2000 Fiscal Year Final Research Report Summary
Individual Difference in Drug Metabolism and Disposition : Toxicological Significance of Genotypes and Phenotypes of S-mephenytoin 4'-hydroxylase(CYP2C19)
| Project/Area Number |
11670416
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Legal medicine
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| Research Institution | Tottori University |
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Principal Investigator |
JUN Ikebuchi Department of Legal Medicine, Faculty of Medicine, Tottori University, Research Associate, 医学部, 助手 (30150361)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHITO Irizawa Department of Legal Medicine, Faculty of Medicine, Tottori University, Professor, 医学部, 教授 (90112226)
ISAO Yuasa Department of Legal Medicine, Faculty of Medicine, Tottori University, Assistant Professor, 医学部, 講師 (00093633)
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| Project Period (FY) |
1999 – 2000
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| Keywords | drug metabolizing enzyme / cytochrome P-450 / CYP2C19 / genotype / phenotype / genetic polymorphism / individual difference / toxicology |
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| Research Abstract |
The 4'-hydroxylation of S-mephenytoin has been shown to be mediated by CYP2C19. It is also important in the metabolism of a number of relatd hydantoins and barbiturates, as well as in that of structurally dissimilar drugs such as omeprazole, proguanil, and citalopram. As a result, large interphenotypic differences occur in the disposition of these drugs, which may affect their toxicity and efficacy.
Therefore, we examined the relationship between genetic polymorphism of CYP2C19 and metabolism of omeprazole in order to assess the severity and to predict the outcome of poisoning for the forensic and clinical toxicology. In this study, we prepared the DNA samples from the blood of unrelated healthy Japanese, and developed a rapid and simple genotyping method using a polymerase chain reaction (PCR) based restriction fragment length polymorphism. Genotyping procedures for the identification of CYP2C19 were performed by PCR amplification with use of the allele-specific primers described by de Morais et al. with minor modifications. PCR products were digested with the restriction enzymes, and were analyzed by polyacrylamide gel electrophoresis. Furthermore, CYP2C19 phenotypes were determined by measuring omeprazole and hydroxyomeprazole concentrations in the serum, collected at 2 hours after omeprazole ingestion, by high performance liquid chromatography described by Marinac et al. with minor modifications. Consequently, the genotypes observed were CYP2C19^*1A (wild type : wt), CYP2C19^*2 (m1), and CYP2C19^*3 (m2). The omeprazole hydroxylation index of wild-type was -1.15, whereas hetero-type was -0.78, and homo-mutated type 1.22. The genotype of CYP2C19 correlated with the phenotype. These results proved that genotyping assays of drug metabolizing enzymes would play more important role in assessing the severity and predicting the outcome of poisoning for forensic and clinical toxicology.
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