CYP2C19 Poor Metabolizers Research Articles

Clinical Pharmacogenetics Implementation Consortium Guideline for CYP2C19 Genotype and Clopidogrel Therapy: 2022 Update.

CYP2C19 catalyzes the bioactivation of the antiplatelet prodrug clopidogrel, and CYP2C19 genotype impacts clopidogrel active metabolite formation. CYP2C19 intermediate and poor metabolizers who receive clopidogrel experience reduced platelet inhibition and increased risk for major adverse cardiovascular and cerebrovascular events. This guideline is an update to the 2013 Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline for the use of clopidogrel based on CYP2C19 genotype and includes expanded indications for CYP2C19 genotype-guided antiplatelet therapy, increased strength of recommendation for CYP2C19 intermediate metabolizers, updated CYP2C19 genotype to phenotype translation, and evidence from an expanded literature review (updates at www.cpicpgx.org).

Clopidogrel Use and CYP2C19 Genotypes in Patients Undergoing Vascular Intervention Procedure: A Hospital-Based Study.

PurposeClopidogrel is widely used in coronary artery, peripheral arterial, and cerebrovascular disease. We aimed to study the association of the CYP2C19 phenotype with cardiovascular outcomes and interventional procedures in a hospital-based population.Patients and MethodsThis cross-sectional, retrospective study enrolled patients with prior exposure to clopidogrel at the Taichung Veterans General Hospital (TCVGH) using data extracted from the Taiwan Precision Medicine Initiative (TPMI). Data on the CYP2C19 phenotype, drug-prescription profile, comorbidities, vascular intervention procedures, and hospitalization due to acute myocardial infarction (AMI) or stroke of clopidogrel users were analyzed.ResultsFrom the 32,728 patients in the TCVGH-TPMI cohort, we selected 2687 clopidogrel users. A total of 400 (14.9%) clopidogrel poor metabolizers (PMs), 1235 (46.0%) intermediate metabolizers (IMs), and 1052 (39.2%) extensive metabolizers (EMs) were identified. The predominant loss-of-function allele is *2. In 2687 patients with clopidogrel exposure, the CYP2C19 PM phenotype was unassociated with hospitalization due to AMI or stroke after adjusting for comorbidities and carotid angiographies. Among the 1554 clopidogrel users who underwent cardiovascular intervention, 193 (12.4%) received two or more types of interventional procedures. Compared with non-PMs, patients with the PM phenotype had a higher risk of multiple carotid interventions (OR: 3.13, 95% CI: 1.19–8.22).ConclusionIn this hospital-wide cohort, 8.2% were clopidogrel users, of which 14.9% were CYP2C19 PMs. The result of this study does not support universal genotyping of CYP2C19 in all clopidogrel users to identify risks for stroke and AMI. CYP2C19 PMs are more likely to undergo multiple carotid interventions than non-PMs. Prospective studies to investigate the association of the CYP2C19 genotype and carotid interventions and outcomes are needed to validate our results.

Dutch Pharmacogenetics Working Group (DPWG) guideline for the gene-drug interaction between CYP2C19 and CYP2D6 and SSRIs.

The Dutch Pharmacogenetics Working Group (DPWG) guideline presented here, presents the gene-drug interaction between the genes CYP2C19 and CYP2D6 and antidepressants of the selective serotonin reuptake inhibitor type (SSRIs). Both genes' genotypes are translated into predicted normal metabolizer (NM), intermediate metabolizer (IM), poor metabolizer (PM), or ultra-rapid metabolizer (UM). Evidence-based dose recommendations were obtained, based on a structured analysis of published literature. In CYP2C19 PM patients, escitalopram dose should not exceed 50% of the normal maximum dose. In CYP2C19 IM patients, this is 75% of the normal maximum dose. Escitalopram should be avoided in UM patients. In CYP2C19 PM patients, citalopram dose should not exceed 50% of the normal maximum dose. In CYP2C19 IM patients, this is 70% (65-75%) of the normal maximum dose. In contrast to escitalopram, no action is needed for CYP2C19 UM patients. In CYP2C19 PM patients, sertraline dose should not exceed 37.5% of the normal maximum dose. No action is needed for CYP2C19 IM and UM patients. In CYP2D6 UM patients, paroxetine should be avoided. No action is needed for CYP2D6 PM and IM patients. In addition, no action is needed for the other gene-drug combinations. Clinical effects (increase in adverse events or decrease in efficacy) were lacking for these other gene-drug combinations. DPWG classifies CYP2C19 genotyping before the start of escitalopram, citalopram, and sertraline, and CYP2D6 genotyping before the start of paroxetine as "potentially beneficial" for toxicity/effectivity predictions. This indicates that genotyping prior to treatment can be considered on an individual patient basis.

Analysis of Combined Effect of CYP2C19 Genetic Polymorphism and Proton Pump Inhibitors Coadministration on Trough Concentration of Voriconazole.

PurposeTo analyze the combined effect of CYP2C19 genetic polymorphism and PPIs coadministration on voriconazole trough concentration (VCZ-Ctrough) in Chinese patients with hematological disorders.Patients and MethodsA prospective observational study involved 250 plasma samples from 114 adult patients receiving voriconazole with or without PPIs were analyzed. Demographics and clinical characteristics were obtained from patient’s records. A validated LC-MS/MS was used to quantify the plasma VCZ-Ctrough. Genotyping for CYP2C19*2 and CYP2C19*3 variant alleles was performed by PCR-RFLP followed by DNA sequencing. The combined total score (from 2 to 5) was calculated for each patient. The higher the score, the lesser the metabolism of the patient.FindingsFifty percent of patients administered with voriconazole were coadministered with PPIs, predominantly omeprazole or esomeprazole. Patients exhibiting CYP2C19 poor metabolizer phenotype showed a significantly higher median VCZ-Ctrough, (4.31µg/mL [IQR, 1.64µg/mL–7.36µg/mL]) than patients with normal metabolizer (1.38µg/mL, [IQR, 0.79µg/mL–2.14µg/mL], p < 0.0001). Similarly, patients co-administration with PPIs had higher median VCZ-Ctrough (2.86µg/mL [IQR 1.33µg/mL–4.66µg/mL]), than PPIs non-users (1.71µg/mL, [IQR, 0.86µg/mL–3.48µg/mL], p = 0.001). However, we noted that the median VCZ-Ctrough for each factor was ranging within the normal recommended therapeutic range in the Chinese population (0.5µg/mL–5µg/mL). But when the two factors were combined, the median VCZ-Ctrough was steadily increasing as the metabolic capacity (reflected by combined total score) was increasing. Importantly, the median VCZ-Ctrough in PM/PPIs user (total score 5) was significantly elevated to supra-therapeutic levels compared to NM/PPI non-user group (total score 2) (5.83µg/mL [IQR, 2.19µg/mL–9.51µg/mL] versus 1.13µg/mL [IQR, 0.67µg/mL–1.82µg/mL]), respectively, P < 0.0001. Furthermore, we observed that the elevation of median VCZ-Ctrough to supra-therapeutic levels was largely contributed by omeprazole or esomeprazole compared to lansoprazole or pantoprazole.ConclusionCoadministration with PPIs significantly increased voriconazole trough concentrations and there was an additive effect in CYP2C19 PMs, who were most likely to have supra-therapeutic levels.

Influence of Cytochrome P450 2C19 Genotype on Helicobacter pylori Proton Pump Inhibitor-Amoxicillin-Clarithromycin Eradication Therapy: A Meta-Analysis.

Background: Proton pump inhibitors (PPIs) are the first-line treatment for acid-related diseases. The pharmacokinetics and therapeutic efficacy of PPIs, however, are influenced by genetic factors such as variants in genes encoding drug-metabolizing enzymes (e.g., cytochrome P450 2C19 [CYP2C19]) and drug transporters. We performed a meta-analysis to evaluate the influence of CYP2C19 genotype and PPI class, PPI dose, treatment duration and clarithromycin dose on the cure rate of PPI-containing Helicobacter pylori eradication therapy. Methods: Randomized control trials (RCTs) investigating cure rates using a PPI-amoxicillin-clarithromycin regimen among different CYP2C19 genotypes through May 2021 were included. Results: A total of 25 studies (5,318 patients) were included. The overall eradication rate in the intention-to-treat analysis was 79.0% (3,689/4,669, 95% confidence interval [CI]: 77.8–80.2%), and that in CYP2C19 extensive metabolizers (EMs), intermediate metabolizer (IMs) and poor metabolizers (PMs) was 77.7% (1,137/1,464, 95% CI: 75.3–79.6%), 81.2% (1,498/1,844, 95% CI: 79.3–83.0%) and 86.8% (644/742, 95% CI: 83.9–88.9%), respectively. Meta-analysis showed that the relaTakashitive risk of failed eradication in CYP2C19 EMs compared with IMs and PMs was 1.21 (95% CI: 1.06–1.39, P = 0.006) and 1.57 (95% CI: 1.27–1.94, P < 0.001), respectively, in the fixed-effects model. The cure rate of omeprazole and lansoprazole-containing eradication regimens differed among CYP2C19 genotypes (P < 0.05), while that of rabeprazole and esomeprazole-containing regimens was similar. Conclusion: The cure rates of PPI-amoxicillin-clarithromycin H. pylori eradication regimen, especially those containing omeprazole and lansoprazole, differ among CYP2C19 genotypes. Therefore, selection of a second-generation PPI or tailored treatment may achieve higher eradication rates than first-generation PPI-amoxicillin-clarithromycin triple regimen.

Impact of Automated Best Practice Advisories on Provider Response to CYP2C19 Genotyping Results for Patients on Clopidogrel

Objective The study objective was to examine provider acceptance and genotyping responses to a best practice advisory (BPA) concerning clopidogrel and CYP2C19 intermediate and poor metabolizers within the context of a new pharmacogenomics program at a Midwestern health system. Other secondary objectives analyzed included appropriate BPA firing, the distribution of alleles in study population, indications for clopidogrel use, and impact of indication on therapy change. Methods: In this study, the progress of this program was assessed by quantifying how providers respond to BPAs generated in the electronic medical record (EMR), in the context of a single representative gene–drug–outcome relationship. Patient data was pulled via reports yielding patients with genotyped information in the EMR and cross-referenced with a report evaluating BPA firing occurrences. Results: By capturing antiplatelet therapy changes in response to CYP2C19 genotyping results, 37 patients were found that had 73 BPAs fire. Nine of those patients had alternative antiplatelet therapy ordered. Of these, 6 alternative antiplatelet therapies were ordered from the BPA. Conclusion: Providers utilized BPAs, but responded differently based on individual knowledge of genotypes and indications. Information obtained from this study can be used for provider education and as reference for future design and wording of BPAs.

Association between migraine prevalence, treatment with proton-pump inhibitors and CYP2C19 phenotypes in UK Biobank

Proton-pump inhibitors (PPIs) are used to suppress gastric acid secretion in several gastrointestinal conditions. While these drugs are generally well tolerated, their long-term use may be associated with different adverse effects, including migraine. We analyzed the association between treatment with PPIs (omeprazole, esomeprazole, lansoprazole, pantoprazole and rabeprazole) and migraine prevalence in the UK Biobank cohort through a cross-sectional analysis (using baseline data for 468,280 participants, 16,390 of whom had migraine) and a longitudinal analysis (including 145,007 participants with no migraine at baseline, of whom 3786 had probable migraine without aura [MWOA] and 9981 probable migraine with aura [MWA] or both MWOA and MWA at an average follow-up time of 10.06 years). We also evaluated the modulating role of the metabolizer phenotype of CYP2C19, the major enzyme involved in PPI clearance. Treatment with PPIs was associated with higher migraine prevalence at baseline (odds ratio [OR] = 1.25, p < 0.0001). CYP2C19 rapid metabolizer phenotype was associated with lower prevalence of migraine exclusively in participants treated with PPIs (OR = 0.89, p = 0.029). In addition, treatment with PPIs was associated with higher incidence of both probable MWOA (OR = 1.24, p = 0.002) and MWA (OR = 1.43, p < 0.0001) at follow-up. Treatment with PPIs and CYP2C19 poor metabolizer status were associated with higher incidence of probable chronic migraine exclusively in men. Our results suggest a significant association between treatment with PPIs and migraine in this large population-based cohort and support a potential relevant role of gender and CYP2C19 phenotype.

Influence of CYP2C19 Polymorphisms on the Pharmacokinetics of Omeprazole in Elderly Subjects.

Omeprazole blocks the gastric H+ /K+ adenosine triphosphatase, thus inhibiting gastric acid secretion, and is metabolized by cytochrome P450 (CYP) 2C19. Due to the physiological changes in the elderly, there are different pharmacokinetic consequences compared to young people. The aim of this study was to evaluate the pharmacokinetic profiles of omeprazole in 15 elderly participants according to the CYP2C19 genotype. The concentration-time profiles of omeprazole and its metabolites, 5-hydroxy (5-OH) omeprazole and omeprazole sulfone, were similar between the CYP2C19 extensive metabolizer (EM) and intermediate metabolizer groups. In contrast, when comparing the EM group and CYP2C19 poor metabolizer (PM) group, the EM/PM geometric mean ratio (95% confidence interval) of area under the plasma concentration-time curve from time of dosing to the last measurable concentration was 0.52 (0.27-1.01) and that of the IM group was 0.71 (0.32-1.59), indicating that the exposure of omeprazole in the PM group was increased. The exposure of 5-OH omeprazole was significantly decreased in the PM group when compared to the EM group, with an EM/PM geometric mean ratio (95% confidence interval) of 2.20 (1.50-3.22). In conclusion, the tendency of drug exposure according to the CYP2C19 genotype in the elderly and young adults was similar in that the exposure level was highest in the PM group. However, when compared to young adults, the difference between the genotype groups was smaller in the elderly.

Precision dosing of methadone during pregnancy: A pharmacokinetics virtual clinical trials study

BackgroundMethadone use for the management of opioid dependency during pregnancy is commonplace. Methadone levels are altered during pregnancy due to changes in maternal physiology. Despite this, a paucity of data exist regarding the most appropriate optimal dosing regimens during pregnancy. MethodsThis study applied a pharmacokinetic modeling approach to examine gestational changes in R- and S-methadone concentrations in maternal plasma and fetal (cord) blood. This study did so to derive a theoretical optimal dosing regimen during pregnancy, and to identify the impact of Cytochromes P450 (CYP) 2B6 and 2C19 polymorphisms on methadone maternal and fetal pharmacokinetics. ResultsThe study noted significant decreases in maternal R- and S-methadone plasma concentrations during gestation, with concomitant increases in fetal levels. At a dose of 90 mg once daily, 75% (R-) and 94% (S-) of maternal methadone trough levels were below the lower therapeutic window at term (week 40). The developed optimal dosing regimen escalated doses to 110 mg by week 5, followed by 10 mg increments every 5 weeks up to a maximum of 180 mg once daily near term. This increase resulted in 27% (R-) and 11% (S-) of subjects with trough levels below the lower therapeutic window at term. CYP2B6 poor metabolizers (PM) and either CYP2C19 extensive metabolizers (EM), PM, or ultra-rapid (UM) metabolizer phenotypes demonstrated statistically significant increases in concentrations when compared to their matched CYP2B6 EM counterparts. ConclusionsSpecific and gestation-dependent dose titrations are required during pregnancy to reduce the risks associated with illicit drug use and to maintain fetal safety.

Understanding the Cytochrome P450‐Catalyzed Metabolism of Cannabidiol and the Implications for Hepatotoxicity

Cannabidiol (CBD) is a naturally occurring, non-psychotoxic phytocannabinoid that has gained public attention for its use as an active ingredient in many consumer products and for its recent FDA approval as Epidiolex® (CBD oral solution) in treating seizures associated with Lennox-Gastaut syndrome and Dravet syndrome. Epidiolex® has been associated with dose-dependent hepatotoxicity in clinical trials, and the risk is increased when Epidiolex® is given with valproate, another anti-epileptic drug known to cause liver injury. The mechanism of CBD-related hepatotoxicity, however, remains unknown. CBD is metabolized primarily by cytochrome P450 (CYP) 2C19 and CYP3A4, and by UDP-glucuronosyltransferases (UGTs) to a lesser extent. The goals of this study were to characterize the roles of CYP enzymes in the metabolism of CBD with a focus on generation of the active metabolite 7-hydroxy-CBD (7-OH-CBD) and major inactive metabolite 7-carboxy-CBD (7-COOH-CBD), and to investigate the impact of CYP2C19 genotype on CBD metabolism in human liver microsomes (HLM). We also examined the effect of co-treatment with the nonselective CYP inhibitor 1-aminobenzotriazole and valproate on CBD metabolite generation in sandwich-cultured human hepatocytes (SCHH). Reaction phenotyping experiments using recombinant enzymes and HLM treated with CYP-selective chemical inhibitors indicated that CYP2C19 can sequentially metabolize CBD to 7-OH-CBD and 7-COOH-CBD. Although CYP3A was found to have a significant role in overall CBD clearance and 7-COOH-CBD formation, CYP3A was not involved in 7-OH-CBD generation. In addition, HLM from CYP2C19 poor metabolizers were found to have significantly higher 7-COOH-CBD generation compared to CYP2C19 rapid and ultrarapid metabolizers. In SCHH pre-treated with 1-aminobenzotriazole, formation of hydroxylated CBD metabolites was reduced, while CBD-glucuronide formation increased. Co-treatment with CBD and valproate in SCHH did not significantly alter the metabolic profile of CBD. Further work is needed to determine the mechanisms of CBD-related hepatotoxicity and the interaction between CBD and valproate.

A retrospective analysis of actionable pharmacogenetic/genomic biomarker language in FDA labels

The primary goal of precision medicine is to maximize the benefit‐risk relationships for individual patients by delivering the right drug to the right patients at the right dose. To achieve this goal, it has become increasingly important to assess gene‐drug interactions (GDIs) in clinical settings. The US Food and Drug Administration (FDA) periodically updates the table of pharmacogenetic/genomic (PGx) biomarkers in drug labeling on their website. As described herein, an effort was made to categorize various PGx biomarkers covered by the FDA‐PGx table into certain groups. There were 2 major groups, oncology molecular targets (OMT) and drug‐metabolizing enzymes and transporters (DMETs), which constitute ~70% of all biomarkers (~33% and ~35%, respectively). These biomarkers were further classified whether their labeling languages could be actionable in clinical practice. For OMT biomarkers, ~70% of biomarkers are considered actionable in clinical practice as they are critical for the selection of appropriate drugs to individual patients. In contrast, ~30% of DMET biomarkers are considered actionable for the dose adjustments or alternative therapies in specific populations, such as CYP2C19 and CYP2D6 poor metabolizers. In addition, the GDI results related to some of the other OMT and DMET biomarkers are considered to provide valuable information to clinicians. However, clinical GDI results on the other DMET biomarkers can possibly be used more effectively for dose recommendation. As the labels of some drugs already recommend the precise doses in specific populations, it will be desirable to have clear language for dose recommendation of other (or new) drugs if appropriate.

Impact of genetic variants on clinical outcome after percutaneous coronary intervention in elderly patients.

Elderly patients treated with percutaneous coronary intervention (PCI) have a higher risk of both ischemic and bleeding complications than younger patients. However, few studies have reported how genetic information of elderly patients treated with PCI affects clinical outcomes. We investigated the impact of genetic variants on clinical outcomes in elderly patients. Correlations between single-nucleotide polymorphisms (CYP2C19 and P2Y12 receptor gene G52T polymorphism) and clinical outcomes were analyzed in 811 elderly patients (≥75 years of age) from a prospective multicenter registry. The primary endpoint was a composite of myocardial infarction and death. Secondary endpoints were an individual event of death, cardiac death, myocardial infarction, stent thrombosis, target lesion revascularization, stroke, and major bleeding (Bleeding Academic Research Consortium ≥3). Regarding CYP2C19, patients with poor metabolizers had a significantly higher risk for the primary endpoint (hazard ratio [HR] 2.43; 95% confidence interval [95% CI] 1.12–5.24; p=0.024) and secondary endpoints (death and cardiac death). Regarding P2Y12 G52T, the TT group had a significantly higher occurrence of major bleeding than the other groups (HR 3.87; 95% CI 1.41–10.68; p=0.009). In conclusion, poor metabolizers of CYP2C19 and TT groups of P2Y12 G52T may be significant predictors of poor clinical outcomes in elderly patients.

Pharmacokinetics and Pharmacodynamics of Esomeprazole/Sodium Bicarbonate Immediate-Release Capsules in Healthy Chinese Volunteers: A Cross-Over, Randomized Controlled Trial.

Esomeprazole delayed release tablets (ESO) are one of the most effective treatments for acid-related disorders. The purpose of this study is to compare the safety, pharmacokinetics (PK) and pharmacodynamics (PD) of an immediate-release capsule formulation containing esomeprazole 20mg and sodium bicarbonate 1100mg (IR-ESO) compared to those of the esomeprazole delayed release tablet 20mg (ESO). In addition, the impact of CYP2C19 gene polymorphisms on PK and PD was evaluated. A single-center, open-label, randomized, 2-treatment, 2-sequence, and 2-period crossover study was conducted in 40 healthy Chinese subjects. Subjects received either IR-ESO or ESO for 5days. After single- and multiple-dosing administration, blood samples were collected for PK analysis, and intragastric pH was assessed by 24-h pH monitoring. The CYP2C19 gene polymorphisms were analyzed by Sanger sequencing. The geometric mean ratios (90% confidence interval) [GMR (95%CI)] of IR-ESO/ESO for AUCinf [single dose: 103.60% (96.58%, 111.14%), multiple doses: 101.65% (97.88%, 105.57%)] were within the range of 80.00-125.00%. The AUCinf showed an increasing trend between CYP2C19 extensive metabolizer (EM), intermediate metabolizer (IM), and poor metabolizer (PM) after single-dose and multiple-dose administration (p<0.05). The GMR (95%CI) of IR-ESO/ESO for 24-h integrated gastric acidity from baseline [single dose: 101.07% (96.56%, 105.78%), multiple doses: 101.24% (97.74%, 104.86%)] were within the range of 80.00-125.00%. The percentage changes in 24-h integrated gastric acidity from baseline was significant difference between EM, IM, and PM after single-dose IR-ESO and ESO (p<0.05). Drugs were all well tolerated, and there were no significant differences in adverse events between IR-ESO and ESO. This study showed that IR-ESO can inhibit the secretion of gastric acid rapidly and continuously, and that the PK and PD of IR-ESO are affected by CYP2C19 genotypes. The GMR (95% CI) of IR-ESO/ESO for AUCinf and the percentage changes in 24-h integrated gastric acidity from baseline were all within the range of 80.00-125.00%. Chinese Clinical Trial Registry: ChiCTR1900024935.

Comprehensive analysis of important pharmacogenes in Koreans using the DMET™ platform.

Genetic polymorphisms of enzymes and transporters associated with the absorption, distribution, metabolism, and elimination (ADME) of drugs are one of the major factors that contribute to interindividual variations in drug response. In the present study, we aimed to elucidate the pharmacogenetic profiles of the Korean population using the Affymetrix Drug Metabolizing Enzyme and Transporters (DMET™) platform. A total of 1,012 whole blood samples collected from Korean subjects were genotyped using the DMET™ plus microarray. In total, 1,785 single nucleotide polymorphism (SNP) markers for 231 ADME genes were identified. The genotype and phenotype of 13 clinically important ADME genes implemented in the Clinical Pharmacogenetics Implementation Consortium guidelines were compared among different ethnic groups. Overall, the genotype frequencies of the Korean population were similar to those of the East Asian population. Several genes, notably CYP2C19 and VKORC1, showed marked differences in Koreans compared to Europeans (EURs) or Africans (AFRs). The percentage of CYP2C19 poor metabolizers was 15% in Koreans and less than 3% in EURs or AFRs. The frequencies of causative SNPs of the VKORC1 gene for the low warfarin dose phenotype were 90%, 60%, and 10% in Koreans, EURs and AFRs, respectively. Our findings can be utilized for optimal pharmacotherapy in Korean patients.

Implementation and management outcomes of pharmacogenetic CYP2C19 testing for clopidogrel therapy in clinical practice

PurposeThe antiplatelet prodrug clopidogrel is bioactivated by the polymorphic enzyme CYP2C19. Prospective clinical studies demonstrated an association between CYP2C19 loss of function (LoF) variants and an increased risk of thrombotic events under clopidogrel, but pharmacogenetic (PGx) testing is not frequently implemented in clinical practice. We report our experience with PGx-guided clopidogrel therapy with particular regard to clinically relevant patient management changes.MethodsWe conducted an observational study analyzing patients that underwent PGx testing for clopidogrel therapy at two Swiss hospitals. Primary outcome was the proportion of patients with clinically relevant PGx-based management recommendations and their implementation. The association of recurrent ischemic events under clopidogrel with CYP2C19 LoF variants and other factors was explored in a multivariate case-control analysis.ResultsAmong 56 patients undergoing PGx testing, 18 (32.1%) were classified as CYP2C19 intermediate or poor metabolizers. This resulted in 17 recommendations for a change of antiplatelet therapy, which were implemented in 12 patients (70.1%). In the remaining five patients, specific reasons for non-implementation could be identified. Recurrent ischemic events under clopidogrel were associated with LoF variants (OR 2.2, 95% CI 0.3–14.4) and several cardiovascular risk factors. Associations were not statistically significant in our small study, but plausible and in line with estimates from large prospective studies.ConclusionPGx-guided clopidogrel therapy can identify patients with an elevated risk of ischemic events and offer evidence-based alternative treatments. Successful implementation in clinical practice requires a personalized interdisciplinary service that evaluates indications and additional risk factors, provides specific recommendations, and proactively follows their implementation.

Association of CYP2C19 and CYP2D6 Poor and Intermediate Metabolizer Status With Antidepressant and Antipsychotic Exposure

Precise estimation of the drug metabolism capacity for individual patients is crucial for adequate dose personalization. To quantify the difference in the antipsychotic and antidepressant exposure among patients with genetically associated CYP2C19 and CYP2D6 poor (PM), intermediate (IM), and normal (NM) metabolizers. PubMed, Clinicaltrialsregister.eu, ClinicalTrials.gov, International Clinical Trials Registry Platform, and CENTRAL databases were screened for studies from January 1, 1990, to June 30, 2020, with no language restrictions. Two independent reviewers performed study screening and assessed the following inclusion criteria: (1) appropriate CYP2C19 or CYP2D6 genotyping was performed, (2) genotype-based classification into CYP2C19 or CYP2D6 NM, IM, and PM categories was possible, and (3) 3 patients per metabolizer category were available. The Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines were followed for extracting data and quality, validity, and risk of bias assessments. A fixed-effects model was used for pooling the effect sizes of the included studies. Drug exposure was measured as (1) dose-normalized area under the plasma level (time) curve, (2) dose-normalized steady-state plasma level, or (3) reciprocal apparent total drug clearance. The ratio of means (RoM) was calculated by dividing the mean drug exposure for PM, IM, or pooled PM plus IM categories by the mean drug exposure for the NM category. Based on the data derived from 94 unique studies and 8379 unique individuals, the most profound differences were observed in the patients treated with aripiprazole (CYP2D6 PM plus IM vs NM RoM, 1.48; 95% CI, 1.41-1.57; 12 studies; 1038 patients), haloperidol lactate (CYP2D6 PM vs NM RoM, 1.68; 95% CI, 1.40-2.02; 9 studies; 423 patients), risperidone (CYP2D6 PM plus IM vs NM RoM, 1.36; 95% CI, 1.28-1.44; 23 studies; 1492 patients), escitalopram oxalate (CYP2C19 PM vs NM, RoM, 2.63; 95% CI, 2.40-2.89; 4 studies; 1262 patients), and sertraline hydrochloride (CYP2C19 IM vs NM RoM, 1.38; 95% CI, 1.27-1.51; 3 studies; 917 patients). Exposure differences were also observed for clozapine, quetiapine fumarate, amitriptyline hydrochloride, mirtazapine, nortriptyline hydrochloride, fluoxetine hydrochloride, fluvoxamine maleate, paroxetine hydrochloride, and venlafaxine hydrochloride; however, these differences were marginal, ambiguous, or based on less than 3 independent studies. In this systematic review and meta-analysis, the association between CYP2C19/CYP2D6 genotype and drug levels of several psychiatric drugs was quantified with sufficient precision as to be useful as a scientific foundation for CYP2D6/CYP2C19 genotype-based dosing recommendations.

Association of FMO3 rs1736557 polymorphism with clopidogrel response in Chinese patients with coronary artery disease

Dual antiplatelet therapy with aspirin and clopidogrel is commonly used for coronary artery disease (CAD) patients undergoing percutaneous coronary intervention to prevent stent thrombosis and ischemic events. However, some patients show high on-treatment platelet reactivity (HTPR) during clopidogrel therapy. Genetic factors such as loss-of-function variants of CYP2C19 are validated to increase the risk of HTPR. Flavin-containing monooxygenase 3 (FMO3) is reported to be associated with potency of platelet responsiveness and thrombosis. This study aimed to explore the association between FMO3 rs1736557 polymorphism and clopidogrel response. Five hundred twenty-two Chinese CAD patients treated with dual antiplatelet therapy were recruited from Xiangya Hospital. After oral administration of 300mg loading dose (LD) clopidogrel for 12-24h or 75mg daily maintenance dose (MD) clopidogrel for at least 5days, the platelet reaction index (PRI) was determined by vasodilator-stimulated phosphoprotein-phosphorylation assay. FMO3 rs1736557, CYP2C19*2, and CYP2C19*3 polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Mean PRI value was significantly higher in CYP2C19 poor metabolizers (PMs) and intermediate metabolizers (IMs) than the extensive metabolizers (EMs) (p < 0.001). In addition, FMO3 rs1736557 AA homozygotes showed significantly lower PRI as compared with carriers of the major rs1736557 G allele in the entire cohort and in the MD cohort (p = 0.011, p = 0.008, respectively). The risk of HTPR was decreased significantly in carriers of the rs1736557 A allele (AA vs GG: OR = 0.316, 95% CI: 0.137-0.726, p = 0.005; AA vs GA: OR = 0.249, 95% CI: 0.104-0.597, p = 0.001; AA vs GG+GA: OR = 0.294, 95% CI: 0.129-0.669, p = 0.002), and the association was observed mainly in patients carrying the CYP2C19 LOF allele and in those administered with MD. The FMO3 rs1736557 AA genotype was related to an increased the antiplatelet potency of clopidogrel in Chinese CAD patients. Additional studies are required to verify this finding.

Impact of CYP2C19 and CYP2C9 gene polymorphisms on sodium valproate plasma concentration in patients with epilepsy

BackgroundValproic acid (VPA) is a broad spectrum anticonvulsant drug, which could be partially metabolised by cytochrome P450 (CYP) 2C9 and 2C19 enzymes. This study was designed to investigate the relationship...

Description of Pharmacogenomic Testing Among Patients Admitted to the Intensive Care Unit After Cardiovascular Surgery.

Pharmacogenomic (PGx) testing has the potential to provide information on specific drug-metabolizing enzymes that may lead to an absence, reduction, or increase in medication effect in patients. There is a paucity of prospective studies examining PGx testing in the intensive care unit (ICU) setting. To (1) obtain a PGx panel in a sample of cardiovascular (CV) surgical patients with a planned ICU stay and identify phenotypes, and (2) identify PGx variants that may inform treatment regimens and may warrant prescribing adjustments. Descriptive, single cohort cross-sectional design. Adult (≥18 years) CV patients with an anticipated postoperative ICU stay were enrolled from a large Midwestern tertiary academic medical center. Eligible patients provided informed consent at the time of their CV clinic appointment; PGx testing was then ordered. Pharmacogenomic testing consisted of the Focused Pharmacogenomics panel which included 10 genes and 55 medications. Of the 272 patients screened, 100 (68% male) patients completed PGx testing (mean age 66.2 ± 9.6 years, mean Acute Physiology, Age and Chronic Health Evaluation III score 76.1 ± standard deviation). Pharmacogenomic results were available in the medical record within a median of 52.4 hours (interquartile range: 33.4-80.3). Pharmacogenomic testing results identified 5 CYP2C19 poor metabolizers, 26 CYP2C19 rapid metabolizers, 5 CYP2C19 ultrarapid metabolizers, 6 CYP2D6 poor metabolizers, 5 CYP2D6 poor to intermediate metabolizers, and 2 CYP2D6 rapid metabolizers identified. Overall, 98% of patients had actionable or potentially actionable PGx results, including 82% for warfarin, 65% for propafenone, 65% for tramadol, 46% for oxycodone, 45% for metoprolol, 33% for clopidogrel, 32% for proton pump inhibitors, 25% for statins, and 12% for haloperidol. A significant portion of patients had identified genetic variants that may warrant changes in medication management during and after CV-ICU stay. It remains to be seen if PGx testing leads to improvements in ICU patient outcomes.

Next-Generation Sequencing of CYP2C19 in Stent Thrombosis: Implications for Clopidogrel Pharmacogenomics.

Describe CYP2C19 sequencing results in the largest series of clopidogrel-treated cases with stent thrombosis (ST), the closest clinical phenotype to clopidogrel resistance. Evaluate the impact of CYP2C19 genetic variation detected by next-generation sequencing (NGS) with comprehensive annotation and functional studies. Seventy ST cases on clopidogrel identified from the PLATO trial (n= 58) and Mayo Clinic biorepository (n= 12) were matched 1:1 with controls for age, race, sex, diabetes mellitus, presentation, and stent type. NGS was performed to cover the entire CYP2C19 gene. Assessment of exonic variants involved measuring in vitro protein expression levels. Intronic variants were evaluated for potential splicing motif variations. Poor metabolizers (n= 4) and rare CYP2C19*8, CYP2C19*15, and CYP2C19*11 alleles were identified only in ST cases. CYP2C19*17 heterozygote carriers were observed more frequently in cases (n= 29) than controls (n= 18). Functional studies of CYP2C19 exonic variants (n= 11) revealed 3 cases and only 1 control carrying a deleterious variant as determined by in vitro protein expression studies. Greater intronic variation unique to ST cases (n= 169) compared with controls (n= 84) was observed with predictions revealing 13 allele candidates that may lead to a potential disruption of splicing and a loss-of-function effect of CYP2C19 in ST cases. NGS detected CYP2C19 poor metabolizers and paradoxically greater number of so-called rapid metabolizers in ST cases. Rare deleterious exonic variation occurs in 4%, and potentially disruptive intronic alleles occur in 16% of ST cases. Additional studies are required to evaluate the role of these variants in platelet aggregation and clopidogrel metabolism.