Analysis of the effect of CYP2C19 gene properties on the anti-platelet aggregation of clopidogrel after carotid artery stenting under network pharmacology.

Antiplatelet therapy is an important factor influencing the postterm patency rate of carotid artery stenting (CAS). Clopidogrel is a platelet aggregation inhibitor mediated by the adenosine diphosphate receptor and is affected by CYP2C19 gene polymorphisms in vivo. When the CYP2C19 gene has a nonfunctional mutation, the activity of the encoded enzyme will be weakened or lost, which directly affects the metabolism of clopidogrel and ultimately weakens its antiplatelet aggregation ability. Therefore, based on network pharmacology, analyzing the influence of CYP2C19 gene polymorphisms on the antiplatelet therapeutic effect of clopidogrel after CAS is highly important for the formulation of individualized clinical drug regimens. The effect of the CYP2C19 gene polymorphism on the antiplatelet aggregation of clopidogrel after CAS was analyzed based on network pharmacology. A total of 100 patients with ischemic cerebrovascular disease who were confirmed by the neurology department and required CAS treatment were studied. CYP2C19 genotyping was performed on all patients via a gene chip. All patients were classified into the wild-type (WT) group (*1/*1), heterozygous mutation (HTM) group (CYP2C19*1/*2, CYP2C19*1/*3), and homozygous mutation (HMM) group (CYP2C19*2/*2, CYP2C19*2/*3, and CYP2C19*3/*3). High-performance liquid chromatography (HPLC) with tandem mass spectrometry (MS/MS) was used to detect the blood concentration of clopidogrel and the plasma clopidogrel clearance (CL) rate in different groups of patients before and after clopidogrel treatment. The platelet aggregation rate of patients with different genotypes was measured by turbidimetry. The incidences of clopidogrel resistance (CR) and stent thrombosis in different groups after three months of treatment were analyzed. The results showed that among the different CYP2C19 genotypes, patients from the HTM group accounted for the most patients, while patients from the HTM group accounted for the least patients. Similarly, the clopidogrel CL of patients in the HMM group was lower than that of patients in the WT group and HTM group (P < 0.01). The platelet inhibition rate of patients in the HMM group was evidently inferior to that of patients in the WT group and HTM group (P < 0.01). The incidence of CR and stent thrombosis in the WT group was notably lower than that in the HTM and HMM groups (P < 0.01). These results indicate that the CYP2C19 gene can affect CR occurrence and stent thrombosis after CAS by influencing clopidogrel metabolism and platelet count.

Development and assessment of immediate-release tablets containing clopidogrel bisulphate & aspirin-strategy for optimizing the combination formulation.

The main goal of the study was to improve the compliance and convenience of patients by designing and development of an immediate release (IR) fixed-dose combination (Clopidogrel bisulphate and Aspirin) tablets. The proposed combination product utilizes Clopidogrel to protect the moisture-sensitive aspirin component, enhancing its stability against atmospheric conditions. Response-surface approach (Design Expert vs. 13) was used to generate this IR tablet by calculating the right composition of independent variables such as Microcrystalline cellulose 102, pregelatinized starch and Hydroxypropyl cellulose. 32 factorial design was used to estimate the effects of these independent variables on the responses of dependent variables (disintegration & friability) and constructed a total of nine (9) formulations. Pre and Post formulation, quality control parameters were investigated as per pharmacopeia. A systematic approach was used for the optimization process and a prototype checkpoint batch (CPB) based on the better contrast of independent variables was prepared. In vitro analysis of formulations was carried out to estimate the responses. Friability was found in the range of 0.088-1.076%w/w, except F1 = 1.076 all are within limits (NMT 1.0%). Disintegration time was recorded 7.3 ± 1.20 as lower and 24.5 ± 1.63 min was the highest. The release of drugs from their dosage form was fast and rapid, for clopidogrel after 15min was 70.42-96.82% with SD ± 8.71 and aspirin was 69.88-91.49% in 15 min with SD ± 6.41, all the tablets were released more than 80% in 20 min. The stability outcomes of CPB tablets after 15 days of stress study (60 ± 2°C and 75 ± 5%) indicated good compatibility and stability of APIs with excipients. It was concluded that the direct compression method can be preferred to prepare a combination product with cost-effectiveness. It was also concluded that the proposed methodology could increase Aspirin's stability and allow for an aqueous coating system to finish the product with a film coating. By using Design Expert software, the best composition of the formulation can be selected and optimized in a short period of time with minimum trial and errors. The results also demonstrated that the use of a fixed-dose combination tablet instead of the individual is expected to be more convenient to patients and thus improves patient compliance and decreases the occurrence of adverse effects and side effects.

Is CYP2C Haplotype Relevant for Efficacy and Bleeding Risk in Clopidogrel-Treated Patients?

A recently discovered haplotype-CYP2C:TG-determines the ultrarapid metabolism of several CYP2C19 substrates. The platelet inhibitor clopidogrel requires CYP2C19-mediated activation: the risk of ischemic events is increased in patients with a poor (PM) or intermediate (IM) CYP2C19 metabolizer phenotype (vs. normal, NM; rapid, RM; or ultrarapid, UM). We investigated whether the CYP2C:TG haplotype affected efficacy/bleeding risk in clopidogrel-treated patients. Adults (n = 283) treated with clopidogrel over 3-6 months were classified by CYP2C19 phenotype based on the CYP2C19*2*17 genotype, and based on the CYP2C19/CYP2C cluster genotype, and regarding carriage of the CYP2:TG haplotype, and were balanced on a number of covariates across the levels of phenotypes/haplotype carriage. Overall, 45 (15.9%) patients experienced ischemic events, and 49 (17.3%) experienced bleedings. By either classification, the incidence of ischemic events was similarly numerically higher in PM/IM patients (21.6%, 21.8%, respectively) than in mutually similar NM, RM, and UM patients (13.2-14.8%), whereas the incidence of bleeding events was numerically lower (13.1% vs. 16.6-20.5%). The incidence of ischemic events was similar in CYP2C:TG carries and non-carries (14.1% vs. 16.1%), whereas the incidence of bleedings appeared mildly lower in the former (14.9% vs. 20.1%). We observed no signal to suggest a major effect of the CYP2C19/CYP2C cluster genotype or CYP2C:TG haplotype on the clinical efficacy/safety of clopidogrel.

Ticagrelor downregulates the expression of proatherogenic and proinflammatory miR125-b compared to clopidogrel: A randomized, controlled trial.

BACKGROUND: Platelet P2Y12 antagonist ticagrelor reduces cardiovascular mortality after acute myocardial infarction (AMI) compared to clopidogrel, but the underlying mechanism is unknown. Because activated platelets release proatherogenic and proinflammatory microRNAs, including miR-125a, miR-125b and miR-223, we hypothesized that the expression of these miRNAs is lower on ticagrelor, compared to clopidogrel. OBJECTIVES: We compared miR-125a, miR-125b and miR-223 expression in plasma of patients after AMI treated with ticagrelor or clopidogrel. METHODS: After percutaneous coronary intervention on acetylsalicylic acid and clopidogrel, 60 patients with first AMI were randomized to switch to ticagrelor or to continue with clopidogrel. Plasma expression of miR-223, miR-125a-5p, miR-125b was measured using quantitative polymerase chain reaction at baseline and after 72 h and 6 months of treatment with ticagrelor or clopidogrel in patients and one in 30 healthy volunteers. Multiple electrode aggregometry using ADP test was used to determine platelet reactivity in response to P2Y12 inhibitors. RESULTS: Expression of miR-125b was higher in patients with AMI 72 h and 6 months, compared to healthy volunteers (p = 0.001), whereas expression of miR-125a-5p and miR-223 were comparable. In patients randomized to ticagrelor, expression of miR-125b decreased at 72 h (p = 0.007) and increased back to baseline at 6 months (p = 0.005). Expression of miR-125a-5p and miR-223 was not affected by the switch from clopidogrel to ticagrelor. CONCLUSIONS: Ticagrelor treatment leads to lower plasma expression of miR-125b after AMI, compared to clopidogrel. Higher expression of miR-125b might explain recurrent thrombotic events and worse clinical outcomes in patients treated with clopidogrel, compared to ticagrelor.

Clopidogrel induced reduction in neutrophil count: An overlooked beneficial effect?

Complement-stimulated neutrophils are able to adhere to the endothelium and damage endothelial cells both in vitro and in vivo. These blood cells participate in the early stages, growth and complications of atherosclerotic plaques. Recent findings, based on mendelian randomization analysis, support the concept that high neutrophil counts are a causal risk factor for ischemic heart disease and myocardial infarction . Clopidogrel decreases leukocyte count and inflammatory markers in patients with acute coronary syndromes; this off-target effect, which is independent of the antiplatelet action, may help explaining secondary prevention data showing a superiority of clopidogrel over aspirin in reducing new cardiovascular events.

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.

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).