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Mifsud Buhagiar L, Casha M, Grech A, Serracino Inglott A, LaFerla G. The interplay between pharmacogenetics, concomitant drugs and blood levels of amitriptyline and its main metabolites. Per Med 2022; 19:113-123. [PMID: 35118877 DOI: 10.2217/pme-2021-0022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Background: The research considers the impact of genotype-inferred variability on blood levels of amitriptyline and its main metabolites, as may be moderated by phenocopying. Patients & methods: CYP2D6 and CYP2C19 genotypes, and serum concentrations of amitriptyline, nortriptyline and hydroxymetabolites, were determined in 33 outpatients. Co-medications were reviewed to identify CYP inhibition risk. Results: CYP2C19 metabolizer status explained interpatient variation in nortriptyline to amitriptyline concentration ratios. The hydroxymetabolite to parent ratios increased with higher CYP2D6 activity scores and lower CYP2D6 inhibition risk. In patients at high CYP2D6 inhibition risk, the amitriptyline + nortriptyline concentration was, on average, 52% above the higher end of expected ranges. Conclusion: Practical construal of pharmacogenetics and drug interactions tantamount to aberrant metabolism can facilitate patient-tailored use of the established drug.
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Affiliation(s)
- Luana Mifsud Buhagiar
- Department of Pharmacy, Faculty of Medicine & Surgery, University of Malta, Msida, MSD 2080, Malta.,Medicines Authority, Malta Life Sciences Park, San Ġwann, SĠN 3000, Malta
| | - Marilyn Casha
- Department of Surgery, Faculty of Medicine & Surgery, University of Malta, Msida, MSD 2080, Malta
| | - Anton Grech
- Department of Psychiatry, Faculty of Medicine & Surgery, University of Malta, Msida, MSD 2080, Malta
| | - Anthony Serracino Inglott
- Department of Pharmacy, Faculty of Medicine & Surgery, University of Malta, Msida, MSD 2080, Malta.,Medicines Authority, Malta Life Sciences Park, San Ġwann, SĠN 3000, Malta
| | - Godfrey LaFerla
- Department of Surgery, Faculty of Medicine & Surgery, University of Malta, Msida, MSD 2080, Malta
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Darakjian L, Deodhar M, Turgeon J, Michaud V. Chronic Inflammatory Status Observed in Patients with Type 2 Diabetes Induces Modulation of Cytochrome P450 Expression and Activity. Int J Mol Sci 2021; 22:ijms22094967. [PMID: 34067027 PMCID: PMC8124164 DOI: 10.3390/ijms22094967] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 04/30/2021] [Accepted: 05/05/2021] [Indexed: 02/07/2023] Open
Abstract
Diabetes mellitus is a metabolic disease that causes a hyperglycemic status which leads, over time, to serious damage to the heart, blood vessels, eyes, kidneys and nerves. The most frequent form of diabetes is type 2 diabetes mellitus (T2DM) which is often part of a metabolic syndrome (hyperglycaemia, hypertension, hypercholesterolemia, abdominal obesity) that usually requires the use of several medications from different drug classes to bring each of these conditions under control. T2DM is associated with an increase in inflammatory markers such as interleukin-6 (IL-6) and the tumor necrosis factor alpha (TNF-α). Higher levels of IL-6 and TNF-α are associated with a downregulation of several drug metabolizing enzymes, especially the cytochrome P450 (P450) isoforms CYP3As and CYP2C19. A decrease in these P450 isoenzymes may lead to unexpected rise in plasma levels of substrates of these enzymes. It could also give rise to a mismatch between the genotypes determined for these enzymes, the predicted phenotypes based on these genotypes and the phenotypes observed clinically. This phenomenon is described as phenoconversion. Phenoconversion typically results from either a disease (such as T2DM) or concomitant administration of medications inducing or inhibiting (including competitive or non-competitive inhibition) a P450 isoenzyme used by other substrates for their elimination. Phenoconversion could have a significant impact on drug effects and genotypic-focused clinical outcomes. As the aging population is exposed to polypharmacy along with inflammatory comorbidities, consideration of phenoconversion related to drug metabolizing enzymes is of importance when applying pharmacogenomic results and establishing personalized and more precise drug regimens.
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Affiliation(s)
- Lucy Darakjian
- Tabula Rasa HealthCare, Precision Pharmacotherapy Research and Development Institute, Orlando, FL 32827, USA; (L.D.); (M.D.); (J.T.)
| | - Malavika Deodhar
- Tabula Rasa HealthCare, Precision Pharmacotherapy Research and Development Institute, Orlando, FL 32827, USA; (L.D.); (M.D.); (J.T.)
| | - Jacques Turgeon
- Tabula Rasa HealthCare, Precision Pharmacotherapy Research and Development Institute, Orlando, FL 32827, USA; (L.D.); (M.D.); (J.T.)
- Faculty of Pharmacy, Université de Montréal, Montreal, QC H3C 3J7, Canada
| | - Veronique Michaud
- Tabula Rasa HealthCare, Precision Pharmacotherapy Research and Development Institute, Orlando, FL 32827, USA; (L.D.); (M.D.); (J.T.)
- Faculty of Pharmacy, Université de Montréal, Montreal, QC H3C 3J7, Canada
- Correspondence: ; Tel.: +1-407-454-9964
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Shah RR. Genotype‐guided warfarin therapy: Still of only questionable value two decades on. J Clin Pharm Ther 2020; 45:547-560. [DOI: 10.1111/jcpt.13127] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2020] [Accepted: 02/07/2020] [Indexed: 12/20/2022]
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Abstract
The events leading up to the discovery of genetically controlled polymorphic metabolism of xenobiotics and pharmaceutical chemicals are briefly summarised with the salient historical features being emphasised. Especial attention has been given to seminal works in the then emerging field.The evolving knowledge of such polymorphic metabolism and its role in the quest for personalised medicine and the individualisation of patient drug therapy are appraised. Opinion is offered as to whether or not the full potential has been exploited and if the practical application of this information may be regarded as a success or failure within the present clinical arena.
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Affiliation(s)
- Robert L Smith
- Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, UK
| | - Stephen C Mitchell
- Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, London, UK
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Abstract
Over the years, numerous studies have supported the premise that individuals possessing the "slow acetylator" phenotype are more at risk from developing drug side-effects. Most prominent amongst these reports are those concerned with hepatotoxicity and peripheral neuropathy following treatment with isoniazid, lupus-like symptoms during procainamide therapy and experiencing hypersensitivity reactions to the various sulphonamide derivatives. Similarly, "slow acetylators" undergoing heavy exposure to arylamines and related carcinogens are more likely to develop bladder cancer. Contrariwise, there appears a slight risk of "rapid acetylators" developing pancreatic tumours.Other therapeutic agents for which polymorphic N-acetylation plays a minor role in their metabolism have been investigated but any impact of this metabolic difference on clinical efficacy or associated toxicity is still under question. In the search for clues as to the underlying aetiology, patient groups with many disease states have been examined for association with differences in N-acetylation and the majority have provided data that could be interpreted as equivocal. Studies have given contradictory, often opposing, results, calculated risk factors that are (perhaps) just significant but certainly not high, and patients within the cohorts who are always exceptions. Undoubtedly, other as yet unappreciated factors are at play.
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Affiliation(s)
- Stephen C Mitchell
- Section of Computational and Systems Medicine, Faculty of Medicine, Imperial College London, London, UK
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Suzuki Y, Muraya N, Fujioka T, Sato F, Tanaka R, Matsumoto K, Sato Y, Ohno K, Mimata H, Kishino S, Itoh H. Factors involved in phenoconversion of CYP3A using 4β-hydroxycholesterol in stable kidney transplant recipients. Pharmacol Rep 2018; 71:276-281. [PMID: 30826567 DOI: 10.1016/j.pharep.2018.12.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 11/19/2018] [Accepted: 12/14/2018] [Indexed: 10/27/2022]
Abstract
BACKGROUND Phenoconversion is a phenomenon whereby some genotypic extensive metabolizers transiently exhibit drug metabolizing enzyme activity at similar level as that of poor metabolizers. Renal failure is known to decrease CYP3A activity in humans. Indoxyl sulfate, parathyroid hormone (PTH), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) have been reported to cause CYP3A downregulation in renal failure. We measured plasma concentrations of the above compounds in stable kidney transplant recipients, and evaluated their relations with phenoconversion of CYP3A evaluated by plasma concentration of 4β-hydroxycholesterol, a biomarker of CYP3A activity. Phenoconversion was defined as a genotypic extensive/intermediate metabolizer exhibiting CYP3A activity below the cutoff value that discriminates extensive/intermediate from poor metabolizers. METHODS Sixty-three Japanese kidney transplant recipients who underwent transplantation more than 180 days prior to the study were included. Morning blood samples were collected, and CYP3A5 polymorphism as well as plasma concentrations of 4β-hydroxycholesterol, indoxyl sulfate, intact-PTH, IL-6 and TNF-α were determined. RESULTS Significantly higher plasma 4β-hydroxycholesterol concentration was observed in recipients with CYP3A5*1 allele (n = 23) compared to those without the allele (n = 40), and the cut-off value was 40.0 ng/mL. Ten recipients with CYP3A5*1 allele exhibited CYP3A activity below 40.0 ng/mL (phenoconversion). Only plasma indoxyl sulfate concentration was significantly higher in recipients with CYP3A phenoconversion compared to those without phenoconversion. CONCLUSIONS These findings suggest that higher plasma indoxyl sulfate concentration may be involved in CYP3A phenoconversion. Dose adjustment of drugs metabolized by CYP3A may be needed in patients with CYP3A5*1 allele and high blood indoxyl sulfate.
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Affiliation(s)
- Yosuke Suzuki
- Department of Clinical Pharmacy, Oita University Hospital, 1-1 Hasama-machi, Oita, 879-5593, Japan; Department of Medication Use Analysis and Clinical Research, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo, 204-8588, Japan.
| | - Nanako Muraya
- Department of Clinical Pharmacy, Oita University Hospital, 1-1 Hasama-machi, Oita, 879-5593, Japan
| | - Takashi Fujioka
- Department of Clinical Pharmacy, Oita University Hospital, 1-1 Hasama-machi, Oita, 879-5593, Japan
| | - Fuminori Sato
- Department of Urology, Oita University Faculty of Medicine, 1-1 Hasama-machi, Oita, 879-5593, Japan
| | - Ryota Tanaka
- Department of Clinical Pharmacy, Oita University Hospital, 1-1 Hasama-machi, Oita, 879-5593, Japan
| | - Kunihiro Matsumoto
- Department of Medication Use Analysis and Clinical Research, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo, 204-8588, Japan
| | - Yuhki Sato
- Department of Clinical Pharmacy, Oita University Hospital, 1-1 Hasama-machi, Oita, 879-5593, Japan
| | - Keiko Ohno
- Department of Medication Use Analysis and Clinical Research, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo, 204-8588, Japan
| | - Hiromitsu Mimata
- Department of Urology, Oita University Faculty of Medicine, 1-1 Hasama-machi, Oita, 879-5593, Japan
| | - Satoshi Kishino
- Department of Medication Use Analysis and Clinical Research, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo, 204-8588, Japan
| | - Hiroki Itoh
- Department of Clinical Pharmacy, Oita University Hospital, 1-1 Hasama-machi, Oita, 879-5593, Japan
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An analysis of allele, genotype and phenotype frequencies, actionable pharmacogenomic (PGx) variants and phenoconversion in 5408 Australian patients genotyped for CYP2D6, CYP2C19, CYP2C9 and VKORC1 genes. J Neural Transm (Vienna) 2018; 126:5-18. [DOI: 10.1007/s00702-018-1922-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 08/27/2018] [Indexed: 12/22/2022]
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Modak AS. Point-of-care companion diagnostic tests for personalizing psychiatric medications: fulfilling an unmet clinical need. J Breath Res 2017; 12:017101. [PMID: 28920579 DOI: 10.1088/1752-7163/aa8d2e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Over the last decade stable isotope-labeled substrates have been used as probes for rapid, point-of-care, non-invasive and user-friendly phenotype breath tests to evaluate activity of drug metabolizing enzymes. These diagnostic breath tests can potentially be used as companion diagnostics by physicians to personalize medications, especially psychiatric drugs with narrow therapeutic windows, to monitor the progress of disease severity, medication efficacy and to study in vivo the pharmacokinetics of xenobiotics. Several genotype tests have been approved by the FDA over the last 15 years for both cytochrome P450 2D6 and 2C19 enzymes, however they have not been cleared for use in personalizing medications since they fall woefully short in identifying all non-responders to drugs, especially for the CYP450 enzymes. CYP2D6 and CYP2C19 are among the most extensively studied drug metabolizing enzymes, involved in the metabolism of approximately 30% of FDA-approved drugs in clinical use, associated with large individual differences in medication efficacy or tolerability essentially due to phenoconversion. The development and commercialization via FDA approval of the non-invasive, rapid (<60 min), in vivo, phenotype diagnostic breath tests to evaluate polymorphic CYP2D6 and CYP2C19 enzyme activity by measuring exhaled 13CO2 as a biomarker in breath will effectively resolve the currently unmet clinical need for individualized psychiatric drug therapy. Clinicians could personalize treatment options for patients based on the CYP2D6 and CYP2C19 phenotype by selecting the optimal medication at the right initial and subsequent maintenance dose for the desired clinical outcome (i.e. greatest efficacy and minimal side effects).
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Affiliation(s)
- Anil S Modak
- Cambridge Isotope Laboratories, Inc., 3 Highwood Drive, Tewksbury, MA 01876, United States of America
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Shah RR, Shah DR. Personalized medicine: is it a pharmacogenetic mirage? Br J Clin Pharmacol 2013; 74:698-721. [PMID: 22591598 DOI: 10.1111/j.1365-2125.2012.04328.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The notion of personalized medicine has developed from the application of the discipline of pharmacogenetics to clinical medicine. Although the clinical relevance of genetically-determined inter-individual differences in pharmacokinetics is poorly understood, and the genotype-phenotype association data on clinical outcomes often inconsistent, officially approved drug labels frequently include pharmacogenetic information concerning the safety and/or efficacy of a number of drugs and refer to the availability of the pharmacogenetic test concerned. Regulatory authorities differ in their approach to these issues. Evidence emerging subsequently has generally revealed the pharmacogenetic information included in the label to be premature. Revised drugs labels, together with a flurry of other collateral activities, have raised public expectations of personalized medicine, promoted as 'the right drug at the right dose the first time.' These expectations place the prescribing physician in a dilemma and at risk of litigation, especially when evidence-based information on genotype-related dosing schedules is to all intent and purposes non-existent and guidelines, intended to improve the clinical utility of available pharmacogenetic information or tests, distance themselves from any responsibility. Lack of efficacy or an adverse drug reaction is frequently related to non-genetic factors. Phenoconversion, arising from drug interactions, poses another often neglected challenge to any potential success of personalized medicine by mimicking genetically-determined enzyme deficiency. A more realistic promotion of personalized medicine should acknowledge current limitations and emphasize that pharmacogenetic testing can only improve the likelihood of diminishing a specific toxic effect or increasing the likelihood of a beneficial effect and that application of pharmacogenetics to clinical medicine cannot adequately predict drug response in individual patients.
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