Nan He

Pharmacokinetics of sertraline in relation to genetic polymorphism of CYP2C19

Our objective was to evaluate the relationship between the disposition of sertraline and the presence of the CYP2C19 gene and to define the contribution of cytochrome P450 2C19 (CYP2C19) to sertraline N‐demethylation.

Effect of the gene dosage of CYP2C19 on diazepam metabolism in Chinese subjects

To determine whether the gene dosage of CYP2C19 affects the metabolism of diazepam and desmethyldiazepam in healthy Chinese subjects.

Assessment of cytochrome P450 activity by a five-drug cocktail approach

Our goal was to establish and validate a modified cocktail approach including probe drugs caffeine, chlorzoxazone, mephenytoin, metoprolol, and midazolam for simultaneous phenotyping of CYP1A2, CYP2E1, CYP2C19, CYP2D6, and CYP3A.

CYP2C19 genotype and S-mephenytoin 4'-hydroxylation phenotype in a Chinese Dai population.

Abstract.Aims: To investigate the incidence of the CYP2C19 polymorphism in the Chinese Dai population. Methods: One hundred and ninety-three healthy Chinese Dai volunteers were identified with respect to CYP2C19 by genotype and phenotype analyses. A polymerase chain reaction–restriction fragment length polymorphism method was performed for genotyping procedures. The 4′-hydroxymephenytoin (4′-OH-MP) and S/R-mephenytoin (S/R-MP) excreted in the urine were determined by high-performance liquid chromatography and gas chromatography, respectively. Results: Eighteen subjects were identified as poor metabolisers (PMs). The frequency of PMs in the Chinese Dai subjects was 9.3% (95% confidence interval 5.2, 13.4), which is lower than that in the Chinese Han population (P<0.05). Chinese Dai subjects had a higher frequency of the mutant CYP2C19*2 allele (0.303) and a lower frequency of the mutant CYP2C19*3 allele (0.034). These two mutant alleles could explain all deficiencies of CYP2C19 activity in the Chinese Dai subjects. The frequency of the CYP2C19*3 allele is significantly lower than that in the Chinese Han population (P<0.05). The mean S/R ratio was lower in the homozygous extensive metabolisers (EMs) compared with that in heterozygous EMs (P<0.01), and the latter was lower than that in the PMs (P<0.01). Furthermore, the mean S/R ratio in CYP2C19*3/CYP2C19*2 heterozygous PMs was possibly lower than that in the CYP2C19*2/CYP2C19*2 homozygous PMs (P<0.05). Conclusion: The frequencies of PMs and CYP2C19*3 allele in the Chinese Dai population are significantly lower than those in the Han population. The CYP2C19 genotype analysis is largely consistent with the mephenytoin phenotype analysis. The variability of S/R ratios in EMs and PMs shows a gene–dosage effect.

Inhibitory effect of troleandomycin on the metabolism of omeprazole is CYP2C19 genotype-dependent

1. Eighteen healthy CYP2C19 genotyped male subjects were administered a 20-mg oral dose of omeprazole (OP) alone or received troleandomycin (TAO) 500 mg daily for 2 days before the dose of OP was administered. Blood samples were obtained and OP 5-hydroxyomeprazole (5-OH-OP) and OP sulfone in plasma were determined by reversed-phase HPLC. 2. The mean C max, AUC and CL for OP in poor metabolizers (PMs) were greater with TAO than without TAO. The C max and AUC of 5-OH-OP in PMs were significantly (p < 0.05) less with TAO than without TAO. The differences in 5-OH-OP between heterozygous extensive metabolizers (EMs) with TAO versus without TAO were similar to those observed in PMs, except for the AUC. However, in homozygous EMs, there were no statistical differences for the effect of TAO. 3. The effect of TAO on the metabolism of OP and its two principal metabolites differs in different genotype groups of CYP2C19. CYP3A4 not only plays a dominant role in the formation of OP sulfone, but also it contributes to the 5-hydroxylation of OP. Both CYP2C19 and CYP3A contribute to the further elimination of 5-OH-OP and OP sulfone.

Distributive characteristics of Ser49Gly and Gly389Arg genetic polymorphisms of β 1 -adrenoceptor in Chinese Han and Dai populations

AbstractAim:Genetic polymorphisms causing Ser49Gly and Gly389Arg mutants of β1- adrenoceptor may result in significant changes in the function of this receptor. The aim of the present study was to investigate the frequencies of the Ser49Gly and Gly389Arg mutant alleles in healthy Chinese populations and to investigate the differences between 2 Chinese ethnic groups (Han and Dai populations) with respect to the frequencies of these alleles.Methods:A total of 225 Han Chinese and 175 Dai Chinese unrelated healthy volunteers were recruited for this study. Genomic DNA was extracted from peripheral blood leukocytes by using a standard manual chloroform-phenol extraction. Fragments spanning the 2 polymorphisms were amplified by using polymerase chain reaction with template genomic DNA and relevant primers. The DNA products including the polymorphic loci were subjected to restriction endonuclease digestion with Eco0109I and BcgI. Digested fragments were detected with an ultraviolet detector after electrophoresis (100 V for approximately 1.5 h).Results:The frequencies of the Gly49 and Arg389 alleles were, respectively, 16.2% and 76.4% in the Han population and 14.6% and 75.7% in the Dai population.Conclusion:The polymorphisms causing the Ser49Gly and Gly389Arg mutations of the β1-adrenoceptor existed in both healthy Han and Dai Chinese populations. The frequencies of the Ser49Gly and Gly389Arg mutant alleles were not significantly different in the Han and Dai populations. However, the frequency of the Gly389 variant seems to be significantly lower in these 2 populations than in an African-American population.