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CYP2C19 Genotype-Guided Antiplatelet Therapy Among Asian Patients with Ischaemic Stroke

Kow CS, Zaihan AF, Hasan SS

Clin Drug Investig, 2021 01;41(1):115-116.
PMID: 33237558 DOI: 10.1007/s40261-020-00985-5
Matched MeSH terms: Cytochrome P-450 CYP2C19/genetics
Choice of PCR microtube can impact on the success of long-range PCRs

Chua EW, Miller AL, Kennedy MA

Anal Biochem, 2015 May 15;477:115-7.
PMID: 25766577 DOI: 10.1016/j.ab.2015.02.023

We compared four brands of microtubes with respect to their suitability for long-range polymerase chain reactions (PCRs). One of the four brands was found to have an inhibitory effect, decreasing PCR yields. The effect was universal across different PCR or enzyme systems. Increased ultraviolet absorbance suggests leaching of unknown chemical species into PCR mixtures. However, this could not be confirmed by high-performance liquid chromatography-mass spectrometry analysis. Nevertheless, our article demonstrates a clear impact of the choice of microtubes on long-range PCR success. Due consideration should be given to the PCR microtubes when determining optimal reaction conditions for long-range PCR.

Matched MeSH terms: Cytochrome P-450 CYP2C19/genetics
In Vitro Functional Characterisation of Cytochrome P450 (CYP) 2C19 Allelic Variants CYP2C19*23 and CYP2C19*24

Lau PS, Leong KV, Ong CE, Dong AN, Pan Y

Biochem Genet, 2017 Feb;55(1):48-62.
PMID: 27578295 DOI: 10.1007/s10528-016-9771-8

Cytochrome P450 (CYP) 2C19 is essential for the metabolism of clinically used drugs including omeprazole, proguanil, and S-mephenytoin. This hepatic enzyme exhibits genetic polymorphism with inter-individual variability in catalytic activity. This study aimed to characterise the functional consequences of CYP2C19*23 (271 G>C, 991 A>G) and CYP2C19*24 (991 A>G, 1004 G>A) in vitro. Mutations in CYP2C19 cDNA were introduced by site-directed mutagenesis, and the CYP2C19 wild type (WT) as well as variants proteins were subsequently expressed using Escherichia coli cells. Catalytic activities of CYP2C19 WT and those of variants were determined by high performance liquid chromatography-based essay employing S-mephenytoin and omeprazole as probe substrates. Results showed that the level of S-mephenytoin 4'-hydroxylation activity of CYP2C19*23 (V max 111.5 ± 16.0 pmol/min/mg, K m 158.3 ± 88.0 μM) protein relative to CYP2C19 WT (V max 101.6 + 12.4 pmol/min/mg, K m 123.0 ± 19.2 μM) protein had no significant difference. In contrast, the K m of CYP2C19*24 (270.1 ± 57.2 μM) increased significantly as compared to CYP2C19 WT (123.0 ± 19.2 μM) and V max of CYP2C19*24 (23.6 ± 2.6 pmol/min/mg) protein was significantly lower than that of the WT protein (101.6 ± 12.4 pmol/min/mg). In vitro intrinsic clearance (CLint = V max/K m) for CYP2C19*23 protein was 85.4 % of that of CYP2C19 WT protein. The corresponding CLint value for CYP2C19*24 protein reduced to 11.0 % of that of WT protein. These findings suggested that catalytic activity of CYP2C19 was not affected by the corresponding amino acid substitutions in CYP2C19*23 protein; and the reverse was true for CYP2C19*24 protein. When omeprazole was employed as the substrate, K m of CYP2C19*23 (1911 ± 244.73 μM) was at least 100 times higher than that of CYP2C19 WT (18.37 ± 1.64 μM) and V max of CYP2C19*23 (3.87 ± 0.74 pmol/min/mg) dropped to 13.4 % of the CYP2C19 WT (28.84 ± 0.61 pmol/min/mg) level. Derived from V max/K m, the CLint value of CYP2C19 WT was 785 folds of CYP2C19*23. K m and V max values could not be determined for CYP2C19*24 due to its low catalytic activity towards omeprazole 5'-hydroxylation. Therefore, both CYP2C19*23 and CYP2C19*24 showed marked reduced activities of metabolising omeprazole to 5-hydroxyomeprazole. Hence, carriers of CYP2C19*23 and CYP2C19*24 allele are potentially poor metabolisers of CYP2C19-mediated substrates.

Matched MeSH terms: Cytochrome P-450 CYP2C19/genetics*
Fulltext Prevalence of the CYP2C19*2 (681 G>A), *3 (636 G>A) and *17 (‑806 C>T) alleles among an Iranian population of different ethnicities

Dehbozorgi M, Kamalidehghan B, Hosseini I, Dehghanfard Z, Sangtarash MH, Firoozi M, et al.

Mol Med Rep, 2018 03;17(3):4195-4202.
PMID: 29328413 DOI: 10.3892/mmr.2018.8377

Polymorphisms in the cytochrome P (CYP) 450 family may cause adverse drug responses in individuals. Cytochrome P450 2C19 (CYP2C19) is a member of the CYP family, where the presence of the 681 G>A, 636 G>A and 806 C>T polymorphisms result in the CYP2C19*2, CYP2C19*3 and CYP2C19*17 alleles, respectively. In the current study, the frequency of the CYP2C19*2, CYP2C19*3 and CYP2C19*17 alleles in an Iranian population cohort of different ethnicities were examined and then compared with previously published frequencies within other populations. Allelic and genotypic frequencies of the CYP2C19 alleles (*2, *3 and *17) were detected using polymerase chain reaction (PCR)‑restriction fragment length polymorphism analysis, PCR‑single‑strand conformation polymorphism analysis and DNA sequencing from blood samples of 1,229 unrelated healthy individuals from different ethnicities within the Iranian population. The CYP2C19 allele frequencies among the Iranian population were 21.4, 1.7, and 27.1% for the CYP2C19*2, CYP2C19*3 and CYP2C19*17 alleles, respectively. The frequency of the homozygous A/A variant of the CYP2C19*2 allele was significantly high and low in the Lur (P<0.001) and Caspian (P<0.001) ethnicities, respectively. However, the frequency of the homozygous A/A variant of the CYP2C19*3 allele was not detected in the Iranian cohort in the current study. The frequency of the heterozygous G/A variant of the CYP2C19*3 allele had the significantly highest and lowest frequency in the Fars (P<0.001) and Lur (P<0.001) groups, respectively. The allele frequency of the homozygous T/T variant of the CYP2C19*17 allele was significantly high in the Caspian (P<0.001) and low in the Kurd (P<0.05) groups. The frequency of the CYP2C19 alleles involved in drug metabolism, may improve the clinical understanding of the ethnic differences in drug responses, resulting in the advancement of the personalized medicine among the different ethnicities within the Iranian population.

Matched MeSH terms: Cytochrome P-450 CYP2C19/genetics*
Late stent thrombosis in a patient with CYP2C19*3/*17 genotype and clopidogrel high on-treatment platelet reactivity

Tan SSN, Koh KT, Tiong LL, Ong TK, Fong AYY

Pharmacogenomics, 2018 10;19(15):1151-1157.
PMID: 30191759 DOI: 10.2217/pgs-2018-0082

AIM: Recurrent thrombotic events still occur despite dual antiplatelet therapy in patient's post percutaneous coronary intervention (PCI) could be attributed to high on-treatment platelet reactivity.
METHODS: A 44-year-old male, who had staged PCI to left anterior descending (LAD) 2 weeks after an anterior MI, with a drug-coated stent was readmitted with new anterior STEMI 35 days later. Coronary angiogram revealed mid-stent thrombus in situ. He had further uncomplicated PCI. Platelet function testing and genotyping showed clopidogrel high on-treatment platelet reactivity and CYP2C19*3/*17 genotype. Ticagrelor was commenced.
RESULTS & CONCLUSION: This case study is the first reported in Malaysia to document a patient with a CYP2C19*3/*17 genotype presenting with a stent thrombosis after an uncomplicated index PCI procedure.

Matched MeSH terms: Cytochrome P-450 CYP2C19/genetics*
The effect of CYP2C19 genetic polymorphism and non-genetic factors on clopidogrel platelets inhibition in East Asian coronary artery disease patients

Amin AM, Sheau Chin L, Mohamed Noor DA, Mostafa H, Abdul Kader MASK, Kah Hay Y, et al.

Thromb Res, 2017 10;158:22-24.
PMID: 28802144 DOI: 10.1016/j.thromres.2017.07.032
Matched MeSH terms: Cytochrome P-450 CYP2C19/genetics*
Site-Directed Mutagenesis of Cytochrome P450 2D6 and 2C19 Enzymes: Expression and Spectral Characterization of Naturally Occurring Allelic Variants

Dong AN, Pan Y, Palanisamy UD, Yiap BC, Ahemad N, Ong CE

Appl Biochem Biotechnol, 2018 Sep;186(1):132-144.
PMID: 29524040 DOI: 10.1007/s12010-018-2728-0

Genetic polymorphism of the cytochrome P450 (CYP) genes particularly affects CYP2D6 and CYP2C19 to a functionally relevant extent, and it is therefore crucial to elucidate the enzyme kinetic and molecular basis for altered catalytic activity of these allelic variants. This study explored the expression and function of the reported alleles CYP2D6*2, CYP2D6*10, CYP2D6*17, CYP2C19*23, CYP2C19*24, and CYP2C19*25 with respect to gene polymorphisms. Site-directed mutagenesis (SDM) was carried out to generate these six alleles. After DNA sequencing, the CYP2D6 and CYP2C19 wild types alongside with their alleles were each independently co-expressed with NADPH-CYP oxidoreductase (OxR) in Escherichia coli. The expressed proteins were analyzed using Western blotting, reduced carbon monoxide (CO) difference spectral scanning, and cytochrome c reductase assay. Results from Western blot revealed the presence of all CYP wild-type and allelic proteins in E. coli membrane fractions. The reduced CO difference spectra scanning presented the distinct peak of absorbance at 450 nm, and the cytochrome c reductase assay has confirmed that spectrally active OxR was expressed in each protein preparation. As a conclusion, the results obtained from this study have proven the CYP variants to be immunoreactive and spectrally active and are suitable for use to examine biotransformation and interaction mechanism of the enzymes.

Matched MeSH terms: Cytochrome P-450 CYP2C19/genetics*
Association of CYP2C19*2 polymorphism with clopidogrel response and 1-year major adverse cardiovascular events in a multiethnic population with drug-eluting stents

Tan SSN, Fong AYY, Mejin M, Gerunsin J, Kong KL, Chin FYY, et al.

Pharmacogenomics, 2017 08;18(13):1225-1239.
PMID: 28745576 DOI: 10.2217/pgs-2017-0078

BACKGROUND: Patients undergoing elective percutaneous coronary intervention (PCI) with drug-eluting stents (DES) who have impaired clopidogrel response, have a higher risk of subsequent major adverse cardiovascular events (MACE).
AIM OF THE STUDY: To establish the relationship between CYP2C19 genotype, clopidogrel responsiveness and 1-year MACE.
MATERIALS & METHODS: Aspirin/clopidogrel responses were assessed with Multiplate Analyzer and CYP2C19*2 allele by SpartanRx.
RESULTS: A total of 42.0% carried ≥1 CYP2C19*2 allele. Prevalences of aspirin and clopidogrel high on-treatment platelet reactivity (HPR; local cutoffs: 300 AU*min for aspirin and 600 AU*min for clopidogrel) were 11.5% and 19.8% respectively. In multivariate ana-lysis, clopidogrel HPR was found to be an independent predictor for 1-year MACE (adj HR: 3.48, p = 0.022 ).
CONCLUSION: Having clopidogrel HPR could be a potentially modifiable risk factor guided by phenotyping.

Matched MeSH terms: Cytochrome P-450 CYP2C19/genetics*
Polymorphisms in the host CYP2C19 gene and antibiotic-resistance attributes of Helicobacter pylori isolates influence the outcome of triple therapy

Ram M R, Teh X, Rajakumar T, Goh KL, Leow AHR, Poh BH, et al.

J Antimicrob Chemother, 2019 01 01;74(1):11-16.
PMID: 30403784 DOI: 10.1093/jac/dky401

Objectives: Eradication of Helicobacter pylori is influenced by susceptibility to antimicrobial agents, elevated bacterial load and degree of acid inhibition, which can be affected by genotypes of drug-metabolizing enzymes [cytochrome P450 (CYP) 2C19 polymorphism]. Theoretically, the choice and dose of proton pump inhibitor may also influence the suppression of H. pylori infection. The CYP2C19 genotype has recently been found to have an impact on peptic ulcer healing, H. pylori eradication and therapeutic efficacy of proton pump inhibitors.
Methods: Here, we investigated the impact of the CYP2C19 genotype polymorphism and the success of triple therapy (fluoroquinolones/metronidazole/clarithromycin) on antibiotic-resistant strains in eradicating H. pylori in human subjects with non-ulcer dyspepsia (NUD), in human subjects with peptic ulcer disease (PUD) and in asymptomatic human subjects (positive and negative for H. pylori infection).
Results: Based on the CYP2C19 genotypes, determined by Droplet Digital PCR (ddPCR) analysis, we found 11.2%, 62.5% and 26.3% corresponding to rapid metabolizers, intermediate metabolizers and poor metabolizers, respectively. However, we did not find any significant effect for homozygous ABCB1 or CYP2C19*2 and CYP2C19*3 alleles. We detected several participants heterozygous for both ABCB1 and CYP2C19*2, CYP2C19*3 and CYP2C19*17 loci. The participants heterozygous for both ABCB1 and CYP2C19*2 and *3 loci should be defined as intermediate and poor metabolizers according to the haplotype analysis in the NUD, PUD and asymptomatic subjects.
Conclusions: Consequently, fluoroquinolones/metronidazole/clarithromycin-based triple therapies can be used to eradicate H. pylori infection, if one does not know the CYP2C19 genotype of the patient.

Matched MeSH terms: Cytochrome P-450 CYP2C19/genetics*
Fulltext The Role of Genetic Polymorphism and Other Factors on Clopidogrel Resistance (CR) in an Asian Population with Coronary Heart Disease (CHD)

Akkaif MA, Daud NAA, Sha'aban A, Ng ML, Abdul Kader MAS, Noor DAM, et al.

Molecules, 2021 Apr 01;26(7).
PMID: 33915807 DOI: 10.3390/molecules26071987

Clopidogrel is a widely-used antiplatelet drug. It is important for the treatment and prevention of coronary heart disease. Clopidogrel can effectively reduce platelet activity and therefore reduce stent thrombosis. However, some patients still have ischemic events despite taking the clopidogrel due to the alteration in clopidogrel metabolism attributable to various genetic and non-genetic factors. This review aims to summarise the mechanisms and causes of clopidogrel resistance (CR) and potential strategies to overcome it. This review summarised the possible effects of genetic polymorphism on CR among the Asian population, especially CYP2C19 *2 / *3 / *17, where the prevalence rate among Asians was 23.00%, 4.61%, 15.18%, respectively. The review also studied the effects of other factors and appropriate strategies used to overcome CR. Generally, CR among the Asian population was estimated at 17.2-81.6%. Therefore, our overview provides valuable insight into the causes of RC. In conclusion, understanding the prevalence of drug metabolism-related genetic polymorphism, especially CYP2C19 alleles, will enhance clinical understanding of racial differences in drug reactions, contributing to the development of personalised medicine in Asia.

Matched MeSH terms: Cytochrome P-450 CYP2C19/genetics
East Asian perspective on the interaction between proton pump inhibitors and clopidogrel

Zou D, Goh KL

J Gastroenterol Hepatol, 2017 Jun;32(6):1152-1159.
PMID: 28024166 DOI: 10.1111/jgh.13712

Both proton pump inhibitors (PPIs) and clopidogrel are widely prescribed in the Asia-Pacific population. PPIs are the mainstay therapeutic agents for prophylaxis against aspirin gastropathy and for acid-related disorders including gastroesophageal reflux disease. They are also co-prescribed with oral anticoagulant agents and with dual-antiplatelet therapy for the treatment and prevention of gastrointestinal bleeding. Clopidogrel belongs to the drug class of thienopyridines and is currently the most widely prescribed oral anticoagulant agent either alone or in combination with aspirin. Platelet inhibition by clopidogrel is prone to significant inter-individual variability and is believed to be affected by several factors such as genetics and drug-drug interactions. Since it was first reported in 2009, the potential for drug-drug interactions between PPIs and clopidogrel has remained headline news, and its significance in clinical practice is the subject of an ongoing debate. For East Asian patients in particular, the clinical relevance of the interaction between PPIs and clopidogrel remains unclear because of conflicting data, as well as underrepresentation of East Asian subjects in landmark trials. Increased CYP2C19 genetic polymorphisms in individuals from Asia-Pacific countries only fuel the confusion. Recent studies in East Asian cohorts suggests that the potential of PPIs to attenuate the efficacy of clopidogrel could be minimized by the use of newer PPIs with weaker affinity for the CYP2C19 isoenzyme, namely, pantoprazole, dexlansoprazole, and rabeprazole. This review aims to help clinicians choose the most appropriate PPI for co-prescription with clopidogrel in patients from Asia-Pacific countries.

Matched MeSH terms: Cytochrome P-450 CYP2C19/genetics
Pharmacometabolomics analysis of plasma to phenotype clopidogrel high on treatment platelets reactivity in coronary artery disease patients

Amin AM, Sheau Chin L, Teh CH, Mostafa H, Mohamed Noor DA, Abdul Kader MASK, et al.

Eur J Pharm Sci, 2018 May 30;117:351-361.
PMID: 29526765 DOI: 10.1016/j.ejps.2018.03.011

Dual antiplatelet therapy (DAPT) of clopidogrel and aspirin is crucial for coronary artery disease (CAD) patients undergoing percutaneous coronary intervention (PCI). However, some patients may endure clopidogrel high on treatment platelets reactivity (HTPR) which may cause thromboembolic events. Clopidogrel HTPR is multifactorial with some genetic and non-genetic factors contributing to it. We aimed to use nuclear magnetic resonance (1H NMR) pharmacometabolomics analysis of plasma to investigate this multifactorial and identify metabolic phenotypes and pathways associated with clopidogrel HTPR. Blood samples were collected from 71 CAD patients planned for interventional angiographic procedure (IAP) before the administration of clopidogrel 600 mg loading dose (LD) and 6 h after the LD. Platelets function testing was done 6 h post-LD using VerifyNow® P2Y12 assay. Pre-dose and post-dose plasma samples were analysed using 1H NMR. Multivariate statistical analysis was used to indicate the discriminating metabolites. Two metabotypes, each with 34 metabolites (pre-dose and post-dose) were associated with clopidogrel HTPR. Pathway analysis of these metabotypes revealed that aminoacyl-tRNA biosynthesis, nitrogen metabolism and glycine-serine-threonine metabolism are the most perturbed metabolic pathways associated with clopidogrel HTPR. Furthermore, the identified biomarkers indicated that clopidogrel HTPR is multifactorial where the metabolic phenotypes of insulin resistance, type two diabetes mellitus, obesity, gut-microbiota and heart failure are associated with it. Pharmacometabolomics analysis of plasma revealed new insights on the implicated metabolic pathways and the predisposing factors of clopidogrel HTPR.

Matched MeSH terms: Cytochrome P-450 CYP2C19/genetics

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