Intermediate Metabolizers Research Articles

Effect of metoprolol exposure following myocardial infarction on future cardiovascular events: a Mendelian randomization study.

The clinical benefit of up-titration of metoprolol to a guideline-recommended target dose after myocardial infarction (MI) is unknown. Our aim was to investigate whether variation in metoprolol exposure determined by cytochrome p450 enzyme 2D6 (CYP2D6) influences the occurrence of major adverse cardiovascular events (MACE) and cardiovascular death (CV death) among patients treated with metoprolol after MI. This Mendelian randomization study was performed using individual-level data from 1554 patients treated with metoprolol after an acute MI. CYPD26 genotype was applied as a binary genetic instrument assigning patients into two metoprolol exposure groups: CYP2D6 normal metabolizers (NM) (low exposure) and CYP2D6 intermediate and poor metabolizers (IM + PM) (high exposure). The null hypothesis of no association between the CYP2D6 metabolizer subgroup and MACE or CV death was tested using the Cox proportional hazards model. All-cause mortality and individual components of MACE were included as secondary outcomes. In total, 879 (56.6%) patients were classified as NM and 675 (43.4%) as IM + PM. During the 3-year follow-up, 56 patients (6.4%) in the NM group had an outcome of MACE, and 24 (2.7%) patients died from CV disease. Corresponding frequency in the IM + PM group was 47 (7.0%) and 22 (3.3%), respectively. There was no association between genotype and MACE [unadjusted HR 1.12 (CI 0.76, 1.65)] or CV death [unadjusted HR 1.20 (CI 0.67, 2.14)], or between the CYP2D6 group and any of the secondary outcomes. In patients treated with metoprolol after MI, variation in metoprolol exposure determined by CYP2D6 did not impact the occurrence of cardiovascular events.

Role of CYP2D6 polymorphisms in tramadol metabolism in a context of co-medications and overweight.

Very few quantitative data exist on tramadol metabolites, which hampers our understanding of their role in efficacy and safety of tramadol. We aimed to provide quantitative data on tramadol and its 5 main metabolites in a patient cohort and to determine whether metabolite ratios can be predictive of a CYP2D6 metabolism phenotype. We also aimed to investigate the influence of co-medications and patient profile (BMI, glycemia, lipid levels) on tramadol metabolite ratios. Overall, 37 patient samples from the CONSTANCES cohort contained tramadol and its 5 metabolites. Mean concentrations found tramadol at 343.2±223.2μg/L, M1 at 62.4±41.4μg/L, M2 at 210.0±272.3, M3 at 1.76±3.0μg/L, M4 at 1.8±2.8μg/L and M5 at 31.8±28.4μg/L. The most frequent CYP2D6 phenotype was extensive metabolizers (51.3%), followed by intermediate metabolizers (24.3%) and poor metabolizers (10.8%). CYP2D6-inhibiting co-medications impacted tramadol metabolism independently of CYP2D6 metabolism phenotype. Lipid parameters and glycemia were significantly associated with changes in tramadol metabolic ratios. Metabolic ratios are not sufficient to determine the CYP2D6 metabolic phenotype in patients. CYP2D6 inhibitors and obesity/NAFLD/diabetes impact tramadol metabolism. These factors are likely to impact the analgesic efficacy and safety profile of tramadol, justifying the need for further studies in this area.

CYP2D6 genotype and associated 5-HT3 receptor antagonist outcomes: A systematic review and meta-analysis.

5-hydroxytryptamine-3 (5-HT3) receptor antagonists including ondansetron, tropisetron, dolasetron, palonosetron, granisetron, and ramosetron are commonly used to prevent and treat nausea and vomiting. Most of these medications are at least partially metabolized via the highly polymorphic CYP2D6 enzyme, resulting in variations of metabolism among individuals. Current (2017) international prescribing guidelines for ondansetron/tropisetron use according to genotype provide recommendations for CYP2D6 ultrarapid metabolizers but not intermediate or poor metabolizers. However, multiple studies have been conducted since this guideline was published. This review evaluated all available evidence of an association between CYP2D6 genotype and 5-HT3 receptor antagonist outcomes, including in patients who are CYP2D6 intermediate/poor metabolizers and pediatric-specific studies. In this review, we confirm that CYP2D6 genotype impacts ondansetron response in a postoperative nausea and vomiting setting, which was supported by a meta-analysis. We also highlight the heterogeneity and limitations of included studies as well as provide future directions for pharmacogenomics research.

Integrating pharmacogenetic testing in the management of gastrointestinal cancers.

113 Background: Gastrointestinal cancers are among the most prevalent malignancies, often treated with chemotherapeutic agents whose efficacy and toxicity can be influenced by genetic variations. Pharmacogenetic testing for key metabolic genes, including DPYD, UGT1A1, and G6PD, can guide personalized treatment approaches. Methods: We analyzed samples from 3,519 individuals for genotyping using semiconductor-based Next-Generation Sequencing (NGS) technology. High-quality genomic DNA was extracted and subjected to target enrichment via high multiplex PCR amplification using an NGS panel targeting variants of key metabolic genes, including DPYD, G6PD, and UGT1A1. Results: For the DPYD gene, 96% of patients were normal metabolizers. However, 4% intermediate and 0.17% individuals had poor metabolizer status. Poor metabolizers possess homozygous non-functional alleles, leading to complete dihydropyrimidine dehydrogenase (DPD) deficiency and increased toxicity risk with fluoropyrimidine drugs like 5-fluorouracil (5-FU), Capecitabine, and Tegafur. Patients with certain homozygous or compound heterozygous variants in the DPYD gene are at increased risk for acute early-onset toxicity and serious, including fatal, adverse reactions due to fluorouracil. 5-FU is not recommended for use in patients known to have certain homozygous or compound heterozygous DPYD variants that result in complete absence of DPD activity. Intermediate metabolizers exhibit approximately 50% reduced DPD activity, necessitating a 50% reduction in starting doses followed by careful titration based on toxicity. UGT1A1 analysis revealed 46% normal, 42% intermediate, and 12% poor metabolizers, affecting Irinotecan metabolism and toxicity risks. Poor metabolizers show decreased UGT1A1 activity, resulting in reduced clearance of Irinotecan and increased risk of dose-limiting toxicities. These patients are also at higher risk for neutropenia, diarrhea, and asthenia, requiring starting dose adjustments. Additionally, they may experience elevated hyperbilirubinemia with treatments like Regorafenib. Recognizing G6PD deficiency in GI cancers can prevent serious complications and ensure safer treatment options. G6PD testing indicated that 98% were homozygous wildtype, 2% heterozygous, and 0.31% homozygous/hemizygous deficient. Patients with homozygous/hemizygous deficient genotype may be at increased risk for drug-induced hemolysis, particularly when treated with Dabrafenib. Conclusions: These findings highlight the therapeutic significance of incorporating genetic testing into clinical practice to tailor treatments, enhance drug efficacy, and minimize side effects in GI cancer management. By integrating pharmacogenetic insights, the safety and effectiveness of therapies can be significantly improved, ultimately leading to better patient care in GI oncology.

Laying the groundwork: Exploring pesticide exposure and genetic factors in south-eastern Brazilian farmers.

Brazil is the world leader in pesticide consumption, and its indiscriminate use puts farmers' health at risk. The CYP2C9 gene encodes the CYP2C9 enzyme, which metabolizes several endogenous substrates and specific xenobiotics, especially pesticides. Our goal is to study the risk of pesticide use, especially the herbicide glyphosate, in the development of diseases and the association with two CYP2C9 polymorphisms, in farmers living in the southern region of Espírito Santo state, Brazil. The allelic frequency of CYP2C9*1, CYP2C9*2 and CYP2C9*3 was determined in blood samples from individuals exposed or not to pesticides using real-time PCR. 304 blood samples were analyzed, dividing CYP2C9 genotypes into three metabolization classes: normal, intermediate, and slow. Our results indicate that normal metabolizers may be more susceptible to conditions such as high blood pressure, cardiovascular disease, and kidney problems. Intermediate metabolizers show an association with attention deficit disorder and miscarriages, suggesting that farmers' symptoms correlated with their CYP2C9 genotype. Insufficient data prevented conclusions about slow metabolizers (*2 and/or *3). These findings suggest that the CYP2C9 genotype may influence the way farmers exposed to pesticides respond, but more research is needed to clarify causality and investigate other possible health effects. As an introductory effort, this study provides insights into the complex relationship between genetic variations and pesticide exposure, laying the groundwork for future research. This pioneering work on associations between specific genetic variations and health risks with pesticide exposure, emphasizes the importance of personalized medicine and stricter regulation of pesticide use for public health and occupational safety.

Distribution of CYP2D6 multiplication, CYP2D6*5, and clinical implications in postoperative patients receiving tramadol analgesia in the Minangkabau ethnic group, Indonesia

Background Cytochrome P450 2D6 (CYP2D6) is an important enzyme that metabolizes commonly used drugs, such as tramadol hydrochloride (a widely used opioid analgesic). Genetic polymorphisms of CYP2D6 have been shown to influence the pharmacodynamic properties of administered drugs. This study aimed to screen 63 postoperative patients (wild-type, CYP2D6*5, and CYP2D6 multiplication) of Minangkabau ethnicity in West Sumatera, Indonesia, who received tramadol using a modified long PCR method, and to investigate the clinical impact of tramadol on these patients. This study had a retrospective clinical trial registry number NCT06642480. Methods The Reported Long PCR was modified using different DNA polymerases, optimizing annealing, and the number of step PCR to detect wild-type, CYP2D6*5, and multiplication CYP2D6. To ensure accurate PCR, the size of the PCR product was monitored: wild-type (5kb), CYP2D6*5 (6kb), and CYP2D6 multiplication genotype (10 kb). The wild-type PCR product was used as the internal control. The method was applied to screen 63 postoperative patients of Minangkabau ethnicity who received tramadol. The clinical impact was investigated and analyzed using analysis of variance (ANOVA) followed by a chi-square test. Result The Long PCR was successfully modified with a two-step PCR at 68°C °C as the annealing and extension temperatures. The screened genotype patients were dominated by the wild-type, followed by CYP2D6*5, and multiplication CYP2D6 with percentages of 89%, 6,3%, and 4,7% respectively. A total of 6.3% of CYP2D6*5 cases were classified as heterozygous and predicted as intermediate metabolizers. In addition, sex and age did not affect postoperative tramadol analgesia treatment, whereas weight had a significant impact (p=0.008). Conclusion The percentages of CYP2D6*5 and CYP2D6 multiplication genotypes were similar to those observed in another Asian population. Based on statistical analysis, tramadol was effective as an analgesic treatment for postoperative Minangkabau ethnicity patients with wild-type, CYP2D6*5, and multiple CYP2D6 genotypes. Further studies with larger sample sizes and longer follow-up periods are required to confirm these findings.

Pharmacogenomic profiling of the South Korean population: Insights and implications for personalized medicine.

Adverse drug reactions (ADRs) pose substantial public health issues, necessitating population-specific characterization due to variations in pharmacogenes. This study delineates the pharmacogenomic (PGx) landscape of the South Korean (SKR) population, focusing on 21 core pharmacogenes. Whole genome sequencing (WGS) was conducted on 396 individuals, including 99 healthy volunteers, 95 patients with chronic diseases, 81 with colon cancer, 81 with breast cancer, and 40 with gastric cancer, to identify genotype-specific drug dosing recommendations. Our detailed analysis, utilizing high-throughput genotyping (HTG) of CYP2D6 and comparative data from the 1,000 Genomes Project (1KG) and the US National Marrow Donor Program (NMDP), revealed significant pharmacogenetic diversity in core pharmacogenes such as CYP2B6, CYP2C19, CYP4F2, NUDT15, and CYP2D6. Notably, intermediate metabolizer frequencies for CYP2B6 in SKR (3.28%) were comparable to Europeans (5.77%) and East Asians (5.36%) but significantly differed from other global populations (p < 0.01). For CYP2C19, 48.74% of SKR individuals were classified as intermediate metabolizers, with the *35 allele (2.02%) being unique to SKR, the allele not observed in other East Asian populations. Additionally, the high-risk *3 allele in CYP4F2 was significantly more frequent in SKR (34.72%) than in other East Asian populations (p < 0.01). NUDT15 poor metabolizers were found in 0.76% of SKR, aligning closely with other East Asians (1.59%), while TPMT poor metabolizers were predominantly observed in Europeans and Africans, with one case in SKR. We identified significant allele frequency differences in CYP2D6 variants rs1065852 and rs1135840. Among the 72 drugs analyzed, 93.43% (n = 370) of patients required dosage adjustments for at least one drug, with an average of 4.5 drugs per patient. Moreover, 31.31% (n = 124) required adjustments for more than five drugs. These findings reveal the substantial pharmacogenetic diversity of the SKR population within the global population, emphasizing the urgency of integrating population-specific PGx data into clinical practice to ensure safe and effective drug therapies. This comprehensive PGx profiling in SKR not only advances personalized medicine but also holds the potential to significantly improve healthcare outcomes on a broader scale.

Pharmacogenetic-guided dosing for fluoropyrimidine (DPYD) and irinotecan (UGT1A1*28) chemotherapies for patients with cancer (PACIFIC-PGx): A multicenter clinical trial.

PACIFIC-PGx evaluated the feasibility of implementing pharmacogenetics (PGx) screening in Australia and the impact of DPYD/UGT1A1 genotype-guided dosing on severe fluoropyrimidine (FP) and irinotecan-related toxicities and hospitalizations, compared to historical controls. This prospective single arm trial enrolled patients starting FP/irinotecan for any cancer between 7 January 2021 and 25 February 2022 from four Australian hospitals (one metropolitan, three regional). During the accrual period, 462/487 (95%) consecutive patients screened for eligibility for DPYD and 50/109 (46%) for UGT1A1 were enrolled and genotyped (feasibility analysis), with 276/462 (60%) for DPYD and 30/50 (60%) for UGT1A1 received FP/irinotecan (safety analysis). DPYD genotyping identified 96% (n = 443/462) Wild-Type, 4% (n = 19/462) Intermediate Metabolizers (50% dose reduction), and 0% Poor Metabolizers. UGT1A1 genotyping identified 52% (n = 26/50) Wild-Type, 40% (n = 20/50) heterozygous, and 8% (n = 4/50) homozygous (30% dose reduction). Key demographics for the FP/irinotecan safety cohorts included: age range 23-89/34-74 years, male 56%/73%, Caucasian 83%/73%, lower gastrointestinal cancer 50%/57%. Genotype results were reported prior to cycle-1 (96%), average 5-7 days from sample collection. PGx-dosing for DPYD variant allele carriers reduced high-grade toxicities compared to historic controls (7% vs. 39%; OR = 0.11, 95% CI 0.01-0.97, p = 0.024). High-grade toxicities among Wild-Type were similar (14% vs. 14%; OR = 0.99, 95% CI 0.64-1.54, p = 0.490). PGx-dosing reduced FP-related hospitalizations (-22%) and deaths (-3.7%) compared to controls. There were no high-grade toxicities or hospitalizations for UGT1A1*28 homozygotes. PGx screening and prescribing were feasible in routine oncology care and improved patient outcomes. Findings may inform expanded PGx programs within cancer and other disease settings.

Determining Targets for Antiretroviral Drug Concentrations: A Causal Framework Illustrated With Pediatric Efavirenz Data From the CHAPAS-3 Trial.

Determining a therapeutic window for maintaining antiretroviral drug concentrations within an appropriate range is required for identifying effective dosing regimens. The limits of this window are typically calculated using predictive models. We propose that target concentrations should instead be calculated based on counterfactual probabilities of relevant outcomes and describe a counterfactual framework for this. The proposed framework is applied in an analysis including longitudinal observational data from 125 HIV-positive children treated with efavirenz-based regimens within the CHAPAS-3 trial, which enrolled children < 13 years in Zambia/Uganda. A directed acyclic graph was developed to visualize the mechanisms affecting antiretroviral concentrations. Causal concentration-response curves, adjusted for measured time-varying confounding of weight and adherence, are calculated using g-computation. The estimated curves show that higher concentrations during follow-up, 12/24 h after dose, lead to lower probabilities of viral failure (> 100 c/mL) at 96 weeks of follow-up. Estimated counterfactual failure probabilities under the current target range of 1-4 mg/L range from 24% to about 2%. The curves are almost identical for slow, intermediate and extensive metabolizers and show that a mid-dose concentration level of ≥ 3.5 mg/L would be required to achieve a failure probability of < 5%. Our analyses demonstrate that a causal approach may lead to different minimum concentration limits than analyses that are based on purely predictive models. Moreover, the approach highlights that indirect causes of failure, such as patients' metabolizing status, may predict patients' failure risk, but do not alter the threshold at which antiviral activity of efavirenz is severely reduced.

Human Cytochrome P450 Cancer-Related Metabolic Activities and Gene Polymorphisms: A Review.

Cytochromes P450 (CYPs) are heme-containing oxidoreductase enzymes with mono-oxygenase activity. Human CYPs catalyze the oxidation of a great variety of chemicals, including xenobiotics, steroid hormones, vitamins, bile acids, procarcinogens, and drugs. In our review article, we discuss recent data evidencing that the same CYP isoform can be involved in both bioactivation and detoxification reactions and convert the same substrate to different products. Conversely, different CYP isoforms can convert the same substrate, xenobiotic or procarcinogen, into either a more or less toxic product. These phenomena depend on the type of catalyzed reaction, substrate, tissue type, and biological species. Since the CYPs involved in bioactivation (CYP3A4, CYP1A1, CYP2D6, and CYP2C8) are primarily expressed in the liver, their metabolites can induce hepatotoxicity and hepatocarcinogenesis. Additionally, we discuss the role of drugs as CYP substrates, inducers, and inhibitors as well as the implication of nuclear receptors, efflux transporters, and drug-drug interactions in anticancer drug resistance. We highlight the molecular mechanisms underlying the development of hormone-sensitive cancers, including breast, ovarian, endometrial, and prostate cancers. Key players in these mechanisms are the 2,3- and 3,4-catechols of estrogens, which are formed by CYP1A1, CYP1A2, and CYP1B1. The catechols can also produce quinones, leading to the formation of toxic protein and DNA adducts that contribute to cancer progression. However, 2-hydroxy- and 4-hydroxy-estrogens and their O-methylated derivatives along with conjugated metabolites play cancer-protective roles. CYP17A1 and CYP11A1, which are involved in the biosynthesis of testosterone precursors, contribute to prostate cancer, whereas conversion of testosterone to 5α-dihydrotestosterone as well as sustained activation and mutation of the androgen receptor are implicated in metastatic castration-resistant prostate cancer (CRPC). CYP enzymatic activities are influenced by CYP gene polymorphisms, although a significant portion of them have no effects. However, CYP polymorphisms can determine poor, intermediate, rapid, and ultrarapid metabolizer genotypes, which can affect cancer and drug susceptibility. Despite limited statistically significant data, associations between CYP polymorphisms and cancer risk, tumor size, and metastatic status among various populations have been demonstrated. The metabolic diversity and dual character of biological effects of CYPs underlie their implications in, preliminarily, hormone-sensitive cancers. Variations in CYP activities and CYP gene polymorphisms are implicated in the interindividual variability in cancer and drug susceptibility. The development of CYP inhibitors provides options for personalized anticancer therapy.

Pharmacogenotyping disproves genetic cause of drug-related problems in family history: a case report

BackgroundIn clinical practice, family medication history is not routinely assessed as part of a patient’s family health history (FHH). The information is self-reported and can depend on the individual’s subjective perception. To illustrate how pharmacogenetic (PGx) testing results could be used to validate self-reported family medication history on drug-related problems (DRP), as well as to inform medication-related decisions, we herein present a case involving ten members of the same family.Case PresentationPrior to a planned surgery, a preemptive PGx panel test was performed for a nine-year-old girl due to self-reported family medication history. The PGx panel test was also performed for her three siblings, parents, and grandparents. The focus was directed to the paternal grandmother, as she reported DRP from the hypnotic agent propofol, and to the maternal grandmother, as she described DRP after the administration of codeine and tramadol. A commercial PGx panel test of 100 variations in 30 different genes was conducted and analyzed focusing on genetic variants in cytochrome P450 enzyme 2B6 (CYP2B6), and CYP2D6 as they are involved in the biotransformation of propofol and the bioactivation of codeine and tramadol, respectively. The girl was identified as (1) CYP2B6 intermediate metabolizer (IM) with reduced enzyme activity and (2) CYP2D6 poor metabolizer (PM) with no enzyme activity. Regarding the planned surgery, it was recommended (1) to carefully titrate propofol dosage with increased monitoring of potential DRP and (2) to avoid opioids whose activation is mediated by CYP2D6 (e.g. codeine and tramadol). Further PGx testing revealed (1) the paternal grandmother as CYP2B6 normal metabolizer (NM) and (2) the maternal grandmother as CYP2D6 NM.ConclusionThe original trigger for PGx testing was the self-reported, conspicuous family medication history of DRP reported by the grandmothers. However, the girl’s genotype predicted phenotypes of CYP2B6 IM and CYP2D6 PM, differed from the grandmothers’. With this exemplary case, we propose that hereditary concerns based on self-reported information on DRP should be verified by a PGx panel test, when the respective drug exhibits a PGx association. Also, the girl’s PGx testing results provided important medication recommendations, which were considered perioperatively by the anesthetist suggesting to use PGx testing results preemptively to inform medication-related decisions.

CYP2D6 Phenotype and Breast Cancer Outcomes: A Bias Analysis and Meta-Analysis.

We evaluated the impact of systematic bias due to loss of heterozygosity (LOH) and incomplete phenotyping in studies examining the relationship between CYP2D6 variants and breast cancer recurrence among women treated with tamoxifen. We performed a systematic review of the literature on tamoxifen, CYP2D6 variants, and breast cancer recurrence. A quantitative bias analysis was performed to adjust for LOH and incomplete phenotyping. Bias-adjusted results were then combined in a meta-analysis. Thirty-three studies informed the bias analysis and meta-analysis on CYP2D6 variants and breast cancer recurrence and/or mortality. An unadjusted meta-analysis suggested increased risk of recurrence and/or mortality for poor relative to normal metabolizers [RR = 1.28; 95% simulation interval (SI), 1.04-1.58] with substantial heterogeneity (I2 = 27%; P for heterogeneity = 0.07). Adjusting for LOH and incomplete genotyping resulted in a slight change in the effect estimate and a decrease in heterogeneity (RR = 1.34; 95% SI, 1.10-1.63; I2 = 0%; P for heterogeneity = 0.17). Intermediate metabolizers had a slightly increased risk of recurrence and/or mortality relative to normal metabolizers (RR = 1.15; 95% SI, 1.00-1.34; I2 = 0%; P for heterogeneity = 0.89). Adjusting for biases such as LOH and incomplete genotyping reduced observed heterogeneity between studies. Individuals with poor CYP2D6 phenotypes were at increased risk for breast cancer outcomes compared with those with normal phenotypes. Reduction in CYP2D6 activity was associated with an increased risk of breast cancer recurrence and/or mortality, and results underscore the importance of quantitatively adjusting for biases when aggregating study results.

The impact of CYP2D6 on donepezil concentration and its lack of effect on the treatment response and adverse effect in Korean patients with Alzheimer's disease.

Donepezil, an acetylcholinesterase inhibitor, is widely used for managing the symptoms of Alzheimer's disease (AD), yet its clinical response varies widely among individuals. This study aims to investigate the influence of CYP2D6 genetic variants on donepezil concentration, treatment response, and adverse effects in Korean patients with AD dementia. We conducted a longitudinal study involving 76 patients receiving either 5 mg or 10 mg of donepezil. Genetic testing identified 9 CYP2D6 alleles, categorizing patients by metabolizing abilities. Blood sampling for plasma concentrations of donepezil were performed at steady-state. Mini-Mental State Examination (MMSE) were conducted at 12, 24 and 36 months after the initiation of treatment. Adverse events were collected throughout the study period. Donepezil plasma concentrations differed significantly among metabolizer statuses (mean 56.8 ± 27.1 ng/ml in normal metabolizers vs. 69.6 ± 30.1 ng/ml in intermediate metabolizers, p = 0.042), but these differences did not affect cognitive function over three years as assessed by MMSE. Additionally, there was no significant correlation between donepezil plasma concentration and adverse events. Our study is the first to elucidate the associations between CYP2D6 genotype and the concentration, clinical response or adverse events of donepezil in Korean patients with AD dementia. Larger studies are necessary to fully understand the impact of CYP2D6 genetic variants on therapeutic outcomes with donepezil.

CYP2C19 Loss-of-Function is an Associated Risk Factor for Premature Coronary Artery Disease: A Case-Control Study.

Cytochrome P450 2C19 (CYP2C19) is a major enzyme involved in the biotransformation and metabolism of various substances. Loss-of-function of the CYP2C19 gene represents downregulation of CYP2C19 enzyme indication limited or no enzymatic function, which may be, in turn, associated with some disease susceptibility. The relationship between CYP2C19 polymorphisms and susceptibility to premature coronary artery disease (PCAD) is not fully understood. This study aimed to assess this relationship. This study included 635 PCAD patients, and 548 age-matched non-CAD individuals as controls, from November 2019 to August 2023. The CYP2C19 rs4244285 (681G > A, *2) and rs4986893 (636G > A, *3) were genotyped, and the distribution of CYP2C19 polymorphisms between patients and controls and the relationship between CYP2C19 polymorphisms and PCAD risk were analyzed. A total of 442 (37.4%), 543 (45.9%), and 198 (16.7%) individuals had CYP2C19 extensive metabolizer (EM) (*1/*1), intermediate metabolizer (IM) (*1/*2 and *1/*3), and poor metabolizer (PM) (*2/*2, *2/*3, and *3/*3) phenotypes, respectively. CYP2C19 *2/*2 genotype frequency was higher, *1/*1 genotype was lower in PCAD patients than controls. Individuals with CYP2C19 PM phenotype had higher triglyceride (TG) levels than those with CYP2C19 EM or IM phenotypes. Logistic regression analysis showed that body mass index (BMI) ≥24.0 kg/m2 (≥24.0 kg/m2 vs 18.5-23.9 kg/m2, odds ratio (OR): 1.326, 95% confidence interval (CI): 1.041-1.688, p = 0.022), smoking (OR: 1.974, 95% CI: 1.283-3.306, p = 0.002), hypertension (OR: 1.327, 95% CI: 1.044-1.687, p = 0.021), diabetes mellitus (OR: 1.390, 95% CI: 1.054-1.834, p = 0.020), CYP2C19 PM phenotype (PM phenotype vs EM phenotype, OR: 1.701, 95% CI: 1.200-2.411, p = 0.003), and CYP2C19 IM+PM phenotypes (IM+PM vs EM phenotype, OR: 1.369, 95% CI: 1.077-1.740, p = 0.010) were associated with PCAD. CYP2C19 PM or IM+PM phenotypes, overweight, smoking, hypertension, and diabetes mellitus were associated with PCAD.

CYP2C19 loss-of-function variants are independent risk factors for premature cerebral infarction: a hospital based retrospective study

ObjectiveCytochrome P450 2C19 (CYP2C19) plays an vital role in the course of cardiovascular and cerebrovascular diseases by affecting lipid metabolism. Triglyceride-glucose (TyG) is a comprehensive index composed of triglyceride and blood glucose, has relationship with some diseases. There was no research report on the association CYP2C19 polymorphisms, TyG with premature cerebral infarction (CI) (onset ≤ 65 years old) susceptibility.MethodsThis study retrospectively analyzed 1953 CI patients aged ≤ 65 years old from December 2018 to March 2024, and 1919 age-matched individuals with non-CI as controls. The relationship between CYP2C19 polymorphisms, TyG and premature CI risk were analyzed.ResultsThe proportion of hypertension, and diabetes mellitus in patients with premature CI was higher than those in controls. The serum total cholesterol (TC), triglycerides (TG), low-density lipoprotein-cholesterol (LDL-C), and TyG levels in patients with premature CI were significantly higher than those in controls (all p < 0.05). The patients had lower CYP2C19 *1 allele frequency (63.3% vs. 69.6%, p < 0.001) and higher CYP2C19 *2 allele frequency (31.3% vs. 25.4%, p < 0.001) than controls. Logistic regression analysis showed that smoking history (odds ratio (OR): 1.193, 95% confidence interval (CI): 1.002–1.422, p = 0.048), hypertension (OR: 3.371, 95% CI: 2.914–3.898, p < 0.001), diabetes mellitus (OR: 1.911, 95% CI: 1.632–2.237, p < 0.001), CYP2C19 intermediate metabolizer (IM) + poor metabolizer (PM) phenotypes (OR: 1.424, 95% CI: 1.243–1.631, p < 0.001), and dyslipidemia (OR: 1.294, 95% CI: 1.077–1.554, p = 0.006) were independent risk factors for premature CI.ConclusionsHistory of smoking, hypertension, diabetes mellitus, dyslipidemia, and CYP2C19 IM + PM phenotypes were independently associated with premature CI susceptibility.

Do CYP2D6 polymorphisms affect the efficacy and toxicity of flecainide? A cohort study

Abstract Background The CYP2D6 enzyme, coded by the CYP2D6 gene, is the primary metabolic pathway for flecainide.(1,2) Over the years, studies on how different variants of this gene affect flecainide metabolism and efficacy have yielded contradictory results.(3–7) This is likely due to the fact that CYP2D6 pharmacogenetic classifications were not standardized until 2017.(8,9) Purpose To date, there has been no published study using a standardized classification to assess the efficacy and toxicity of flecainide across different CYP2D6 phenotypes; therefore, we decided to study this. Methods We conducted a cohort study with data collected through indirect methods, blinding all parties involved except the statistician. We identified patients with flecainide prescriptions (100 mg/12 h) and follow-up in our health area (n=450,136 people) between 2017 and 2021. A primary combined endpoint composed of initial inefficacy and early toxicity was pre-set, and a secondary combined endpoint of toxicity or inefficacy during follow-up. Results 104 patients met the criteria and agreed to participate: 38 (36.5%) intermediate metabolizers, 52 (50%) normal metabolizers, 2 (1.9%) could not be classified with certainty (compatible with intermediate or normal metabolizers), 7 (6.7%) poor metabolizers, 4 (3.8%) ultra-rapid metabolizers, and 1 (1%) possible hybrid. Intermediate and normal metabolizers showed an almost superimposable incidence of the primary endpoint (28,9% vs 28,8%, p=0.99), early inefficacy (21,6% vs 17,4%, p=0.97) and early toxicity (13,2% vs 13,3%, p=0.72). No significant differences were observed in multivariate analysis (p=0.76, picture 1) or in a combined endpoint of toxicity or inefficacy during follow-up (p=0.58, Kaplan-Meier in picture 2). Differences were seen in the primary endpoint when comparing poor metabolizers to the rest of the sample, although they did not reach statistical significance (p=0.07), likely due to the small number of patients in this group (n=7, absolute risk reduction -32%; 95% confidence interval: -41% to -23%). Conclusions Using the standardized classification for CYP2D6 pharmacogenetics, no statistically significant differences were detected between the two largest groups, intermediate and normal metabolizers. It is possible that better results are achieved in poor metabolizers. Based on these results, it is worth questioning whether, in an attempt to minimize the risk of flecainide toxicity, doses that are subtherapeutic in all groups except slow metabolizers have been used unknowingly.

Effect of CYP3A5*3 genotype on exposure and efficacy of quetiapine: A retrospective, cohort study

BackgroundThe involvement of cytochrome P450 3A5 (CYP3A5) in the metabolism of quetiapine has been proposed, though conclusive evidence is lacking. This study aimed to quantitatively assess the impact of CYP3A5 genetic variability on quetiapine exposure in a Chinese patient population. MethodsPatient data were retrospectively collected from the database of the Mental Health Centre at the First Hospital of Hebei Medical University, covering the period from September 1, 2019, to July 1, 2023. The study included patients genotyped for CYP3A5 who were treated with quetiapine. Inclusion criteria for the analysis of pharmacokinetic parameters, such as serum concentrations of the drug and its metabolites, included oral administration of quetiapine, availability of information on the prescribed daily dose and concomitant medications, and the determination of steady-state blood levels at the time of sampling (after at least 3 days of continuous administration at the same dose). Exclusion criteria comprised polypharmacy with known CYP3A4 inducers or inhibitors, as well as patients with hepatic or renal insufficiency. The primary endpoint was the exposure to quetiapine and N-dealkylquetiapine, measured using dose-corrected concentrations (C/D). The secondary endpoint was the metabolism of quetiapine to N-dealkylquetiapine, assessed by the ratio of metabolite to parent drug concentrations. The third endpoint is the differences in adverse reactions, QTc intervals, and biochemical parameters among patients with different CYP3A5 genotypes. ResultBased on the inclusion and exclusion criteria, clinical data from 207 patients were ultimately included in the study. Of these, 20 patients had the CYP3A5*1/*1 genotype, 78 had the CYP3A5*1/*3 genotype, and 109 had the CYP3A5*3/*3 genotype. The CYP3A5*3 variant was found to significantly impact the metabolism of quetiapine. The C/D values for both quetiapine and N-dealkyl quetiapine were notably higher in individuals with the *3/*3 genotype compared to those with the *1/*1 and *1/*3 genotypes (P1 < 0.001 and P2 = 0.002, respectively). A comparison of the variability in metabolic ratios among different genotype groups revealed no significant difference (P = 0.067). However, a post hoc analysis indicated that the metabolic ratio in poor metabolizers was significantly lower than that in intermediate metabolizers (P = 0.021). The analysis of adverse reaction incidence and QTc intervals among different genotypes showed no statistically significant differences (P = 0.652, P = 0.486). However, comparison of biochemical parameters across different genotype groups revealed that alanine aminotransferase, uric acid, hemoglobin, and gamma-glutamyl transferase levels were significantly higher in patients with the CYP3A5*3/*3 genotype compared to those with the CYP3A5*1/*1 and CYP3A5*1/*3 genotypes. ConclusionThe results indicated that the genetic polymorphism of CYP3A5*3 significantly influences the metabolism of quetiapine. Specifically, carriers of the CYP3A5*3/*3 genotype exhibited higher blood levels of quetiapine, with a greater likelihood of these levels exceeding the therapeutic range. This finding underscores the need for clinicians to pay special attention to the efficacy and occurrence of adverse reactions when prescribing quetiapine to patients carrying the CYP3A5*3/*3 genotype.

Population Pharmacokinetic Quantification of CYP2D6 Activity in Codeine Metabolism in Ambulatory Surgical Patients for Model-Informed Precision Dosing.

Codeine metabolism in humans is complex due to the involvement of multiple cytochrome P450 (CYP) enzymes, and has a strong genetic underpinning, which determines the levels of relevant CYP450 enzyme expression in vivo. Polymorphic CYP2D6 metabolises codeine to morphine via O-demethylation, while a strong correlation between CYP2D6 phenotype and opioidergic adverse effects of codeine is well documented. The aim of this study was to quantify the effect of CYP2D6 genotype on the biotransformation of codeine. We conducted a prospective clinical trial with 1000 patients, during which ambulatory patients were administered 60 mg of codeine preoperatively and the association between CYP2D6 activity and morphine exposure across various CYP2D6 genotypes was quantified using a population pharmacokinetic model. Plasma concentration data for codeine and its primary metabolites were obtained from 997 patients and CYP2D6 genotype was screened for study subjects, and respective sums of activity scores assigned for each CYP2D6 allele were used as covariates in model development. Our final model predicts the disposition of codeine and the formation of morphine, codeine-6-glucuronide and morphine-3-glucuronide adequately while accounting for variability in morphine exposure on the basis of CYP2D6 genotype. In agreement with previous results, patients with decreased function alleles (CYP2D6*10 and *41) showed varying levels of decrease in CYP2D6 activity that were inconsistent with increasing activity scores. Model simulations demonstrate that morphine concentrations in ultrarapid CYP2D6 metabolisers reach systemic concentrations that can potentially cause respiratory depression (over 9.1 ng/mL), and have 218% higher exposure (19 versus 8.7 µg · h/L, p < 0.001) to morphine than normal metabolisers. Similarly, poor and intermediate metabolisers had significantly reduced morphine exposure (1.0 and 3.7 versus 8.7 µg · h/L, p < 0.001) as compared with normal metabolisers. Our final model leads the way in implementing model-informed precision dosing in codeine therapy and identifies the use of genetic testing as an integral component in the effort to implement rational pharmacotherapy with codeine.

Renal Allograft Function and the Tacrolimus C/D Ratio: Insights from a Prospective Study on MeltDose Tacrolimus

Background: The tacrolimus concentration-to-dose (C/D) ratio is valuable for optimizing nephrotoxicity-related renal outcomes. Prospective data on the C/D ratio in kidney transplant recipients newly treated with MeltDose tacrolimus are limited. We analyzed the C/D ratio pattern of MeltDose tacrolimus and its effect on posttransplant renal function, comparing it with the literature data on immediate-release tacrolimus (IR-Tac). Methods: In total, 101 adult kidney transplant recipients on a standard immunosuppressive regimen including MeltDose tacrolimus were enrolled in this prospective, multicenter cohort study and followed for 12 months. The C/D ratio classified patients as fast, intermediate, or slow metabolizers. Renal function was assessed via the estimated glomerular filtration rate (eGFR). MeltDose tacrolimus data were compared with previous IR-Tac data by bootstrapping. Results: The cohort exhibited a right-skewed C/D ratio distribution with a mean of 2.12 ng/mL × 1/mg, which was significantly greater than the 1.29 mean for IR-Tac (p &lt; 0.001). Compared with fast metabolizers, slow metabolizers of MeltDose tacrolimus experienced greater eGFR gains at 6 months post-transplantation (median +7.9 vs. −3.6 mL/min; p = 0.005). A Bayesian linear mixed-effects model predicting the eGFR at month 12 identified the baseline eGFR, time from transplant, body mass index, and log-transformed C/D ratio as significant variables. A one-unit increase in the log-transformed C/D ratio corresponded to an approximate increase of 4.5 mL/min in the eGFR at month 12. Conclusions: Slow metabolizers of MeltDose tacrolimus had significantly better renal function outcomes than fast metabolizers. MeltDose tacrolimus is associated with slower metabolism than is IR-Tac, as evidenced by its higher C/D ratios.

B-222 Receptor-donor CYP3A5 and CYP3A4 genotype testing in liver transplant patients and its influence in tacrolimus blood levels: a retrospective study

Abstract Background Optimal immunosupression is crucial for transplant success. In orthohepatic transplants, blood target levels of tacrolimus, when coadministred with corticoids and mycophenolic acid, are between 6 and 10 ng/mL during the first three months post-transplant. Notwithstanding, achieving tacrolimus concentrations into this range may be tough because of factors such as liver function status, age, sex, drug-drug interactions, etc. In this way, pharmacogenetic testing of CYP3A5 and CYP3A4 genes have demonstrated to be useful in tacrolimus dosing optimization. Nonetheless, there is no evidence enough for pharmacogenetic based adjusting in liver transplant, specially if receptor and graft’s genotypes differ in these loci. The aim of the present study is to find out how the receptor and donor genotypes in CYP3A5 and CYP3A4 genes affect tacrolimus pharmacokinetics. Methods Genotypic profiling of 108 receptor-donor's pairs biopsies gathered from patients who were underwent hepatic transplant from 2012 to 2019 were carried out using Taqman® OpenArray™ PGx Express 120 panel (ThermoFisher™). We focused on CYP3A5*3, *6 and *7; and CYP3A4*1B, *3 and *22 alleles. Next to pharmacogenetic testing, each patient was classified as very poor, poor, intermediate, rapid or ultrarapid metabolizer according to their own genotype, graft’s genotype or both of them. Patient’s initial dose, at seven days after treatment start and after discharge of tacrolimus and their trough concentrations (C0) were collected from their electronic health records. Tacrolimus levels were measured by affinity chrome-mediated immunoassay. C0 was normalized by weight-adjusted dosage (C/D ratio); then, median C/D ratios between different metabolic profiles were compared through Kruskal-Wallis test. Results When patients were classified based on donor’s genotype isolated or combined with receptor’s genotype, lower C/D ratios were found as metabolizer ability increases (p=0.045 for donors and p=0.027 for combined genotypes, respectively). No statistically differences were found for C/D ratios at seven days and discharge, though that differences were almost significant for donor’s genotypes (p=0.06 in both cases). Conclusions These results show that previous information about both patient’s and specially donor’s CYP genes genotype may improve initial immunosupression and avoid tacrolimus induced toxicity. Pharmacogenetics has been currently proposed as a guide for tacrolimus treatment of some solid organ transplants as kidney transplanted patients. Better understanding of how receptor and donor’s CYP genotype affects its pharmacokinetics, along with liver’s damage markers and other genetic polymorphisms will allow clinicians, in the era of personalized medicine, to improve immunosupressive management.