Pharmacogenetics of drug-drug interaction and drug-drug-gene interaction: a systematic review on CYP2C9, CYP2C19 and CYP2D6

Physcion inhibition of CYP2C9, 2D6 and 3A4 in human liver microsomes

CONTEXT

The effect of the active ingredients in traditional Chinese medicines on the activity of cytochrome P450 enzymes (CYP450s) is a critical factor that should be considered in TCM prescriptions. Physcion, the major active ingredient of Rheum spp. (Polygonaceae), possesses wide pharmacological activities.

OBJECTIVES

The effect of physcion on CYP450 activity was investigated to provide a theoretical basis for use.

MATERIALS AND METHODS

The experiments were conducted in pooled human liver microsomes (HLMs). The activity of CYP450 isoforms was evaluated with corresponding substrates and probe reactions. Blank HLMs were set as negative controls, and typical inhibitors were employed as positive controls. The inhibition model was fitted with Lineweaver Burk plots. The concentration (0, 2.5, 5, 10, 25, 50 and 100 μM physcion) and time-dependent (0, 5, 10, 15 and 30 min) effects of physcion were also assessed.

RESULTS

Physcion suppressed CYP2C9, 2D6 and 3A4 in a concentration-dependent manner with IC50 values of 7.44, 17.84 and 13.50 μM, respectively. The inhibition of CYP2C9 and 2D6 was competitive with the Ki values of 3.69 and 8.66 μM, respectively. The inhibition of CYP3A4 was non-competitive with a Ki value of 6.70 μM. Additionally, only the inhibition of CYP3A4 was time-dependent with the KI and Kinact parameters of 3.10 μM-1 and 0.049 min-1, respectively.

CONCLUSIONS

The inhibition of CYP450s by physcion should be considered in its clinical prescription, and the study design can be employed to evaluate the interaction of CYP450s with other herbs.

Rehmannioside A inhibits the activity of CYP3A4, 2C9 and 2D6 in vitro

To assess the effect of Rehmannioside A on CYP450s activity and to estimate its inhibitory properties.The effect of Rehmannioside A on the activity of major CYP450s in human liver microsomes (HLMs) was assessed with the corresponding substrates and marker reactions, and compared with a blank control and the respective inhibitors. Suppression of CYP3A4, 2C9 and 2D6 was assessed by the dose-dependent assay and fitted with non-competitive or competitive inhibition models. The inhibition of CYP3A4 was determined in a time-dependent manner.Rehmannioside A suppressed the activity of CYP3A4, 2C9, and 2D6 with IC50 values of 10.08, 12.62, and 16.43 μM, respectively. Suppression of CYP3A4 was fitted to a non-competitive model with Ki value of 5.08 μM, whereas CYP2C9 and 2D6 were fitted to a competitive model with Ki values of 6.25 and 8.14 μM. Additionally, the inhibitory effect on CYP3A4 was time-dependent with KI value of 8.47 μM-1 and a Kinact of 0.048 min-1.In vitro suppression of CYP3A, 2C9 and 2D6 by Rehmannioside A indicated that Rehmannioside A or its source herbs may interact with drugs metabolised by these CYP450s, which could guide the clinical application.

CBD and THC in Special Populations: Pharmacokinetics and Drug-Drug Interactions

Cannabinoid use has surged in the past decade, with a growing interest in expanding cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC) applications into special populations. Consequently, the increased use of CBD and THC raises the risk of drug-drug interactions (DDIs). Nevertheless, DDIs for cannabinoids, especially in special populations, remain inadequately investigated. While some clinical trials have explored DDIs between therapeutic drugs like antiepileptic drugs and CBD/THC, more potential interactions remain to be examined. This review summarizes the published studies on CBD and THC-drug interactions, outlines the mechanisms involved, discusses the physiological considerations in pharmacokinetics (PK) and DDI studies in special populations (including pregnant and lactating women, pediatrics, older adults, patients with hepatic or renal impairments, and others), and presents modeling approaches that can describe the DDIs associated with CBD and THC in special populations. The PK of CBD and THC in special populations remain poorly characterized, with limited studies investigating DDIs involving CBD/THC in these populations. Therefore, it is critical to evaluate potential DDIs between CBD/THC and medications that are commonly used in special populations. Modeling approaches can aid in understanding these interactions.

ADME profiling, molecular docking, DFT, and MEP analysis reveal cissamaline, cissamanine, and cissamdine from Cissampelos capensis L.f. as potential anti-Alzheimer's agents

The current pharmacotherapies for Alzheimer's disease (AD) demonstrate limited efficacy and are associated with various side effects, highlighting the need for novel therapeutic agents. Natural products, particularly from medicinal plants, have emerged as a significant source of potential neuroprotective compounds. In this context, Cissampelos capensis L.f., renowned for its medicinal properties, has recently yielded three new proaporphine alkaloids; cissamaline, cissamanine, and cissamdine. Despite their promising bioactive profiles, the biological targets of these alkaloids in the context of AD have remained unexplored. This study undertakes a comprehensive in silico examination of the binding affinity and molecular interactions of these alkaloids with human protein targets implicated in AD. The drug likeness and ADME analyses indicate favorable pharmacokinetic profiles for these compounds, suggesting their potential efficacy in targeting the central nervous system. Molecular docking studies indicate that cissamaline, cissamanine, and cissamdine interact with key AD-associated proteins. These interactions are comparable to, or in some aspects slightly less potent than, those observed with established AD drugs, highlighting their potential as novel therapeutic agents for Alzheimer's disease. Crucially, Density Functional Theory (DFT) calculations offer deep insights into the electronic and energetic characteristics of these alkaloids. These calculations reveal distinct electronic properties, with differences in total energy, binding energy, HOMO-LUMO gaps, dipole moments, and electrophilicity indices. Such variations suggest unique reactivity profiles and molecular stability, pertinent to their pharmacological potential. Moreover, Molecular Electrostatic Potential (MEP) analyses provide visual representations of the electrostatic characteristics of these alkaloids. The analyses highlight areas prone to electrophilic and nucleophilic attacks, indicating their potential for specific biochemical interactions. This combination of DFT and MEP results elucidates the intricate electronic, energetic, and electrostatic properties of these compounds, underpinning their promise as AD therapeutic agents. The in silico findings of this study shed light on the promising potential of cissamaline, cissamanine, and cissamdine as agents for AD treatment. However, further in vitro and in vivo studies are necessary to validate these theoretical predictions and to understand the precise mechanisms through which these alkaloids may exert their therapeutic effects.

Landscape of pharmacogenetic variants associated with non-insulin antidiabetic drugs in the Indian population

INTRODUCTION

Genetic variants contribute to differential responses to non-insulin antidiabetic drugs (NIADs), and consequently to variable plasma glucose control. Optimal control of plasma glucose is paramount to minimizing type 2 diabetes-related long-term complications. India's distinct genetic architecture and its exploding burden of type 2 diabetes warrants a population-specific survey of NIAD-associated pharmacogenetic (PGx) variants. The recent availability of large-scale whole genomes from the Indian population provides a unique opportunity to generate a population-specific map of NIAD-associated PGx variants.

RESEARCH DESIGN AND METHODS

We mined 1029 Indian whole genomes for PGx variants, drug-drug interaction (DDI) and drug-drug-gene interactions (DDGI) associated with 44 NIADs. Population-wise allele frequencies were estimated and compared using Fisher's exact test.

RESULTS

Overall, we found 76 known and 52 predicted deleterious common PGx variants associated with response to type 2 diabetes therapy among Indians. We report remarkable interethnic differences in the relative cumulative counts of decreased and increased response-associated alleles across NIAD classes. Indians and South Asians showed a significant excess of decreased metformin response-associated alleles compared with other global populations. Network analysis of shared PGx genes predicts high DDI risk during coadministration of NIADs with other metabolic disease drugs. We also predict an increased CYP2C19-mediated DDGI risk for CYP3A4/3A5-metabolized NIADs, saxagliptin, linagliptin and glyburide when coadministered with proton-pump inhibitors (PPIs).

CONCLUSIONS

Indians and South Asians have a distinct PGx profile for antidiabetes drugs, marked by an excess of poor treatment response-associated alleles for various NIAD classes. This suggests the possibility of a population-specific reduced drug response in atleast some NIADs. In addition, our findings provide an actionable resource for accelerating future diabetes PGx studies in Indians and South Asians and reconsidering NIAD dosing guidelines to ensure maximum efficacy and safety in the population.

Factors Influencing Plasma Concentrations of Valproic Acid in Pediatric Patients with Epilepsy and the Clinical Significance of CYP2C9 Genotypes in Personalized Valproic Acid Therapy

BACKGROUND

The aim of this study was to investigate the factors affecting plasma valproic acid (VPA) concentration in pediatric patients with epilepsy and the clinical significance of CYP2C9 gene polymorphisms in personalized dosing using therapeutic drug monitoring and pharmacogenetic testing.

METHODS

The medical records of children with epilepsy who underwent therapeutic drug monitoring at our institution between July 2022 and July 2023 and met the inclusion criteria were reviewed. Statistical analysis was performed to determine whether age, sex, blood ammonia, liver function, kidney function, and other characteristics affected the concentration-to-dose ratio of VPA (CDRV) in these patients. To investigate the effect of CYP2C9 polymorphisms on CDRV, DNA samples were collected from patients and the CYP2C9 genotypes were identified using real-time quantitative PCR.

RESULTS

The mean age of 208 pediatric patients with epilepsy was 5.50 ± 3.50 years. Among these patients, 182 had the CYP2C9 *1/*1 genotype, with a mean CDRV (mcg.kg/mL.mg) of 2.64 ± 1.46, 24 had the CYP2C9 *1/*3 genotype, with a mean CDRV of 3.28 ± 1.74, and 2 had the CYP2C9 *3/*3 genotype, with a mean CDRV of 6.46 ± 3.33. There were statistical differences among these 3 genotypes (P < 0.05). The CDRV in these patients were significantly influenced by age, aspartate aminotransferase, total bilirubin, direct bilirubin, globulin, albumin/globulin ratio, prealbumin, creatinine, and CYP2C9 polymorphisms. In addition, multivariate linear regression analysis identified total bilirubin, direct bilirubin, and CYP2C9 polymorphisms as independent risk factors for high CDRV.

CONCLUSIONS

Liver problems and mutations in the CYP2C9 gene increase VPA levels. This underscores the importance of considering these factors when prescribing VPA to children with epilepsy, thereby enhancing the safety and efficacy of the therapy.

Pharmacological Effects of Urolithin A and Its Role in Muscle Health and Performance: Current Knowledge and Prospects

Urolithin A (UA) is a naturally occurring compound derived from the metabolism of gut microbiota, which has attracted considerable research attention due to its pharmacological effects and potential implications in muscle health and performance. Recent studies have demonstrated that Urolithin A exhibits diverse biological activities, encompassing anti-inflammatory, antioxidant, anti-tumor, and anti-aging properties. In terms of muscle health, accumulating evidence suggests that Urolithin A may promote muscle protein synthesis and muscle growth through various pathways, offering promise in mitigating muscle atrophy. Moreover, Urolithin A exhibits the potential to enhance muscle health and performance by improving mitochondrial function and regulating autophagy. Nonetheless, further comprehensive investigations are still warranted to elucidate the underlying mechanisms of Urolithin A and to assess its feasibility and safety in human subjects, thereby advancing its potential applications in the realms of muscle health and performance.

Application of Advanced Technologies-Nanotechnology, Genomics Technology, and 3D Printing Technology-In Precision Anesthesia: A Comprehensive Narrative Review

There has been increasing interest and rapid developments in precision medicine, which is a new medical concept and model based on individualized medicine with the joint application of genomics, bioinformatics engineering, and big data science. By applying numerous emerging medical frontier technologies, precision medicine could allow individualized and precise treatment for specific diseases and patients. This article reviews the application and progress of advanced technologies in the anesthesiology field, in which nanotechnology and genomics can provide more personalized anesthesia protocols, while 3D printing can yield more patient-friendly anesthesia supplies and technical training materials to improve the accuracy and efficiency of decision-making in anesthesiology. The objective of this manuscript is to analyze the recent scientific evidence on the application of nanotechnology in anesthesiology. It specifically focuses on nanomedicine, precision medicine, and clinical anesthesia. In addition, it also includes genomics and 3D printing. By studying the current research and advancements in these advanced technologies, this review aims to provide a deeper understanding of the potential impact of these advanced technologies on improving anesthesia techniques, personalized pain management, and advancing precision medicine in the field of anesthesia.

Pharmacogenetics and phenoconversion: the influence on side effects experienced by psychiatric patients

Introduction: Preventing side effects is important to ensure optimal psychopharmacotherapy and therapeutic adherence among psychiatric patients. Obtaining the pharmacogenetic profile of CYP2C19 and CYP2D6 can play an important role in this. When the genotype-predicted phenotype shifts because of the use of co-medication, this is called phenoconversion. The aim was to study the influence of the pharmacogenetic (PGx) profile and phenoconversion on side effects experienced by psychiatric patients. Methods: A retrospective cohort study was performed using data from 117 patients from a psychiatric outpatient clinic. Patients were genotyped with a psychiatric PGx panel and side effects were evaluated using the Udvalg for Kliniske Undersølgelser side effects rating scale (UKU). Results: Of all patients, 10.3% and 9.4% underwent phenoconversion (any shift in predicted phenotype) for CYP2C19 and CYP2D6 respectively. No significant associations were found between the phenotype and UKU-score. 75% of the patients with an Intermediate metabolizer (IM) or Poor metabolizer (PM) phenoconverted phenotype of CYP2C19 experienced nausea and vomiting compared to 9.1% of the Normal metabolizer (NM) and Ultrarapid metabolizer (UM) patients (p = 0.033). 64% of the patients with an IM or PM phenoconverted phenotype of CYP2D6 experienced the side effect depression compared to 30.4% NMs and UMs (p = 0.020). CYP2D6 IM and PM patients had a higher concentration-dose ratio than NM patients (p < 0.05). Discussion: This study underlines the importance to consider phenoconversion when looking at a patient's genotype. This is important for a better prediction of the phenotype and preventing possible side effects under a specific psychopharmacotherapy.

Identification of Drugs Acting as Perpetrators in Common Drug Interactions in a Cohort of Geriatric Patients from Southern Italy and Analysis of the Gene Polymorphisms That Affect Their Interacting Potential

BACKGROUND

Pharmacogenomic factors affect the susceptibility to drug-drug interactions (DDI). We identified drug interaction perpetrators among the drugs prescribed to a cohort of 290 older adults and analysed the prevalence of gene polymorphisms that can increase their interacting potential. We also pinpointed clinical decision support systems (CDSSs) that incorporate pharmacogenomic factors in DDI risk evaluation.

METHODS

Perpetrator drugs were identified using the Drug Interactions Flockhart Table, the DRUGBANK website, and the Mayo Clinic Pharmacogenomics Association Table. Allelic variants affecting their activity were identified with the PharmVar, PharmGKB, dbSNP, ensembl and 1000 genome databases.

RESULTS

Amiodarone, amlodipine, atorvastatin, digoxin, esomperazole, omeprazole, pantoprazole, simvastatin and rosuvastatin were perpetrator drugs prescribed to >5% of our patients. Few allelic variants affecting their perpetrator activity showed a prevalence >2% in the European population: CYP3A4/5*22, *1G, *3, CYP2C9*2 and *3, CYP2C19*17 and *2, CYP2D6*4, *41, *5, *10 and *9 and SLC1B1*15 and *5. Few commercial CDSS include pharmacogenomic factors in DDI-risk evaluation and none of them was designed for use in older adults.

CONCLUSIONS

We provided a list of the allelic variants influencing the activity of drug perpetrators in older adults which should be included in pharmacogenomics-oriented CDSSs to be used in geriatric medicine.

The ABCD-GENE score influences vascular event rates in both users of clopidogrel and aspirin, as well as non-users of either drug in a population-based cohort study

Background and Objectives

Clopidogrel is an antiplatelet used in both primary and secondary prevention of cardiovascular diseases. It is a prodrug, requiring CYP2C19 for its metabolism to the active metabolite. The ABCD-GENE score, combining clinical attributes (age, body mass index, chronic kidney disease, diabetes mellitus), with genetic information (presence of 1 or 2 loss of function (LOF) alleles in the CYP2C19 gene) has been shown to identify patients with higher risk of recurrent cardiovascular events in high-risk populations undergoing percutaneous coronary intervention. We aimed to determine if the ABCD-GENE score or LOF alleles were associated with an increased risk of vascular events among clopidogrel users in a general population.

Methods

We conducted a population based cohort study with UK Biobank's primary care prescription records to identify clopidogrel users. ABCD-GENE scores were calculated with closest available data from the first date of clopidogrel prescription. The number of LOF alleles present, and the clinical component ABCD, were separate exposures. The outcome of interest was a composite endpoint of vascular events comprised of myocardial infarction, ischemic stroke, and death due to either of these. We performed Cox proportional hazards models with clopidogrel as a time varying exposure to predict hazards of these outcomes. In order to determine the drug specificity of these exposures, the analyses were repeated in aspirin users, and in non-users of either aspirin or clopidogrel.

Results

Among 11,248 clopidogrel users, 3,365 (30%) developed a vascular event over a mean follow-up of 5.95±3.94 years. ABCD-GENE score ≥10 was associated with an increased risk of vascular events (HR 1.13, 95% CI 1.03-1.23). In aspirin users, and in non-users of either aspirin or clopidogrel, the ABCD-GENE score was also associated with increased risk of vascular events. In clopidogrel users, aspirin users, and non-users of either drug, the ABCD score was associated with increased risk of vascular events. The presence of two CYP2C19 LOF alleles was associated with an increased risk of vascular events in aspirin and non-users but not in clopidogrel users.

Discussion

In this population-based cohort study, the ABCD-GENE score was associated with an increased risk of vascular events in clopidogrel users, aspirin users, and in non-users of either drug. The clinical component, ABCD was also associated with an increased risk of vascular events in all three groups. This suggests that the ABCD-GENE score is not specific to clopidogrel users in identifying persons at high risk of vascular events in a general sample with low baseline CYP2C19 LOF allele frequency.

Pharmacogenomics: Driving Personalized Medicine

Personalized medicine tailors therapies, disease prevention, and health maintenance to the individual, with pharmacogenomics serving as a key tool to improve outcomes and prevent adverse effects. Advances in genomics have transformed pharmacogenetics, traditionally focused on single gene-drug pairs, into pharmacogenomics, encompassing all "-omics" fields (e.g., proteomics, transcriptomics, metabolomics, and metagenomics). This review summarizes basic genomics principles relevant to translation into therapies, assessing pharmacogenomics' central role in converging diverse elements of personalized medicine. We discuss genetic variations in pharmacogenes (drug-metabolizing enzymes, drug transporters, and receptors), their clinical relevance as biomarkers, and the legacy of decades of research in pharmacogenetics. All types of therapies, including proteins, nucleic acids, viruses, cells, genes, and irradiation, can benefit from genomics, expanding the role of pharmacogenomics across medicine. Food and Drug Administration approvals of personalized therapeutics involving biomarkers increase rapidly, demonstrating the growing impact of pharmacogenomics. A beacon for all therapeutic approaches, molecularly targeted cancer therapies highlight trends in drug discovery and clinical applications. To account for human complexity, multicomponent biomarker panels encompassing genetic, personal, and environmental factors can guide diagnosis and therapies, increasingly involving artificial intelligence to cope with extreme data complexities. However, clinical application encounters substantial hurdles, such as unknown validity across ethnic groups, underlying bias in health care, and real-world validation. This review address the underlying science and technologies germane to pharmacogenomics and personalized medicine, integrated with economic, ethical, and regulatory issues, providing insights into the current status and future direction of health care. SIGNIFICANCE STATEMENT: Personalized medicine aims to optimize health care for the individual patients with use of predictive biomarkers to improve outcomes and prevent adverse effects. Pharmacogenomics drives biomarker discovery and guides the development of targeted therapeutics. This review addresses basic principles and current trends in pharmacogenomics, with large-scale data repositories accelerating medical advances. The impact of pharmacogenomics is discussed, along with hurdles impeding broad clinical implementation, in the context of clinical care, ethics, economics, and regulatory affairs.

Association of CYP2C19, CYP2D6 and CYP3A4 Genetic Variants on Primaquine Hemolysis in G6PD-Deficient Patients

In the Amazon, the treatment for Plasmodium vivax is chloroquine plus primaquine. However, this regimen is limited due to the risk of acute hemolytic anemia in glucose-6-phosphate dehydrogenase deficiency. Primaquine is a prodrug that requires conversion by the CYP2D6 enzyme to be effective against malaria. A series of cases were performed at an infectious diseases reference hospital in the Western Brazilian Amazon. The STANDARD G6PD (SD Biosensor^®) assay was used to infer G6PD status and real-time PCR to genotype G6PD, CYP2C19, CYP2D6 and CYP3A4. Eighteen patients were included, of which 55.6% had African A- variant (G202A/A376G), 11.1% African A+ variant (A376G), 5.6% Mediterranean variant (C563T) and 27.8% were wild type. CYP2C19, CYP2D6 and CYP3A4 genotyping showed no statistically significant differences in the frequency of star alleles between the groups G6PD deficient and G6PD normal. Elevated levels of liver and kidney markers in the G6PDd patients were observed in gNM, gRM and gUM of CYP2C19 and CYP2D6 (p < 0.05). Furthermore, in this study there was no influence of CYPs on hemolysis. These findings reinforce the importance of studies on the mapping of G6PD deficiency and genetic variations of CYP2C19, CYP2D6 and CYP3A4. This mapping will allow us to validate the prevalence of CYPs and determine their influence on hemolysis in patients with malaria, helping to decide on the treatment regimen.

Pharmacokinetic interaction of voriconazole and clarithromycin in Pakistani healthy male volunteers: a single dose, randomized, crossover, open-label study

Background: Voriconazole an antifungal drug, has a potential for drug-drug interactions (DDIs) with administered drugs. Clarithromycin is a Cytochromes P450 CYP (3A4 and 2C19) enzyme inhibitor, and voriconazole is a substrate and inhibitor of these two enzymes. Being a substrate of the same enzyme for metabolism and transport, the chemical nature and pKa of both interacting drugs make these drugs better candidates for potential pharmacokinetic drug-drug interactions (PK-DDIs). This study aimed to evaluate the effect of clarithromycin on the pharmacokinetic profile of voriconazole in healthy volunteers. Methods: A single oral dose, open-label, randomized, crossover study was designed for assessing PK-DDI in healthy volunteers, consisting of 2 weeks washout period. Voriconazole, either alone (2 mg × 200 mg, tablet, P/O) or along with clarithromycin (voriconazole 2 mg × 200 mg, tablet + clarithromycin 500 mg, tablet, P/O), was administered to enrolled volunteers in two sequences. The blood samples (approximately 3 cc) were collected from volunteers for up to 24 h. Plasma concentrations of voriconazole were analyzed by an isocratic, reversed-phase high-performance-liquid chromatography ultraviolet-visible detector (RP HPLC UV-Vis) and a non-compartmental method. Results: In the present study, when voriconazole was administered with clarithromycin versus administered alone, a significant increase in peak plasma concentration (Cmax) of voriconazole by 52% (geometric mean ratio GMR: 1.52; 90% CI 1.04, 1.55; p = 0.000) was observed. Similarly, the area under the curve from time zero to infinity (AUC^0-∞) and the area under the concentration-time curve from time zero to time-t (AUC^0-t) of voriconazole also significantly increased by 21% (GMR: 1.14; 90% CI 9.09, 10.02; p = 0.013), and 16% (GMR: 1.15; 90% CI 8.08, 10.02; p = 0.007), respectively. In addition, the results also showed a reduction in the apparent volume of distribution (Vd) by 23% (GMR: 0.76; 90% CI 5.00, 6.20; p = 0.051), and apparent clearance (CL) by 13% (GMR: 0.87; 90% CI 41.95, 45.73; p = 0.019) of voriconazole. Conclusion: The alterations in PK parameters of voriconazole after concomitant administration of clarithromycin are of clinical significance. Therefore, adjustments in dosage regimens are warranted. In addition, extreme caution and therapeutic drug monitoring are necessary while co-prescribing both drugs. Clinical Trial Registration: clinicalTrials.gov, Identifier NCT05380245.

The impact of CYP2C19 genotype on phenoconversion by concomitant medication

Introduction: Pharmacogenetics-informed drug prescribing is increasingly applied in clinical practice. Typically, drug metabolizing phenotypes are determined based on genetic test results, whereupon dosage or drugs are adjusted. Drug-drug-interactions (DDIs) caused by concomitant medication can however cause mismatches between predicted and observed phenotypes (phenoconversion). Here we investigated the impact of CYP2C19 genotype on the outcome of CYP2C19-dependent DDIs in human liver microsomes. Methods: Liver samples from 40 patients were included, and genotyped for CYP2C19*2, *3 and *17 variants. S-mephenytoin metabolism in microsomal fractions was used as proxy for CYP2C19 activity, and concordance between genotype-predicted and observed CYP2C19 phenotype was examined. Individual microsomes were subsequently co-exposed to fluvoxamine, voriconazole, omeprazole or pantoprazole to simulate DDIs. Results: Maximal CYP2C19 activity (V_max) in genotype-predicted intermediate metabolizers (IMs; *1/*2 or *2/*17), rapid metabolizers (RMs; *1/*17) and ultrarapid metabolizers (UMs; *17/*17) was not different from V_max of predicted normal metabolizers (NMs; *1/*1). Conversely, CYP2C19*2/*2 genotyped-donors exhibited V_max rates ∼9% of NMs, confirming the genotype-predicted poor metabolizer (PM) phenotype. Categorizing CYP2C19 activity, we found a 40% concordance between genetically-predicted CYP2C19 phenotypes and measured phenotypes, indicating substantial phenoconversion. Eight patients (20%) exhibited CYP2C19 IM/PM phenotypes that were not predicted by their CYP2C19 genotype, of which six could be linked to the presence of diabetes or liver disease. In subsequent DDI experiments, CYP2C19 activity was inhibited by omeprazole (-37% ± 8%), voriconazole (-59% ± 4%) and fluvoxamine (-85% ± 2%), but not by pantoprazole (-2 ± 4%). The strength of CYP2C19 inhibitors remained unaffected by CYP2C19 genotype, as similar percental declines in CYP2C19 activity and comparable metabolism-dependent inhibitory constants (K_inact/K_I) of omeprazole were observed between CYP2C19 genotypes. However, the consequences of CYP2C19 inhibitor-mediated phenoconversion were different between CYP2C19 genotypes. In example, voriconazole converted 50% of *1/*1 donors to a IM/PM phenotype, but only 14% of *1/*17 donors. Fluvoxamine converted all donors to phenotypic IMs/PMs, but *1/*17 (14%) were less likely to become PMs than *1/*1 (50%) or *1/*2 and *2/*17 (57%). Conclusion: This study suggests that the differential outcome of CYP2C19-mediated DDIs between genotypes are primarily dictated by basal CYP2C19 activity, that may in part be predicted by CYP2C19 genotype but likely also depends on disease-related factors.

Long-term deprescription in chronic pain and opioid use disorder patients: Pharmacogenetic and sex differences

More than half of patients with opioid use disorder for chronic non-cancer pain (CNCP) reduced their dose through a progressive opioid withdrawal supported by a rotation to buprenorphine and/or tramadol. The aim of this research is to analyse the long-term effectiveness of opioid deprescription taking into account the impact of sex and pharmacogenetics on the inter-individual variability. A cross-sectional study was carried out from October 2019 to June 2020 on CNCP patients who had previously undergone an opioid deprescription (n = 119 patients). Demographic, clinical (pain, relief and adverse events) and therapeutic (analgesic use) outcomes were collected. Effectiveness (< 50 mg per day of morphine equivalent daily dose without any aberrant opioid use behaviour) and safety (number of side-effects) were analysed in relation to sex differences and pharmacogenetic markers impact [OPRM1 genotype (rs1799971) and CYP2D6 phenotypes]. Long-term opioid deprescription was achieved in 49 % of the patients with an increase in pain relief and a reduction of adverse events. CYP2D6 poor metabolizers showed the lowest long-term opioid doses. Here, women showed a higher degree of opioid deprescription, but increased use of tramadol and neuromodulators, as well as an increased number of adverse events. Long-term deprescription was successful in half of the cases. Understanding sex and gender interaction plus a genetic impact could help to design more individualized strategies for opioid deprescription.

The Role of Pharmacogenetics in Personalizing the Antidepressant and Anxiolytic Therapy

Pharmacotherapy for neuropsychiatric disorders, such as anxiety and depression, has been characterized by significant inter-individual variability in drug response and the development of side effects. Pharmacogenetics, as a key part of personalized medicine, aims to optimize therapy according to a patient's individual genetic signature by targeting genetic variations involved in pharmacokinetic or pharmacodynamic processes. Pharmacokinetic variability refers to variations in a drug's absorption, distribution, metabolism, and elimination, whereas pharmacodynamic variability results from variable interactions of an active drug with its target molecules. Pharmacogenetic research on depression and anxiety has focused on genetic polymorphisms affecting metabolizing cytochrome P450 (CYP) and uridine 5'-diphospho-glucuronosyltransferase (UGT) enzymes, P-glycoprotein ATP-binding cassette (ABC) transporters, and monoamine and γ-aminobutyric acid (GABA) metabolic enzymes, transporters, and receptors. Recent pharmacogenetic studies have revealed that more efficient and safer treatments with antidepressants and anxiolytics could be achieved through genotype-guided decisions. However, because pharmacogenetics cannot explain all observed heritable variations in drug response, an emerging field of pharmacoepigenetics investigates how epigenetic mechanisms, which modify gene expression without altering the genetic code, might influence individual responses to drugs. By understanding the epi(genetic) variability of a patient's response to pharmacotherapy, clinicians could select more effective drugs while minimizing the likelihood of adverse reactions and therefore improve the quality of treatment.

The investigation of the complex population-drug-drug interaction between ritonavir-boosted lopinavir and chloroquine or ivermectin using physiologically-based pharmacokinetic modeling

OBJECTIVES

Therapy failure caused by complex population-drug-drug (PDDI) interactions including CYP3A4 can be predicted using mechanistic physiologically-based pharmacokinetic (PBPK) modeling. A synergy between ritonavir-boosted lopinavir (LPVr), ivermectin, and chloroquine was suggested to improve COVID-19 treatment. This work aimed to study the PDDI of the two CYP3A4 substrates (ivermectin and chloroquine) with LPVr in mild-to-moderate COVID-19 adults, geriatrics, and pregnancy populations.

METHODS

The PDDI of LPVr with ivermectin or chloroquine was investigated. Pearson's correlations between plasma, saliva, and lung interstitial fluid (ISF) levels were evaluated. Target site (lung epithelial lining fluid [ELF]) levels of ivermectin and chloroquine were estimated.

RESULTS

Upon LPVr coadministration, while the chloroquine plasma levels were reduced by 30, 40, and 20%, the ivermectin plasma levels were increased by a minimum of 425, 234, and 453% in adults, geriatrics, and pregnancy populations, respectively. The established correlation equations can be useful in therapeutic drug monitoring (TDM) and dosing regimen optimization.

CONCLUSIONS

Neither chloroquine nor ivermectin reached therapeutic ELF levels in the presence of LPVr despite reaching toxic ivermectin plasma levels. PBPK modeling, guided with TDM in saliva, can be advantageous to evaluate the probability of reaching therapeutic ELF levels in the presence of PDDI, especially in home-treated patients.

In Vitro Investigation on the Effect of Dendrobine on the Activity of Cytochrome P450 Enzymes

Dendrobine is the major active ingredient of Dendrobium nobile, Dendrobium chrysotoxum, and Dendrobium fimbriatum, all of which are used in traditional Chinese medicine owing to their antitumor and anti-inflammation activities. Hence, investigation on the interaction of dendrobine with cytochrome P450 enzymes could provide a reference for the clinical application of Dendrobium. The effects of dendrobine on cytochrome P450 enzymes activities were investigated in the presence of 0, 2.5, 5, 10, 25, 50, and 100 µM dendrobine in pooled human liver microsomes. The specific inhibitors were employed as the positive control and the blank groups were set as the negative control. The Lineweaver-Burk plots were plotted to characterize the specific inhibition model and obtain the kinetic parameters. The study reveals that dendrobine significantly inhibited the activity of CYP3A4, 2C19, and 2D6 with IC₅₀ values of 12.72, 10.84, and 15.47 µM, respectively. Moreover, the inhibition of CYP3A4 was found to be noncompetitive (Ki = 6.41 µM) and time dependent (KI = 2.541 µM^-1, Kinact  = 0.0452 min^-1), while the inhibition of CYP2C19 and 2D6 was found to be competitive with the Ki values of 5.22 and 7.78 µM, respectively, and showed no time-dependent trends. The in vitro inhibitory effect of dendrobine implies the potential drug-drug interaction between dendrobine and CYP3A4-, 2C9-, and 2D6-metabolized drugs. Nonetheless, these findings need further in vivo validation.

Drug-Drug-Gene Interactions in Cardiovascular Medicine

Cardiovascular disease remains a leading cause of both morbidity and mortality worldwide. It is widely accepted that both concomitant medications (drug-drug interactions, DDIs) and genomic factors (drug-gene interactions, DGIs) can influence cardiovascular drug-related efficacy and safety outcomes. Although thousands of DDI and DGI (aka pharmacogenomic) studies have been published to date, the literature on drug-drug-gene interactions (DDGIs, cumulative effects of DDIs and DGIs) remains scarce. Moreover, multimorbidity is common in cardiovascular disease patients and is often associated with polypharmacy, which increases the likelihood of clinically relevant drug-related interactions. These, in turn, can lead to reduced drug efficacy, medication-related harm (adverse drug reactions, longer hospitalizations, mortality) and increased healthcare costs. To examine the extent to which DDGIs and other interactions influence efficacy and safety outcomes in the field of cardiovascular medicine, we review current evidence in the field. We describe the different categories of DDIs and DGIs before illustrating how these two interact to produce DDGIs and other complex interactions. We provide examples of studies that have reported the prevalence of clinically relevant interactions and the most implicated cardiovascular medicines before outlining the challenges associated with dealing with these interactions in clinical practice. Finally, we provide recommendations on how to manage the challenges including but not limited to expanding the scope of drug information compendia, interaction databases and clinical implementation guidelines (to include clinically relevant DDGIs and other complex interactions) and work towards their harmonization; better use of electronic decision support tools; using big data and novel computational techniques; using clinically relevant endpoints, preemptive genotyping; ensuring ethnic diversity; and upskilling of clinicians in pharmacogenomics and personalized medicine.

Performance Verification of CYP2C19 Enzyme Abundance Polymorphism Settings within the Simcyp Simulator v21

Physiologically based pharmacokinetic (PBPK) modeling has a number of applications, including assessing drug−drug interactions (DDIs) in polymorphic populations, and should be iteratively refined as science progresses. The Simcyp Simulator is annually updated and version 21 included updates to hepatic and intestinal CYP2C19 enzyme abundance, including addition of intermediate and rapid metabolizer phenotypes and changes to the ultra-rapid metabolizer enzyme abundance, with implications for population clearance and DDI predictions. This work details verification of the updates with sensitive CYP2C19 substrates, omeprazole and lansoprazole, using available clinical data from literature. Multiple assessments were performed, including recovery of areas under the concentration-time curve (AUC) and Cmax from compiled datasets for each drug, recovery of victim DDI ratios with CYP2C19 and/or CYP3A4 inhibition and recovery of relative exposure between phenotypes. Simulated data were within respective acceptance criteria for >80% of omeprazole AUC values, >70% of lansoprazole AUC and Cmax, >60% of AUC and Cmax DDI ratios and >80% of exposure ratios between different phenotypes. Recovery of omeprazole Cmax was lower (>50−70% within 2-fold) and possibly attributed to the variety of formulations used in the clinical dataset. Overall, the results demonstrated that the updated data used to parameterize CYP2C19 phenotypes reasonably described the pharmacokinetics of omeprazole and lansoprazole in genotyped or phenotyped individuals.

CYP2C19 and CYP2D6 Genotypes and Metabolizer Status Distribution in a Bulgarian Psychiatric Cohort

CYP2D6 and CYP2C19 are enzymes of essential significance for the pharmacokinetics of a multitude of commonly used antidepressants, antipsychotics, antiemetics, β-blockers, opioids, antiestrogen, antacids, etc. Polymorphisms in the respective genes are well established as resulting in functional differences, which in turn can impact safety and efficacy. Importantly, the prevalence of genetic CYP2D6 and CYP2C19 variability differs drastically between populations. Drawing on the limited information concerning genotype frequencies in Bulgaria, we here analyzed 742 Bulgarian psychiatric patients predominantly diagnosed with depression and/or anxiety. Specifically, we analyzed frequencies of CYPC19*2, *4 and *17, as well as of CYP2D6*2, *3, *4, *5, *6, *10 and *41. In total, 571 out of 742 patients (77%) carried at least one variant which impacts metabolizer status. Overall, 48.6% of the studied individuals were classified as non-normal metabolizers of CYP2D6 with most exhibiting reduced function (38.2% intermediate metabolizers and 6.6% poor metabolizers). In contrast, for CYP2C19, the majority of non-normal metabolizers showed increased functionality (28.9% rapid and 5.5% ultrarapid metabolizers), while reduced activity metabolizer status accounted for 25.6% (23.8% intermediate and 1.8% poor metabolizers). These results provide an important resource to assess the genetically encoded functional variability of CYP2D6 and CYP2C19 which may have significant implications for precision medicine in Bulgarian psychiatry practice.

Fluoroalkylation of Dextromethorphan Improves CNS Exposure and Metabolic Stability

Aryl-methyl ethers, while present in many bioactive compounds, are subject to rapid O-dealkylation, which can generate bioinactive or toxic metabolites. Such is the case for dextromethorphan, which readily undergoes P450 mediated O-dealkylation to provide the psychoactive phenolic metabolite dextrorphan, an N-methyl-d-aspartate (NMDA) receptor antagonist that causes hallucinations and encourages recreational abuse. As a general strategy to minimize this undesired degradation, both deuteration and fluorination strategies might be exploited, though such strategies have rarely been compared in matched series. In this manuscript, we designed, synthesized, and evaluated in vitro and in vivo new fluoroalkyl analogs of dextromethorphan and D₃-dextromethorphan that minimize metabolic degradation and increased CNS exposure relative to dextromethorphan and related deuterated analogs currently in clinical trials.

ZY12201, A Potent TGR5 Agonist: Identification of a Novel Pan CYP450 Inhibitor Tool Compound for In-Vitro Assessment

BACKGROUND

Identification of clinical drug-drug interaction (DDI) risk is an important aspect of drug discovery and development owing to poly-pharmacy in present-day clinical therapy. Drug metabolizing enzymes (DME) plays important role in the efficacy and safety of drug candidates. Hence evaluation of a New Chemical Entity (NCE) as a victim or perpetrator is very crucial for DDI risk mitigation. ZY12201 (2-((2-(4-(1H-imidazol-1-yl) phenoxy) ethyl) thio)-5-(2-(3, 4- dimethoxy phenyl) propane-2-yl)-1-(4-fluorophenyl)-1H-imidazole) is a novel and potent Takeda-G-protein-receptor-5 (TGR-5) agonist. ZY12201 was evaluated in-vitro to investigate the DDI liabilities.

OBJECTIVE

The key objective was to evaluate the CYP inhibition potential of ZY12201 for an opportunity to use it as a tool compound for pan CYP inhibition activities.

METHOD

In-vitro drug metabolizing enzymes (DME) inhibition potential of ZY12201 was evaluated against major CYP isoforms (1A2, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4/5), aldehyde oxidase (AO), monoamine oxidase (MAO), and flavin-containing monooxygenase (FMO in human liver cytosol/mitochondrial preparation/ microsomes using probe substrates and Liquid Chromatography with tandem mass spectrometry (LC-MS-MS) method.

RESULTS

The study conducted on ZY12201 at 100 µM ZY12201 was found to reduce the metabolism of vanillin (AO probe substrate), tryptamine (MAO probe substrate), and benzydamine (FMO probe substrate) by 49.2%, 14.7%, and 34.9%, respectively. ZY12201 Ki values were 0.38, 0.25, 0.07, 0.01, 0.06, 0.02, 7.13, 0.03 and 0.003 μM for CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4/5 (substrate: testosterone) and CYP3A4/5 (substrate: midazolam), respectively. Time-dependant CYP inhibition potential of ZY12201 was assessed against CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4/5 and no apparent IC50 shift was observed.

CONCLUSIONS

ZY12201, at 100 µM concentration showed low inhibition potential of AO, MAO, and FMO. ZY12201 was found as a potent inhibitor of CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4/5 while moderately inhibits to CYP2E1. Inhibition of CYP1A2, CYP2B6, CYP2C19, and CYP2E1 by ZY12201 was competitive, while inhibition of CYP2C8, CYP2C9, CYP2D6, and CYP3A4/5 was of mixed-mode. ZY12201 is a non-time-dependent inhibitor of CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4/5. In summary, the reported Ki values unequivocally support that ZY12201 has a high potential to inhibit all major CYP isoforms. ZY12201 can be effectively used as a tool compound for in-vitro evaluation of CYP-based metabolic contribution to total drug clearance in the lead optimization stage of Drug Discovery Research.

Evaluation of CYP2C19 activity using microdosed oral omeprazole in humans

Purpose

To investigate the suitability of microdosed oral omeprazole for predicting CYP2C19 activity in vivo in combination with simultaneous assessment of CYP3A and CYP2D6 activity using both microdosed midazolam and yohimbine.

Methods

An open, fixed-sequence study was carried out in 20 healthy participants. Single microdosed (100 µg) and therapeutic (20 mg) doses of omeprazole were evaluated without comedication and after administration of established CYP2C19 perpetrators fluconazole (inhibition) and rifampicin (induction). To prevent degradation of the uncoated omeprazole microdose, sodium bicarbonate buffer was administered. The pharmacokinetics of omeprazole and its 5-hydroxy-metabolite were assessed as well as the pharmacokinetics of midazolam and yohimbine to estimate CYP3A4 and CYP2D6 activity.

Results

Calculated pharmacokinetic parameters after administration of 100 µg and 20 mg omeprazole in healthy subjects suggest dose proportionality. Omeprazole clearance was significantly decreased by fluconazole from 388 [95% CI: 266–565] to 47.2 [42.8–52.0] mL/min after 20 mg omeprazole and even further after 100 µg omeprazole (29.4 [24.5–35.1] mL/min). Rifampicin increased CYP2C19-mediated omeprazole metabolism. The omeprazole hydroxylation index was significantly related to omeprazole clearance for both doses. Both fluconazole and rifampicin altered CYP3A4 activity whereas no change of CYP2D6 activity was observed at all.

Conclusions

Microdosed oral omeprazole is suitable to determine CYP2C19 activity, also during enzyme inhibition and induction. However, the administration of sodium bicarbonate buffer also had a small influence on all victim drugs used.

Trial registration

EudraCT: 2017–004270-34.

Supplementary information

The online version contains supplementary material available at 10.1007/s00228-022-03304-3.

In vitro evaluation of the inhibition potential of echinacoside on human cytochrome P450 isozymes

Background

Echinacoside (ECH) possesses a wide range of biological activity. This present study analyzes the effect of ECH on cytochrome P450 isozymes (CYPs) activities of human liver microsomes.

Methods

The effect of ECH on CYPs enzyme activities were studied using the enzyme-selective substrates phenacetin (1A2), chlorzoxazone (2E1), S-mephenytoin (2C19), testosterone (3A4), coumarin (2A6), diclofenac (2C9), paclitaxel (2C8), and dextromethorphan (2D6). The IC50 values for CYP1A2, CYP2E1, CYP2C19, and CYP3A4 isoforms were examined to express the strength of inhibition. Further, the inhibition of CYPs was checked for time-dependent or not, and then fitted with competitive or non-competitive inhibition models. The corresponding parameters were also obtained.

Results

ECH caused inhibitions on CYP1A2, CYP2E1, CYP2C19 and CYP3A4 enzyme activities in HLMs with IC50 of 21.23, 19.15, 8.70 and 55.42 μM, respectively. The obtained results showed that the inhibition of ECH on CYP3A4 was time-dependent with the KI/K_inact value of 6.63/0.066 min^− 1·μM^− 1. Moreover, ECH inhibited the activity of CYP1A2 and CYP2E1 via non-competitive manners (K_i = 10.90 μM and K_i = 14.40 μM, respectively), while ECH attenuated the CYP2C19 activity via a competitive manner (K_i = 4.41 μM).

Conclusions

The results of this study indicate that ECH inhibits CYP1A2, CYP2E1, CYP2C19 and CYP3A4 activities in vitro. In vivo and clinical studies are warranted to verify the relevance of these interactions.

Unexpected severe hepatic and skin toxicities during high dose methotrexate course for osteosarcoma

INTRODUCTION

high dose methotrexate (HD-MTX) regimen is used in osteosarcoma, leukemia and lymphoma treatment. Osteosarcoma is mostly diagnosed in children and adolescents. Most frequent methotrexate toxicities are mucositis, myelosuppression, renal failure, hepatitis and necrotizing encephalopathy. Toxicities increase with renal impairment, denutrition, in older patients, with some pharmacogenetics factors or with drug interactions.

CASE REPORT

We report a 16th years old woman diagnosed with osteosarcoma and experienced an unexpected severe hepatic and skin toxicities as toxic epidermal necrolys, Steven Johnson syndrome.

MANAGEMENT AND OUTCOME

This toxicity occurred despite acid folinic rescue performed as good practice recommendation. Fourteen hours after methotrexate administration, renal failure was observed and after 72 h an erythematous rash and epidermal detachment with toxic epidermal necrolys. Seven days after methotrexate administration, hepatic failure began until grade IV cytolysis. High dose of folinic acid were administered during all severe toxicities. Methotrexate were not longer administered to this young patient and chemotherapy with ifosfamide (IFO), doxorubicine and cisplatin were performed in this patient and complete histologic response were observed in the surgical bone resection.

DISCUSSION

No classical toxicities risk factors were identified in this patient but a homozygote mutation of MTHFR gene and homozygote SLCO1B1 gene mutation were found. MTHFR and SLCO1B1 are both implicated in methotrexate metabolism.

The interplay between pharmacogenetics, concomitant drugs and blood levels of amitriptyline and its main metabolites

Background: The research considers the impact of genotype-inferred variability on blood levels of amitriptyline and its main metabolites, as may be moderated by phenocopying. Patients & methods: CYP2D6 and CYP2C19 genotypes, and serum concentrations of amitriptyline, nortriptyline and hydroxymetabolites, were determined in 33 outpatients. Co-medications were reviewed to identify CYP inhibition risk. Results: CYP2C19 metabolizer status explained interpatient variation in nortriptyline to amitriptyline concentration ratios. The hydroxymetabolite to parent ratios increased with higher CYP2D6 activity scores and lower CYP2D6 inhibition risk. In patients at high CYP2D6 inhibition risk, the amitriptyline + nortriptyline concentration was, on average, 52% above the higher end of expected ranges. Conclusion: Practical construal of pharmacogenetics and drug interactions tantamount to aberrant metabolism can facilitate patient-tailored use of the established drug.

Ten Years of Experience Support Pharmacogenetic Testing to Guide Individualized Drug Therapy

Precision medicine utilizing the genetic information of genes involved in the metabolism and disposition of drugs can not only improve drug efficacy but also prevent or minimize adverse events. Polypharmacy is common among multimorbid patients and is associated with increased adverse events. One of the main objectives in health care is safe and efficacious drug therapy, which is directly correlated to the individual response to treatment. Precision medicine can increase drug safety in many scenarios, including polypharmacy. In this report, we share our experience utilizing precision medicine over the past ten years. Based on our experience using pharmacogenetic (PGx)-informed prescribing, we implemented a five-step precision medicine protocol (5SPM) that includes the assessment of the biological-clinical characteristics of the patient, current and past prescription history, and the patient's PGx test results. To illustrate our approach, we present cases highlighting the clinical relevance of precision medicine with a focus on patients with a complex history and polypharmacy.

Drug-Drug Interactions in Vestibular Diseases, Clinical Problems, and Medico-Legal Implications

Peripheral vestibular disease can be treated with several approaches (e.g., maneuvers, surgery, or medical approach). Comorbidity is common in elderly patients, so polytherapy is used, but it can generate the development of drug-drug interactions (DDIs) that play a role in both adverse drug reactions and reduced adherence. For this reason, they need a complex kind of approach, considering all their individual characteristics. Physicians must be able to prescribe and deprescribe drugs based on a solid knowledge of pharmacokinetics, pharmacodynamics, and clinical indications. Moreover, full information is required to reach a real therapeutic alliance, to improve the safety of care and reduce possible malpractice claims related to drug-drug interactions. In this review, using PubMed, Embase, and Cochrane library, we searched articles published until 30 August 2021, and described both pharmacokinetic and pharmacodynamic DDIs in patients with vestibular disorders, focusing the interest on their clinical implications and on risk management strategies.

Effects of 31 recombinant CYP2C19 variants on clomipramine metabolism in vitro

BACKGROUND

CYP2C19 is an important member of the cytochrome P450 enzyme superfamily. We recently identified 31CYP2C19 alleles in the Han Chinese population; studying the effects of CYP2C19 on drug metabolism can help reduce adverse drug reactions and therapeutic failure.

AIM

The aim of this study was to assess the catalytic activities of 31 allelic isoforms and their effects on the metabolism of clomipramine in vitro.

METHODS

The wild-type and 30 CYP2C19 variants were expressed in insect cells, and each variant was characterized using clomipramine as the substrate. Reactions were performed at 37°C with 5-150 μmol/L substrate for 30 min. By using ultra-high-performance liquid chromatography-mass spectrometry to detect the products, the kinetic parameters Km, Vmax, and intrinsic clearance (Vmax/Km) of N-desmethyl clomipramine were determined.

RESULTS

Among the CYP2C19 variants tested, CYP2C19*29, L16F, and T130M showed extremely increased intrinsic clearance of clomipramine, CYP2C19*3C, and N277K showed similar intrinsic clearance (Vmax/Km) values with CYP2C19*1, while the intrinsic clearance values of other variants were significantly decreased (from 0.65% to 63.28%). In addition, CYP2C19*3 and 35FS could not be detected because they have no detectable enzyme activity.

CONCLUSIONS

As the first report of 31 CYP2C19 alleles for clomipramine metabolism, our study could provide corresponding reference for clomipramine for further studies in vivo and offer valuable information relevant to the personalized medicine for CYP2C19-metabolized drug.

Functional evaluation of vandetanib metabolism by CYP3A4 variants and potential drug interactions in vitro

AIM

To investigate the enzymatic properties of cytochrome P450 3A4 (CYP3A4) variants and their ability to metabolize vandetanib (VNT) in vitro, and to study potential drug interactions in combination with VNT.

METHOD

Recombinant CYP3A4 cell microsomes were prepared using a Bac-to-Bac baculovirus expression system. Enzymatic reactions were carried out, and the metabolites were determined by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS).

RESULTS

The activities of 27 CYP3A4 variants were determined to assess the degree of VNT metabolism that occurred. Analysis indicated that there was enhanced intrinsic clearance (V_max/K_m, CLint) for eight variants (CYP3A4.2, 3, 9, 15, 16, 29, 32, and 33), while there was a significant decrease in CYP3A4.5, 7, 8, 10-14, 17-20, 23, 24, 28, 31, and 34. Compared with CYP3A4.1, no significant differences were found for CYP3A4.6 and 30. Furthermore, the relative clearances were compared between VNT and cabozantinib, which were all metabolized by CYP3A4 with the same indications. When combined with ketoconazole, which is a CYP inhibitor, obvious differences were observed in the potency of VNT between different variants, including CYP3A4.2, 15, and 18.

CONCLUSION

This comprehensive assessment of CYP3A4 variants provides significant insights into the allele-specific metabolism of VNT and drug interactions in vitro. We hope that these comprehensive data will provide references and predictions for the clinical application of VNT.

Differential Interactions of Selected Phytocannabinoids with Human CYP2D6 Polymorphisms

Cytochrome P450 2D6 (CYP2D6) is primarily expressed in the liver and in the central nervous system. It is known to be highly polymorphic in nature. It metabolizes several endogenous substrates such as anandamide (AEA). Concomitantly, it is involved in phase 1 metabolism of several antidepressants, antipsychotics, and other drugs. Research in the field of phytocannabinoids (pCBs) has recently accelerated owing to their legalization and increasing medicinal use for pain and inflammation. The primary component of cannabis is THC, which is well-known for its psychotropic effects. Since CYP2D6 is an important brain and liver P450 and is known to be inhibited by CBD, we investigated the interactions of four important highly prevalent CYP2D6 polymorphisms with selected phytocannabinoids (CBD, THC, CBDV, THCV, CBN, CBG, CBC, β-carophyllene) that are rapidly gaining popularity. We show that there is differential binding of CYP2D6*17 to pCBs as compared to WT CYP2D6. We also perform a more detailed comparison of WT and *17 CYP2D6, which reveals the possible regulation of AEA metabolism by CBD. Furthermore, we use molecular dynamics to delineate the mechanism of this binding, inhibition, and regulation. Taken together, we have found that the interactions of CYP2D6 with pCBs vary by polymorphism and by specific pCB class.

Comparison of Multidrug Use in the General Population and among Persons with Diabetes in Denmark for Drugs Having Pharmacogenomics (PGx) Based Dosing Guidelines

Background: This study measures the use of drugs within the therapeutic areas of antithrombotic agents (B01), the cardiovascular system (C), analgesics (N02), psycholeptics (N05), and psychoanaleptics (N06) among the general population (GP) in comparison to persons with diabetes in Denmark. The study focuses on drugs having pharmacogenomics (PGx) based dosing guidelines for CYP2D6, CYP2C19, and SLCO1B1 to explore the potential of applying PGx-based decision-making into clinical practice taking drug–drug interactions (DDI) and drug–gene interactions (DGI) into account. Methods: This study is cross-sectional, using The Danish Register of Medicinal Product Statistics as the source to retrieve drug consumption data. Results: The prevalence of use in particular for antithrombotic agents (B01) and cardiovascular drugs (C) increases significantly by 4 to 6 times for diabetic users compared to the GP, whereas the increase for analgesics (N02), psycoleptics, and psychoanaleptics (N06) was somewhat less (2–3 times). The five most used PGx drugs, both in the GP and among persons with diabetes, were pantoprazole, simvastatin, atorvastatin, metoprolol, and tramadol. The prevalence of use for persons with diabetes compared to the GP (prevalence ratio) increased by an average factor of 2.9 for all PGx drugs measured. In addition, the prevalence of use of combinations of PGx drugs was 4.6 times higher for persons with diabetes compared to GP. In conclusion, the findings of this study clearly show that a large fraction of persons with diabetes are exposed to drugs or drug combinations for which there exist PGx-based dosing guidelines related to CYP2D6, CYP2C19, and SLCO1B1. This further supports the notion of accessing and accounting for not only DDI but also DGI and phenoconversion in clinical decision-making, with a particular focus on persons with diabetes.

Applications for pharmacogenomics in pharmacy practice: A scoping review

BACKGROUND

Pharmacogenomics (PGx) can provide valuable pharmacokinetic and pharmacodynamic information for the pharmacist's assessment of drug therapy, especially within medication therapy management (MTM) services. However, no review has comprehensively mapped the pharmacists' use of PGx in practice-based research. Doing so would allow future researchers, practitioners, and policy-makers to identify the ideal populations and settings for PGx implementation within the pharmacy.

OBJECTIVE

The purpose of this review is to identify the evidence to date of PGx use in pharmacy practice.

METHODS

A scoping review was conducted to find all studied non-oncologic pharmacy practices incorporating PGx testing. Search terms were applied to 5 databases and relevant journals. Characteristics of patients, pharmacy settings, genetic tests, and outcomes were summarized to determine models most likely to benefit patients.

RESULTS

The search identified 43 studies on the use of PGx by pharmacists published between 2007 and 2020. CYP2C19 testing with antiplatelets was the most studied model, found in both community and institutional settings. It also was the most actionable test: approximately 30% of patients have polymorphisms indicating a need for alternative antiplatelets, and identifying these patients can reduce morbidity and mortality by more than 50%. As technology shifts, broader studies using multi-gene panel tests within MTM demonstrate an approximate 50% decrease in emergency visits and hospitalizations in elderly polypharmacy patients. Clinical benefit or drug-gene interactions are also found in other cardiovascular, psychiatric, analgesic, and gastrointestinal indications. No evaluations of actual costs or of pharmacist prescribing within pharmacy-based PGx have been performed. Facilitators towards successful PGx implementation included pharmacist education, collaboration with other healthcare providers, and the use of clinical decision software.

CONCLUSIONS

Pharmacogenomic testing has demonstrated feasibility and improved medication outcomes in pharmacy practice, including in the community pharmacy. Further PGx research should be directed towards pharmacist prescribing, pharmacist education, and pharmacoeconomics.

In vitro study on the effect of leonurine hydrochloride on the enzyme activity of cytochrome P450 enzymes in human liver microsomes

Leonurine hydrochloride (LH) is derived from an ingredient of Leonurus japonicus Houtt which is widely used for diseases in women.The influence of LH on the activity of cytochrome P450 (CYPs) enzymes was investigated in this study.The effect of LH on CYPs enzyme activities were studied using the enzyme-selective substrates phenacetin (1A2), coumarin (2A6), diclofenac (2C9), S-mephenytoin (2C19), paclitaxel (2C8), dextromethorphan (2D6), chlorzoxazone (2E1) and testosterone (3A4). The IC₅₀ value was calculated to express the strength of inhibition. The inhibition of CYPs was fitted with competitive or non-competitive inhibition models and corresponding parameters were also obtained.LH exerted inhibitory effects on the activity of CYP1A2, 2D6, and 3A4 with the IC₅₀ values of 18.05, 15.13, and 20.09 μM, respectively. The obtained results showed that LH inhibited the activity of CYP1A2 and CYP2D6 via competitive manners (K_i = 8.667 μM and K_i = 7.805 μM, respectively), while LH attenuated the CYP3A4 activity via a non-competitive manner (K_i = 9.507 μM). Moreover, LH showed time-dependent inhibition on CYP3A4 with the K_I/K_inact value of 4.31/0.044 min^-1·μM^-1.The inhibition of CYP1A2, CYP2D6, and CYP3A4 by LH, demonstrated in vitro, indicated the potential herb-drug interaction. Therefore, pharmacokinetic interactions involving LH and CYP1A2 or CYP2D6 or CYP1A2 substrates are likely to occur.

Individualized Drugs' Selection by Evaluation of Drug Properties, Pharmacogenomics and Clinical Parameters: Performance of a Bioinformatic Tool Compared to a Clinically Established Counselling Process

Purpose

Inefficacy and safety concerns are main medications’ problems, especially in the case of poly-therapies, when drug–drug interactions may alter the expected drug disposition. Ongoing efforts are aimed to establish drug selection processes aimed to preemptive evaluation of a plethora of factors affecting patient’s specific drug response, including pharmacogenomic markers, in order to minimize prescription of improper medications. In previous years, we established at the University Hospital Sant’Andrea of Rome, Italy, a Precision Medicine Service based on a multi-disciplinary experts’ team. The team is in charge to produce a drug therapy counselling report, including pharmacogenomic, pharmacokinetic and pharmacodynamic considerations. In this study, we aimed to evaluate the performance of this established “manual” process of therapy selection with a novel bioinformatic tool, the Drug-PIN system.

Patients and Methods

A total of 200 patients diagnosed with Major Depressive Disorders or a depressive episode in Bipolar Disorder, with at least three previous failed treatments, who underwent pharmacogenomic profiling and therapy counselling in the Sant’Andrea Hospital from 2017 to 2020. The baseline poly-therapy of these patients was re-evaluated and optimized by Drug-PIN. Results of the Drug-PIN poly-therapy evaluation/optimization were compared with the results of the original poly-therapy evaluation/optimization by therapy counselling. To compare the results between the two processes, the risk associated with each poly-therapy was classified as low, moderate, or high.

Results

The number of baseline poly-therapies classified in low-, moderate- or high-risk did not change significantly between manual system or Drug-PIN system. As the counselling process, also the Drug-PIN system produces a significant decrease in the predicted treatment-associated risk.

Conclusion

Drug-PIN substantially replicates the output of the counselling process, allowing a substantial reduction in the time needed for therapy evaluation. Availability of an effective bioinformatic tool for proper drug selection is expected to exponentially increase the actuation of targeted therapy strategies.

Drug-drug-gene interactions as mediators of adverse drug reactions to diclofenac and statins: a case report and literature review

Concomitant treatment with drugs that inhibit drug metabolising enzymes and/or transporters, such as commonly prescribed statins and nonsteroidal anti-inflammatory drugs (NSAIDs), has been associated with prolonged drug exposure and increased risk of adverse drug reactions (ADRs) due to drug-drug interactions. The risk is further increased in patients with chronic diseases/comorbidities who are more susceptible because of their genetic setup or external factors. In that light, we present a case of a 46-year-old woman who had been experiencing acute renal and hepatic injury and myalgia over two years of concomitant treatment with diclofenac, atorvastatin, simvastatin/fenofibrate, and several other drugs, including pantoprazole and furosemide. Our pharmacogenomic findings supported the suspicion that ADRs, most notably the multi-organ toxicity experienced by our patient, may be owed to drug-drug-gene interactions and increased bioavailability of the prescribed drugs due to slower detoxification capacity and decreased hepatic and renal elimination. We also discuss the importance of CYP polymorphisms in the biotransformation of endogenous substrates such as arachidonic acid and their modulating role in pathophysiological processes. Yet even though the risks of ADRs related to the above mentioned drugs are substantially evidenced in literature, pre-emptive pharmacogenetic analysis has not yet found its way into common clinical practice.

Pharmacogenomic landscape of COVID-19 therapies from Indian population genomes

Aim: Numerous drugs are being widely prescribed for COVID-19 treatment without any direct evidence for the drug safety/efficacy in patients across diverse ethnic populations. Materials & methods: We analyzed whole genomes of 1029 Indian individuals (IndiGen) to understand the extent of drug–gene (pharmacogenetic), drug–drug and drug–drug–gene interactions associated with COVID-19 therapy in the Indian population. Results: We identified 30 clinically significant pharmacogenetic variants and 73 predicted deleterious pharmacogenetic variants. COVID-19-associated pharmacogenes were substantially overlapped with those of metabolic disorder therapeutics. CYP3A4, ABCB1 and ALB are the most shared pharmacogenes. Fifteen COVID-19 therapeutics were predicted as likely drug–drug interaction candidates when used with four CYP inhibitor drugs. Conclusion: Our findings provide actionable insights for future validation studies and improved clinical decisions for COVID-19 therapy in Indians.

4-O-galloylalbiflorin inhibits the activity of CYP3A, 2C9, and 2D in human liver microsomes

The effect of 4-O-galloylalbiflorin on the activity of cytochrome P450 enzymes (CYP450s) is an important factor that may induce drug-drug interaction.The effect of 4-O-galloylalbiflorin on the activity of CYP450s was evaluated in the presence of 0, 2.5, 5, 10, 25, 50, and 100 μM 4-O-galloylalbiflorin in pooled human liver microsomes. The inhibition model and corresponding parameters were assessed b fitting with Lineweaver-Burk plots. The time-dependent study was performed with the incubation time of 0, 5, 10, 15, and 30 min.4-O-galloylalbiflorin significantly inhibited the activity of CYP3A, 2C9, and 2 D in a concentration-dependent manner with the IC50 values of 8.2, 13, and 11 μM, respectively. The inhibition of CYP3A was found to be non-competitive and time-dependent with the Ki value of 4.0 μM and the KI/Kinact value of 2.2/0.030 (μM·min). The inhibition of CYP2C9 and 2 D was not affected by the incubation time but was found to be competitive with the Ki values of 6.7 and 6.6 μM, respectively.The inhibitory effect of 4-O-galloylalbiflorin on the activity of CYP3A, 2C9, and 2 D implying the potential drug-drug interaction between 4-O-galloylalbiflorin and the drugs metabolized by these CYP450s.

Effects of Genetic Polymorphism in CYP2D6, CYP2C19, and the Organic Cation Transporter OCT1 on Amitriptyline Pharmacokinetics in Healthy Volunteers and Depressive Disorder Patients

The tricyclic antidepressant amitriptyline is frequently prescribed but its use is limited by its narrow therapeutic range and large variation in pharmacokinetics. Apart from interindividual differences in the activity of the metabolising enzymes cytochrome P450 (CYP) 2D6 and 2C19, genetic polymorphism of the hepatic influx transporter organic cation transporter 1 (OCT1) could be contributing to interindividual variation in pharmacokinetics. Here, the impact of OCT1 genetic variation on the pharmacokinetics of amitriptyline and its active metabolite nortriptyline was studied in vitro as well as in healthy volunteers and in depressive disorder patients. Amitriptyline and nortriptyline were found to inhibit OCT1 in recombinant cells with IC₅₀ values of 28.6 and 40.4 µM. Thirty other antidepressant and neuroleptic drugs were also found to be moderate to strong OCT1 inhibitors with IC₅₀ values in the micromolar range. However, in 35 healthy volunteers, preselected for their OCT1 genotypes, who received a single dose of 25 mg amitriptyline, no significant effects on amitriptyline and nortriptyline pharmacokinetics could be attributed to OCT1 genetic polymorphism. In contrast, the strong impact of the CYP2D6 genotype on amitriptyline and nortriptyline pharmacokinetics and of the CYP2C19 genotype on nortriptyline was confirmed. In addition, acylcarnitine derivatives were measured as endogenous biomarkers for OCT1 activity. The mean plasma concentrations of isobutyrylcarnitine and 2-methylbutyrylcarnitine were higher in participants with two active OCT1 alleles compared to those with zero OCT1 activity, further supporting their role as endogenous in vivo biomarkers for OCT1 activity. A moderate reduction in plasma isobutyrylcarnitine concentrations occurred at the time points at which amitriptyline plasma concentrations were the highest. In a second, independent study sample of 50 patients who underwent amitriptyline therapy of 75 mg twice daily, a significant trend of increasing amitriptyline plasma concentrations with decreasing OCT1 activity was observed (p = 0.018), while nortriptyline plasma concentrations were unaffected by the OCT1 genotype. Altogether, this comprehensive study showed that OCT1 activity does not appear to be a major factor determining amitriptyline and nortriptyline pharmacokinetics and that hepatic uptake occurs mainly through other mechanisms.

Pharmacogenetic testing in psychiatry and neurology: an overview of reviews

Pharmacogenetic testing is available to healthcare professionals to guide drug selection and prevent adverse events. However, its implementation in the clinical practice of psychiatry/neurology still has barriers, mainly due to a lack of evidence. We conducted a literature search on Cochrane Library, Embase and Pubmed, from their inception to 18 June 2020. We included 16 published systematic reviews. The most studied drug categories were anticonvulsants and selective serotonin reuptake inhibitors associated with human leukocyte antigen and cytochrome P450 genes (HLA-A, HLA-B, CYP2C9, CYP2D6, CYP2C19), classified as critically low quality/low quality. There is a need for more robust studies with adequate design to assess the potential benefits of adopting pharmacogenetics in health systems and services.

Risk prediction of drug-drug interaction potential of phenytoin and miconazole topical formulations

The drug-drug interaction (DDI) risk of phenytoin with several topical formulations of miconazole is still unclear. The present investigation conducted in vitro-in vivo extrapolation to predict the potential risks. Our data indicated that miconazole potently inhibited phenytoin hydroxylation in both pooled human liver microsomes (HLMs) and recombinant cytochrome P450 2C9 (CYP2C9) with the K_i values of 125 ± 7 nM and 30 ± 2 nM, respectively. Quantitative prediction of DDI risk suggests that, beside intravenous administration or swallowed tablet, combination of phenytoin and miconazole high dose oral gel or buccal tablet may also result in a clinically significant increase of phenytoin AUC (>53%) by the inhibition of miconazole against phenytoin hydroxylation, consequently a higher frequency of adverse events, while the coadministration of miconazole vaginal formulation and phenytoin will be safe.

Different Pharmacokinetics of Tramadol, O-Demethyltramadol and N-Demethyltramadol in Postoperative Surgical Patients From Those Observed in Medical Patients

Background: Most studies examining tramadol metabolism have been carried out in non-surgical patients and with oral tramadol. The aim of this study was 1) to measure concentrations of tramadol, O-demethyltramadol (ODT), and N-demethyltramadol (NDT) in the surgical patients admitted to the intensive care unit (ICU) within the first 24 postoperative hours after intravenous application of tramadol, and 2) to examine the effect of systemic inflammation on tramadol metabolism and postoperative pain. Methods: A prospective observational study was carried out in the surgical ICU in the tertiary hospital. In the group of 47 subsequent patients undergoing major abdominal surgery, pre-operative blood samples were taken for CYP2D6 polymorphism analysis. Systemic inflammation was assessed based on laboratory and clinical indicators. All patients received 100 mg of tramadol intravenously every 6 h during the first postoperative day. Postoperative pain was assessed before and 30 min after tramadol injections. Tramadol, ODT, and NDT concentrations were determined by high-performance liquid chromatography. Results: CYP2D6 analysis revealed 2 poor (PM), 22 intermediate (IM), 22 extensive (EM), and 1 ultrafast metabolizer. After a dose of 100 mg of tramadol, t1/2 of 4.8 (3.2-7.6) h was observed. There were no differences in tramadol concentration among metabolic phenotypes. The area under the concentration-time curve at the first dose interval (AUC1-6) of tramadol was 1,200 (917.9-1944.4) μg ×h ×L-1. NDT concentrations in UM were below the limit of quantification until the second dose of tramadol was administrated, while PM had higher NDT concentrations compared to EM and IM. ODT concentrations were higher in EM, compared to IM and PM. ODT AUC1-6 was 229.6 (137.7-326.2) μg ×h ×L-1 and 95.5 (49.1-204.3) μg ×h ×L-1 in EM and IM, respectively (p = 0.004). Preoperative cholinesterase activity (ChE) of ≤4244 U L-1 was a cut-off value for a prediction of systemic inflammation in an early postoperative period. NDT AUC1-6 were significantly higher in patients with low ChE compared with normal ChE patients (p = 0.006). Pain measurements have confirmed that sufficient pain control was achieved in all patients after the second tramadol dose, except in the PM. Conclusions: CYP2D6 polymorphism is a major factor in O-demethylation, while systemic inflammation accompanied by low ChE has an important role in the N-demethylation of tramadol in postoperative patients. Concentrations of tramadol, ODT, and NDT are lower in surgical patients than previously reported in non-surgical patients. Clinical Trial Registration: ClinicalTrials.gov, NCT04004481.

Trichostatin A sensitizes hepatoma cells to Taxol more than 5-Aza-dC and dexamethasone

OBJECTIVES

This work was designed to compare the sensitizing effects of epigenetic modifiers on cancer cells vs. that of glucocorticoids. Also, to evaluate their effects on genes involved in epigenetic changes and drug metabolism.

METHODS

Hepatoma cells (HepG2) were treated with the anticancer drug (Taxol), with a histone deacetylase inhibitor (Trichostatin A [TSA]), DNA methyltransferase inhibitor (5-Aza-dC) or dexamethasone (DEX). Cytotoxicity was assessed by MTT assay and the apoptosis was determined by Annexin V-FITC. The expression levels of HDAC1, HDAC3, Dnmt1, Dnmt3α, CYP1A2, CYP3A4, CYP2B6, CYP2C19 and CYP2D6 were monitored by qRT-PCR.

RESULTS

TSA, synergistically enhanced cells sensitivity with the anticancer effect of Taxol more than 5-Aza-dC and DEX. This was evidenced by the relative decrease in IC₅₀ in cells cotreated with Taxol + TSA, Taxol + 5-Aza-dC or Taxol + DEX. Apoptosis was induced in 51.2, 16.9 and 41.3% of cells, respectively. In presence of Taxol, TSA induced four-fold increase in the expression of HDAC1 and downregulated Dnmt1&3α genes. CYP2D6 demonstrated progressive expression (up to 28-fold) with the increasing number of drugs. Moreover, the isoform overexpressed in cells treated with TSA + Taxol > DEX + Taxol > 5-Aza-dC + Taxol (6.4, 4.6 and 2.99, respectively). The investigated genes were clustered in two distinct subsets, where no coregulation was observed between HDAC1 and HDAC3. However, tight pairwise correlation-based cluster was seen between (CYP3A4/Dnmt3α and CYP2D6/CYP2C19).

CONCLUSIONS

The data reflects the sensitizing effect of acetylation modification by TSA on the responsiveness of hepatoma cells to anticancer therapy. The effect of histone deacetylase inhibition was more than hypomethylation and glucocorticoid effects. TSA exerts its role through its modulatory role on epigenetics and drugs metabolizing genes. Other modifiers (5-Aza-dC and DEX), however may adopt different mechanisms.

Trichostatin A sensitizes hepatoma cells to Taxol more than 5-Aza-dC and dexamethasone

OBJECTIVES

This work was designed to compare the sensitizing effects of epigenetic modifiers on cancer cells vs. that of glucocorticoids. Also, to evaluate their effects on genes involved in epigenetic changes and drug metabolism.

METHODS

Hepatoma cells (HepG2) were treated with the anticancer drug (Taxol), with a histone deacetylase inhibitor (Trichostatin A [TSA]), DNA methyltransferase inhibitor (5-Aza-dC) or dexamethasone (DEX). Cytotoxicity was assessed by MTT assay and the apoptosis was determined by Annexin V-FITC. The expression levels of HDAC1, HDAC3, Dnmt1, Dnmt3α, CYP1A2, CYP3A4, CYP2B6, CYP2C19 and CYP2D6 were monitored by qRT-PCR.

RESULTS

TSA, synergistically enhanced cells sensitivity with the anticancer effect of Taxol more than 5-Aza-dC and DEX. This was evidenced by the relative decrease in IC50 in cells cotreated with Taxol + TSA, Taxol + 5-Aza-dC or Taxol + DEX. Apoptosis was induced in 51.2, 16.9 and 41.3% of cells, respectively. In presence of Taxol, TSA induced four-fold increase in the expression of HDAC1 and downregulated Dnmt1&3α genes. CYP2D6 demonstrated progressive expression (up to 28-fold) with the increasing number of drugs. Moreover, the isoform overexpressed in cells treated with TSA + Taxol > DEX + Taxol > 5-Aza-dC + Taxol (6.4, 4.6 and 2.99, respectively). The investigated genes were clustered in two distinct subsets, where no coregulation was observed between HDAC1 and HDAC3. However, tight pairwise correlation-based cluster was seen between (CYP3A4/Dnmt3α and CYP2D6/CYP2C19).

CONCLUSIONS

The data reflects the sensitizing effect of acetylation modification by TSA on the responsiveness of hepatoma cells to anticancer therapy. The effect of histone deacetylase inhibition was more than hypomethylation and glucocorticoid effects. TSA exerts its role through its modulatory role on epigenetics and drugs metabolizing genes. Other modifiers (5-Aza-dC and DEX), however may adopt different mechanisms.

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.