that personalized antiplatelet therapy according to PFT can reduce ischemic events but not increase bleedings in stable CAD patients with or without diabetes who have undergone PCI.

Clopidogrel Versus Ticagrelor for Antiplatelet Therapy in Transcarotid Artery Revascularization (TCAR) in the Society for Vascular Surgery Vascular Quality Initiative

OBJECTIVE

Transcarotid artery revascularization (TCAR) with dynamic flow reversal is a hybrid technique for operative management of carotid artery stenosis. Dual antiplatelet therapy is recommended for patients undergoing TCAR; however, nonresponders to these medications may be predisposed to perioperative thromboembolic complications. Prevalent in up to 44-66% of patients taking clopidogrel, high on-treatment platelet reactivity (HTPR) may thus be responsible for a portion of adverse cerebrovascular events in TCAR. A previous single-institution study has demonstrated the use of ticagrelor as a viable alternative to clopidogrel for antiplatelet therapy in patients undergoing TCAR; however, large-scale comparisons between clopidogrel and ticagrelor are needed to confirm the safety of ticagrelor outside of highly selected patients and providers.

METHODS

Data from patients enrolled in the Society for Vascular Surgery Vascular Quality Initiative undergoing TCAR with a perioperative antiplatelet therapy regimen including either clopidogrel or ticagrelor from January 2015 to March 2021 were analyzed and compared. Multivariable logistic regression and propensity score matching were used to evaluate the primary 30-day outcomes of stroke, major bleeding event, and combined stroke/myocardial infarction (MI)/death rate while adjusting for baseline characteristics of the patients.

RESULTS

A total of 11973 patients underwent TCAR with a dual antiplatelet therapy regimen that included clopidogrel versus 426 patients with ticagrelor. Compared to clopidogrel, patients on ticagrelor were significantly more likely to have coronary artery disease (51% vs 66% [P = <.001]), particularly unstable angina or MI within 6 months (3% vs 9% [P = <.001]), and more likely to have insulin-dependent diabetes mellitus (14% vs 19% [P = <.001]). The unadjusted 30-day rates of stroke, major bleeding, and combined stroke/MI/death were not statistically significant among both groups (1.3% vs 0.5% [P = .14], 2.4% vs 1.4% [P = .18], and 1.9% vs 1.6% [P = .71], respectively). After multivariable adjustment and propensity matching, these remained statistically insignificant.

CONCLUSIONS

Despite a substantially higher medical risk in patients undergoing TCAR with ticagrelor, 30-day rates of stroke, major bleeding events, and combined stroke/MI/death were similar between patients on ticagrelor and clopidogrel as part of adjunctive antiplatelet therapy. Randomized prospective trials, and studies with larger sample sizes and longer follow-up will be needed to better examine the outcome differences in TCAR between these two medications.

Periprocedural Myocardial Injury in High-Risk Patients With NSTEMI Pretreated With Ticagrelor for Less or More Than 6 Hours Before PCI

We assessed the impact on periprocedural myocardial injury of a ticagrelor loading dose given <6 or >6 hours before percutaneous coronary intervention (PCI) in non-ST-elevation myocardial infarction (NSTEMI) patients at high risk. All consecutive patients pretreated with ticagrelor and undergoing PCI for a high-risk NSTEMI have been included in the present analysis. Propensity-score matching was performed to compare the outcomes between patients pretreated with ticagrelor for >6 hours or ≤6 hours. The primary outcome was the rate of periprocedural myocardial injury after PCI. We also recorded clinical outcomes, including major adverse cardiovascular events and major bleedings at 1 month. A total of 1216 patients with NSTEMI were deemed eligible for the study: 481 received a ticagrelor loading dose ≤6 hours (mean time, 4.3 ± 1.2 h) and 735 >6 hours (16.1 ± 8.4 hours) before PCI. Patients pretreated with ticagrelor for >6 hours presented more risk factors and comorbidities compared to others. In patients pretreated with ticagrelor for >6 hours, the rate of periprocedural myocardial injury was significantly lower compared to the other group, in the overall population (19.6% vs 37.8%; P < .0001) and in the matched cohort of 644 patients (18.9% vs 33.5%; P < .0001). The rate of major adverse cardiovascular events and major bleeding events did not differ between the two groups, in both unmatched and matched populations. The present study suggests that ticagrelor pretreatment reduces periprocedural myocardial injury in high-risk patients with NSTEMI undergoing PCI with expected time intervals >6 hours.

Patient characteristics and safety outcomes in new users of ticagrelor and clopidogrel-An observational cohort study in Sweden

PURPOSE

We aimed to describe characteristics of new users of ticagrelor or clopidogrel following a recent coronary event, and to compare incidences of selected safety outcomes.

METHODS

This observational cohort study used data from national Swedish registers. Patients first dispensed ticagrelor or clopidogrel (June 2011-December 2013) were identified from the Prescribed Drug Register and followed until censoring or 31 December 2014. Cohorts were restricted to patients with a recent coronary event-related hospital contact identified in the Patient Register.

RESULTS

The study included 45 987 unique, naïve users of ticagrelor (73% men; mean age 66 years) or clopidogrel (69% men; mean age 69 years). Corresponding to indication, diagnoses before initiation were acute coronary syndrome (93%), myocardial infarction (76%), and percutaneous coronary intervention (69%). The most common medications used in the year before initiation of study therapy were antithrombotic agents (clopidogrel 62%, ticagrelor 43%), mainly low-dose acetylsalicylic acid. Ticagrelor users had a higher incidence (per 1000 person-years) of respiratory bleeding (24.6 [95% confidence interval (CI): 22.1-27.3]; vs clopidogrel users: 14.4 [13.1-15.8]) and dyspnea (25.9 [23.3-28.7]; vs clopidogrel users: 16.8 [15.4-18.4]). Epistaxis accounted for 83-93% of respiratory bleeds. Adjusted analyses found increased risks of gout and acute renal failure with ticagrelor.

CONCLUSIONS

Clopidogrel users were older with a higher prevalence of concomitant medications than ticagrelor users. Our study showed increased incidences of dyspnea and respiratory bleeding (mainly epistaxis) among current ticagrelor users compared with clopidogrel users, and increased risks of gout and acute renal failure after adjustment.

P2Y12 inhibition in acute coronary syndromes treated with percutaneous intervention - Understanding the debate on Prasugrel or Ticagrelor

After more than 10 years of routine clinical use, a debate about the preference of prasugrel over ticagrelor has been unveiled following publication of the ISAR-REACT 5 trial, an investigator-initiated trial directly comparing both substances as part of dual anti-platelet therapy following interventional treatment in patients with acute coronary syndromes (ACS). Both substances had been tested in trials, approved by authorities and subsequently recommended by guidelines according to the strategy applied in the respective approval trial. This resulted in prasugrel tested in TRITON only be given after diagnostic coronary angiography in the absence of ST-segment elevations (NSTE-ACS) and ticagrelor tested in PLATO being administered even before diagnostic coronary angiography in all forms of acute coronary syndromes. Whichever way was safest and most efficient, had never been clarified before. ISAR-REACT 5 showed superior efficacy of prasugrel over ticagrelor in general, and of deferred administration of prasugrel over pre-treatment with ticagrelor in NSTE-ACS patients undergoing percutaneous coronary interventions. Subsequently, in 2020 the European guidelines for NSTE-ACS adopted both positions in recommending the respective preference. Afterwards, a confrontational debate erupted between those favouring the ISAR-REACT 5 results and their implementation in guidelines and others still preferring the generalized interpretation of the overall study results from PLATO. In this review, we reflect the history leading to trial design of TRITON and PLATO and the way this subsequently impacted on clinical practice and guideline recommendations.

Contributions of UDP-Glucuronosyltransferases to Human Hepatic and Intestinal Metabolism of Ticagrelor and Inhibition of UGTs and Cytochrome P450 Enzymes by Ticagrelor and its Glucuronidated Metabolite

Ticagrelor is the first reversibly binding, direct-acting, oral P2Y₁₂ receptor inhibitor. The contribution of UDP-glucuronosyltransferases (UGTs) enzymes to the metabolism of ticagrelor to its glucuronide conjugation, ticagrelor-O-glucuronide, in human liver microsomes (HLM) and human intestinal microsomes (HIM), was well characterized in the current study. The inhibition potential of human major UGTs by ticagrelor and ticagrelor-O-glucuronide was explored. The inhibitory effects of ticagrelor-O-glucuronide on cytochrome P450s (CYPs) enzymes were investigated as well. Ticagrelor glucuronidation exhibits substrate inhibition kinetics in both HLM and HIM with apparent K_m values of 5.65 and 2.52 μM, V_max values of 8.03 and 0.90 pmol min⁻¹·mg protein⁻¹, K_si values of 1,343.0 and 292.9 respectively. The in vitro intrinsic clearances (V_max/K_m) for ticagrelor glucuronidation by HLM and HIM were 1.42 and 0.36 μl min⁻¹·mg protein⁻¹, respectively. Study with recombinant human UGTs suggested that multiple UGT isoforms including UGT1A9, UGT1A7, UGT1A3, UGT1A4, UGT1A1, UGT2B7 and UGT1A8 are involved in the conversion of ticagrelor to ticagrelor-O-glucuronide with UGT1A9 showing highest catalytic activity. The results were further supported by the inhibition studies on ticagrelor glucuronidation with typical UGT inhibitors in pooled HLM and HIM. Little or no inhibition of UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A9 and UGT2B7 by ticagrelor and ticagrelor-O-glucuronide was noted. Ticagrelor-O-glucuronide also exhibited limited inhibitory effects toward CYP2C8, CYP2D6 and CYP3A4. In contrast, ticagrelor-O-glucuronide weakly inhibited CYP2B6, CYP2C9 and CYP2C19 activity with apparent IC₅₀ values of 45.0, 20.0 and 18.8 μM, respectively. The potential of ticagrelor-O-glucuronide to cause drug-drug interactions warrant further study.

Application of Auxiliary VerifyNow Point-of-Care Assays to Assess the Pharmacodynamics of RUC-4, a Novel αIIbβ3 Receptor Antagonist

Introduction  Prehospital therapy of ST-elevation myocardial infarction (STEMI) with αIIbβ3 antagonists improves clinical outcomes, but they are difficult to use in prehospital settings. RUC-4 is a novel αIIbβ3 antagonist being developed for prehospital therapy of STEMI that rapidly achieves high-grade platelet inhibition after subcutaneous administration. Standard light transmission aggregometry (LTA) is difficult to perform during STEMI, so we applied VerifyNow (VN) assays to assess the pharmacodynamics of RUC-4 relative to aspirin and ticagrelor.

Methods  Blood from healthy volunteers was anticoagulated with phenylalanyl-prolyl-arginyl chloromethyl ketone (PPACK) or sodium citrate, treated in vitro with RUC-4, aspirin, and/or ticagrelor, and tested with the VN ADP + PGE ₁ , iso-TRAP, and base channel (high concentration iso-TRAP + PAR-4 agonist) assays. The results were correlated with both ADP (20 µM)-induced LTA and flow cytometry measurement of receptor occupancy and data from individuals treated in vivo with RUC-4.

Results  RUC-4 inhibited all three VN assays, aspirin did not affect the assays, and ticagrelor markedly inhibited the ADP + PGE ₁ assay, slightly inhibited the iso-TRAP assay, and did not inhibit the base channel assay. RUC-4's antiplatelet effects were potentiated in citrate compared with PPACK. Cut-off values were determined to correlate the results of the VN iso-TRAP and base channel assays with 80% inhibition of LTA.

Conclusion  The VN assays can differentiate the early potent anti-αIIbβ3 effects of RUC-4 from delayed effects of P2Y12 antagonists in the presence of aspirin. These pharmacodynamic assays can help guide the clinical development of RUC-4 and potentially be used to monitor RUC-4's effects in clinical practice.

Pharmacokinetics and Pharmacodynamics of Approved and Investigational P2Y12 Receptor Antagonists

Coronary artery disease remains the major cause of mortality worldwide. Antiplatelet drugs such as acetylsalicylic acid and P2Y12 receptor antagonists are cornerstone treatments for the prevention of thrombotic events in patients with coronary artery disease. Clopidogrel has long been the gold standard but has major pharmacological limitations such as a slow onset and long duration of effect, as well as weak platelet inhibition with high inter-individual pharmacokinetic and pharmacodynamic variability. There has been a strong need to develop potent P2Y12 receptor antagonists with more favorable pharmacological properties. Prasugrel and ticagrelor are more potent and have a faster onset of action; however, they have shown an increased bleeding risk compared with clopidogrel. Cangrelor is highly potent and has a very rapid onset and offset of effect; however, its indication is limited to P2Y12 antagonist-naïve patients undergoing percutaneous coronary intervention. Two novel P2Y12 receptor antagonists are currently in clinical development, namely vicagrel and selatogrel. Vicagrel is an analog of clopidogrel with enhanced and more efficient formation of its active metabolite. Selatogrel is characterized by a rapid onset of action following subcutaneous administration and developed for early treatment of a suspected acute myocardial infarction. This review article describes the clinical pharmacology profile of marketed P2Y12 receptor antagonists and those under development focusing on pharmacokinetic, pharmacodynamic, and drug-drug interaction liability.

Hospitalization for Myocardial Infarction with Ticagrelor or Clopidogrel in Patients with Acute Coronary Syndrome: An On-Treatment Comparative Effectiveness Analysis

INTRODUCTION

Prescribing patterns and suboptimal adherence present methodological challenges for real-world head-to-head comparisons of ticagrelor and clopidogrel in intent-to-treat studies. The aim of this study was to compare ticagrelor and clopidogrel in an on-treatment population.

METHODS

This retrospective cohort study used the Optum™ Clinformatics™ database to identify patients with acute coronary syndrome (ACS) discharged on ticagrelor or clopidogrel between January 1, 2012 and September 30, 2019. The primary end point was hospitalization for myocardial infarction (MI); the secondary end point was hospitalization for major bleeding. The ticagrelor and clopidogrel cohorts were balanced by propensity score matching (PSM) 1:3 for demographic and clinical characteristics. Outcomes were ascertained from day 31 until day 365 or end of follow-up.

RESULTS

Of 339,387 patients with ACS, 14,110 ticagrelor- and 57,482 clopidogrel-treated patients met the study criteria. After PSM, 13,373 ticagrelor- and 29,656 clopidogrel-treated patients provided 4945 and 13,895 patient-years of data, respectively, for the primary end point. Hospitalization for MI was significantly lower in the ticagrelor compared to the clopidogrel cohort (2.22 vs. 3.52 per 100 patient-years; 36.8% relative risk reduction [RRR]; P < 0.0001). Hospitalization for major bleeding was similar in the ticagrelor and clopidogrel cohorts (2.04 vs. 2.06 per 100 patient-years; 1.1% RRR, P = 0.9214).

CONCLUSIONS

In this real-world on-treatment analysis, hospitalization for MI was significantly lower with ticagrelor compared to clopidogrel, with similar rates of hospitalization for major bleeding. Study findings underscore the importance of being on the appropriate guideline-recommended therapy and support the use of ticagrelor over clopidogrel.

Inhibitory effect of resveratrol on the pharmacokinetics of ticagrelor in vivo and in vitro

This study was to evaluate the effect of resveratrol on the pharmacokinetics of ticagrelor in rats and the metabolism of ticagrelor in human cytochrome P450 (CYP) 3A4 (CYP3A4) and liver microsomes. Eighteen Sprague-Dawley rats were randomly divided into three groups: group A (control group), group B (50 mg/kg resveratrol), and group C (150 mg/kg resveratrol). After 30 min administration of resveratrol, a single dose of ticagrelor (18 mg/kg) was administered orally. The in vitro experiment was performed to examine the influence of resveratrol on ticagrelor metabolism in CYP3A4*1, human, and rat liver microsomes. Serial biological samples were assayed by validated ultra high-performance liquid chromatography - tandem mass spectrometer methods. For the in vivo study, the area under the concentration-time curve and mean peak plasma concentrations of ticagrelor in group B and C appeared to be significantly higher than the control group, while volume of distribution in terminal phase and apparent clearance of ticagrelor in group B and C were significantly decreased. For the in vitro study, resveratrol exhibited an inhibitory effect on CYP3A4*1, human and rat liver microsomes. The half-maximal inhibitory concentration values of resveratrol were 56.75 μM, 69.07 μM, and 14.22 μM, respectively. Our results indicated that resveratrol had an inhibitory effect on the metabolism of ticagrelor in vitro and in vivo. Further research should focus on the clinical combination of resveratrol with ticagrelor, and ticagrelor plasma concentration should be monitored to avoid the occurrence of adverse reaction.

A review of the effects of ticagrelor on adenosine concentration and its clinical significance

BACKGROUND

Ticagrelor is an oral antiplatelet drug that can reversibly bind to the platelet P2Y12 receptor. Ticagrelor is metabolized mainly by CYP3A4 and produces a rapid blood concentration-dependent platelet inhibitory effect. Unlike other P2Y12 receptor antagonists, many clinical features of ticagrelor are not related to P2Y12 receptor antagonism.

PURPOSE

This review aims to gather existing literature on the clinical effects of ticagrelor after inhibiting adenosine uptake.

METHODOLOGY

The current study reviewed literature related to the effects of ticagrelor on adenosine metabolism. The review also examined the drug's biological effects and clinical characteristics to see how it could be used in a clinical setting.

RESULTS

Many studies have shown that ticagrelor can inhibit equilibrative nucleoside transporter 1 (ENT1). This inhibition leads to intracellular adenosine uptake, increased adenosine half-life and plasma concentration levels and an enhanced adenosine-mediated biological effect.

CONCLUSIONS

Based on the studies reviewed, it was found that ticagrelor essentially inhibits adenosine absorption of adenosine into cells through ENT1, which increases the concentration in the blood and subsequently increases the protection of the heart muscle by adenosine. It also prevents platelet aggregation, and extends the biological effects of coronary arteries. Moreover, it leads to a lower mortality rate in acute coronary syndrome (ACS) patients.

Severe diarrhoea due to use of P2Y12 inhibitor ticagrelor: a rarely reported adverse event

Ticagrelor is a part of dual antiplatelet therapy (DAPT) which has proven benefits in patients with acute coronary syndrome especially in those undergoing percutaneous coronary intervention (PCI). However, like most other drugs, it can lead to undesired and adverse effects such as dyspnoea, easy bruising and gastrointestinal bleeding. We present a case of 70-year-old woman who developed diarrhoea following initiation of DAPT comprising of aspirin and ticagrelor following PCI. After excluding more common causes, it was attributed to ticagrelor administration and completely resolved after it was replaced with another oral antiplatelet agent. On follow-up, the patient reported complete resolution of symptoms.

Ticagrelor resistance: a case series and algorithm for management of non-responders

The placement of cervical and intracranial stents requires the administration of antiplatelet drugs to prevent thromboembolic complications. Ticagrelor has emerged as the most widely used alternative in clopidogrel non-responders owing to its potent antiplatelet effects. Because ticagrelor does not require hepatic activation, many neurointerventionalists choose to forgo laboratory testing of platelet inhibition. In rare instances, patients may not achieve adequate platelet inhibition following ticagrelor administration. In this paper we review the mechanism of action of ticagrelor and its use in cerebrovascular procedures. We present two cases of ticagrelor non-responsiveness from two high-volume cerebrovascular centers, discuss their management, and propose an algorithm for managing ticagrelor non-responsiveness.

Cost-Effectiveness of Ticagrelor Compared with Clopidogrel in Patients with Acute Coronary Syndrome from Vietnamese Healthcare Payers' Perspective

INTRODUCTION

The PLATelet inhibition and patient Outcomes (PLATO) trial (NCT00391872) demonstrated that ticagrelor compared to clopidogrel significantly reduced the rate of death from cardiovascular causes, myocardial infarction or stroke in patients with acute coronary syndrome (ACS). The aim of this study is to analyze the long-term cost-effectiveness of ticagrelor compared to clopidogrel in ACS patients from a Vietnamese healthcare payers' perspective.

METHODS

A two-part cost-effectiveness model was developed to estimate long-term costs and quality-adjusted life-years (QALY). Cardiovascular event rates, hospital bed days, interventions, investigations, study drug utilization and EuroQol 5 Dimension (EQ-5D) data were derived from the PLATO trial. Unit costs of medical services were derived from the Vietnamese governmental price list, and drug costs were based on the weighted average price from the Vietnamese social security report (in VND; 10.000 VND = 0.405 USD). An annual discount rate of 3% was used. Probabilistic and deterministic sensitivity analyses were conducted to evaluate uncertainty of the results.

RESULTS

Ticagrelor was associated with an incremental cost of VND 5.34 million (USD 216.49) and a QALY gain of 0.11. This resulted in a cost per QALY gained of VND 49.58 million (USD 2009.96) from the Vietnamese healthcare payers' perspective. Probabilistic sensitivity analysis indicates that ticagrelor has 59% probability of being cost-effective compared with clopidogrel when using a willingness-to-pay threshold of one gross domestic products (GDP) per capita. Deterministic sensitivity analysis using clinical outcomes from the Asian sub-population of PLATO resulted in a cost per QALY of VND 42.25 million (USD 1712.80).

CONCLUSION

Ticagrelor can be considered a cost-effective treatment for ACS compared with clopidogrel from a Vietnamese healthcare payers' perspective.

Pharmacokinetic Modeling of Morphine's Effect on Plasma Concentrations of Ticagrelor and Its Metabolite in Healthy Volunteers

This study aimed to build a mathematical model describing the pharmacokinetics of ticagrelor and its active metabolite (AR-C124910XX) in a stable setting with concomitant administration of morphine. The model consists of a set of four differential equations prepared upon the available knowledge regarding the biological processes in the pharmacokinetics of ticagrelor. The set of equations was solved numerically using the Runge–Kutta method. The data were obtained in a double-blind, randomized, placebo-controlled, crossover trial. Twenty-four healthy volunteers received a 180-mg ticagrelor loading dose together with either 5-mg morphine or placebo. Blood samples were analyzed with liquid chromatography–tandem mass spectrometry to assess plasma concentrations of ticagrelor and AR-C124910XX before ticagrelor loading dose and after that 1, 2, 3, 4, and 6 h. The model allowed us to reproduce the experimental results accurately and led us to conclusions consistent with clinical observations that morphine delays the time of maximum drug concentration and that the morphine effect occurs due to decreased gastrointestinal motility. Based on the model, we were able to predict the effect of drug dose on receptor blocking efficacy.

P2Y12 Inhibitors Plus Aspirin Versus Aspirin Alone in Patients With Minor Stroke or High-Risk Transient Ischemic Attack

BACKGROUND AND PURPOSE

We performed a systemic review and meta-analysis to elucidate the effectiveness and safety of dual antiplatelet (DAPT) therapy with P2Y12 inhibitors (clopidogrel/ticagrelor) and aspirin versus aspirin monotherapy in patients with mild ischemic stroke or high-risk transient ischemic attack.

METHODS

Following Preferred Reported Items for Systematic Review and Meta-Analysis standards for meta-analyses, Medline, Embase, Cochrane Central Register of Controlled Trials, and the Cochrane Library were searched for randomized controlled trials that included patients with a diagnosis of an acute mild ischemic stroke or high-risk transient ischemic attack, intervention of DAPT therapy with clopidogrel/ticagrelor and aspirin versus aspirin alone from January 2012 to July 2020. The outcomes included subsequent stroke, all-cause mortality, cardiovascular death, hemorrhage (mild, moderate, or severe), and myocardial infarction. A DerSimonian-Laird random-effects model was used to estimate pooled risk ratio (RR) and corresponding 95% CI in R package meta. We assessed the heterogeneity of data across studies with use of the Cochran Q statistic and I² test.

RESULTS

Four eligible trials involving 21 493 participants were included in the meta-analysis. DAPT therapy started within 24 hours of symptom onset reduced the risk of stroke recurrence by 24% (RR, 0.76 [95% CI, 0.68-0.83], I²=0%) but was not associated with a change in all-cause mortality (RR, 1.30 [95% CI, 0.90-1.89], I²=0%), cardiovascular death (RR, 1.34 [95% CI, 0.56-3.17], I²=0%), mild bleeding (RR, 1.25 [95% CI, 0.37-4.29], I²=94%), or myocardial infarction (RR, 1.45 [95% CI, 0.62-3.39], I²=0%). However, DAPT was associated with an increased risk of severe or moderate bleeding (RR, 2.17 [95% CI, 1.16-4.08], I²=41%); further sensitivity tests found that the association was limited to trials with DAPT treatment duration over 21 days (RR, 2.86 [95% CI, 1.75-4.67], I²=0%) or ticagrelor (RR, 2.17 [95% CI, 1.16-4.08], I²=37%) but not within 21 days or clopidogrel.

CONCLUSIONS

In patients with noncardioembolic mild stroke or high-risk transient ischemic attack, DAPT with aspirin and clopidogrel/ticagrelor is more effective than aspirin alone for recurrent stroke prevention with a small absolute increase in the risk of severe or moderate bleeding.

Effects of clopidogrel, prasugrel and ticagrelor on prevention of stent thrombosis in patients underwent percutaneous coronary intervention: A network meta-analysis

Background

Clopidogrel, prasugrel and ticagrelor, acting on platelet P2Y12 receptor, are commonly used for prevention of stent thrombosis (ST) among patients who underwent percutaneous coronary intervention (PCI). This study aimed to compare the effects of these drugs by a systematic review and network meta‐analysis.

Hypothesis

Efficacies of clopidogrel, prasugrel and ticagrelor on preventing ST are not the same.

Methods

PubMed, Embase and Cochrane Library were searched for randomized controlled trials (RCTs) that investigated the effect of clopidogrel, prasugrel, or ticagrelor on prevention of ST in patients who underwent PCI. The efficacies between groups were compared by a Bayesian network meta‐analysis, by which the pooled odds ratios (ORs) and 95% confidence intervals (CIs) was calculated.

Results

Fourteen studies and 46 983 participants were included in this study. The pooled results illustrated that clopidogrel, prasugrel and ticagrelor were effective on prevention of ST. Patients treated with prasugrel (OR = 0.30, 95% CI = 0.052 ~ 0.73, P < 0.05) and ticagrelor (OR = 0.25, 95% CI = 0.035 ~ 0.65, P < 0.05) had lower incidence of ST compared to those treated with clopidogrel. Patients treated with ticagrelor showed similar frequency with those in prasugrel group (OR = 0.86, 95% CI = 0.22 ~ 2.3, P > 0.05). No significant heterogeneity was observed across included studies.

Conclusions

Our findings suggest that prasugrel and ticagrelor are more effective than clopidogrel on prevention of ST among patients underwent PCI. Simultaneously, there is no significant difference in the prevention of ST between prasugrel and ticagrelor.

Temporal Trends of Bleeding Episodes during Half- vs. Standard-Dose Ticagrelor in Acute Coronary Syndrome Patients with Low Platelet Reactivity: A Randomized BLEEDING-ACS Trial

To assess the temporal trends of bleeding episodes during half- vs. standard-dose ticagrelor in acute coronary syndrome (ACS) patients with low platelet reactivity (LPR) during standard-dose ticagrelor (90 mg bid). ACS Patients with LPR (<85 P2Y12 reaction units) (n = 122) were randomly assigned to receive either half-dose (45 mg bid) or standard-dose ticagrelor (90 mg bid). The primary endpoint was incidence of Bleeding Academic Research Consortium (BARC) bleeding at 1 week, 1, 3 and 6 months. Dyspnea and ischemic events were also evaluated. Bleeding episodes were most commonly observed at 1 month and then decreased over time. Half-dose ticagrelor did not reduce any BARC bleeding (odds ratio [OR] 0.900, 95% confidence interval [CI] 0.563-1.440, p = 0.661). However, serious bleeding (BARC type ≥2) occurred less often in half-dose ticagrelor (OR 0.284, 95% CI 0.088-0.921, p = 0.036). The rate of moderate-to-severe dyspnea was highest at 1 month, then decreased over time. Half-dose ticagrelor did not decrease moderate-to-severe dyspnea (Borg scale ≥ 3) (OR 1.066, 95% CI 0.322-3.530, p = 0.916). The risk of ischemic events was also similar between the groups. In conclusions, compared with standard-dose ticagrelor, half-dose ticagrelor reduced serious bleeding events during early period of dual-antiplatelet therapy in ACS patients with LPR; however, the risk of any bleeding events and dyspnea did not differ according to ticagrelor dose. Clinical registration: KCT0004640.

Anti-platelet Drug-loaded Targeted Technologies for the Effective Treatment of Atherothrombosis

Atherothrombosis results from direct interaction between atherosclerotic plaque and arterial thrombosis and is the most common type of cardiovascular disease. As a long term progressive disease, atherosclerosis frequently results in an acute atherothrombotic event through plaque rupture and platelet-rich thrombus formation. The pathophysiology of atherothrombosis involves cholesterol accumulation endothelial dysfunction, dyslipidemia, immuno-inflammatory, and apoptotic aspects. Platelet activation and aggregation is the major cause for stroke because of its roles, including thrombus, contributing to atherosclerotic plaque, and sealing off the bleeding vessel. Platelet aggregates are associated with arterial blood pressure and cardiovascular ischemic events. Under normal physiological conditions, when a blood vessel is damaged, the task of platelets within the circulation is to arrest the blood loss. Antiplatelet inhibits platelet function, thereby decreasing thrombus formation with complementary modes of action to prevent atherothrombosis. In the present scientific scenario, researchers throughout the world are focusing on the development of novel drug delivery systems to enhance patient's compliance. Immediate responding pharmaceutical formulations become an emerging trend in the pharmaceutical industries with better patient compliance. The proposed review provides details related to the molecular pathogenesis of atherothrombosis and recent novel formulation approaches to treat atherothrombosis with particular emphasis on commercial formulation and upcoming technologies.

The effect of ticagrelor on microarterial thrombosis in an experimental model

Thromboses that form in the pedicle after free flap and/or replantation may result in the loss of the flap and/or limb. Ticagrelor is an adenosine diphosphate (ADP) receptor antagonist antithrombotic that can inhibit ADP-dependent platelet activation and aggregation. It is clinically used in acute coronary syndrome and unstable angina. However, its effect on microarterial anastomoses has not been investigated in the literature. An experimental thrombosis model was developed in both femoral arteries of a total of 40 rats. Twenty rats were randomly selected as the drug-free control group, and 20 rats were randomly selected as the ticagrelor group. The rats in the ticagrelor group were administered a 20 mg/kg loading dose orally by gavage 24 h before the experiment, and a maintenance dose of 2x10 mg/kg ticagrelor for 14 days after surgery. After the experiment, the femoral artery was evaluated for macroscopic and microscopic thrombosis, inflammation, edema, and endothelialization. Macroscopically and microscopically, thrombosis was observed at rates of 73.3% and 33.3% in the control group and the ticagrelor group, respectively. Inflammation in the vessel wall was found as 56.7% in the control group and 16.7% in the ticagrelor group. Edema in the vessel wall was found in 63.3% of the control group and 20% of the ticagrelor group. A statistical difference was found between the two groups in terms of thrombosis, inflammation, and edema. Both groups had similar characteristics in terms of endothelialization. Ticagrelor has a reducing effect on thrombosis in the microarterial tuck model.

Combined glycoprotein IIb/IIIa inhibitor therapy with ticagrelor for patients with acute coronary syndrome

This study was to compare the efficacy and safety of combined glycoprotein IIb/IIIa inhibitor (GPI) and ticagrelor versus ticagrelor in patients with acute coronary syndrome (ACS). An observational study was conducted using the Improving Care for Cardiovascular Disease in China-ACS project. Totally, 13,264 patients with ACS and received combination therapy or ticagrelor therapy were analyzed. The primary outcome was the composite of major cardiovascular events (MACE: all-cause mortality, myocardial infarction [MI], stent thrombosis, cardiogenic shock, and ischemic stroke), and secondary outcomes included all-cause mortality, MI, stent thrombosis, cardiogenic shock, and ischemic stroke. The multivariable adjusted analysis indicated that combination therapy was associated with an increased risk of major cardiovascular events (MACE) (P = 0.001), any bleeding (P<0.001), and major bleeding (P = 0.005). Moreover, the multivariable adjusted for propensity score-matched (PSM) analysis suggested that combination therapy produced additional risk of MACE (P = 0.014), any bleeding (P<0.001), and major bleeding (P = 0.005). Moreover, PSM analysis suggested that combination therapy was associated with greater risk of stent thrombosis (P = 0.012) and intracranial bleeding (P = 0.020). Combined GPI and ticagrelor therapies did not have any beneficial effects on MACE, stent thrombosis, intracranial bleeding, any bleeding, or major bleeding.

Pharmacodynamic and clinical efficacy of reduced ticagrelor maintenance doses in patients with coronary artery disease

OBJECTIVE

An increasing body of data indicates that a reduction of ticagrelor maintenance dose (MD) in stabilized patients might improve ticagrelor's safety profile and adherence to the treatment. The aim of this review was to discuss the rationale and summarize the current pharmacodynamic and clinical outcomes-based evidence from reduced MD of ticagrelor in patients with coronary artery disease (CAD).

METHODS

A narrative systematic review based on a literature search using the PubMed database from its inception through to June 2020. A search strategy included a combination of relevant search terms regarding ticagrelor reduced MD. The pre-determined inclusion criteria were: (1) randomized or observational trials; (2) presentation of clinical or pharmacodynamic results; (3) evaluation of any ticagrelor MD below 90 mg BID in patients with CAD.

RESULTS

Studies evaluating the following ticagrelor reduced MD have been identified: 90 mg QD, 60 mg BID, 60 mg QD, 45 mg BID, 22.5 mg BID. Majority of trials assessing doses <60 mg BID were performed in Asian patients only. Antiplatelet effect of ticagrelor in CAD decreases with the dose, however even reduced MDs provide sufficient platelet inhibition, which is greater than in clopidogrel-treated patients. De-escalation of ticagrelor dose shows a propensity towards a reduced rate of bleeding and non-bleeding adverse events.

CONCLUSIONS

Ticagrelor doses below 90 mg BID generally show an acceptable profile of platelet inhibition. The number of studies reporting clinical outcomes in CAD patients receiving reduced MD of ticagrelor are limited, however available results indicate that in a stable setting this strategy offers improved safety with preserved efficacy in the prevention of thrombotic events.

The potency of selatogrel, a reversible antagonist of the P2Y12 receptor, is affected by calcium concentration

Here, we report the in vitro characterization of the P2Y12 receptor antagonist selatogrel (ACT-246475). Binding studies with radiolabeled selatogrel demonstrated that selatogrel is a competitive antagonist of ADP binding to the P2Y12 receptor with a fast onset of action. Consequently, selatogrel was confirmed to be a potent inhibitor of P2Y12-mediated intra-platelet signaling and ADP-induced platelet activation. Characterization of selatogrel in platelet-rich plasma in vitro demonstrated that the mode of anti-coagulation affected the anti-platelet potency. Specifically, in platelet-rich plasma containing physiological calcium concentration (anticoagulated with a direct thrombin inhibitor), selatogrel achieved half-maximal inhibition of ADP-induced platelet aggregation at a 3-fold lower concentration than in conditions with low calcium concentration (anticoagulated with citrate). Furthermore, calcium-dependent reduction in selatogrel potency was observed in whole blood platelet aggregation using the VerifyNow™ system with a 3.7-fold potency loss in low calcium conditions. A comparable potency loss was also observed with the reversible P2Y12 receptor antagonists ticagrelor, cangrelor and elinogrel. Furthermore, receptor-binding experiments using radiolabeled selatogrel confirmed a 3-fold lowering of selatogrel binding affinity to the P2Y12 receptor in low calcium conditions. In conclusion, our data suggest that in low calcium conditions (i.e., citrate-anticoagulated blood), there is a risk of underestimating the potency of reversible P2Y12 receptor antagonists. To avoid overdosing, and a potential increase in bleeding risk, we propose that the ex vivo evaluation of reversible P2Y12 receptor antagonists should be performed with platelet assay systems containing physiological calcium concentration.

Antiplatelet effect of ticagrelor with aspirin in acute minor stroke and transient ischemic attack stratified by CYP2C19 metabolizer status: subgroup analysis of the PRINCE trial

Studies on antiplatelet effect of ticagrelor/aspirin and clopidogrel/aspirin in patients with acute minor stroke and transient ischemic attack (TIA) stratified by CYP2C19 metabolizer status is limited. We gained data from the Platelet Reactivity In Non-disabling Cerebrovascular Events study. Platelet reactivity was tested at baseline, 2 hours, 24 hours, 7 days and 90 days after initial dose, including high on-treatment platelet reactivity (HOPR), which was defined as P2Y12 reaction unit >208, and percentage inhibition of platelet aggregation (IPA). A total of 365 patients were included. There were 199 (54.5%) individuals classified as carriers of CYP2C19 loss-of-function alleles. For carriers and non-carriers, the proportions of HOPR were significantly lower in those with ticagrelor/aspirin compared with those with clopidogrel/aspirin at 2 hours, 24 hours, 7 days, respectively (all p<0.05). IPA was higher at all time points except at baseline in patients with ticagrelor/aspirin compared with those with clopidogrel/aspirin in both carriers and non-carriers of CYP2C19 lose-of-function alleles (all p<0.05). Our findings showed that ticagrelor/aspirin therapy possessed greater platelet inhibition and more rapid onset in platelet inhibition compared with clopidogrel/aspirin therapy both in carriers and non-carriers of CYP2C19 lose-of-function alleles with acute minor stroke or TIA.

Deep sequencing reveals the skewed B-cell receptor repertoire in plaques and the association between pathogens and atherosclerosis

The immune/inflammatory responses regulated by B cells are the critical determinants of atherosclerosis. B-cell receptor (BCR) plays pivotal roles in regulating B cell function. However, the composition and molecular characteristics of the BCR repertoire in atherosclerotic patients have not been fully elucidated. Herein we analyzed BCR repertoire in circulation and plaques of atherosclerotic patients by sequencing the BCR heavy chain complement determining region 3 (BCRH CDR3). Our data showed that in plaques, BCR repertoire was dramatically skewed and their combinations and diversity were significantly decreased, while the frequency of public and dominant B-cell clones was markedly increased. Additionally, BCRH CDR3 in plaques had higher positive selection pressure than that in the peripheral blood of normal subjects and atherosclerotic patients. Moreover, the BCRH CDR3 of some B cell clones specifically expanded in plaques were similar to that of antibodies which recognized certain pathogens including Influenza A virus, implying the possibility of the association between pathogens and atherosclerosis. The present study contributed to understand the roles of B cells in atherosclerosis. The design of specific antibodies based on the B cell clones specifically expanded in plaques might yield useful tools to reveal the pathogenesis of atherosclerosis, assess or alleviate the progression of atherosclerosis.

Pharmacodynamic Comparison of Ticagrelor Monotherapy Versus Ticagrelor and Aspirin in Patients After Percutaneous Coronary Intervention: The TEMPLATE (Ticagrelor Monotherapy and Platelet Reactivity) Randomized Controlled Trial

Background

To assess differences in platelet inhibition during ticagrelor monotherapy (TIC) or dual therapy with ticagrelor and aspirin (TIC+ASP) in patients after percutaneous coronary intervention using a comprehensive panel of functional tests.

Methods and Results

In a single‐center parallel group, open label, randomized controlled trial, 110 participants were randomized to receive either TIC (n=55) or TIC+ASP (n=55) for 4 weeks. The primary outcome was the platelet aggregation response with 10 μmol/L thrombin receptor activation peptide‐6 (TRAP‐6). The secondary outcomes were platelet aggregation responses and binding of surface activation markers with a panel of other activators. The mean percentage aggregation for 10 μmol/L TRAP‐6 was similar for the TIC and TIC+ASP groups (mean difference+4.29; 95% CI, −0.87 to +9.46). Aggregation was higher in the TIC group compared with the TIC+ASP group with 1 μg/mL (+6.47; +2.04 to +10.90) and 0.5 μg/mL (+14.00; +7.63 to +20.39) collagen related peptide. Aggregation responses with 5 μmol/L TRAP‐6, 5 μmol/L or 2.5 μmol/L thromboxane A₂ receptor agonist and surface activation marker binding with 5 μmol/L TRAP‐6 or 0.5 μg/mL collagen related peptide were the same between the treatment groups.

Conclusions

Patients with PCI show similar levels of inhibition of most platelet activation pathways with TIC compared with dual therapy with TIC + ASP. However, the greater aggregation response with collagen related peptide during TIC indicates incomplete inhibition of glycoprotein VI (collagen) receptor‐mediated platelet activation. This difference in pharmacodynamic response to anti‐platelet medication may contribute to the lower bleeding rates observed with TIC compared with dual antiplatelet therapy in recent clinical trials.

Registration Information

URL: https://www.isrctn.com; Unique Identifier ISRCTN84335288.

Comparison of platelet reactivity between prasugrel and ticagrelor in patients with acute coronary syndrome: a meta-analysis

Background

This meta-analysis aimed to compare the effects of prasugrel and ticagrelor on high (HTPR) and low on-treatment platelet reactivity (LTPR) in patients with acute coronary syndrome (ACS).

Methods

Eligible studies were retrieved from PubMed, Embase, and the Cochrane Library. HTPR and LTPR were evaluated on the basis of the vasodilator-stimulated phosphoprotein platelet reactivity index (VASP-PRI) and P2Y12 reaction units (PRUs). HTPR and LTPR were analyzed using risk ratios (RRs) and their 95% confidence intervals (CIs). Weighted mean difference (WMD) and 95% CI were used to calculate the pooled effect size of platelet reactivity (PR).

Results

Fourteen eligible studies were obtained, which included 2629 patients treated with ticagrelor (n = 1340) and prasugrel (n = 1289). The pooled results showed that the prasugrel-treated patients had higher platelet reactivity than the ticagrelor-treated patients (PRU: WMD = − 32.26; 95% CI: − 56.48 to − 8.76; P < 0.01; VASP-PRI: WMD = − 9.61; 95% CI: − 14.63 to − 4.60; P = 0.002). No significant difference in HTPR based on PRU was identified between the ticagrelor and prasugrel groups (P = 0.71), whereas a lower HTPR based on VASP-PRI was found in the ticagrelor-treated patients than in the prasugrel-treated patients (RR = 0.30; 95% CI: 0.12–0.75; P = 0.010). In addition, the results showed a lower LTPR was observed in the prasugrel group than in the ticagrelor group (RR = 1.40; 95% CI: 1.08–1.81; P = 0.01).

Conclusions

Prasugrel might enable higher platelet reactivity than ticagrelor. Ticagrelor could lead to a decrease in HTPR and increase in LTPR. However, this result was only obtained in pooled observational studies. Several uncertainties such as the nondeterminancy of the effectiveness of ticagrelor estimated using VASP-PRI or the definition of HTPR (a high or modifiable risk factor) might have affected our results.

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.