Population pharmacokinetic-pharmacodynamic modeling of clopidogrel for dose regimen optimization based on CYP2C19 phenotypes: A proof of concept study.

Clopidogrel is an antiplatelet drug used to reduce the risk of acute coronary syndrome and stroke. It is converted by CYP2C19 to its active metabolite; therefore, poor metabolizers (PMs) of CYP2C19 exhibit diminished antiplatelet effects. Herein, we conducted a proof-of-concept study for using population pharmacokinetic-pharmacodynamic (PK-PD) modeling to recommend a personalized clopidogrel dosing regimen for individuals with varying CYP2C19 phenotypes and baseline P2Y12 reaction unit (PRU) levels. Data from a prospective phase I clinical trial involving 36 healthy male participants were used to develop the population PK-PD model predicting the concentrations of clopidogrel, clopidogrel H4, and clopidogrel carboxylic acid, and linking clopidogrel H4 concentrations to changes in PRU levels. A two-compartment model effectively described the PKs of both clopidogrel and clopidogrel carboxylic acid, and a one-compartment model of those of clopidogrel H4. The CYP2C19 phenotype was identified as a significant covariate influencing the metabolic conversion of the parent drug to its metabolites. A PD submodel of clopidogrel H4 that stimulated the fractional turnover rate of PRU levels showed the best performance. Monte Carlo simulations suggested that PMs require three to four times higher doses than extensive metabolizers to reach the target PRU level. Individuals within the top 20th percentile of baseline PRU levels were shown to require 2.5-3 times higher doses than those in the bottom 20th percentile. We successfully developed a population PK-PD model for clopidogrel considering the impact of CYP2C19 phenotypes and baseline PRU levels. Further studies are necessary to confirm actual dosing recommendations for clopidogrel.

Impact of selected genetic factors on clopidogrel inactive metabolite level and antiplatelet response in patients after percutaneous coronary intervention.

BACKGROUND AND OBJECTIVE: Clopidogrel is frequently used as part of optimal dual antiplatelet therapy in high-bleeding risk patients with the acute coronary syndrome. The concentration of the inactive carboxylic acid metabolite of clopidogrel might be useful to evaluate the response to clopidogrel therapy. Therefore, we sought to correlate the inhibition of platelet aggregation with the plasma level of the inactive metabolite of clopidogrel in patients after percutaneous coronary interventions (PCI) and their associations with the most frequently studied genetic polymorphisms. For this purpose, the fast and simple HPLC method for determining the concentration of the inactive metabolite was developed. METHODS: The effect of CYP2C19, CYP3A4/5, ABCB1 and PON1 genes on the plasma inactive metabolite concentration of clopidogrel and the platelet aggregation was investigated in 155 patients before and after PCI. RESULTS: The concentration of the inactive metabolite of clopidogrel was not significantly different in the intermediate metabolizers (IM) of CYP2C19 compared with extensive metabolizers (EM) both before and after PCI, while inhibition of platelet aggregation was found to be significantly better in EM than in IM. The presence of the A allele at position 2677 in the ABCB1 gene was associated with a significantly lower concentration of inactive metabolite of clopidogrel before PCI. CONCLUSION: The CYP2C19*2 allele was associated with decreased platelet reactivity during clopidogrel therapy before and after PCI. Simultaneous determination of platelet aggregation and concentration of the inactive clopidogrel metabolite may be useful in clinical practice to find the cause of adverse effects or insufficient treatment effect in patients chronically treated with clopidogrel.

Implementation of a Reference-Scaled Average Bioequivalence Approach for Highly Variable Acetylsalicylic Acid in Fixed-Dose Combination with Clopidogrel Versus Enteric Aspirin in Chinese Subjects Under Fasting Conditions: A Phase 1, Open-Label, Randomized, Crossover Study.

INTRODUCTION: Dual antiplatelet therapy, aspirin and a P2Y12 inhibitor, is recommended to prevent thrombotic complications of acute coronary syndrome. Clopidogrel plus acetylsalicylic acid combination is the most commonly used dual antiplatelet therapy recommended by international guidelines and in Chinese clinical practice. Poor adherence to dual antiplatelet therapy or premature interruption of dual antiplatelet therapy is an important contributor to cardiovascular mortality and lethal cardiovascular events. Clopidogrel + acetylsalicylic acid fixed-dose combination enhances adherence to dual antiplatelet therapy. Herein, we aimed to evaluate bioequivalence of acetylsalicylic acid and clopidogrel in fixed-dose combination compared with simultaneous administration of their individual formulations in healthy Chinese subjects under fasting conditions. METHODS: This was a randomized, single-center, open-label, three-sequence, three-period, two-treatment, crossover study with a washout period of 10 days conducted in healthy Chinese volunteers. Subjects were randomized to receive Co-Plavix® (test formulation- fixed-dose combination of 100 mg acetylsalicylic acid and 75 mg clopidogrel) once and reference formulations (coadministration of individual formulations of 100 mg acetylsalicylic acid and 75 mg clopidogrel) twice during the study period. Pharmacokinetic parameters were analyzed for acetylsalicylic acid, its metabolite salicylic acid, clopidogrel, and its metabolite SR26334. As acetylsalicylic acid shows high intrasubject variability, the reference-scaled average bioequivalence (RSABE) approach was implemented for acetylsalicylic acid analysis, while bioequivalence of clopidogrel was assessed using the average bioequivalence method. Point ratios and confidence intervals (CIs) for AUC, AUClast, and Cmax for acetylsalicylic acid and clopidogrel were calculated. RESULTS: In total, 171 healthy subjects were enrolled in this study. Subjects were randomized and 170 subjects were treated with test or reference formulation; 164 subjects completed the study. Regarding acetylsalicylic acid exposure, as reference within-subject standard deviation (SDW) was at least 0.294 for acetylsalicylic acid Cmax, AUClast, and AUC, the RSABE analysis method was used to assess bioequivalence for all three parameters. The point estimates were within the 0.80-1.25 range (1.19, 1.09, and 1.04, respectively), and upper one-sided 95% CIs of scaled average bioequivalence metric were at most 0 (- 0.30, - 0.14, and - 0.10, respectively). Thus, bioequivalence was demonstrated with acetylsalicylic acid. Bioequivalence was also achieved with clopidogrel as the 90% CIs for geometric mean ratios of clopidogrel Cmax, AUClast, and AUC were within the bioequivalence range (0.80-1.25). CONCLUSION: Application of the reference-scaled average bioequivalence approach to evaluate bioequivalence of acetylsalicylic acid in Chinese male and female healthy volunteers under fasting conditions demonstrated bioequivalence of test and reference formulations. TRIAL REGISTRATION: CTR20181695.

Inhibition of carboxylesterase-1 alters clopidogrel metabolism and disposition.

Clopidogrel is widely prescribed in patients with cardiovascular disease. Most research has focused on the role of hepatic CYP450 metabolism as the primary source of response variability despite 85-90% of clopidogrel being hydrolyzed by human carboxylesterase-1 (CES1).The purpose of this study is to determine the effects of the known CES1 inhibitor alcohol on clopidogrel metabolism: (1) in vitro in human recombinant CES1 and human liver S9 (HLS9) fractions and (2) in a plasma carboxylesterase deficient mouse (Es1e) strain administered 25 mg/kg oral clopidogrel alone and with 3 g/kg alcohol.Alcohol significantly inhibited the hydrolysis of clopidogrel (IC50 161 mM) and 2-oxo-clopidogrel (IC50 6 mM). In HLS9, alcohol treatment formed ethylated metabolites via transesterification and an increased formation of the H4 active metabolite. These results were replicated in Es1e mice as alcohol increased clopidogrel (91%) and H4 (22%) AUC and reduced formation of the clopidogrel (48%) and 2-oxo-clopidogrel (42%) carboxylate metabolites.Clopidogrel metabolism is highly sensitive to alterations in CES1 activity. The Es1e mouse may represent a suitable model of human CES1 drug metabolism that can be used to rapidly assess how alterations in CES1 function impact the disposition of substrate drugs.

Very complex internal standard response variation in LC-MS/MS bioanalysis: root cause analysis and impact assessment.

Internal standards (ISs) are essential for the development and use of reliable quantitative bioanalytical LC-MS/MS methods, because they correct for fluctuations in the analytical response that are caused by variations in experimental conditions. Sample-to-sample differences in the IS response are thus to be expected, but a large variability often is an indication of nonoptimal sample handling or analysis settings. This paper discusses a number of cases of very complex variation of IS responses that could be attributed to analytical problems such as injection errors and sample inhomogeneity, and matrix-related issues such as degradation and increased ionization efficiency. A decision tree is proposed to help find the underlying root cause for extreme IS variability.

Effectiveness of Platelet Function Analyzer-100 for Laboratory Detection of Anti-Platelet Drug-Induced Platelet Dysfunction.

BACKGROUND: High on-treatment platelet reactivity (HTPR) is the phenomenon wherein patients exhibit normal platelet activity in laboratory testing despite adequate adherence to anti-platelet treatment. We investigated the detection rates of Platelet Function Analyzer (PFA)-100 (Dade Behring AG, Düdingen, Switzerland) for drug-induced platelet dysfunction and analyzed potential contributors to HTPR with practical PFA-100 data over six years. METHODS: We used data from 6,957 patients who underwent PFA-100 testing after receiving aspirin, clopidogrel, or non-steroidal anti-inflammatory drugs (NSAIDs). Of these, 6,163 patients were tested with only the collagen/epinephrine cartridge (Col/EPI) of PFA-100; 794 were tested with both Col/EPI and the collagen/ADP cartridge (Col/ADP). We calculated PFA-100 closure time (CT) for each drug and compared the clinical and laboratory characteristics of the patients with prolonged CTs and normal CTs (i.e., HTPR). RESULTS: In Col/EPI, 73.2% (365/499), 72.6% (390/537), and 55.3% (3,442/6,228) patients showed prolonged CTs for aspirin, clopidogrel, and NSAIDs, respectively. In Col/ADP, prolonged CTs were observed in 37.4% (34/91), 43.2% (35/81), and 29.6% (200/676) of patients receiving aspirin, clopidogrel, and NSAIDs, respectively. Of the patients tested with both cartridges, 88.9% (48/54), 95.3% (41/43), and 89.0% (577/648) of the patients receiving aspirin, clopidogrel, and NSAIDs had prolonged CTs, and 10.0% (79/794) showed normal CTs regardless of drugs. For clopidogrel users (both cartridges), there were more patients with malignancies in the normal CT than prolonged CT group. CONCLUSIONS: PFA-100 is not sufficiently effective for laboratory screening of drug-induced platelet dysfunction. Malignancy may contribute to clopidogrel-related HTPR in PFA-100.

Beneficial effects of combined administration of Clopidogrel and Aspirin on the levels of proinflammatory cytokines, cardiac function, and prognosis in ST-segment elevation myocardial infarction: A comparative study.

OBJECTIVE: Both Aspirin and Clopidogrel are considered as effective drugs in decreasing ischemic events, which potentially contribute to a promising application regarding the cardiovascular events. In the present study, we evaluated the efficacy of the combination of both Clopidogrel and Aspirin to determine the influence among inflammatory factors, cardiac function, and treatment outcome of patients suffering from ST-segment elevation myocardial infarction (STEMI) in the Hebei province of China. METHODS: To compare the efficacy of this combination therapy with a single Aspirin treatment, we experimented in 68 patients with the administration of both Clopidogrel and Aspirin as well as another 68 patients administered only with Aspirin. An enzyme-linked immunosorbent assay was used to measure the expression of inflammatory factors, thereby evaluating the effect on inflammation. In addition, a series of indexes related to cardiac function and renal function were monitored by use of a color Doppler ultrasound and an automatic biochemical analyzer, respectively. Myocardial injury-related indicators were detected. A multivariate logistic regression analysis was performed so we could identify potential risk factors. In addition, both postoperative hemorrhages and cardiac events were observed to evaluate the treatment outcome of patients with STEMI. RESULTS: Initially, the treatment outcome revealed a better efficacy in patients treated with the combination of both Clopidogrel and Aspirin, with the patients also showing more obviously alleviated myocardial injury, better cardiac and renal functions with lower serum levels of inflammatory factors. The lower incidence of postinfarction angina, recurrent myocardial infarction, stroke, and death also provide evidence that patients showed a better outcome after treatment with both Clopidogrel and Aspirin. CONCLUSION: Taken together, the combination therapy of Clopidogrel and Aspirin provided a better improvement on both the cardiac function and outcome of STEMI patients in the Hebei province of China, with reduced inflammation as well.

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

BACKGROUND: Limitations have been observed with the use of clopidogrel following percutaneous coronary intervention (PCI) indicating the urgent need of a more potent anti-platelet agent. We aimed to compare the efficacy and safety of ticagrelor versus clopidogrel following PCI. METHODS: Online databases were searched for relevant studies (published between the years 2007 and 2017) comparing ticagrelor versus clopidogrel following coronary stenting. Primary outcomes assessed efficacy whereas secondary outcomes assessed safety. Odds ratios (OR) with 95% confidence intervals (CIs) based on a random effect model were calculated and the analysis was carried out by the RevMan 5.3 software. RESULTS: A total number of 25,632 patients with acute coronary syndrome (ACS) [12,992 patients with ST segment elevation myocardial infarction (STEMI) and 14,215 patients with non-ST segment elevation myocardial infarction (NSTEMI)] were included in this analysis, of whom 23,714 patients were revascularized by PCI. Results of this analysis did not show any significant difference in all-cause mortality, major adverse cardiac events (MACEs), myocardial infarction, stroke and stent thrombosis observed between ticagrelor and clopidogrel with (OR: 0.83, 95% CI: 0.67-1.03; P = .09), (OR: 0.64, 95% CI: 0.41-1.01; P = .06), (OR: 0.77, 95% CI: 0.57-1.03; P = .08), (OR: 0.85, 95% CI: 0.57-1.26; P = .42) and (OR: 0.70, 95% CI: 0.47-1.05; P =.09).However, ticagrelor was associated with a significantly higher minor and major bleeding with (OR: 1.57, 95% CI: 1.30-1.89; P = .00001) and (OR: 1.52, 95% CI: 1.01-2.29; P = 0.04) respectively. Dyspnea was also significantly higher in the ticagrelor group (OR: 2.64, 95% CI: 1.87-3.72; P = .00001). CONCLUSION: Ticagrelor and clopidogrel were comparable in terms of efficacy in these patients with ACS. However, the safety outcomes of ticagrelor should further be investigated.

[The association of lipid profile and bleeding in patients with minor stroke or transient ischemic attack on antiplatelet therapy: subgroup analysis of CHANCE].

Objective: Abnormalities of lipid profile were considered as risk factors of hemorrhage after ischemic stroke. We aimed to determine the relationship between lipid levels and bleeding in minor stroke or transient ischemic attack (TIA) patients receiving antiplatelet therapy. Methods: Serum total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglyceride were tested in a subgroup of 3 044 consecutive patients from Clopidogrel in High-risk patients with Acute Non-disabling Cerebrovascular Events (CHANCE) trial. Patients were randomized to clopidogrel plus aspirin group or single aspirin group. The primary endpoint was any bleeding within 90 days. The secondary endpoint was severe bleeding according to the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO) definition. Cox proportional hazards models were used to assess the associations of lipid levels and outcomes. Results: A total of 59 (1.9%) bleeding events occurred at 90 days. High-density lipoprotein cholesterol (adjusted HR=2.16; 95%CI 1.17-4.00, P=0.014) and age (adjusted HR=1.04; 95%CI 1.01-1.06, P=0.006) were significantly associated with any bleeding. High-density lipoprotein cholesterol was also associated with severe bleeding (adjusted HR=3.05; 95%CI 1.39-6.68, per 1 mmol/L increase). No correlations between outcomes and levels of total cholesterol, low-density lipoprotein cholesterol and triglyceride were found. There was no interaction of any lipid component level with randomized antiplatelet therapy. Conclusions: Elevated high-density lipoprotein cholesterol is independently associated with any bleeding and severe bleeding in the patients with acute minor stroke or high-risk TIA on antiplatelet therapy.

The association of clopidogrel and 2-oxo-clopidogrel plasma levels and the 40 months clinical outcome after primary PCI.

Background A significant number of ischemic events occur even when adhering to dual antiplatelet therapy including aspirin and clopidogrel. Objectives The aim of our study was to determine predictors of long-term patient clinical outcome, among variables such as prodrug clopidogrel and intermediary metabolite 2-oxoclopidogrel concentrations, as well as patients' clinical characteristics. Setting Department for the Treatment of Acute Coronary Syndrome in tertiary teaching hospital, Serbia. Methods This study enrolled 88 consecutive patients with first STEMI, treated with primary PCI, within 6 h of the chest pain onset and followed them 40 months. On the third day of hospitalization, blood samples were collected from each patient to measure clopidogrel and its metabolite 2-oxo-clopidogrel concentration by UHPLC-DAD-MS method. Main outcome measure Mortality from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke or hospitalization for urgent myocardial revascularization or heart failure. Results The composite clinical outcome of cardiovascular mortality, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for urgent myocardial revascularization or heart failure, was registered in 31 patients (35.2%) during the 40-month follow-up. Lower clopidogrel (p < 0.05) and dose-adjusted clopidogrel concentrations (p < 0.05) were associated with the higher incidence of composite outcome events. Their low plasma concentrations may be predicted by fentanyl administration (p < 0.001) and creatinine clearance (p < 0.01). The decrease in dose-adjusted clopidogrel unit for each ng/ml/mg increases the risk 21.7 times (p < 0.05). Conclusion Clopidogrel dose-adjusted plasma concentration in STEMI patients, as well as multivessel coronary artery disease, showed significance in predicting an unfavorable composite clinical outcome after 40-month follow-up.

Ticagrelor plus aspirin for 1 month, followed by ticagrelor monotherapy for 23 months vs aspirin plus clopidogrel or ticagrelor for 12 months, followed by aspirin monotherapy for 12 months after implantation of a drug-eluting stent: a multicentre, open-label, randomised superiority trial.

BACKGROUND: We hypothesised that ticagrelor, in combination with aspirin for 1 month, followed by ticagrelor alone, improves outcomes after percutaneous coronary intervention compared with standard antiplatelet regimens. METHODS: GLOBAL LEADERS was a randomised, open-label superiority trial at 130 sites in 18 countries. Patients undergoing percutaneous coronary intervention with a biolimus A9-eluting stent for stable coronary artery disease or acute coronary syndromes were randomly assigned (1:1) to 75-100 mg aspirin daily plus 90 mg ticagrelor twice daily for 1 month, followed by 23 months of ticagrelor monotherapy, or standard dual antiplatelet therapy with 75-100 mg aspirin daily plus either 75 mg clopidogrel daily (for patients with stable coronary artery disease) or 90 mg ticagrelor twice daily (for patients with acute coronary syndromes) for 12 months, followed by aspirin monotherapy for 12 months. Randomisation was concealed, stratified by centre and clinical presentation (stable coronary artery disease vs acute coronary syndrome), and blocked, with randomly varied block sizes of two and four. The primary endpoint at 2 years was a composite of all-cause mortality or non-fatal centrally adjudicated new Q-wave myocardial infarction as assessed by a core lab in a blinded manner. The key secondary safety endpoint was site-reported bleeding assessed according to the Bleeding Academic Research Consortium criteria (grade 3 or 5). Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01813435, and is closed to new participants, with follow-up completed. FINDINGS: Between July 1, 2013, and Nov 9, 2015, 15 968 participants were randomly assigned, 7980 to the experimental group and 7988 to the control group. At 2 years, 304 (3·81%) participants in the experimental group had died or had a non-fatal centrally adjudicated new Q-wave myocardial infarction, compared with 349 (4·37%) participants in the control group (rate ratio 0·87 [95% CI 0·75-1·01]; p=0·073]). There was no evidence for a difference in treatment effects for the primary endpoint across prespecified subgroups of acute coronary syndromes and stable coronary artery disease (p=0·93). Grade 3 or 5 bleeding occurred in 163 participants in the experimental group and 169 in the control group (2·04% vs 2·12%; rate ratio 0·97 [95% CI 0·78-1·20]; p=0·77). INTERPRETATION: Ticagrelor in combination with aspirin for 1 month followed by ticagrelor alone for 23 months was not superior to 12 months of standard dual antiplatelet therapy followed by 12 months of aspirin alone in the prevention of all-cause mortality or new Q-wave myocardial infarction 2 years after percutaneous coronary intervention. FUNDING: AstraZeneca, Biosensors, and The Medicines Company.

Comparison of Effects between Clopidogrel and Cilostazol on Cerebral Perfusion in Nonsurgical Adult Patients with Symptomatically Ischemic Moyamoya Disease: Subanalysis of a Prospective Cohort.

BACKGROUND AND PURPOSE: Adult patients with symptomatically ischemic moyamoya disease (MMD) initially undergo medical treatment alone including antiplatelet drugs when symptomatic cerebral hemispheres do not exhibit hemodynamic compromise. The purpose of the present study subanalyzing the same patient cohort used in a previous study was to determine which antiplatelet drug, clopidogrel or cilostazol, provides better improvement of cerebral perfusion in such patients. METHODS: All patients without cerebral misery perfusion on 15O gas positron emission tomography (PET) did not undergo revascularization surgery and were treated with medication alone, including antiplatelet therapy. Patients ≥50years and <50years initially received clopidogrel and cilostazol, respectively. When a patient suffered side effects of an antiplatelet drug, they were switched to the other antiplatelet drug. Cerebral blood flow (CBF) in the symptomatic hemisphere was measured at inclusion and at 2years after inclusion using 15O gas PET. RESULTS: Of 68 patients, 31 and 38 were treated with clopidogrel and cilostazol, respectively, for 2years after inclusion. For patients treated with clopidogrel, CBF did not differ between first and second PET. For patients treated with cilostazol, CBF was significantly greater in the second PET than in the first PET. On multivariate analysis, cilostazol administration was an independent predictor of CBF improvement in the symptomatic hemisphere (95% confidence interval, 1.34-139.20; P =.0271). CONCLUSIONS: Cilostazol improves cerebral perfusion better than clopidogrel in adult patients with symptomatically ischemic MMD not accompanied by misery perfusion.

Aspirin plus clopidogrel may reduce the risk of early neurologic deterioration in ischemic stroke patients carrying CYP2C19*2 reduced-function alleles.

OBJECTIVES: The mechanisms of early neurologic deterioration (END) and prevention strategies for END are not completely understood. The aim of this study was to investigate the association between CYP2C19*2 variants and END, and the effectiveness of antiplatelet therapy for prevention of END according to CYP2C19*2 genotypes in patients with ischemic stroke (IS). MATERIALS AND METHODS: This was a two-center, randomized controlled study. Between August 2009 and December 2011, 570 IS patients were randomly assigned to clopidogrel plus aspirin group (n = 284) or aspirin alone group (n = 286). Platelet aggregation and platelet-leukocyte aggregates were measured before and after 7-10 days of treatment. CYP2C19*2 (rs4244285) genotypes were examined using mass spectrometry. The primary outcome was END during the 10 days of admission. RESULTS: Among the 570 patients, 121 (21.2%) patients suffered from END. Carriers of CYP2C19*2 reduced-function alleles were associated with higher incidence of END (26.8% in carriers vs. 16.6% in noncarriers, P = 0.004). The incidence of END was lower in the clopidogrel plus aspirin group than in the aspirin alone group (17.6 vs. 24.8%, P = 0.032). Stratified analyses revealed that clopidogrel plus aspirin could be more effective in reducing END than aspirin alone for carriers of CYP2C19*2 reduced-function alleles (18.8 vs. 34.9%, P = 0.006). However, there was no significant difference in incidence of END between dual therapy group and monotherapy group for noncarriers (16.7 vs. 16.6%, P = 0.998). CONCLUSIONS: Dual therapy with clopidogrel and aspirin may be adequate for prevention of END in carriers of CYP2C19 reduced-function alleles, but not for noncarriers. Our findings may be useful to guide precise antiplatelet therapy, and decrease the risk of END.

CRISPLD1 rs12115090 polymorphisms alters antiplatelet potency of clopidogrel in coronary artery disease patients in Chinese Han.

BACKGROUND: Dual antiplatelet therapy (DAPT) with aspirin and clopidogrel is a recommended treatment for coronary artery disease (CAD) patients undergoing percutaneous coronary intervention (PCI) to reduce the rate of ischemic events and stent thrombosis. However, high on-treatment platelet reactivity (HTPR) during clopidogrel therapy for some patients may lead to outcome failure and occurrence of cardiovascular events. Amounts of studies have proved that genetic factors may contribute to HTPR. In our study, we explored the predictive value of 10 single nucleotide polymorphisms (SNPs) in 8 genes indicated by exome sequencing with clopidogrel efficacy. METHODS: Two hundred and forty-one Han Chinese CAD patients (mean age: 61 ±â€¯10 years) receiving dual antiplatelet therapy were recruited, among which 118 patients administered with 300 mg loading dose (LD) clopidogrel for 12-24 h and 123 subjects administered with 75 mg/day maintain dose (MD) clopidogrel for at least 5 days before discharge. The platelet reaction index (PRI) was determined to reflect clopidogrel response in the patients. Venous blood samples were drawn from all participants to extract genomic DNA. MassARRAY, Sanger sequencing and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) were used to determine the genotypes of 10 SNPs. RESULTS: Allelic tests showed significant differences in genotype distribution between HTPR and normal on-treatment platelet reactivity (NTPR) patients for 3 SNPs including CYP2C19 rs4244285 (CYP2C19*2) (co-dominant model: p = 0.003, dominant model: p = 0.004, recessive model: p = 0.012), CRISPLD1 rs12115090 (co-dominant model: p = 0.011, dominant model: p = 0.004), and LTA4H rs11108379 (dominant model: p = 0.041). After adjusting for covariates including clinical characteristics of patients, concomitant medications and complications, we confirmed that carriers of the CYP2C19*2 showed significantly increased risk of HTPR (*2/*2 vs *1/*1: OR = 12.266, 95% CI: 1.336-112.592, p = 0.027; *1/*2 + *2/*2 vs *1/*1: OR = 2.202, 95% CI: 1.083-4.480, p = 0.029). Contrarily, carriers of the CRISPLD1 rs12115090 C allele showed significantly reduced risk of HTPR (CC vs AA: OR = 0.242, 95% CI: 0.078-0.752, p = 0.014; CA + CC vs AA: OR = 0.457, 95% CI: 0.232-0.904, p = 0.024) in Chinese CAD patients. In addition, carriers of the CYP2C19*2 allele showed significantly increased PRI (*1/*2 vs *1/*1: p = 0.008, 2/*2 vs 1/*1: p < 0.001, *2/*2 vs 1/*2: p = 0.011), while patients carrying the rs12115090 C allele showed significantly decreased PRI than the wild-type AA homozygotes (CA vs AA: p = 0.046, CA + CC vs AA: p = 0.023). CONCLUSION: CYP2C19*2 reduced the antiplatelet potency of clopidogrel and increased the risk of HTPR, while CRISPLD1 rs12115090 A>C polymorphism increased the antiplatelet potency of clopidogrel. Genetic tests, especially for CYP2C19*2 are recommended in Han Chinese CAD patients before using of clopidogrel.

Influence of cytochrome P450 polymorphisms on the antiplatelet effects of prasugrel in patients with non-cardioembolic stroke previously treated with clopidogrel.

This randomized double-blind crossover study aimed to investigate the influence of cytochrome P450 (CYP) 2C19 polymorphisms on the antiplatelet effects of prasugrel in patients with non-cardioembolic stroke treated with clopidogrel. Patients received clopidogrel 75 mg/day for > 4 weeks. Subsequently, patients received prasugrel 3.75 mg/day (group A; n = 64) or 2.5 mg/day (group B; n = 65) for 4 weeks followed by a 4 week switched-dose regimen. To assess the influence of CYP2C19 polymorphisms, patients were classified as extensive metabolizers (EMs), intermediate metabolizers (IMs), and poor metabolizers (PMs). The primary endpoint was P2Y12 reaction units (PRU) at the end of each 4 week treatment. A significant reduction in PRU was noted after treatment with prasugrel 3.75 mg/day compared with the pre-dose value (after treatment with clopidogrel) (p < 0.0001). By CYP2C19 phenotypes, a significant reduction in PRU was noted in IMs and PMs after treatment with prasugrel 3.75 mg/day and in PMs after treatment with prasugrel 2.5 mg/day, as compared with the pre-dose value (p < 0.0001). The plasma concentration of the active metabolite of clopidogrel was relatively low in PMs compared to EMs and IMs; prasugrel was similar across all CYP2C19 phenotypes. No major or clinically significant hemorrhagic adverse events occurred. By CYP2C19 phenotype, the antiplatelet effects of prasugrel were greater with 3.75 mg/day in IMs and PMs, and with 2.5 mg/day in PMs compared with clopidogrel 75 mg/day, without safety concerns. CYP2C19 polymorphisms did not affect the plasma concentration of the active metabolite of prasugrel or its antiplatelet effects. (JapicCTI-101044).

Association between high on-treatment platelet reactivity to clopidogrel and hepatosteatosis in patients undergoing elective stent implantation.

OBJECTIVE: The present study is an investigation of the association between high on-treatment platelet reactivity to clopidogrel (HTPRC) and hepatosteatosis in patients who had elective stent implantation due to coronary artery disease. METHODS: A total of 190 consecutive patients who underwent an elective coronary stent implantation due to coronary artery disease were prospectively enrolled in the study. Eligible patients were given a 300 mg loading dose of clopidogrel before percutaneous coronary intervention. All of the patients underwent an ultrasound assessment for fatty liver. The patients were divided into 2 groups according to the detection of HTPRC: patients with HTPRC and patients without HTPRC. RESULTS: HTPRC was present in 54.2% (103 of 190 patients) of the total study population. The age and body mass index data were similar between the 2 groups. In all, 111 (58.6%) patients had hepatosteatosis. The HTPRC ratio was statistically higher in female patients (p=0.032). Hepatosteatosis was significantly greater in patients with HTPRC (p<0.001); 84 (81.6%) patients with HTPRC had hepatosteatosis (p=0.001). There was also a statistically significant association between the hepatosteatosis grade and HTPRC (p<0.001). The percentage of HTPRC was greater in patients with ≥grade 2 hepatosteatosis than grade 1 (p<0.001). Logistic regression analysis indicated that hepatosteatosis (odds ratio: 9.403, 95% confidence interval: 4.519-19.566; p<0.001), fasting blood glucose, and hypertension were independent predictors of HTPRC. CONCLUSION: To the best of our knowledge, this is the first study to demonstrate a relationship between hepatosteatosis and HTPRC.

Continuation versus discontinuation of antiplatelet therapy for bleeding and ischaemic events in adults undergoing non-cardiac surgery.

BACKGROUND: Antiplatelet agents are recommended for people with myocardial infarction and acute coronary syndromes, transient ischaemic attack or stroke, and for those in whom coronary stents have been inserted. People who take antiplatelet agents are at increased risk of adverse events when undergoing non-cardiac surgery because of these indications. However, taking antiplatelet therapy also introduces risk to the person undergoing surgery because the likelihood of bleeding is increased. Discontinuing antiplatelet therapy before surgery might reduce this risk but subsequently it might make thrombotic problems, such as myocardial infarction, more likely. OBJECTIVES: To compare the effects of continuation versus discontinuation for at least five days of antiplatelet therapy on the occurrence of bleeding and ischaemic events in adults undergoing non-cardiac surgery under general, spinal or regional anaesthesia. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 1), MEDLINE (1946 to January 2018), and Embase (1974 to January 2018). We searched clinical trials registers for ongoing studies, and conducted backward and forward citation searching of relevant articles. SELECTION CRITERIA: We included randomized controlled trials of adults who were taking single or dual antiplatelet therapy, for at least two weeks, and were scheduled for elective non-cardiac surgery. Included participants had at least one cardiac risk factor. We planned to include quasi-randomized studies.We excluded people scheduled for minor surgeries under local anaesthetic or sedation in which bleeding that required transfusion or additional surgery was unlikely. We included studies which compared perioperative continuation of antiplatelet therapy versus discontinuation of antiplatelet therapy or versus substitution of antiplatelet therapy with a placebo for at least five days before surgery. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed studies for inclusion, extracted data, assessed risk of bias and synthesized findings. Our primary outcomes were: all-cause mortality at longest follow-up (up to six months); all-cause mortality (up to 30 days). Secondary outcomes included: blood loss requiring transfusion of blood products; blood loss requiring further surgical intervention; risk of ischaemic events. We used GRADE to assess the quality of evidence for each outcome MAIN RESULTS: We included five RCTs with 666 randomized adults. We identified three ongoing studies.All study participants were scheduled for elective general surgery (including abdominal, urological, orthopaedic and gynaecological surgery) under general, spinal or regional anaesthesia. Studies compared continuation of single or dual antiplatelet therapy (aspirin or clopidogrel) with discontinuation of therapy for at least five days before surgery.Three studies reported adequate methods of randomization, and two reported methods to conceal allocation. Three studies were placebo-controlled trials and were at low risk of performance bias, and three studies reported adequate methods to blind outcome assessors to group allocation. Attrition was limited in four studies and two studies had reported prospective registration with clinical trial registers and were at low risk of selective outcome reporting bias.We reported mortality at two time points: the longest follow-up reported by study authors up to six months, and time point reported by study authors up to 30 days. Five studies reported mortality up to six months (of which four studies had a longest follow-up at 30 days, and one study at 90 days) and we found that either continuation or discontinuation of antiplatelet therapy may make little or no difference to mortality up to six months (risk ratio (RR) 1.21, 95% confidence interval (CI) 0.34 to 4.27; 659 participants; low-certainty evidence); the absolute effect is three more deaths per 1000 with continuation of antiplatelets (ranging from eight fewer to 40 more). Combining the four studies with a longest follow-up at 30 days alone showed the same effect estimate, and we found that either continuation or discontinuation of antiplatelet therapy may make little or no difference to mortality at 30 days after surgery (RR 1.21, 95% CI 0.34 to 4.27; 616 participants; low-certainty evidence); the absolute effect is three more deaths per 1000 with continuation of antiplatelets (ranging from nine fewer to 42 more).We found that either continuation or discontinuation of antiplatelet therapy probably makes little or no difference in incidences of blood loss requiring transfusion (RR 1.37, 95% CI 0.83 to 2.26; 368 participants; absolute effect of 42 more participants per 1000 requiring transfusion in the continuation group, ranging from 19 fewer to 119 more; four studies; moderate-certainty evidence); and may make little or no difference in incidences of blood loss requiring additional surgery (RR 1.54, 95% CI 0.31 to 7.58; 368 participants; absolute effect of six more participants per 1000 requiring additional surgery in the continuation group, ranging from seven fewer to 71 more; four studies; low-certainty evidence). We found that either continuation or discontinuation of antiplatelet therapy may make little or no difference to incidences of ischaemic events (to include peripheral ischaemia, cerebral infarction, and myocardial infarction) within 30 days of surgery (RR 0.67, 95% CI 0.25 to 1.77; 616 participants; absolute effect of 17 fewer participants per 1000 with an ischaemic event in the continuation group, ranging from 39 fewer to 40 more; four studies; low-certainty evidence).We used the GRADE approach to downgrade evidence for all outcomes owing to limited evidence from few studies. We noted a wide confidence in effect estimates for mortality at the end of follow-up and at 30 days, and for blood loss requiring transfusion which suggested imprecision. We noted visual differences in study results for ischaemic events which suggested inconsistency. AUTHORS' CONCLUSIONS: We found low-certainty evidence that either continuation or discontinuation of antiplatelet therapy before non-cardiac surgery may make little or no difference to mortality, bleeding requiring surgical intervention, or ischaemic events. We found moderate-certainty evidence that either continuation or discontinuation of antiplatelet therapy before non-cardiac surgery probably makes little or no difference to bleeding requiring transfusion. Evidence was limited to few studies with few participants, and with few events. The three ongoing studies may alter the conclusions of the review once published and assessed.

Comparison of the Effects of Ticagrelor and Clopidogrel on Inflammatory Factors, Vascular Endothelium Functions and Short-Term Prognosis in Patients with Acute ST-Segment Elevation Myocardial Infarction Undergoing Emergency Percutaneous Coronary Intervention: a Pilot Study.

BACKGROUND/AIMS: Acute ST-segment elevation of myocardial infarction (STEMI) is the most severe type of acute coronary syndrome (ACS). Particular attention has been focused on studying the pathogenesis of STEMI, and how to prevent thrombosis, reduce inflammatory reaction, stabilize plaques and improve vascular endothelial functions to preserve the survived myocardium. This study aimed to compare the anti-inflammatory endothelium-protective effects, clinical prognosis, and relevant bleeding risks of ticagrelor versus clopidogrel in patients with STEMI who underwent urgent percutaneous coronary intervention (PCI) and provide certain experimental evidence and a theoretical basis for the selection of safe and effective drugs and their proper dosage, thereby further guiding clinical medication. METHODS: We sequentially enrolled 193 patients (104 males and 89 females) admitted to hospital due to acute STEMI. These patients underwent urgent PCI between December 2013 and May 2015 and met the inclusion criteria. They were assigned (1: 1) into two groups according to different treatments, 97 patients in the ticagrelor group (treatment group), and 96 patients in the clopidogrel group (control group). Levels of hypersensitive C-reactive protein (hs-CRP), interleukin-6 (IL-6), and endothelial cell-specific molecule 1 (ESM-1) taken at admission and 24 h, 4 days, and 7 days after administration, as well as the correlation between the levels of IL-6, hs-CRP, and ESM-1, were determined in the two groups. At the same time, the effects of treatment with ticagrelor and clopidogrel on the efficacy endpoint events (ischemic and safety) were explored. RESULTS: No statistically significant difference was found in the levels of hs-CRP, IL-6, or ESM-1 at admission between the two groups (P> 0.05); Their levels were significantly elevated 24 h after administration, with statistical differences between two groups (P< 0.05). Furthermore, a downward trend with statistically significant differences was found on Day 4 and Day 7 (P< 0.05); ESM-1 levels increased along with increases of hs-CRP and IL-6 levels, indicating ESM-1 was positively correlated with hs-CRP (r=0.523, P< 0.001) and IL-6 (r=0.431, P< 0.001); and the occurrence rates of ischemic endpoint events at 30 days were lower in the treatment group than in the control group. The occurrence of safety endpoint events was higher than in the control group; however, no statistically significant difference was found (P> 0.05). CONCLUSIONS: Compared with clopidogrel, ticagrelor appears to rapidly reduce the prevalence of inflammatory reactions and stabilize the functions of vascular endothelium to improve the stability of atherosclerotic plaque and decrease the occurrence rate of thrombosis as well as ischemic outcome events without any obvious increase in the risk of bleeding in patients with acute STEMI receiving urgent PCI. This renders it a potential drug for clinical practice. At the same time, measurement of ESM-1, a new biological marker for vascular endothelial function disorder, could possibly become a simple, effective, and practical new method for clinical evaluation of risk stratification of patients with acute STEMI at admission.

[Anti-Thrombotic Treatment of Patients with Peripheral Artery Disease (PAD)]. / Antithrombotische Therapie bei peripherer arterieller Verschlusskrankheit.

Patients with peripheral artery disease are at high-risk for cardiovascular events. Anti-thrombotic treatment is very important for secondary prevention. In symptomatic patients single antiplatelet therapy with clopidogrel or Aspirin is recommended. After peripheral revascularisation transient dual antiplatelet therapy is widely used although there is only little evidence. Following peripheral bypass surgery most patients are treated with single antiplatelet therapy, in some cases (prostetic bypass grafts) dual antiplated therapy can be useful and selected patients with complex venous grafts might profit from anticoagulation with vitamin K antagonists.The recent publication of the COMPASS (Cardiovascular OutcoMes for People Using Anticoagulation StrategieS) study showed relevant reduction of MACE (Major Adverse Cariac Events) and MALE (Major Adverse Limb Events) for the combined therapy of rivaroxaban 2 × 2,5 mg compared to Aspirin 100 mg with increased risk for gastrointestinal bleeding. In the current VOYAGER PAD (Vascular Outcomes Study of Aspirin along with Rivaroxaban in Endovascular or Surgical Limb Revascularization for PAD) study this concept is tested after peripheral revascularisation.