Activity Of Clopidogrel Research Articles

Limited visibility and uptake of the clopidogrel pharmacogenomic guidelines among cardiologists

Abstract Background Clopidogrel is an antiplatelet agent widely utilised in the treatment of acute coronary syndromes and following coronary interventions. Clopidogrel is a prodrug activated in the liver, mostly by cytochrome P450 2C19 that is encoded by a gene (CYP2C19). Variability in CYPC2C19 affects enzymatic activity and leads to variability in the activation and efficacy of clopidogrel. In 2011, the Clinical Pharmacogenetics Implementation Consortium (CPIC) produced the first set of detailed guidelines on the use of genetic testing to guide the clinical utilization of clopidogrel. Updates on these guidelines were published in 2013 and 2022. However, pre-prescription genetic testing is seldom performed. Purpose To establish whether these pharmacogenomics guidelines have visibility within the cardiovascular (CVD)community and have been incorporated into CVD guidelines. Methods (i) We examine the impact of the CPIC Clopidogrel guidelines released in 2013 and 2022 by looking at the citation patterns in CVD journals indexed in PubMed. (ii) We reviewed the guidelines released by the European Society of Cardiology and the American College of Cardiology on the management of coronary interventions and coronary artery disease over the last 15 years to establish whether CPIC guidelines are making any impact on practice. Results The CPIC 2022 guidelines were cited by 88 articles (49 journals) of which 13 citations (14.7%) appear in CVD journals. None of these citations are in the five major journals in which CVD guideline statements are most frequently published (Nature Review Cardiology, European Heart Journal, Circulation, Journal of the American College of Cardiology, and Journal of the American Medical Association - Cardiology). The 2013 guideline received 366 citations (183 PubMed journals). Of these, 47 were in cardiology journals (12.8%), but only 4 citations were in one of the same five major cardiology journals (2 in Nature Review Cardiology, 1 in Circulation and 1 in JAMA Cardiology). Of the 14 guidelines published by the ESC and ACC over the last 14 years, none cited the CPIC clopidogrel guidelines. Only 6 out of the 14 guidelines mentioned that the efficacy of clopidogrel was modulated by genetic factors but none of them included details or practical implications. Conclusion(s) Whilst sufficient time has not yet elapsed for the 2022 CPIC guidelines to have an impact on the specialist literature, the 2013 guidelines have had limited visibility within the CVD community. Undoubtedly, given the potential contribution of PGx, discussions on its uptakes are ongoing thus far, without resolution. Some considerations of clopidogrel genetics are diffusing into the specialty; however, from the citation evidence, it appears that CPIC clopidogrel guidelines of any vintage have had limited impact in terms of adoption and/or endorsement by cardiologists.

Molecular genomic and epigenomic characteristics related to aspirin and clopidogrel resistance

BackgroundMediators, genomic and epigenomic characteristics involving in metabolism of arachidonic acid by cyclooxygenase (COX) and lipoxygenase (ALOX) and hepatic activation of clopidogrel have been individually suggested as factors associated with resistance against aspirin and clopidogrel. The present multi-center prospective cohort study evaluated whether the mediators, genomic and epigenomic characteristics participating in arachidonic acid metabolism and clopidogrel activation could be factors that improve the prediction of the aspirin and clopidogrel resistance in addition to cardiovascular risks.MethodsWe enrolled 988 patients with transient ischemic attack and ischemic stroke who were evaluated for a recurrence of ischemic stroke to confirm clinical resistance, and measured aspirin (ARU) and P2Y12 reaction units (PRU) using VerifyNow to assess laboratory resistance 12 weeks after aspirin and clopidogrel administration. We investigated whether mediators, genotypes, and promoter methylation of genes involved in COX and ALOX metabolisms and clopidogrel activation could synergistically improve the prediction of ischemic stroke recurrence and the ARU and PRU levels by integrating to the established cardiovascular risk factors.ResultsThe logistic model to predict the recurrence used thromboxane A synthase 1 (TXAS1, rs41708) A/A genotype and ALOX12 promoter methylation as independent variables, and, improved sensitivity of recurrence prediction from 3.4% before to 13.8% after adding the mediators, genomic and epigenomic variables to the cardiovascular risks. The linear model we used to predict the ARU level included leukotriene B4, COX2 (rs20417) C/G and thromboxane A2 receptor (rs1131882) A/A genotypes with the addition of COX1 and ALOX15 promoter methylations as variables. The linear PRU prediction model included G/A and prostaglandin I receptor (rs4987262) G/A genotypes, COX2 and TXAS1 promoter methylation, as well as cytochrome P450 2C19*2 (rs4244285) A/A, G/A, and *3 (rs4986893) A/A genotypes as variables. The linear models for predicting ARU (r = 0.291, R2 = 0.033, p < 0.01) and PRU (r = 0.503, R2 = 0.210, p < 0.001) levels had improved prediction performance after adding the genomic and epigenomic variables to the cardiovascular risks.ConclusionsThis study demonstrates that different mediators, genomic and epigenomic characteristics of arachidonic acid metabolism and clopidogrel activation synergistically improved the prediction of the aspirin and clopidogrel resistance together with the cardiovascular risk factors.Trial registrationURL: https://www.clinicaltrials.gov; Unique identifier: NCT03823274.

Clopidogrel resistance and its relevance: Current concepts

ABSTRACT Clopidogrel is the most widely used P2Y12 receptor inhibitor (P2Y12i) as a part of dual antiplatelet therapy along with aspirin. Clopidogrel is a pro-drug and is metabolized to its active metabolite by the hepatic enzyme cytochrome P4502C19 (CYP2C19). This active metabolite is responsible for the antiplatelet action of clopidogrel. Recent studies have demonstrated that single nucleotide polymorphisms in the CYP2C19 gene, including CYP2C19*2,*3,*4, and *5 alleles, result in reduced production of the active metabolite of clopidogrel, and hence reduced inhibition of platelet aggregation. This in turn enhances the incidence of stent thrombosis and recurrent cardiovascular (CV) events. We report a case of coronary stent thrombosis due to clopidogrel resistance proven by CYP2C19 genotyping. We then review the literature on clopidogrel resistance and its impact on CV outcomes. Subsequently, we discuss the methods of diagnosis of resistance, evidence from clinical trials for tailoring clopidogrel therapy, the role of potent P2Y12 inhibitors, the current guidelines, and future directions.

A novel AllGlo probe-quantitative PCR method for detecting single nucleotide polymorphism in CYP2C19 to evaluate the antiplatelet activity of clopidogrel

CYP2C19 gene has multiple single nucleotide polymorphism (SNP), which is the major determinant for clopidogrel treatment responses. Therefore, CYP2C19 SNP detection is essential for predicting clopidogrel efficacy. Currently, there is still no quick and effective method for routine detection of common CYP2C19 SNPs in clinical laboratories, which is critically needed prior to clopidogrel treatment. AllGlo™ based quantitative PCR was used to develop a novel genotyping method for CYP2C19 SNP detection, termed CyPAllGlo. The performance of CyPAllGlo was compared with that of the commonly used fluorescence in situ hybridization (FISH) method, and the data was verified by DNA sequencing. CyPallGlo was used to identify CYP2C19 polymorphisms in 363 patients with coronary heart disease. The univariate analysis was used to access the antiplatelet efficacy of clopidogrel in patients. The associations between CYP2C19 polymorphisms and clopidogrel efficacy were analyzed. Using CyPAllGlo to detect CYP2C19*2 and CYP2C19*3 alleles was highly specific and fast. The detection limit was approximately 0.07 µg/µl and 0.7 µg/µl for CYP2C19*2 and CYP2C19*3, respectively. The consistency between FISH and CyPAllGlo were 98.07% for CYP2C19*2 and 99.17% for CYP2C19*3. DNA sequencing showed that the accuracy of CyPAllGlo was 100%. The analysis time for the whole CyPAllGlo procedure was approximately 60 min. Univariate analysis showed that the anticoagulation efficacy of clopidogrel was related to patient age, CYP2C19 genotype, metabolic phenotype, and LDL level. The logistic regression analysis showed that the genotype of CYP2C19 and metabolic phenotype was the two risk factors for clopidogrel antiplatelet ineffectiveness. This novel CyPAllGlo is a rapid and accurate method for detection of CYP2C19 SNP. The specificity and consistency of CyPAllGlo are comparable with that of widely used DNA sequencing. These findings provide valuable rapid method for predicting clopidogrel efficacy, which can be quickly translated to improve personalized precision medicine for coronary heart disease treatment.

Effect of Calcium Channel Blockers on Antiplatelet Activity of Clopidogrel in Patients Undergoing Percutaneous Coronary Intervention: Insights from the PTRG-DES Consortium

Aims: Calcium channel blockers (CCBs) are frequently co-administered with clopidogrel in cardiovascular disease. Although an inhibitory drug interaction exists between them, comprehensive large-scale studies for its validation are lacking. We investigated interactions between CCBs and clopidogrel using a large-scale national registry of patients who underwent percutaneous coronary intervention (PCI). Methods and Results: The Platelet function and genoType-Related long-term Prognosis-Platelet Function Test consortium investigates the association between platelet function test and long-term prognosis during dual antiplatelet therapy including clopidogrel in patients using drug-eluting stents. We compared the ex vivo platelet reactivity using the VerifyNow P2Y12 test and clinical outcomes between CCB users and non-users. Between 2003 and 2018, 11 714 patients were enrolled and categorized into two groups according to CCB usage. A composite endpoint encompassing all-cause mortality, myocardial infarction, stent thrombosis, or stroke was defined as a major adverse cardiac and cerebrovascular event (MACCE). During the 5-year follow-up period, no significant differences were observed in P2Y12 reaction units (215.8 ± 84.7 vs 218.4 ± 76.7, P = .156), MACCEs, major bleeding, or high platelet reactivity rates, even after adjusting for propensity score matching (PSM) and inverse probability of treatment weighting (IPTW). When limited to the high platelet reactivity cohort (≥252 PRU), the results remained consistent for MACCE [PSM-adjusted, HR: 0.923 (0.644-1.323), P-value .663; IPTW-adjusted, HR: 1.300 (0.822-2.056), P-value .262]. Conclusions: CCB and clopidogrel co-administration does not appear to significantly impact clopidogrel responsiveness or clinical outcomes. Despite these promising results, further investigation may be warranted. Clinical trial registration: Platelet Function and genoType-Related Long-term progGosis in DES-treated Patients: A Consortium From Multi-centered Registries [PTRG-DES]; NCT04734028

The impact of smoking status on clopidogrel responsiveness in patients with coronary artery disease who undergo percutaneous coronary intervention

Background: Previous studies have pointed out the disproportionate action of clopidogrel in inhibiting platelet aggregation due to smoking more than ten cigarettes per a day. This study was designed to examine whether smoking enhances clopidogrel responsiveness in patients who are clinically diagnosed with coronary artery disease (CAD), following percutaneous coronary intervention (PCI). Methods: A total of 324 IHD participants were enrolled in a case-control study. Platelet function test was performed to all participants two hours before PCI procedure to measure clopidogrel response. Participants were then categorized into a non-responder group (case group n = 111) and responder group (control group n = 213). Each group was subdivided into a smoker group and a non-smoker group. All participants received clopidogrel loading dose equivalent to 600 mg and scheduled for elective PCI. Participants’ age, gender, family history of chronic illnesses was recorded in this study. Results: Smoking participants displayed a significant higher level of hemoglobin as compared to the non-smoking participants among the responder and the non-responder study groups (14.6±0.55 vs. 13.12±0.38, P &lt; 0.029; 14.3±0.31 versus 12.96±0.39, P &lt; 0.033) but lower AUC level (17±9 vs. 45±6, P &lt; 0.005; 62±3 vs. 95±7, P &lt; 0.008). Additionally, smoking intensity enhanced clopidogrel responsiveness by odd’s ratio 0.4213 at 95% C.I. (0.259 - 0.684), P &lt; 0.0002. Conclusions: Current smokers had a good response to clopidogrel therapy which exerted a beneficial effect when undergoing PCI as compared to non-smokers. The marked difference in AUC between smokers and non-smokers could be related to the variance in hemoglobin level. The smokers’ paradox needs further justification to confirm this concept.

Atorvastatin Effect on Clopidogrel Efficacy in Patients with Peripheral Artery Disease

Both clopidogrel and atorvastatin metabolism are rooted in hepatic cytochrome p450 activation. There are published reports of atorvastatin interfering with clopidogrel metabolism by inhibiting the activation of clopidogrel. This in turn would decrease the therapeutic effect of clopidogrel potentially resulting in an increase in thrombotic events in patients who are taking both medications. The emergence of viscoelastic assays, such as Thromboelastography with platelet mapping (TEG-PM), has been utilized to identify prothrombotic states and may provide insight into a patient's microvascular coagulation profile. The aim of this prospective, observational study was to delineate the differences in platelet function between patients on clopidogrel alone versus those on clopidogrel and atorvastatin in patients that are undergoing peripheral revascularization. All patients undergoing revascularization between December 2020 and August 2022 were prospectively evaluated. Patients on clopidogrel and atorvastatin were compared to those on clopidogrel alone. Serial perioperative TEG-PM analysis was performed up to 6months postoperatively and the platelet function in terms of percent inhibition was evaluated in both groups. Statistical analysis was performed using unpaired t-test to identify differences in platelet function. Over the study period, a total of 182 patients were enrolled. Of this cohort 72 patients met study criteria. 87 samples from the 72 patients were analyzed. 31 (43.05%) patients were on clopidogrel alone and 41 (56.94%) were on clopidogrel and atorvastatin. Patients on clopidogrel alone showed significantly greater platelet inhibition compared to those on clopidogrel and atorvastatin [49.01% vs. 34.54%, P=0.03]. There was no statistical difference in platelet inhibition between groups in terms of aspirin use alone versus aspirin and atorvastatin. Patients on clopidogrel and atorvastatin showed significantly less platelet inhibition compared to those on clopidogrel alone, supporting the concept that atorvastatin may interfere with the therapeutic effect of clopidogrel. Patients taking atorvastatin may require an alternative antiplatelet therapy regimen that does not include clopidogrel to achieve adequate thromboprophylaxis.

The impact of smoking status on clopidogrel responsiveness in patients with coronary artery disease who undergo percutaneous coronary intervention

Background: Previous studies have pointed out the disproportionate action of clopidogrel in inhibiting platelet aggregation due to smoking more than ten cigarettes per a day. This study was designed to examine whether smoking enhances clopidogrel responsiveness in patients who are clinically diagnosed with coronary artery disease (CAD), following percutaneous coronary intervention (PCI). Methods: A total of 324 IHD participants were enrolled in a case-control study. Platelet function test was performed to all participants two hours before PCI procedure to measure clopidogrel response. Participants were then categorized into a non-responder group (case group n = 111) and responder group (control group n = 213). Each group was subdivided into a smoker group and a non-smoker group. All participants received clopidogrel loading dose equivalent to 600 mg and scheduled for elective PCI. Participants’ age, gender, family history of chronic illnesses was recorded in this study. Results: Smoking participants displayed a significant higher level of hemoglobin as compared to the non-smoking participants among the responder and the non-responder study groups (14.6±0.55 vs. 13.12±0.38, P &lt; 0.029; 14.3±0.31 versus 12.96±0.39, P &lt; 0.033) but lower AUC level (17±9 vs. 45±6, P &lt; 0.005; 62±3 vs. 95±7, P &lt; 0.008). Additionally, smoking intensity enhanced clopidogrel responsiveness by odd’s ratio 0.4213 at 95% C.I. (0.259 - 0.684), P &lt; 0.0002. Conclusions: Current smokers had a good response to clopidogrel therapy which exerted a beneficial effect when undergoing PCI as compared to non-smokers. The marked difference in AUC between smokers and non-smokers could be related to the variance in hemoglobin level. The smokers’ paradox needs further justification to confirm this concept.

Enhanced metabolic activation of and platelet response to clopidogrel in T cell-deficient mice through induction of Cyp2c and Cyp3a and inhibition of Ces1

BackgroundT cells and platelets reciprocally coordinate mutual functions through crosstalk or interaction. However, it is not known whether metabolic activation of and platelet response to clopidogrel could be changed if T cells were deficient or impaired in some cases and, if any, how it would work. ObjectivesThe objective of this study was to dissect the potential changes in platelet responses to and metabolic activation of clopidogrel in the case of T cell deficiency and to elucidate their mechanisms involved. MethodsBALB/c athymic nude mice or euthymic mice (controls) pretreated with cyclosporine A (CsA), thymosin α1 (Tα1), or their combination were used to investigate the changes in ADP-induced platelet activation and aggregation, systemic exposure of clopidogrel and its metabolites, and mRNA/protein expression and activity levels of clopidogrel-metabolizing enzymes in the liver, respectively. ResultsNude mice exhibited significantly enhanced antiplatelet effects of clopidogrel due to increased formation of clopidogrel active metabolite in the liver, where the enzyme activity levels of Cyp2c and Cyp3a were significantly elevated compared with control mice. Furthermore, the effects of CsA pretreatment on the metabolism of clopidogrel in euthymic mice were identical to those seen in athymic mice. As expected, concomitant use of Tα1 reversed all the observed effects of CsA on clopidogrel metabolism and relevant metabolic enzymes. ConclusionsT cell deficiency or suppression enhances the antiplatelet effects of clopidogrel due to the boosted metabolic activation of clopidogrel in the liver through a dramatic induction of Cyp2c and Cyp3a in mice, suggesting that the metabolism of substrate drugs of Cyp2c and Cyp3a may be enhanced by T cell impairment.

The Cytochrome P450 2C19 Polymorphism Associated with Major Adverse Cardiovascular Events Risk in Kazak Patients Undergoing Percutaneous Coronary Intervention and Receiving Clopidogrel.

Clopidogrel activity is influenced by cytochrome P450 (CYP450). CYP2C19 polymorphisms vary by ethnicity and region. The aim of the study is to assess the effect of genetic polymorphisms in CYP2C19*2 and *3 and clinical and demographic factors on major adverse cardiovascular events (MACE) in Kazak patients following percutaneous coronary intervention (PCI). 397 patients with PCI treated with clopidogrel and aspirin for at least 12 months were enrolled and outcomes within 1 year were recorded. Approximately 2 ml of peripheral venous blood samples were used for genotype detection. Multivariable logistic regression analyses were performed to identify factors associated with MACE. 95 patients (23.9%) suffered MACE during the period. Logistic regression analysis revealed CYP2C19*2 carriers (odds ratio [OR]: 2.431, 95% [confidence interval] CI: 1.136- 5.275, P = 0.027) and poor metabolizers (OR: 2.128, 95% CI: 0.899-4.82, P = 0.043) to be significantly associated with MACE. The CYP2C19*2 allele variants and poor metabolizers were found to be associated with MACE in a clopidogrel-treated Kazak population with acute coronary syndrome following PCI.

Prevalence of CYP2C9 and CYP2C19 variants and the impact on clopidogrel efficacy in patients having CYPC19*2 variant.

Human cytochrome p450 enzymes play an important role in the metabolism of various substances. The CYP2C subfamily consists of various important drug-metabolizing enzymes such as CYP2C9 and CYP2C19. The objectives of the study include the determination of the frequency of genetic variants (CYP2C9*2, CYP2C9*3, and CYP2C19*2) of selected enzymes using allele-specific polymerase chain reaction (ASPCR) and its comparison with Indian as well as global past frequencies. We also aimed to study the impact of genetic mutation on clopidogrel efficacy and compare the efficacies between patients with and without CYP2C19*2 genetic variant. In this study, the prevalence of variants CYP2C19*2, CYP2C9*2, and CYP2C9*3, the most popular variants of the respective enzymes, was determined using the ASPCR method. The correlation between the CYP2C19*2 variant and the antiplatelet activity of clopidogrel was studied using platelet aggregation assay (PAA). The determined frequencies of CYP2C19*2, CYP2C9*2, and CYP2C9*3 are 46%, 9%, and 12%. These frequencies are indicative of homozygous as well as heterozygous mutations. Reduced clopidogrel efficacy was observed in patients with a heterozygous mutation of CYP2C19*2 variant. The observed frequencies are not significantly different from that observed in earlier reported studies conducted across India and the world. Antiplatelet activity, as measured using the PAA method, was significantly lesser in patients having the CYP2C19*2 variant. The therapy failure in these patients can lead to serious cardiovascular consequences, and we propose determining the presence of the CYP2C19*2 variant before initiation of clopidogrel therapy.

Influence of CYP450 Enzymes and ABCB1 Polymorphisms on Clopidogrel Response in Moroccan Patients with Acute Coronary Syndromes.

Clopidogrel is an antiplatelet prodrug primarily prescribed to prevent or treat acute coronary syndrome (ACS) or acute ischemic stroke (IS), polymorphisms of genes encoding cytochrome P-450 (CYP) and P-glycoprotein transporter, could affect the efficiency of clopidogrel absorption and biotransformation, especially during the first critical hours following its administration. The present study was designed to investigate the potential association of clopidogrel responsiveness and 14 polymorphisms in the genes encoding the CYPs (CYP2C9, 2C19, 3A4, 3A5, 1A2, and 2B6), the ATP binding cassette subfamily B member 1 (ABCB1). Platelet aggregation activity was measured after 8h of 300mg clopidogrel administration for fifty-five ACS patients. There was no significant association between polymorphism of the studied CYPs and clopidogrel responsiveness (P>0.05). The frequency of the ABCB1 3435 T allele in clopidogrel non-responders was higher (78.9%) compared to responders (52.8%), but this difference was not significant (P=0.057). Demographic characteristics, comorbidities, concomitant treatments were not associated with clopidogrel response. There was no effect of the studied genetic variations and demographic factors on the platelet activity of clopidogrel in Moroccan ACS patients.

Reversal of Platelet Inhibition in Patients Receiving Ticagrelor.

Antiplatelet treatment is one of the pillars of contemporary therapy in acute coronary syndromes. It is based on dual antiplatelet therapy (DAPT) consisting of aspirin and a P2Y12 receptor inhibitor. Antiaggregatory treatment reduces ischemic events, but at cost of increased bleeding rates. As a result of irreversible inhibition of platelet P2Y12 receptors, the antiplatelet action of clopidogrel and prasugrel is prolonged for the lifespan of thrombocytes and lasts up to 7 days. The antiaggregatory effect of ticagrelor may persist up to 5 days despite its reversible nature of P2Y12 receptor inhibition. These pharmacodynamic properties may prove problematic in patients requiring immediate reversal of antiplatelet effects due to severe or life-threatening bleeding, or in presence of indications for an urgent surgery. The current review summarizes available knowledge on different strategies of restoring platelet function in patients treated with ticagrelor. Non-specific methods are discussed, including platelet transfusion, human albumin supplementation and hemadsorption. Finally, bentracimab, the first specific antidote for ticagrelor, and in fact against any antiplatelet agent, is described.

Correlation between oxidative stress and clopidogrel drug in Iraqi patients with coronary artery disease

Background: Coronary Artery Disease (CAD) is one of the largest causes of mortality worldwide. Clopidogrel, antiplatelet drug, has been widely used for management of CAD. The current study aimed to investigate the effect of clopidogrel on the oxidative stress in CAD patients. Methods: One hundred CAD patients, who were followed-up for 5 days after receiving clopidogrel, and 50 healthy volunteers were included in this study. Parameters include catalase (CAT), total antioxidant capacity (TAC), total oxidant capacity (TOC), total protein, albumin, and globulins were determined before and after treatment with clopidogrel. Results: CAT, TAC, and Tp were significantly decreased (P&lt;0.0001) in CAD patients compared to healthy control and the levels of these parameters were returned to increase after receiving clopidogrel. However, TOC level was markedly increased (P&lt;0.0001) in CAD patients and returned to decrease after treating with clopidogrel. Receiver operating characteristic curve showed that CAT gave a higher sensitivity (68-73%) and specificity (72%) as an indicator for monitoring of CAD progression. Conclusion: CAT activity and TAC were significantly increased as a response of receiving clopidogrel which is helpful to reduce the risk of CAD through scavenging of oxidants formation. These results also present CAT as a predictor variable of clopidogrel action.

Study on the Interaction between Deuterium Clopidogrel and Omeprazole

Introduction: Dual antiplatelet therapy with aspirin in combination with a P2Y₁₂ receptor antagonist is a cornerstone for treating patients with acute coronary syndrome and in percutaneous coronary intervention. However, as this combination of antiplatelet therapy increases the risk of bleeding, proton pump inhibitors (PPIs) are currently recommended to prevent gastrointestinal ulcers and bleeding. The cytochrome P450 (CYP450) isoenzyme system metabolizes both clopidogrel (CLP) and PPIs. Unfortunately, omeprazole (OM) reduce the antiplatelet activity of CLP and increases the probability of recurrence of cardiovascular events by competitively inhibiting the CYP450 isoenzyme CYP2C19. Methods: To address these abovementioned problems, we designed and synthesized deuterium CLP (D-CL) using selective deuterium technology. Our previous research results showed that D-CL had better pharmacokinetic and pharmacodynamic properties. Thus, the HPLC-MS/MS method, cocktail method, Born method, electro-stimulated thrombus generation, and thrombus elastography were used to detect the production of thiol active metabolites (AM), CYP450 enzyme activities, platelet aggregation, time and length of thrombus formation, and the maximum clot strength after combination therapy. We investigated the pharmacokinetics and pharmacodynamics properties of D-CL combined with OM. Results: As compared to CLP, D-CL was less affected when combined with OM, which was reflected in lower inhibitory effects of CYP450 enzyme activities, a greater area under the curve of AM, and better antiplatelet and antithrombotic effects. Conclusion: D-CL may reduce drug-drug interactions and address the clinical disadvantages of CLP.

Candidate Gene of NOS3, MMP3, AGT, and AGT1R and Pathway Analyses for Platelet Reactivity and Clinical Outcomes of Repeat Revascularization After First PCI in Chinese Patients.

Major disadvantages of the percutaneous coronary intervention (PCI) are the high occurrence of repeat revascularization due to restenosis and disease progression. The current study aimed to identify indicators that can predict the risk of repeat revascularization. A total of 143 patients who underwent PCI and had genetic test results were enrolled. We retrospectively reviewed their medical records after the first PCI. P2Y12 reaction unit (PRU) test results were obtained by VerifyNow; 4 candidate genes (NOS3, MMP3, AGT, and AGT1R) and 380 genes related to platelet activation-related processes and clopidogrel activity were selected for analysis. Repeat revascularization and in-stent restenosis (ISR) were used as clinical outcomes, and PRU and ADP aggregation rates were used as platelet function outcomes in analysis. After the first PCI, the incidence of repeat revascularization at 18, 30, and 42months was 14.1% (20/142), 17.5% (24/137), and 39.7% (31/78), respectively. In the candidate gene analysis, rs7830 (NOS3) was associated with both ADP aggregation rate and 18- and 30-month ISR, and rs 62,275,847 (AGTR1) was associated with both ADP aggregation rate and 30-month ISR. In the pathway, gene-set analysis, the linkage rs471683 and rs7785386 of GNAI1|GNAT3 were associated with PRU and ADP aggregation rate, 18-month and 30-month ISR, and repeat revascularization within 30months. Rs1715389 of GNAI1|GNAT3 was associated with both PRU and ADP aggregation rate, 18-month and 30-month ISR, and repeat revascularization within 30months. Rs7313458 of ITPR2 was associated with PRU and ADP aggregation rate, 18-month and 30-month ISR, and repeat revascularization within 18months. The genetic polymorphisms of rs7830 (NOS3), rs62275874 (AGTR1), linkage rs471683 and rs7785386 (GNAI1|GNAT3), rs1715389 (GNAI1|GNAT3), and rs7313458 (ITPR2) may lead to an increased risk of in-stent restenosis and revascularization after the first PCI in Chinese patients by affecting the efficacy of clopidogrel. The above six SNP may be used as potential genetic biomarkers for high risk of in-stent restenosis and revascularization after the first PCI in Chinese patients.

Preparation of injectable clopidogrel loaded submicron emulsion for enhancing physicochemical stability and anti-thrombotic efficacy

Due to the superior safety and therapeutic efficacy, clopidogrel (CLP) has been widely used to prevent postoperative thrombosis. However, limitations of delayed absorption and metabolic activation of clopidogrel after oral administration hinder its clinic use for acute thrombosis treatment in percutaneous coronary intervention (PCI). Although clopidogrel aqueous injection systems were designed and developed, chemical instability under physiological condition or vascular irritation remains to be solved. In this study, we aim to prepare an injectable clopidogrel loaded submicron emulsion to overcome the drawbacks of conventional clopidogrel aqueous formulation and improve the antiplatelet aggregation effects. Results showed that this delivery system exerted inspiring features including uniform particle size, higher drug loading capacity and sustained drug release behavior. It can dramatically upgrade the formulation stability and prevent the drug degradation under sterilization or higher pH environments. No remarkable droplet size increase or drug content decrease was observed during storage. Compared to CLP tablet, the peak drug concentration (Cmax) and area under the curve (AUC) of CLP emulsion increased by 12.01-fold and 4.69-fold, respectively. Most importantly, it exerted excellent in vivo anti-thrombotic effect on numerous designed animal models. Conclusively, submicron emulsion is a promising delivery system for improving clopidogrel stability and anti-thrombotic efficacy.

Is platelet responsiveness to clopidogrel attenuated in overweight or obese patients and why? A reverse translational study in mice

Overweight or obese patients exhibit poorer platelet responses to clopidogrel. However, the mechanisms behind this phenotype remain to be elucidated. Here, we sought to discover whether and why obesity could affect the metabolic activation of and/or platelet response to clopidogrel in obese patients and high-fat diet-induced obese mice. A post hoc stratified analysis of an observational clinical study was performed to investigate changes in residual platelet reactivity with increasing body weight in patients taking clopidogrel. Furthermore, high-fat diet-induced obese mice were used to reveal alterations in systemic exposure of clopidogrel thiol active metabolite H4, ADP-induced platelet activation and aggregation, the expression of genes involved in the metabolic activation of clopidogrel, count of circulating reticulated and mature platelets, and proliferation profiles of megakaryocytes in bone marrow. The relevant genes and potential signalling pathways were predicted and enriched according to the GEO datasets available from obese patients. Obese patients exhibited significantly attenuated antiplatelet effects of clopidogrel. In diet-induced obese mice, systemic exposure of clopidogrel active metabolite H4 was reduced but that of its hydrolytic metabolite was increased due to down-regulation of certain P450s but up-regulation of carboxylesterase-1 in the liver. Moreover, enhanced proliferation of megakaryocytes and elevated platelet count also contributed. Obesity attenuated metabolic activation of clopidogrel and increased counts of circulating reticulated and mature platelets, leading to impaired platelet responsiveness to the drug in mice, suggesting that clopidogrel dosage may need to be adjusted adequately in overweight or obese patients.

Effect of polymorphism of platelet receptors genes P2RY12, ITGB3 and CYP2C19 cytochrome metabolizer enzyme on the platelet activity and efficiency of clopidogrel in patients with stable stenocardia in the Grodno region

The aim of the study was to assess the distribution of polymorphic variants G681A of the CYP2C19 gene, H1/H2 of the P2RY12 gene, and T1565C of the ITGB3 gene and to study their effect on the platelet activity and clopidogrel efficacy in patients with stable stenocardia living in the Grodno region. The study included 92 patients with stable stenocardia, 89 of them underwent elective percutaneous coronary intervention (PCI), and 93 practically healthy people. The survey data (general clinical, aggregometry, general blood count and platelet indices, and polymerase chain reaction genotyping) were analyzed using the STATISTICA 10.0 software.A high prevalence of carriage of genotypes associated with possible variability in response to clopidogrel therapy was revealed both among patients with stable stenocardia and among practically healthy individuals in the Grodno region. The frequency of occurrence of studying genotypes among patients with stable stanocardia was 23.9 % for the CYP2C19 gene (polymorphic locus G681A), 40.2 % for the P2RY12 gene (polymorphic locus H1/H2), and 31.5 % for the gene ITGB3 (polymorphic locus T1565C). For the group of practically healthy individuals, the distribution of these genotypes was 18.3; 46.2; 37.6 %, respectively. Associations were revealed between the carriage of the 681A allele of the CYP2C19 gene and the H2 haplotype of the P2RY12 gene with high residual platelet reactivity during clopidogrel therapy in patients with stable stenocardia. An association was found between the carriage of the H2 haplotype of the H1/H2 polymorphism of the P2RY12 gene with high platelet MPV values and a higher frequency of large platelets (P-LCR) in patients with stable stenocardia.

Omeprazole-clopidogrel interaction and neurovascular complications after flow-diverter device placement

BackgroundOmeprazole is a common proton pump inhibitor that interferes with the hepatic activation of clopidogrel and potentially reduces its platelet-inhibitory effect. Omeprazole has been shown to increase P2Y12 levels and...