Pharmacokinetics Of Clopidogrel Research Articles

A pharmacokinetics interaction study of antiplatelet agents aspirin and clopidogrel combined with dl-3-n-butylphthalide in rats by liquid chromatography-tandem mass spectrometry.

A sensitive and specific high-performance liquid chromatography-tandem mass spectrometry method has been developed to determine the pharmacokinetic interactions of the antiplatelet agents aspirin and clopidogrel combined with dl-3-n-butylphthalide. For the determination of aspirin metabolite salicylic acid, clopidogrel inactive metabolite SR26334 and NBP prototype drug in rat plasma, plasma samples were prepared by precipitation of proteins using methanol containing 0.1% formic acid, followed by centrifugation. Chromatography was performed on a C18 column, eluting with a gradient of acetonitrile (with 0.1% formic acid)-water (with 0.1% formic acid). The detection adopted electrospray ion source and positive ion multiple reaction monitoring modes. The linear detection response range of salicylic acid is 80-80,000 ng/ml, and the linear detection response range of SR26334 and dl-3-n-butylphthalide is 10-10,000 ng/ml. Our study revealed that dl-3-n-butylphthalide affected the pharmacokinetics of aspirin and clopidogrel when administered to rats.

Effect of chronic unpredicted mild stress-induced depression on clopidogrel pharmacokinetics in rats.

BackgroundClopidogrel is widely used to prevent and treat cardiovascular atherosclerosis and thrombosis. However, disturbance in the expression and activity of liver cytochrome metabolic enzymes significantly changes clopidogrel efficacy. Therefore, the effect of chronic unpredictable mild stress (CUMS)-induced depression on the expression of liver cytochrome metabolic enzymes and clopidogrel pharmacokinetics in rats were explored.MethodsNine different CUMSs were selected to establish a rat model of depression. Open field experiment and sucrose preference test were applied to explore the depressive behaviors. The concentration of serotonin in the cortex of depressed rats was determined using enzyme linked immunosorbent assay (ELISA). All rats were given 10 mg/kg clopidogrel orally after 12 weeks, and blood samples were collected at different time points. The clopidogrel concentration and CYP2C19/ CYP2C9 activity in rat liver microsomes were assayed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The rat liver drug enzymes expression was determined by Real-Time Quantitative Reverse Transcription PCR (RT-qPCR).ResultsOpen field experiment and sucrose preference test indicated the successful construction of the CUMS-induced depression model. The concentration of serotonin in the cortex of depressed rats decreased by 42.56% (∗∗p < 0.01). The area under the curve of clopidogrel pharmacokinetics decreased by 33.13% (∗p < 0.05) in the depression rats, while distribution volume and clearance increased significantly (∗∗p < 0.01). The half-time and distribution volume did not significantly differ. The CYP2C19 and CYP2C9 activity of liver microsomes in the CUMS-induced depression group were significantly higher than that in the control group (∗∗p < 0.01). CYP2C11 and CYP1A2 mRNA expression up-regulated approximately 1.3 - fold in the depressed rat livers compared with that in the control, whereas that of CYP2C13 was down-regulated by 27.43% (∗∗p < 0.01). CYP3A1 and CYP2C12 expression were slightly up-regulated, and that of CES1 did not change.ConclusionsThese results indicated that CUMS-induced depression altered clopidogrel pharmacokinetics, and the change in CYP450 activity and expression in depressed rat livers might contribute to the disturbance of clopidogrel pharmacokinetics.

Interaction study of salvianolic acids for injection on pharmacokinetics of clopidogrel in rats using LC-MS/MS.

Salvianolic acids for injection (SAI) is developed from traditional Chinese medicine and approved for the treatment of cardiovascular and cerebrovascular diseases. Clopidogrel is an inhibitor of platelet aggregation, which is often prescribed for patients in combination with SAI. This present study aimed to assess the effects of SAI on the pharmacogenomics, pharmacokinetics, and pharmacodynamics of clopidogrel, thereby ensuring the safety and efficacy of coadministration. In vitro cytochrome P450 isoenzyme assays were performed in human liver microsomes using LC-MS/MS method to assess the metabolites of CYPs substrates. The effects of SAI on the pharmacokinetic and pharmacodynamic behaviors of clopidogrel were investigated in rats. The main pharmacokinetic parameters were analyzed using LC-MS/MS. Prothrombin time, activated partial thromboplastin time, bleeding time, and inhibition of platelet aggregation were measured to evaluate the effects of pharmacodynamics. Our study revealed that the clinical dose of SAI has no significant inhibitory effect on clopidogrel-related liver microsome metabolic CYP450 isoenzymes. Moreover, SAI did not affect the pharmacokinetics of clopidogrel when rats were administered both single and multiple doses. In pharmacodynamic study, SAI has no effect on platelet aggregation rate, prothrombin time, and activated partial thromboplastin time of clopidogrel but could significantly prevent the risk of bleeding caused by clopidogrel.

A physiologically based pharmacokinetic model of clopidogrel in populations of European and Japanese ancestry: An evaluation of CYP2C19 activity.

ABSTRACTTreatment response to clopidogrel is associated with CYP2C19 activity through the formation of the active H4 metabolite. The aims of this study were to develop a physiologically based pharmacokinetic (PBPK) model of clopidogrel and its metabolites for populations of European ancestry, to predict the pharmacokinetics in the Japanese population by CYP2C19 phenotype, and to investigate the effect of clinical and demographic factors. A PBPK model was developed and verified to describe the two metabolic pathways of clopidogrel (H4 metabolite, acyl glucuronide metabolite) for a population of European ancestry using plasma data from published studies. Subsequently, model predictions in the Japanese population were evaluated. The effects of CYP2C19 activity, fluvoxamine coadministration (CYP2C19 inhibitor), and population‐specific factors (age, sex, BMI, body weight, cancer, hepatic, and renal dysfunction) on the pharmacokinetics of clopidogrel and its metabolites were then characterized. The predicted/observed ratios for clopidogrel and metabolite exposure parameters were acceptable (twofold acceptance criteria). For all CYP2C19 phenotypes, steady‐state AUC0‐τ of the H4 metabolite was lower for the Japanese (e.g., EM, 7.69 [6.26–9.45] ng·h/ml; geometric mean [95% CI]) than European (EM, 24.8 [20.4–30.1] ng·h/ml, p < .001) population. In addition to CYP2C19‐poor metabolizer phenotype, fluvoxamine coadministration, hepatic, and renal dysfunction were found to reduce H4 metabolite but not acyl glucuronide metabolite concentrations. This is the first PBPK model describing the two major metabolic pathways of clopidogrel, which can be applied to populations of European and Japanese ancestry by CYP2C19 phenotype. The differences between the two populations appear to be determined primarily by the effect of varying CYP2C19 liver activity.

Physiologically-Based Pharmacokinetic-Pharmacodynamics Model Characterizing CYP2C19 Polymorphisms to Predict Clopidogrel Pharmacokinetics and Its Anti-Platelet Aggregation Effect Following Oral Administration to Coronary Artery Disease Patients With or Without Diabetes

Background and Objective: Clopidogrel (CLOP) is commonly used in coronary artery disease (CAD) patients with or without diabetes (DM), but these patients often suffer CLOP resistance, especially those with diabetes. This study was aimed to develop a physiologically-based pharmacokinetic-pharmacodynamic (PBPK-PD) model to describe the pharmacokinetics and pharmacodynamics of clopidogrel active metabolite (CLOP-AM) in CAD patients with or without DM. Methods: The PBPK-PD model was first established and validated in healthy subjects and then in CAD patients with or without DM. The influences of CYP2C19, CYP2C9, CYP3A4, carboxylesterase 1 (CES1), gastrointestinal transit rates (K t,i) and platelets response to CLOP-AM (k irre) on predicted pharmacokinetics and pharmacodynamics were investigated, followed with their individual and integrated effects on CLOP-AM pharmacokinetics due to changes in DM status. Results: Most predictions fell within 0.5–2.0 folds of observations, indicating successful predictions. Sensitivity analysis showed that contributions of interested factors to pharmacodynamics were CES1> k irre> K t,i> CYP2C19 > CYP3A4> CYP2C9. Mimicked analysis showed that the decreased exposure of CLOP-AM by DM was mainly attributed to increased CES1 activity, followed by decreased CYP2C19 activity. Conclusion: The pharmacokinetics and pharmacodynamics of CLOP-AM were successfully predicted using the developed PBPK-PD model. Clopidogrel resistance by DM was the integrated effects of altered K t,i, CYP2C19, CYP3A4, CES1 and k irre.

Effect of Smoking Cessation on the Pharmacokinetics and Pharmacodynamics of Clopidogrel after PCI: The Smoking Cessation Paradox Study.

Cigarette smoking is associated with enhanced clopidogrel effect and platelet inhibition. However, the effect of smoking cessation on clopidogrel pharmacokinetics (PK) and pharmacodynamics (PD) is unknown. We aimed to determine the effect of smoking cessation, confirmed by cotinine measurement, on clopidogrel PK and PD after percutaneous coronary intervention (PCI). Following successful PCI, patients treated with 75 mg/day clopidogrel who reported smoking ≥10 cigarettes/day with NicAlert urine cotinine level 6 were enrolled. Clopidogrel and its metabolite concentrations, VerifyNow P2Y12 reaction units (PRUs), and NicAlert levels were measured in the study group before and at 30 days after smoking cessation and in a control group. CYP1A2 and CYP2C19 genotypes were determined. At 30-day visit (n = 87), 45 patients continued smoking, whereas 42 patients stopped smoking. Baseline PRUs were similar between groups. At 30 days, the smoking cessation group had higher PRUs (150.5 ± 68.6 vs. 118.4 ± 65.9, p = 0.03), greater absolute PRU change (27.7 ± 39.8 vs. -12.9 ± 55.4, p = 0.0002), greater change of PRUs adjusted for baseline platelet reactivity (38.6 ± 10.0, p < 0.01), greater risk of high platelet reactivity (HPR) (odds ratio: 10.14 [1.52-67.5], p = 0.017), and a trend towards decreased H3 clopidogrel metabolite levels (-3.41 ng/mL [-11.00 to 0.54 ng/mL], p = 0.072). CYP2C19 LoF carriers who stopped smoking had the highest PRUs, whereas those with the wild type who continued smoking had the lowest PRUs (p < 0.008). Smoking cessation in clopidogrel-treated patients after PCI is associated with increased platelet reactivity and greater risk of HPR. Alternative P2Y12 inhibitors may be considered in selected patients who stop smoking after PCI.

Impact of genetic variants of selected cytochrome P450 isoenzymes on pharmacokinetics and pharmacodynamics of clopidogrel in patients co-treated with atorvastatin or rosuvastatin.

Impaired antiplatelet effect of clopidogrel (CLP) can result from drug-drug interactions and genetic polymorphisms of drug-metabolizing enzymes. The aim of the study was to evaluate the effect of genetic polymorphisms of ABCB1 and the selected cytochrome P450 isoenzymes on the pharmacodynamics and pharmacokinetics of CLP and its metabolites in patients co-treated with atorvastatin or rosuvastatin. The study involved 50 patients after coronary angiography/angioplasty treated with CLP and atorvastatin (n= 25) or rosuvastatin (n= 25) for at least 6months. Plasma concentrations of CLP, diastereoisomers of thiol metabolite (inactive H3 and active H4), and inactive CLP carboxylic acid metabolite were measured by UPLC-MS/MS method. Identification of the CYP2C19*2, CYP2C19*17, CYP3A4*1G, CYP1A2*1F, and ABCB1 C3435T genetic polymorphisms was performed by PCR-RFLP, while platelet reactivity units (PRU) were tested using the VerifyNow P2Y12 assay. There were significant differences in the pharmacokinetic parameters of the H4 active metabolite of CLP in the atorvastatin and rosuvastatin group divided according to their CYP2C19 genotype. There were no significant associations between CYP3A4, CYP1A2, and ABCB1 genotypes and pharmacokinetic parameters in either statin groups. In the multivariate analysis, CYP2C19*2 genotype and non-genetic factors including BMI, age, and diabetes significantly affected platelet reactivity in the studied groups of patients (P< 0.01). In the atorvastatin group, CYP2C19*2, CYP3A4*1G, and ABCB1 C3435T TT genotypes were independent determinants of PRU values (P< 0.01). The CYP2C19*2 allele is the primary determinant of the exposition to the H4 active metabolite of clopidogrel and platelet reactivity in patients co-treated with atorvastatin or rosuvastatin.

Kajian Sistematik: Efek Gen Multi Drug Resistance-1 pada Farmakokinetik Klopidogrel

Multi Drug Resistance-1 (MDR-1) gene polymorphisms encoding for P-glycoprotein can affect clopidogrel intestinal absorption. This systematic review aim to identify the impact of MDR-1 gene 3435 variants on clopidogrel pharmacokinetics. Literature review were retrieved from MEDLINE, Science Direct, Scopus, Clinical Key, ProQuest and Google Scholar databases. The articles are critically reviewed and analyzed to answer this systematic review’s aim. The result showed that, in patients with cardiovascular disease, the peak plasma concentration (Cmax) and the total area under the plasma concentration–time curve (AUC) of clopidogrel and its active metabolites were lower in 3435TT compared to 3435CC. Nevertheless, the variants of MDR-1 gene were not significantly correlated to the plasma concentration in healthy subjects. Clopidogrel pharmacokinetic profile varied widely between MDR-1 3435 variants and subjects.

Clopidogrel Pharmacokinetics in Malaysian Population Groups: The Impact of Inter-Ethnic Variability.

Malaysia is a multi-ethnic society whereby the impact of pharmacogenetic differences between ethnic groups may contribute significantly to variability in clinical therapy. One of the leading causes of mortality in Malaysia is cardiovascular disease (CVD), which accounts for up to 26% of all hospital deaths annually. Clopidogrel is used as an adjunct treatment in the secondary prevention of cardiovascular events. CYP2C19 plays an integral part in the metabolism of clopidogrel to the active metabolite clopi-H4. However, CYP2C19 genetic polymorphism, prominent in Malaysians, could influence target clopi-H4 plasma concentrations for clinical efficacy. This study addresses how inter-ethnicity variability within the Malaysian population impacts the attainment of clopi-H4 target plasma concentration under different CYP2C19 polymorphisms through pharmacokinetic (PK) modelling. We illustrated a statistically significant difference (P < 0.001) in the clopi-H4 Cmax between the extensive metabolisers (EM) and poor metabolisers (PM) phenotypes with either Malay or Malaysian Chinese population groups. Furthermore, the number of PM individuals with peak clopi-H4 concentrations below the minimum therapeutic level was partially recovered using a high-dose strategy (600 mg loading dose followed by a 150 mg maintenance dose), which resulted in an approximate 50% increase in subjects attaining the minimum clopi-H4 plasma concentration for a therapeutic effect.

The ABCB1, CYP2C19, CYP3A5 and CYP4F2 genetic polymorphisms and platelet reactivity in the early phases of acute coronary syndromes.

Abstract Background The aim was to study seven polymorphic markers of genes encoding proteins involved in the absorption, metabolism and pharmacokinetics of clopidogrel among patients with an acute coronary syndrome (ACS), who have undergone percutaneous coronary intervention (PCI). Methods Eighty-one ACS and PCI patients older than 18 years and treated with dual antiplatelet therapy were enrolled in the study. Platelet function testing and ABCB1, CYP2C19, CYP3A5 and CYP4F2 genotyping were performed. The predictive role of categorical variables, such as genotypes (carriers and non-carriers of polymorphism), on platelet reactivity (platelet reactivity units [PRU] platelet inhibition [PI]) was assessed by logistic regression (for categorical outcomes) and linear regression (for continuous outcomes) analysis. A p-value&lt;0.05 was considered significant. The allele frequencies were estimated by gene counting, and Hardy-Weinberg equilibrium was tested using the chi-square test. Results Regarding clopidogrel response, 62 patients (76.5%) were clopidogrel responders and 19 were non-responders (23.5%). Mean PRU value and the percentage of platelet inhibition were 170.0±50.9 PRU and 28.6±19.9%, respectively. The effects of the CYP2C19*2 polymorphisms on PRU (166.0±50.8 vs. 190.7±48.2, p&lt;0.038) and PI (30.6±20.0 vs. 18.1±16.3, p&lt;0.013) were observed, and the rates of high platelet reactivity (HPR) were lower in CYP2C19*1/*1 than those in CYP2C19*1/*2+CYP2C19*2/*2 (16.2% vs. 53.8% p&lt;0.0067). In comparison, no significant difference in PRU value and PI was observed at &lt;5 days between the rest of polymorphisms (p&gt;0.05). Based on the logistic regression analysis, CYP2C19*2 (OR: 4.365, CI: 1.25–17.67, p=0.022) was an independent predictor of HPR at &lt;5 days, as was the stent diameter (OR: 0.219, CI: 0.002–0.229, p=0.049). The remaining polymorphisms had no influence. Conclusions The reactivity of the on-clopidogrel platelet in the early phase of ACS is influenced primarily by the CYP2C19 polymorphisms. We believe that the findings of the present study could supply additional evidence regarding the clinical appropriateness of the CYP2C19 genetic testing for designing suitable antiplatelet therapy in the early phase of ACS.

Clinical Relevant Polymorphisms Affecting Clopidogrel Pharmacokinetics and Pharmacodynamics: Insights from the Puerto Rico Newborn Screening Program.

Background: Variations in several clopidogrel-pharmacogenes have been linked to clopidogrel response variability and clinical outcomes. We aimed to determine the frequency distribution of major polymorphisms on CYP2C19, PON1, ABCB1 and P2RY12 pharmacogenes in Puerto Ricans. Methods: This was a cross-sectional, population-based study of 200 unrelated “Guthrie” cards specimens from newborns registered in the Puerto Rican newborn screening program (PRNSP) between 2004 and 2014. Taqman® SNP assay techniques were used for genotyping. Results: Minor allele frequencies (MAF) were 46% for PON1 (rs662), 41% for ABCB1 (rs1045642), 14% for CYP2C19*17, 13% for CYP2C19*2, 12% for P2RY12-H2 and 0.3% for CYP2C19*4. No carriers of the CYP2C19*3 variants were detected. All alleles and genotype proportions were found to be in Hardy–Weinberg equilibrium (HWE). Overall, there were no significant differences between MAFs of these variants in Puerto Ricans and the general population (n = 453) of the 1000 Genome project, except when comparisons to each individual parental group were performed (i.e., Africans, Europeans and East-Asians; p < 0.05). As expected, the prevalence of these markers in Puerto Ricans most resembled those in the 181 subjects from reference populations of the Americas. Conclusions: These prevalence data provide a necessary groundwork for future clinical studies of clopidogrel pharmacogenetics in Caribbean Hispanics.

Effects of Danshen capsules on the pharmacokinetics and pharmacodynamics of clopidogrel in healthy volunteers

Nowadays, the Herb-drug combination is becoming increasingly popular in China. However, the possible interaction induced by their combination was examined rarely. The aim of this study was to investigate the effect of multi-dose administration of Danshen capsules on clopidogrel pharmacokinetics and pharmacodynamics in healthy volunteers. A sequential, open-label, and two-period pharmacokinetic drug interaction study was designed to compare clopidogrel pharmacokinetic parameters before and after 7 days of administration of Danshen capsules in twenty healthy male volunteers. Co-administration of multiple doses of Danshen capsules caused increases in apparent oral clearance of clopidogrel and its metabolite by 96.5% and 73.7% and apparent volume of distribution by 94.2% and 75.1%, corresponding declines in Cmax by 41.7% and 32.9%, AUC0-t by 50.3% and 41.8%, and AUC0-∞ by 49.3% and 41.5% in human volunteers, respectively. Corresponding pharmacokinetic findings, co-administration of Danshen capsules with clopidogrel decreased the antiplatelet activity compared with individual agents. The results suggested that multiple dose administration of Danshen capsules could induce cytochrome P450 (CYP) isoenzymes, thereby increasing the clearance of clopidogrel. Therefore, caution should be taken when Danshen products containing lipophilic components are used in combination with therapeutic drugs metabolized by CYP3A4.

Cigarette smoking reduces platelet reactivity independently of clopidogrel treatment in patients with non-ST elevation acute coronary syndromes

Smokers receiving clopidogrel show a lower residual platelet reactivity than non-smokers, a phenomenon generally ascribed to smoking-induced increased production of clopidogrel active metabolite, but also associated with the high hemoglobin levels of smokers, which decreases platelet reactivity in tests that measure platelet function in whole blood. We evaluated the impact of cigarette smoking and of hemoglobin levels on platelet reactivity index (PRI) measured by the vasodilator-stimulated phosphoprotein phosphorylation (VASP-P) assay in whole blood samples from patients with non-ST elevation acute coronary syndrome (NSTE-ACS) undergoing percutaneous coronary interventions, both before and after clopidogrel administration.PRI was measured in 718 clopidogrel-naïve NSTE-ACS patients, both before and 1 month after treatment with clopidogrel (75 mg daily). Smokers (n = 347, 48%) had significantly lower mean PRI levels at both baseline (57.7 ± 24.1 vs. 64.8 ± 19.8, p < 0.001) and 1 month (43.4 ± 20.3% vs. 46.8 ± 18.0%, p = 0.017) than non-smokers. After adjusting for potential confounders (age, sex, diabetes, chronic kidney disease, Syntax score>15), the β coefficient of smoke on PRI was −8.51 [−11.90 to −5.11, p < 0.001] at baseline and −3.41 [−6.30 to −0.51, p = 0.02] after 1 month. Hemoglobin was higher in smokers (13.8 ± 1.5 g/dL) than non-smokers (13.1 ± 1.7 g/dL, p < 0.001), but was not significantly correlated with PRI both at baseline (Rho = 0.02, p = 0.60) and at 1 month (Rho = 0.01, p = 0.80).Our analysis confirms that clopidogrel-treated smokers have lower platelet reactivity, measured by the VASP-P assay, compared to clopidogrel-treated non-smokers. However, smokers had lower platelet reactivity already before receiving clopidogrel treatment, suggesting that smoke affects platelet reactivity independently of its potential effect on the pharmacokinetics of clopidogrel. Our data also indicate that such an effect is not mediated by increased hemoglobin levels.

Effects of Genetic Variants on Carboxylesterase 1 Gene Expression, and Clopidogrel Pharmacokinetics and Antiplatelet Effects.

Several single nucleotide variations (SNVs) affect carboxylesterase 1 (CES1) activity, but the effects of genetic variants on CES1 gene expression have not been systematically investigated. Therefore, our aim was to investigate effects of genetic variants on CES1 gene expression in two independent whole blood sample cohorts of 192 (discovery) and 88 (replication) healthy volunteers and in a liver sample cohort of 177 patients. Furthermore, we investigated possible effects of the found variants on clopidogrel pharmacokinetics (n=106) and pharmacodynamics (n=46) in healthy volunteers, who had ingested a single 300mg or 600mg dose of clopidogrel. Using massively parallel sequencing, we discovered two CES1 SNVs, rs12443580 and rs8192935, to be strongly and independently associated with a 39% (p=4.0×10-13 ) and 31% (p=2.5×10-8 ) reduction in CES1 whole blood expression per copy of the minor allele. These findings were replicated in the replication cohort. However, these SNVs did not affect CES1 liver expression, or clopidogrel pharmacokinetics or pharmacodynamics. Conversely, the CES1 c.428G>A missense SNV (rs71647871) impaired the hydrolysis of clopidogrel, increased exposure to clopidogrel active metabolite and enhanced its antiplatelet effects. In conclusion, the rs12443580 and rs8192935 variants reduce CES1 expression in whole blood but not in the liver. These tissue-specific effects may result in substrate-dependent effects of the two SNVs on CES1-mediated drug metabolism.

Obesity and Inflammation and Altered Clopidogrel Pharmacokinetics and Pharmacodynamics.

Clopidogrel is a key antiplatelet drug that has substantial interpatient variability in pharmacodynamic response. Patients with lesser degrees of platelet inhibition in response to clopidogrel appear to be at increased risk of cardiovascular events. Obesity is an independent risk factor for cardiovascular morbidity and mortality due to atherothrombotic events and represents a group of patients who are in need of optimized antithrombotic therapy. Central to the obesity-related risk of atherothrombosis is a pro-thrombotic state characterized by increased levels of coagulation factors, impaired fibrinolysis and platelet hyper-reactivity, which results from the interaction among the features clustering in obesity: insulin resistance, inflammation, oxidative stress, and endothelial dysfunction. A number of reports have demonstrated that obesity is a risk factor for a reduced clopidogrel pharmacodynamic response. The inflammatory state associated with obesity, particularly a metabolic endotoxemia, may set in motion, a number of mechanisms that increase platelet reactivity, suppress cytochrome P450 enzyme activity, and increase platelet turnover, all contributing to a poor clopidogrel response. Comprehensive understanding of the mechanisms underlying obesity-related high onclopidogrel platelet reactivity will help in the optimization of antithrombotic therapy in this patient population.

Clopidogrel Carboxylic Acid Glucuronidation is Mediated Mainly by UGT2B7, UGT2B4, and UGT2B17: Implications for Pharmacogenetics and Drug-Drug Interactions .

The antiplatelet drug clopidogrel is metabolized to an acyl-β-d-glucuronide, which causes time-dependent inactivation of CYP2C8. Our aim was to characterize the UDP-glucuronosyltransferase (UGT) enzymes that are responsible for the formation of clopidogrel acyl-β-d-glucuronide. Kinetic analyses and targeted inhibition experiments were performed using pooled human liver and intestine microsomes (HLMs and HIMs, respectively) and selected human recombinant UGTs based on preliminary screening. The effects of relevant UGT polymorphisms on the pharmacokinetics of clopidogrel were evaluated in 106 healthy volunteers. UGT2B7 and UGT2B17 exhibited the greatest level of clopidogrel carboxylic acid glucuronidation activities, with a CLint,u of 2.42 and 2.82 µl⋅min-1⋅mg-1, respectively. Of other enzymes displaying activity (UGT1A3, UGT1A9, UGT1A10-H, and UGT2B4), UGT2B4 (CLint,u 0.51 µl⋅min-1⋅mg-1) was estimated to contribute significantly to the hepatic clearance. Nonselective UGT2B inhibitors strongly inhibited clopidogrel acyl-β-d-glucuronide formation in HLMs and HIMs. The UGT2B17 inhibitor imatinib and the UGT2B7 and UGT1A9 inhibitor mefenamic acid inhibited clopidogrel carboxylic acid glucuronidation in HIMs and HLMs, respectively. Incubation of clopidogrel carboxylic acid in HLMs with UDPGA and NADPH resulted in strong inhibition of CYP2C8 activity. In healthy volunteers, the UGT2B17*2 deletion allele was associated with a 10% decrease per copy in the plasma clopidogrel acyl-β-d-glucuronide to clopidogrel carboxylic acid area under the plasma concentration-time curve from 0 to 4 hours (AUC0-4) ratio (P < 0.05). To conclude, clopidogrel carboxylic acid is metabolized mainly by UGT2B7 and UGT2B4 in the liver and by UGT2B17 in the small intestinal wall. The formation of clopidogrel acyl-β-d-glucuronide is impaired in carriers of the UGT2B17 deletion. These findings may have implications regarding the intracellular mechanisms leading to CYP2C8 inactivation by clopidogrel.

Development and validation of a sensitive and rapid UHPLC–MS/MS method for the simultaneous quantification of the common active and inactive metabolites of vicagrel and clopidogrel in human plasma

Vicagrel, an analog of clopidogrel, is a novel thienopyridine P2Y12 antagonist in clinical development in China for the treatment of acute coronary syndromes. Vicagrel and clopidogrel are prodrugs requiring metabolic activation to produce a pharmacologically active thiol metabolite (H4) in vivo. The formation of H4 from vicagrel in humans is promising more efficient and consistent than that from clopidogrel. After oral dosing of vicagrel or clopidogrel to humans, the active thiol metabolite H4 and two inactive metabolites closely related to H4 formation (the thiol metabolite H3 and the S-methylated metabolite SM3) were observed in plasma; SM3 was the most abundant drug-related component of vicagrel in circulation. In this study, a sensitive, rapid, and reliable UHPLC–MS/MS method was developed for the simultaneous determination of derivatized H3 (MP-H3), derivatized H4 (MP-H4), and SM3 in human plasma to investigate the pharmacokinetics of vicagrel in healthy subjects compared with clopidogrel. After extracted from 50μL of plasma by simple protein precipitation, the analytes and stable isotope-labeled internal standards were separated on an Acquity UPLC BEH C18 column (100mm×2.1mm, 1.7μm). The mobile phase was acetonitrile–water–formic acid (45:55:0.0275, v/v/v) delivered at a flow rate of 0.45mL/min under isocratic elution. The total chromatographic run time was 6min. MP-H3, MP-H4, and SM3 were separated from their corresponding isomers under the chromatographic conditions. Mass spectrometric detection was conducted in multiple reaction monitoring mode on an AB Sciex Qtrap 5500 System using a positive electrospray ionization interface. The calibration curves were linear in the following ranges: 0.100–200ng/mL for MP-H3 and MP-H4 and 1.00–1000ng/mL for SM3. The intra- and inter-day accuracy and precision for each analyte at all concentrations were within acceptable limits (±15%). The validated method was successfully applied to compare the pharmacokinetics of vicagrel and clopidogrel after a single oral administration to healthy subjects in the first-in-human study of vicagrel.

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

PurposeA 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).MethodsThe 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).ResultsIt 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).ConclusionsDeveloped 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.

A pharmacokinetic model of drug-drug interaction between clopidogrel and omeprazole at CYP2C19 in humans.

Clopidogrel is a thienopryridine antiplatelet agent commonly used in the management of cardiovascular diseases. Clopidogrel is metabolized by hepatic CYP2C19 and CYP2B6, therefore, co-administration of clopidogrel and CYP2C19 inhibitors can alter pharmacokinetics of clopidogrel. Omeprazole is a proton pump inhibitor used for decreasing gastric acid production. Omeprazole is known to be a potent inhibitor of CYP2C19. Thus when the drugs are simultaneously administered, clopidogrel plasma concentration levels can be increased. However, plasma levels of the active metabolite of clopidogrel can be significantly decreased, thereby, its antiplatelet activity is reduced. We aimed to develop a mathematical model describing a drug-drug interaction between clopidogrel and omeprazole in humans. Searching for pharmacokinetic interaction studies between clopidogrel and omeprazole in humans was performed in PubMed. Six studies were selected into our modeling purposes to develop 3 mathematical models (i.e. 4 studies for clopidogrel alone, 1 study for omeprazole alone and 1 study for clopidogrel-omeprazole interaction). Subsequently, concentration-time course data from the selected studies were extracted. Computer codes and simulations were performed using the Advanced Continuous Simulating Language Extreme (ACSLX) program. We successfully developed 3 mathematical models which are able to describe all of the datasets. Our clopidogrel-omeprazole pharmacokinetic interaction model with a description of competitive inhibition at CYP2C19 could successfully describe concentration-time courses from the selected datasets. Our interaction model may be useful in predicting plasma levels of clopidogrel and its active metabolite.

PHARMACOKINETIC DRUG INTERACTION BETWEEN CLOPIDOGREL AND ESOMEPRAZOLE IN ADULT HEALTHY MALE VOLUNTEERS

Objective: Proton pump inhibitors (PPIs) are known to impair cytochrome P2C19 mediated activation of clopidogrel, the antiplatelet agent used for cardiovascular risk prevention. Esomeprazole is an optical isomer of omeprazole with better efficacy and tolerability than conventional PPIs. Esomeprazole is often co-administered with clopidogrel considering the risk of associated gastrointestinal bleeding. This study was designed to determine the effect of esomeprazole on the mean pharmacokinetic profile clopidogrel.Methods: A total of 14 adult healthy male participants who volunteered participation were enrolled, randomized equally into two cross-over sequences, dosed with clopidogrel and clopidogrel + esomeprazole in respective periods. Blood samples were collected through antecubital or forearm vein indwelling catheter. Concentration of clopidogrel parent prodrug in isolated plasma was determined using validated sensitive liquid chromatography – mass spectrometry. Pharmacokinetic modeling was carried out using PKSOLVER add-in for Microsoft Excel.Results: The pharmacokinetic profile of clopidogrel was non-significantly altered by esomeprazole. Statistically significant difference in peak plasma concentration, apparent volume of distribution, and clearance of clopidogrel was observed only during period II in participants co-dosed with esomeprazole (p=0.0483, 0.0011, and 0.0015, respectively). All other primary and secondary pharmacokinetic parameters displayed minor alterations during either period (p&gt;0.05).Conclusion: The non-significant alteration of clopidogrel pharmacokinetics by esomeprazole can be potentiated by underlying predisposing factors such as the presence of CYP2C19 allelic variants and increasing the risk of cardiovascular events. Hence, co-administration of clopidogrel and esomeprazole should be under clinical monitoring and is not recommended in poor responders of antiplatelet therapy with clopidogrel.