CYP2C9 Alleles Research Articles

Effects of autologous platelet transfusion on platelet inhibition in ticagrelor‐treated and clopidogrel‐treated subjects

Background Antiplatelet agents increase bleeding risk. Few data on hemostatic benefits of platelet transfusion exist. Objective To assess the effect of autologous platelet transfusion on ticagrelor-mediated and clopidogrel-mediated platelet inhibition in a single-center, open-label, randomized, cross-over study (NCT01744288). Methods Forty-four healthy subjects received ticagrelor (180 mg) or clopidogrel (600 mg; two functional CYP2C19 alleles [*1 or *17] required) with or without platelet transfusion (14-day washout). Subjects received one autologous platelet apheresis unit (approximately six pooled donor platelet units) 24 h (n = 15) or 48 h (n = 13) after ticagrelor or 48 h after clopidogrel (n = 16). Platelet apheresis was conducted 72 h before transfusion. Aspirin (81 mg per day) was taken from after apheresis until 24 h before transfusion. P2Y12 reaction units (PRUs) and inhibition of platelet aggregation (IPA) induced by ADP were measured. Results Mean age and body mass index were 30 years (standard deviation [SD] 6 years) and 26.9 kg m-2 (SD 4.0 kg m-2 ), respectively; 98% of subjects were men, and 39 of 44 completed treatment. Platelet transfusion 24 h after ticagrelor had minimal effects on IPA or PRU values within 48 h after transfusion. Platelet transfusion 48 h after ticagrelor also had minimal effects on IPA or PRU values at most post-transfusion times. Platelet transfusion 48 h after clopidogrel, versus no transfusion, had a small reversing effect on IPA (24 h, 36 h, and 48 h) and PRU values (12 h, 24 h, and 36 h) after transfusion. Conclusions Autologous platelet transfusion is unlikely to be of clinical benefit in reversing the antiplatelet effects of ticagrelor. The clinical relevance of the small effects seen with clopidogrel is unknown.

Linkage disequilibrium between the CYP2C19*2,*17 and CYP2C9*1 alleles and impact of VKORC1, CYP2C9, CYP2C19 gene polymorphisms and gene-gene interactions on warfarin therapy.

Warfarin therapy is complicated by its large inter-individual and intra-individual variability. Both genetic and non-genetic factors can affect warfarin therapy. This study aims to investigate the allele distribution of VKORC1, CYP2C9 and CYP2C19, contribution of different allele variants and possible gene-gene interaction on warfarin therapy. Four hundreds and ninety-two patients were enrolled and single nucleotide polymorphisms for vitamin K epoxide reductase complex subunit 1 (VKORC1), cytochrome P450 CYP2C9 and cytochrome P450 CYP2C19 were genotyped. CYP2C9*1 allele is in complete linkage disequilibrium with CYP2C19*2 and CYP2C19*17 (D' = 1) in our study population. Patient with VKORC1-1639 G > A, CYP2C9*2 and CYP2C9*3 genetic variants need significant lower warfarin dose than patient with wild type allele of VKORC1 1639 G or CYP2C9*1. There is no significant differences between CYP2C19 allele variants for warfarin stable dose and INR > 5 event. Because of the complete linkage disequilibrium between CYP2C19*2,*17 and CYP2C9*1, patient with CYP2C19 *2/*2, *2/*17 and *17/*17 genotypes tend to have higher warfarin dose than patient with CYP2C19*1/*1 genotype. Stepwise regression analysis showed that VKORC1, CYP2C9, body mass index (BMI), age and gender were included as a factor significantly contributing to warfarin dose, whereas CYP2C19 did not contribute to warfarin dose. No statistically significant interaction between CYP2C9 and VKORC1 on warfarin dose and INR > 5 event was detected in univariate general linear model analysis. Our study suggests that polymorphic variants of VKORC1 and CYP2C9 affect warfarin dose independently, whereas CYP2C19 did not contribute to warfarin therapy.

CYP2C9 Genotype-Dependent Warfarin Pharmacokinetics: Impact of CYP2C9 Genotype on R- and S-Warfarin and Their Oxidative Metabolites.

Multiple factors can impact warfarin therapy, including genetic variations in the drug-metabolizing enzyme cytochrome P450 2C9 (CYP2C9). Compared with individuals with the wild-type allele, CYP2C9*1, carriers of the common *3 variant have significantly impaired CYP2C9 metabolism. Genetic variations in CYP2C9, the primary enzyme governing the metabolic clearance of the more potent S-enantiomer of the racemic anticoagulant warfarin, may impact warfarin-drug interactions. To establish a baseline for such studies, plasma and urine concentrations of R- and S-warfarin and 10 warfarin metabolites were monitored for up to 360 hours following a 10-mg warfarin dose in healthy subjects with 4 different CYP2C9 genotypes: CYP2C9*1/*1 (n = 8), CYP2C9*1/*3 (n = 9), CYP2C9*2/*3 (n = 3), and CYP2C9*3/*3 (n = 4). Plasma clearance of S-warfarin, but not R-warfarin, decreased multiexponentially and in a CYP2C9 gene-dependent manner: 56%, 70%, and 75% for CYP2C9*1/*3, CYP2C9*2/*3, and CYP2C9*3/*3 genotypes, respectively, compared with CYP2C9*1/*1, resulting in pronounced differences in the S:R ratio that identified warfarin-sensitive genotypes. CYP2C9 was the primary P450 enzyme contributing to S-warfarin metabolism and a minor contributor to R-warfarin metabolism. In the presence of a defective CYP2C9 allele, switching of warfarin metabolism to other oxidative pathways and P450 enzymes for the metabolic elimination of S-warfarin was not observed. The 10-hydroxywarfarin metabolites, whose detailed pharmacokinetics are reported for the first time, exhibited a prolonged half-life with no evidence of renal excretion and displayed elimination rate-limited kinetics. Understanding the impact of CYP2C9 genetics on warfarin pharmacokinetics lays the foundation for future genotype-dependent warfarin-drug interaction studies.

CYP2C9 and CYP2C19 Allele and Haplotype Distributions in Four Mestizo Populations from Western Mexico: An Interethnic Comparative Study.

Polymorphisms in the CYP2C9 and CYP2C19 genes confer potential risk for specific adverse drug reactions and therapeutic effect failure. Their frequencies differ among ethnic groups. This study was aimed to describe the distribution of CYP2C9 and CYP2C19 alleles and haplotypes in four Mestizo populations from Western Mexico and their comparison with the reported data from other ethnic groups. The CYP2C alleles (CYP2C9*2, CYP2C9*3, CYP2C19*2, and CYP2C19*3) were genotyped using polymerase chain reaction-restriction fragment length polymorphisms analyses using DNA samples from 477 healthy Mestizo individuals of Colima (n = 100), Jalisco (n = 147), Michoacán (n = 117), and Nayarit (n = 113). Frequencies ranged from 2.2-3.0% and 4.8-8.9% for CYP2C9*3 and CYP2C9*2 alleles, respectively, and 5.4-12.0% for CYP2C19*2, whereas the CYP2C19*3 allele was not found. Haplotype GACA, which harbors the loss-of-function allele CYP2C19*2, was the second most frequent (8.7%). Genetic heterogeneity between the Western Mexican populations studied here and the global population was evident (p < 0.05), except for most American populations and other Mexican Mestizo populations. Our findings increase the evidence for genetic variability at relevant pharmacogenetic loci and could be useful in association studies involving drugs that are substrates for CYP2C enzymes in the Western Mexican population.

Pharmacokinetics of Bupropion and Its Pharmacologically Active Metabolites in Pregnancy

Bupropion sustained release is used to promote smoking cessation in males and nonpregnant females. However, its efficacy as a smoking cessation aid during pregnancy is not reported. The pregnancy-associated changes in maternal physiology may alter the pharmacokinetics and pharmacodynamics of bupropion and consequently its efficacy in pregnant smokers. Therefore, the aims of this study were to determine the steady-state pharmacokinetics of bupropion during pregnancy and the effect of functional genetic variants of CYP2B6 and CYP2C19 on bupropion pharmacokinetics in pregnant women. Plasma and urine concentrations of bupropion and its metabolites hydroxybupropion (OHBUP), threohydrobupropion, and erythrohydrobupropion were determined by liquid chromatography-mass spectrometry. Subjects were genotyped for five nonsynonymous single-nucleotide polymorphisms that result in seven CYP2B6 alleles, namely *2, *3, *4, *5, *6, *7, and *9, and for CYP2C19 variants *2, *3, and *17 The present study reports that the isoform-specific effect of pregnancy on bupropion-metabolizing enzymes along with the increase of renal elimination of the drug could collectively result in a slight decrease in exposure to bupropion in pregnancy. In contrast, pregnancy-induced increase in CYP2B6-catalyzed bupropion hydroxylation did not impact the plasma levels of OHBUP, probably due to a higher rate of OHBUP glucuronidation, and renal elimination associated with pregnancy. Therefore, exposure to OHBUP, a pharmacologically active metabolite of the bupropion, appears to be similar to that of the nonpregnant state. The predicted metabolic phenotypes of CYP2B6*6 and variant alleles of CYP2C19 in pregnancy are similar to those in the nonpregnant state.

Relevance of the ancestry for the variability of the Drug-Metabolizing Enzymes CYP2C9, CYP2C19 and CYP2D6 polymorphisms in a multiethnic Costa Rican population.

CYP2C9, CYP2C19 and CYP2D6 metabolize around 40% of drugs and their genes vary across populations. The Costa Rican population has a trihybrid ancestry and its key geographic location turns it into a suitable scenario to evaluate interethnic differences across populations. This study aims to describe the diversity of CYP2C9, CYP2C19 and CYP2D6 polymorphisms in Costa Rican populations in the context of their ancestry. A total of 448 healthy individuals were included in the study: Bribri (n= 47), Cabécar (n= 27), Maleku (n= 16), Guaymí (n= 30), Huetar (n= 48), Chorotega (n= 41), Admixed/Mestizos from the Central Valley/Guanacaste (n= 189), and Afro-Caribbeans (n= 50) from Limón. CYP2C9 (alleles *2, *3, *6) and CYP2C19 (*2, *3, *4, *5, *17) genotypes were determined by Real-Time PCR. African, European and Native American ancestry were inferred using 87 ancestry informative markers. The frequency of the decreased activity allele CYP2C9*2 is lower in the self-reported Amerindian groups compared to the admixed population, and the highest frequencies of CYP2C19*2 (null activity) and the CYP2C19*17 (increased activity) were found in the self-reported Afro-Caribbean population. Moreover, a frequency of 0.7 % CYP2C9 gPMs in the Admixed population and a variable frequency of CYP2C19 gUMs (0.0-32.6 %, more prevalent in Afro-Caribbeans) in Costa Rican populations, was found. Finally, the following alleles were positively correlated with genomic African ancestry and negatively correlated with genomic Native American ancestry: CYP2D6*5 (null activity), CYP2D6*17 (decreased activity), CYP2D6*29 (decreased activity) and CYP2C19*17 (increased activity). No correlation for CYP2C9 polymorphisms and genomic ancestry was found. Further studies assessing the CYP2C9 and CYP2C19 sequence in these populations, preferentially by sequencing these genes, are warranted.

Distribution of polymorphisms in the CYP2C9 gene and CYP2C19/CYP2C9 haplotypes among Venezuelan populations

Background: Polymorphisms with decreased enzyme activity of their gene products have been reported in region CYP2C with population variations in haplotype structure.Aim: To estimate the allelic and genotypic frequencies of variants CYP2C9*2 and CYP2C9*3 and of CYP2C9/CYP2C19 haplotypes in Venezuelan populations.Subjects and methods: Six hundred and thirty-four individuals from nine admixed populations (AP) and the Warao indigenous group were studied. Allelic frequencies, linkage disequilibrium and genetic distances for haplotypes were calculated and compared within Venezuela and with data available in the literature.Results: Heterogeneity in the distribution of CYP2C9 alleles and CYP2C9/CYP2C19 haplotypes among the AP and the Warao was observed. The joint frequency of haplotypes, with at least one non-functional variant, shows values in AP between 21–41%, while in Warao it reaches 5%. The haplotype that includes the Asian and rare Latin America CYP2C19*3 allele was detected in most AP and in Warao. Pairwise Fst values showed that the Warao was an outlier compared with the AP, while these are closer to European-derived populations. No significant correlation was found between haplotype frequencies and admixture.Conclusions: These results support the need to understand the distribution of genomic biomarkers related to the metabolism of drugs, for planning national public health strategies.

Impact of CYP2C19 Polymorphisms on Clinical Outcomes and Antiplatelet Potency of Clopidogrel in Caucasian Poststroke Survivors.

Variable response after clopidogrel is well documented and may affect major adverse clinical events after stroke. Impact of CYP2C19 genetic polymorphisms is an established marker linked to variable response after clopidogrel. However, the association of certain genetic polymorphisms with prediction of major adverse clinical events following stroke still remains controversial, especially in Caucasians. The primary aim was to evaluate the impact of CYP2C19 allele *2 in heterozygote form on major adverse clinical events in Caucasian poststroke survivors treated with clopidogrel. The secondary aim was to analyze the potential link between CYP2C19 genetic polymorphism and variable response after clopidogrel. One hundred thirty patients of Caucasian origin following documented ischemic stroke were included. Platelet reactivity was assessed by light transmittance aggregometry (LTA) and matched with various CYP2C19 loss-of-function genetic polymorphisms and major adverse clinical events (composite of vascular deaths, stroke/transient ischemic attack, and myocardial infarction). Over the mean follow-up of 14.9 months, 19 patients experienced major adverse clinical events. The risk of major adverse clinical events was nearly 3-fold in loss-of-function allele carriers (hazard ratio = 2.904; 95% confidence interval, 1.083-7.786; P = 0.013), whereas the risk of ischemic stroke or transient ischemic attack alone was also higher (hazard ratio = 3.170; 95% confidence interval, 1.281-7.849; P = 0.034). Platelet activity was strongly associated with allele *2 status (rs = 0.21, P = 0.016) but not with other genetic polymorphisms. Carriers of allele*2 exhibited lower platelet response to adenosine diphosphate-mean LTA (30.1% vs. 42.0%; P = 0.017). There were no significant differences in LTA results with other agonists. Strong association of increase in adenosine diphosphate-induced aggregation with diabetes mellitus (rs = 0.20, P = 0.023), increasing age (rs = 0.23, P = 0.008), and conversely diminishing over increased weight (rs = 0.23, P = 0.009) was also detected. The carriers of other gene allele variants lack uniformed impact on variable response after clopidogrel. Even heterozygous CYP2C19*2 allele carriers among Caucasian patients after ischemic stroke had a higher risk of major adverse clinical events. The LTA, however, did not predict major adverse clinical events. The exact clinical utility of these findings is still uncertain and requires large outcome-driven randomized trial in Caucasians for proof of concept.

Effects of CYP2C19 variants on methadone metabolism in vitro

CYP2C19 is an important member of the cytochrome P450 (CYP450) enzyme super family and is responsible for clearing approximately 10% of commonly used clinical drugs that undergo phase I metabolism. Genetic polymorphisms of CYP2C19 significantly influence the efficacy and safety of some drugs, which might cause undesirable adverse effects or cure failure at standard dosages. The aim of this study was to clarify the catalytic activities of 31 CYP2C19 alleles on the oxidative in vitro metabolism of methadone. Insect microsomes expressing the CYP2C19 alleles were incubated with 50-2000 μM methadone for 30 min at 37 °C and terminated by cooling to -80 °C immediately. Methadone and its metabolite EDDP were analyzed by an ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) system. Of the 31 tested CYP2C19 allelies variants, CYP2C19*1 is the wild-type. Compared with CYP2C19*1, two CYP2C19 variants (CYP2C19*3 and *35FS) had no detectable enzyme activity, one variant L16F exhibited slightly increased intrinsic clearance values, and one variant N277K showed no significant difference. In addition, 26 variants exhibited significantly decreased values (from 1.48% to 80.40%). These findings suggest that more attention should be paid in clinical administration of methadone to individuals carrying these CYP2C19 alleles. Copyright © 2016 John Wiley & Sons, Ltd.

In vitro metabolism of phenytoin in 36 CYP2C9 variants found in the Chinese population

Cytochrome P450 2C9 (CYP2C9) is an important member of the cytochrome P450 enzyme superfamily, with 57 CYP2C9 allelic variants being previously reported. Recently, we identified 22 novel alleles (*36 -*56 and N418T) in the Han Chinese population. This study aims to assess the catalytic activities of wild-type (CYP2C9*1) and 36 CYP2C9 allelic variants found in the Chinese population toward phenytoin (PHT) in vitro. Insect microsomes expressing CYP2C9*1 and 36 CYP2C9 variants were incubated with 1–200 μM phenytoin for 30 min at 37 °C. Then, these products were extracted and the signal detection was performed by HPLC-MS/MS. The intrinsic clearance (Vmax/Km) values of all variants, with the exception of CYP2C9*2, CYP2C9*11, CYP2C9*23, CYP2C9*29, CYP2C9*34, CYP2C9*38, CYP2C9*44, CYP2C9*46 and CYP2C9*48, were significantly different from CYP2C9*1. CYP2C9*27, *40, *41, *47, *49, *51, *53, *54, *56 and N418T variant exhibited markedly larger values than CYP2C9*1 (>152.8%), whereas 17 variants exhibited smaller values (from 48.6% to 99.9%) due to larger Km and/or smaller Vmax values than CYP2C9*1. The findings suggest that more attention should be paid on subjects carrying these infrequent CYP2C9 alleles when administering phenytoin in clinic.

Simultaneous subacute coronary artery stent thrombosis in a carrier of two CYP2C19 loss–of function polymorphisms (*2/*3)

Simultaneous subacute coronary artery stent thrombosis in a carrier of two CYP2C19 loss–of function polymorphisms (*2/*3)

Association of Genetic Polymorphisms in the VKORC1 and CYP2C9 Genes with Warfarin Dosage in a Group of Kuwaiti Individuals

Warfarin is the most widely prescribed oral anticoagulant worldwide. The narrow therapeutic index and the large variation in the inter-individual dose of warfarin are problematic, since the side effects can be lethal. Single nucleotide polymorphisms (SNP) in CYP2C9 and VKORC1 have been shown to significantly affect warfarin dosage toleration and this effect varies among different populations. We aimed to investigate the effect of these SNPs on warfarin dosage in a sample of Kuwaiti patients. Kuwaiti patients who were taking a maintenance dose of warfarin were genotyped for CYP2C9*1, *2 and *3 and VKORC1 rs9923231, rs9934438, rs7294 and rs2884737. The association of these SNPs with the warfarin dose was evaluated. For CYP2C9, the CYP2C9 *1/*1 genotype required a higher dose (5.5 ± 3.3 mg/day) compared to non-*1/*1 (3.3 ± 1.7 mg/day) (p = 0.003). For VKORC1, the daily warfarin dose was significantly different (p = 0.001) among the three genotypes of rs9923231, rs9934438 and rs2884737, with carriers of the wild-type genotype requiring the highest dose compared to variant allele carriers (p ≤ 0.001-0.002). There was no association found between the daily warfarin dose and the rs7294 polymorphism. Our data showed that individuals carrying the wild-type allele of CYP2C9 or VKORC1 rs9923231, rs9934438 or rs2884737 are less sensitive than individuals with the variant alleles of these SNPs and therefore required a higher daily maintenance dose of warfarin. Our study confirms the association between SNPs in CYP2C9 and VKORC1 and warfarin dose tolerance in Kuwaiti patients.

Non-Carriers of Reduced-Function CYP2C19 Alleles are Most Susceptible to Impairment of the Anti-Platelet Effect of Clopidogrel by Proton-Pump Inhibitors: A Pilot Study.

The phenomenon of CYP2C19 polymorphism affects the metabolism of both clopidogrel and proton-pump inhibitors (PPI). However, concomitant use of both drugs may reduce the desired therapeutic effects. In this study, we evaluated whether individuals with different numbers of reduced-function CYP2C19 alleles were equally affected and whether PPIs with different dependencies on CYP2C19 metabolism were equally involved. Thirty healthy volunteers were recruited to a six-week regimen of clopidogrel. Three PPIs with different metabolic dependencies on CYP2C19 were included and separately administered in this order. Each PPI was given for a week, followed by a one-week washout period before the intervention of the next PPI. The anti-platelet effect was examined by Thromboelastography Platelet Mapping(TM) (TEG®) and vasodilator-stimulated phosphoprotein (VASP) assays. Both TEG® and VASP tests showed the same general qualitative trend, but TEG® detected a statistically significant fluctuation of platelet aggregation in response to different drug interventions. The TEG® results also demonstrated that non-carriers experienced the most significant impairment of anti-platelet effect of clopidogrel after concomitant use of PPIs. This impairment was closely related to the metabolic dependence on CYP2C19 of PPI. Our study indicated that non-carriers of reduced-function CYP2C19 alleles are most susceptible to impairment of the anti-platelet effect of clopidogrel after concomitant PPI use. Individual subjects are not equally affected, and PPIs are not equally involved. However, large-scale randomized clinical trials are needed to evaluate the clinical outcome. Clopidogrel • CYP2C19 polymorphism • Platelet aggregation • Proton pump inhibitors • TEG • VASP.

Association of Genetic Polymorphisms of CYP2C9 and VKORC1 with Bleeding Following Warfarin: A Case-Control Study.

Various factors have been shown to increase the risk of bleeding with warfarin. This study aimed to assess the association of CYP2C9 and VKORC1 with the development of bleeding following warfarin. A case control study was initiated after obtaining institutional ethics committee clearance and written informed consent from patients. Cases were defined as those who bled within three months of warfarin initiation and controls as those who did not have any episode of bleeding within three months. Genotyping for CYP2C9 (*1, *2, *3) and VKORC1 1639 (GG, GA and AA) was performed by PCRRFLP. Chi square test was used to find out the association and trend of CYP2C9 and VKORC1 genotypes with odds ratio (95% CI) for strength of association. A binary logistic regression model was developed associating age, body weight, sex, CYP2C9 and VKORC1 status with risk of bleeding. A total of 100 controls and 38 cases were studied from Oct 2009 to July 2011. A significant association (P < 0.0001) and trend (P = 0.027) of mutant alleles of CYP2C9 and VKORC1 were noted with bleeding with odds ratios of 7.8 [3.4, 17.9] and 2.7 [1.3, 5.7] respectively. Weekly dose requirement was significantly lower with the presence of *3 allele relative to *1 in CYP2C9 (P < 0.001). The regression model showed an accuracy of 80% and could explain 35.3% of the variability. A significant association between CYP2C9 (*1,*2,*3) genotype and VKORC1 (1639 G>A) haplotype status has been found with increased bleeding tendency to warfarin. This may help to individualize therapy.

Pharmacogenetic Testing for Analgesic Adverse Effects: Pediatric Case Series.

Genetic variants in pharmacokinetic genes can alter the effectiveness and increase the risks of using analgesics to treat pain. The purpose of this retrospective study is to describe the clinical experiences that led to pharmacogenetic testing of pediatric pain management program patients for alterations in the CYP2D6, CYP2C19, and CYP2C9 genes and correlate the analgesic efficacy and adverse analgesic effects with the gene-specific findings and Metabolic Reserve (MR) index. Nineteen patients were referred for pharmacogenetic testing between February 2010 and December 2013 due to analgesic ineffectiveness or adverse analgesic effects. CYP2D6, CYP2C19, and CYP2C9 functional status was inferred from genotyping; and MR calculated. Data from the available inpatient and outpatient medical records from January 2007 to May 2014 for these patients were reviewed and extracted to characterize patient analgesic response phenotype. Significant CYP2D6 genetic variants were identified in 16 of the 19 (84%) patients: 4 were ultra-rapid metabolizers, 8 were deficient, 3 were poor metabolizers, and 1 was CYP2D6 null metabolizer. Of the 3 patients with functional CYP2D6 status, 2 were CYP2C19 null metabolizers. The MR scores ranged from 3.0 to 7.0, with a bimodal distribution with high frequencies corresponding to 4.0/4.5 and 7.0. Clinical evaluation of analgesic ineffectiveness and adverse effects led to the high likelihood of identifying patients with CYP2D6, CYP2C19, and CYP2C9 alleles associated with alterations in analgesic metabolism. Further research is needed to integrate pharmacogenetic and clinical information into anticipatory guidance for pharmacogenetic testing and analgesic prescribing to children with pain.

Impact of Cytochrome P450 2C19*2 and *3 on Clopidogrel Loading Dose in Saudi Patients with Acute Coronary Syndrome.

Background: Emerging evidence shows that clopidogrel is greatly affected by non-functioning alleles measured by P2Y12 or platelet reactivity units (PRU). Cardiac events during short in-hospital stays have been inconclusively suggested as the main causes of discrepancies. Objectives: Evaluate the impact of CYP2C19 allele * 2 and allele * 3 on PRU and the potential clinical consequences of such interaction. To establish a rough estimation for the safe PRU limits for short in-hospital stay following PCI. Method: A short-term experimental study was conducted with 90 patients who underwent coronary angioplasty with drug eluting stents at the Prince Sultan Cardiac Center, Buraidah. All the patients received an initial loading dose of 300 mg clopidogrel, followed by 75 mg daily. Blood samples were used for DNA extraction for cytochrome P450 (CYP) and real-time polymerase chain reaction (PCR) was used for genotyping. PRU and inhibition rate were tested by Verifynow®. All in-hospital cardiac events were recorded until patients were discharged. Results: Genotypes 1/1, 2/2, and 1/2 were expressed by 60, 28, and two patients (67, 32, and 3%), respectively. The PRU of the female patients was significantly higher than that of the male patients was (255.6 ± 68.8 and 177.7 ± 66.6, p = 0.000, respectively). There was no significant difference in PRUs (193 ± 79 and 212 ±55.4, respectively, p = 0.349), nor inhibition (17.9 ± 18.80 and 13.88 ± 11.5, p = 0.135) in wild and resistant variants, respectively. We only reported one cardiac in-thrombosis events. Conclusion: Genotype differences may not explain variations in the PRU of patients during short-term in-hospital stays. Although it is difficult to confirm, 117–267 units may be a safe PRU range for such patients, with emphasis on attaining higher PRU values in females.

Genotype Frequencies of CYP2C19, P2Y12 and GPIIIa Polymorphisms in Coronary Heart Disease Patients of Han Ethnicity, and Their Impact on Clopidogrel Responsiveness.

To investigate the genotype frequencies of cytochrome P450, family2, subfamily C, polypeptide19 (CYP2C19); P2Y12 receptor; and glycoprotein IIIa polymorphisms in patients with coronary heart disease and their impact on clopidogrel responsiveness and major adverse cardiac events (MACEs).A total of 146 coronary heart disease patients of Han ethnicity, on a clopidogrel regimen, were enrolled. Polymerase chain reaction and DNA sequencing were used to detect the genotype and allelic frequencies of CYP2C19 ((*)2,(*)3,(*)17), P2Y12 (C34T, G52T, T744C) and GPIIIa (T1565C) polymorphisms. Clinical and laboratory data were compared between the high on-treatment platelet reactivity (HTPR) versus normal groups.HTPR was identified in 35 (24%) patients. CYP2C19(*)2 (G681A) polymorphism was found to be significantly associated with HTPR (P < 0.05). A allele frequencies were significantly higher in the HTPR group versus the normal group (P < 0.05). On logistic regression analysis, CYP2C19(*)2 (G681A) polymorphism was found to be an independent risk factor associated with HTPR. No link could be established between genetic polymorphisms and recurrence of MACEs, or between HTPR and recurrence of MACEs.The genetic polymorphisms in CYP2C19(*)2 were closely associated with HTPR. The frequency of the A allele of CYP2C19(*)2 was significantly associated with HTPR, with A allele carriers being more likely to develop HTPR.

Association between high on-treatment platelet reactivity and occurrence of cerebral ischemic events in patients undergoing percutaneous coronary intervention

IntroductionPercutaneous coronary angioplasty (PCI) has become a routine treatment in symptomatic patients with coronary artery disease. The use of new generation drug eluting stents (DES) and dual antiplatelet therapy has significantly improved treatment outcomes and increased patients' safety by reducing the risk of stent thrombosis. AimsThe goal of this study was to assess whether high on treatment platelet reactivity (HTPR), despite clopidogrel treatment, measured with Multiplate Electrode Aggregometer (MEA) is associated with the risk of adverse ischemic cerebral events. MethodsSymptomatic patients with coronary artery disease admitted for coronary angiography and angioplasty (PCI) were consecutively enrolled in this study. 249 consecutive patients underwent coronary artery stenting for stable angina (n=215) or non-ST-elevation acute coronary syndrome (n=34). Inhibition of platelet aggregation was assessed by MEA. Genetic polymorphism of CYP2C19 was tested by HRM Real-Time PCR method in 150 patients. ResultsPatients with HTPR were more frequently diagnosed with ischemic stroke (p=0.0351, OR=16.818, 95% CI [1.464–193.23]) and other ischemic cerebral events (stroke or TIA, p=0.0339, OR=6.5, 95% CI [1.36–31.07]). Cumulative assessment of all ischemic and hemorrhagic events showed no statistical significance. Cerebral ischemic event was the only adverse event that correlated with CYP2C19 (*2/*2) allele (p=0.0489, OR=10; 95% CI [1.39–71.80]). ConclusionsHTPR assessed by MEA, in patients treated with clopidogrel after coronary artery stenting was found to be an important risk factor of ischemic cerebral events. In concordance, the carriers of CYP2C19*2/*2 allele showed an increased rate of ischemic cerebral events.

Pharmacogenetic testing in population of South Ural

Drug resistance is a phenomenon that has received serious attention in recent years in everyday medical practice. This may also be described as responsiveness or non-responsiveness to drugs, as patients respond partially to medical treatment or have no response at all [1]. The non-responsiveness to clopidogrel in cardiac patients of different populations is due to genetic variations in the cytochrome P450 (CYP) gene [2]. Carriers of at least one 'poor metabolizer allele' of CYP2C19 (either *2 or *3) have lower levels of the active metabolite of clopidogrel and have reduced platelet inhibition [3]. Furthermore, the significant inter-ethnic variability in the allelic frequencies of CYP2C19*2 has been associated with differential clopidogrel resistance [4]. Such mutations in this variant allele are responsible for the inability of the CYP enzyme to convert clopidogrel into its active metabolite, which may result in the increased risk of death, heart attack or stroke among patients who have undergone percutaneous coronary intervention (PCI) [5]. South Ural is a multinational region, a subject of the Russian Federation, where genetic variations have not been studied fully yet. To examine prevalence of mutant alleles in population of South Ural. We conducted pharmacogenetic testing for specific single nucleotide polymorphisms in 54 patients. The present research was conducted in the alleles CYP2C19*2 and CYP2C19*3. The data were processed using the program SPSS Statistics. The mean age of patients was 58, 4 years (from 26 to 79 years). Among all patients 59.3% were male, 40.7% of female patients.Among the studied patients in allele CYP2C19*2, the "wild" type GG was detected in 75,9% of patients, GA type in 22.2% and AA variant was detected in 1.9% of all patients. Allele CYP2C19*3 is often found among alleles with reduced function and also associated with resistance to clopidogrel. Functional drug response is observed in patients with type GG. All of the studied patients were carriers of this type. According to literature data the frequency of genotypes associated with resistance to clopidogrel in the Russian population is 11.4%, which is comparable with European ethnic groups [6]. It was revealed that 75,9% of patients were sensitive to clopidogrel, and for them this drug in its standard dosage will be effective, and 24,1% of patients were not sensitive, therefore, they would require replacement of clopidogrel with another drug.

Genetic polymorphisms analysis of drug-metabolizing enzyme CYP2C9 in the Uyghur population

Genetic variations in cytochrome P450 2C9 are known to contribute to interindividual and interethnic variability in response to clinical drugs, but little is known about the genetic variation of CYP2C9 in the Uyghur population.We directly sequenced the whole CYP2C9 gene in 96 unrelated, healthy Uyghur from Xinjiang Uygur Autonomous Region of China and screened for genetic variants in the promoter, exons, introns and 3′-UTR.Thirty five previously reported alleles and six genotypes were detected in this study. The allele frequencies of CYP2C9*1, *2, *11, *12, *29 and *33 were 89.58, 7.81, 0.52, 0.52, 1.04 and 0.52%, respectively. We detected one non-synonymous novel variant at position 329 from Arg to Cys and this mutation is predicted to be intolerant by SIFT.Our results provide basic information about CYP2C9 alleles in Uyghur, which may help to optimize pharmacotherapy effectiveness by providing personalized medicine to this ethnic group.