Analysis of human interindividual and racial differeness of drug response and metabolism : Approach by the method of diagnosis by gene analysis

7名日本健康志愿者服用美芬妥英，这些人是美芬妥英4 '-羟基化的表型广泛（EM）和弱代谢型（PM）。通过测量R-和S-美芬妥英4 '-对12份日本人肝微粒体样本和5份高加索人样本进行EM和PM表型分型。9名日本人和5名高加索人被判定为EM，3名日本人为PM。从9名EM和4名PM中分离基因组DNA，和DNA序列进行了分析，推定的美芬妥英4 '-羟化酶序列比较EM和PM的CYP 2C 9/CYP 2C 10基因序列，结果表明，在PM中，CYP 2C 19基因的第4外显子序列发生了核苷酸替换，在PM中，CYP 2C 19基因的第5外显子前的第4内含子序列发生了核苷酸替换，在PM中，CYP 2C 19基因的第5外显子前的第4内含子序列发生了核苷酸替换，在两种情况下，CYP 2C 19基因在PM肝脏中均不表达，在PM肝脏中，CYP 2C 19基因的第5外显子前的第4内含子序列发生了核苷酸替换，在PM肝脏中，CYP 2C 19基因的第4内含子序列发生了核苷酸替换。用EM和PM肝微粒体研究了地西泮的体外代谢。在高底物浓度下，地西泮N-去甲基化速率约为3-羟基化速率的1/3（0.2mM）时，N-去甲基化速率随底物浓度的降低而增加地西泮N-去甲基化似乎是由CYP 2C形式介导的。另一方面，地西泮3-羟基化被CYP 3A型选择性催化，这些结果与体内地西泮N-去甲基化和S-去甲基化的观察一致。美芬妥英4 '-羟基化在人体中密切相关。

Mephenytoin was administered to seven healthy volunteers of Japanese, and those were phenotyped extensive(EM)and poor metabolizers(PM)of mephenytoin 4'-hydroxylation.Six subjects were judged as EM,and one as PM.Twelve liver microsomal samples of Japanese and five samples of Caucasian were also phenotyped EM and PM by measuring R-and S-mephenytoin 4'-hydroxylation.Nine Japanese and five Caucasian subjects were judged as EM and three Japanese were PM.Genomic DNAs were isolated from nine EM and four PM,and DNA sequences were analyzed and the sequences of putative mephenytoin 4'-hydroxylases (CYP2C forms) were compared between EM and PM.No difference was observed on the sequences of CYP2C9/18 between EM and PM.Anucleotide substitution was detected in the sequence of exon 4 of CYP2C19 in PM,phenotyped in vivo.Another mutation was detected in the sequense of intron 4 just before exon 5 of CYP2C19 in PM,phenotyped in vitro.In either case, CYP2C19 does not express in PM livers, Metabolism of diazepam was studied in vitro by using liver microsomes obtained from EM and PM.The rate of diazepam N-demethylation was about one-third that of 3-hydoxylation at a high substrate concentration(0.2mM), however, the rate of N-demethylation increases with the decrease in the substrate concentration (-0.02mM).Diazepam N-demethylation seems to be mediated by CYP2C forms.On the other hand, diazepam 3-hydroxylation was selectively catalyzed by CYP3A forms.These results were consistent with the observation in vivo that diazepam N-demethylation and S-mephenytoin 4'-hydroxylation are closely correlated in humans.