目的：建立同时测定体外肝微粒体中氟西汀及其代谓十产物去甲氟西汀的反相高效液相色谱紫外检测法。方法：含微粒体蛋白和NADPH发生系统及氟西汀的孵育液加入冰乙腈酸终止反应后，再加入去甲替林作为内标并以，z.正己烷和乙腈的混合液进行萃取，然后以反相ODS柱分离，在226nlTl处以紫外检测器进行检测。结果：孵育体系中没有明显的干扰峰出现，氟西汀和去甲氟西汀洗脱快，分离好，线性范围均为10-800ug/L，最低检测限均为5ug/L，相对回收率为94%-104%，变异系数少于9.1%。结论：本法快速，灵敏，回收率高，且萃取过程简单，可用于体外氟西汀的代谢研究。

Aims To investigate the distribution of CYP3A activity in the Chinese population, and to test for gender-related differences in CYP3A activity. Methods Using midazolam as a probe drug, CYP3A activity in 202 Chinese healthy subjects (104 men) was measured by plasma 1-hydroxymidazolam: midazolam (1-OH-MDZ: MDZ) ratio at 1 h after oral administration of 7.5mg midazolam. The different phases of the menstrual cycle including preovulatory, ovulatory and luteal phases of 66 women phenotyped with midazolam were recorded. The concentrations of 1-OH-MDZ and MDZ in plasma were measured by HPLC Results A 13-fold variation of CYP3A activity (log1-OH-MDZ: MDZ: range-0.949-0.203) was shown. The CYP3A activity was normally distributed as indicated by the frequency distribution histogram, the probit plot and the Kolmogorov-Smirnov test (P>0.05). The CYP3A activity of women was higher than that of men (median: -0.36vs-0.43, P<0.05; 95% CI for difference: -0.127,-0.012). There was a significant difference in CYP3A activity between the three phases of the menstrual cycle. The activity was highest in the preovulatory phase and decreased sequentially in the ovulatory and luteal phases (P<0.05). Conclusions A normal distribution of CYP3A activity was observed in the Chinese population. The CYP3A activity is higher in female subjects than in males. CYP3A activity differed across the phases of the menstrual cycle.

An gas chromatography-electron-capture detection method has been developed for simultaneous determination of fluoxetine and p-trifluoromethylphenol (TFMP), an O-dealkylated metabolite of fluoxetine in human liver microsomes. Prior to the analysis, aliquots of alkalinized microsomal mixture were extracted with ethyl acetate solvent containing acetonitrile (10%, v/v) and the derivatizing reagent, pentafluorobenzenesulfonyl chloride (0.1%, v/v). The organ phase was retained and taken to dryness, the residue was reconstituted in methanol, and the aliquot of extracts was injected directly into a gas chromatograph equipped with an electron-capture detector. 2, 4 Dichlorophenol was added to the initial incubation mixture and carried through the procedure as the internal standard. The method provided the mean recoveries of up to 103% for fluoxetine and 104% for TFMP. Acceptable relative standard deviations were found for both within-run and day-to-day assays. The practical limit of detection (signal-to-noise ratio53) was 1.62ng/ml for TFMP and 6.92ng/ml for fluoxetine in human liver microsomes, and the limit of quantitation was 8.1 pg for TFMP and 34.6 pg for fluoxetine. The assay is rapid and sensitive and has been applied successfully to simultaneous quantification of fluoxetine and TFMP in human liver microsomes with different CYP2C19 genotypes.

Objective: 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. Methods: A single oral 100-mg dose of sertraline was administered to 6 subjects who were extensive metabolizers and 6 subjects who were poor metabolizers recruited from 77 healthy Chinese volunteers whose genotypes were predetermined by polymerase chain reaction-based amplification, followed by restriction fragment length polymorphism analysis. Phenotypes were determined by use of the omeprazole metabolic rate. The plasma concentrations of sertraline and desmethylsertraline were determined by gas chromatography with electron-capture detection. Results: Six poor metabolizers with m1 mutation had area under the plasma concentration versus time curve (AUC0-∞) values (983.6±199.3μg·h/L versus 697.6±133.0μg·h/L; P<.05) and terminal elimination half-life values of sertraline (35.5±5.6 hours versus 23.5±4.4 hours; P<.01) that were significantly higher than the values in 6 extensive metabolizers who were either homozygous or heterozygous for CYP2C19*1. The oral clearance of sertraline in poor metabolizers (105.3±19.4L/h) was significantly lower than that of extensive metabolizers (148.4±28.6L/h). The area under the concentration-time curve from 0 to 144 hours and the maximum plasma concentration of desmethylsertraline in poor metabolizers were significantly lower than the values of extensive metabolizers (627.6±203.8μg·h/L versus 972.1±270.3μg·h/L; P<.05; and 23.6±6.5nmol/L versus 32.4±8.2nmol/L; P<.01; respectively).

The study was designed to define the contribution of cytochrome P450 2C19 (CYP2C19) and cytochrome P450 3A4 (CYP3A4) to citalopram N-demethylation and to evaluate the relationship between the disposition of citalopram and CYP2C19 genotype. A single oral 40mg dose of citalopram was administered to eight extensive metabolizers and five poor metabolizers recruited from 77 healthy Chinese volunteers whose genotypes and phenotypes were predetermined. The plasma concentrations of citalopram and desmethylcitalopram were N determined by high-performance liquid chromatography. It was found that the genotype of CYP2C19 had a significant effect on the N-demethylation of citalopram. Poor metabolizers with m1 mutation had higher area under the plasma concentration versus time curve (AUC03) values than did extensive metabolizers. Terminal eliminationelimination half-life (t1/2) values of citalopram in poor metabolizers were significantly higher than the values in extensive metabolizers who were either homozygous or heterozygous with CYP2C19*1. The oral clearance (CLoral) of citalopram in poor metabolizers was significantly lower than that of extensive metabolizers. The AUC03 and maximum plasma concentration (Cmax) of desmethylcitalopram in poor metabolizers were significantly lower than the values of extensive metabolizers. The results show that CYP3A4 is not the major enzyme in the N-demethylation of citalopram among extensive metabolizers. The polymorphism of CYP2C19 plays an important role in the Ndemethylation of citalopram in vivo. The extensive metabolizers and poor metabolizers of CYP2C19 had significant difference in disposition of citalopram in vivo.