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Guo HL, Wu DD, Fu D, Li Y, Wang J, Zhang YY, Wang WJ, Huang J, Fang WR, Xu J, Hu YH, Liu QQ, Chen F. Individualized atomoxetine response and tolerability in children with ADHD receiving different dosage regimens: the need for CYP2D6 genotyping and therapeutic drug monitoring to dance together. Transl Psychiatry 2024; 14:151. [PMID: 38504095 PMCID: PMC10951231 DOI: 10.1038/s41398-024-02859-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 03/04/2024] [Accepted: 03/06/2024] [Indexed: 03/21/2024] Open
Abstract
Integrating CYP2D6 genotyping and therapeutic drug monitoring (TDM) is crucial for guiding individualized atomoxetine therapy in children with attention-deficit/hyperactivity disorder (ADHD). The aim of this retrospective study was (1) to investigate the link between the efficacy and tolerability of atomoxetine in children with ADHD and plasma atomoxetine concentrations based on their CYP2D6 genotypes; (2) to offer TDM reference range recommendations for atomoxetine based on the CYP2D6 genotypes of children receiving different dosage regimens. This retrospective study covered children and adolescents with ADHD between the ages of 6 and <18, who visited the psychological and behavioral clinic of Children's Hospital of Nanjing Medical University from June 1, 2021, to January 31, 2023. The demographic information and laboratory examination data, including CYP2D6 genotype tests and routine TDM of atomoxetine were obtained from the hospital information system. We used univariate analysis, Mann-Whitney U nonparametric test, Kruskal-Wallis test, and the receiver operating characteristic (ROC) curve to investigate outcomes of interest. 515 plasma atomoxetine concentrations of 385 children (325 boys and 60 girls) with ADHD between 6 and 16 years of age were included for statistical analysis in this study. Based on genotyping results, >60% of enrolled children belonged to the CYP2D6 extensive metabolizer (EM), while <40% fell into the intermediate metabolizer (IM). CYP2D6 IMs exhibited higher dose-corrected plasma atomoxetine concentrations by 1.4-2.2 folds than those CYP2D6 EMs. Moreover, CYP2D6 IMs exhibited a higher response rate compare to EMs (93.55% vs 85.71%, P = 0.0132), with higher peak plasma atomoxetine concentrations by 1.67 times than those of EMs. Further ROC analysis revealed that individuals under once daily in the morning (q.m.) dosing regimen exhibited a more effective response to atomoxetine when their levels were ≥ 268 ng/mL (AUC = 0.710, P < 0.001). In addition, CYP2D6 IMs receiving q.m. dosing of atomoxetine were more likely to experience adverse reactions in the central nervous system and gastrointestinal system when plasma atomoxetine concentrations reach 465 and 509 ng/mL, respectively. The findings in this study provided promising treatment strategy for Chinese children with ADHD based on their CYP2D6 genotypes and plasma atomoxetine concentration monitoring. A peak plasma atomoxetine concentration higher than 268 ng/mL might be requisite for q.m. dosing. Assuredly, to validate and reinforce these initial findings, it is necessary to collect further data in controlled studies with a larger sample size.
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Affiliation(s)
- Hong-Li Guo
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Dan-Dan Wu
- Department of Children Health Care, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Di Fu
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
- Visiting graduate student from China Pharmaceutical University, Nanjing, China
| | - Yue Li
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Jie Wang
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Yuan-Yuan Zhang
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Wei-Jun Wang
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
- Visiting graduate student from China Pharmaceutical University, Nanjing, China
| | - Jian Huang
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Wei-Rong Fang
- School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Jing Xu
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Ya-Hui Hu
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China.
| | - Qian-Qi Liu
- Department of Children Health Care, Children's Hospital of Nanjing Medical University, Nanjing, China.
| | - Feng Chen
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China.
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Stern S, Hyland PL, Pacanowski M, Schuck RN. Leveraging in Vitro Models for Clinically Relevant Rare CYP2D6 Variants in Pharmacogenomics. Drug Metab Dispos 2024; 52:159-170. [PMID: 38167410 PMCID: PMC10877705 DOI: 10.1124/dmd.123.001512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/09/2023] [Accepted: 12/19/2023] [Indexed: 01/05/2024] Open
Abstract
Cytochrome P450 2D6 (CYP2D6) is responsible for the metabolism of up to 20% of small-molecule drugs and therefore, may impact the safety and efficacy of medicines in broad therapeutic areas. CYP2D6 is highly polymorphic, and the frequency of variants can differ across racial and ethnic populations, significantly affecting enzymatic function and drug metabolism. However, rare variants of CYP2D6 present a unique challenge for academia, industry, and regulatory agencies alike due to the lack of feasibility of characterizing their clinical relevance in clinical trials, particularly in variants that exhibit population-specific frequencies in racial and ethnic groups that are poorly represented in clinical trials. Despite significant advancement in pharmacogenomics, the substrate specificity and related clinical relevance of these CYP2D6 rare variants remain largely unclear, and further efforts are warranted to characterize the burden of these variants on adverse drug reactions and drug efficacy. Thus, cell-based in vitro systems can be used to inform substrate-specific effects and the overall relevance of a rare variant. Liver microsomes, cell-based expression systems, ex vivo primary samples, and purified variant protein have all been used with various substrates to potentially predict the clinical impact of new substrates. In this review, we identify rare variants of CYP2D6 that demonstrate differences across races in prevalence and thus are often unassessed in clinical trials. Accordingly, we examine current pharmacogenomic in vitro models used to analyze the functional impact of these rare variants in a substrate-specific manner. SIGNIFICANCE STATEMENT: Variants of CYP2D6 play a clinically relevant role in drug metabolism, leading to potential safety and efficacy concerns. Although the influence of prevalent variants is often well characterized, rare variants are traditionally not included in clinical trials. This review captures the clinical relevance of rare variants in CYP2D6 by highlighting in vitro models that analyze their impact on the metabolism of CYP2D6 substrates.
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Affiliation(s)
- Sydney Stern
- Center for Drug Evaluation and Research, Office of Translational Science, Office of Clinical Pharmacology, US Food and Drug Administration, Silver Spring, Maryland
| | - Paula L Hyland
- Center for Drug Evaluation and Research, Office of Translational Science, Office of Clinical Pharmacology, US Food and Drug Administration, Silver Spring, Maryland
| | - Michael Pacanowski
- Center for Drug Evaluation and Research, Office of Translational Science, Office of Clinical Pharmacology, US Food and Drug Administration, Silver Spring, Maryland
| | - Robert N Schuck
- Center for Drug Evaluation and Research, Office of Translational Science, Office of Clinical Pharmacology, US Food and Drug Administration, Silver Spring, Maryland
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Fu D, Guo HL, Hu YH, Fang WR, Liu QQ, Xu J, Wu DD, Chen F. Personalizing atomoxetine dosing in children with ADHD: what can we learn from current supporting evidence. Eur J Clin Pharmacol 2023; 79:349-70. [PMID: 36645468 DOI: 10.1007/s00228-022-03449-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 12/20/2022] [Indexed: 01/17/2023]
Abstract
PURPOSE There is marked heterogeneity in treatment response of atomoxetine in patients with attention deficit/hyperactivity disorder (ADHD), especially for the pediatric population. This review aims to evaluate current evidence to characterize the dose-exposure relationship, establish clinically relevant metrics for systemic exposure to atomoxetine, define a therapeutic exposure range, and to provide a dose-adaptation strategy before implementing personalized dosing for atomoxetine in children with ADHD. METHODS A comprehensive search was performed across electronic databases (PubMed and Embase) covering the period of January 1, 1985 to July 10, 2022, to summarize recent advances in the pharmacokinetics, pharmacogenomics/pharmacogenetics (PGx), therapeutic drug monitoring (TDM), physiologically based pharmacokinetics (PBPK), and population pharmacokinetics (PPK) of atomoxetine in children with ADHD. RESULTS Some factors affecting the pharmacokinetics of atomoxetine were summarized, including food, CYP2D6 and CYP2C19 phenotypes, and drug‒drug interactions (DDIs). The association between treatment response and genetic polymorphisms of genes encoding pharmacological targets, such as norepinephrine transporter (NET/SLC6A2) and dopamine β hydroxylase (DBH), was also discussed. Based on well-developed and validated assays for monitoring plasma concentrations of atomoxetine, the therapeutic reference range in pediatric patients with ADHD proposed by several studies was summarized. However, supporting evidence on the relationship between systemic atomoxetine exposure levels and clinical response was far from sufficient. CONCLUSION Personalizing atomoxetine dosage may be even more complex than anticipated thus far, but elucidating the best way to tailor the non-stimulant to a patient's individual need will be achieved by combining two strategies: detailed research in linking the pharmacokinetics and pharmacodynamics in pediatric patients, and better understanding in nature and causes of ADHD, as well as environmental stressors.
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Dong AN, Ahemad N, Pan Y, Palanisamy UD, Yiap BC, Ong CE. Role of P34S, G169R, R296C, and S486T Substitutions in Ligand Access and Catalysis for Cytochrome P450 2D6 Allelic Variants CYP2D6*14A and CYP2D6*14B. Drug Metab Bioanal Lett 2022; 15:51-63. [PMID: 35049443 DOI: 10.2174/1872312815666220113125232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 11/16/2021] [Accepted: 12/17/2021] [Indexed: 06/14/2023]
Abstract
BACKGROUND Genetic polymorphism of cytochrome P450 (CYP) contributes to variability in drug metabolism, clearance, and response. This study aimed to investigate the functional and molecular basis for altered ligand binding and catalysis in CYP2D6*14A and CYP2D6*14B, two unique alleles common in the Asian population. METHODS CYP proteins expressed in Escherichia coli were studied using the substrate 3-cyano-7- ethoxycoumarin (CEC) and inhibitor probes (quinidine, fluoxetine, paroxetine, terbinafine) in the enzyme assay. Computer modelling was additionally used to create three-dimensional structures of the CYP2D6*14 variants. RESULTS Kinetics data indicated significantly reduced intrinsic clearance in CYP2D6*14 variants, suggesting that P34S, G169R, R296C, and S486T substitutions worked cooperatively to alter the conformation of the active site that negatively impacted the deethylase activity of CYP2D6. For the inhibition studies, IC50 values decreased in quinidine, paroxetine, and terbinafine but increased in fluoxetine, suggesting a varied ligand-specific susceptibility to inhibition. Molecular docking further demonstrated the role of P34S and R296C in altering access channel dimensions, thereby affecting ligand access and binding and subsequently resulting in varied inhibition potencies. CONCLUSION In summary, the differential selectivity of CYP2D6*14 variants for the ligands (substrate and inhibitor) was governed by the alteration of the active site and access channel architecture induced by the natural mutations found in the alleles.
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Affiliation(s)
| | - Nafees Ahemad
- School of Pharmacy, Monash University Malaysia, Selangor, Malaysia
| | - Yan Pan
- Department of Biomedical Science, University of Nottingham, Malaysia Campus, Semenyih, Selangor, Malaysia
| | - Uma Devi Palanisamy
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Jalan Lagoon Selatan, Selangor, Malaysia
| | - Beow Chin Yiap
- School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Chin Eng Ong
- School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
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Shad MU. Genetic Testing for Antipsychotic Pharmacotherapy: Bench to Bedside. Behav Sci (Basel) 2021; 11:97. [PMID: 34209185 DOI: 10.3390/bs11070097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/12/2021] [Accepted: 06/23/2021] [Indexed: 11/24/2022] Open
Abstract
There is growing research interest in learning the genetic basis of response and adverse effects with psychotropic medications, including antipsychotic drugs. However, the clinical utility of information from genetic studies is compromised by their controversial results, primarily due to relatively small effect and sample sizes. Clinical, demographic, and environmental differences in patient cohorts further explain the lack of consistent results from these genetic studies. Furthermore, the availability of psychopharmacological expertise in interpreting clinically meaningful results from genetic assays has been a challenge, one that often results in suboptimal use of genetic testing in clinical practice. These limitations explain the difficulties in the translation of psychopharmacological research in pharmacogenetics and pharmacogenomics from bench to bedside to manage increasingly treatment-refractory psychiatric disorders, especially schizophrenia. Although these shortcomings question the utility of genetic testing in the general population, the commercially available genetic assays are being increasingly utilized to optimize the effectiveness of psychotropic medications in the treatment-refractory patient population, including schizophrenia. In this context, patients with treatment-refractory schizophrenia are among of the most vulnerable patients to be exposed to the debilitating adverse effects from often irrational and high-dose antipsychotic polypharmacy without clinically meaningful benefits. The primary objective of this comprehensive review is to analyze and interpret replicated findings from the genetic studies to identify specific genetic biomarkers that could be utilized to enhance antipsychotic efficacy and tolerability in the treatment-refractory schizophrenia population.
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Shin W, Bang M, Kim A, Cho DY, Lee SH. Influence of cytochrome P450 2D6 polymorphism on hippocampal white matter and treatment response in schizophrenia. NPJ Schizophr 2021; 7:5. [PMID: 33514751 DOI: 10.1038/s41537-020-00134-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Accepted: 11/12/2020] [Indexed: 12/16/2022]
Abstract
Cytochrome P450 2D6 (CYP2D6) is expressed at high levels in the brain and plays a considerable role in the biotransformation and neurotransmission of dopamine. This raises the question of whether CYP2D6 variations and its impact on the brain can confer susceptibility to schizophrenia. We investigated the possible links among the CYP2D6 genotype, white matter (WM) integrity of the hippocampus, and the treatment response to antipsychotic drugs in Korean patients with schizophrenia (n = 106). Brain magnetic resonance imaging and genotyping for CYP2D6 were conducted at baseline. The severity of clinical symptoms and the treatment response were assessed using the Positive and Negative Syndrome Scale (PANSS). After genotyping, 43 participants were classified as intermediate metabolizers (IM), and the remainder (n = 63) were classified as extensive metabolizers (EM). IM participants showed significantly higher fractional anisotropy (FA) values in the right hippocampus compared to EM participants. Radial diffusivity (RD) values were significantly lower in the overlapping region of the right hippocampus in the IM group than in the EM group. After 4 weeks of antipsychotic treatment, the EM group showed more improvements in positive symptoms than the IM group. FAs and RDs in the CYP2D6-associated hippocampal WM region were significantly correlated with a reduction in the positive symptom subscale of the PANSS. Greater improvements in positive symptoms were negatively associated with FAs, and positively associated with RDs in the right hippocampal region. The findings suggest that CYP26D-associated hippocampal WM alterations could be a possible endophenotype for schizophrenia that accounts for individual differences in clinical features and treatment responses.
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Williams I, Gatchie L, Bharate SB, Chaudhuri B. Biotransformation, Using Recombinant CYP450-Expressing Baker's Yeast Cells, Identifies a Novel CYP2D6.10 A122V Variant Which Is a Superior Metabolizer of Codeine to Morphine Than the Wild-Type Enzyme. ACS Omega 2018; 3:8903-8912. [PMID: 31459022 PMCID: PMC6644518 DOI: 10.1021/acsomega.8b00809] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 07/30/2018] [Indexed: 05/29/2023]
Abstract
CYP2D6, a cytochrome P450 (CYP) enzyme, metabolizes codeine to morphine. Within the human body, 0-15% of codeine undergoes O-demethylation by CYP2D6 to form morphine, a far stronger analgesic than codeine. Genetic polymorphisms in wild-type CYP2D6 (CYP2D6-wt) are known to cause poor-to-extensive metabolism of codeine and other CYP2D6 substrates. We have established a platform technology that allows stable expression of human CYP genes from chromosomal loci of baker's yeast cells. Four CYP2D6 alleles, (i) chemically synthesized CYP2D6.1, (ii) chemically synthesized CYP2D6-wt, (iii) chemically synthesized CYP2D6.10, and (iv) a novel CYP2D6.10 variant CYP2D6-C (i.e., CYP2D6.10A122V) isolated from a liver cDNA library, were cloned for chromosomal integration in yeast cells. When expressed in yeast, CYP2D6.10 enzyme shows weak activity compared with CYP2D6-wt and CYP2D6.1 which have moderate activity, as reported earlier. Surprisingly, however, the CYP2D6-C enzyme is far more active than CYP2D6.10. More surprisingly, although CYP2D6.10 is a known low metabolizer of codeine, yeast cells expressing CYP2D6-C transform >70% of codeine to morphine, which is more than twice that of cells expressing the extensive metabolizers, CYP2D6.1, and CYP2D6-wt. The latter two enzymes predominantly catalyze formation of codeine's N-demethylation product, norcodeine, with >55% yield. Molecular modeling studies explain the specificity of CYP2D6-C for O-demethylation, validating observed experimental results. The yeast-based CYP2D6 expression systems, described here, could find generic use in CYP2D6-mediated drug metabolism and also in high-yield chemical reactions that allow the formation of regio-specific dealkylation products.
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Affiliation(s)
- Ibidapo
S. Williams
- CYP
Design Ltd, The Innovation Centre, 49 Oxford Street, Leicester LE1 5XY, U.K.
| | - Linda Gatchie
- CYP
Design Ltd, The Innovation Centre, 49 Oxford Street, Leicester LE1 5XY, U.K.
| | - Sandip B. Bharate
- Medicinal
Chemistry Division, CSIR-Indian Institute
of Integrative Medicine, Canal Road, Jammu 180001, India
| | - Bhabatosh Chaudhuri
- CYP
Design Ltd, The Innovation Centre, 49 Oxford Street, Leicester LE1 5XY, U.K.
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Kim SH, Byeon JY, Kim YH, Lee CM, Lee YJ, Jang CG, Lee SY. Physiologically based pharmacokinetic modelling of atomoxetine with regard to CYP2D6 genotypes. Sci Rep 2018; 8:12405. [PMID: 30120390 PMCID: PMC6098032 DOI: 10.1038/s41598-018-30841-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 08/07/2018] [Indexed: 01/20/2023] Open
Abstract
Atomoxetine is a norepinephrine reuptake inhibitor indicated in the treatment of attention-deficit/hyperactivity disorder. It is primarily metabolized by CYP2D6 to its equipotent metabolite, 4-hydroxyatomoxetine, which promptly undergoes further glucuronidation to an inactive 4-HAT-O-glucuronide. Clinical trials have shown that decreased CYP2D6 activity leads to substantially elevated atomoxetine exposure and increase in adverse reactions. The aim of this study was to to develop a pharmacologically based pharmacokinetic (PBPK) model of atomoxetine in different CYP2D6 genotypes. A single 20 mg dose of atomoxetine was given to 19 healthy Korean individuals with CYP2D6*wt/*wt (*wt = *1 or *2) or CYP2D6*10/*10 genotype. Based on the results of this pharmacokinetic study, a PBPK model for CYP2D6*wt/*wt individuals was developed. This model was scaled to those with CYP2D6*10/*10 genotype, as well as CYP2D6 poor metabolisers. We validated this model by comparing the predicted pharmacokinetic parameters with diverse results from the literature. The presented PBPK model describes the pharmacokinetics after single and repeated oral atomoxetine doses with regard to CYP2D6 genotype and phenotype. This model could be utilized for identification of appropriate dosages of atomoxetine in patients with reduced CYP2D6 activity to minimize the adverse events, and to enable personalised medicine.
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Affiliation(s)
- Se-Hyung Kim
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Ji-Young Byeon
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Young-Hoon Kim
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Choong-Min Lee
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Yun Jeong Lee
- College of Pharmacy, Dankook University, Cheonan, 31116, Republic of Korea
| | - Choon-Gon Jang
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Seok-Yong Lee
- School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
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Shen Y, Luo Z, Yu Q, Wang Y, Xiang J, Miao J. Pharmacokinetics of dimemorfan phosphate tablets in healthy Chinese volunteers. Eur J Clin Pharmacol 2017; 73:709-715. [PMID: 28243685 DOI: 10.1007/s00228-017-2211-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 01/30/2017] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Investigate the pharmacokinetic properties of the antitussive dimemorfan phosphate tablets in healthy male and female Chinese volunteers after single and multiple-dose administration; and to evaluate the food-effect on pharmacokinetics of dimemorfan. METHODS 12 subjects received a single dose of 10 mg and 40 mg dimemorfan phosphate tablets, respectively in study stage 1. Another 12 subjects received a single dose of 20 mg dimemorfan phosphate tablets under fed conditions, a single dose of 20 mg dimemorfan phosphate tablets under fasting conditions and multiple-dosing of 20 mg dimemorfan phosphate tablets 3 times per day, respectively in study stage 2. The washout between each treatment was 1 week. Plasma dimemorfan was quantified by a high pressure liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method. RESULTS After single-dosing of 10 mg, 20 mg and 40 mg dimemorfan phosphate tablets, Cmax, AUC0-t and AUC0-∞ were dose proportional, which achievd 6.19 ± 7.61 ng·mL-1, 101 ± 171 and 117 ± 210 ng·mL-1·h, respectively after single-dosing of 40 mg dimemorfan phosphate tablets. Tmax ranged from 2.75 to 3.96 h and t1/2 ranged from 10.6 to 11.4 h. After multiple-dosing of 20 mg dimemorfan phosphate tablets, the Accumulation Index (AI) was 2.65 ± 1.11. The pharmacokinetic parameters after single-dosing of 20 mg dimemorfan phosphate tablets under fed conditions were similar with those under fasting conditions. Sex did not affect the pharmacokinetics of dimemorfan phosphate tablets. CONCLUSIONS Single-dosing of dimemorfan phosphate tablets exhibited linear kinetic characteristics. Multiple-dosing of 20 mg dimemorfan phosphate tablets 3 times per day caused obvious accumulation. No food effect or sex effect on the pharmacokinetics of dimemorfan phosphate tablets was observed. Chictr.org identifier: ChiCTR-ONC-14004851.
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Affiliation(s)
- Yali Shen
- Department of Abdominal Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Zhu Luo
- GCP Center / Institute of Drug Clinical Trials, West China Hospital, Sichuan University, Chengdu, 610041, People's Republic of China.
| | - Qin Yu
- GCP Center / Institute of Drug Clinical Trials, West China Hospital, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Ying Wang
- GCP Center / Institute of Drug Clinical Trials, West China Hospital, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Jin Xiang
- GCP Center / Institute of Drug Clinical Trials, West China Hospital, Sichuan University, Chengdu, 610041, People's Republic of China
| | - Jia Miao
- GCP Center / Institute of Drug Clinical Trials, West China Hospital, Sichuan University, Chengdu, 610041, People's Republic of China
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Dorado P, González I, Naranjo MEG, de Andrés F, Peñas-Lledó EM, Calzadilla LR, LLerena A. Lessons from Cuba for Global Precision Medicine: CYP2D6 Genotype Is Not a Robust Predictor of CYP2D6 Ultrarapid Metabolism. ACTA ACUST UNITED AC 2017; 21:17-26. [DOI: 10.1089/omi.2016.0166] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Pedro Dorado
- CICAB, Clinical Research Centre, Extremadura University Hospital and Medical School, Badajoz, Spain
| | - Idilio González
- Centro de Salud Mental, Área de Salud Zafra-Llerena, Servicio Extremeño de Salud, Llerena, Spain
| | - María Eugenia G. Naranjo
- CICAB, Clinical Research Centre, Extremadura University Hospital and Medical School, Badajoz, Spain
| | - Fernando de Andrés
- CICAB, Clinical Research Centre, Extremadura University Hospital and Medical School, Badajoz, Spain
- Department of Analytical Chemistry and Food Technology, Faculty of Pharmacy, University of Castilla-La Mancha, Albacete, Spain
| | - Eva María Peñas-Lledó
- CICAB, Clinical Research Centre, Extremadura University Hospital and Medical School, Badajoz, Spain
| | | | - Adrián LLerena
- CICAB, Clinical Research Centre, Extremadura University Hospital and Medical School, Badajoz, Spain
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Pei Q, Huang L, Huang J, Gu JK, Kuang Y, Zuo XC, Ding JJ, Tan HY, Guo CX, Liu SK, Yang GP. Influences of CYP2D6 *10 polymorphisms on the pharmacokinetics of iloperidone and its metabolites in Chinese patients with schizophrenia: a population pharmacokinetic analysis. Acta Pharmacol Sin 2016; 37:1499-1508. [PMID: 27665849 DOI: 10.1038/aps.2016.96] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 07/24/2016] [Indexed: 01/15/2023] Open
Abstract
AIM Iloperidone is an atypical antipsychotic drug that is mainly metabolized by CYP2D6, CYP3A4, and cytosolic enzymes. Previous studies show that extensive and poor metabolizers of CYP2D6 exhibit different plasma concentrations of iloperidone and its metabolites. The aim of this study was to develop a parent-metabolite population pharmacokinetic (PPK) model to quantify the effects of CYP2D6*10 allele on the pharmacokinetics of iloperidone and its metabolites in Chinese schizophrenia patients. METHODS Seventy Chinese schizophrenia patients were enrolled, from whom limited blood samples were collected on d 15 (0 h) and d 28 (0, 4 and 12 h after drug administration). The plasma concentrations of iloperidone and its metabolites M1 (P-88) and M2 (P-95) were simultaneously detected using a validated HPLC-MS assay. CYP2D6*10 (rs1065852) genotyping was performed. A PPK model was developed based on data from the patients using the NONMEM software (version 7.2). A one-compartment model with first-order absorption and elimination was used to describe the pharmacokinetic data related to iloperidone and its metabolites. RESULTS Patients with the CYP2D6*10 T/T genotype had significantly higher concentrations of iloperidone and M1, and lower concentrations of M2 than the patients with C/C or C/T genotypes. The CYP2D6*10 genotype affected the elimination constants for transformation of iloperidone to the metabolites M1 (K23) and M2 (K24). The K23 value of the patients with T/T genotype was 1.34-fold as great as that of the patients with C/C or C/T genotype. The K24 value of the patients with C/T and T/T genotypes was 0.693- and 0.492-fold, respectively, as low as that of the patients with C/C genotype. CONCLUSION CYP2D6*10 mutations affect the pharmacokinetics of iloperidone and its metabolites in Chinese schizophrenia patients, suggesting that the clinical doses of iloperidone for patients with CYP2D6*10 mutations need to be optimized.
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Borba MA, Melo-Neto RP, Leitão GM, Castelletti CH, Lima-Filho JL, Martins DB. Evaluating the impact of missenses mutations in CYP2D6*7 and CYP2D6*14A: does it compromise tamoxifen metabolism? Pharmacogenomics 2016; 17:573-82. [PMID: 27043475 DOI: 10.2217/pgs-2015-0003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED CYP2D6 is a high polymorphic enzyme from P450, responsible for metabolizing almost 25% of drugs. The distribution of different mutations among CYP2D6 alleles has been associated with poor, intermediate, extensive and ultra-metabolizers. AIM To evaluate how missenses mutations in CYP2D6*7 and CYP2D6*14A poor metabolizer alleles affect CYP2D6 stability and function. MATERIALS & METHODS CYPalleles database was used to collect polymorphisms data present in 105 alleles. We selected only poor metabolizers alleles that presented exclusively missenses mutations. They were analyzed through seven algorithms to predict the impact on CYP2D6 structure and function. RESULTS H324P, the unique mutation in CYP2D6*7, has high impact in enzyme function due to its occurrence between two alpha-helixes involved in active site dynamics. G169R, a mutation that occurs only in CYP2D6*14A, leads to the gain of solvent accessibility and severe protein destabilization. CONCLUSION Our in silico analysis showed that missenses mutations in CYP2D6*7 and CYP2D6*14A cause CYP2D6 dysfunction.
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Affiliation(s)
- Maria Acsm Borba
- Molecular Prospection and Bioinformatics Group (ProspecMol) - Laboratory of Immunopathology Keizo Asami (LIKA), Federal University of Pernambuco (UFPE), Av. Prof. Moraes Rego 1235, 50670-901, Cidade Universitária, Recife, PE, Brazil
| | - Renato P Melo-Neto
- Molecular Prospection and Bioinformatics Group (ProspecMol) - Laboratory of Immunopathology Keizo Asami (LIKA), Federal University of Pernambuco (UFPE), Av. Prof. Moraes Rego 1235, 50670-901, Cidade Universitária, Recife, PE, Brazil
| | - Glauber M Leitão
- Molecular Prospection and Bioinformatics Group (ProspecMol) - Laboratory of Immunopathology Keizo Asami (LIKA), Federal University of Pernambuco (UFPE), Av. Prof. Moraes Rego 1235, 50670-901, Cidade Universitária, Recife, PE, Brazil.,Clinical Hospital - Federal University of Pernambuco (UFPE), Av. Prof. Moraes Rego 1235, 50670-901, Cidade Universitária, Recife, PE, Brazil
| | - Carlos Hm Castelletti
- Molecular Prospection and Bioinformatics Group (ProspecMol) - Laboratory of Immunopathology Keizo Asami (LIKA), Federal University of Pernambuco (UFPE), Av. Prof. Moraes Rego 1235, 50670-901, Cidade Universitária, Recife, PE, Brazil.,Agronomic Institute of Pernambuco (IPA), Av. General San Martin 1371, 50761-000, Bongi, Recife, PE, Brazil
| | - José L Lima-Filho
- Biochemistry Department, Federal University of Pernambuco (UFPE), Av. Prof. Moraes Rego 1235, 50670-901, Cidade Universitária, Recife, PE, Brazil
| | - Danyelly Bg Martins
- Molecular Prospection and Bioinformatics Group (ProspecMol) - Laboratory of Immunopathology Keizo Asami (LIKA), Federal University of Pernambuco (UFPE), Av. Prof. Moraes Rego 1235, 50670-901, Cidade Universitária, Recife, PE, Brazil.,Biochemistry Department, Federal University of Pernambuco (UFPE), Av. Prof. Moraes Rego 1235, 50670-901, Cidade Universitária, Recife, PE, Brazil
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Luo X, Lei Y, He L, Liu W, Li M, Ran L, Yu M, Guo X, Yu P, Liu Z, Cheng Z. No influence of CYP2D6*10 genotype and phenotype on the pharmacokinetics of nebivolol in healthy Chinese subjects. J Clin Pharm Ther 2015. [PMID: 26214065 DOI: 10.1111/jcpt.12310] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
WHAT IS KNOWN AND OBJECTIVE Nebivolol, a clinically important antihypertensive drug, mainly metabolized by cytochrome P450 (CYP) 2D6, shows wide interindividual variability in pharmacokinetics. The CYP2D6*10 allele (100C>T; rs1065852), present at a high frequency in the Chinese population, is associated with alteration in the pharmacokinetics of many drugs, but its effect on the pharmacokinetics of nebivolol is unknown. The aim of our study was to investigate whether the CYP2D6*10 genotype and phenotype are associated with changes in the pharmacokinetics of nebivolol in Chinese subjects. METHODS Twenty-four healthy subjects were divided into three groups according to CYP2D6*1/*1 (n = 7), CYP2D6*1/*10 (n = 5) and CYP2D6*10/*10 (n = 12) genotypes. The *1/*1 homozygotes and *1/*10 heterozygotes were C allele carriers. All subjects received oral single dose of nebivolol and dextromethorphan. Blood and urine samples were gathered at various times. RESULTS There were no statistically significant differences in the pharmacokinetics of nebivolol between the three CYP2D6*10 genotypes, and no gene-dose effect was seen. The pharmacokinetic parameters of CYP2D6*10/*10 subjects were also similar to those of CYP2D6*1 carriers. A weak relationship between CYP2D6 phenotype and nebivolol clearance was found. WHAT IS NEW AND CONCLUSION The CYP2D6*10 genotype and phenotype were not associated with significant alterations in the pharmacokinetics of nebivolol. CYP2D6*10 alone does not account for the large interindividual differences observed in the disposition of nebivolol among Chinese healthy subjects.
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Affiliation(s)
- X Luo
- School of Life Sciences, Central South University, Changsha, China.,Research Institute of Drug Metabolism and Pharmacokinetics, School of Pharmaceutical Sciences, Central South University, Changsha, China
| | - Y Lei
- Research Institute of Drug Metabolism and Pharmacokinetics, School of Pharmaceutical Sciences, Central South University, Changsha, China.,Haikou People's Hospital and Affiliated Haikou Hospital of Xiangya Medical School, Central South University, Haikou, China
| | - L He
- Research Institute of Drug Metabolism and Pharmacokinetics, School of Pharmaceutical Sciences, Central South University, Changsha, China
| | - W Liu
- Research Institute of Drug Metabolism and Pharmacokinetics, School of Pharmaceutical Sciences, Central South University, Changsha, China
| | - M Li
- Research Institute of Drug Metabolism and Pharmacokinetics, School of Pharmaceutical Sciences, Central South University, Changsha, China
| | - L Ran
- Hunan Tiger Xiangya R&D Co., Ltd, Changsha, China
| | - M Yu
- Hunan Tiger Xiangya R&D Co., Ltd, Changsha, China
| | - X Guo
- Hunan Tiger Xiangya R&D Co., Ltd, Changsha, China
| | - P Yu
- Research Institute of Drug Metabolism and Pharmacokinetics, School of Pharmaceutical Sciences, Central South University, Changsha, China
| | - Z Liu
- Hunan Tiger Xiangya R&D Co., Ltd, Changsha, China
| | - Z Cheng
- Research Institute of Drug Metabolism and Pharmacokinetics, School of Pharmaceutical Sciences, Central South University, Changsha, China
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Abu-Elmagd M, Assidi M, Schulten HJ, Dallol A, Pushparaj PN, Ahmed F, Scherer SW, Al-Qahtani M. Individualized medicine enabled by genomics in Saudi Arabia. BMC Med Genomics 2015; 8 Suppl 1:S3. [PMID: 25951871 PMCID: PMC4315314 DOI: 10.1186/1755-8794-8-s1-s3] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The biomedical research sector in Saudi Arabia has recently received special attention from the government, which is currently supporting research aimed at improving the understanding and treatment of common diseases afflicting Saudi Arabian society. To build capacity for research and training, a number of centres of excellence were established in different areas of the country. Among these, is the Centre of Excellence in Genomic Medicine Research (CEGMR) at King Abdulaziz University, Jeddah, with its internationally ranked and highly productive team performing translational research in the area of individualized medicine. Here, we present a panorama of the recent trends in different areas of biomedical research in Saudi Arabia drawing from our vision of where genomics will have maximal impact in the Kingdom of Saudi Arabia. We describe advances in a number of research areas including; congenital malformations, infertility, consanguinity and pre-implantation genetic diagnosis, cancer and genomic classifications in Saudi Arabia, epigenetic explanations of idiopathic disease, and pharmacogenomics and personalized medicine. We conclude that CEGMR will continue to play a pivotal role in advances in the field of genomics and research in this area is facing a number of challenges including generating high quality control data from Saudi population and policies for using these data need to comply with the international set up.
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Affiliation(s)
- Muhammad Abu-Elmagd
- Centre of Excellence in Genomic Medicine Research (CEGMR), King Abdulaziz University, P.O. Box: 80216 Jeddah 21589, KSA
- KACST Technology Innovation Centre in Personalized Medicine at King Abdulaziz University (CIPM), P.O. Box: 80216 Jeddah 21589, KSA
- School of Biological Sciences, University of East Anglia, Norwich, Norfolk, NR4 7TJ, UK
- Zoology Department, Faculty of Science, Minia University, Minia, P.O. Box 61519, Egypt
| | - Mourad Assidi
- Centre of Excellence in Genomic Medicine Research (CEGMR), King Abdulaziz University, P.O. Box: 80216 Jeddah 21589, KSA
- KACST Technology Innovation Centre in Personalized Medicine at King Abdulaziz University (CIPM), P.O. Box: 80216 Jeddah 21589, KSA
| | - Hans-Juergen Schulten
- Centre of Excellence in Genomic Medicine Research (CEGMR), King Abdulaziz University, P.O. Box: 80216 Jeddah 21589, KSA
| | - Ashraf Dallol
- Centre of Excellence in Genomic Medicine Research (CEGMR), King Abdulaziz University, P.O. Box: 80216 Jeddah 21589, KSA
- KACST Technology Innovation Centre in Personalized Medicine at King Abdulaziz University (CIPM), P.O. Box: 80216 Jeddah 21589, KSA
| | - Peter Natesan Pushparaj
- Centre of Excellence in Genomic Medicine Research (CEGMR), King Abdulaziz University, P.O. Box: 80216 Jeddah 21589, KSA
| | - Farid Ahmed
- Centre of Excellence in Genomic Medicine Research (CEGMR), King Abdulaziz University, P.O. Box: 80216 Jeddah 21589, KSA
| | - Stephen W Scherer
- Centre of Excellence in Genomic Medicine Research (CEGMR), King Abdulaziz University, P.O. Box: 80216 Jeddah 21589, KSA
- The Centre for Applied Genomics and Program in Genetics and Genome Biology, the Hospital for Sick Children, Toronto, Ontario, Canada
- McLaughlin Centre and Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Mohammed Al-Qahtani
- Centre of Excellence in Genomic Medicine Research (CEGMR), King Abdulaziz University, P.O. Box: 80216 Jeddah 21589, KSA
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LLerena A, Naranjo MEG, Rodrigues-Soares F, Penas-LLedó EM, Fariñas H, Tarazona-Santos E. Interethnic variability ofCYP2D6alleles and of predicted and measured metabolic phenotypes across world populations. Expert Opin Drug Metab Toxicol 2014; 10:1569-83. [DOI: 10.1517/17425255.2014.964204] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Zahari Z, Ismail R. Influence of Cytochrome P450, Family 2, Subfamily D, Polypeptide 6 (CYP2D6) Polymorphisms on Pain Sensitivity and Clinical Response to Weak Opioid Analgesics. Drug Metab Pharmacokinet 2014; 29:29-43. [DOI: 10.2133/dmpk.dmpk-13-rv-032] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Chen B, Xu Y, Jiang T, Feng R, Sun J, Zhang W, Yang W, Li J, Adeniyi O, Chen H. Estimation of CYP2D6*10 genotypes on citalopram disposition in Chinese subjects by population pharmacokinetic assay. J Clin Pharm Ther 2013; 38:504-11. [PMID: 23981149 DOI: 10.1111/jcpt.12029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 10/25/2012] [Indexed: 11/26/2022]
Abstract
WHAT IS KNOWN AND OBJECTIVE There is great interindividual variability in citalopram (CIT) pharmacokinetics. We attempted to establish a population pharmacokinetic (PPK) model of CIT in Chinese healthy subjects, to evaluate the effect of genetic polymorphism on CIT pharmacokinetics and to compare the PPK and non-compartmental (NCA) assays in the estimation of CIT bioequivalence. METHODS Blood samples of 23 healthy subjects were collected after administration of CIT; plasma concentration of CIT was analysed using LC/MS-MS. CYP2C19 and CYP2D6*10 genotypes were determined. PPK model was established by using nonlinear mixed-effect modelling (NONMEM). The model was evaluated using goodness-of-fit plots and relative error measurements. Bioequivalence of CIT was evaluated by both PPK and NCA method. RESULTS AND DISCUSSION The estimated population absorption rate constant (ka ), clearance (CL/F) and volume of distribution (Vd/F) in Chinese healthy subjects are 0.64 L/h, 12.7 L/h and 705 L, respectively. Different CYP2C19 and CYP2D6 genotypes have impacts on CIT pharmacokinetics. There is about 5.5% decrement of CL/F for each CYP2C19*2 or CYP2D6*10 allele. The 90% confidence interval of CIT bioavailability obtained from NCA and PPK model were 96.4-105.4% and 92.5-103.4%, respectively. WHAT IS NEW AND CONCLUSION The PPK of CIT is best characterized by a one-compartment disposition model with first-order absorption. CYP2C19 and CYP2D6 genotypes have impacts on the CL/F of CIT. Bioequivalence of CIT can be estimated by both NCA and PPK model.
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Affiliation(s)
- B Chen
- Department of Pharmacy, Ruijin Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
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Chiba K, Kato M, Ito T, Suwa T, Sugiyama Y. Inter-individual Variability of In Vivo CYP2D6 Activity in Different Genotypes. Drug Metab Pharmacokinet 2012; 27:405-13. [DOI: 10.2133/dmpk.dmpk-11-rg-078] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Fleeman N, Dundar Y, Dickson R, Jorgensen A, Pushpakom S, McLeod C, Pirmohamed M, Walley T. Cytochrome P450 testing for prescribing antipsychotics in adults with schizophrenia: systematic review and meta-analyses. Pharmacogenomics J 2011; 11:1-14. [PMID: 20877299 DOI: 10.1038/tpj.2010.73] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
There is wide variability in the response of individuals to standard doses of antipsychotic drugs. It has been suggested that this may be partly explained by differences in the cytochrome P450 (CYP450) enzyme system responsible for metabolizing the drugs. We conducted a systematic review and meta-analyses to consider whether testing for CYP450 single nucleotide polymorphisms in adults starting antipsychotic treatment for schizophrenia predicts and leads to improvements in clinical outcomes. High analytic validity in terms of sensitivity and specificity was seen in studies reporting P450 testing. However, there was limited evidence of the role of CYP2D6 polymorphisms in antipsychotic efficacy, although there was an association between CYP2D6 genotype and extrapyramidal adverse effects. No studies reported on the prospective use of CYP2D6 genotyping tests in clinical practice. In conclusion, evidence of clinical validity and utility of CYP2D6 testing in patients being prescribed antipsychotics is lacking, and thus, routine pharmacogenetic testing prior to antipsychotic prescription cannot be supported at present. Further research is required to improve the evidence base and to generate data on clinical validity and clinical utility.
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Li Q, Wang R, Guo Y, Wen S, Xu L, Wang S. Relationship of CYP2D6 genetic polymorphisms and the pharmacokinetics of tramadol in Chinese volunteers. J Clin Pharm Ther 2009; 35:239-47. [DOI: 10.1111/j.1365-2710.2009.01102.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Abstract
Tamoxifen is the most widely used anti-oestrogen for the treatment of hormone-dependent breast cancer. The pharmacological activity of tamoxifen is dependent on its conversion by the hepatic drug-metabolizing enzyme cytochrome P450 2D6 (CYP2D6) to its abundant metabolite, endoxifen. Patients with reduced CYP2D6 activity, as a result of either their genotype or induction by the co-administration of drugs that inhibit CYP2D6 function, produce little endoxifen and seem to derive inferior therapeutic benefit from tamoxifen. Here we review the existing data that relate CYP2D6 genotypes to response to tamoxifen and discuss whether the analysis of the CYP2D6 genotype might be an early example of a pharmacogenetic tool for optimizing breast cancer therapy.
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Affiliation(s)
- Janelle M Hoskins
- UNC Institute for Pharmacogenomics and Individualized Therapy, Division of Pharmacotherapy and Experimental Therapeutics, University of North Carolina, Chapel Hill, 27599, North Carolina, USA
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Lee SJ, Lee SS, Jung HJ, Kim HS, Park SJ, Yeo CW, Shin JG. Discovery of Novel Functional Variants and Extensive Evaluation ofCYP2D6Genetic Polymorphisms in Koreans. Drug Metab Dispos 2009; 37:1464-70. [DOI: 10.1124/dmd.108.022368] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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