Influence of cytochrome P450 polymorphisms on drug therapies: pharmacogenetic, pharmacoepigenetic and clinical aspects

The use of attention-deficit hyperactivity disorder medications in cardiac disease

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder with onset usually in childhood characterized by inattention, impulsivity, and hyperactivity causing a functional impairment. Untreated ADHD, or treatment delay is associated with adverse outcomes and poor quality of life. Although conservative management strategies such as behavioral and psychological interventions are important, pharmacological treatment has a strong evidence base with improved outcomes. ADHD medications are broadly divided into stimulant and non-stimulant medications. Stimulant medications are generally more effective than non-stimulants. Cardiovascular safety of ADHD medication has been a matter of debate for decades. Treatment guidelines advise the careful consideration of risks and benefits in people with cardiovascular diseases such as congenital heart disease or cardiomyopathy. Although stimulants can increase systemic blood pressure and heart rate, no significant associations were found between their use and serious cardiovascular events. Concerns regarding QT effects and attendant sudden cardiac death risks deter clinicians from initiating much-needed ADHD medications in patients with heart disease. This overly cautious approach is potentially depriving low-risk individuals from significant benefits associated with timely ADHD drug treatment. This review discusses the cardiovascular risks reportedly associated with ADHD medications, the evidence base for their safe usage in persons with established cardiovascular disease, and highlights future research directions.

An Investigation of O-Demethyl Tramadol/Tramadol Ratio for Cytochrome P450 2D6 Phenotyping: The CYTRAM Study

Cytochrome P450 2D6 (CYP2D6) gene polymorphisms influence the exposure to tramadol (T) and its pharmacologically active metabolite, O-demethyl tramadol (O-dT). Tramadol has been considered as a candidate probe drug for CYP2D6 phenotyping. The objective of the CYTRAM study was to investigate the value of plasma O-dT/T ratio for CYP2D6 phenotyping. European adult patients who received IV tramadol after surgery were included. CYP2D6 genotyping was performed and subjects were classified as extensive (EM), intermediate (IM), poor (PM), or ultra-rapid (UM) CYP2D6 metabolizers. Plasma concentrations of tramadol and O-dT were determined at 24 h and 48 h. The relationship between O-dT/T ratio and CYP2D6 phenotype was examined in both a learning and a validation group. Genotype data were obtained in 301 patients, including 23 PM (8%), 117 IM (39%), 154 EM (51%), and 7 UM (2%). Tramadol trough concentrations at 24 h were available in 297 patients. Mean value of O-dT/T ratio was significantly lower in PM than in non-PM individuals (0.061 ± 0.031 versus 0.178 ± 0.09, p < 0.01). However, large overlap was observed in the distributions of O-dT/T ratio between groups. Statistical models based on O-dT/T ratio failed to identify CYP2D6 phenotype with acceptable sensitivity and specificity. Those results suggest that tramadol is not an adequate probe drug for CYP2D6 phenotyping.

Therapeutic drug monitoring and safety evaluation of voriconazole in the treatment of pulmonary fungal diseases

Aims:

The gene polymorphism of voriconazole metabolism–related liver enzyme is notable in East Asia population. It casts a significant influence on the rational use of voriconazole. We conducted this study to investigate the relationship between steady-state voriconazole trough concentration (C_trough) and adverse effects (AEs), especially hepatotoxicity.

Methods:

We conducted a real-world study in the Jinling Hospital from January 2015 to June 2020. A total of 140 patients receiving voriconazole were enrolled in this study. The determination and scoring of voriconazole-associated hepatotoxicity were performed according to the Roussel Uclaf Causality Assessment Method scoring scale and the severity of hepatotoxicity was graded according to the Common Terminology Criteria for Adverse Events (CTCAE).

Results:

Elevated steady-state voriconazole C_trough with concomitant AEs are the most common reason for dose adjustments during treatment. Compared with the group without any AEs, voriconazole C_trough was significantly higher in the hepatotoxicity and neurotoxicity groups, and the incidence of both events showed an overall increasing trend with increasing voriconazole C_trough. Hepatotoxicity occurred in 66.7% of patients within 7 days of the first dose of voriconazole and 94.4% within 15 days of the dose. Steady-state voriconazole C_trough >3.61 mg/l was associated with an increased incidence of hepatotoxicity (area under the curve = 0.645, p = 0.047). Logistic regression analysis showed that timely voriconazole dose adjustment was a predictor of attenuated hepatotoxicity after adjustment for confounders, but hepatotoxicity was not associated with voriconazole C_trough measured at a single time point.

Conclusion:

Hepatotoxicity and neurotoxicity correlate with voriconazole C_trough, and dose reduction in patients with elevated steady-state voriconazole C_trough may prevent hepatotoxicity. In patients with early occurrence of hepatotoxicity, initial therapeutic drug monitoring (TDM) might predict the risk of hepatotoxicity. Follow-up TDM may be necessary to predict late onset hepatotoxicity.

Plain Language Summary

Safety of voriconazole for the treatment of pulmonary fungal diseases

Introduction: Several studies have suggested an association between the concentration of voriconazole in the blood and liver damage, but the evidence is weak. This study aimed to investigate relationships between voriconazole drug concentration and side effects and to analyze the factors affecting liver damage caused by voriconazole.

Methods: We conducted a study at the Jinling Hospital from January 2015 to June 2020, in which a total of 140 patients were finally enrolled.

Results: Voriconazole doses were adjusted in 44 patients due to abnormal voriconazole drug concentration or side effects, 32 patients reduced the dose and 8 patients increased the dose. An elevated liver enzyme level was the most common cause for dose adjustment. After the first dose adjustment, most patients achieved the target drug concentration. A total of 18 patients were determined as probable or highly probable to have drug-induced liver injury from voriconazole. Voriconazole drug concentration was significantly higher in the liver damage and nervous system damage groups as compared with the group without any side effects, and most liver damage events occurred within 14 days of the first dose. Voriconazole drug concentration >3.61 mg/l was associated with an increased incidence of liver damage.

Conclusion: In this study, approximately one-third of patients with pulmonary fungal disease needed to adjust their dose after the standard dose of voriconazole treatment. The incidence of liver damage and nervous system damage showed an overall increasing trend with increasing voriconazole baseline concentrations. Initial therapeutic drug monitoring may be predictive of liver damage. Follow-up monitoring of liver enzymes may be needed.

Ebola virus infection induces a delayed type I IFN response in bystander cells and the shutdown of key liver genes in human iPSC-derived hepatocytes

Liver damage and an exacerbated inflammatory response are hallmarks of Ebola virus (EBOV) infection. Little is known about the intrinsic response to infection in human hepatocytes and their contribution to inflammation. Here, we present an induced pluripotent stem cell (iPSC)-derived hepatocyte-like cell (HLC) platform to define the hepato-intrinsic response to EBOV infection. We used this platform to show robust EBOV infection, with characteristic ultrastructural changes and evidence for viral replication. Transcriptomics analysis revealed a delayed response with minimal early transcriptomic changes, followed by a general downregulation of hepatic function and upregulation of interferon signaling, providing a potential mechanism by which hepatocytes participate in disease severity and liver damage. Using RNA-fluorescence in situ hybridization (FISH), we showed that IFNB1 and CXCL10 were mainly expressed in non-infected bystander cells. We did not observe an inflammatory signature during infection. In conclusion, iPSC-HLCs are an immune competent platform to study responses to EBOV infection.

A comprehensive analysis of six forms of cytochrome P450 2C (CYP2C) in pigs

Pigs are an important species used in drug metabolism studies; however, the cytochromes P450 (P450s or CYPs) have not been fully investigated in pigs.In this study, pig CYP2C32, CYP2C33, CYP2C34, CYP2C36, CYP2C42, and CYP2C49 cDNAs were isolated and found to contain open reading frames of 490 or 494 amino acids that shared 64-82% sequence identity with human CYP2C8/9/18/19.Pig CYP2C genes formed a gene cluster in a genomic region that corresponded to that of the human CYP2C cluster; an additional gene cluster was formed by pig CYP2C33a and CYP2C33b distant from the first cluster but located in the same chromosome.Among the tissues analysed, these pig CYP2C mRNAs were preferentially expressed in liver, small intestine, and/or kidney; pig CYP2C49, CYP2C32, CYP2C34, and CYP2C33 mRNAs were the most abundant CYP2C mRNAs in liver, jejunum, ileum, and kidney, respectively.Metabolic assays showed that pig CYP2C proteins (heterologously expressed in Escherichia coli) metabolised typical human CYP2C substrates diclofenac, warfarin, and/or omeprazole.The results suggest that these pig CYP2Cs are functional enzymes able to metabolise human CYP2C substrates in liver and small intestine, just as human CYP2Cs do.

The Role of Pharmacogenomics in Opioid Prescribing

Pharmacogenomics is increasingly important to guide objective, safe, and effective individualised prescribing. Personalised prescribing has revolutionised treatments in the past decade, allowing clinicians to maximise drug efficacy and minimise adverse effects based on a person’s genetic profile. Opioids, the gold standard for cancer pain relief, are among the commonest medications prescribed in palliative care practice. This narrative review examines the literature surrounding opioid pharmacogenomics and its applicability to the palliative care cancer population. There is currently limited intersection between the fields of palliative care and pharmacogenomics, but growing evidence presents a need to build linkages between the two disciplines. Pharmacogenomic evidence guiding opioid prescribing is currently available for codeine and tramadol, which relates to CYP2D6 gene variants. However, these medications are prescribed less commonly for pain in palliative care. Research is accelerating with other opioids, where oxycodone (CYP2D6) and methadone (CYP2B6, ABCB1) already have moderate evidence of an association in terms of drug metabolism and downstream analgesic response and side effects. OPRM1 and COMT are receiving increasing attention and have implications for all opioids, with changes in opioid dosage requirements observed but they have not yet been studied widely enough to be considered clinically actionable. Current evidence indicates that incorporation of pharmacogenomic testing into opioid prescribing practice should focus on the CYP2D6 gene and its actionable variants. Although opioid pharmacogenomic tests are not widely used in clinical practice, the progressively reducing costs and rapid turnover means greater accessibility and affordability to patients, and thus, clinicians will be increasingly asked to provide guidance in this area. The upsurge in pharmacogenomic research will likely discover more actionable gene variants to expand international guidelines to impact opioid prescribing. This rapidly expanding area requires consideration and monitoring by clinicians in order for key findings with clinical implications to be accessible, meaningfully interpretable and communicated.

A Novel hepatocellular carcinoma specific hypoxic related signature for predicting prognosis and therapeutic responses

Hypoxia is an important feature of the tumor microenvironment(TME) and is closely associated with cancer metastasis, immune evasion, and drug resistance. However, the precise role of hypoxia in hepatocellular carcinoma(HCC), as well as its influence on the TME, and drug sensitivity remains unclear. We found the excellent survival prediction value of Hypoxia_DEGs_Score model. In hypoxic HCC, somatic mutation, copy number variation, and DNA methylation were closely related to hypoxic changes and affected tumorigenesis, progression, metastasis, and drug resistance. In HCC, aggravated hypoxic stress was found to be accompanied by an immune exclusion phenotype and increased infiltration of immunosuppressive cells. In the validation cohort, patients with high Hypoxia_DEGs_Score were found to have worse immunotherapeutic outcomes and prognoses, and may benefit from drugs against cell cycle signaling pathways rather than those inhibiting the PI3K/mTOR pathway. Hypoxia_DEGs_Score has an excellent predictive capability of changes in the TME, the efficacy of immunotherapy, and the response of drugs. Therefore, Hypoxia_DEGs_Score can help develop personalized immunotherapy regimens and improve the prognosis of HCC patients.

CYP2C19 expression modulates affective functioning and hippocampal subiculum volume-a large single-center community-dwelling cohort study

Given controversial findings of reduced depressive symptom severity and increased hippocampus volume in CYP2C19 poor metabolizers, we sought to provide empirical evidence from a large-scale single-center longitudinal cohort in the community-dwelling adult population-Colaus|PsyCoLaus in Lausanne, Switzerland (n = 4152). We looked for CYP2C19 genotype-related behavioral and brain anatomy patterns using a comprehensive set of psychometry, water diffusion- and relaxometry-based magnetic resonance imaging (MRI) data (BrainLaus, n = 1187). Our statistical models tested for differential associations between poor metabolizer and other metabolizer status with imaging-derived indices of brain volume and tissue properties that explain individuals' current and lifetime mood characteristics. The observed association between CYP2C19 genotype and lifetime affective status showing higher functioning scores in poor metabolizers, was mainly driven by female participants (ß = 3.9, p = 0.010). There was no difference in total hippocampus volume between poor metabolizer and other metabolizer, though there was higher subiculum volume in the right hippocampus of poor metabolizers (ß = 0.03, p_FDRcorrected = 0.036). Our study supports the notion of association between mood phenotype and CYP2C19 genotype, however, finds no evidence for concomitant hippocampus volume differences, with the exception of the right subiculum.

Recognition of functional genetic polymorphism using ESE motif definition: a conservative evolutionary approach to CYP2D6/CYP2C19 gene variants

Although predicting the effects of variants near intron-exon boundaries is relatively straightforward, predicting the functional Exon Splicing Enhancers (ESEs) and the possible effects of variants within ESEs remains a challenge. Considering the essential role of CYP2D6/CYP2C19 genes in drug metabolism, we attempted to identify variants that are most likely to disrupt splicing through their effect on these ESEs. ESEs were predicted in these two genes using ESEfinder 3.0, incorporating a series of filters (increased threshold and evolutionary conservation). Finally, reported mutations were evaluated for their potential to disrupt splicing by affecting these ESEs. Initially, 169 and 243 ESEs were predicted for CYP2C19/CYP2D6, respectively. However, applying the filters, the number of predicted ESEs was reduced to 26 and 19 in CYP2C19/CYP2D6, respectively. Comparing prioritized predicted ESEs with known sequence variants in CYP2C19/CYP2D6 genes highlights 18 variations within conserved ESEs for each gene. We found good agreement in cases where such predictions could be compared to experimental evidence. In total, we prioritized a subset of mutational changes in CYP2C19/CYP2D6 genes that may affect the function of these genes and lead to altered drug responses. Clinical studies and functional analysis for investigating detailed functional consequences of the mentioned mutations and their phenotypic outcomes is mostly recommended.

Candidate Proficiency Test Chemicals to Address Industrial Chemical Applicability Domains for in vitro Human Cytochrome P450 Enzyme Induction

Cytochrome P450 (CYP) enzymes play a key role in the metabolism of both xenobiotics and endogenous chemicals, and the activity of some CYP isoforms are susceptible to induction and/or inhibition by certain chemicals. As CYP induction/inhibition can bring about significant alterations in the level of in vivo exposure to CYP substrates and metabolites, CYP induction/inhibition data is needed for regulatory chemical toxicity hazard assessment. On the basis of available human in vivo pharmaceutical data, a draft Organisation for Economic Co-operation and Development Test Guideline (TG) for an in vitro CYP HepaRG test method that is capable of detecting the induction of four human CYPs (CYP1A1/1A2, 2B6, and 3A4), has been developed and validated for a set of pharmaceutical proficiency chemicals. However to support TG adoption, further validation data was requested to demonstrate the ability of the test method to also accurately detect CYP induction mediated by industrial and pesticidal chemicals, together with an indication on regulatory uses of the test method. As part of "GOLIATH", a European Union Horizon-2020 funded research project on metabolic disrupting chemical testing approaches, work is underway to generate supplemental validated data for an additional set of chemicals with sufficient diversity to allow for the approval of the guideline. Here we report on the process of proficiency chemical selection based on a targeted literature review, the selection criteria and considerations required for acceptance of proficiency chemical selection for OECD TG development (i.e. structural diversity, range of activity, relevant chemical sectors, global restrictions etc). The following 13 proposed proficiency chemicals were reviewed and selected as a suitable set for use in the additional validation experiments: tebuconazole, benfuracarb, atrazine, cypermethrin, chlorpyrifos, perfluorooctanoic acid, bisphenol A, N,N-diethyl-m-toluamide, benzo-[a]-pyrene, fludioxonil, malathion, triclosan, and caffeine. Illustrations of applications of the test method in relation to endocrine disruption and non-genotoxic carcinogenicity are provided.

The crucial role of epigenetic regulation in breast cancer anti-estrogen resistance: Current findings and future perspectives

Breast cancer (BC) cell de-sensitization to Tamoxifen (TAM) or other selective estrogen receptor (ER) modulators (SERM) is a complex process associated with BC heterogeneity and the transformation of ER signalling. The most influential resistance-related mechanisms include modifications in ER expression and gene regulation patterns. During TAM/SERM treatment, epigenetic mechanisms can effectively silence ER expression and facilitate the development of endocrine resistance. ER status is efficiently regulated by specific epigenetic tools including hypermethylation of CpG islands within ER promoters, increased histone deacetylase activity in the ER promoter, and/or translational repression by miRNAs. Over-methylation of the ER α gene (ESR1) promoter by DNA methyltransferases was associated with poor prognosis and indicated the development of resistance. Moreover, BC progression and spreading were marked by transformed chromatin remodelling, post-translational histone modifications, and expression of specific miRNAs and/or long non-coding RNAs. Therefore, targeted inhibition of histone acetyltransferases (e.g. MYST3), deacetylases (e.g. HDAC1), and/or demethylases (e.g. lysine-specific demethylase LSD1) was shown to recover and increase BC sensitivity to anti-estrogens. Indicated as a powerful molecular instrument, the administration of epigenetic drugs can regain ER expression along with the activation of tumour suppressor genes, which can in turn prevent selection of resistant cells and cancer stem cell survival. This review examines recent advances in the epigenetic regulation of endocrine drug resistance and evaluates novel anti-resistance strategies. Underlying molecular mechanisms of epigenetic regulation will be discussed, emphasising the utilization of epigenetic enzymes and their inhibitors to re-program irresponsive BCs.

Cytochrome P450 enzymes and metabolism of drugs and neurotoxins within the mammalian brain

Cytochrome P450 enzymes (CYPs) that metabolize xenobiotics are expressed and active in the brain. These CYPs contribute to the metabolism of many centrally acting compounds, including clinically used drugs, drugs of abuse, and neurotoxins. Although CYP levels are lower in the brain than in the liver, they may influence central substrate and metabolite concentrations, which could alter resulting centrally-mediated responses to these compounds. Additionally, xenobiotic metabolizing CYPs are highly variable due to genetic polymorphisms and regulation by endogenous and xenobiotic molecules. In the brain, these CYPs are sensitive to xenobiotic induction. As a result, CYPs in the brain vary widely, including among humans, and this CYP variation may influence central metabolism and resulting response to centrally acting compounds. It has been demonstrated, using experimental manipulation of CYP activity in vivo selectively within the brain, that CYP metabolism in the brain alters central substrate and metabolite concentrations, as well as drug response and neurotoxic effects. This suggests that variability in xenobiotic metabolizing CYPs in the human brain may meaningfully contribute to individual differences in response to, and effects of, centrally acting drugs and neurotoxins. This chapter will provide an overview of CYP expression in the brain, endogenous- and xenobiotic-mediated CYP regulation, and the functional impact of CYP-mediated metabolism of drugs and neurotoxins in the brain, with a focus on experimental approaches in mice, rats, and non-human primates, and a discussion regarding the potential role of xenobiotic metabolizing CYPs in the human brain.

Mesembryanthemum tortuosum L. alkaloids modify anxiety-like behaviour in a zebrafish model

ETHNOPHARMACOLOGICAL RELEVANCE

Mesembryanthemum tortuosum L. (previously known as Sceletium tortuosum (L.) N.E. Br.) is indigenous to South Africa and traditionally used to alleviate anxiety, stress and depression. Mesembrine and its alkaloid analogues such as mesembrenone, mesembrenol and mesembranol have been identified as the key compounds responsible for the reported effects on the central nervous system.

AIM OF THE STUDY

To investigate M. tortuosum alkaloids for possible anxiolytic-like effects in the 5-dpf in vivo zebrafish model by assessing thigmotaxis and locomotor activity.

MATERIALS AND METHODS

Locomotor activity and reverse-thigmotaxis, recognised anxiety-related behaviours in 5-days post fertilization zebrafish larvae, were analysed under simulated stressful conditions of alternating light-dark challenges. Cheminformatics screening and molecular docking were also performed to rationalize the inhibitory activity of the alkaloids on the serotonin reuptake transporter, the accepted primary mechanism of action of selective serotonin reuptake inhibitors. Mesembrine has been reported to have inhibitory effects on serotonin reuptake, with consequential anti-depressant and anxiolytic effects.

RESULTS

All four alkaloids assessed decreased the anxiety-related behaviour of zebrafish larvae exposed to the light-dark challenge. Significant increases in the percentage of time spent in the central arena during the dark phase were also observed when larvae were exposed to the pure alkaloids (mesembrenone, mesembrenol, mesembrine and mesembrenol) compared to the control. However, mesembrenone and mesembranol demonstrated a greater anxiolytic-like effect than the other alkaloids. In addition to favourable pharmacokinetic and physicochemical properties revealed via in silico predictions, high-affinity interactions characterized the binding of the alkaloids with the serotonin transporter.

CONCLUSIONS

M. tortuosum alkaloids demonstrated an anxiolytic-like effect in zebrafish larvae providing evidence for its traditional and modern day use as an anxiolytic.

Multi-omics analysis identifies a CYP9K1 haplotype conferring pyrethroid resistance in the malaria vector Anopheles funestus in East Africa

Metabolic resistance to pyrethroids is a menace to the continued effectiveness of malaria vector controls. Its molecular basis is complex and varies geographically across Africa. Here, we used a multi‐omics approach, followed‐up with functional validation to show that a directionally selected haplotype of a cytochrome P450, CYP9K1 is a major driver of resistance in Anopheles funestus. A PoolSeq GWAS using mosquitoes alive and dead after permethrin exposure, from Malawi and Cameroon, detected candidate genomic regions, but lacked consistency across replicates. Targeted sequencing of candidate resistance genes detected several SNPs associated with known pyrethroid resistance QTLs. The most significant SNPs were in the cytochrome P450 CYP304B1 (Cameroon), CYP315A1 (Uganda) and the ABC transporter gene ABCG4 (Malawi). However, when comparing field resistant mosquitoes to laboratory susceptible, the pyrethroid resistance locus rp1 and SNPs around the ABC transporter ABCG4 were consistently significant, except for Uganda where SNPs in the P450 CYP9K1 was markedly significant. In vitro heterologous metabolism assays with recombinant CYP9K1 revealed that it metabolises type II pyrethroid (deltamethrin; 64% depletion) but not type I (permethrin; 0%), while moderately metabolising DDT (17%). CYP9K1 exhibited reduced genetic diversity in Uganda underlying an extensive selective sweep. Furthermore, a glycine to alanine (G454A) amino acid change in CYP9K1 was fixed in Ugandan mosquitoes but not in other An. funestus populations. This study sheds further light on the evolution of metabolic resistance in a major malaria vector by implicating more genes and variants that can be used to design field‐applicable markers to better track resistance Africa‐wide.

Pharmacogenomics for the efficacy and side effects of antihistamines

Antihistamines, especially H1 antihistamines, are widely used in the treatment of allergic diseases such as urticaria and allergic rhinitis, mainly for reversing elevated histamine and anti-allergic effects. Antihistamines are generally safe, but some patients experience adverse reactions, such as cardiotoxicity, central inhibition, and anticholinergic effects. There are also individual differences in antihistamine efficacy in clinical practice. The concept of individualized medicine has been deeply rooted in people's minds since it was put forward. Pharmacogenomics is the study of the role of inheritance in individual variations in drug response. In recent decades, pharmacogenomics has been developing rapidly, which provides new ideas for individualized medicine. Polymorphisms in the genes encoding metabolic enzymes, transporters, and target receptors have been shown to affect the efficacy of antihistamines. In addition, recent evidence suggests that gene polymorphisms influence urticaria susceptibility and antihistamine therapy. Here, we summarize current reports in this area, aiming to contribute to future research in antihistamines and clinical guidance for antihistamines use in individualized medicine.

In Silico and Experimental Investigation of the Biological Potential of Some Recently Developed Carprofen Derivatives

The efficient regioselective bromination and iodination of the nonsteroidal anti-inflammatory drug (NSAID) carprofen were achieved by using bromine and iodine monochloride in glacial acetic acid. The novel halogenated carprofen derivatives were functionalized at the carboxylic group by esterification. The regioselectivity of the halogenation reaction was evidenced by NMR spectroscopy and confirmed by X-ray analysis. The compounds were screened for their in vitro antibacterial activity against planktonic cells and also for their anti-biofilm effect, using Gram-positive bacteria (Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212) and Gram-negative bacteria (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853). The cytotoxic activity of the novel compounds was tested against HeLa cells. The pharmacokinetic and pharmacodynamic profiles of carprofen derivatives, as well as their toxicity, were established by in silico analyses.

Exploring the usefulness of plasma level determination and pharmacogenetics for patients treated with clozapine

Aims: The aims of the present study were to assess the variance of plasma clozapine (CLZ) levels and to identify the influence of sociodemographic and pharmacogenetic factors on it and to introduce these tools in a clinical setting. Patients & methods: CLZ concentration was measured and genetic variants of CLZ pharmacokinetic and pharmacodynamic factors were assessed in 23 patients with psychotic disorders. Results: A significant association between mean concentration/dose ratio (C/D) and smoking status, age and weight were found. There was a significant difference in mean plasma CLZ levels and gender. The rs762551 AA genotype in smokers had a significantly lower C/D. Conclusion: In addition to classical factors, monitoring of plasma concentrations together with pharmacogenetics led to greater individualization of treatment.

Untangling SNP Variations within CYP2D6 Gene in Croatian Roma

CYP2D6 is a highly polymorphic gene whose variations affect its enzyme activity. To assess whether the specific population history of Roma, characterized by constant migrations and endogamy, influenced the distribution of alleles and thus phenotypes, the CYP2D6 gene was sequenced using NGS (Next Generation Sequencing) method-targeted sequencing in three groups of Croatian Roma (N = 323) and results were compared to European and Asian populations. Identified single nucleotide polymorphisms (SNPs) were used to reconstruct haplotypes, which were translated into the star-allele nomenclature and later into phenotypes. A total of 43 polymorphic SNPs were identified. The three Roma groups differed significantly in the frequency of alleles of polymorphisms 6769 A > G, 6089 G > A, and 5264 A > G (p < 0.01), as well as in the prevalence of the five most represented star alleles: *1, *2, *4, *10, and *41 (p < 0.0001). Croatian Roma differ from the European and Asian populations in the accumulation of globally rare SNPs (6089 G > A, 4589 C > T, 4622 G > C, 7490 T > C). Our results also show that demographic history influences SNP variations in the Roma population. The three socio-culturally different Roma groups studied differ significantly in the distribution of star alleles, which confirms the importance of a separate study of different Roma groups.

Integration of liquid biopsy and pharmacogenomics for precision therapy of EGFR mutant and resistant lung cancers

The advent of molecular profiling has revolutionized the treatment of lung cancer by comprehensively delineating the genomic landscape of the epidermal growth factor receptor (EGFR) gene. Drug resistance caused by EGFR mutations and genetic polymorphisms of drug metabolizing enzymes and transporters impedes effective treatment of EGFR mutant and resistant lung cancer. This review appraises current literature, opportunities, and challenges associated with liquid biopsy and pharmacogenomic (PGx) testing as precision therapy tools in the management of EGFR mutant and resistant lung cancers. Liquid biopsy could play a potential role in selection of precise tyrosine kinase inhibitor (TKI) therapies during different phases of lung cancer treatment. This selection will be based on the driver EGFR mutational status, as well as monitoring the development of potential EGFR mutations arising during or after TKIs treatment, since some of these new mutations may be druggable targets for alternative TKIs. Several studies have identified the utility of liquid biopsy in the identification of EGFR driver and acquired resistance with good sensitivities for various blood-based biomarkers. With a plethora of sequencing technologies and platforms available currently, further evaluations using randomized controlled trials (RCTs) in multicentric, multiethnic and larger patient cohorts could enable optimization of liquid-based assays for the detection of EGFR mutations, and support testing of CYP450 enzymes and drug transporter polymorphisms to guide precise dosing of EGFR TKIs.

CYP450 2D6 and 2C19 genotypes in ADHD: not related with treatment resistance but with over-representation of 2C19 ultra-metabolizers

OBJECTIVES

Cytochrome P450 (CYP450) is a major enzyme system involved in drug metabolism as well as regulation of brain function. Although individual variability in CYP enzymes have been studied in terms of personality traits and treatment effects, no study up to now evaluated CYP polymorphisms in children with attention deficit/hyperactivity disorder (ADHD). We aimed to define the genetic profiles of CYP2D6 and CYP2C19 relevant alleles in children with ADHD according to treatment status and compare the frequencies according to past results.

METHODS

Three hundred and seventeen patients with ADHD-Combined Presentation were enrolled; symptom severity was evaluated by parents and clinicians while adverse effects of previous treatments were evaluated with parent and child reports. Reverse blotting on strip assays was used for genotyping and descriptive and bivariate analyses were conducted. A p-value was set at 0.05 (two-tailed).

RESULTS

Children were divided into treatment-naïve (n=194, 61.2%) and treatment-resistant (n=123, 38.8%) groups. Within the whole sample PM, EM and UM status according to 2D6 were 3.8% (n=12), 94.3% (n=299) and 21.9% (n=6); respectively. PM, IM, EM and UM status according to 2C19 were 2.5% (n=8), 19.8% (n=63), 48.6% (n=154) and 29.0% (n=92), respectively. No relationship with treatment resistance, comorbidity or gender could be found. Importantly, CYP2C19 UMs were significantly more frequent in ADHD patients compared to previous studies in the general population.

CONCLUSIONS

CYPs may be a rewarding avenue of research to elucidate the etiology and treatment of patients with ADHD.

Clinical pharmacogenetic analysis in 5,001 individuals with diagnostic Exome Sequencing data

Exome sequencing is utilized in routine clinical genetic diagnosis. The technical robustness of repurposing large-scale next-generation sequencing data for pharmacogenetics has been demonstrated, supporting the implementation of preemptive pharmacogenetic strategies based on adding clinical pharmacogenetic interpretation to exomes. However, a comprehensive study analyzing all actionable pharmacogenetic alleles contained in international guidelines and applied to diagnostic exome data has not been performed. Here, we carried out a systematic analysis based on 5001 Spanish or Latin American individuals with diagnostic exome data, either Whole Exome Sequencing (80%), or the so-called Clinical Exome Sequencing (20%) (60 Mb and 17 Mb, respectively), to provide with global and gene-specific clinical pharmacogenetic utility data. 788 pharmacogenetic alleles, distributed through 19 genes included in Clinical Pharmacogenetics Implementation Consortium guidelines were analyzed. We established that Whole Exome and Clinical Exome Sequencing performed similarly, and 280 alleles in 11 genes (CACNA1S, CYP2B6, CYP2C9, CYP4F2, DPYD, G6PD, NUDT15, RYR1, SLCO1B1, TPMT, and UGT1A1) could be used to inform of pharmacogenetic phenotypes that change drug prescription. Each individual carried in average 2.2 alleles and overall 95% (n = 4646) of the cohort could be informed of at least one actionable pharmacogenetic phenotype. Differences in variant allele frequency were observed among the populations studied and the corresponding gnomAD population for 7.9% of the variants. In addition, in the 11 selected genes we uncovered 197 novel variants, among which 27 were loss-of-function. In conclusion, we provide with the landscape of actionable pharmacogenetic information contained in diagnostic exomes, that can be used preemptively in the clinics.

In vitro biotransformation of tris(1,3-dichloro-2-propyl) phosphate and triphenyl phosphate by mouse liver microsomes: Kinetics and key CYP isoforms

As the result of the phase-out on polybrominated diphenyl ethers, organophosphate flame retardants (OPFRs) were widely used as substitutes in the world. Previous studies found that OPFRs were frequently detected in environmental, biological, and human samples. Considering their adverse effects, the absorption, bioaccumulation, metabolism and internal exposure processes of OPFRs attracted more attentions recently, especially for aryl-OPFR and Cl-OPFRs. In the present study, the biotransformation, metabolic kinetics and related CYP450 isoforms of typical Cl-OPFR (tris(1,3-dichloro-2-propyl) phosphate: TDCPP) and aryl-OPFR (triphenyl phosphate: TPhP) were studied in vitro by mouse liver microsomes. Metabolomic analysis revealed that TDCPP may be easier to bio-accumulate in organisms than TPhP, which can be explained by their metabolic rates and half-life values (TDCPP: t_1/2 = 1.8083 h; TPhP: t_1/2 = 0.1531 h). CYP2E1, CYP2D6, CYP1A2 and CYP2C19 were suggested to be the specific enzymes for the biotransformation of TDCPP via associated inhibition assay. CYP2E1 was the primary CYP450 isoform of metabolism in vitro for TPhP. These findings may provide new insights for the potential mechanism of hepatotoxicity in mammals induced by OPFRs and the detoxification process of OPFRs in hepatocytes.

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.

Genetic Polymorphisms of Very Important Pharmacogene Variants in the Blang Population from Yunnan Province in China

Background

We aimed to enrich the pharmacogenomic information of a Blang population (BP) from Yunnan Province in China.

Methods

We genotyped 55 very important pharmacogene (VIP) variants from the PharmGKB database and compared their genotype distribution (GD) in a BP with that of 26 populations by the χ² test. The minor allele frequency (MAF) distribution of seven significantly different single-nucleotide polymorphisms (SNPs) was conducted to compare the difference between the BP and 26 other populations.

Results

Compared with the GD of 55 loci in the BP, among 26 studied populations, GWD, YRI, GIH, ESN, MSL, TSI, PJL, ACB, FIN and IBS were the top-10 populations, which showed a significantly different GD >35 loci. CHB, JPT, CDX, CHS, and KHV populations had a significantly different GD <20 loci. A GD difference of 27–34 loci was found between the BP and 11 populations (LWK, CEU, ITU, STU, PUR, CLM, GBR, ASW, BEB, MXL and PEL). The GD of five loci (rs750155 (SULT1A1), rs4291 (ACE), rs1051298 (SLC19A1), rs1131596 (SLC19A1) and rs1051296 (SLC19A1)) were the most significantly different in the BP as compared with that of the other 26 populations. The genotype frequency of rs1800764 (ACE) and rs1065852 (CYP2D6) was different in all populations except for PEL and LWK, respectively. MAFs of rs1065852 (CYP2D6) and rs750155 (SULT1A1) showed the largest fluctuation between the BP and SAS, EUR, AFR and AMR populations.

Conclusion

Our data can provide theoretical guidance for safe and efficacious personalized drug use in the Blang population.

Effects of CYP2D6 Genetic Polymorphism and Drug Interaction on the Metabolism of Dacomitinib

We aim to study the effects of CYP2D6 variants and drug-drug interaction on the metabolism of dacomitinib. CYP2D6 variants were incubated with 25-1000 μM dacomitinib for 40 min at 37 °C, and the reaction was terminated by cooling to -80 °C immediately. For an in vivo experiment, 18 male Sprague-Dawley rats were randomly divided into three groups (n = 6): a single dose of 5 mg/kg dacomitinib (group A), a single dose of 6 mg/kg trazodone (group B), and a combined group (group C). Processed samples were analyzed by ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS.) The relative clearance of dacomitinib was reduced for most of the variants. Moreover, the inhibitory potency of classic CYP inhibitors on dacomitinib metabolism was significantly different among the main subtypes of CYP2D6. Interestingly, compared with gefitinib, even the same CYP2D6 variants showed significant differences in metabolic activity, suggesting that the activity of CYP2D6 has strong variability. In addition, the interaction between trazodone and dacomitinib was determined both in vitro and in vivo. When dacomitinib was given in combination with trazodone, the blood exposure to these two drugs increased remarkably. The mechanistic study revealed that the interaction followed the noncompetitive inhibition. We demonstrated that the activity of CYP2D6 variants to metabolize dacomitinib was significantly reduced. In combination with the CYP2D6 inhibitor, the degree of activity inhibition of different variants obviously differed. When trazodone and dacomitinib were used in combination, the body exposure to the two drugs increased significantly. This study provides data for the precise use of dacomitinib in clinical settings.

HiPSC-Derived Hepatocyte-like Cells Can Be Used as a Model for Transcriptomics-Based Study of Chemical Toxicity

Traditional toxicity risk assessment approaches have until recently focussed mainly on histochemical readouts for cell death. Modern toxicology methods attempt to deduce a mechanistic understanding of pathways involved in the development of toxicity, by using transcriptomics and other big data-driven methods such as high-content screening. Here, we used a recently described optimised method to differentiate human induced pluripotent stem cells (hiPSCs) to hepatocyte-like cells (HLCs), to assess their potential to classify hepatotoxic and non-hepatotoxic chemicals and their use in mechanistic toxicity studies. The iPSC-HLCs could accurately classify chemicals causing acute hepatocellular injury, and the transcriptomics data on treated HLCs obtained by TempO-Seq technology linked the cytotoxicity to cellular stress pathways, including oxidative stress and unfolded protein response (UPR). Induction of these stress pathways in response to amiodarone, diclofenac, and ibuprofen, was demonstrated to be concentration and time dependent. The transcriptomics data on diclofenac-treated HLCs were found to be more sensitive in detecting differentially expressed genes in response to treatment, as compared to existing datasets of other diclofenac-treated in vitro hepatocyte models. Hence iPSC-HLCs generated by transcription factor overexpression and in metabolically optimised medium appear suitable for chemical toxicity detection as well as mechanistic toxicity studies.

Studies on CYP3A activity during the menstrual cycle as measured by urinary 6β-hydroxycortisol/cortisol

The 6β-OH-cortisol/cortisol ratio (6β-OHC/C) in urine is an endogenous marker of drug-metabolizing enzyme cytochrome P450 3A (CYP3A). The primary aim of this single center, prospective, non-interventional cohort study, was to investigate the variability of 6β-OHC/C during the menstrual cycle. In addition, possible associations between the CYP3A activity and sex hormones, gut microbiota metabolite trimethylamine-N-Oxide (TMAO) and microRNA-27b, respectively, were investigated. Serum and urinary samples from healthy, regularly menstruating women followed for two menstrual cycles were analyzed. Twenty-six complete menstrual cycles including follicular, ovulatory, and luteal phase were defined based on hormone analyses in serum. 6β-OHC/C were analyzed in urine and sex hormones, TMAO and miRNA-27b were analyzed in serum at the same time points. 6β-OHC/C did not vary between the follicular, ovulatory, or luteal phases. There was a difference in the relative miRNA-27b expression between the follicular and ovulatory phase (p = .03). A significant association was found between 6β-OHC/C and progesterone during the follicular (p = .005) and ovulatory (p = .01) phases (n = 26 for each phase). In addition, a significant association was found between the ratio and TMAO during the ovulatory (p = .02) and luteal (p = .002) phases. 6β-OHC/C and gut microbiota TMAO were significantly associated (p = .003) when evaluating all values, for all phases (n = 78). Interestingly, the finding of an association between 6β-OHC/C in urine and levels of TMAO in serum suggest that gut microbiota may affect CYP3A activity.

Improving the transparency of meta-analyses with interactive web applications

Increased transparency in study design and analysis is one proposed solution to the perceived reproducibility crisis facing science. Systematic review and meta-analysis-through which individual studies on a specific association are ascertained, assessed for quality and quantitatively combined-is a critical process for building consensus in medical research. However, the conventional publication model creates static evidence summaries that force the quality assessment criteria and analytical choices of a small number of authors onto all stakeholders, some of whom will have different views on the quality assessment and key features of the analysis. This leads to discordant inferences from meta-analysis results and delayed arrival at consensus. We propose a shift to interactive meta-analysis, through which stakeholders can take control of the evidence synthesis using their own quality criteria and preferred analytic approach-including the option to incorporate prior information on the association in question-to reveal how their summary estimate differs from that reported by the original analysts. We demonstrate this concept using a web-based meta-analysis of the association between genetic variation in a key tamoxifen-metabolising enzyme and breast cancer recurrence in tamoxifen-treated women. We argue that interactive meta-analyses would speed consensus-building to the degree that they reveal invariance of inferences to different study selection and analysis criteria. On the other hand, when inferences are found to differ substantially as a function of these choices, the disparities highlight where future research resources should be invested to resolve lingering sources of disagreement.

Use of Pharmacogenomics to Guide Proton Pump Inhibitor Therapy in Clinical Practice

Prescribing the right medication, at the right dose, to the right patient is the goal of every physician. Pharmacogenomic information is an emerging tool that can be used to deliver precision medicine. In this review, we discuss the pharmacogenomics of available PPIs, racial differences of CYP2C19 and how PPI pharmacogenomics affects the treatment of common gastrointestinal diseases. We also provide practical guidance on when to order pharmacogenomic testing, which test to order, and how to modify treatment based on published guidelines.

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.

Cytochrome P450 Enzymes and Drug Metabolism in Humans

Human cytochrome P450 (CYP) enzymes, as membrane-bound hemoproteins, play important roles in the detoxification of drugs, cellular metabolism, and homeostasis. In humans, almost 80% of oxidative metabolism and approximately 50% of the overall elimination of common clinical drugs can be attributed to one or more of the various CYPs, from the CYP families 1–3. In addition to the basic metabolic effects for elimination, CYPs are also capable of affecting drug responses by influencing drug action, safety, bioavailability, and drug resistance through metabolism, in both metabolic organs and local sites of action. Structures of CYPs have recently provided new insights into both understanding the mechanisms of drug metabolism and exploiting CYPs as drug targets. Genetic polymorphisms and epigenetic changes in CYP genes and environmental factors may be responsible for interethnic and interindividual variations in the therapeutic efficacy of drugs. In this review, we summarize and highlight the structural knowledge about CYPs and the major CYPs in drug metabolism. Additionally, genetic and epigenetic factors, as well as several intrinsic and extrinsic factors that contribute to interindividual variation in drug response are also reviewed, to reveal the multifarious and important roles of CYP-mediated metabolism and elimination in drug therapy.

Pharmacogenetics and Forensic Toxicology: A New Step towards a Multidisciplinary Approach

Pharmacogenetics analyzes the individual behavior of DNA genes after the administration of a drug. Pharmacogenetic research has been implemented in recent years thanks to the improvement in genome sequencing techniques and molecular genetics. In addition to medical purposes, pharmacogenetics can constitute an important tool for clarifying the interpretation of toxicological data in post-mortem examinations, sometimes crucial for determining the cause and modality of death. The purpose of this systematic literature review is not only to raise awareness among the forensic community concerning pharmacogenetics, but also to provide a workflow for forensic toxicologists to follow in cases of unknown causes of death related to drug use/abuse. The scientific community is called on to work hard in order to supply evidence in forensic practice, demonstrating that this investigation could become an essential tool both in civil and forensic contexts. The following keywords were used for the search engine: (pharmacogenetics) AND (forensic toxicology); (pharmacogenetics) AND (post-mortem); (pharmacogenetics) AND (forensic science); and (pharmacogenetics) AND (autopsy). A total of 125 articles were collected. Of these, 29 articles were included in this systematic review. A total of 75% of the included studies were original articles (n = 21) and 25% were case reports (n = 7). A total of 78% (n = 22) of the studies involved deceased people for whom a complete autopsy was performed, while 22% (n = 6) involved people in good health who were given a drug with a subsequent pharmacogenetic study. The most studied drugs were opioids (codeine, morphine, and methadone), followed by antidepressants (tricyclic antidepressants and venlafaxine). Furthermore, all studies highlighted the importance of a pharmacogenetics study in drug-related deaths, especially in cases of non-overdose of drugs of abuse. This study highlights the importance of forensic pharmacogenetics, a field of toxicology still not fully understood, which is of great help in cases of sudden death, deaths from overdose, deaths after the administration of a drug, and also in cases of complaint of medical malpractice.

The Influence of CYP2D6 and CYP2C19 Genetic Variation on Diabetes Mellitus Risk in People Taking Antidepressants and Antipsychotics

CYP2D6 and CYP2C19 enzymes are essential in the metabolism of antidepressants and antipsychotics. Genetic variation in these genes may increase risk of adverse drug reactions. Antidepressants and antipsychotics have previously been associated with risk of diabetes. We examined whether individual genetic differences in CYP2D6 and CYP2C19 contribute to these effects. We identified 31,579 individuals taking antidepressants and 2699 taking antipsychotics within UK Biobank. Participants were classified as poor, intermediate, or normal metabolizers of CYP2D6, and as poor, intermediate, normal, rapid, or ultra-rapid metabolizers of CYP2C19. Risk of diabetes mellitus represented by HbA1c level was examined in relation to the metabolic phenotypes. CYP2D6 poor metabolizers taking paroxetine had higher Hb1Ac than normal metabolizers (mean difference: 2.29 mmol/mol; p < 0.001). Among participants with diabetes who were taking venlafaxine, CYP2D6 poor metabolizers had higher HbA1c levels compared to normal metabolizers (mean differences: 10.15 mmol/mol; p < 0.001. Among participants with diabetes who were taking fluoxetine, CYP2D6 intermediate metabolizers and decreased HbA1c, compared to normal metabolizers (mean difference -7.74 mmol/mol; p = 0.017). We did not observe any relationship between CYP2D6 or CYP2C19 metabolic status and HbA1c levels in participants taking antipsychotic medication. Our results indicate that the impact of genetic variation in CYP2D6 differs depending on diabetes status. Although our findings support existing clinical guidelines, further research is essential to inform pharmacogenetic testing for people taking antidepressants and antipsychotics.

A Quantitative Approach to the Prediction of Drug-Drug Interactions Mediated by Cytochrome P450 2C8 Inhibition

BACKGROUND

Ohno and Colleagues proposed an approach for predicting drug-drug interactions (DDIs) mediated by cytochrome P450 (CYP) 3A4 based on the use of the ratio of the inhibited to non-inhibited area under the plasma concentration time curve (AUC) of substrates to estimate the fraction of the dose metabolized via CYP3A4 (contribution ratio, CR) and the in vivo inhibitory potency of a perpetrator (inhibition ratio, IR). This study evaluated the performance of this approach on DDIs mediated by CYP2C8 inhibitors.

RESEARCH DESIGN AND METHODS

Initial estimates of CR and IR of CYP2C8 substrates and inhibitors were calculated for 33 DDI in vivo studies. The approach was externally validated with 17 additional studies. Bayesian orthogonal regression was used to refine the estimates of the parameters. Assessment of prediction success was conducted by plotting observed versus predicted AUC ratios.

RESULTS

Final estimates of CRs and IRs were obtained for 19 CYP2C8 substrates and 23 inhibitors, respectively. The method demonstrated good predictive capacity, with only two values outside of the prespecified limits.

CONCLUSIONS

The approach may help to adapt dose regimens for CYP2C8 substrates when given in combination with CYP2C8 inhibitors and to map the potential DDIs of new molecular entities.

[Current Challenges in Pharmacotherapy]

Analysis of preoperative medication is used to assess the benefit and risk associated with continuing or discontinuing medication before and during surgery. Identifying adverse drug reactions and assessing its risks often leads to uncertainty. Typical challenges are medication underuse, but also overuse occurs and is often more difficult to recognize, especially in the context of drug interactions and individual patient characteristics.Typical consequences of multi-medication and medical overuse may include an increased potential for drug interactions, an increased risk of adverse drug reactions and medication errors, and in particular in older adults, geriatric syndromes may occur or worsen. Adverse drug reactions may occur as a result of the dose administered and as an effect of time of exposure. Older, multi-morbid, and multi-medicated patients are often affected by adverse drug reactions. For drugs primarily metabolized via the phase I enzymes CYP2D6, CYP2C9, or CYP2C19, pharmacogenetically rapid or slow metabolism may result in altered drug exposures. Clinically relevant pharmacokinetic drug interactions frequently occur with drugs primarily metabolized via the phase I enzyme CYP3A4.

Review: Influence of the CYP450 Genetic Variation on the Treatment of Psychotic Disorders

Second-generation antipsychotic metabolism is mainly carried out by the CYP450 superfamily, which is highly polymorphic. Therefore, knowing the influence of the different known CYP450 polymorphisms on antipsychotic plasmatic levels and, consequently, the biological effect could contribute to a deeper knowledge of interindividual antipsychotic treatment variability, prompting possible solutions. Considering this, this state of the art review aimed to summarize the current knowledge about the influence of the diverse characterized phenotypes on the metabolism of the most used second-generation antipsychotics. Forty studies describing different single nucleotide polymorphisms (SNPs) associated with the genes CYP1A2, CYP2D6, CYP3A4, CYP3A5, and ABCB1 and their influence on pharmacokinetics of olanzapine, clozapine, aripiprazole, risperidone, and quetiapine. Most of the authors concluded that although significant differences in the pharmacokinetic parameters between the different phenotypes could be observed, more thorough studies describing pharmacokinetic interactions and environmental conditions, among other variables, are needed to fully comprehend these pharmacogenetic interactions.

Oral Yohimbine as a New Probe Drug to Predict CYP2D6 Activity: Results of a Fixed-Sequence Phase I Trial

Objective

Yohimbine pharmacokinetics were determined after oral administration of a single oral dose of yohimbine 5 mg and a microdose of yohimbine 50 µg in relation to different cytochrome P450 (CYP) 2D6 genotypes. The CYP2D6 inhibitor paroxetine was used to investigate the influence on yohimbine pharmacokinetics. Microdosed midazolam was applied to evaluate a possible impact of yohimbine on CYP3A activity and the possibility of combining microdosed yohimbine and midazolam to simultaneously determine CYP2D6 and CYP3A activity.

Methods

In a fixed-sequence clinical trial, 16 healthy volunteers with a known CYP2D6 genotype [extensive (10), intermediate (2) and poor (4) metaboliser] received an oral dose of yohimbine 50 µg, yohimbine 5 mg at baseline and during paroxetine as a CYP2D6 inhibitor. Midazolam (30 µg) was co-administered to determine CYP3A activity at each occasion. Plasma concentrations of yohimbine, its main metabolite 11-OH-yohimbine, midazolam and paroxetine were quantified using validated liquid chromatography-tandem mass spectrometry assays.

Results

Pharmacokinetics of yohimbine were highly variable and a CYP2D6 genotype dependent clearance was observed. After yohimbine 5 mg, the clearance ranged from 25.3 to 15,864 mL/min and after yohimbine 50 µg, the clearance ranged from 39.6 to 38,822 mL/min. A more than fivefold reduction in clearance was caused by paroxetine in CYP2D6 extensive metabolisers, while the clearance in poor metabolisers was not affected. Yohimbine did not alter CYP3A activity as measured by microdosed midazolam.

Conclusions

The pharmacokinetics of yohimbine were highly correlated with CYP2D6, which was further supported by the clearance inhibition caused by the CYP2D6 inhibitor paroxetine. With these data, yohimbine is proposed to be a suitable probe drug to predict CYP2D6 activity. In addition, the microdose can be used in combination with microdosed midazolam to simultaneously evaluate CYP2D6 and CYP3A activity without any interaction between the probe drugs and because the microdoses exert no pharmacological effects.

Clinical Trial Registration

EudraCT2017-001801-34.

Electronic supplementary material

The online version of this article (10.1007/s40262-020-00862-6) contains supplementary material, which is available to authorized users.

Pharmacokinetics and Pharmacodynamics of Approved and Investigational P2Y12 Receptor Antagonists

Coronary artery disease remains the major cause of mortality worldwide. Antiplatelet drugs such as acetylsalicylic acid and P2Y12 receptor antagonists are cornerstone treatments for the prevention of thrombotic events in patients with coronary artery disease. Clopidogrel has long been the gold standard but has major pharmacological limitations such as a slow onset and long duration of effect, as well as weak platelet inhibition with high inter-individual pharmacokinetic and pharmacodynamic variability. There has been a strong need to develop potent P2Y12 receptor antagonists with more favorable pharmacological properties. Prasugrel and ticagrelor are more potent and have a faster onset of action; however, they have shown an increased bleeding risk compared with clopidogrel. Cangrelor is highly potent and has a very rapid onset and offset of effect; however, its indication is limited to P2Y12 antagonist-naïve patients undergoing percutaneous coronary intervention. Two novel P2Y12 receptor antagonists are currently in clinical development, namely vicagrel and selatogrel. Vicagrel is an analog of clopidogrel with enhanced and more efficient formation of its active metabolite. Selatogrel is characterized by a rapid onset of action following subcutaneous administration and developed for early treatment of a suspected acute myocardial infarction. This review article describes the clinical pharmacology profile of marketed P2Y12 receptor antagonists and those under development focusing on pharmacokinetic, pharmacodynamic, and drug-drug interaction liability.

Oleuropein-Induced Acceleration of Cytochrome P450-Catalyzed Drug Metabolism: Central Role for Nuclear Receptor Peroxisome Proliferator-Activated Receptor α

Oleuropein (OLE), the main constituent of Olea europaea, displays pleiotropic beneficial effects in health and disease, which are mainly attributed to its anti-inflammatory and cardioprotective properties. Several food supplements and herbal medicines contain OLE and are available without a prescription. This study investigated the effects of OLE on the main cytochrome P450s (P450s) catalyzing the metabolism of many prescribed drugs. Emphasis was given to the role of peroxisome proliferator-activated receptor α (PPARα), a nuclear transcription factor regulating numerous genes including P450s. 129/Sv wild-type and Ppara-null mice were treated with OLE for 6 weeks. OLE induced Cyp1a1, Cyp1a2, Cyp1b1, Cyp3a14, Cyp3a25, Cyp2c29, Cyp2c44, Cyp2d22, and Cyp2e1 mRNAs in liver of wild-type mice, whereas no similar effects were observed in Ppara-null mice, indicating that the OLE-induced effect on these P450s is mediated by PPARα. Activation of the pathways related to phosphoinositide 3-kinase/protein kinase B (AKT)/forkhead box protein O1, c-Jun N-terminal kinase, AKT/p70, and extracellular signal-regulated kinase participates in P450 induction by OLE. These data indicate that consumption of herbal medicines and food supplements containing OLE could accelerate the metabolism of drug substrates of the above-mentioned P450s, thus reducing their efficacy and the outcome of pharmacotherapy. Therefore, OLE-induced activation of PPARα could modify the effects of drugs due to their increased metabolism and clearance, which should be taken into account when consuming OLE-containing products with certain drugs, in particular those of narrow therapeutic window. SIGNIFICANCE STATEMENT: This study indicated that oleuropein, which belongs to the main constituents of the leaves and olive drupes of Olea europaea, induces the synthesis of the major cytochrome P450s (P450s) metabolizing the majority of prescribed drugs via activation of peroxisome proliferator-activated receptor α. This effect could modify the pharmacokinetic profile of co-administered drug substrates of the P450s, thus altering their therapeutic efficacy and toxicity.

Variability of Pharmacogenomics Information in Drug Labels Approved by Different Agencies and Its Ethical Implications

AIMS

The aim of this study was to determine if there are discrepancies among various agency-approved labels for the same active ingredient and where the labels approved by the Turkish Medicines and Medical Devices Agency (TMMDA) stand regarding the inclusion of PGx and discuss these ethical implications.

BACKGROUND

The efficacy and safety of drugs can be improved by rational prescription and personalization of medicine for each patient. Pharmacogenomics information (PGx) in drug labels (DL) is one of the important tools for the personalization of medications because genetic differences may affect both drug efficacy and safety. Providing adequate PGx to patients has ethical implications.

OBJECTIVE

To evaluate PGx in the DLs approved by TMMDA and other national agencies provided by the Pharmacogenomics Knowledgebase.

METHODS

DL annotations from the Pharmacogenomics Knowledgebase and DLs approved by the TMMDA were analyzed according to information and action levels, which are "testing required", "testing recommended", "actionable", and "informative".

RESULTS

There are 381 drugs listed in PharmGKB drug label annotations with pharmacogenomics information and 278 of these have biomarkers. A total of 242 (63.5%) drugs are approved and available in Turkey. Of these, 207 (85.5%) contain the same information as in or similar to that in the labels approved by the other agencies. The presence and level of information varied among the DLs approved by different agencies. The inconsistencies may have an important effect on the efficacy and the safety of drugs.

CONCLUSION

These findings suggest a need for the standardization of PGx information globally because it may not only affect the efficacy and safety of medications but also essential ethical rules regarding patient rights by violating not sufficiently sharing all available information.

Synthesis and Bioinformatic Characterization of New Schiff Bases with Possible Applicability in Brain Disorders

(1) Background: The research aims to find new treatments for neurodegenerative diseases, in particular, Alzheimer’s disease. (2) Methods: This article presents a bioinformatics and pathology study of new Schiff bases, (EZ)-N′-benzylidene-(2RS)-2-(6-chloro-9H-carbazol-2-yl)propanehydrazide derivatives, and aims to evaluate the drug-like, pharmacokinetic, pharmacodynamic and pharmacogenomic properties, as well as to predict the binding to therapeutic targets by applying bioinformatics, cheminformatics and computational pharmacological methods. (3) Results: We obtained these Schiff bases by condensing (2RS)-2-(6-chloro-9H-carbazol-2-yl)propanehydrazide with aromatic aldehydes, using the advantages of microwave irradiation. The newly synthesized compounds were characterized spectrally, using FT-IR and NMR spectroscopy, which confirmed their structure. Using bioinformatics tools, we noticed that all new compounds are drug-likeness features and may be proposed as potentially neuropsychiatric drugs (4) Conclusions: Using bioinformatics tools, we determined that the new compound 1e had a high potential to be used as a good candidate in neurodegenerative disorders treatment.

Methylphenidate and atomoxetine treatment negatively affect physical growth indexes of school-age children and adolescents with attention-deficit/hyperactivity disorder

AIM

To determine the effects of drug therapy on the physical growth of school-age children and adolescents with attention-deficit/hyperactivity disorder (ADHD).

METHOD

The medical records of 86 participants (average age: 8.9 ± 2.2 years) with ADHD prescribed methylphenidate (MPH) or atomoxetine (ATX) for ≥24 weeks from the Children's Hospital of Chongqing Medical University were analysed.

RESULTS

The Z-scores of height, weight and body mass index (BMI) of children with ADHD decreased significantly over the first six months of MPH treatment (P < 0.001). The slopes of the fitting lines after the first six months of MPH (-0.18, -0.58 and -0.69, respectively) returned over the entire treatment (the slopes changed to -0.027, -0.26 and -0.20, respectively). For ATX, the Z-scores of height of children decreased significantly over the first six months (P < 0.001), but the Z-scores of weight and BMI did not (P > 0.05). The slopes of the fitting lines after the first six months of ATX (-0.058, -0.032 and 0.0094, respectively) changed over the entire treatment (slopes were 0.16, 0.52 and 0.26, respectively). Children taking MPH were more likely to report decreased appetite (P < 0.05). The weight and BMI of the children receiving MPH were significantly correlated with decreased appetite (P < 0.01).

CONCLUSION

The physical growth indexes (PGIs) of school-age children and adolescents with ADHD were negatively affected while taking MPH, and these effects were gradually mitigated with continued treatment. ATX hardly had negative effects on weight and BMI. Neither MPH nor ATX had a significant negative effect on the height of children in long-term ADHD treatment. It is necessary for clinicians to consider children's diet during treatment.

Prevalence of five pharmacologically most important CYP2C9 and CYP2C19 allelic variants in the population from the Republic of Srpska in Bosnia and Herzegovina

The enzymes of the cytochrome P450 superfamily play a critical role in phase I drug metabolism. Among them, CYP2C9 and CYP2C19 are clinically important, as they can mediate severe toxicity, therapy failure, and increased susceptibility to cancer and other diseases caused by chemicals. The aim of this study was to determine the prevalence of pharmacologically most important allelic variants of the CYP2C9 and CYP2C19 genes in the general population of the Republic of Srpska (Bosnia and Herzegovina) and to compare them with other populations. For this purpose we determined the genotype profile and allele frequency of 216 randomly selected healthy volunteers using real-time polymerase chain reaction (RT-PCR). The prevalence of the CYP2C9 *2 and *3 alleles was 13.6 and 7.4 %, respectively. Based on these frequencies, of the 216 participants four (1.86 %) were predicted to be poor metabolisers, 78 (36.11 %) intermediate, and the remaining 134 (62.03 %) normal metabolisers. Based on the prevalence of CYP2C19 *2 and *17 variants – 16.2 and 20.4 %, respectively – nine (4.17 %) were predicted to be poor, 57 (26.39 %) rapid, and nine (4.17 %) ultra-rapid metabolisers. We found no significant differences in allele frequencies in our population and populations from other European countries. These findings suggest that genetically determined phenotypes of CYP2C9 and CYP2C19 should be taken into consideration to minimise individual risk and improve benefits of drug therapy in the Republic of Srpska.

The Central Role of Cytochrome P450 in Xenobiotic Metabolism-A Brief Review on a Fascinating Enzyme Family

Human Cytochrome P450 (CYP) enzymes constitute a superfamily of membrane-bound hemoproteins that are responsible for the metabolism of a wide variety of clinically, physiologically, and toxicologically important compounds. These heme-thiolate monooxygenases play a pivotal role in the detoxification of xenobiotics, participating in the metabolism of many structurally diverge compounds. This short-review is intended to provide a summary on the major roles of CYPs in Phase I xenobiotic metabolism. The manuscript is focused on eight main topics that include the most relevant aspects of past and current CYP research. Initially, (I) a general overview of the main aspects of absorption, distribution, metabolism, and excretion (ADME) of xenobiotics are presented. This is followed by (II) a background overview on major achievements in the past of the CYP research field. (III) Classification and nomenclature of CYPs is briefly reviewed, followed by (IV) a summary description on CYP's location and function in mammals. Subsequently, (V) the physiological relevance of CYP as the cornerstone of Phase I xenobiotic metabolism is highlighted, followed by (VI) reviewing both genetic determinants and (VI) nongenetic factors in CYP function and activity. The last topic of the review (VIII) is focused on the current challenges of the CYP research field.

Pharmacogenomics of NSAID-Induced Upper Gastrointestinal Toxicity

Non-steroidal anti-inflammatory drugs (NSAIDs) are a group of drugs which are widely used globally for the treatment of pain and inflammation, and in the case of aspirin, for secondary prevention of cardiovascular disease. Chronic non-steroidal anti-inflammatory drug use is associated with potentially serious upper gastrointestinal adverse drug reactions (ADRs) including peptic ulcer disease and gastrointestinal bleeding. A few clinical and genetic predisposing factors have been identified; however, genetic data are contradictory. Further research is needed to identify clinically relevant genetic and non-genetic markers predisposing to NSAID-induced peptic ulceration.

Functional assessment of the effects of CYP3A4 variants on acalabrutinib metabolism in vitro

AIM

We aimed (i) to study the effects of genetic polymorphism of cytochrome P450 3A4 (CYP3A4) and drug interactions on acalabrutinib (ACA) metabolism and (ii) to investigate the mechanisms underlying the effects of CYP3A4 variants on the differential kinetic profiles of ACA and ibrutinib.

METHOD

Recombinant human CYP3A4 and variants were expressed using a Bac-to-Bac baculovirus expression system. The cell microsome was prepared and subjected to kinetic study. The analyte concentrations were determined by UPLC-MS/MS. A molecular docking assay was employed to investigate the mechanisms leading to differences in kinetic profiles.

RESULTS

The kinetic parameters of ACA, catalyzed by CYP3A4 and 28 of its variants, were determined, including V_max, K_m, and K_si. CYP3A4.6-8, 12, 13, 17, 18, 20, and 30 lost their catalytic function. No significant differences were found for CYP3A4.4, 5, 10, 15, 31, and 34 compared with CYP3A4.1 with respect to intrinsic clearance (V_max/K_m, Clint). However, the Clint values of CYP3A4.9, 14, 16, 19, 23, 24, 28, 32 were obviously decreased, ranging from 0.02 to 0.05 μL/min/pmol. On the contrary, the catalytic activities of CYP3A4.2, 3, 11, 29, and 33 were increased dramatically. The Clint value of CYP3A4.11 was 5.95 times as high as that of CYP3A4.1. Subsequently, CYP3A4.1, 3, 11, 23, and 28 were chosen to study the kinetic changes in combination with ketoconazole. Interestingly, we found the inhibitory potency of ketoconazole varied in different variants. In addition, the kinetic parameters of ibrutinib and ACA were accordingly compared in different CYP3A4 variants. Significant differences in relative clearance were observed among variants, which would probably influence the distance between the redox site and the heme iron atom.

CONCLUSION

Genetic polymorphism of CYP3A4 extensively changes its ACA-metabolizing enzymatic activity. In combination with a CYP inhibitor, its inhibitory potency also varied among different variants. Even the same variants exhibited different capabilities catalyzing ACA. Its enzymatic capabilities are probably determined by the distance between the substrate and the heme iron atom, which could be impacted by mutation.

CYP2D6 Basic Genotyping of Patients with Chronic Pain Receiving Tramadol or Codeine. A Study in a Greek Cohort

OBJECTIVE

To assess CYP2D6 genotype prevalence in chronic pain patients treated with tramadol or codeine.

DESIGN

Prospective cohort study.

SETTING

General hospital, pain management unit.

SUBJECTS

Patients with chronic pain, treated with codeine or tramadol.

METHODS

Patients' pain was assessed at baseline (numeric rating scale [NRS]; 0-10). Prescription of codeine or tramadol was selected randomly. The assessment of patients' response to the drug in terms of pain relief and adverse effects was performed after 24 hours. Reduction of pain intensity of >50% or an NRS <4 was considered a positive response. Patients' blood samples were collected during the first visit. Genotyping for the common variants CYP2D6 *2, *3, *4, *5, *6, *9, *10, *14, and *17 was performed, and alleles not carrying any polymorphic allele were classified as CYP2D6*1 (wild-type [wt]).

RESULTS

Seventy-six consecutive patients were studied (20 males, 56 females), aged 21-85 years. Thirty-four received tramadol and 42 codeine. The main genotypes of CYP2D6 identified were the wt/wt (35.5%), the *4/wt (17.1%), and the *6/wt (10.5%). Adverse effects were common, especially in carriers of *9/*9, *5/*5, *5/*4, and *10/*10, as well as in variants including the 4 allele (*4/*1 [38.4%] and *4/*4 [42.8%]).

CONCLUSIONS

Genotyping can facilitate personalized pain management with opioids, as specific alleles are related to decreased efficacy and adverse effects.

Recent advances in computational metabolite structure predictions and altered metabolic pathways assessment to inform drug development processes

Many drug candidates fail during preclinical and clinical trials due to variable or unexpected metabolism which may lead to variability in drug efficacy or adverse drug reactions. The drug metabolism field aims to address this important issue from many angles which range from the study of drug-drug interactions, pharmacogenomics, computational metabolic modeling, and others. This manuscript aims to provide brief but comprehensive manuscript summaries highlighting the conclusions and scientific importance of seven exceptional manuscripts published in recent years within the field of drug metabolism. Two main topics within the field are reviewed: novel computational metabolic modeling approaches which provide complex outputs beyond site of metabolism predictions, and experimental approaches designed to discern the impacts of interindividual variability and species differences on drug metabolism. The computational approaches discussed provide novel outputs in metabolite structure and formation likelihood and/or extend beyond the saturated field of drug phase I metabolism, while the experimental metabolic pathways assessments aim to highlight the impacts of genetic polymorphisms and clinical animal model metabolic differences on human metabolism and subsequent health outcomes.

CYP2D6 in the Brain: Potential Impact on Adverse Drug Reactions in the Central Nervous System-Results From the ADRED Study

Cytochrome P450 (CYP) 2D6 is a polymorphic enzyme expressed in the central nervous system (CNS), important in drug metabolism and with a potentially constitutive role in CNS function such as vigilance. This study aimed to analyze variability in CYP2D6 activity linked to vigilance-related adverse drug reactions (ADRs) in the CNS. A dataset of N = 2939 ADR cases of the prospective multicenter observational trial in emergency departments (EDs) (ADRED; trial registration: DRKS-ID: DRKS00008979) was analyzed. Dizziness as the most frequent reported CNS ADR symptom (12.7% of patients, n = 372) related to vigilance was chosen as the outcome. The association of dizziness with CYP2D6 activity markers was analyzed. The number of CYP2D6 substrates taken, a CYP2D6 saturation score (no, moderate, and strong saturation), a CYP2D6 saturation/inhibition score (no, weak, moderate, and strong), and composed CYP2D6 activity using a genotyped subsample (n = 740) calculating additive effects of genotype and CYP2D6 saturation by drug exposure were used as CYP2D6 activity markers. Effects were compared to other frequent nonvigilance-related CNS ADR symptoms (syncope and headache). Secondary analyses were conducted to control for other ADR symptoms frequently associated with dizziness (syncope, nausea, and falls). The majority of all patients (64.5%, n = 1895) took at least one drug metabolized by CYP2D6. Around a third took a CNS drug (32.5%, n = 955). The chance to present with drug-related dizziness to the ED increased with each CYP2D6 substrate taken by OR 1.11 [1.01–1.23]. Presenting with drug-related dizziness was more likely with CYP2D6 saturation and saturation/inhibition (both OR 1.27 [1.00–1.60]). The composed CYP2D6 activity was positively associated with dizziness (p = 0.028), while poorer activity affected patients more often with dizziness as an ADR. In contrast, nonvigilance-related ADR symptoms such as syncope and nausea were not consistently significantly associated with CYP2D6 activity markers. This study shows an association between the number of CYP2D6 substrates, the predicted CYP2D6 activity, and the occurrence of dizziness as a CNS ADR symptom. As dizziness is a vigilance-related CNS symptom, patients with low CYP2D6 activity might be more vulnerable to drug-related dizziness. This study underlines the need for understanding individual drug metabolism activity and individual risks for ADRs.