1
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Schoretsanitis G, Anıl Yağcıoğlu AE, Ruan CJ, Eap CB, Molden E, Baptista T, Clark SR, Fernandez-Egea E, Kim SH, Lane HY, Leung J, Maroñas Amigo O, Motuca M, Olmos I, Every-Palmer S, Procyshyn RM, Rohde C, Satish S, Schulte PFJ, Spina E, Takeuchi H, Verdoux H, Correll CU, de Leon J. Clozapine ultrarapid metabolism during weak induction probably exists but requires careful diagnosis. A literature review, five new cases and a proposed definition. Schizophr Res 2023:S0920-9964(23)00190-1. [PMID: 37268453 DOI: 10.1016/j.schres.2023.05.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 05/08/2023] [Accepted: 05/09/2023] [Indexed: 06/04/2023]
Abstract
During weak induction (from smoking and/or valproate co-prescription), clozapine ultrarapid metabolizers (UMs) need very high daily doses to reach the minimum therapeutic concentration of 350 ng/ml in plasma; clozapine UMs need clozapine doses higher than: 1) 900 mg/day in patients of European/African ancestry, or 2) 600 mg/day in those of Asian ancestry. Published clozapine UMs include 10 males of European/African ancestry, mainly assessed with single concentrations. Five new clozapine UMs (two of European and three of Asian ancestry) with repeated assessments are described. A US double-blind randomized trial included a 32-year-old male smoking two packages/day with a minimum therapeutic dose of 1,591 mg/day from a single TDM during open treatment of 900 mg/day. In a Turkish inpatient study, a 30-year-old male smoker was a possible clozapine UM needing a minimum therapeutic dose of 1,029 mg/day estimated from two trough steady-state concentrations on 600 mg/day. In a Chinese study, three possible clozapine UMs (all male smokers) were identified. The clozapine minimum therapeutic dose estimated with trough steady-state concentrations >150 ng/ml was: 1) 625 mg/day, based on a mean of 20 concentrations in Case 3; 2) 673 mg/day, based on a mean of 4 concentrations in Case 4; and 3) 648 mg/day, based on a mean of 11 concentrations in Case 5. Based on these limited studies, clozapine UMs during weak induction may account for 1-2% of clozapine-treated patients of European ancestry and <1% of those of Asian ancestry. A clozapine-to-norclozapine ratio <0.5 should not be used to identify clozapine UMs.
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Affiliation(s)
- Georgios Schoretsanitis
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital, University of Zürich, Zürich, Switzerland; Division of Psychiatry Research, Northwell Health, The Zucker Hillside Hospital, New York, NY, USA; Department of Psychiatry and Molecular Medicine, The Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, New York, NY, USA.
| | | | - Can-Jun Ruan
- The National Clinical Research Centre for Mental Disorders & Beijing Key Lab of Mental Disorders, Beijing Anding Hospital, Capital Medical University, Beijing, China; Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, China.
| | - Chin B Eap
- Unit of Pharmacogenetics and Clinical Psychopharmacology, Center for Psychiatric Neuroscience, Department of Psychiatry, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland; School of Pharmaceutical Sciences, University of Geneva, Geneva, Switzerland; Center for Research and Innovation in Clinical Pharmaceutical Sciences, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland; Institute of Pharmaceutical Sciences of Western Switzerland, University of Geneva, University of Lausanne, Geneva, Switzerland.
| | - Espen Molden
- Center for Psychopharmacology, Diakonhjemmet Hospital, PO Box 23 Vinderen, 0319 Oslo, Norway; Department of Pharmacy, University of Oslo, Oslo, Norway.
| | - Trino Baptista
- Department of Physiology, Los Andes University Medical School, Mérida, Venezuela; Medical School, Anáhuac University, Querétaro, Mexico; Neuroorigen, Querétaro, Mexico
| | - Scott R Clark
- University of Adelaide, Discipline of Psychiatry, Adelaide, Australia.
| | - Emilio Fernandez-Egea
- Department of Psychiatry, University of Cambridge, Cambridge, UK; Cambridgeshire and Peterborough NHS Foundation Trust, Fulbourn Hospital, Fulbourn, Cambridge, UK.
| | - Se Hyun Kim
- Department of Psychiatry, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea.
| | - Hsien-Yuan Lane
- Department of Psychiatry and Brain Disease Research Center, China Medical University Hospital, Taichung, Taiwan; Graduate Institute of Biomedical Sciences, China Medical University, Taichung, Taiwan; Department of Psychology, College of Medical and Health Sciences, Asia University, Taichung, Taiwan
| | - Jonathan Leung
- Department of Pharmacy, Mayo Clinic, Rochester, MN, USA.
| | - Olalla Maroñas Amigo
- Genomic Medicine Group, Galician Public Foundation of Genomic Medicine (FPGMX), Health Research Institute of Santiago de Compostela (IDIS), Santiago de Compostela, Galicia, Spain; Center for Research in Molecular Medicine and Chronic Diseases (CIMUS), University of Santiago de Compostela (USC), Santiago de Compostela, Spain; Center for Biomedical Research in Rare Diseases Network, Carlos III Health Institute, Madrid, Spain.
| | - Mariano Motuca
- Department of Psychiatry, School of Medicine at Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Ismael Olmos
- Clinical Pharmacology Unit, Pharmacy Department, Vilardebó Hospital, Administración de Servicios de Salud (ASSE), Montevideo, Uruguay.
| | - Susanna Every-Palmer
- Department of Psychological Medicine, University of Otago Wellington, Wellington, New Zealand.
| | - Ric M Procyshyn
- Department of Psychiatry, University of British Columbia, Vancouver, Canada; British Columbia Mental Health and Substance Use Services Research Institute, Vancouver, Canada.
| | - Christopher Rohde
- Department of Affective Disorders, Aarhus University Hospital - Psychiatry, Aarhus, Denmark; Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Suhas Satish
- Department of Psychiatry, National Institute of Mental Health and Neurosciences [NIMHANS], Bangalore, India
| | - Peter F J Schulte
- Mental Health Services Noord-Holland-Noord, Alkmaar, Netherlands; Dutch Clozapine Collaboration Group, Castricum, Netherlands.
| | - Edoardo Spina
- Department of Clinical and Experimental Medicine, University of Messina, Messina, Italy.
| | - Hiroyoshi Takeuchi
- Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan.
| | - Hélène Verdoux
- Université Bordeaux, Inserm, Bordeaux Population Health Research Center, Team Pharmacoepidemiology, UMR 1219, F-33000 Bordeaux, France.
| | - Christoph U Correll
- Division of Psychiatry Research, Northwell Health, The Zucker Hillside Hospital, New York, NY, USA; Department of Psychiatry and Molecular Medicine, The Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, New York, NY, USA; Department of Child and Adolescent Psychiatry, Charité Universitätsmedizin, Berlin, Germany.
| | - Jose de Leon
- Mental Health Research Center, Eastern State Hospital, Lexington, KY, USA; Biomedical Research Centre in Mental Health Net (CIBERSAM), Santiago Apóstol Hospital, University of the Basque Country, Vitoria, Spain.
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2
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Mostafa S, Polasek TM, Bousman C, Rostami‐Hodjegan A, Sheffield LJ, Everall I, Pantelis C, Kirkpatrick CMJ. Delineating gene-environment effects using virtual twins of patients treated with clozapine. CPT Pharmacometrics Syst Pharmacol 2022; 12:168-179. [PMID: 36424701 PMCID: PMC9931435 DOI: 10.1002/psp4.12886] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 10/11/2022] [Accepted: 10/13/2022] [Indexed: 11/27/2022] Open
Abstract
Studies that focus on individual covariates, while ignoring their interactions, may not be adequate for model-informed precision dosing (MIPD) in any given patient. Genetic variations that influence protein synthesis should be studied in conjunction with environmental covariates, such as cigarette smoking. The aim of this study was to build virtual twins (VTs) of real patients receiving clozapine with interacting covariates related to genetics and environment and to delineate the impact of interacting covariates on predicted clozapine plasma concentrations. Clozapine-treated patients with schizophrenia (N = 42) with observed clozapine plasma concentrations, demographic, environmental, and genotype data were used to construct VTs in Simcyp. The effect of increased covariate virtualization was assessed by performing simulations under three conditions: "low" (demographic), "medium" (demographic and environmental interaction), and "high" (demographic and environmental/genotype interaction) covariate virtualization. Increasing covariate virtualization with interaction improved the coefficient of variation (R2 ) from 0.07 in the low model to 0.391 and 0.368 in the medium and high models, respectively. Whereas R2 was similar between the medium and high models, the high covariate virtualization model had improved accuracy, with systematic bias of predicted clozapine plasma concentration improving from -138.48 ng/ml to -74.65 ng/ml. A high level of covariate virtualization (demographic, environmental, and genotype) may be required for MIPD using VTs.
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Affiliation(s)
- Sam Mostafa
- Centre for Medicine Use and SafetyMonash UniversityVictoriaParkvilleAustralia,MyDNA LifeAustralia LimitedVictoriaSouth YarraAustralia
| | - Thomas M. Polasek
- Centre for Medicine Use and SafetyMonash UniversityVictoriaParkvilleAustralia,CertaraNew JerseyPrincetonUSA,Department of Clinical PharmacologyRoyal Adelaide HospitalSouth AustraliaAdelaideAustralia
| | - Chad Bousman
- Melbourne Neuropsychiatry Centre, Department of PsychiatryUniversity of Melbourne & Melbourne HealthVictoriaMelbourneAustralia,The Cooperative Research Centre (CRC) for Mental HealthVictoriaMelbourneAustralia,Alberta Children's Hospital Research Institute, Cumming School of MedicineUniversity of CalgaryAlbertaCalgaryCanada,Hotchkiss Brain Institute, Cumming School of MedicineUniversity of CalgaryAlbertaCalgaryCanada,Departments of Medical Genetics, Psychiatry, and Physiology and PharmacologyUniversity of CalgaryAlbertaCalgaryCanada
| | - Amin Rostami‐Hodjegan
- Centre for Applied Pharmacokinetic Research (CAPKR), School of Health SciencesUniversity of ManchesterManchesterUK,Simcyp DivisionCertara UK LimitedSheffieldUK
| | | | - Ian Everall
- Melbourne Neuropsychiatry Centre, Department of PsychiatryUniversity of Melbourne & Melbourne HealthVictoriaMelbourneAustralia,The Cooperative Research Centre (CRC) for Mental HealthVictoriaMelbourneAustralia,Western Australian Health Translation NetworkNedlandsWestern AustraliaAustralia,Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneVictoriaMelbourneAustralia
| | - Christos Pantelis
- Melbourne Neuropsychiatry Centre, Department of PsychiatryUniversity of Melbourne & Melbourne HealthVictoriaMelbourneAustralia,The Cooperative Research Centre (CRC) for Mental HealthVictoriaMelbourneAustralia,Florey Institute of Neuroscience and Mental HealthUniversity of MelbourneVictoriaMelbourneAustralia
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3
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Mostafa S, Polasek TM, Bousman CA, Müeller DJ, Sheffield LJ, Rembach J, Kirkpatrick CM. Pharmacogenomics in psychiatry - the challenge of cytochrome P450 enzyme phenoconversion and solutions to assist precision dosing. Pharmacogenomics 2022; 23:857-867. [PMID: 36169629 DOI: 10.2217/pgs-2022-0104] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Pharmacogenomic (PGx) testing of cytochrome P450 (CYP) enzymes may improve the efficacy and/or safety of some medications. This is facilitated by increased availability and affordability of genotyping, the development of clinical practice PGx guidelines and regulatory support. However, the common occurrence of CYP phenoconversion, a mismatch between genotype-predicted CYP phenotype and the actual CYP phenotype, currently limits the application of PGx testing for precision dosing in psychiatry. This review proposes a stepwise approach to assist precision dosing in psychiatry via the introduction of PGx stewardship programs and innovative PGx education strategies. A future perspective on delivering precision dosing for psychiatrists is discussed that involves innovative clinical decision support systems powered by model-informed precision dosing.
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Affiliation(s)
- Sam Mostafa
- Centre for Medicine Use & Safety, Monash University, Parkville, Victoria, 3052, Australia.,MyDNA Life, Australia Limited, South Yarra, Victoria, Australia
| | - Thomas M Polasek
- Centre for Medicine Use & Safety, Monash University, Parkville, Victoria, 3052, Australia.,Certara, Princeton, NJ 08540, USA.,Department of Clinical Pharmacology, Royal Adelaide Hospital, Adelaide, South Australia, 5000, Australia
| | - Chad A Bousman
- Department of Psychiatry, Melbourne Neuropsychiatry Centre, University of Melbourne & Melbourne Health, Melbourne, Victoria, 3010, Australia.,The Cooperative Research Centre (CRC) for Mental Health, Carlton, Victoria, 3053, Australia.,Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 1N4, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 1N4, Canada.,Departments of Medical Genetics, Psychiatry, & Physiology & Pharmacology, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
| | - Daniel J Müeller
- Pharmacogenetics Research Clinic, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.,Department of Psychiatry, University of Toronto, Toronto, Ontario, M5T 1R8, Canada
| | | | - Joel Rembach
- MyDNA Life, Australia Limited, South Yarra, Victoria, Australia
| | - Carl Mj Kirkpatrick
- Centre for Medicine Use & Safety, Monash University, Parkville, Victoria, 3052, Australia
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4
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Pandey A, Kalita KN. Treatment-resistant schizophrenia: How far have we traveled? Front Psychiatry 2022; 13:994425. [PMID: 36111312 PMCID: PMC9468267 DOI: 10.3389/fpsyt.2022.994425] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 08/09/2022] [Indexed: 11/13/2022] Open
Abstract
Treatment-resistant schizophrenia is a lack of adequate response to antipsychotic medications resulting in incomplete functional and social recovery from the illness. Different definitions have been proposed for clinical practice and research work. Antipsychotics that are used in the management of schizophrenia mainly act on multiple dopaminergic pathways which are implicated in the development of symptoms of schizophrenia. Newer antipsychotics also are implicated to affect the serotonergic pathways. Clozapine is the only evidence-based treatment available for the management of treatment-resistant cases. Neurobiologically, there is a considerable overlap between treatment-resistant and treatment-responsive cases. The factors that are implicated in the evolution of treatment resistance are still not conclusive. These make the management of such patients a challenge. However, certain peculiarities of treatment-resistant schizophrenia have been identified which can guide us in the early identification and precise treatment of the treatment-resistant cases.
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Affiliation(s)
- Ambu Pandey
- Department of Psychiatry, Maharshi Devraha Baba Autonomous State Medical College, Deoria, India
| | - Kamal Narayan Kalita
- Department of Psychiatry, Lokpriya Gopinath Bordoloi Regional Institute of Mental Health, Tezpur, India
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5
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Jürgens G. The Utility of Pharmacogenetics Testing in Psychiatric Populations. J Pers Med 2021; 11:jpm11121262. [PMID: 34945734 PMCID: PMC8708570 DOI: 10.3390/jpm11121262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 11/22/2021] [Indexed: 11/16/2022] Open
Abstract
The implementation of pharmacogenetic tests including multiple gene variants has shown promising potential as a decision-making tool for optimizing psychopharmacological treatment regimens and reducing treatment costs. However, the varying clinical validity of gene variants included in pharmacogenetic test batteries, and inconsistencies in their translation into medical recommendations between commercially available pharmacogenetic tests, complicates their rational implementation. Thus, there is a need for well-designed, reproducible studies documenting the clinical significance of the various genetic variants.
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Affiliation(s)
- Gesche Jürgens
- Clinical Pharmacology Unit, Zealand University Hospital, DK-4000 Roskilde, Denmark
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6
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Clinical and genetic influencing factors on clozapine pharmacokinetics in Tunisian schizophrenic patients. THE PHARMACOGENOMICS JOURNAL 2021; 21:551-558. [PMID: 33731885 DOI: 10.1038/s41397-021-00231-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 02/04/2021] [Accepted: 02/22/2021] [Indexed: 02/02/2023]
Abstract
Clozapine (Clz) is an atypical antipsychotic, which its pharmacokinetics can be influenced by several factors. The CYP1A2 and CYP2C19, major enzymes implicated in Clz metabolism, present an interethnic variation on their activity caused by single nucleotide polymorphisms (SNPs). The present study investigated the influence of genetic and nongenetic factors on Clz pharmacokinetics in a southern Mediterranean population. We included adult Tunisian schizophrenic patients having received Clz and undergone a therapeutic drug monitoring (TDM) of Clz by morning C0 monitoring. The genomic DNA was extracted using a salting-out procedure. CYP1A2*1F (rs762551;-163C>A), CYP1A2*1C (rs2069514;-3860 G>A) and CYP 2C19*2 (rs4244285; 681G>A) was analyzed using PCR-RFLP. Fifty-one patients were enrolled in the study. The mutant allele (CYP1A2*1F) was the most frequently detected (58.8%). For CYP1A2*1F, Clz dose-normalized (C0/D ratio) was as high as 1.28 ± 0.37 in CC versus 0.67 ± 0.32 ng mL-1 per mg day-1 in AA group (p < 0.001). The influence of genetic (CYP1A2*1F, CYP1A2*1C and CYP2C19*2) and nongenetic parameters (age, weight, gender, tobacco, coffee, and alcohol consumption) on the variation of the Clz C0/D ratio was investigated. Only the CYP1A2*1 F polymorphism correlates significantly with the Clz C0/D variation and could explain 24% of its variability. Our data support a critical role of the CYP1A2 -163C>A on the variation of Clz exposure in Tunisian schizophrenic patients. Considering its narrow therapeutic range, CYP1A2 genotyping combined with TDM of Clz may improve efficacy and safety of this drug. Further studies are needed to investigate this issue.
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7
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Islam F, Maciukiewicz M, Freeman N, Huang E, Tiwari A, Mulsant BH, Pollock BG, Remington G, Kennedy JL, Müller DJ, Rajji TK. Contributions of cholinergic receptor muscarinic 1 and CYP1A2 gene variants on the effects of plasma ratio of clozapine/N-desmethylclozapine on working memory in schizophrenia. J Psychopharmacol 2021; 35:31-39. [PMID: 33143542 DOI: 10.1177/0269881120946288] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Clozapine has heterogenous efficacy in enhancing working memory in schizophrenia. We have previously hypothesized that this is due to opposing effects of clozapine and its metabolite, N-desmethylclozapine, at the muscarinic M1 receptor and demonstrated that a lower clozapine/N-desmethylclozapine ratio is associated with better working memory than clozapine or N-desmethylclozapine levels alone. AIMS In this study, we expanded the above hypothesis to explore whether genetic variation in the cholinergic receptor muscarinic 1 gene, encoding the M1 receptor, affects the relationship between clozapine/N-desmethylclozapine and working memory. Further, we explored whether CYP1A2 gene variants affect the ratio of clozapine/N-desmethylclozapine and by this, working memory performance. METHODS We evaluated two functionally significant single nucleotide polymorphisms, rs1942499 and rs2075748, in cholinergic receptor muscarinic 1, with the haplotype T-A associated with lower transcriptional activity than the haplotype C-G. Further, we examined CYP1A2 *1F, with *1F/*1F conferring high inducibility in the presence of smoking. RESULTS In a sample of 30 patients with schizophrenia on clozapine monotherapy, clozapine/N-desmethylclozapine was correlated with working memory only in non-carriers of the haplotype T-A of the cholinergic receptor muscarinic 1 gene. Interaction of CYP1A2 genotype and smoking status significantly affected clozapine concentrations, but there were no significant effects of CYP1A2 genotype and smoking status on the relationship between clozapine/N-desmethylclozapine on working memory. CONCLUSIONS Our finding that the relationship between clozapine/N-desmethylclozapine and working memory is specific to patients with potentially higher transcription of M1 receptor (i.e. non-carriers of the haplotype T-A of cholinergic receptor muscarinic 1) supports a cholinergic mechanism underlying this relationship.
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Affiliation(s)
- Farhana Islam
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada.,Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada
| | - Malgorzata Maciukiewicz
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada
| | - Natalie Freeman
- Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, Canada
| | - Eric Huang
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada
| | - Arun Tiwari
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada
| | - Benoit H Mulsant
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada.,Department of Psychiatry, University of Toronto, Toronto, Canada.,Adult Neurodevelopment and Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Toronto, Canada
| | - Bruce G Pollock
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada.,Department of Psychiatry, University of Toronto, Toronto, Canada.,Adult Neurodevelopment and Geriatric Psychiatry Division, Centre for Addiction and Mental Health, Toronto, Canada
| | - Gary Remington
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada.,Department of Psychiatry, University of Toronto, Toronto, Canada
| | - James L Kennedy
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada.,Department of Psychiatry, University of Toronto, Toronto, Canada
| | - Daniel J Müller
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada.,Department of Pharmacology and Toxicology, University of Toronto, Toronto, Canada.,Department of Psychiatry, University of Toronto, Toronto, Canada
| | - Tarek K Rajji
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Canada.,Krembil Centre for Neuroinformatics, Centre for Addiction and Mental Health, Toronto, Canada.,Department of Psychiatry, University of Toronto, Toronto, Canada
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8
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Li Z, Lee SH, Jeong HJ, Kang HE. Pharmacokinetic changes of clozapine and norclozapine in a rat model of non-alcoholic fatty liver disease induced by orotic acid. Xenobiotica 2020; 51:324-334. [PMID: 33185134 DOI: 10.1080/00498254.2020.1851070] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Impaired in vitro oxidation of clozapine has been reported in steatotic rat liver due to downregulation of cytochrome P450 (CYP) 1A. Pharmacokinetic changes of clozapine and its major metabolite, norclozapine, were evaluated in a rat model of non-alcoholic fatty liver disease (NAFLD) induced by orotic acid. Significantly slower in vitro CLint for formation of norclozapine from clozapine was observed in NAFLD rats than in control rats as a result of the reduced protein expression and metabolic activity of CYP1A1/2. However, systemic exposures to clozapine in NAFLD rats were comparable to those in controls after intravenous (4 mg/kg) and oral (10 mg/kg) administration of clozapine. Of note, the AUC of the norclozapine and AUCnorclozapine/AUCclozapine ratio following intravenous and oral administration of clozapine rather increased significantly in NAFLD rats, as a result of the slowed subsequent metabolism of norclozapine via CYP1A1/2. Steady-state brain concentrations of both clozapine and norclozapine were significantly higher in NAFLD rats than those in control rats following intravenous infusion of clozapine. Increased systemic exposure to norclozapine and elevated brain concentrations of clozapine and norclozapine observed in NAFLD rats imply that further studies are warranted on the pharmacotherapy of clozapine in patients with pre-existing or drug-induced hepatic steatosis.
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Affiliation(s)
- Zhengri Li
- College of Pharmacy and Integrated Research Institute of Pharmaceutical Sciences, The Catholic University of Korea, Bucheon, South Korea
| | - Song Hee Lee
- College of Pharmacy and Integrated Research Institute of Pharmaceutical Sciences, The Catholic University of Korea, Bucheon, South Korea
| | - Hee Jin Jeong
- College of Pharmacy and Integrated Research Institute of Pharmaceutical Sciences, The Catholic University of Korea, Bucheon, South Korea
| | - Hee Eun Kang
- College of Pharmacy and Integrated Research Institute of Pharmaceutical Sciences, The Catholic University of Korea, Bucheon, South Korea
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9
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Ruan CJ, de Leon J. Is there a future for CYP1A2 pharmacogenetics in the optimal dosing of clozapine? Pharmacogenomics 2020; 21:369-373. [PMID: 32308139 DOI: 10.2217/pgs-2020-0015] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
- Can-Jun Ruan
- Laboratory of Clinical Psychopharmacology & The National Clinical Research Center for Mental Disorders & Beijing Key Lab of Mental Disorders, Beijing Anding Hospital, Capital Medical University, Beijing, China
| | - Jose de Leon
- Mental Health Research Center, Eastern State Hospital, Lexington, KY 40511, USA.,Psychiatry & Neurosciences Research Group (CTS-549), Institute of Neurosciences, University of Granada, Granada, Spain.,Biomedical Research Centre in Mental Health Net (CIBERSAM), Santiago Apóstol Hospital, University of the Basque Country, Vitoria, Spain
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10
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Jovanović M, Vučićević K, Miljković B. Understanding variability in the pharmacokinetics of atypical antipsychotics - focus on clozapine, olanzapine and aripiprazole population models. Drug Metab Rev 2020; 52:1-18. [PMID: 32008418 DOI: 10.1080/03602532.2020.1717517] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Antipsychotic medicines are widely used for the management of psychotic symptoms regardless of the underlying diagnosis. Most atypical antipsychotics undergo extensive metabolism prior to excretion. Various factors may influence their pharmacokinetics, particularly elimination, leading to highly variable drug concentrations between individual patients following the same dosing regimen. Population pharmacokinetic approach, based on nonlinear mixed effects modeling, is a useful tool to identify covariates explaining pharmacokinetic variability, as well as to characterize and distinguish unexplained residual and between-subject (interindividual) variability. In addition, this approach allows the use of both sparsely and intensively sampled data. In this paper, we reviewed the pharmacokinetic characteristics of clozapine, olanzapine and aripiprazole, focusing on a population modeling approach. In particular, models based on a nonlinear mixed effects approach performed by NONMEM® software in order to identify and quantify sources of pharmacokinetic variability are presented. Population models were identified through systematic searches of PubMed and sixteen studies were selected. Some of the factors identified that significantly contribute to variability in elimination among clozapine, olanzapine, and aripiprazole are demographic characteristics, body weight, genetic polymorphism, smoking and in some cases drug interactions. Scientific research based on pharmacometric modeling is useful to further characterize sources of variability and their combined effect.
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Affiliation(s)
- Marija Jovanović
- Department of Pharmacokinetics and Clinical Pharmacy, University of Belgrade - Faculty of Pharmacy, Belgrade, Republic of Serbia
| | - Katarina Vučićević
- Department of Pharmacokinetics and Clinical Pharmacy, University of Belgrade - Faculty of Pharmacy, Belgrade, Republic of Serbia
| | - Branislava Miljković
- Department of Pharmacokinetics and Clinical Pharmacy, University of Belgrade - Faculty of Pharmacy, Belgrade, Republic of Serbia
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11
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Clozapine Metabolism in East Asians and Caucasians: A Pilot Exploration of the Prevalence of Poor Metabolizers and a Systematic Review. J Clin Psychopharmacol 2019; 39:135-144. [PMID: 30811372 DOI: 10.1097/jcp.0000000000001018] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE/BACKGROUND In clozapine therapeutic drug monitoring (TDM) studies, Chinese reached the same concentrations using half the dosage Caucasians use. Defining clozapine poor metabolizers (PMs) requires stratification by ethnicity, smoking, and sex. METHODS/PROCEDURES After sex and smoking stratification in 129 Chinese inpatients (mean, 8.8 TDM samples per patient), we explored the association between the total concentration-dose (C/D) ratio and CYP1A2 (*1C, *1F, and *7) and CYP2C19 alleles (*2 and *3). A systematic literature review identified 22 clozapine TDM prior studies (13 in Caucasians and 7 in East Asians). FINDINGS/RESULTS In our Chinese sample, the mean total clozapine C/D ratio (ng/mL per mg/d) was 1.96 for 22 male smokers, 2.07 for 5 female smokers, 2.47 for 36 male nonsmokers, and 2.95 for 66 female nonsmokers. CYP1A2 *1C had no significant effects, and CYP1A2 *1F had small effects. Five clozapine PMs (4%) needed low clozapine doses of 75 to 115 mg/d to get therapeutic concentrations. Using the same methodology in a published Italian sample, we found 5 PMs (3.3% of 152). In the systematic review, the clozapine C/D ratio (ng/mL per mg/d) was higher when comparing: (1) weighted mean values of 1.57 in 876 East Asians versus 1.07 in 1147 Caucasians and (2) ranks of 8 East Asians versus 13 Caucasian samples (P < 0.001). IMPLICATIONS/CONCLUSIONS Future TDM studies need to further explore the frequency of clozapine PMs after sex and smoking stratification in East Asian and Caucasian patients. Compared with Caucasians, East Asians appear to have a clinically relevant decrease in clozapine clearance.
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Na Takuathung M, Hanprasertpong N, Teekachunhatean S, Koonrungsesomboon N. Impact of CYP1A2 genetic polymorphisms on pharmacokinetics of antipsychotic drugs: a systematic review and meta-analysis. Acta Psychiatr Scand 2019; 139:15-25. [PMID: 30112761 DOI: 10.1111/acps.12947] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/16/2018] [Indexed: 12/23/2022]
Abstract
OBJECTIVE To determine the impact of CYP1A2 genetic polymorphisms on the pharmacokinetics of CYP1A2-metabolized antipsychotic drugs in humans by means of systematic review and meta-analysis. METHOD A systematic search was conducted in PubMed and Scopus databases as of June 26, 2018. Studies reporting the pharmacokinetic parameters of CYP1A2-metabolized antipsychotic drugs in individuals who were genotyped for CYP1A2 genetic polymorphisms were retrieved. Pharmacokinetic parameters of individuals who have mutant alleles of a CYP1A2 genetic polymorphism were compared with the wild-type individuals. Pooled-effect estimates, presented as standardized mean difference, were calculated by means of the fixed-effect or random-effects model, as appropriate. RESULTS Ten studies involving 872 clozapine users, seven studies involving 712 olanzapine users, and two studies involving 141 haloperidol users were included. All but one study reported no associations between any CYP1A2 genetic polymorphisms and the pharmacokinetics of CYP1A2-metabolized antipsychotic drugs. The pooled-effect estimates through meta-analyses of seven studies demonstrated no significant associations between the -163C>A or -2467delT polymorphism and clozapine or olanzapine concentrations in the blood. CONCLUSIONS This study suggests that CYP1A2 genetic polymorphisms have no significant impact on the pharmacokinetics of CYP1A2-metabolized antipsychotic drugs. CYP1A2 genotyping may have no clinical implications for personalized dosing of CYP1A2-metabolized antipsychotic drugs.
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Affiliation(s)
- M Na Takuathung
- Department of Pharmacology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - N Hanprasertpong
- Department of Pharmacology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - S Teekachunhatean
- Department of Pharmacology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.,Center of Thai Traditional and Complementary Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - N Koonrungsesomboon
- Department of Pharmacology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
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Storelli F, Samer C, Reny JL, Desmeules J, Daali Y. Complex Drug-Drug-Gene-Disease Interactions Involving Cytochromes P450: Systematic Review of Published Case Reports and Clinical Perspectives. Clin Pharmacokinet 2018; 57:1267-1293. [PMID: 29667038 DOI: 10.1007/s40262-018-0650-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Drug pharmacokinetics (PK) is influenced by multiple intrinsic and extrinsic factors, among which concomitant medications are responsible for drug-drug interactions (DDIs) that may have a clinical relevance, resulting in adverse drug reactions or reduced efficacy. The addition of intrinsic factors affecting cytochromes P450 (CYPs) activity and/or expression, such as genetic polymorphisms and diseases, may potentiate the impact and clinical relevance of DDIs. In addition, greater variability in drug levels and exposures has been observed when such intrinsic factors are present in addition to concomitant medications perpetrating DDIs. This variability results in poor predictability of DDIs and potentially dramatic clinical consequences. The present review illustrates the issue of complex DDIs using systematically searched published case reports of DDIs involving genetic polymorphisms, renal impairment, cirrhosis, and/or inflammation. Current knowledge on the impact of each of these factors on drug exposure and DDIs is summarized and future perspectives for the management of such complex DDIs in clinical practice are discussed, including the use of advanced Computerized Physician Order Entry (CPOE) systems, the development of model-based dose optimization strategies, and the education of healthcare professionals with respect to personalized medicine.
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Affiliation(s)
- Flavia Storelli
- Division of Clinical Pharmacology and Toxicology, Geneva University Hospitals, University of Geneva, Geneva, Switzerland
- Geneva-Lausanne School of Pharmacy, University of Geneva, Geneva, Switzerland
| | - Caroline Samer
- Division of Clinical Pharmacology and Toxicology, Geneva University Hospitals, University of Geneva, Geneva, Switzerland
- Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Swiss Center for Applied Human Toxicology, Geneva, Switzerland
| | - Jean-Luc Reny
- Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Department of Internal Medicine, Rehabilitation and Geriatrics, Geneva University Hospitals, University of Geneva, Geneva, Switzerland
| | - Jules Desmeules
- Division of Clinical Pharmacology and Toxicology, Geneva University Hospitals, University of Geneva, Geneva, Switzerland
- Geneva-Lausanne School of Pharmacy, University of Geneva, Geneva, Switzerland
- Faculty of Medicine, University of Geneva, Geneva, Switzerland
- Swiss Center for Applied Human Toxicology, Geneva, Switzerland
| | - Youssef Daali
- Division of Clinical Pharmacology and Toxicology, Geneva University Hospitals, University of Geneva, Geneva, Switzerland.
- Geneva-Lausanne School of Pharmacy, University of Geneva, Geneva, Switzerland.
- Faculty of Medicine, University of Geneva, Geneva, Switzerland.
- Swiss Center for Applied Human Toxicology, Geneva, Switzerland.
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Chopra N, Ruan CJ, McCollum B, Ognibene J, Shelton C, de Leon J. High Doses of Drugs Extensively Metabolized by CYP3A4 Were Needed to Reach Therapeutic Concentrations in Two Patients Taking Inducers. ACTA ACUST UNITED AC 2018; 49:84-95. [PMID: 32446424 DOI: 10.1016/j.rcp.2018.07.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 07/04/2018] [Indexed: 12/18/2022]
Abstract
INTRODUCTION In the last 20 years of clinical practice, the senior author has identified these 2 rare cases in which the patients needed extremely high doses of drugs metabolized by CYP3A4 to reach and maintain serum therapeutic concentrations. METHODS The high metabolic ability of these 2 patients was demonstrated by the low concentration-to-dose ratios (C/D ratios) of several drugs metabolized by CYP3A4. RESULTS Case 1 was characterized by a history of high carbamazepine doses (up to 2,000mg/day) and needed 170 mg/day of diazepam in 2 days to cooperate with dental cleaning. The high activity of the CYP3A4 isoenzyme was manifested by fast metabolism for quetiapine and diazepam, which took more than 1 year to normalize after the inducer, phenytoin, was stopped. Case 2 was also very sensitive to CYP3A4 inducers as indicated by very low C/D ratios for carbamazepine, risperidone and paliperidone. The carbamazepine (2,800 mg/day) and risperidone (20 mg/day) dosages for this second patient are the highest doses ever seen for these drugs by the senior author. Risperidone induction appeared to last for many months and metabolism was definitively normal 3 years after stopping carbamazepine. On the other hand, olanzapine C/D ratios were normal for induction. CONCLUSIONS The literature has never described similar cases of very high doses of drugs metabolized by CYP3A4. We speculate that these 2 patients may have unusual genetic profiles at the nuclear receptor levels; these receptors regulate induction of drugs.
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Affiliation(s)
- Nitin Chopra
- Addictions Division, Centre for Addiction and Mental Health, Toronto, Canada
| | - Can-Jun Ruan
- Laboratory of Clinical Psychopharmacology, Beijing Key Lab of Mental Disorders, Beijing Anding Hospital, Capital Medical University, Beijing, China
| | | | - Judy Ognibene
- Apalachee, Inc., Eastside Psychiatric Hospital, Tallahassee, Florida, USA
| | | | - Jose de Leon
- University of Kentucky Mental Health Research Center, Eastern State Hospital, Lexington, Kentucky, USA; Psychiatry and Neurosciences Research Group (CTS-549), Institute of Neurosciences, University of Granada, Granada, Spain; Biomedical Research Centre in Mental Health Net (CIBERSAM), Santiago Apostol Hospital, University of the Basque Country, Vitoria, Álava, Spain.
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Murray M, Zhang WV, Edwards RJ. Variation in the Response of Clozapine Biotransformation Pathways in Human Hepatic Microsomes to CYP1A2- and CYP3A4-selective Inhibitors. Basic Clin Pharmacol Toxicol 2017; 122:388-395. [PMID: 29155491 DOI: 10.1111/bcpt.12933] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 10/27/2017] [Indexed: 01/17/2023]
Abstract
The atypical antipsychotic agent clozapine (CLZ) is effective in many patients who are resistant to conventional antipsychotic drugs. Cytochromes P450 (CYPs) 1A2 and 3A4 oxidize CLZ to norCLZ and CLZ N-oxide in human liver. Concurrent treatment with inducers and inhibitors of CYP1A2 modulates CLZ elimination that disrupts therapy. Drug-drug interactions involving CYP3A4 are also significant but less predictable. To further characterize the factors underlying these interactions, we used samples from a cohort of human livers to assess variation in CLZ oxidation pathways in relation to intrinsic CYP3A4 and CYP1A2 activities and the effects of the corresponding selective inhibitors ketoconazole (0.2 and 2 μM) and fluvoxamine (1 and 10 μM). The CYP3A4-selective inhibitor ketoconazole (2 μM) impaired CLZ N-oxide formation in all 14 of the livers used in inhibition studies (≥50% inhibition) while the CYP1A2-selective inhibitor fluvoxamine (10 μM) decreased norCLZ formation in nine. Ketoconazole effectively inhibited CLZ metabolism in five of seven livers that catalysed CYP3A4-dependent testosterone 6β-hydroxylation at or above the median rate and in four other livers with lower intrinsic CYP3A4 activity. Similarly, fluvoxamine (10 μM) readily inhibited CLZ oxidation in seven livers with high CYP1A2-mediated 7-ethoxyresorufin O-deethylation activity (at or above the median) and three livers with lower intrinsic CYP1A2 activity. In three livers, CLZ biotransformation was impaired by both ketoconazole and fluvoxamine, consistent with a major role for both CYPs. These findings suggest that the intrinsic activities of CYPs 1A2 and 3A4 are unrelated to the response to CYP-selective inhibitors and that assessment of the activities in vivo may not assist the prediction of drug-drug interactions.
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Affiliation(s)
- Michael Murray
- Pharmacogenomics and Drug Development Group, Discipline of Pharmacology, School of Medical Sciences, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Wei V Zhang
- Pharmacogenomics and Drug Development Group, Discipline of Pharmacology, School of Medical Sciences, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Robert J Edwards
- Centre for Pharmacology and Therapeutics, Imperial College London, London, UK
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Cigarette smoking has a differential effect on the plasma level of clozapine in Taiwanese schizophrenic patients associated with the CYP1A2 gene -163A/C single nucleotide polymorphism. Psychiatr Genet 2017; 26:172-7. [PMID: 27203225 DOI: 10.1097/ypg.0000000000000139] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
OBJECTIVE The efficacy of clozapine clearance has been shown to be associated with smoking and genetic polymorphism of CYP1A2. This study aims to investigate the effect of smoking on the plasma level of clozapine in Taiwanese schizophrenic patients and its relevance to the CYP1A2 gene -163A/C single nucleotide polymorphism. MATERIALS AND METHODS A total of 143 hospitalized schizophrenic patients who had received clozapine therapy for at least 14 days were enrolled in this study. The trough plasma concentration of clozapine was measured with LC/MS/MS. The -163A/C variant in the CYP1A2 gene was identified by DNA sequencing and restriction fragment length polymorphism analysis. The effect of smoking on the clozapine level was examined by multiple linear regression analysis and its relation to the -163A/C variant of the CYP1A2 gene was analyzed using a general linear model with Bonferroni correction. RESULTS Patients with smoking habits showed a significantly lower plasma level of clozapine than those without smoking habits (P=0.022) and the difference in clozapine levels between smokers and nonsmokers appeared to be significant in the individuals carrying the homozygous -163A allele (P=0.02). It was also found that nonsmokers carrying the -163A allele tended to have higher plasma levels of clozapine. This tendency was not found in the individuals with smoking habits. CONCLUSION Cigarette smoking has a significant impact on the plasma level of clozapine in Taiwanese schizophrenic patients carrying the homozygous -163A allele in the CYP1A2 gene. Cigarette smoking may increase the clearance of clozapine in these patients.
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Eum S, Lee AM, Bishop JR. Pharmacogenetic tests for antipsychotic medications: clinical implications and considerations. DIALOGUES IN CLINICAL NEUROSCIENCE 2017. [PMID: 27757066 PMCID: PMC5067149 DOI: 10.31887/dcns.2016.18.3/jbishop] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Optimizing antipsychotic pharmacotherapy is often challenging due to significant variability in effectiveness and tolerability. Genetic factors influencing pharmacokinetics and pharmacodynamics may contribute to some of this variability. Research studies have characterized these pharmacogenetic relationships, and some genetic markers are now available as clinical tests. These advances in pharmacogenetics research and test availability have great potential to improve clinical outcomes and quality of life in psychiatric patients. For clinicians considering using pharmacogenetics, it is important to understand the clinical implications and also the limitations of markers included in currently available tests. This review focuses on pharmacokinetic and pharmacodynamic gene variants that are currently available in commercial genetic testing panels. Associations of these variants with clinical efficacy and adverse effects, as well as other clinical implications, in antipsychotic pharmacotherapy are discussed.
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Affiliation(s)
- Seenae Eum
- College of Pharmacy, Department of Experimental and Clinical Pharmacology; University of Minnesota, Minneapolis, Minnesota, USA
| | - Adam M Lee
- College of Pharmacy, Department of Experimental and Clinical Pharmacology; University of Minnesota, Minneapolis, Minnesota, USA
| | - Jeffrey R Bishop
- College of Pharmacy, Department of Experimental and Clinical Pharmacology; College of Medicine, Department of Psychiatry; University of Minnesota, Minneapolis, Minnesota, USA
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Adehin A, Bolaji OO, Maggo S, Kennedy MA. Relationship between metabolic phenotypes and genotypes of CYP1A2 and CYP2A6 in the Nigerian population. Drug Metab Pers Ther 2017; 32:39-47. [PMID: 28231062 DOI: 10.1515/dmpt-2016-0041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 01/23/2017] [Indexed: 11/15/2022]
Abstract
BACKGROUND CYP1A2 and CYP2A6 are polymorphic drug-metabolising enzymes that are also implicated in the activation of procarcinogens in humans. Some of their alleles and haplotypes, often varied in prevalence across populations, are thought to influence activity despite the known contribution of environmental factors. This study assessed the potential influence of some genetic variants of CYP1A2 and CYP2A6 on metabolic phenotypes in Nigerians. METHODS Genomic DNA was extracted from blood samples of 100 healthy, unrelated subjects for whom CYP1A2 and CYP2A6 phenotypes had previously been determined, alongside an additional 80 other individuals for whom phenotype data were unavailable. The samples were screened for CYP1A2 (*1C,*1D,*1E,*1F, *3,*4,*6,*7) and CYP2A6 (*9,*11,*17) alleles using the Sequenom MassARRAY platform for some alleles and direct Sanger sequencing for others. The genetic data acquired were subsequently analysed for haplotypes and assessed for concordance with phenotypes. RESULTS All five CYP1A2 haplotypes (CYP1A2*1F, 1J, 1N, 1L, 1W) identified in the Nigerian population were not significantly predictive of metabolic phenotypes. Heterozygous CYP1A2*1J carriers and homozygous CYP1A2*1W carriers showed statistically insignificant decrease in CYP1A2 activity. The CYP2A6*9/*17 genotype was, however, significantly associated with the CYP2A6-poor metabolic phenotype, whereas CYP2A6*9 or CYP2A6*17 alone did not show any such association. CYP2A6*11 was not detected in the population. CONCLUSIONS Our findings suggest that CYP1A2 alleles or haplotypes were not predictive of metabolic phenotypes in the Nigerian population. Carriers of CYP2A6*9/*17 genotype are likely to be poor metabolisers of CYP2A6 substrates and may experience adverse reactions or poor efficacy while using drugs metabolised mainly by CYP2A6.
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Balibey H, Basoglu C, Lundgren S, Babaoglu MO, Yasar U, Herken H, Rane A, Bozkurt A, Cetin M. CYP1A2*1F Polymorphism Decreases Clinical Response to Clozapine in Patients with Schizophrenia. ACTA ACUST UNITED AC 2016. [DOI: 10.5455/bcp.20110622071701] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
| | | | - Stefan Lundgren
- Karolinska Institutet, Department of Laboratory Medicine, Division of Clinical Pharmacology, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Melih O. Babaoglu
- Department of Pharmacology, Faculty of Medicine, Hacettepe University, Ankara-Turkey
| | - Umit Yasar
- Department of Pharmacology, Faculty of Medicine, Hacettepe University, Ankara-Turkey
| | - Hasan Herken
- Department of Psychiatry, Pamukkale University, Denizli-Turkey
| | - Anders Rane
- Karolinska Institutet, Department of Laboratory Medicine, Division of Clinical Pharmacology, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Atilla Bozkurt
- Department of Pharmacology, Faculty of Medicine, Hacettepe University, Ankara-Turkey
| | - Mesut Cetin
- Department of Psychiatry, GATA, Istanbul-Turkey
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Lally J, Gaughran F, Timms P, Curran SR. Treatment-resistant schizophrenia: current insights on the pharmacogenomics of antipsychotics. Pharmgenomics Pers Med 2016; 9:117-129. [PMID: 27853387 PMCID: PMC5106233 DOI: 10.2147/pgpm.s115741] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Up to 30% of people with schizophrenia do not respond to two (or more) trials of dopaminergic antipsychotics. They are said to have treatment-resistant schizophrenia (TRS). Clozapine is still the only effective treatment for TRS, although it is underused in clinical practice. Initial use is delayed, it can be hard for patients to tolerate, and clinicians can be uncertain as to when to use it. What if, at the start of treatment, we could identify those patients likely to respond to clozapine - and those likely to suffer adverse effects? It is likely that clinicians would feel less inhibited about using it, allowing clozapine to be used earlier and more appropriately. Genetic testing holds out the tantalizing possibility of being able to do just this, and hence the vital importance of pharmacogenomic studies. These can potentially identify genetic markers for both tolerance of and vulnerability to clozapine. We aim to summarize progress so far, possible clinical applications, limitations to the evidence, and problems in applying these findings to the management of TRS. Pharmacogenomic studies of clozapine response and tolerability have produced conflicting results. These are due, at least in part, to significant differences in the patient groups studied. The use of clinical pharmacogenomic testing - to personalize clozapine treatment and identify patients at high risk of treatment failure or of adverse events - has moved closer over the last 20 years. However, to develop such testing that could be used clinically will require larger, multicenter, prospective studies.
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Affiliation(s)
- John Lally
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
- Department of Psychiatry, Royal College of Surgeons in Ireland, Beaumont Hospital, Dublin, Ireland
- National Psychosis Service
| | - Fiona Gaughran
- Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK
- National Psychosis Service
| | - Philip Timms
- START Team, South London and Maudsley NHS Foundation Trust
- King’s College London
| | - Sarah R Curran
- King’s College London
- South West London and St George’s Mental Health NHS Foundation Trust
- St George’s University of London, London, UK
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The clinical potentials of adjunctive fluvoxamine to clozapine treatment: a systematic review. Psychopharmacology (Berl) 2016; 233:741-50. [PMID: 26626327 DOI: 10.1007/s00213-015-4161-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 10/24/2015] [Indexed: 10/22/2022]
Abstract
RATIONALE New clozapine optimization strategies are warranted, as some patients do not achieve sufficient response and experience various adverse effects. Fluvoxamine is a potent CYP1A2 inhibitor and may increase the ratio of clozapine to its primary metabolite N-desmethylclozapine (NDMC). OBJECTIVES This study aims to review all pharmacodynamic effects and the adverse effect profile of changing the clozapine/NDMC ratio with adjunctive fluvoxamine. METHODS MEDLINE, Embase, and the Cochrane Library were searched with the search terms "clozapine" and "fluvoxamine" without any time limit. Language was restricted to English, Scandinavian, Polish, and German. Studies were sorted for relevance based on title and abstract. Clinical recommendations of potential indications/effects were graded as level A, B, C, or D depending on studies of high, moderate, low, or very low quality, respectively. RESULTS Based on data from 24 case reports/series, seven cohort studies, and two randomized controlled trials, 241 patients were studied. Evidence (A) supported that adjunctive fluvoxamine increased clozapine plasma levels. This may increase the probability of response in patients, where sufficient clozapine plasma levels cannot be achieved. Adjunctive fluvoxamine reduced metabolic adverse effects of clozapine (B) but not agranulocytosis risk (B). Although depressive or obsessive-compulsive symptoms may improve, a SSRI with no CYP1A2 inhibition should rather be used (C). No studies investigated the effect of adjunctive fluvoxamine to minimize clozapine rebound psychosis (D) or to reduce the effects of smoking on clozapine plasma levels (D). CONCLUSIONS Adjunctive fluvoxamine may have clinical potentials for optimizing clozapine treatment but further clinical studies are warranted to explore the clinical implications.
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de Brito RB, de Carvalho Araújo L, Diniz MJA, de Castro Georg R, Nabout JC, Vianelo RP, da Silva Santos R, da Silva Cruz AH, Ghedini PC. The CYP1A2 -163C > A polymorphism is associated with super-refractory schizophrenia. Schizophr Res 2015; 169:502-503. [PMID: 26530626 DOI: 10.1016/j.schres.2015.10.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 10/04/2015] [Accepted: 10/09/2015] [Indexed: 11/30/2022]
Affiliation(s)
- Rodrigo Bernini de Brito
- Post-Graduate Program in Biological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, GO, Brazil; Brain Institute, Bueno Medical Center, Goiânia, GO, Brazil
| | | | | | - Raphaela de Castro Georg
- Post-Graduate Program in Biological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, GO, Brazil
| | | | - Rosana Pereira Vianelo
- Post-Graduate Program in Biological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, GO, Brazil
| | - Rodrigo da Silva Santos
- Post-Graduate Program in Biological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, GO, Brazil
| | - Aline Helena da Silva Cruz
- Post-Graduate Program in Biological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, GO, Brazil
| | - Paulo César Ghedini
- Post-Graduate Program in Biological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, GO, Brazil.
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Hu J, Shang D, Xu X, He X, Ni X, Zhang M, Wang Z, Qiu C, Deng S, Lu H, Zhu X, Huang W, Wen Y. Effect of grapefruit juice and food on the pharmacokinetics of pirfenidone in healthy Chinese volunteers: a diet-drug interaction study. Xenobiotica 2015; 46:516-21. [PMID: 26407124 DOI: 10.3109/00498254.2015.1089365] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
1. Ingestion of grapefruit juice and food could be factors affecting the pharmacokinetics of pirfenidone, a promising drug for treatment of idiopathic pulmonary fibrosis. 2. A randomized, open-label, three-period crossover study was carried out in 12 healthy Chinese male volunteers who were randomized to one of the three treatments: pirfenidone tablets (0.4 g) were orally administered to fasted or fed subjects, or with grapefruit juice. The washout period was 7 d. 3. Significantly reduced maximum plasma concentration (Cmax, 5.0 5 ± 1.39 versus 10.9 0 ± 2.94 mg·L(- 1)), modestly affected area-under-the-plasma concentration-time curve (AUC) from time zero to 12 h post dosing (AUC0-12 h, 21.8 9 ± 6.47 versus 26.1 6 ± 7.32 mg·h·L(- 1)) and delayed time to reach Cmax (Tmax) were observed in fed group compared with fasted group. Similar effects on Cmax (5.8 2 ± 1.23 versus 10.9 0 ± 2.94 mg·L(- 1)) and AUC0-12 h (modest but not statistically significant, 24.4 4 ± 7.40 versus 26.1 6 ± 7.32 mg·h·L(- 1)) were observed for grapefruit juice compared to fasted subjects. 4. Co-administration of pirfenidone with grapefruit juice resulted in modestly reduced overall oral absorption and significantly reduced peak concentrations compared to fasting, which was similar to effect of food ingestion. No adverse events were observed in the study, but relatively dramatic reduction of peak concentrations should raise concerns for clinical efficacy and safety.
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Affiliation(s)
- Jinqing Hu
- a Institution of National Drug Clinical Trials, Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University) , Guangzhou , China
| | - Dewei Shang
- a Institution of National Drug Clinical Trials, Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University) , Guangzhou , China
| | - Xinwen Xu
- b Ebang Pharmaceutical Co. Ltd , Zhuhai , China , and
| | - Xiuling He
- a Institution of National Drug Clinical Trials, Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University) , Guangzhou , China .,c Department of Pharmacy , Xinhui People's Hospital of Jiangmen , Jiangmen , China
| | - Xiaojia Ni
- a Institution of National Drug Clinical Trials, Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University) , Guangzhou , China
| | - Ming Zhang
- a Institution of National Drug Clinical Trials, Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University) , Guangzhou , China
| | - Zhanzhang Wang
- a Institution of National Drug Clinical Trials, Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University) , Guangzhou , China
| | - Chang Qiu
- a Institution of National Drug Clinical Trials, Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University) , Guangzhou , China
| | - Shuhua Deng
- a Institution of National Drug Clinical Trials, Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University) , Guangzhou , China
| | - Haoyang Lu
- a Institution of National Drug Clinical Trials, Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University) , Guangzhou , China
| | - Xiuqing Zhu
- a Institution of National Drug Clinical Trials, Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University) , Guangzhou , China
| | - Wencan Huang
- a Institution of National Drug Clinical Trials, Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University) , Guangzhou , China
| | - Yuguan Wen
- a Institution of National Drug Clinical Trials, Guangzhou Brain Hospital (Guangzhou Huiai Hospital, the Affiliated Brain Hospital of Guangzhou Medical University) , Guangzhou , China
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Geng T, Zhang XY, Wang L, Wang H, Shi X, Kang L, Hou P, Jin T. Genetic polymorphism analysis of the drug-metabolizing enzyme CYP1A2 in a Uyghur Chinese population: a pilot study. Xenobiotica 2015; 46:542-7. [PMID: 26383175 DOI: 10.3109/00498254.2015.1089367] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
1. CYP1A2 is a highly polymorphic gene and CYP1A2 enzyme results in broad inter-individual variability in response to certain pharmacotherapies, while little is known about the genetic variation of CYP1A2 in Uyghur Chinese population. The aim of the present study was to screen Uyghur volunteers for CYP1A2 genetic polymorphisms. 2. We used DNA sequencing to investigate promoter, exons, introns, and 3' UTR of the CYP1A2 gene in 96 unrelated healthy Uyghur individuals. We also used SIFT (Sorting Intolerant From Tolerant) and PolyPhen-2 (Polymorphism Phenotyping v2) to predict the protein function of the novel non-synonymous mutation in CYP1A2 coding regions. 3. We identified 20 different CYP1A2 polymorphisms in the Uyghur Chinese population, including two novel variants (119A > G and 2410G > A). Variant 119A > G was predicted to be probably damaging on protein function by PolyPhen-2, by contrast, 2410G > A was identified as benign. The allele frequencies of CYP1A2*1A, *1B, *1F, *1G, *1J, *1M, *4, and *9 were 23.4%, 53.1%, 3.7%, 2.6%, 2.6%, 13.5%, 0.5%, and 0.5%, respectively. The frequency of *1F, a putative high inducibility allele, was higher in our sample population compared with that in the Caucasian population (p < 0.05). The most common genotype combinations were *1A/*1B (46.9%) and *1B/*1M (27.1%). 4. Our results provide basic information on CYP1A2 polymorphisms in Uyghur individuals and suggest that the enzymatic activities of CYP1A2 may differ among the diverse ethnic populations of the world.
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Affiliation(s)
- Tingting Geng
- a National Engineering Research Center for Miniaturized Detection Systems, School of Life Sciences, Northwest University , Xi'an , Shaanxi , China .,b Department of Endocrinology , School of Medicine, the First Affiliated Hospital of Xi'an Jiaotong University , Xi'an , China .,c Department of Obstetrics, Gynecology, and Reproductive Sciences , School of Medicine, Yale University , New Haven , CT , USA , and
| | - Xi Yang Zhang
- a National Engineering Research Center for Miniaturized Detection Systems, School of Life Sciences, Northwest University , Xi'an , Shaanxi , China
| | - Li Wang
- d Key Laboratory for Molecular Genetic Mechanisms and Intervention Research on High Altitude Disease of Tibet Autonomous Region, School of Medicine, Xizang Minzu University , Xianyang , Shaanxi , China
| | - Huijuan Wang
- a National Engineering Research Center for Miniaturized Detection Systems, School of Life Sciences, Northwest University , Xi'an , Shaanxi , China
| | - Xugang Shi
- a National Engineering Research Center for Miniaturized Detection Systems, School of Life Sciences, Northwest University , Xi'an , Shaanxi , China
| | - Longli Kang
- d Key Laboratory for Molecular Genetic Mechanisms and Intervention Research on High Altitude Disease of Tibet Autonomous Region, School of Medicine, Xizang Minzu University , Xianyang , Shaanxi , China
| | - Peng Hou
- a National Engineering Research Center for Miniaturized Detection Systems, School of Life Sciences, Northwest University , Xi'an , Shaanxi , China
| | - Tianbo Jin
- a National Engineering Research Center for Miniaturized Detection Systems, School of Life Sciences, Northwest University , Xi'an , Shaanxi , China .,d Key Laboratory for Molecular Genetic Mechanisms and Intervention Research on High Altitude Disease of Tibet Autonomous Region, School of Medicine, Xizang Minzu University , Xianyang , Shaanxi , China
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Genetic variation in melatonin pathway enzymes in children with autism spectrum disorder and comorbid sleep onset delay. J Autism Dev Disord 2015; 45:100-10. [PMID: 25059483 DOI: 10.1007/s10803-014-2197-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Sleep disruption is common in individuals with autism spectrum disorder (ASD). Genes whose products regulate endogenous melatonin modify sleep patterns and have been implicated in ASD. Genetic factors likely contribute to comorbid expression of sleep disorders in ASD. We studied a clinically unique ASD subgroup, consisting solely of children with comorbid expression of sleep onset delay. We evaluated variation in two melatonin pathway genes, acetylserotonin O-methyltransferase (ASMT) and cytochrome P450 1A2 (CYP1A2). We observed higher frequencies than currently reported (p < 0.04) for variants evidenced to decrease ASMT expression and related to decreased CYP1A2 enzyme activity (p ≤ 0.0007). We detected a relationship between genotypes in ASMT and CYP1A2 (r(2) = 0.63). Our results indicate that expression of sleep onset delay relates to melatonin pathway genes.
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Szalai R, Magyari L, Matyas P, Duga B, Banfai Z, Szabo A, Kovesdi E, Melegh B. Genetic polymorphisms in promoter and intronic regions of CYP1A2 gene in Roma and Hungarian population samples. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2014; 38:814-820. [PMID: 25461540 DOI: 10.1016/j.etap.2014.09.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 09/12/2014] [Accepted: 09/21/2014] [Indexed: 06/04/2023]
Abstract
The purpose of this study was to determine the interethnic differences of four CYP1A2 drug metabolizing enzyme variants. A total of 404 Roma and 396 Hungarian healthy subjects were genotyped for -163C>A, -729C>T, -2467delT and -3860G>A variants of CYP1A2 by RT-PCR and PCR-RFLP technique. The -3860A and -729T allele were not detectable in Roma samples, while in Hungarian samples were present with 2.02% and 0.25% prevalence, respectively. There was a 1.5-fold difference in presence of homozygous -163AA genotype between Hungarian and Roma samples (49.5% vs. 31.9%, p<0.001). The -163A allele frequency was 68.6% in Hungarians and 56.9% in Romas (p=0.025). The -2467delT allele frequency was 6.81% in Roma group and 5.81% in Hungarians. The most frequent allelic constellation was -3860G/-2467T/-729C/-163A in both populations. In conclusion, Hungarians have markedly elevated chance for rapid metabolism of CYP1A2 substrates, intensified procarcinogen activation and increased risk for cancers.
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Affiliation(s)
- Renata Szalai
- Department of Medical Genetics, Clinical Center, University of Pecs, Szigeti 12, H-7624 Pecs, Hungary; Szentagothai Research Centre, University of Pecs, Ifjusag 20, H-7624 Pecs, Hungary.
| | - Lili Magyari
- Department of Medical Genetics, Clinical Center, University of Pecs, Szigeti 12, H-7624 Pecs, Hungary; Szentagothai Research Centre, University of Pecs, Ifjusag 20, H-7624 Pecs, Hungary.
| | - Petra Matyas
- Department of Medical Genetics, Clinical Center, University of Pecs, Szigeti 12, H-7624 Pecs, Hungary.
| | - Balazs Duga
- Department of Medical Genetics, Clinical Center, University of Pecs, Szigeti 12, H-7624 Pecs, Hungary; Szentagothai Research Centre, University of Pecs, Ifjusag 20, H-7624 Pecs, Hungary.
| | - Zsolt Banfai
- Department of Medical Genetics, Clinical Center, University of Pecs, Szigeti 12, H-7624 Pecs, Hungary.
| | - Andras Szabo
- Department of Medical Genetics, Clinical Center, University of Pecs, Szigeti 12, H-7624 Pecs, Hungary.
| | - Erzsebet Kovesdi
- Department of Medical Genetics, Clinical Center, University of Pecs, Szigeti 12, H-7624 Pecs, Hungary; Szentagothai Research Centre, University of Pecs, Ifjusag 20, H-7624 Pecs, Hungary.
| | - Bela Melegh
- Department of Medical Genetics, Clinical Center, University of Pecs, Szigeti 12, H-7624 Pecs, Hungary; Szentagothai Research Centre, University of Pecs, Ifjusag 20, H-7624 Pecs, Hungary.
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Spina E, de Leon J. Clinical applications of CYP genotyping in psychiatry. J Neural Transm (Vienna) 2014; 122:5-28. [DOI: 10.1007/s00702-014-1300-5] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 08/18/2014] [Indexed: 12/13/2022]
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Viikki M, Kampman O, Seppälä N, Mononen N, Lehtimäki T, Leinonen E. CYP1A2 polymorphism -1545C > T (rs2470890) is associated with increased side effects to clozapine. BMC Psychiatry 2014; 14:50. [PMID: 24555493 PMCID: PMC3937243 DOI: 10.1186/1471-244x-14-50] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Accepted: 02/13/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cytochrome P450 1A2 gene (CYP1A2) polymorphisms have been suggested to be associated with increased side effects to antipsychotics. However, studies on this are scarce and have been conducted with either various antipsychotics or only in small samples of patients receiving clozapine. The aim of the present study was to test for an association between the CYP1A2 -1545C > T (rs2470890) polymorphism and side effects in a larger sample of patients during long-term clozapine treatment. METHODS A total of 237 patients receiving clozapine treatment completed the Liverpool University Neuroleptic Side-Effect Rating Scale (LUNSERS) assessing clozapine-induced side effects. Of these patients, 180 completed the questionnaire satisfactorily, agreed to provide a blood sample, and were successfully genotyped for the polymorphism. RESULTS The TT genotype of CYP1A2 polymorphism -1545C > T (rs2470890) was associated with significantly more severe side effects during clozapine treatment (p = 0.011). In a subanalysis, all seven types of side effects (sympathicotonia-tension; depression-anxiety; sedation; orthostatic hypotension; dermal side effects; urinary side effects; and sexual side effects) appeared numerically (but insignificantly) more severely among TT carriers. In addition, use of mood stabilizers was more common among patients with the TT genotype (OR = 2.63, p = 0.004). CONCLUSIONS This study has identified an association between the CYP1A2 polymorphism -1545C > T (rs2470890) and the occurrence of more severe clozapine side effects. However, these results should be regarded as tentative and more studies of larger sample sizes will be required to confirm the result.
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Affiliation(s)
- Merja Viikki
- University of Tampere, Medical School, University of Tampere, Tampere 33014, Finland.
| | - Olli Kampman
- University of Tampere, Medical School, University of Tampere, Tampere 33014, Finland,Seinäjoki Hospital District, Department of Psychiatry, Seinäjoki, Finland
| | - Niko Seppälä
- Department of Psychiatry, Satakunta Hospital District, Fi-28500, Pori, Finland
| | - Nina Mononen
- Department of Clinical Chemistry, Fimlab Laboratories, School of Medicine University of Tampere, Tampere, Finland
| | - Terho Lehtimäki
- Department of Clinical Chemistry, Fimlab Laboratories, School of Medicine University of Tampere, Tampere, Finland
| | - Esa Leinonen
- University of Tampere, Medical School, University of Tampere, Tampere 33014, Finland,Department of Psychiatry, Tampere University Hospital, Tampere, Finland
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Brandl EJ, Kennedy JL, Müller DJ. Pharmacogenetics of antipsychotics. CANADIAN JOURNAL OF PSYCHIATRY. REVUE CANADIENNE DE PSYCHIATRIE 2014; 59:76-88. [PMID: 24881126 PMCID: PMC4079237 DOI: 10.1177/070674371405900203] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
OBJECTIVE During the past decades, increasing efforts have been invested in studies to unravel the influence of genetic factors on antipsychotic (AP) dosage, treatment response, and occurrence of adverse effects. These studies aimed to improve clinical care by predicting outcome of treatment with APs and thus allowing for individualized treatment strategies. We highlight most important findings obtained through both candidate gene and genome-wide association studies, including pharmacokinetic and pharmacodynamic factors. METHODS We reviewed studies on pharmacogenetics of AP response and adverse effects published on PubMed until early 2012. Owing to the high number of published studies, we focused our review on findings that have been replicated in independent studies or are supported by meta-analyses. RESULTS Most robust findings were reported for associations between polymorphisms of the cytochrome P450 system, the dopamine and the serotonin transmitter systems, and dosage, treatment response, and adverse effects, such as AP-induced weight gain or tardive dyskinesia. These associations were either detected for specific medications or for classes of APs. CONCLUSION First promising and robust results show that pharmacogenetics bear promise for a widespread use in future clinical practice. This will likely be achieved by developing algorithms that will include many genetic variants. However, further investigation is warranted to replicate and validate previous findings, as well as to identify new genetic variants involved in AP response and for replication of existing findings.
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Affiliation(s)
- Eva J Brandl
- Postdoctoral Research Fellow, Neurogenetics Section, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario
| | - James L Kennedy
- Head, Neurogenetics Section, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health (CAMH), Toronto, Ontario; Director, Neuroscience Research Department, Neuroscience Department, CAMH, Toronto, Ontario; l'Anson Professor of Psychiatry and Medical Science, University of Toronto, Toronto, Ontario
| | - Daniel J Müller
- Head, Pharmacogenetics Research Clinic, Neurogenetics Section, Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, Ontario; Associate Professor, University of Toronto, Toronto, Ontario
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Arranz MJ, Munro JC. Toward understanding genetic risk for differential antipsychotic response in individuals with schizophrenia. Expert Rev Clin Pharmacol 2014; 4:389-405. [DOI: 10.1586/ecp.11.16] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
Pediatric behavioral and affective disorders often require antipsychotic therapy, in combination with psychotherapeutic interventions, for their treatment and stabilization. Although pharmacotherapy can include either typical or atypical antipsychotics, the latter are generally preferred because of their apparently lower risk of adverse effects. Recent controlled trials have demonstrated the efficacy of some of these agents (including aripiprazole, clozapine, olanzapine, paliperidone, quetiapine, risperidone, ziprasidone) in adolescent schizophrenia and children or adolescent bipolar mania, or to treat severe aggression and self-injury in the context of autism in children and adolescents. Although few studies have systematically monitored their short- and, more importantly, long-term safety, current evidence indicates that sedation, hyperprolactinemia, and metabolic abnormalities such as excess weight gain, diabetes, and related cardiovascular effects were clinically relevant adverse effects in young patients, with the individual agents differing in their propensity to induce these effects. When prescribing antipsychotics for children and adolescents, physicians should therefore be aware of the specific adverse effect profiles and patients should be closely monitored for the short- and long-term development of adverse events. In pediatric patients, the starting dose, titration plan, and maintenance dose of antipsychotics must be based on their pharmacokinetics and metabolism, as in adults. Because there are significant individual differences in drug and active metabolite(s) pharmacokinetics and metabolism, which may be further affected by a number of confounding factors (including demographic variables, phenotype and drug interactions), therapeutic drug monitoring may be a valid tool for individualizing dosage, but its interpretation should also take account of changes in pharmacodynamic sensitivity with the development during childhood and adolescence.
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Affiliation(s)
- Silvio Caccia
- Istituto di Ricerche Farmacologiche IRCCS-Mario Negri, via Giuseppe La Masa 19, 20156 Milan, Italy.
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Wang CY, Zhang ZJ, Li WB, Zhai YM, Cai ZJ, Weng YZ, Zhu RH, Zhao JP, Zhou HH. The Differential Effects of Steady-State Fluvoxamine on the Pharmacokinetics of Olanzapine and Clozapine in Healthy Volunteers. J Clin Pharmacol 2013; 44:785-92. [PMID: 15199083 DOI: 10.1177/0091270004266621] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The combination of atypical antipsychotics and selective serotonin reuptake inhibitors is an effective strategy in the treatment of certain psychiatric disorders. However, pharmacokinetic interactions between the two classes of drugs remain to be explored. The present study was designed to determine whether there were different effects of steady-state fluvoxamine on the pharmacokinetics of a single dose of olanzapine and clozapine in healthy male volunteers. One single dose of 10 mg olanzapine (n = 12) or clozapine (n = 9) was administered orally. Following a drug washout of at least 4 weeks, all subjects received fluvoxamine (100 mg/day) for 9 days, and one single dose of 10 mg olanzapine or clozapine was added on day 4. Plasma concentrations of olanzapine, clozapine, and N-desmethylclozapine were assayed at serial time points after the antipsychotics were given alone and when added to fluvoxamine. No bioequivalence was found in olanzapine alone and cotreatment with fluvoxamine for the mean peak plasma concentration (C(max)), the area under the concentration-time curve from time 0 to last sampling time point (AUC(0-t)), and from time 0 to infinity (AUC(0- infinity )). Under the cotreatment, C(max) of olanzapine was significantly elevated by 49%, with a 32% reduced time (t(max)) to C(max), whereas the C(max) and t(max) of clozapine were unaltered. The cotreatment increased the AUC(0-t) and AUC(0- infinity ) of olanzapine by 68% and 76%, respectively, greater than those of clozapine (40% and 41%). The presence of fluvoxamine also prolonged the elimination half-life (t(1/2)) of olanzapine by 40% and, to a much greater extent, clozapine by 370% but reduced the total body clearance (CL/F) of clozapine (78%) more significantly than it did for olanzapine (42%). The apparent volume of distribution (V(d)) was suppressed by 31% in olanzapine combined with fluvoxamine but was unaltered in the clozapine regimen. A significant reduction in the N-desmethylclozapine to clozapine ratio was present in the clozapine with fluvoxamine regimen. The effects of fluvoxamine on different aspects of pharmacokinetics of the two antipsychotics may have implications for clinical therapeutics.
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Affiliation(s)
- Chuan-Yue Wang
- Laboratory of Clinical Psychopharmacology, Beijing An Ding Hospital, Capital University of Medical Sciences, 5 Ankang Hutong Road, Xicheng District, Beijing 100088, China
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Rajkumar AP, Poonkuzhali B, Kuruvilla A, Srivastava A, Jacob M, Jacob KS. Association between CYP1A2 gene single nucleotide polymorphisms and clinical responses to clozapine in patients with treatment-resistant schizophrenia. Acta Neuropsychiatr 2013; 25:2-11. [PMID: 26953068 DOI: 10.1111/j.1601-5215.2012.00638.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVES Despite clozapine's superior clinical efficacy in treatment-resistant schizophrenia (TRS), its adverse effects, need for periodic leukocyte monitoring, cost and variable clinical outcomes mandate a clinical need to predict its treatment response. Although cytochrome P450 1A2 (CYP1A2) is the principal determinant of metabolism of clozapine, the role of CYP1A2 gene in the clinical response to clozapine is uncertain. Hence, we investigated its association with treatment responses and adverse events of clozapine in TRS. METHODS We evaluated four single nucleotide polymorphisms (SNP) in the CYP1A2 gene, clinical responses and serum clozapine levels in 101 consecutive patients with TRS on stable doses of clozapine. We defined clozapine response a priori and investigated allelic and genotypic associations. We assessed the socio-demographic and clinical profiles, premorbid adjustment, traumatic life events, cognition and disability of the participants, using standard assessment schedules for appropriate multivariate analyses. RESULTS Our results revealed that CYP1A2 gene SNP (*1C, *1D, *1E and *1F) were not associated with clozapine treatment response, adverse effects, serum clozapine levels or with disability (p values > 0.10). CONCLUSION As CYP1A2 gene SNP do not help to predict the clinical response to clozapine, routine screening for them prior to start clozapine is currently unwarranted. We suggest future longitudinal genome-wide association studies investigating clinical and pharmacogenetic variables together.
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Affiliation(s)
- Anto P Rajkumar
- 1 Department of Psychiatry, Christian Medical College, Vellore 632002, India
| | - B Poonkuzhali
- 3 Department of Haematology, Christian Medical College, Vellore 632002, India
| | - Anju Kuruvilla
- 1 Department of Psychiatry, Christian Medical College, Vellore 632002, India
| | - Alok Srivastava
- 3 Department of Haematology, Christian Medical College, Vellore 632002, India
| | - Molly Jacob
- 4 Department of Biochemistry, Christian Medical College, Vellore 632002, India
| | - K S Jacob
- 1 Department of Psychiatry, Christian Medical College, Vellore 632002, India
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Ferrari M, Bolla E, Bortolaso P, Callegari C, Poloni N, Lecchini S, Vender S, Marino F, Cosentino M. Association between CYP1A2 polymorphisms and clozapine-induced adverse reactions in patients with schizophrenia. Psychiatry Res 2012; 200:1014-7. [PMID: 22901441 DOI: 10.1016/j.psychres.2012.07.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 07/01/2012] [Accepted: 07/04/2012] [Indexed: 11/16/2022]
Abstract
We investigated the relationships between common polymorphisms in CYP1A2 (CYP1A2(⁎)1C and (⁎)1F), CYP1A2-mRNA levels in circulating lymphocytes and clozapine(CLZ)-induced adverse drug reactions (ADRs) in 34 patients. Patients with ADRs had a higher frequency of CYP1A2 low activity allele combinations (8/12; 67%) and lower CYP1A2-mRNA levels than patients without ADRs (6/22; 27%, P=0.019).
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Affiliation(s)
- Marco Ferrari
- Department of Clinical Medicine- Section Clinical and Experimental Pharmacology, University of Insubria, Via Otorino Rossi 9, 21100 Varese, Italy
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Ropinirole as an effective adjunctive treatment for clozapine-resistant negative symptoms in simple schizophrenia: a case report. J Clin Psychopharmacol 2012; 32:719-20. [PMID: 22926612 DOI: 10.1097/jcp.0b013e318267062c] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Murray M. Cytochromes P450: Roles in the Biotransformation of Chemicals in Cigarette Smoke and Impact of Smoking Cessation on Concurrent Drug Therapy. J Smok Cessat 2012. [DOI: 10.1375/jsc.5.2.107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
AbstractCigarette smoke contains polycyclic aromatic hydrocarbons (PAHs) that activate the expression of cytochrome P450 family 1 (CYP1) enzymes in liver and other tissues; this process is dependent on the aryl hydrocarbon receptor (AhR) transcription factor. An important CYP1 enzyme, CYP1A2, has a critical role in the oxidation of drugs such as clozapine, olanzapine and theophylline; these drugs exhibit a high incidence of adverse effects that are linked to plasma concentrations. This article reviews the impact of smoking and smoking cessation on therapy with toxic drugs that undergo CYP-mediated elimination. PAHs in cigarette smoke activate the AhR and upregulate CYP1A2, which enhances the clearance of these drugs, diminishes their efficacy and necessitates the use of higher doses. However, smoking cessation decreases PAH exposure, which leads to a decline in clearance of CYP1A2 substrate drugs. Dose reductions and close therapeutic monitoring for such drugs are recommended in patients who cease smoking.
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Ketoconazole-associated preferential increase in dopamine D2 receptor occupancy in striatum compared to pituitary in vivo: role for drug transporters? J Clin Psychopharmacol 2012; 32:110-3. [PMID: 22198458 DOI: 10.1097/jcp.0b013e3182408fc8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Membrane transporters such as P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) are efflux pumps that remove drugs from the brain back to the peripheral blood compartment, serving as a functional component of the blood-brain barrier (BBB). We report here that coadministration of the P-gp and BCRP inhibitor ketoconazole with risperidone may preferentially increase D2 receptor occupancy in the striatum compared to pituitary. Four male patients with schizophrenia or schizoaffective disorder who had received at least 4 prior injections of the long-acting risperidone at a stable dose of 25 to 50 mg participated in this positron emission tomography study. Multiple-dose ketoconazole coadministration reduced the P-gp activity as shown by fexofenadine oral challenge. Importantly, we found a strong statistical trend in this sample of 4 subjects who consistently showed a decrease in striatal fluorine 18 (F)-fallypride binding (an indication of increased D2 receptor occupancy) after ketoconazole coadministration (P = 0.057), whereas the pituitary (a region that lies outside the BBB) F-fallypride binding did not change (P = 0.99). These observations warrant further research with selective drug transporter inhibitors. We suggest that in neuroimaging studies, the pituitary drug occupancy can serve as a useful new "positive control" to evaluate whether drug occupancy is preferentially increased in brain regions that fall inside the BBB after cotreatment with P-gp and BCRP inhibitors. This is a noteworthy study design consideration regarding the future clinical testing of novel adjunct interventions aimed at modulating membrane transporter function at the BBB, with the goal of augmenting drug access into the brain compartment, particularly in treatment-resistant psychiatric illness.
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Abstract
Grapefruit juice and grapefruit product consumption have potential health benefits; however, their intake is also associated with interactions with certain drugs, including calcium channel blockers, immunosuppressants and antihistamines. The primary mechanism through which interactions are mediated is mechanism-based intestinal cytochrome P450 3A4 inhibition by furanocoumarins resulting in increased bioavailability of administered medications that are substrates. Grapefruit products have also been associated with interactions with P-glycoprotein (P-gp) and uptake transporters (e.g. organic anion-transporting polypeptides [OATPs]). Polyphenolic compounds such as flavonoids have been proposed as the causative agents of the P-gp and OATP interactions. The mechanisms and magnitudes of the interactions can be influenced by the concentrations of furanocoumarins and flavonoids in the grapefruit product, the volume of juice consumed, and the inherent variability of specific enzymes and transporter components in humans. It is therefore challenging to predict the extent of grapefruit product-drug interactions and to compare available in vitro and in vivo data. The clinical significance of such interactions also depends on the disposition and toxicity profile of the drug being administered. The aim of this review is to outline the mechanisms of grapefruit-drug interactions and present a comprehensive summary of those agents affected and whether they are likely to be of clinical relevance.
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Affiliation(s)
- Kay Seden
- NIHR Biomedical Research Centre, Royal Liverpool and Broadgreen University Hospital Trust, Liverpool, UK.
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Abstract
Tardive dyskinesia (TD) is one of the most serious adverse side effects of antipsychotic drugs and is an important topic of pharmacogenetic studies. Since there is a genetic susceptibility for developing this adverse reaction, and given that it is hard to predict its development prior to or during the early period of medication, the genetic study of TD is a promising research topic that has a direct clinical application. Moreover, such studies would improve our understanding of the genetic mechanism(s) underlying abnormal dyskinetic movement. A substantial number of case-control association studies of TD have been performed, with numbers of studies focusing on the genes involved in antipsychotic drug metabolism, such as those for cytochrome P450 (CYP) and oxidative stress related genes as well as various neurotransmitter related genes. These studies have produced relatively consistent though controversial findings for certain polymorphisms such as CYP2D6*10, DRD2 Taq1A, DRD3 Ser9Gly, HTR2A T102C, and MnSOD Ala9Val. Moreover, the application of the genome-wide association study (GWAS) to the susceptibility of TD has revealed certain associated genes that previously were never considered to be associated with TD, such as the rs7669317 on 4q24, GLI2 gene, GABA pathway genes, and HSPG2 gene. Although a substantial number of genetic studies have investigated TD, many of the positive findings have not been replicated or are inconsistent, which could be due to differences in study design, sample size, and/or subject ethnicity. We expect that more refined research will be performed in the future to resolve these issues, which will then enable the genetic prediction of TD and clinical application thereof.
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41
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Zhou SF, Wang B, Yang LP, Liu JP. Structure, function, regulation and polymorphism and the clinical significance of human cytochrome P450 1A2. Drug Metab Rev 2010; 42:268-354. [PMID: 19961320 DOI: 10.3109/03602530903286476] [Citation(s) in RCA: 179] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Human CYP1A2 is one of the major CYPs in human liver and metabolizes a number of clinical drugs (e.g., clozapine, tacrine, tizanidine, and theophylline; n > 110), a number of procarcinogens (e.g., benzo[a]pyrene and aromatic amines), and several important endogenous compounds (e.g., steroids). CYP1A2 is subject to reversible and/or irreversible inhibition by a number of drugs, natural substances, and other compounds. The CYP1A gene cluster has been mapped on to chromosome 15q24.1, with close link between CYP1A1 and 1A2 sharing a common 5'-flanking region. The human CYP1A2 gene spans almost 7.8 kb comprising seven exons and six introns and codes a 515-residue protein with a molecular mass of 58,294 Da. The recently resolved CYP1A2 structure has a relatively compact, planar active site cavity that is highly adapted for the size and shape of its substrates. The architecture of the active site of 1A2 is characterized by multiple residues on helices F and I that constitutes two parallel substrate binding platforms on either side of the cavity. A large interindividual variability in the expression and activity of CYP1A2 has been observed, which is largely caused by genetic, epigenetic and environmental factors (e.g., smoking). CYP1A2 is primarily regulated by the aromatic hydrocarbon receptor (AhR) and CYP1A2 is induced through AhR-mediated transactivation following ligand binding and nuclear translocation. Induction or inhibition of CYP1A2 may provide partial explanation for some clinical drug interactions. To date, more than 15 variant alleles and a series of subvariants of the CYP1A2 gene have been identified and some of them have been associated with altered drug clearance and response and disease susceptibility. Further studies are warranted to explore the clinical and toxicological significance of altered CYP1A2 expression and activity caused by genetic, epigenetic, and environmental factors.
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Affiliation(s)
- Shu-Feng Zhou
- Discpline of Chinese Medicine, School of Health Sciences, RMIT University, Bundoora, Victoria 3083, Australia.
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Lohoff FW, Ferraro TN. Pharmacogenetic considerations in the treatment of psychiatric disorders. Expert Opin Pharmacother 2010; 11:423-39. [DOI: 10.1517/14656560903508762] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Zhou SF, Liu JP, Chowbay B. Polymorphism of human cytochrome P450 enzymes and its clinical impact. Drug Metab Rev 2009; 41:89-295. [PMID: 19514967 DOI: 10.1080/03602530902843483] [Citation(s) in RCA: 498] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Pharmacogenetics is the study of how interindividual variations in the DNA sequence of specific genes affect drug response. This article highlights current pharmacogenetic knowledge on important human drug-metabolizing cytochrome P450s (CYPs) to understand the large interindividual variability in drug clearance and responses in clinical practice. The human CYP superfamily contains 57 functional genes and 58 pseudogenes, with members of the 1, 2, and 3 families playing an important role in the metabolism of therapeutic drugs, other xenobiotics, and some endogenous compounds. Polymorphisms in the CYP family may have had the most impact on the fate of therapeutic drugs. CYP2D6, 2C19, and 2C9 polymorphisms account for the most frequent variations in phase I metabolism of drugs, since almost 80% of drugs in use today are metabolized by these enzymes. Approximately 5-14% of Caucasians, 0-5% Africans, and 0-1% of Asians lack CYP2D6 activity, and these individuals are known as poor metabolizers. CYP2C9 is another clinically significant enzyme that demonstrates multiple genetic variants with a potentially functional impact on the efficacy and adverse effects of drugs that are mainly eliminated by this enzyme. Studies into the CYP2C9 polymorphism have highlighted the importance of the CYP2C9*2 and *3 alleles. Extensive polymorphism also occurs in other CYP genes, such as CYP1A1, 2A6, 2A13, 2C8, 3A4, and 3A5. Since several of these CYPs (e.g., CYP1A1 and 1A2) play a role in the bioactivation of many procarcinogens, polymorphisms of these enzymes may contribute to the variable susceptibility to carcinogenesis. The distribution of the common variant alleles of CYP genes varies among different ethnic populations. Pharmacogenetics has the potential to achieve optimal quality use of medicines, and to improve the efficacy and safety of both prospective and currently available drugs. Further studies are warranted to explore the gene-dose, gene-concentration, and gene-response relationships for these important drug-metabolizing CYPs.
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Affiliation(s)
- Shu-Feng Zhou
- School of Health Sciences, RMIT University, Bundoora, Victoria, Australia.
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Zhou SF, Yang LP, Zhou ZW, Liu YH, Chan E. Insights into the substrate specificity, inhibitors, regulation, and polymorphisms and the clinical impact of human cytochrome P450 1A2. AAPS JOURNAL 2009; 11:481-94. [PMID: 19590965 DOI: 10.1208/s12248-009-9127-y] [Citation(s) in RCA: 159] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Accepted: 06/16/2009] [Indexed: 11/30/2022]
Abstract
Human CYP1A2 is one of the major CYPs in human liver and metabolizes a variety of clinically important drugs (e.g., clozapine, tacrine, tizanidine, and theophylline), a number of procarcinogens (e.g. benzo[a]pyrene and aflatoxin B(1)), and several important endogenous compounds (e.g. steroids and arachidonic acids). Like many of other CYPs, CYP1A2 is subject to induction and inhibition by a number of compounds, which may provide an explanation for some drug interactions observed in clinical practice. A large interindividual variability in the expression and activity of CYP1A2 and elimination of drugs that are mainly metabolized by CYP1A2 has been observed, which is largely caused by genetic (e.g., SNPs) and epigenetic (e.g., DNA methylation) and environmental factors (e.g., smoking and comedication). CYP1A2 is primarily regulated by the aromatic hydrocarbon receptor (AhR) and CYP1A2 is induced through AhR-mediated transactivation following ligand binding and nuclear translocation. To date, more than 15 variant alleles and a series of subvariants of the CYP1A2 gene have been identified and some of they have been associated with altered drug clearance and response to drug therapy. For example, lack of response to clozapine therapy due to low plasma drug levels has been reported in smokers harboring the -163A/A genotype; there is an association between CYP1A2*1F (-163C>A) allele and the risk for leflunomide-induced host toxicity. The *1F allele is associated with increased enzyme inducibility whereas *1C causes reduced inducibility. Further studies are warranted to explore the clinical and toxicological significance of altered CYP1A2 expression and activity caused by genetic, epigenetic, and environmental factors.
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Affiliation(s)
- Shu-Feng Zhou
- Discipline of Chinese Medicine, School of Health Sciences, WHO Collaborating Center for Traditional Medicine, RMIT University, Bundoora, Victoria, Australia.
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45
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Gunes A, Ozbey G, Vural EH, Uluoglu C, Scordo MG, Zengil H, Dahl ML. Influence of genetic polymorphisms, smoking, gender and age on CYP1A2 activity in a Turkish population. Pharmacogenomics 2009; 10:769-78. [DOI: 10.2217/pgs.09.22] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aims: To study the variation in CYP1A2 activity in relation to smoking, gender, age and CYP1A2 polymorphisms. Materials & methods: CYP1A2 activity was determined by plasma paraxanthine:caffeine ratio (17X:137X) 4 h after the intake of a standardized cup of coffee in 146 Turkish healthy volunteers. Seven CYP1A2 polymorphisms (-3860G>A, -3113G>A, -2467del/T, -739T>G, -729C>T, -163C>A and 5347T>C) were analyzed. Results: The 17X:137X ratios were increased in smokers (p < 0.0001) and tended to be higher in men both among nonsmokers (p = 0.051) and smokers (p = 0.064). Age-related differences were observed only among nonsmoking women (p = 0.024). The -163C>A polymorphism correlated with 17X:137X ratios only in smokers (p = 0.006). Furthermore, increased 17X:137X ratios were observed in CYP1A2 haplotype H4 (-3860G, -3113G, -2467del, -739T, -729C, -163A and 5347T) carriers in the overall study population (p = 0.026). Multiple regression analyses including smoking, gender, -163C>A genotype and age revealed a significant influence of smoking (p < 0.0001) and gender (p = 0.002) in the overall study population. However, in nonsmokers only the influence of gender remained significant (p = 0.021), while in smokers the influence of the -163C>A genotype held the statistical significance (p = 0.019). The influence of haplotype H4 remained significant (p = 0.028) in the overall study population in similar analyses. Conclusion: Smoking has the strongest impact on CYP1A2 activity, while gender and haplotype H4 showed marginal effects. The influence of the -163C>A polymorphism on CYP1A2 activity in smokers suggests an effect on the inducibility of the enzyme.
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Affiliation(s)
- Arzu Gunes
- Department of Medical Sciences, Clinical Pharmacology, Uppsala University, SE-75185 Uppsala, Sweden
- Department of Medical Pharmacology, Faculty of Medicine, Gazi University, Ankara, Turkey
| | - Gul Ozbey
- Department of Medical Pharmacology, Faculty of Medicine, Gazi University, Ankara, Turkey
| | - Elif Hilal Vural
- Department of Medical Pharmacology, Faculty of Medicine, Gazi University, Ankara, Turkey
| | - Canan Uluoglu
- Department of Medical Pharmacology, Faculty of Medicine, Gazi University, Ankara, Turkey
| | - Maria Gabriella Scordo
- Department of Medical Sciences, Clinical Pharmacology, Uppsala University, SE-75185 Uppsala, Sweden
| | - Hakan Zengil
- Department of Medical Pharmacology, Faculty of Medicine, Gazi University, Ankara, Turkey
| | - Marja-Liisa Dahl
- Department of Medical Sciences, Clinical Pharmacology, Uppsala University, SE-75185 Uppsala, Sweden
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Abstract
There are high expectations about the capabilities of pharmacogenetics to tailor psychotropic treatment and "personalize" treatment. While a large number of associations, with generally small effect size, have been discovered, a "test" with widespread use and adoption is still missing. A more realistic picture, recognizing the important contribution of clinical and environmental factors toward overall clinical outcome has emerged. In this emerging view, genetic findings, if considered individually, may have limited clinical applications. Thus, in recent years, combinations of information in several genes have been used for the selection of appropriate therapeutic doses and for the prediction of agranulocytosis, hyperlipidemia, and response to antipsychotic and antidepressant medications. While these tests based on multiple genes show greater predictive ability than individual allele tests, their net impact on clinical consequence and costs is limited, thus leading to limited penetration into widespread clinical use. As one looks at other branches of medicine, there are successful examples of pharmacogenetic tests guiding treatment, and thus, it is reasonable to hope that with the incorporation of clinical and environmental information and the identification of new genes drawn from genome-wide analysis, will improve the predictive utility of these tests leading to their increased use by clinicians.
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Affiliation(s)
- Maria J. Arranz
- Section of Schizophrenia, Imaging and Therapeutics, Division of Psychological Medicine and Psychiatry, Institute of Psychiatry, King’s College, PO51, London SE5 8AF, UK,To whom correspondence should be addressed; tel. 44-0-207-848 0343, e-mail:
| | - Shitij Kapur
- Section of Schizophrenia, Imaging and Therapeutics, Division of Psychological Medicine and Psychiatry, Institute of Psychiatry, King’s College, PO51, London SE5 8AF, UK
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Gunes A, Dahl ML. Variation in CYP1A2 activity and its clinical implications: influence of environmental factors and genetic polymorphisms. Pharmacogenomics 2008; 9:625-37. [PMID: 18466106 DOI: 10.2217/14622416.9.5.625] [Citation(s) in RCA: 180] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
CYP1A2 is involved in the metabolism of several widely used drugs and endogenous compounds, and in the activation of procarcinogens. Both genetic and environmental factors influence the activity of this enzyme. The current knowledge regarding factors influencing the activity of CYP1A2 is summarized in this review. Substrates, inhibitors and inducers of CYP1A2 activity, as well as phenotyping probes, are discussed. The functional significance and clinical importance of CYP1A2 gene polymorphisms are reviewed and interethnic differences in the distribution of CYP1A2 variant alleles and haplotypes are summarized. Finally, future perspectives for the possible clinical applications of CYP1A2 genotyping are discussed.
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Affiliation(s)
- Arzu Gunes
- Uppsala University, Department of Medical Sciences, Clinical Pharmacology, SE-75185 Uppsala, Sweden.
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Zhang WV, D'Esposito F, Edwards RJ, Ramzan I, Murray M. Interindividual variation in relative CYP1A2/3A4 phenotype influences susceptibility of clozapine oxidation to cytochrome P450-specific inhibition in human hepatic microsomes. Drug Metab Dispos 2008; 36:2547-55. [PMID: 18809730 DOI: 10.1124/dmd.108.023671] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The atypical antipsychotic drug clozapine (CLZ) is effective in a substantial number of patients who exhibit treatment-resistance to conventional agents. CYP1A2 is generally considered to be the major enzyme involved in the biotransformation of CLZ to its N-demethylated (norCLZ) and N-oxygenated (CLZ N-oxide) metabolites in liver, but several studies have also implicated CYP3A4. The present study assessed the interplay between these cytochrome P450s (P450s) in CLZ biotransformation in a panel of hepatic microsomal fractions from 14 individuals. The relative activity of P450s 1A2 and 3A4 in microsomes was found to be a major determinant of the relative susceptibility of norCLZ formation to inhibition by the P450-selective inhibitors fluvoxamine and ketoconazole. In contrast, the activity of CYP3A4 alone was correlated with the susceptibility of CLZ N-oxide formation to inhibition by these agents. These findings suggest that both P450s may be dominant CLZ oxidases in patients and that the relative activities of these enzymes may determine clearance pathways. In vivo assessment of CYP1A2 and CYP3A4 activities, perhaps by phenotyping approaches, could assist the optimization of CLZ dosage and minimize pharmacokinetic interactions with coadministered drugs.
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Affiliation(s)
- Wei V Zhang
- Pharmacogenomics and Drug Development Group, University of Sydney, NSW 2006, Australia
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49
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Williams JA, Andersson T, Andersson TB, Blanchard R, Behm MO, Cohen N, Edeki T, Franc M, Hillgren KM, Johnson KJ, Katz DA, Milton MN, Murray BP, Polli JW, Ricci D, Shipley LA, Vangala S, Wrighton SA. PhRMA white paper on ADME pharmacogenomics. J Clin Pharmacol 2008; 48:849-89. [PMID: 18524998 DOI: 10.1177/0091270008319329] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Pharmacogenomic (PGx) research on the absorption, distribution, metabolism, and excretion (ADME) properties of drugs has begun to have impact for both drug development and utilization. To provide a cross-industry perspective on the utility of ADME PGx, the Pharmaceutical Research and Manufacturers of America (PhRMA) conducted a survey of major pharmaceutical companies on their PGx practices and applications during 2003-2005. This white paper summarizes and interprets the results of the survey, highlights the contributions and applications of PGx by industrial scientists as reflected by original research publications, and discusses changes in drug labels that improve drug utilization by inclusion of PGx information. In addition, the paper includes a brief review on the clinically relevant genetic variants of drug-metabolizing enzymes and transporters most relevant to the pharmaceutical industry.
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Affiliation(s)
- J Andrew Williams
- Pfizer Global Research and Development, 10646 Science Center Drive (CB10), San Diego, CA 92121, USA.
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Inefficacité de la clozapine en rapport avec un métabolisme augmenté et intérêt de la fluvoxamine : à propos de quatre cas. Encephale 2007; 33:811-8. [DOI: 10.1016/j.encep.2007.01.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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