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, AUC_last, and C_max 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 (SD_W) was at least 0.294 for acetylsalicylic acid C_max, AUC_last, 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 C_max, AUC_last, 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.

Electronic supplementary material

The online version of this article (10.1007/s12325-020-01369-z) contains supplementary material, which is available to authorized users.

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.

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.

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.

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.

Development, validation and application of a novel HPLC-MS/MS method for the quantification of atorvastatin, bisoprolol and clopidogrel in a large cardiovascular patient cohort

Cardiovascular disease is a leading cause of morbidity, mortality, and healthcare expenditure worldwide. Importantly, there is interindividual variation in response to cardiovascular medications, leading to variable efficacy and adverse events. Therefore a rapid, selective, sensitive and reproducible multi-analyte HPLC-MS/MS assay for the quantification in human plasma of atorvastatin, its major metabolites 2-hydroxyatorvastatin, atorvastatin lactone and 2-hydroxyatorvastatin lactone, plus bisoprolol and clopidogrel-carboxylic acid has been developed, fully validated, and applied to a large patient study. Fifty microliter plasma samples were extracted with a simple protein precipitation procedure involving acetonitrile with acetic acid (0.1%, v/v). Chromatographic separation was via a 2.7 μm Halo C18 (50 × 2.1 mm ID, 90 Å) column and gradient elution at a flow rate of 500 μL/min consisting of a mobile phase of water (A) and acetonitrile (B), each containing 0.1% formic acid (v/v), over a 6.0 min run time. The six analytes and their corresponding six deuterated internal standards underwent positive ion electrospray ionisation and were detected with multiple reaction monitoring. The developed method was fully validated with acceptable selectivity, carryover, dilution integrity, and within-run and between-run accuracy and precision. Mean extraction recovery for the analytes was 92.7-108.5%, and internal standard-normalised matrix effects had acceptable precision (coefficients of variation 2.2-12.3%). Moreover, all analytes were stable under the tested conditions. Atorvastatin lactone to acid interconversion was assessed and recommendations for its minimisation are made. The validated assay was successfully applied to analyse 1279 samples from 1024 patients recruited to a cardiovascular secondary prevention prospective study.

Platelet Function Analyzer-200 P2Y Results Are Predictive of the Risk of Major Adverse Cardiac Events in Korean Patients Receiving Clopidogrel Therapy Following Acute Coronary Syndrome

BACKGROUND

Clopidogrel is one of the most commonly used anti-platelet agents in cardiovascular diseases. We analyzed the relationship between the platelet function analyzer (PFA)-200 P2Y (INNOVANCE PFA-200 System, Siemens Healthcare, Germany) results and occurrence of major adverse cardiac events (MACEs) in Korean patients with recent-onset acute coronary syndrome (ACS) taking clopidogrel.

METHODS

Between August 2013 and June 2016, we prospectively enrolled 106 patients with recent-onset ACS who had been treated with clopidogrel. We obtained blood samples and measured closure time (CT) using the PFA-200 P2Y test. Patients were divided into two groups on the basis of a CT cut-off value of 106 seconds. We compared patient characteristics and various MACEs that occurred during the follow-up period.

RESULTS

The CTs for 78 patients exceeded the cut-off value. At the time of these analyses, 11 patients had been diagnosed with MACEs. In the time-to-event analysis, there was a difference between the two groups (P<0.001). After adjusting other variables associated with MACE occurrence, CT value was the strongest predictor of MACEs, with a 7.30-fold occurrence risk (P=0.002).

CONCLUSIONS

We found a strong relationship between CT and MACE risk in Korean patients with recent-onset ACS taking clopidogrel. Accordingly, PFA-200 P2Y results could be used as a predictive marker for MACE risk in such patients.

Impaired liver cytochrome P450 2C11 activity after dual antiplatelet therapy with aspirin and clopidogrel in rats

1. Aspirin (ASA) and clopidogrel (CLP) are used in combination as dual antiplatelet therapy (DAPT) for acute coronary syndrome based on their complementary mechanisms for platelet aggregation inhibition. However, the pharmacokinetics of such drug combination usage has not been thoroughly investigated. 2. In the current study, an LC-MS/MS method was developed to simultaneously determine the plasma concentrations of ASA and its metabolite salicylic acid (SA) with CLP and its metabolites, clopidogrel carboxylic acid (CLPM) and clopidogrel active metabolite derivative (CAMD). The pharmacokinetics of ASA, SA, CLP, CLPM and CAMD in rats receiving two-week DAPT with ASA and CLP were then determined. 3. After two-week DAPT with ASA and CLP in rats, the activities of aspirin esterase and rCyp2c11, enzymes mediating rat metabolism of ASA and CLP, respectively, in prepared rat liver microsomes were measured followed by further determination of rCyp2c11 mRNA expressions. The results demonstrated that DAPT led to minimal impact on aspirin esterase activity but significant decrease in rCyp2c11 activity and mRNA expression. 4. In conclusion, our findings on impairment in rCyp2C11 activity and mRNA expression by DAPT in rats could provide guidance on its safe clinical use with other CYP 2C19 substrates.

Aspirin Plus Clopidogrel vs Aspirin Alone for Preventing Cardiovascular Events Among Patients at High Risk for Cardiovascular Events

CLINICAL QUESTION

Among patients at high risk for or with established cardiovascular disease (ie, history of peripheral artery disease, stroke, or coronary artery disease without a coronary stent), is the addition of clopidogrel to aspirin associated with lower risk of mortality and cardiovascular events compared with aspirin alone?

BOTTOM LINE

Clopidogrel plus aspirin is associated with a reduced risk for myocardial infarction and ischemic stroke and an increased risk for major bleeding compared with aspirin alone among patients at high risk for or with an established cardiovascular disease but without a coronary stent. However, combined therapy is not associated with lower mortality.

Clopidogrel and Aspirin in Acute Ischemic Stroke and High-Risk TIA

BACKGROUND

Combination antiplatelet therapy with clopidogrel and aspirin may reduce the rate of recurrent stroke during the first 3 months after a minor ischemic stroke or transient ischemic attack (TIA). A trial of combination antiplatelet therapy in a Chinese population has shown a reduction in the risk of recurrent stroke. We tested this combination in an international population.

METHODS

In a randomized trial, we assigned patients with minor ischemic stroke or high-risk TIA to receive either clopidogrel at a loading dose of 600 mg on day 1, followed by 75 mg per day, plus aspirin (at a dose of 50 to 325 mg per day) or the same range of doses of aspirin alone. The dose of aspirin in each group was selected by the site investigator. The primary efficacy outcome in a time-to-event analysis was the risk of a composite of major ischemic events, which was defined as ischemic stroke, myocardial infarction, or death from an ischemic vascular event, at 90 days.

RESULTS

A total of 4881 patients were enrolled at 269 international sites. The trial was halted after 84% of the anticipated number of patients had been enrolled because the data and safety monitoring board had determined that the combination of clopidogrel and aspirin was associated with both a lower risk of major ischemic events and a higher risk of major hemorrhage than aspirin alone at 90 days. Major ischemic events occurred in 121 of 2432 patients (5.0%) receiving clopidogrel plus aspirin and in 160 of 2449 patients (6.5%) receiving aspirin plus placebo (hazard ratio, 0.75; 95% confidence interval [CI], 0.59 to 0.95; P=0.02), with most events occurring during the first week after the initial event. Major hemorrhage occurred in 23 patients (0.9%) receiving clopidogrel plus aspirin and in 10 patients (0.4%) receiving aspirin plus placebo (hazard ratio, 2.32; 95% CI, 1.10 to 4.87; P=0.02).

CONCLUSIONS

In patients with minor ischemic stroke or high-risk TIA, those who received a combination of clopidogrel and aspirin had a lower risk of major ischemic events but a higher risk of major hemorrhage at 90 days than those who received aspirin alone. (Funded by the National Institute of Neurological Disorders and Stroke; POINT ClinicalTrials.gov number, NCT00991029 .).

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.

Randomized Comparison of Strut Coverage between Ticagrelor and Clopidogrel in Acute Myocardial Infarction at 3-Month Optical Coherence Tomography

PURPOSE

This study aimed to compare the effects of ticagrelor and clopidogrel on early neointimal healing assessed with optical coherence tomography (OCT) after drug-eluting stent (DES) implantation in patients with acute myocardial infarction (AMI).

MATERIALS AND METHODS

AMI patients were randomly assigned to either the ticagrelor or clopidogrel arm. After DES implantation, OCT was performed to assess the percentages of uncovered struts immediately after procedure and 3 months later.

RESULTS

Due to early termination, 83 patients out of 106 initially enrolled patients (24% of planned participants) underwent 3-month OCT. Differences in vascular healing patterns between the two groups, including percentage of uncovered struts on 3-month OCT (9.6% vs. 11.7% in ticagrelor vs. clopidogrel, respectively; p=0.867), neointimal thickness, percentage of malapposed struts, and healing scores did not reach statistical significance. The predictors of uncovered strut on 3-month OCT included greater reference vessel diameter [odds ratio (OR)=1.96, p<0.001] and more malapposed struts (OR=1.12, p=0.003).

CONCLUSION

The current study did not explore favorable effect of ticagrelor on 3-month vascular healing after DES implantation. Our findings should only be considered for generating hypothesis, due to insufficient power.

Efficacy and safety of CYP2C19 genotype in stroke or transient ischemic attack patients treated with clopidogrel monotherapy or clopidogrel plus aspirin: Protocol for a systemic review and meta-analysis

BACKGROUND

The relationship of CYP2C19 genotype and clinical efficacy in stroke or transient ischemic attack (TIA) patients treated with clopidogrel monotherapy or clopidogrel plus aspirin remains unknown. We thus aim to conduct a meta-analysis to appraise evidence on the association of CYP2C19 genotype and clinical efficacy for stroke or TIA.

METHODS

An electronic search will be performed for clinical trials that reported the interested efficacy data (stroke, myocardial infarction, or vascular death) and safety data (any bleeding) in clopigogrel-treated patients with stroke or TIA. Odds ratios (ORs) with their confidence intervals (CIs) will be calculated using a meta-analysis.

RESULTS

This study will provide the evidence of the relationship between CYP2C19 genotype and clinical efficacy and safety in stroke/TIA patients taking clopidogrel by pooling the results of individual studies.

CONCLUSIONS

The results will bring about vigorous evidence in this issue and guide both clinical decision-making and future research.

Synthesis of a Novel Series of Amino Acid Prodrugs Based on Thienopyridine Scaffolds and Evaluation of Their Antiplatelet Activity

The thienopyridines class of drugs used as P2Y₁₂ receptor antagonists plays a vital role in antiplatelet therapy. To further optimized this compound class, we designed and synthesized a series of amino acid prodrugs of 2-hydroxytetrahydrothienopyridine. All compounds were then evaluated for their inhibitory effect on ADP-induced platelet aggregation in rats and then ED₅₀ and bleeding time of the most potent compounds were compared with commercial drugs. The results showed compound 5c could be a potent and safe candidate for further research.

Dual Antiplatelet Therapy for 6 Versus 18 Months After Biodegradable Polymer Drug-Eluting Stent Implantation

OBJECTIVES

The NIPPON (Nobori Dual Antiplatelet Therapy as Appropriate Duration) study was a multicenter randomized investigation of the noninferiority of short-term versus long-term dual antiplatelet therapy (DAPT) in patients with implantation of the Nobori drug-eluting stent (DES) (Terumo, Tokyo, Japan), which has a biodegradable abluminal coating.

BACKGROUND

The optimum duration of DAPT for patients with a biodegradable polymer-coated DES is unclear.

METHODS

The subjects were 3,773 patients with stable or acute coronary syndromes undergoing Nobori stent implantation. They were randomized 1:1 to receive DAPT for 6 or 18 months. The primary endpoint was net adverse clinical and cerebrovascular events (NACCE) (all-cause mortality, myocardial infarction, stroke, and major bleeding) from 6 to 18 months after stenting. Intention-to-treat analysis was performed in 3,307 patients who were followed for at least 6 months.

RESULTS

NACCE occurred in 34 patients (2.1%) receiving short-term DAPT and 24 patients (1.5%) receiving long-term DAPT (difference 0.6%, 95% confidence interval [CI]: 1.5 to 0.3). Because the lower limit of the 95% CI was inside the specified margin of -2%, noninferiority of short-term DAPT was confirmed. Mortality was 1.0% with short-term DAPT versus 0.4% with long-term DAPT, whereas myocardial infarction was 0.2% versus 0.1%, and major bleeding was 0.7% versus 0.7%, respectively. The estimated probability of NACCE was lower in the long-term DAPT group (hazard ratio: 1.44, 95% CI: 0.86 to 2.43).

CONCLUSIONS

Six months of DAPT was not inferior to 18 months of DAPT following implantation of a DES with a biodegradable abluminal coating. However, this result needs to be interpreted with caution given the open-label design and wide noninferiority margin of the present study. (Nobori Dual Antiplatelet Therapy as Appropriate Duration [NIPPON]; NCT01514227).

6- Versus 24-Month Dual Antiplatelet Therapy After Implantation of Drug-Eluting Stents in Patients Nonresistant to Aspirin: Final Results of the ITALIC Trial (Is There a Life for DES After Discontinuation of Clopidogrel)

OBJECTIVES

The aim of this study was to test the hypothesis that 6-month dual antiplatelet therapy (DAPT) is noninferior to 24-month DAPT in aspirin-sensitive patients.

BACKGROUND

The ITALIC (Is There a Life for DES After Discontinuation of Clopidogrel) trial showed that rates of bleeding and thrombotic events at 1 year were much the same with 6 versus 12 months of DAPT after percutaneous coronary intervention with second-generation drug-eluting stents. In this report, 2-year follow-up is presented.

METHODS

In a multicenter randomized study, patients with confirmed nonresistance to aspirin undergoing drug-eluting stent implantation were allocated to 6 or 24 months of DAPT. The primary endpoint was a composite of death, myocardial infarction, urgent target vessel revascularization, stroke, and major bleeding at 12 months post-percutaneous coronary intervention. The secondary endpoints comprised the same composite endpoint at 24 months and each individual component.

RESULTS

Overall, 2,031 patients from 70 centers were screened; 926 were randomized to 6-month and 924 to 24-month DAPT. Noninferiority was demonstrated for 6- versus 12-month DAPT, with an absolute risk difference of 0.11% (95% confidence interval: -1.04% to 1.26%; p = 0.0002). At 2 years, the composite endpoint was unchanged, at 3.5% for 6 months and 3.7% for 24 months (p = 0.79), and rates of myocardial infarction (1.3% vs. 1.0%; p = 0.51), stroke (0.6% vs. 0.8%; p = 0.77), and target vessel revascularization (1.0% vs. 0.3%; p = 0.09) were likewise similar. There was a trend toward higher mortality with longer DAPT (2.2% vs. 1.2%; p = 0.11). Four patients (0.4%) in the 24-month group and none in the 6-month group had major bleeding.

CONCLUSIONS

Two-year outcomes in the ITALIC trial confirmed the 1-year results and showed that patients receiving 6-month DAPT after percutaneous coronary intervention with second-generation drug-eluting stent have similar outcomes to those receiving 24-month DAPT.

Acute myocardial infarction occurring while on chronic clopidogrel therapy ('clopidogrel failure') is associated with high incidence of clopidogrel poor responsiveness and stent thrombosis

Objectives

The clinical significance of the laboratory-based phenomenon of clopidogrel hypo-responsiveness and platelet reactivity associated with acute myocardial infarction, despite chronic clopidogrel therapy, is largely unknown. We aimed to determine platelet reactivity and clinical and angiographic features in 29 consecutive patients sustaining an acute myocardial infarction despite chronic (≥1 month) clopidogrel therapy.

Methods

Platelet reactivity was determined on admission using conventional aggregometry. All patients underwent coronary angiography within 24 hours of admission. Patients were matched with clopidogrel-naïve acute myocardial infarction patients. Clopidogrel-naïve patients received a 600 mg clopidogrel loading dose and 75 mg/day thereafter.

Results

Of the 29 study patients, 19 (66%) presented with ST-elevation myocardial infarction, and in 25% the infarction was related to angiographically-proved definite stent thrombosis. Two-thirds of these patients were poor responders to clopidogrel (adenosine diphosphate-induced platelet aggregation >50%) and dual antiplatelet poor responsiveness was found in 57% in the chronic clopidogrel therapy group. Compared with clopidogrel-naïve patients, chronic clopidogrel therapy patients were more likely to demonstrate clopidogrel poor responsiveness (66% versus 38%, p = 0.02), to be diabetic (52% versus 33%, p = 0.1) and to have multi-vessel coronary disease (79% versus 55%, p = 0.03).

Conclusions

Patients sustaining acute coronary syndrome despite chronic clopidogrel therapy are more likely to exhibit inadequate platelet inhibition with clopidogrel.

Portal Vein Thrombosis in Patients With Cirrhosis Undergoing Elective Transjugular Intrahepatic Portosystemic Shunt: Risk Factors, Warfarin Efficacy, and Clinical Outcomes

Portal vein thrombosis (PVT) is a common complication in cirrhosis. The aim of this study was to determine risk factors for PVT, assess the efficacy of anticoagulant therapy, and evaluate the effects of PVT on patients with cirrhosis undergoing elective transjugular intrahepatic portosystemic shunt (TIPSS). A total of 101 patients with cirrhosis undergoing elective TIPSS were prospectively studied. After TIPSS, all patients received preventive therapy for PVT and were followed up at 3, 6, 12, and 24 months. Clinical outcomes were compared between patients who developed PVT after TIPSS and those who did not. Multivariate analysis showed that white blood cell count (relative risk [RR]: 0.377; 95% confidence interval [CI]: 0.132-0.579; P = .001), Child-Turcotte-Pugh score (RR: 1.547; 95% CI: 1.029-2.365; P = .032), and ascites (RR: 1.264; 95% CI: 1.019-1.742; P = .040) were independent predictors for PVT. Warfarin treatment within 12 months achieved significantly higher rates of complete recanalization than aspirin or clopidogrel in patients with PVT (54.5% vs 31.3%; P = .013), although adverse events were similar between the 2 groups ( P > .05). Patients without PVT had significantly lower 2-year cumulative rates of variceal rebleeding (15.9% vs 36.6%; P = .023), shunt dysfunction (27.0% vs 46.8%; P = .039), hepatic encephalopathy (24.1% vs 42.6%; P = .045), and hepatocellular carcinoma (11.4% vs 31.2%; P = .024) and markedly higher 2-year cumulative survival rates (89.8% vs 72.9%; P = .041) than those with PVT. The PVT is associated with poorer clinical outcomes in TIPSS-treated patients, and warfarin is both safe and more effective in recanalizing PVT than aspirin or clopidogrel.

6-month versus 12-month or longer dual antiplatelet therapy after percutaneous coronary intervention in patients with acute coronary syndrome (SMART-DATE): a randomised, open-label, non-inferiority trial

BACKGROUND

Current guidelines recommend dual antiplatelet therapy (DAPT) of aspirin plus a P2Y12 inhibitor for at least 12 months after implantation of drug-eluting stents (DES) in patients with acute coronary syndrome. However, available data about the optimal duration of DAPT in patients with acute coronary syndrome undergoing percutaneous coronary intervention are scant. We aimed to investigate whether a 6-month duration of DAPT would be non-inferior to the conventional 12-month or longer duration of DAPT in this population.

METHODS

We did a randomised, open-label, non-inferiority trial at 31 centres in South Korea. Patients were eligible if they had unstable angina, non-ST-segment elevation myocardial infarction, or ST-segment elevation myocardial infarction, and underwent percutaneous coronary intervention. Enrolled patients were randomly assigned, via a web-based system by computer-generated block randomisation, to either the 6-month DAPT group or to the 12-month or longer DAPT group, with stratification by site, clinical presentation, and diabetes. Assessors were masked to treatment allocation. The primary endpoint was a composite of all-cause death, myocardial infarction, or stroke at 18 months after the index procedure in the intention-to-treat population. Secondary endpoints were the individual components of the primary endpoint; definite or probable stent thrombosis as defined by the Academic Research Consortium; and Bleeding Academic Research Consortium (BARC) type 2-5 bleeding at 18 months after the index procedure. The primary endpoint was also analysed per protocol. This trial is registered with ClinicalTrials.gov, number NCT01701453.

FINDINGS

Between Sept 5, 2012, and Dec 31, 2015, we randomly assigned 2712 patients; 1357 to the 6-month DAPT group and 1355 to the 12-month or longer DAPT group. Clopidogrel was used as a P2Y12 inhibitor for DAPT in 1082 (79·7%) patients in the 6-month DAPT group and in 1109 (81·8%) patients in the 12-month or longer DAPT group. The primary endpoint occurred in 63 patients in the 6-month DAPT group and in 56 patients in the 12-month or longer DAPT group (cumulative event rate 4·7% vs 4·2%; absolute risk difference 0·5%; upper limit of one-sided 95% CI 1·8%; p_{non-inferiority}=0·03 with a predefined non-inferiority margin of 2·0%). Although all-cause mortality did not differ significantly between the 6-month DAPT group and the 12-month or longer DAPT group (35 [2·6%] patients vs 39 [2·9%]; hazard ratio [HR] 0·90 [95% CI 0·57-1·42]; p=0·90) and neither did stroke (11 [0·8%] patients vs 12 [0·9%]; 0·92 [0·41-2·08]; p=0·84), myocardial infarction occurred more frequently in the 6-month DAPT group than in the 12-month or longer DAPT group (24 [1·8%] patients vs ten [0·8%]; 2·41 [1·15-5·05]; p=0·02). 15 (1·1%) patients had stent thrombosis in the 6-month DAPT group compared with ten (0·7%) in the 12-month or longer DAPT group (HR 1·50 [95% CI 0·68-3·35]; p=0·32). The rate of BARC type 2-5 bleeding was 2·7% (35 patients) in the 6-month DAPT group and 3·9% (51 patients) in the 12-month or longer DAPT group (HR 0·69 [95% CI 0·45-1·05]; p=0·09). Results from the per-protocol analysis were similar to those from the intention-to-treat analysis.

INTERPRETATION

The increased risk of myocardial infarction with 6-month DAPT and the wide non-inferiority margin prevent us from concluding that short-term DAPT is safe in patients with acute coronary syndrome undergoing percutaneous coronary intervention with current-generation DES. Prolonged DAPT in patients with acute coronary syndrome without excessive risk of bleeding should remain the standard of care.

FUNDING

Abbott Vascular Korea, Medtronic Vascular Korea, Biosensors Inc, and Dong-A ST.

Effect of cilostazol on platelet reactivity among patients with peripheral artery disease on clopidogrel therapy

BACKGROUND

Antiplatelet therapy with clopidogrel is recommended to reduce cardiovascular events in patients with peripheral artery disease (PAD); however, clopidogrel efficacy has not been adequately studied in this patient population. Therefore, we aimed to determine the effects of cilostazol therapy on platelet reactivity among PAD patients on clopidogrel.

METHODS

We performed a cross-sectional pilot study of 46 Puerto Rican patients diagnosed with PAD. The cohort was divided based on use of clopidogrel and cilostazol (n=24) or clopidogrel alone (n=22). Platelet function was measured ex vivo using the VerifyNow P2Y12 assay. Genomic DNA was extracted from peripheral blood samples using the QIAamp DNA Blood Midi Kit, which was subjected to candidate variant genotyping (CYP2C19, ABCB1, PON1 and P2RY12) using TaqMan quantitative polymerase chain reaction assays. All analyses were performed using SAS version 9.4 (SAS Institute).

RESULTS

Among all enrolled patients, 18 (39%) had high on-treatment platelet reactivity (HTPR). The mean platelet reactivity was 207±53 (range, 78-325) with higher P2Y12 reaction units in the non-cilostazol group, 224±45 vs. 191±55 on the cilostazol group (p=0.03). No significant differences were observed in the clinical or genetic variables between the two groups. A multiple regression analysis determined that history of diabetes mellitus (p=0.03), use of cilostazol (p=0.03) and hematocrit (p=0.02) were independent predictors of platelet reactivity.

CONCLUSIONS

In Puerto Rican PAD patients on clopidogrel therapy, history of diabetes mellitus, use of cilostazol and hematocrit are independent predictors of platelet reactivity. Adjunctive cilostazol therapy may enhance clopidogrel efficacy among PAD patients with HTPR.

Panax quinquefolius saponins combined with dual antiplatelet drug therapy alleviate gastric mucosal injury and thrombogenesis through the COX/PG pathway in a rat model of acute myocardial infarction

Objectives

Previous studies have found that Panax quinquefolius saponins (PQS) combined with dual antiplatelet therapy (DAPT) of aspirin and clopidogrel enhances antithrombotic effects while reducing gastric mucosal injury induced by DAPT. We investigated the effects of the combined drug therapy (PQS+DAPT) through the COX/PG pathways.

Methods

Acute myocardial infarction (AMI) was induced in Wistar rats by ligation of the left anterior descending (LAD) coronary artery, and the animals were randomly divided into Model, DAPT, and PQS+DAPT groups. Rats in the sham group did not undergo artery ligation. They were intragastrically treated for 14 days. Myocardial infarct size; myocardial pathology; platelet aggregation rate, CD62p activation, concentrations of thromboxane B₂ (TXB₂), 6-keto-PGF1α, tissue plasminogen activator (t-PA), and plasminogen activator inhibitor (PAI), the TXB₂/6-keto-PGF1α ratio were measured. The ultrastructure of the gastric mucosa was observed by scanning electron microscopy. The expression of PGE₂ and 6-keto-PGF1α in gastric mucosa was measured by radioimmunoassay, and levels of COX-1, COX-2, and VEGF in gastric mucosa were assessed using immunohistochemistry.

Results

The addition of Panax quinquefolius saponins (PQS+DAPT) to standard DAPT therapy significantly decreased the myocardial infarct area, degree of myocardial lesions, TXB₂ and PAI levels, and the TXB₂/6-keto-PGF1α ratio, while increasing 6-keto-PGF1α and t-PA levels and reducing the degree of gastric mucosal injury. Expression of PGE₂, 6-keto-PGF1α, COX-2, and VEGF in the gastric mucosa was upregulated in the PQS+DAPT group compared with the standard DAPT group.

Conclusion

PQS increases the degree of DAPT inhibition of myocardial necrosis and antiplatelet effects in AMI rats, as well as reducing damage to the gastric mucosa caused by DAPT. The mechanism may be related to inhibition of TXB₂ and PAI activity and elevation of 6-keto-PGF1α and t-PA levels in blood, and may be associated with upregulated expression of COX-2, PGE₂, PGI₂, and VEGF in gastric tissue.

Compression force sensing regulates integrin αIIbβ3 adhesive function on diabetic platelets

Diabetes is associated with an exaggerated platelet thrombotic response at sites of vascular injury. Biomechanical forces regulate platelet activation, although the impact of diabetes on this process remains ill-defined. Using a biomembrane force probe (BFP), we demonstrate that compressive force activates integrin αIIbβ3 on discoid diabetic platelets, increasing its association rate with immobilized fibrinogen. This compressive force-induced integrin activation is calcium and PI 3-kinase dependent, resulting in enhanced integrin affinity maturation and exaggerated shear-dependent platelet adhesion. Analysis of discoid platelet aggregation in the mesenteric circulation of mice confirmed that diabetes leads to a marked enhancement in the formation and stability of discoid platelet aggregates, via a mechanism that is not inhibited by therapeutic doses of aspirin and clopidogrel, but is eliminated by PI 3-kinase inhibition. These studies demonstrate the existence of a compression force sensing mechanism linked to αIIbβ3 adhesive function that leads to a distinct prothrombotic phenotype in diabetes.

Antiplatelet therapy with aspirin, clopidogrel, and dipyridamole versus clopidogrel alone or aspirin and dipyridamole in patients with acute cerebral ischaemia (TARDIS): a randomised, open-label, phase 3 superiority trial

BACKGROUND

Intensive antiplatelet therapy with three agents might be more effective than guideline treatment for preventing recurrent events in patients with acute cerebral ischaemia. We aimed to compare the safety and efficacy of intensive antiplatelet therapy (combined aspirin, clopidogrel, and dipyridamole) with that of guideline-based antiplatelet therapy.

METHODS

We did an international, prospective, randomised, open-label, blinded-endpoint trial in adult participants with ischaemic stroke or transient ischaemic attack (TIA) within 48 h of onset. Participants were assigned in a 1:1 ratio using computer randomisation to receive loading doses and then 30 days of intensive antiplatelet therapy (combined aspirin 75 mg, clopidogrel 75 mg, and dipyridamole 200 mg twice daily) or guideline-based therapy (comprising either clopidogrel alone or combined aspirin and dipyridamole). Randomisation was stratified by country and index event, and minimised with prognostic baseline factors, medication use, time to randomisation, stroke-related factors, and thrombolysis. The ordinal primary outcome was the combined incidence and severity of any recurrent stroke (ischaemic or haemorrhagic; assessed using the modified Rankin Scale) or TIA within 90 days, as assessed by central telephone follow-up with masking to treatment assignment, and analysed by intention to treat. This trial is registered with the ISRCTN registry, number ISRCTN47823388.

FINDINGS

3096 participants (1556 in the intensive antiplatelet therapy group, 1540 in the guideline antiplatelet therapy group) were recruited from 106 hospitals in four countries between April 7, 2009, and March 18, 2016. The trial was stopped early on the recommendation of the data monitoring committee. The incidence and severity of recurrent stroke or TIA did not differ between intensive and guideline therapy (93 [6%] participants vs 105 [7%]; adjusted common odds ratio [cOR] 0·90, 95% CI 0·67-1·20, p=0·47). By contrast, intensive antiplatelet therapy was associated with more, and more severe, bleeding (adjusted cOR 2·54, 95% CI 2·05-3·16, p<0·0001).

INTERPRETATION

Among patients with recent cerebral ischaemia, intensive antiplatelet therapy did not reduce the incidence and severity of recurrent stroke or TIA, but did significantly increase the risk of major bleeding. Triple antiplatelet therapy should not be used in routine clinical practice.

FUNDING

National Institutes of Health Research Health Technology Assessment Programme, British Heart Foundation.

Enzyme Kinetics and Molecular Docking Studies on Cytochrome 2B6, 2C19, 2E1, and 3A4 Activities by Sauchinone

Sauchinone, an active lignan isolated from the aerial parts of Saururus chinensis (Saururaceae), exhibits anti-inflammatory, anti-obesity, anti-hyperglycemic, and anti-hepatic steatosis effects. As herb–drug interaction (HDI) through cytochrome P450s (CYPs)-mediated metabolism limits clinical application of herbs and drugs in combination, this study sought to explore the enzyme kinetics of sauchinone towards CYP inhibition in in vitro human liver microsomes (HLMs) and in vivo mice studies and computational molecular docking analysis. In in vitro HLMs, sauchinone reversibly inhibited CYP2B6, 2C19, 2E1, and 3A4 activities in non-competitive modes, showing inhibition constant (K_i) values of 14.3, 16.8, 41.7, and 6.84 μM, respectively. Also, sauchinone time-dependently inhibited CYP2B6, 2E1 and 3A4 activities in vitro HLMs. Molecular docking study showed that sauchinone could be bound to a few key amino acid residues in the active site of CYP2B6, 2C19, 2E1, and 3A4. When sibutramine, clopidogrel, or chlorzoxazone was co-administered with sauchinone to mice, the systemic exposure of each drug was increased compared to that without sauchinone, because sauchinone reduced the metabolic clearance of each drug. In conclusion, when sauchinone was co-treated with drugs metabolized via CYP2B6, 2C19, 2E1, or 3A4, sauchinone–drug interactions occurred because sauchinone inhibited the CYP-mediated metabolic activities.

Aspirin plus dipyridamole has the highest surface under the cumulative ranking curves (SUCRA) values in terms of mortality, intracranial hemorrhage, and adverse event rate among 7 drug therapies in the treatment of cerebral infarction

BACKGROUND

The standardization for the clinical use of drug therapy for cerebral infarction (CI) has not yet determined in some aspects. In this paper, we discussed the efficacies of different drug therapies (aspirin, aspirin plus dipyridamole, aspirin plus clopidogrel, aspirin plus warfarin, cilostazol, warfarin, and ticlopidine) for CI.

METHODS

We searched databases of PubMed and Cochrane Library from the inception to April, 2017, randomized controlled trials (RCTs) met the inclusion and exclusion criteria were enrolled in this study. The network meta-analysis integrated evidences of direct and indirect comparisons to assess odd ratios (OR) and surface under the cumulative ranking curves (SUCRA) value.

RESULTS

Thirteen eligible RCTs including 7 drug therapies were included into this network meta-analysis. The network meta-analysis results showed that CI patients who received aspirin plus dipyridamole presented lower mortality when compared with those received aspirin plus clopidogrel (OR = 0.46, 95% CI = 0.18-0.99), indicating aspirin plus dipyridamole therapy had better efficacy for CI. As for intracranial hemorrhage (ICH), stroke recurrence, and adverse event (AE) rate, there were no significant differences of efficacy among 7 drug therapies. Besides, SUCRA values demonstrated that in the 7 drug therapies, aspirin plus dipyridamole therapy was more effective than others (mortality: 80.67%; ICH: 76.6%; AE rate: 90.2%).

CONCLUSIONS

Our findings revealed that aspirin plus dipyridamole therapy might be the optimum one for patients with CI, which could help to improve the survival of CI patients.

The Prognostic Value of Combinations of Genetic Polymorphisms in the ITGB3, ITGA2, and CYP2C19*2 Genes in Predicting Cardiovascular Outcomes After Coronary Bypass Grafting

AIM

To determine if there are any associations between the single nucleotide polymorphisms (SNPs): rs2046934, rs1126643, rs5918, rs6065, rs4244285; rs4986893 and the occurrence of cardiovascular events (CVE) in patients following coronary artery bypass grafting (CABG) surgery.

MATERIALS AND METHODS

The study included 130 CABG patients with stable angina grades II-IV. After CABG 69 of the patients were treated with acetylsalicylic acid (ASA) alone, and 61 received dual antiplatelet therapy (ASA+clopidogrel). Platelet function was assessed by light transmission aggregometry with adenosinediphosphate and arachidonic acid. The SNPs were identified by real-time polymerase chain reaction (PCR) with electrophoretic detection. The mean follow-up period was equal to 10.9 ± 5.2 months. The primary end point included the composite of all-cause mortality, myocardial infarction (MI), and ischemic stroke.

RESULTS

During the follow-up period 12 CVE were registered: 3 deaths, 6 MI, 3 strokes. Patients with composite mutant alleles of ITGB3+CYP2C19*2 or CYP2C19*2 + ITGA2, and with the mutant allele (*2) of CYP2C19, met end points more often than patients with other gene combinations (wild-type homozygotes, presence of one mutant allele of ITGB3 or ITGA2, the composite of mutant alleles of ITGB3+ITGA2 or ITGB3+ITGA2+CYP2C19*2; hazard ratio = 4, 95% confidence interval: 2.19-7.29, p = 0.008).

CONCLUSION

Carriage of a combination of mutant alleles in multiple genes including ITGB3+CYP2C19*2 or CYP2C19*2 + ITGA2 or CYP2C19*2 are possible predictors of CVE in patients after CABG.

CYP2C19 and ABCB1 genetic polymorphisms correlate with the recurrence of ischemic cardiovascular adverse events after clopidogrel treatment

BACKGROUND

This study was aimed to investigate the correlation between CYP2C19 and ABCB1 polymorphisms and the recurrence of ischemic cardiovascular adverse events in patients with coronary artery disease treated with clopidogrel.

METHODS

A total of 168 patients with coronary heart disease who underwent PCI operation and received clopidogrel treatment were enrolled. Dual antiplatelet therapy was applied to the treatment of patients for 2 years. Thromboelastography was used to test the efficiency of blood coagulation. Polymerase chain reaction (PCR) was used to detect CYP2C19 and ABCB1 3435CT polymorphisms. One-year follow-up visit was carried out to record the incidence of cardiovascular adverse events after drug-eluting stent implantation was inset.

RESULTS

Follow-up visit results suggested that the patients with high on-treatment platelet reactivity (HPR) had a higher recurrence rate of cardiovascular adverse events after PCI operation and clopidogrel treatment. Gene polymorphism testing results indicated that patients with CYP2C19*3 had a significantly higher incidence of HPR, whereas CYP2C19*2 and ABCB1 3435CT were not significantly correlated with HPR. Multivariable logistic regression analysis showed that CYP2C19*3 might be an independent predictive factor of post-PCI HPR. In addition, CYP2C19*3 as well as post-PCI HPR could function as independent predictive factors of cardiovascular adverse events.

CONCLUSION

CYP2C19*3 polymorphism could be an important predictive factor of HPR and ischemic cardiovascular adverse events after clopidogrel treatment.

Role of genetic testing in patients undergoing percutaneous coronary intervention

INTRODUCTION

Variability in individual response profiles to antiplatelet therapy, in particular clopidogrel, is a well-established phenomenon. Genetic variations of the cytochrome P450 (CYP) 2C19 enzyme, a key determinant in clopidogrel metabolism, have been associated with clopidogrel response profiles. Moreover, the presence of a CYP2C19 loss-of-function allele is associated with an increased risk of atherothrombotic events among clopidogrel-treated patients undergoing percutaneous coronary interventions (PCI), prompting studies evaluating the use of genetic tests to identify patients who may be potential candidates for alternative platelet P2Y12 receptor inhibiting therapies (prasugrel or ticagrelor). Areas covered: The present manuscript provides an overview of genetic factors associated with response profiles to platelet P2Y12 receptor inhibitors and their clinical implications, as well as the most recent developments and future considerations on the role of genetic testing in patients undergoing PCI. Expert commentary: The availability of more user-friendly genetic tests has contributed towards the development of many ongoing clinical trials and personalized medicine programs for patients undergoing PCI. Results of pilot investigations have shown promising results, which however need to be confirmed in larger-scale studies to support the routine use of genetic testing as a strategy to personalize antiplatelet therapy and improve clinical outcomes.

Time trends in peripheral artery disease incidence, prevalence and secondary preventive therapy: a cohort study in The Health Improvement Network in the UK

OBJECTIVES

To assess time trends in symptomatic peripheral artery disease (PAD) incidence and prevalence, and secondary preventive therapy.

DESIGN

Cohort study using The Health Improvement Network.

SETTING

UK primary care.

PARTICIPANTS

Individuals aged 50-89 years identified annually between 2000 and 2014. Participants with symptomatic PAD were identified using Read codes.

OUTCOME MEASURES

Incidence and prevalence of symptomatic PAD from 2000 to 2014, overall and by sex and age. Proportion of patients prescribed secondary preventive therapy with acetylsalicylic acid (ASA), clopidogrel, an ACE inhibitor, an angiotensin receptor blocker (ARB) and/or a statin.

RESULTS

The incidence of symptomatic PAD per 10 000 person-years decreased over time, from 38.6 (men: 51.0; women: 28.7) in 2000 to 17.3 (men: 23.1; women: 12.4) in 2014. The prevalence of symptomatic PAD decreased from 3.4% (men: 4.5%; women: 2.5%) in 2000 to 2.4% (men: 3.1%; women: 1.7%) in 2014. Incidence and prevalence decreases were observed in all age groups. The proportions of patients prescribed ASA monotherapy, clopidogrel monotherapy and dual antiplatelet therapy in the 2 months after PAD diagnosis were 42.7%, 2.9% and 2.5%, respectively, during 2000-2003, and 44.7%, 11.0% and 5.2%, respectively, during 2012-2014. For ACE inhibitor/ARB therapy and statins, proportions in the 2 months after diagnosis were 30.2% and 31.2%, respectively, during 2000-2003, and 45.1% and 65.9%, respectively, during 2012-2014.

CONCLUSION

The incidence and prevalence of symptomatic PAD diagnosed in UK primary care are decreasing. A large proportion of the population with PAD in clinical practice does not receive guideline-recommended secondary prevention therapy.

A complementary role for tetraspanin superfamily member TSSC6 and ADP purinergic P2Y12 receptor in platelets

Tumor-suppressing subchromosomal transferable fragment cDNA 6 (TSSC6) expression is restricted to hematopoietic organs and tissues where it plays a role in hematopoietic-cell function. The ADP purinergic receptor P2Y12 is mainly expressed by platelets with important clinical significance as a target for several clinically approved antithrombotic agents. We have previously shown a physical association between P2Y12 and TSSC6 in platelets. Hence our aim was to investigate whether this physical association is translated to functional effects. To investigate this possibility, we used wild-type or TSSC6 knockout (KO) mice treated with either PBS or 50mg/kg clopidogrel. TSSC6 KO mice treated with clopidogrel exhibited synergy in delayed kinetics of clot retraction, reduced collagen-mediated platelet aggregation, and platelet spreading on fibrinogen. Platelets derived from TSSC6 mice with P2Y12 blockade form smaller thrombi when perfused over a collagen matrix under arterial flow. Clopidogrel treated TSSC6 KO arterioles showed smaller and less stable thrombi with increased tendency to embolise in vivo. These studies demonstrate a complementary role between TSSC6 and P2Y12 receptor in platelets in regulating 'outside in' integrin αIIbβ3 signalling thrombus growth and stability.

Comparison of Multiplate, Platelet Function Analyzer-200, and Plateletworks in Healthy Dogs Treated with Aspirin and Clopidogrel

BACKGROUND

Platelet function testing may be warranted to assess response to aspirin and clopidogrel.

HYPOTHESIS/OBJECTIVES

To evaluate the effects of aspirin, clopidogrel, or combination therapy using 3 platelet function tests: Multiplate Analyzer (MP), Platelet Function Analyzer-200 (PFA), and Plateletworks (PW).

ANIMALS

Six healthy laboratory Beagles.

METHODS

Randomized double-blind placebo-controlled study (crossover design). Dogs were given aspirin 1 mg/kg, clopidogrel 2 mg/kg, or combination therapy for 1 week each, with a washout period of 2 weeks. Platelet function was assessed on days 0 and 7 of each phase using MP (adenosine diphosphate [ADP], arachidonic acid [AA], collagen [COL] agonists), PFA (P2Y, COL-ADP [CADP], COL-Epinephrine [CEPI] cartridges), and PW (ADP, AA, COL agonists). Platelet counts were obtained with impedance and optical counters.

RESULTS

For MP, mean aggregation was decreased for COL and AA with combination therapy and for ADP with all treatments. For PFA, mean CT was increased for the CEPI cartridge with aspirin; and for the P2Y and CADP cartridges with clopidogrel or combination therapy. More dogs receiving clopidogrel showed an increase in PFA CT using the P2Y than the CADP cartridge. For PW, mean aggregation was decreased for AA with all treatments; for ADP with clopidogrel or combination therapy; and for COL with clopidogrel. The PW results with the 2 hematology counters showed almost perfect agreement.

CONCLUSION AND CLINICAL IMPORTANCE

All platelet function tests detected treatment effects in some dogs and may have utility for monitoring therapy.

Influence of proton pump inhibitors on clinical outcomes in coronary heart disease patients receiving aspirin and clopidogrel: A meta-analysis

BACKGROUND

Proton pump inhibitors (PPIs) are usually prescribed to protect against gastrointestinal bleeding in patients on dual antiplatelet therapy. This meta-analysis reviewed clinical outcomes in patients taking aspirin and clopidogrel, with and without concomitant PPIs to address concerns of adverse reactions.

METHODS

We searched PubMed, Embase, and the Cochrane Library for articles published between January 1, 2010 and April 11, 2017. The primary end points were major adverse cardiovascular events and gastrointestinal bleeding. Secondary end points were myocardial infarction, stent thrombosis, revascularization, cardiogenic death, and all-cause mortality.

RESULTS

The meta-analysis included 33,492 patients in 4 randomized controlled trials and 8 controlled observational studies. Overall, patients taking PPIs had statistical differences in major adverse cardiovascular events [odds ratio (OR) 1.17 (95% confidence interval [CI] 1.07-1.28); P = .001; I = 28.3%], gastrointestinal bleeding [OR 0.58 (95% CI 0.36-0.92); P = .022; I = 80.6%], stent thrombosis [OR 1.30 (95% CI 1.01-1.68); P = .041; I = 0%], and revascularization [OR 1.20 (95% CI 1.04-1.38); P = .011; I = 5.1%], compared those not taking PPIs. There were no significant differences in myocardial infarction [OR 1.03 (95% CI 0.87-1.22); P = .742; I = 0%], cardiogenic death [OR 1.09 (95% CI 0.83-1.43); P = .526; I = 0%], or all-cause mortality [OR 1.08 (95% CI 0.93-1.25); P = .329; I = 0%).

CONCLUSIONS

Among the patients taking aspirin and clopidogrel, the results indicated that the combined use of PPIs increased the rates of major adverse cardiovascular events, stent thrombosis, and revascularization.

Clopidogrel plus aspirin versus aspirin alone for preventing cardiovascular events

BACKGROUND

Aspirin is the prophylactic antiplatelet drug of choice for people with cardiovascular disease. Adding a second antiplatelet drug to aspirin may produce additional benefit for people at high risk and people with established cardiovascular disease. This is an update to a previously published review from 2011.

OBJECTIVES

To review the benefit and harm of adding clopidogrel to aspirin therapy for preventing cardiovascular events in people who have coronary disease, ischaemic cerebrovascular disease, peripheral arterial disease, or were at high risk of atherothrombotic disease, but did not have a coronary stent.

SEARCH METHODS

We updated the searches of CENTRAL (2017, Issue 6), MEDLINE (Ovid, 1946 to 4 July 2017) and Embase (Ovid, 1947 to 3 July 2017) on 4 July 2017. We also searched ClinicalTrials.gov and the WHO ICTRP portal, and handsearched reference lists. We applied no language restrictions.

SELECTION CRITERIA

We included all randomised controlled trials comparing over 30 days use of aspirin plus clopidogrel with aspirin plus placebo or aspirin alone in people with coronary disease, ischaemic cerebrovascular disease, peripheral arterial disease, or at high risk of atherothrombotic disease. We excluded studies including only people with coronary drug-eluting stent (DES) or non-DES, or both.

DATA COLLECTION AND ANALYSIS

We collected data on mortality from cardiovascular causes, all-cause mortality, fatal and non-fatal myocardial infarction, fatal and non-fatal ischaemic stroke, major and minor bleeding. The overall treatment effect was estimated by the pooled risk ratio (RR) with 95% confidence interval (CI), using a fixed-effect model (Mantel-Haenszel); we used a random-effects model in cases of moderate or severe heterogeneity (I2 ≥ 30%). We assessed the quality of the evidence using the GRADE approach. We used GRADE profiler (GRADE Pro) to import data from Review Manager to create a 'Summary of findings' table.

MAIN RESULTS

The search identified 13 studies in addition to the two studies in the previous version of our systematic review. Overall, we included data from 15 trials with 33,970 people. We completed a 'Risk of bias' assessment for all studies. The risk of bias was low in four trials because they were at low risk of bias for all key domains (random sequence generation, allocation concealment, blinding, selective outcome reporting and incomplete outcome data), even if some of them were funded by the pharmaceutical industry.Analysis showed no difference in the effectiveness of aspirin plus clopidogrel in preventing cardiovascular mortality (RR 0.98, 95% CI 0.88 to 1.10; participants = 31,903; studies = 7; moderate quality evidence), and no evidence of a difference in all-cause mortality (RR 1.05, 95% CI 0.87 to 1.25; participants = 32,908; studies = 9; low quality evidence).There was a lower risk of fatal and non-fatal myocardial infarction with clopidogrel plus aspirin compared with aspirin plus placebo or aspirin alone (RR 0.78, 95% CI 0.69 to 0.90; participants = 16,175; studies = 6; moderate quality evidence). There was a reduction in the risk of fatal and non-fatal ischaemic stroke (RR 0.73, 95% CI 0.59 to 0.91; participants = 4006; studies = 5; moderate quality evidence).However, there was a higher risk of major bleeding with clopidogrel plus aspirin compared with aspirin plus placebo or aspirin alone (RR 1.44, 95% CI 1.25 to 1.64; participants = 33,300; studies = 10; moderate quality evidence) and of minor bleeding (RR 2.03, 95% CI 1.75 to 2.36; participants = 14,731; studies = 8; moderate quality evidence).Overall, we would expect 13 myocardial infarctions and 23 ischaemic strokes be prevented for every 1000 patients treated with the combination in a median follow-up period of 12 months, but 9 major bleeds and 33 minor bleeds would be caused during a median follow-up period of 10.5 and 6 months, respectively.

AUTHORS' CONCLUSIONS

The available evidence demonstrates that the use of clopidogrel plus aspirin in people at high risk of cardiovascular disease and people with established cardiovascular disease without a coronary stent is associated with a reduction in the risk of myocardial infarction and ischaemic stroke, and an increased risk of major and minor bleeding compared with aspirin alone. According to GRADE criteria, the quality of evidence was moderate for all outcomes except all-cause mortality (low quality evidence) and adverse events (very low quality evidence).

Nitroaspirin plus clopidogrel versus aspirin plus clopidogrel against platelet thromboembolism and intimal thickening in mice

Clopidogrel plus aspirin is the treatment of choice for patients undergoing percutaneous, coronary interventions with stenting, but it does not prevent restenosis. NCX-4016, a nitric oxide-releasing aspirin (nitroaspirin), exerts a wider range of antiplatelet actions compared to aspirin, superior antithrombotic activity and reduces restenosis after arterial injury in animals. The aim of the present study was to compare the combination of nitroaspirin plus clopidogrel with aspirin plus clopidogrel in a model of platelet pulmonary thromboembolism, bleeding and intimal thickening in mice. Drugs were administered orally for 5 days; the antithrombotic effects were evaluated against collagen plus epinephrine-induced pulmonary thromboembolism, the haemorrhagic effects by tail transection bleeding time and the effects on neointima proliferation by histomorphology of photochemically injured femoral arteries. Lung platelet emboli were reduced significantly and more effectively by nitroaspirin plus clopidogrel (-56%, p< 0.05 vs control) than by aspirin plus clopidogrel (-26%, p< 0.05 vs control). Ex vivo platelet aggregation was inhibited maximally by nitroaspirin plus clopidogrel. Aspirin plus clopidogrel strikingly prolonged the bleeding time while nitroaspirin plus clopidogrel induced a lesser prolongation. Nitroaspirin plus clopidogrel significantly reduced intimal thickening of the femoral artery while aspirin plus clopidogrel was ineffective. Nitroaspirin plus clopidogrel is more effective and less prohaemorrhagic than aspirin plus clopidogrel in mice; provided these data are confirmed in other animal models, nitroaspirin plus clopidogrel may represent a new regimen to be tested in patients undergoing coronary revascularization procedures.

Clopidogrel in a combined therapy with anticancer drugs-effect on tumor growth, metastasis, and treatment toxicity: Studies in animal models

Clopidogrel, a thienopyridine derivative with antiplatelet activity, is widely prescribed for patients with cardiovascular diseases. In addition to antiplatelet activity, antiplatelet agents possess anticancer and antimetastatic properties. Contrary to this, results of some studies have suggested that the use of clopidogrel and other thienopyridines accelerates the progression of breast, colorectal, and prostate cancer. Therefore, in this study, we aimed to evaluate the efficacy of clopidogrel and various anticancer agents as a combined treatment using mouse models of breast, colorectal, and prostate cancer. Metastatic dissemination, selected parameters of platelet morphology and biochemistry, as well as angiogenesis were assessed. In addition, body weight, blood morphology, and biochemistry were evaluated to test toxicity of the studied compounds. According to the results, clopidogrel increased antitumor and/or antimetastatic activity of chemotherapeutics such as 5-fluorouracil, cyclophosphamide, and mitoxantrone, whereas it decreased the anticancer activity of doxorubicin, cisplatin, and tamoxifen. The mechanisms of such divergent activities may be based on the modulation of tumor vasculature via factors, such as transforming growth factor β1 released from platelets. Moreover, clopidogrel increased the toxicity of docetaxel and protected against mitoxantrone-induced toxicity, which may be due to the modulation of hepatic enzymes and protection of the vasculature, respectively. These results demonstrate that antiplatelet agents can be useful but also dangerous in anticancer treatment and therefore use of thienopyridines in patients undergoing chemotherapy should be carefully evaluated.

Pharmacological properties of YM-254890, a specific Gαq/11 inhibitor, on thrombosis and neointima formation in mice

The pharmacological properties of YM-254890,a specific Gαq/11 inhibitor, on acute thrombosis and chronic neointima formation after vascular injury have been investigated. FeCl3 was used to induce vascular injury in the carotid artery of mice. For the thrombosis studies, the test drug was either intravenously or orally administered before vascular injury. For the neointima studies, the test drug was orally administered 1 h before and twice daily for 1 week after vascular injury. Histological analysis was then performed 3 weeks later. YM-254890 significantly inhibited ex vivo platelet aggregation 5 min after intravenous bolus injection at 0.03 mg/kg or more, and 1 h after oral administration at 1 mg/kg. YM-254890 significantly inhibited thrombus formation after intravenous bolus injection at 0.03 mg/kg as well as after oral administration at 1 mg/kg, but tail transection bleeding time was significantly prolonged at 0.1 mg/kg for intravenous injection and 3 mg/kg for oral administration. Furthermore, oral administration of YM-254890 dose-dependently inhibited neointima formation 3 weeks after vascular injury with significant effects at 1 mg/kg twice daily for 1 week. Clopidogrel also significantly inhibited neointima formation at its antithrombotic dose, but its inhibitory potency was less than that of YM-254890. However, YM-254890 significantly reduced systemic blood pressure at doses 3 times higher than those that produced significant inhibitory effects on thrombosis and neointima formation. Though the systemic use of YM-254890 may be limited, owing to its narrow therapeutic window, this unique compound is a useful research tool for investigating the physiological roles of Gαq/11.

Comparison of two methods to assess variability of platelet response to anti-platelet therapies in patients with acute coronary syndrome undergoing angioplasty

The study investigated the clinical usefulness of a new method to evaluate platelet activation and the variability of platelet response to anti-platelet therapy in patients undergoing percutaneous transluminal coronary angioplasty (PTCA). Platelet activation was assessed in parallel by a new method for platelet density measurements (MPC, Mean Platelet Component Concentration), on the automated ADVIA 120 Hematology System and by the classic measurement of P-selectin (CD62P) expression, on a fluorescence flow cytometer. Patients received a loading dose of clopidogrel (300 mg; n = 29) or a bolus of abciximab (0.25 mg/kg; n = 15). Blood samples were collected before (baseline) and at different times after PTCA and antiplatelet drugs administration. Our data showed a close inverse correlation between the change in MPC and the CD62P fluorescence surface marker expression (r = 0.776, P<0.0001). Individual platelet activation determinations in patients receiving either clopidogrel or abciximab showed a variation in platelet activation as assayed by MPC and CD62P expression. Patients were characterized as having either high platelet activity upon admission and positive response to treatment or no detectable platelet activation before or after treatment. This study demonstrates the heterogeneity of platelet activation states in ACS patients undergoing coronary angioplasty. The present work also illustrates the potential use of the MPC parameter, generated on an automated hematology system, to define high risk patients and to monitor the variability of platelet response to anti-platelet therapies.

Comparison between ticlopidine and clopidogrel in patients with ST-segment elevation myocardial infarction treated with coronary stenting

Controversy still surrounds the question, which antiplatelet drug should be added to aspirin in patients undergoing coronary stent implantation. The aim of the current study was to compare ticlopidine and clopidogrel in a consecutive series of patients with ST-segment elevation myocardial infarction (STEMI) treated with primary stenting. Our population is represented by 883 consecutive patients with STEMI undergoing primary stenting from April 1997 to October 2001. All clinical, angiographic, and follow-up data were prospectively collected. A total of 523 patients on clopidogrel were compared with 360 patients on ticlopidine after primary stenting. Except for age and statin therapy, no difference in demographic and clinical characteristics was observed between the two groups. Patients on clopidogrel had a higher rate of successful reperfusion (80.7% vs 73.1%, p = 0.008). No difference was observed between the two groups at both 30-day and 1-year follow-up. These data were confirmed after correction for age, successful reperfusion and statin therapy. This study shows no difference in long-term clinical outcome between clopidogrel and ticlopidine as adjunctive antiplatelet therapy in patients with STEMI undergoing stent implantation.

Influence of genetic co-factors on the population pharmacokinetic model for clopidogrel and its active thiol metabolite

PURPOSE

A high interindividual variability is observed in the pharmacokinetics of clopidogrel, a widely used antiplatelet drug. In the present study, a joint parent-metabolite population pharmacokinetic model was developed to adequately describe observed concentrations of clopidogrel and its active thiol metabolite (H4).

METHODS

The study included 63 patients undergoing elective coronarography or percutaneous coronary intervention. The population pharmacokinetic model was developed in the NONMEM 7.3 software, and first-order conditional estimation method with interaction was applied. Also, the influence of covariates was evaluated (age, weight, body mass index (BMI), obesity defined as BMI ≥ 30 kg/m2, sex, diabetes mellitus, co-administration of PPI or statins, presence of CYP2C19*2, CYP2C19*17, CYP3A4*1G alleles, and ABCB1 3435 TT genotype).

RESULTS

It was found that the only significant covariate was the presence of CYP2C19*2 allele, which had an impact on lower conversion of clopidogrel to H4. As a result, predicted area under the time-concentration curve values was lower in carriers of this allele, with median 5.94 ng h/ml (interquartile range 3.92-12.51 [ng∙h/ml]) vs. 12.70 ng h/ml in non-carriers (interquartile range, 7.00-19.39 [ng∙h/ml]), respectively (p = 0.004).

CONCLUSIONS

Developed model predicts that the only significant covariate influencing the observed concentrations and therefore the exposure to the active H4 metabolite is the presence of CYP2C19*2 allele.

Pharmacologic inhibition of platelet vWF-GPIbα interaction prevents coronary artery thrombosis

Under high shear arterial blood flow von Willebrand Factor (vWF) binds the platelet receptor glycoprotein (GP) Ibα, leading to platelet adhesion, activation and thrombosis. Blockade of vWF-GPIbα interactions by GPG-290 was investigated in a canine model of coronary artery thrombosis alone and in combination with clopidogrel. GPG-290 (100 µg/kg, n=6; 500 µg/kg, n=6) prolonged time to thrombotic occlusion (TTO) to 105±34 and 156±23 (p<0.05) min, respectively compared to the saline treated control group (32±6min, n=6). Patency of the injured vessel was sustained in 1/6 (100µg/kg) and 3/6 vessels (500 µg/kg) 4 hours after injury, in contrast to 0/6 in the control group. There was an increase in bleeding after the 500 µg/kg dose, but only at the 1 hr time point. Clopidogrel was studied in two dosing regimens representing either a clinical pretreatment regimen (PTR) of 4.3 mg/kg on day –2 followed by 1.1 mg/kg daily for2 days prior to the procedure or pre-procedural loading dose regimen (LDR) of 4.3 mg/kg 3 hr pre-procedure. The PTR and LDR clopidogrel treatments prolonged TTO to 98.2±30.0 min and 136.1±39.5 min (p<0.05), and sustained patency in 1/6 and 4/8 vessels, respectively. However, template bleeding time in the LDR clopidogrel group was sustained higher than the control group. The combination of PTR clopidogrel and GPG-290 (100 µg/kg) prolonged TTO equivalent to LDR clopidogrel alone (141.4±35.1 min) and sustained patency in 3/7 dogs, without increased bleeding while LDR clopidogrel combined with 100 µg/kg GPG-290 prevented occlusion in 5/8 dogs and further prolonged TTO (173.5±32.6 min) but was associated with increased bleeding compared to control. GPG-290 is an antithrombotic agent that may be combined with lower doses of clopidogrel to yield similar antithrombotic efficacy as higher loading doses.

Pre-treatment with clopidogrel and postprocedure troponin elevation after elective percutaneous coronary intervention

Elevated troponin after elective percutaneous coronary intervention (PCI) has been associated with a worse prognosis. Pretreatment with clopidogrel may be beneficial in patients undergoing PCI. Therefore, a prospective observational study was conducted to address the potential role of clopidogrel in reducing troponin release after elective PCI. TroponinT was measured 12 hours after elective PCI in 656 patients without elevated troponin before PCI. To assess the independent association between pre-treatment with clopidogrel and increased troponin, multivariate analyses were performed. Mean age of the 656 patients was 63.5 years (SD 10.2), 194 patients (30%) were female and 114 patients (17.4%) had diabetes. In 217 patients (33%) troponin was increased after PCI. Of the 330 patients who were not pre-treated with clopidogrel, 118 patients (34%) had increased troponin after the PCI compared to 99 patients (30%) of the 326 patients who were treated with clopidogrel longer than 24 hours before the procedure (p=0.14). Stratified analyses showed that patients with older age (p=0.03), previous PCI (p=0.013), angina CCS 4 (p=0.03) and multivessel disease (p=0.04) had a significantly lower risk of troponin increase after pre-treatment with clopidogrel compared to patients without pre-treatment. After adjusting for differences in the other variables, patients who were pre-treated with clopidogrel had a significant lower risk of post-PCI increase of troponinT (odds ratio 0.69, 95% confidence interval 0.49–0.99). Pre-treatment with clopidogrel is associated with a significantly lower incidence of increased troponin after elective PCI. Combined with results of other studies, pre-treatment should be advised in patients waiting for elective PCI.