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Brosen K. Pharmacogenetics of drug oxidation via cytochrome P450 (CYP) in the populations of Denmark, Faroe Islands and Greenland. Drug Metab Pers Ther 2015; 30:147-63. [PMID: 25719307 DOI: 10.1515/dmdi-2014-0029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 12/09/2014] [Indexed: 11/15/2022]
Abstract
Denmark, the Faroe Islands and Greenland are three population-wise small countries on the northern part of the Northern Hemisphere, and studies carried out here on the genetic control over drug metabolism via cytochrome P450 have led to several important discoveries. Thus, CYP2D6 catalyzes the 2-hydroxylation, and CYP2C19 in part catalyzes the N-demethylation of imipramine. The phenomenon of phenocopy with regard to CYP2D6 was first described when Danish patients changed phenotype from extensive to poor metabolizers during treatment with quinidine. It was a Danish extensive metabolizer patient that became a poor metabolizer during paroxetine treatment, and this was due to the potent inhibition of CYP2D6 by paroxetine, which is also is metabolized by this enzyme. Fluoxetine and norfluoxetine are also potent inhibitors of CYP2D6, and fluvoxamine is a potent inhibitor of both CYP1A2 and CYP2C19. The bioactivation of proguanil to cycloguanil is impaired in CYP2C19 poor metabolizers. The O-demethylation of codeine and tramadol to their respective my-opioid active metabolites, morphine and (+)-O-desmethyltramadol was markedly impaired in CYP2D6 poor metabolizers compared to extensive metabolizers, and this impairs the hypoalgesic effect of the two drugs in the poor metabolizers. The frequency of CYP2D6 poor metabolizers is 2%-3% in Greenlanders and nearly 15% in the Faroese population. The frequency of CYP2C19 poor metabolizers in East Greenlanders is approximately 10%. A study in Danish mono and dizygotic twins showed that the non-polymorphic 3-N-demethylation of caffeine catalyzed by CYP1A2 is subject to approximately 70% genetic control.
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LLerena A, Naranjo MEG, Rodrigues-Soares F, Penas-LLedó EM, Fariñas H, Tarazona-Santos E. Interethnic variability ofCYP2D6alleles and of predicted and measured metabolic phenotypes across world populations. Expert Opin Drug Metab Toxicol 2014; 10:1569-83. [DOI: 10.1517/17425255.2014.964204] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Abstract
Response to drugs can vary between individuals and between different ethnic populations. The biological (age, gender, disease and genetics), cultural and environmental factors which contribute to these variations are considered in this review. The most important aspect is the genetic variability between individuals in their ability to metabolize drugs due to expression of 'polymorphic' enzymes. Polymorphism enables division of individuals within a given population into at least two groups, poor metabolisers (PMs) and extensive metabolisers (EMs) of certain drugs. The two most extensively studied genetic polymorphisms are those involving cytochrome P450 2D6 (CYP2D6) and CYP2C19. CYP2D6 metabolizes a number of antidepressants, antipsychotics, beta-adrenoceptor blockers, and antiarrhythmic drugs. About 7% of Caucasians and 1% of Asians are PMs of CYP2D6 substrates. CYP2C19 enzyme participates in the metabolism of omeprazole, propranolol and psychotropic drugs such as hexobarbital, diazepam, citalopram, imipramine, clomipramine and amitriptyline. The incidence of PMs of CYP2C19 substrates is much higher in Asians (15-30%) than in Caucasians (3-6%). Variations in metabolism of psychotropic drugs result in variations in their pharmacokinetic parameters. This may lead to clinically significant intra- and inter-ethnic differences in pharmacological responses. Such variations are discussed in this review. Differential receptor-mediated response may play a role in ethnic differences in responses to antipsychotics and tricyclic antidepressants, but such pharmacodynamic factors remain to be systematically investigated. The results of studies of ethnic differences in response to psychopharmacotherapy appear to be discrepant, most probably due to limitations of study design, small sample size, inadequately defined study sample, and lack of control of confounding factors. The clinical value of understanding pharmacogenetics is in its use to optimize therapeutic efficacy, to prevent toxicity of those drugs whose metabolism is catalysed by polymorphic isoenzymes, and to contribute to the rational design of new drugs. Finally, applications and impact of pharmacogenetics in the field of psychopharmacotherapy are discussed.
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Affiliation(s)
- N Poolsup
- Centre for Evidence-Based Pharmacotherapy, Aston University, Birmingham, U.K
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Jurima-Romet M, Foster BC, Casley WL, Rode A, Vloshinsky P, Huang HS, Geertsen S. CYP2D6-related oxidation polymorphism in a Canadian Inuit population. Can J Physiol Pharmacol 1997. [DOI: 10.1139/y97-013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Abstract
Genetic polymorphisms of drug metabolizing enzymes are well recognized. This review presents molecular mechanisms, ontogeny and clinical implications of genetically determined intersubject variation in some of these enzymes. Included are the polymorphic enzymes N-acetyl transferase, cytochromes P4502D6 and 2C, which have been well described in humans. Information regarding other Phase I and Phase II polymorphic pathways, such as glutathione and methyl conjugation and alcohol and acetaldehyde oxidation continues to increase and are also discussed. Genetic factors effecting enzyme activity are frequently important determinants of the disposition of drugs and their efficacy and toxicity. In addition, associations between genetic differences in these enzymes and susceptibility to carcinogens and teratogens have been reported. Ultimately, the application of knowledge regarding these genetic factors of enzyme activity may guide medical therapy and minimize xenobiotic-induced disease.
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Affiliation(s)
- D G May
- Department of Pediatrics, Wayne State University, Children's Hospital of Michigan, Detroit 48201
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Orzechowska-Juzwenko K, Pawlik J, Niewiński P, Milejski P, Dembowski J, Turek J, Goździk A, Swiebodzki L, Hora Z. Genetically determined sparteine oxidation polymorphism in a Polish population. Eur J Clin Pharmacol 1994; 46:481-3. [PMID: 7957549 DOI: 10.1007/bf00191917] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The genetic oxidation polymorphism was determined in 160 healthy Polish volunteers from the south-west of Poland (Wrocław region), using sparteine as a model drug. The results of a Polish population study revealed a bimodal distribution of the sparteine metabolic ratio and showed the existence of two oxidation phenotypes designated as extensive and poor metabolizers. The frequency of poor metabolizers in our study (8.8%) compares well with most results of poor oxidation metabolizers in Caucasian populations.
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Spina E, Campo GM, Avenoso A, Caputi AP, Zuccaro P, Pacifici R, Gatti G, Strada G, Bartoli A, Perucca E. CYP2D6-related oxidation polymorphism in Italy. Pharmacol Res 1994; 29:281-9. [PMID: 8058599 DOI: 10.1016/1043-6618(94)80051-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The distribution of the oxidation polymorphism related to cytochrome CYP2D6 (debrisoquine type) was determined in 246 healthy Italian volunteers. Phenotyping was based on HPLC determination of the dextrometorphan/dextrorphan concentration ratio (metabolic ratio) in urine samples collected over an 8 h interval following a single oral 30 mg dose of dextromethorphan hydrobromide. Urinary excretion of dextromethorphan showed a wide interindividual variability, ranging from < or = 0.04 to 3.9% and from 0.5 to 79.6% of the dose, respectively. Metabolic ratios ranged from < or = 0.001 to 6.6. Eleven of the 246 subjects showed a metabolic ratio greater than 0.30, indicating that 4.5% of the population could be ascribed to the poor metabolizer status. The frequency of the poor metabolizer phenotype in this population is within the range described for other Caucasian ethnic groups.
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Affiliation(s)
- E Spina
- Institute of Pharmacology, School of Medicine, University of Messina, Italy
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Sommers DK, Moncrieff J, Avenant JC. Absence of polymorphism of sparteine oxidation in the South African Venda. Hum Exp Toxicol 1991; 10:175-8. [PMID: 1678945 DOI: 10.1177/096032719101000304] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
1 This study has found no occurrence of poor metabolism of sparteine within a South African Venda population of 97 subjects. 2 On the basis of MR (metabolic ratio) the mean and distribution of the results are very similar to those found in Ghanaians. 3 The distribution is also similar to that for fast metabolizers in Caucasians. 4 It is concluded that different P450 cytochromes are responsible for immediate oxidation of debrisoquine and sparteine, but that both may be activated by the same P450 reductase.
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Affiliation(s)
- D K Sommers
- Department of Pharmacology, University of Pretoria, South Africa
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Abstract
Interethnic differences are important factors accounting for interindividual variations in drug responsiveness. However, these differences in drug response have been a relatively neglected area of investigation, so that similar doses are prescribed to different ethnic populations without consideration of interethnic pharmacokinetic and pharmacodynamic variation. With the increased recognition of genetically determined polymorphism in metabolising ability as an important factor in drug disposition, concern has developed for the importance of individualising drug dose to account for racial differences. The recognition of these differences in drug disposition and responses calls into question the failure of drug licensing authorities to demand information on dosage, efficacy and toxicity in different ethnic groups, and to accept data from limited ethnic groups such as Caucasians. This article reviews the evidence for ethnic differences in drug disposition and sensitivity and should encourage further investigations to elucidate the extent of such differences, their causes and their therapeutic impact.
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Affiliation(s)
- A J Wood
- Department of Pharmacology, Vanderbilt University, School of Medicine, Nashville, Tennessee
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Wanwimolruk S, Patamasucon P, Lee EJ. Evidence for the polymorphic oxidation of debrisoquine in the Thai population. Br J Clin Pharmacol 1990; 29:244-7. [PMID: 2306417 PMCID: PMC1380091 DOI: 10.1111/j.1365-2125.1990.tb03627.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Debrisoquine polymorphism has been studied extensively in Caucasian populations. The prevalence of the poor metaboliser phenotype is 3-10% in European and American Caucasian populations but appears to be very low in Asian populations. This study was carried out to determine the metabolic oxidation status in 173 Thai subjects. Phenotyping was performed using the metabolic ratio (MR) calculated as the 0-8 h urinary output of debrisoquine/0-8 h urinary output of 4-hydroxydebrisoquine after oral administration of 10 mg debrisoquine hemisulphate. Two subjects (1.2%) were phenotyped as poor metabolisers; they had MR values of 13.17 and 92.04. The incidence of the poor metaboliser phenotype of debrisoquine oxidation of 1.2% seems to be lower in the Thai population compared with that in various Caucasian populations.
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Affiliation(s)
- S Wanwimolruk
- Department of Pharmacology, Prince of Songkla University, Hand-Yai, Thailand
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Eichelbaum M, Gross AS. The genetic polymorphism of debrisoquine/sparteine metabolism--clinical aspects. Pharmacol Ther 1990; 46:377-94. [PMID: 2188269 DOI: 10.1016/0163-7258(90)90025-w] [Citation(s) in RCA: 243] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
It has been established that the metabolism of more than twenty drugs, including antiarrhythmics, beta-adrenoceptor antagonists, antidepressants, opiates and neuroleptics is catalyzed by cytochrome P-450dbl. The activity of this P-450 isozyme is under genetic rather than environmental control. This article discusses the therapeutic implications for each of the classes of drugs affected by this genetic polymorphism in drug metabolism. Not only are the problems associated with poor metabolizers who are unable to metabolize the compounds discussed, but it is also emphasized that it is difficult to attain therapeutic plasma concentrations for some drugs in high activity extensive metabolizers.
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Affiliation(s)
- M Eichelbaum
- Dr Margarete Fischer-Bosch-Institut für Klinische Pharmakologie, Stuttgart, F.R.G
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Abstract
The Inuit (Eskimo) gene pool is in many respects similar to that of East Asian populations. Some polymorphisms imply frequent occurrence of disorders comparatively rare in Western Europe (e.g. lactose and sucrose malabsorptions). Low frequencies of alleles for slow isoniazid acetylation and sparteine/debrisoquine oxidation indicate slow elimination of a multitude of drugs. Autoimmune disorders (e.g. rheumatoid arthritis, insulin-dependent diabetes mellitus, Graves' disease and psoriasis) are rare, possibly explained by the associations of these disorders with HLA-alleles rare in the Inuit (e.g. HLA-B8). A correspondingly high incidence of reactive arthritis may be explained by a frequent HLA-B27 allele. The prevalence of disorders due to instability of mesenchymal tissues (e.g. spondylolisthesis, osteoarthrosis, hernia, heart block) still requires a biochemical explanation. Attention is drawn to the urgency of genetic studies in the Arctic because of the accelerating hybridization of the Inuit in all circumpolar areas.
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Affiliation(s)
- B Harvald
- Department of Internal Medicine C, Odense University Hospital, Denmark
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Paar WD, Schuhler H, Fimmers R, Dengler HJ. Sparteine oxidation polymorphism: phenotyping by measurement of sparteine and its dehydrometabolites in plasma. Eur J Clin Pharmacol 1989; 36:555-60. [PMID: 2590312 DOI: 10.1007/bf00637735] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Phenotyping of the ability to oxidize sparteine was markedly facilitated by analyzing sparteine and dehydrosparteines in a single plasma sample by gas chromatography. The definitive identification of extensive and poor metabolizers was possible only 90 min after ingestion of 100 mg sparteine sulphate. In 121 healthy volunteers determination of the plasma level ratio was compared to the established determination of the metabolic ratio in urine. In each subject the alloted phenotype was the same by both methods. Plasma and urine analysis showed 9.9% of poor metabolizers.
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Affiliation(s)
- W D Paar
- Department of Internal Medicine, University of Bonn, Bonn-Venusberg, Federal Republic of Germany
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Horai Y, Ishizaki T, Eichelbaum M, Hashimoto K, Chiba K, Dengler HJ. Further analysis of sparteine oxidation in a Japanese population and comparison with data observed in different ethnic populations. Xenobiotica 1988; 18:1077-84. [PMID: 3227705 DOI: 10.3109/00498258809042230] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
1. Data on the oxidation polymorphism of sparteine (SP) studied in 84 unrelated Japanese subjects of whom two (2.4%) were classified as poor metabolizers (PMs) were re-evaluated. The data were obtained from 6-hour urinary excretion ratios of SP to 2- and 5-dehydrosparteines (DHS), after an oral dose of 100 mg of SP sulphate. 2. Urinary excretion of both SP and DHS correlated with the SP/DHS ratio (rs = 0.862 and -0.756, respectively, P less than 0.001). In addition, urinary excretion of 2-DHS, 5-DHS or total DHS discriminated between PMs and extensive metabolizers (EMs). There was also a highly significant correlation (rs = 0.669, P less than 0.001) between the urinary excretion of 2- and 5-DHS. 3. These re-evaluated results on the oxidation polymorphism of SP indicate that 2- and 5-DHS formation from SP shares a common metabolic pathway (presumably via the same P-450 isozyme), and that the SP/DHS ratio, conventionally used as a discriminating index between PMs and EMs, quantitatively reflects the capacity of 2- and 5-DHS formation. 4. The benefit of using a shorter (6 h) collection period for assessing the individual oxidation phenotype of SP and inter-ethnic comparison of SP oxidation is also discussed.
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Affiliation(s)
- Y Horai
- Division of Clinical Pharmacology, National Medical Center, Tokyo, Japan
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