细胞色素P450 CYP2C9*3对格列本脲和氯诺昔康中国人体药代动力学的影响

目的研究人体内细胞色素P450 2C9酶突变等位基因CYP2C9*3对格列本脲和氯诺昔康药代动力学的影响。方法采用PCR-RFLP方法对83名无血源关系的受试者进行CYP2C9*3等位基因的筛查，基因型为CYP2C9*1/*3(n=7)和*1/*1(n=11)的受试者分别参加了格列本脲和氯诺昔康的人体药代动力学试验。采用LC/MS/MS法分别测定受试者口服格列本脲(2.5 mg)和氯诺昔康(8 mg)后不同时刻血浆中格列本脲和氯诺昔康的浓度。结果两组受试者口服格列本脲后，CYP2C9*1/*3组AUC_0-∞显著增加，为CYP2C9*1/*1组的1.5倍，CL/F降低了40%；两组受试者口服氯诺昔康后，CYP2C9*1/*3组AUC_0-∞亦显著增加，为CYP2C9*1/*1组的2.2倍，CL/F降低了55%。结论CYP2C9酶的突变等位基因CYP2C9*3对格列本脲和氯诺昔康的药代动力学有显著性影响。     

OATP1B1 polymorphism is a major determinant of serum bilirubin level but not associated with rifampicin-mediated bilirubin elevation

1. Elevated serum bilirubin levels are caused mainly by liver diseases, haematolysis, genetic defects and drug intake. Unconjugated bilirubin (UCB) is taken up into hepatocytes by human organic anion transporting polypeptide 1B1 (OATP1B1; encoded for by the SLCO1B1 gene). The present study was performed to determine the association between SLCO1B1 gene polymorphisms and serum bilirubin levels in vivo. Moreover, the effects of administration of low-dose rifampicin on serum bilirubin levels in different SLCO1B1 genotypes was examined. 2. Serum bilirubin levels were examined in 42 healthy volunteers who had been analysed for SLCO1B1 genotype (seven, 13, 14 and eight with SLCO1B1 genotypes *1a/*1a, *1b/*1b, *1b/*15 and *15/*15, respectively). Among them, 24 subjects (seven, seven, eight and two with SLCO1B1 genotypes *1a/*1a, *1b/*1b, *1b/*15 and *15/*15, respectively) were selected to participate in an open-label, two-phase clinical trial. Each was given 450 mg rifampicin orally once daily at 2000 hours for 5 consecutive days. Serum bilirubin concentrations at 0800 hours on the 1st and 6th days were compared between the different SLCO1B1 genotypes. 3. In the 42 volunteers, the mean (+/-SD) serum UCB in both SLCO1B1*1b/*15 and *15/*15 groups was significantly higher than that in the SLCO1B1*1b/*1b group (11.07 +/- 2.31, 13.01 +/- 3.87 and 8.21 +/- 2.68 micromol/L, respectively; P = 0.009 and P < 0.001). Total bilirum (T.BIL) in both the SLCO1B1*1b/*15 and *15/*15 groups was significantly higher than that in the SLCO1B1*1b/*1b group (16.69 +/- 4.09, 20.71 +/- 5.12 and 13.06 +/- 5.12 micromol/L, respectively; P = 0.029 and P < 0.001). The direct bilirubin (D.BIL) in the SLCO1B1*15/*15 group was significantly higher than that in the SLCO1B1*1b/*1b group (7.69 +/- 1.81 vs 4.85 +/- 1.81 micromol/L, respectively; P = 0.001). Rifampicin significantly increased UCB, T.BIL and D.BIL concentrations in 24 healthy volunteers (17.68 +/- 5.96 vs 13.95 +/- 4.44 micromol/L (P = 0.040), 5.72 +/- 2.01 vs 4.35 +/- 1.50 micromol/L (P = 0.028) and 12.00 +/- 4.26 vs 9.61 +/- 3.15 micromol/L (P = 0.035), respectively). However, the extent of the increase in serum bilirubin caused by 450 mg rifampicin for 5 days was not affected by SLCO1B1 genotype. 4. Genetic polymorphism in SLCO1B1 is a major determinant of interindividual variability in the serum bilirubin level. SLCO1B1*15 carriers had higher baseline serum UCB, T.BIL and D.BIL levels compared with subjects with the SLCO1B1*1a/*1a and SLCO1B1*1b/*1b genotypes. SLCO1B1*15/*15 homozygotes are more susceptible to hyperbilirubinaemia. Serum bilirubin levels could be increased by low-dose rifampicin administration, but the extent of the increase was not associated with SLCO1B1 genotype.     

CYP2D6^＊10B基因型对中国人普罗帕酮对映体药动学的影响

AIM: To study the relationship between genotype of CYP2D6*10B and pharmacokinetics of propafenone enantiomers. METHODS: Genotype of 17 healthy Chinese HAN subjects was determined by an allele specific amplification method. The blood samples (0-15 h) of the subjects were taken after oral administration of a single dose (400 mg) of propafenone hydrochloride. Concentrations of propafenone enantiomers in plasma were measured by a reverse-phase HPLC with precolumn derivatization. RESULTS: Seventeen subjects characterized for CYP2D6*10B genotype included (*1/*1) (n=4), (*1/*10) (n=5) and (*10/*10) (n=8). The metabolic ratios (lg MR) of the three genotypes were -2.68+/-0.23, -2.2+/-0.7, and -1.1+/-0.5, respectively. The AUC of the three groups were (1534+/-334), (1891+/-793), (3171+/-1075) microg.h.L(-1) for S-enantiomer and (1136+/-345), (1467+/-817), (2277+/-745) microg.h.L(-1) for R-enantiomer, respectively. The AUC of propafenone enantiomers in *10/*10 is about 1.5-2 times of that of *1/*10 group or *1/*1 group, and the CL of both enantiomers in *10/*10 is only half of that of *1/*10 group or *1/*1 group (P<0.05). CONCLUSION: CYP2D6*10B alleles induce the declined activity of CYP2D6 and impair the metabolism of propafenone.     

Influence of age and cytochrome P450 2C9 genotype on the steady-state disposition of diclofenac and celecoxib

OBJECTIVE: To analyse the influence of age and cytochrome P450 (CYP) 2C9 genotype on the steady-state disposition of the standard NSAID diclofenac and the new COX-2 selective inhibitor celecoxib, both of which are metabolised by the polymorphically expressed CYP2C9. DESIGN: Double-blind randomised crossover study under steady-state conditions. SUBJECTS: 12 young (age 32 +/- 5 years, bodyweight 71 +/- 12kg; mean +/- SD) and 12 elderly (68 +/- 2 years, 82 +/- 15kg) healthy, drug-free, nonsmoking Caucasians of both sexes. METHODS: All subjects received oral celecoxib (200mg twice daily) and diclofenac (75mg twice daily) for 15 days separated by a drug-free interval of at least 3 weeks. Following the last morning dose, multiple blood samples were taken for 25 hours. Concentrations of celecoxib and diclofenac were measured by specific and sensitive high performance liquid chromatography. Identification of CYP2C9 genotype was performed by genomic DNA sequencing. Pharmacokinetic parameters for total and unbound drugs were individually analysed by noncompartmental techniques. RESULTS: For diclofenac, area under the concentration-time curve over the dosage interval (AUC(tau)) was larger in young subjects (3.2 +/- 1.0 mg * h/L) than in older individuals (2.4 +/- 0.4 mg * h/L; p < 0.05). As the terminal half-life (t((1/2)Z)) was very similar in both groups (3.9 +/- 4.4 vs 3.5 +/- 3.3 hours), either less complete absorption in the elderly or their higher bodyweight could account for the difference. For celecoxib, AUC(tau) (5.8 +/- 1.7 vs 5.6 +/- 2.3 mg * h/L) and t((1/2)z) (11.8 +/- 8.7 vs 11.2 +/- 2.9 hours) were almost identical in young and older subjects. Plasma protein binding of both NSAIDs was unaffected by age, and apparent oral clearances for unbound drugs were not different between the two groups of healthy subjects. When considering the genotype of all individuals (CYP2C9*1/*1, n = 10; CYP2C9*1/*2, n = 6; CYP2C9*2/*2, n = 2; CYP2C9*1/*3, n = 4; CYP2C9*3/*3, n = 1), no association with any pharmacokinetic parameter of either drug was apparent. Moreover, there was no significant correlation between the AUC values of celecoxib and diclofenac. CONCLUSIONS: Age and CYP2C9 genotype do not significantly affect the steady-state disposition of celecoxib and diclofenac. This would indicate that both drugs need no dosage reduction in the elderly (at least up to 75 years) and that, besides CYP2C9, additional CYP species contribute to the elimination of both agents.     

The role of CYP2C9 genotype in the metabolism of diclofenac in vivo and in vitro

INTRODUCTION: The polymorphic cytochrome P450 enzyme 2C9 (CYP2C9) catalyses the metabolism of many drugs including S-warfarin, acenocoumarol, phenytoin, tolbutamide, losartan and most of the non-steroidal anti-inflammatory drugs. Diclofenac is metabolised to 4'-hydroxy (OH), the major diclofenac metabolite, 3'-OH and 3'-OH-4'-methoxy metabolites by CYP2C9. The aim of the present study was to clarify the impact of the CYP2C9 polymorphism on the metabolism of diclofenac both in vivo and in vitro. SUBJECTS, MATERIALS AND METHODS: Twenty healthy volunteers with different CYP2C9 genotypes [i.e. CYP2C9*1/ *1 (n = 6), *1/*2 (n = 3), *1,/*3 (n = 5), *2/*3 (n = 4), *21*2 (n = 1), *31*3 (n = 1)] received a single 50-mg oral dose of diclofenac. Plasma pharmacokinetics [peak plasma concentration (Cmax), half-life (t 1/2) and area under the plasma concentration-time curve (AUCtotal)] and urinary recovery of diclofenac and its metabolites were compared between the genotypes. Diclofenac 4'-hydroxylation was also analysed in vitro in 16 different samples of genotyped [i.e. CYP2C9*1/*1 (n = 7), *1/*2 (n=2), *1/*3 (n = 2), *2/*3 (n = 2), *2/*2 (n = 2), *31/*3 (n = 1)] human liver microsomes. RESULTS: Within each genotype group, a high variability was observed in kinetic parameters for diclofenac and 4'-OH-diclofenac (6- and 20-fold, respectively). No significant differences were found between the different genotypes either in vivo or in human liver microsomes. No correlation was found between the plasma AUC ratio of diclofenac/4'-OH-diclofenac and that of losartan/ E-3174, previously determined in the same subjects. CONCLUSION: No relationship was found between the CYP2C9 genotype and the 4'-hydroxylation of diclofenac either in vivo or in vitro. This, together with the lack of correlation between losartan oxidation and diclofenac hydroxylation in vivo raises the question about the usefulness of diclofenac as a CYP2C9 probe.     

Effect of silymarin on the pharmacokinetics of losartan and its active metabolite E-3174 in healthy Chinese volunteers

Purpose  To investigate the effects of silymarin on the pharmacokinetics of losartan and its active metabolite E-3174 and its relationship with CYP2C9 genotypes. Methods  Twelve healthy adult men of known CYP2C9 genotype (six CYP2C9*1/*1 and six CYP2C9*1/*3) were recruited in a two-phase randomized crossover design study. The pharmacokinetics of losartan and E-3174 were measured before and after a 14-day treatment with 140 mg of silymarin three times daily. Results  The area under the plasma concentration–time curve (AUC) of losartan increased significantly following a 14-day silymarin treatment in subjects with the CYP2C9*1/*1 genotype, but not in those with the CYP2C9*1/*3 genotype. The AUC of E-3174 decreased significantly with a silymarin pretreatment in both CYP2C9*1/*1 and the CYP2C9*1/*3 subjects. The metabolic ratio of losartan (ratio of of E-3174 to of losartan) decreased significantly after a 14-day treatment with silymarin in individuals with the CYP2C9*1/*1 genotype (p < 0.05), but not in those with the CYP2C9*1/*3 genotype (p = 0.065). Conclusion  Silymarin inhibits the metabolism of losartan to E-3174, with the magnitude of the interaction differing in individuals with different CYP2C9 genotypes.     

Combined effects of itraconazole and CYP2D6*10 genetic polymorphism on the pharmacokinetics and pharmacodynamics of haloperidol in healthy subjects

This study was to evaluate the combined effects of the CYP3A4 inhibitor itraconazole and the CYP2D6*10 genotype on the pharmacokinetics and pharmacodynamics of haloperidol, a substrate of both CYP2D6 and CYP3A4, in healthy subjects. Nineteen healthy volunteers whose CYP2D6 genotypes were predetermined were enrolled (9 for CYP2D6*1/*1 and 10 for CYP2D6*10/*10). Four subjects (1 for CYP2D6*1/*1 and 3 for CYP2D6*10/*10) did not complete the study because of adverse events. The pharmacokinetics of haloperidol and its pharmacodynamic effects measured for QTc prolongation and neurologic side effects were evaluated after a single dose of 5 mg haloperidol following a pretreatment of placebo or itraconazole at 200 mg/d for 10 days in a randomized crossover manner. Itraconazole pretreatment increased the mean area under the time-concentration curves (AUCs) of haloperidol by 55% compared to placebo pretreatment (21.7 +/- 11.3 vs 33.5 +/- 29.3 ng h/mL). The subjects with CYP2D6*10/*10 genotype showed 81% higher AUC compared to that of subjects with CYP2D6*1/*1 genotype (27.6 +/- 22.2 vs 50.2 +/- 47.1 ng h/mL). In the presence of itraconazole, subjects with CYP2D6*10/*10 showed 3-fold higher AUC of haloperidol compared to that of placebo pretreated subjects with CYP2D6*1/*1 genotype (21.7 +/- 11.3 vs 66.7 +/- 62.1 ng h/mL; P < 0.05). The CYP2D6*10 genotype and itraconazole pretreatment decreased the oral clearance of haloperidol by 24% and 25%, respectively, but without a statistical significance. In the subjects with both CYP2D6*10 genotype and itraconazole pretreatment, however, the oral clearance was significantly decreased to 42% of subjects with wild genotype in the placebo pretreatment (4.7 +/- 3.6 vs 2.0 +/- 1.9 L/h/kg; P < 0.05). Barnes Akathisia Rating Scale (BARS) of subjects with CYP2D6*10/*10 in the presence of itraconazole pretreatment was significantly higher than that of subjects with CYP2D6*1/*1 genotype in the period of placebo pretreatment. Except for this, all other pharmacodynamic estimations did not reach to statistical significance although each CYP2D6*10 genotype and itraconazole pretreatment caused higher value of UKU side effect and BARS scores. The moderate effect of CYP2D6*10 genotype on the pharmacokinetics and pharmacodynamics of haloperidol seems to be augmented by the presence of itraconazole pretreatment.     

Losartan and E3174 pharmacokinetics in cytochrome P450 2C9*1/*1, *1/*2, and *1/*3 individuals

STUDY OBJECTIVE: To determine if differences in the pharmacokinetics of losartan and its pharmacologically active E3174 metabolite exist among individuals expressing the cytochrome P450 (CYP) 2C9*1/*1, *1/*2, and *1/*3 genotypes. DESIGN: Single-dose pharmacokinetic study. SETTING: University general clinical research center. SUBJECTS: Fifteen healthy volunteers, five from each genotype: CYP2C9*1/*1, *1/*2, and *1/*3. INTERVENTION: A single oral dose of losartan 50 mg. MEASUREMENTS AND MAIN RESULTS: Plasma and urine samples were collected for 24 hours, and losartan and E3174 pharmacokinetic data were compared across the three genotypes. Orthostatic blood pressure was measured over 12 hours after dosing. No significant differences were observed among the three groups in losartan or E3174 area under the plasma concentration-time curve, losartan or E3174 elimination half-life, or losartan oral clearance. A significant association between CYP2C9 genotype and losartan to E3174 formation clearance was observed, such that 50% of the variability was accounted for by the genotype. No significant relationship between that genotype and blood pressure was observed at any time. CONCLUSION: Differences in the pharmacokinetics of losartan and its active E3174 metabolite were not observed in healthy subjects with the genotype of CYP2C9*1/*2 and *1/*3 compared with those expressing *1/*1. Alterations in losartan dosing in CYP2C9*1/*2 and *1/*3 individuals does not appear necessary.     

Effect of polymorphic CYP3A5 genotype on the single-dose simvastatin pharmacokinetics in healthy subjects

Simvastatin, a cholesterol-lowering agent, is mainly metabolized by CYP3A4/5. The objective of this study was to investigate the effect of CYP3A5*3 genotype on the pharmacokinetics of simvastatin in humans. Twenty-two men with CYP3A5*1/*1 (n = 4), CYP3A5*1/*3 (n = 8), or CYP3A5*3/*3 (n = 10) genotypes were enrolled. Each subject ingested a 20-mg dose of simvastatin, and plasma simvastatin concentrations were measured for 12 hours after dosing. The mean (+/-SD) area under the plasma concentration-time curve for simvastatin in the CYP3A5*1/*1 carriers (4.94 +/- 2.25 ng x h/mL) was significantly lower than CYP3A5*3/*3 carriers (16.35 +/- 6.37 ng x h/mL; P = .013, Bonferroni test). The mean (+/-SD) oral clearance was also significantly different between CYP3A5*1/*1 carriers (4.80 +/- 2.35 L/h) and CYP3A5*3/*3 carriers (1.35 +/- 0.61 L/h; P < .05, Dunn's test). However, other pharmacokinetic parameters including peak plasma concentrations and half-life did not show any difference between genotype groups. These findings suggest that the polymorphic CYP3A5 gene affects the disposition of simvastatin and provides a plausible explanation for interindividual variability of simvastatin disposition.     

Effect of the single CYP2C9*3 allele on pharmacokinetics and pharmacodynamics of losartan in healthy Japanese subjects

Objective Losartan is metabolized to the active carboxylic acid metabolite EXP3174 by CYP2C9. In this study, we determined the effects of the single CYP2C9*3 variant on the pharmacokinetics and pharmacodynamics of losartan.Methods Seven healthy Japanese subjects (CYP2C9*1/*1, n=4 and CYP2C9*1/*3, n=3) were phenotyped with a single dose of losartan (25 mg). Blood and urine samples were collected and assayed for losartan and EXP3174. Blood pressure and pulse rate were also measured using a sphygmomanometer.Results The maximum plasma concentration of EXP3174 was significantly (P<0.05) lower in the CYP2C9*1/*3 (n=3) group than in the CYP2C9*1/*1 (n=4) group. Diastolic blood pressure in the CYP2C9*1/*1 group, but not that in the CYP2C9*1/*3 group except for at 6 h and 8 h, was reduced from 1.5 h to 12 h compared with the baseline level. Systolic blood pressure in the CYP2C9*1/*1 group, but not that in the CYP2C9*1/*3 group, was reduced from 1 h to 12 h compared with the baseline level. The metabolic ratio (MR) of EXP3174 concentration to the losartan concentration in plasma at 6 h post-dosing and the 4-h to 8-h urinary EXP3174/losartan MR were significantly lower in the CYP2C9*1/*3 group than in the CYP2C9*1/*1 group. The plasma 6-h MR and the 4-h to 8-h urinary MR were significantly (P<0.05) correlated with the plasma AUC ratio (AUC_EXP3174/AUC_losartan), with Spearman rank correlation coefficients of 0.75 and 0.89, respectively.Conclusion The single CYP2C9*3 variant reduces the metabolism of losartan and its hypotensive effect. Plasma MR, as well as urine MR, may be useful for phenotyping assays of CYP2C9 activity.     

Effects of the SLCO1B1*15 allele on the pharmacokinetics of pitavastatin

The hepatic uptake of pitavastatin is mediated by carriers, especially OATP1B1, which is encoded by the SLCO1B1 gene. Because the liver is a target organ of pitavastatin, OATP1B1 is responsible for both the pharmacological effects and clearance of pitavastatin. The effects of the SLCO1B1*15 allele on the pharmacokinetics (PK) of pitavastatin were studied. Pitavastatin 2 mg was orally administered to 38 subjects with SLCO1B1*1a/*1b (n = 20), *1b/*15 (n = 13), or *15/*15 (n = 5). After pitavastatin administration, the plasma concentrations of pitavastatin and pitavastatin lactone were assayed for up to 48 h using liquid chromatography-tandem mass spectrometry. In comparison to the SLCO1B1*1a/*1b subjects, only a C(max) was slightly higher in the SLCO1B1*1b/*15 subjects. However, the SLCO1B1*15/*15 subjects had a 1.74-fold higher AUC(inf) (285.5 ± 14.5 vs. 164.6 ± 41.3 ng·h/mL; p < 0.001), a 2.21-fold higher C(max) (106.7 ± 15.1 vs. 48.3 ± 13.4 ng/mL; p < 0.001), and a 47.3% lower apparent oral clearance (13.1 ± 3.9 vs. 6.9 ± 0.4 L/h; p < 0.001) of pitavastatin. For pitavastatin lactone, there were no significant differences in AUC(inf), C(max), t(1/2), and t(max) among the three genotypes. Unlike previous studies, the disposition of pitavastatin exposure was not altered in subjects with the SLCO1B1*1b/*15 genotype, except C(max). However, pitavastatin exposure was significantly increased in subjects with the SLCO1B1*15/*15 genotype due to reduced hepatic absorption.     

Effects of the CYP2C9*13 allele on the pharmacokinetics of losartan in healthy male subjects

1. The aim of the study was to determine the pharmacokinetics of losartan in relation to the CYP2C9*13 allele.

2. A single oral dose of 50?mg losartan was administrated to each of the 16 healthy male volunteers with a different genotype (CYP2C9*1/*1, n?=?6; CYP2C9*1/*13, n?=?4; and CYP2C9*1/*3, n?=?6). Blood samples were collected from pre-dose up to 24?h after the drug administration. Plasma losartan and E3174 (an active metabolite of losartan) were assayed by liquid chromatography-tandem mass spectrometry (LC-MS/MS).

3. All the subjects finished the study without adverse drug effects. In the present study, the frequencies of CYP2C9*13 and *13 alleles were 0.6% and 2.6% in Chinese healthy volunteers, respectively, and both alleles were in Hardy–Weinberg equilibrium. Compared with the subjects in the CYP2C9*1/*1 group, individuals carrying the CYP2C9*1/*13 genotype showed significantly a longer t_1/2 of losartan and E3174 and markedly increased the area under the curve (AUC) of losartan. Meanwhile, the CYP2C9*1/*3 genotype group had significant differences in t_1/2 and C_max of E3174 compared with the CYP2C9*1/*1 group. The ratio of AUC_E3174/AUC_losartan after losartan administration in the CYP2C9*1/*13 and CYP2C9*1/*3 groups was also statistically different from that in the CYP2C9*1/*1 group.

4. The data indicate that the presence of the CYP2C9*13 allele results in poor metabolism of losartan after a single oral dose.

     

Lornoxicam pharmacokinetics in relation to cytochrome P450 2C9 genotype

AIMS: To investigate the pharmacokinetics of lornoxicam and the relationship with CYP2C9 polymorphism in healthy Chinese subjects. METHODS: A single oral dose of 8 mg lornoxicam was administered to 18 healthy Chinese male subjects. Plasma was sampled for 24 h post dose, and plasma concentrations of lornoxicam were measured using a validated LC/MS/MS method. CYP2C9 genotype was determined by polymerase chain reaction-based restriction fragment length polymorphism or by direct sequencing of the coding region of the CYP2C9 gene. RESULTS: Of the 18 subjects, one subject was found to be a very poor metabolizer of lornoxicam with a long t(1/2) of 106 h, a low CL/F of 0.71 ml min(-1), and a high AUC(0-infinity) of 187.6 microg ml(-1) h. Genotyping studies revealed that this subject was heterozygous for CYP2C9*3 and a new variant CYP2C9 allele. Of the other 17 subjects, 13 were *1/*1 carriers, three were *1/*3 carriers, and one was a *1/*2 carrier. Mean AUC(0-infinity) values (95% confidence intervals) of lornoxicam were 9.25 (6.55, 11.95) vs. 4.75 (3.55, 5.95) microg ml(-1) h in *1 heterozygotes vs.*1 homozygotes, and mean CL/F values were 14.8 (10.2, 19.4) vs. 32.9 (24.5, 41.3) ml min(-1), respectively (P < 0.05 for both AUC and CL/F). CONCLUSIONS: The results show that the pharmacokinetics of lornoxicam are dependent on CYP2C9 polymorphism. In particular, the presence of the CYP2C9*3 allele impairs the oral clearance of lornoxicam.     

Herbal medicine yin zhi huang induces CYP3A4-mediated sulfoxidation and CYP2C19-dependent hydroxylation of omeprazole

Aim： To explore the potential interactions between Y/n Zhi Huang （YZH） and omeprazole, a substrate of CYP3A4 and CYP2C19. Methods： Eighteen healthy volunteers, including 6 CYP2C19＊ 1/＊ 1, 6 CYP2C19＊1/＊2 or ＊3 and 6 CYP2C19＊2/ ＊2 were enrolled in a 2-phase, randomized, crossover clinical trial. In each phase, the volunteers received either placebo or 10 mL YZH oral liquid, 3 times daily for 14 d. Then all the patients took a 20 mg omeprazole capsule orally. Blood samples were collected up to 12 h after omeprazole administration. Plasma concentrations of omeprazole and its metabolites were quantified by HPLC with UV detection. Results： After 14 d of treatment of YZH, plasma omeprazole significantly decreased and those of omeprazole sulfone and 5-hydroxyomeprazole significantly increased. The ratios of the area under the plasma concentration-time curves from time 0 to infinity （AUC（0-∞） of omeprazole to 5-hydroxyomprazole and those of omeprazole to omeprazole sulfone decreased by 64.80%＋ 12.51% （P= 0.001） and 63.31%＋ 18.45 % （P=0.004） in CYP2C 19＊ 1/＊ 1, 57.98 %± 14.80% （P=0.002） and 54.87%±18.42% （P=0.003） in CYP2C19＊1/＊2 or ＊3, and 37.74%±16.07% （P= 0.004） and 45.16%±15.54% （P=0.003） in CYP2C19＊2/＊2, respectively. The decrease of the AUC（0-∞） ratio of omeprazole to 5-hydroxyomprazole in CYP2C19＊ 1/＊ 1 and CYP2C19＊1/＊2 or ＊3 was greater than those in CYP2C19＊2/＊2 （P=0.047 and P=0.009）. Conclusion： YZH induces both CYP3A4-catalyzed sulfoxidation and CYP2C19-dependent hydroxylation of omeprazole leading to decreases in plasma omeprazole concentrations.     

Effect of cyp2d6*10 allele on the pharmacokinetics of loratadine in chinese subjects.

Loratadine is known to be a substrate for both CYP3A4 and CYP2D6 based on a previous in vitro study. In view of the large interindividual variability in loratadine pharmacokinetics and the greater genetically determined variability of CYP2D6 activity than of CYP3A4 in vivo, we hypothesized that CYP2D6 polymorphisms may contribute to the pharmacokinetic variability of loratadine. The purpose of this study was to evaluate the effect of CYP2D6 genotype (specifically the CYP2D6*10 allele) on the pharmacokinetics of loratadine in Chinese subjects. Three groups of healthy male Chinese subjects were enrolled: group I, homozygous CYP2D6*1 (*1/*1, n=4); group II, heterozygous CYP2D6*10 (*1/*10 or *2/*10, n=6); and group III, homozygous CYP2D6*10 (*10/*10, n=7) carriers. Each subject received a single oral dose of 20 mg of loratadine under fasting conditions. Multiple blood samples were collected over 48 h, and the plasma concentrations of loratadine and its metabolite desloratadine were determined by high-performance liquid chromatography. In comparing homozygous CYP2D6*10 (group III) to heterozygous CYP2D6*10 (group II) to homozygous CYP2D6*1 (group I) subjects, loratadine oral clearance values were 7.17+/- 2.54 versus 11.06+/-1.70 versus 14.59+/-2.43 l/h/kg, respectively [one-way analysis of variance (ANOVA), p<0.01], and the corresponding metabolic ratios [area under the plasma concentration-time curve (AUC)(desloratadine)/AUC(loratadine)] were 1.55+/-0.73 versus 2.47+/- 0.46 versus 3.32+/- 0.49, respectively (one-way ANOVA, p<0.05), indicating a gene-dose effect. The results demonstrated that CYP2D6 polymorphism prevalent in the Chinese population significantly affected loratadine pharmacokinetics.     

Differences in flurbiprofen pharmacokinetics between CYP2C9*1/*1, *1/*2, and *1/*3 genotypes

OBJECTIVE: This study was conducted to examine differences in flurbiprofen metabolism among individuals with the CYP2C9*1/*1, *1/*2, and *1/*3 genotypes. METHODS: Fifteen individuals with the CYP2C9*1/*1 ( n=5), *1/*2 ( n=5), and *1/*3 ( n=5) genotypes received a single 50-mg oral dose of flurbiprofen. Plasma and urine samples were collected over 24 h, and flurbiprofen and 4'-hydroxyflurbiprofen pharmacokinetic data were compared across genotypes. RESULTS: CYP2C9 genotype was a significant predictor of flurbiprofen metabolism and accounted for 59% of the variability in flurbiprofen AUC(0- infinity ), and approximately 50% of the variability in flurbiprofen oral clearance, formation clearance to 4'-hydroxyflurbiprofen, and the 0 to 24-h urinary metabolic ratio of flurbiprofen to 4'-hydroxyflurbiprofen. Flurbiprofen AUC(0- infinity )was significantly higher and all measures of flurbiprofen clearance were significantly lower in the CYP2C9*1/*3 individuals than in those with *1/*1. Significant differences in these parameters were not detected between *1/*2 subjects and *1/*1 subjects. CONCLUSIONS: CYP2C9 genotype is a significant predictor of flurbiprofen disposition in humans by altering CYP2C9-mediated metabolism and reducing systemic clearance. The effects are most pronounced in individuals carrying the *3 allele.     

Influence of SLCO1B1 Polymorphisms on the Drug-Drug Interaction Between Darunavir/Ritonavir and Pravastatin

The authors investigated whether SLCO1B1 polymorphisms contribute to variability in pravastatin pharmacokinetics when pravastatin is administered alone versus with darunavir/ritonavir. HIV-negative healthy participants were prospectively enrolled on the basis of SLCO1B1 diplotype: group 1 (*1A/*1A, n = 9); group 2 (*1A/*1B, n = 10; or *1B/*1B, n = 2); and group 3 (*1A/*15, n = 1; *1B/*15, n = 5; or *1B/*17, n = 1). Participants received pravastatin (40 mg) daily on days 1 through 4, washout on days 5 through 11, darunavir/ritonavir (600/100 mg) twice daily on days 12 through 18, with pravastatin 40 mg added back on days 15 through 18. Pharmacokinetic studies were conducted on day 4 (pravastatin alone) and day 18 (pravastatin + darunavir/ritonavir). Pravastatin area under the plasma concentration-time curve (AUC(tau)) was 21% higher during administration with darunavir/ritonavir compared with pravastatin alone; however, this difference was not statistically significant (P = .11). Group 3 variants had 96% higher pravastatin AUC(tau) on day 4 and 113% higher pravastatin AUC(tau) on day 18 compared with group 1. The relative change in pravastatin pharmacokinetics was largest in group 3 but did not differ significantly between diplotype groups. In sum, the influence of SLCO1B1*15 and *17 haplotypes on pravastatin pharmacokinetics was maintained in the presence of darunavir/ritonavir. Because OATP1B1 inhibition would be expected to be greater in carriers of normal or high-functioning SLCO1B1 haplotypes, these findings suggest that darunavir/ritonavir is not a potent inhibitor of OATP1B1-mediated pravastatin transport in vivo.     

Effect of CYP2C9 and SLCO1B1 polymorphisms on the pharmacokinetics and pharmacodynamics of nateglinide in healthy Chinese male volunteers

Purpose

Nateglinide is commonly used in the treatment of patients with type 2 diabetes mellitus. Our objective was to assess the association between CYP2C9 and SLCO1B1 polymorphisms and the metabolism of nateglinide in healthy Chinese male volunteers.

Methods

A total of 35 healthy Chinese male volunteers with different CYP2C9 and SLCO1B1 genotypes were given a single oral dose of 120 mg nateglinide. Plasma concentrations of nateglinide and blood glucose level were measured up to 8 h.

Results

In subjects with the CYP2C9*1/*3 & 521TT, CYP2C9*1/*1 & 521TC/CC and CYP2C9*1/*3 & 521TC genotype, AUC_0-∞ of nateglinide was 56 %, 34 % and 56 % higher (P?=?0.002, P?=?0.041 and P?=?0.013, respectively), and the CL/F of nateglinide was 35 %, 11 % and 36 % lower (P?=?0.000, P?=?0.003 and P?=?0.002, respectively) than that in the reference group. When only considering 521 T>C polymorphism, it had no significant association with the pharmacokinetics of nateglinide. CYP2C9*3 and 521 T>C polymorphisms were the significant predictors of the AUC_0-∞ and CL/F of nateglinide (adjusted multiple R ² ?=?34 % and 43 %, respectively) according to multiple linear regression analyses, but they have no significant association with changes in the blood glucose-lowering effect of nateglinide.

Conclusions

Both SLCO1B1 521 T>C and the CYP2C9*3 polymorphisms can significantly affect the pharmacokinetics of nateglinide, but they could only partially explain the interindividual variability of plasma concentration of nateglinide. Moreover, 521 T>C and the CYP2C9*3 polymorphisms have no effect on pharmacodynamics of nateglinide in healthy Chinese male subjects.     

Influence of CYP2C9*2 genetic polymorphism on pharmacokinetics of losartan and its active metabolite E-3174 on the background of CYP3A4 wild genotype in healthy Chinese Hui subjects

In the present study, we aimed to investigate the influence of CYP2C9*2 genetic polymorphism on pharmacokinetics of losartan and its active metabolite E-3174 on the background of CYP3A4 wild genotype in healthy Chinese Hui subjects. Blood samples were collected from subjects for CYP2C9 and CYP3A4 genotyping using a polymerase chain reaction-restriction fragmentlength polymorphism (PCR-RFLP) assay. A pharmacokinetic study was then carried out in two groups with CYP2C9*1/*1 (n = 8) andCYP2C9*1/*2 (n = 6) genotypes at the same time, and all the 14 subjects were CYP3A4 wildgenotype. Plasma levels of losartan and E-3174 were determined by high-performance liquid chromatography-fluorescence (HPLC-FLD) method before and after a single oral dose of 50-mg dose of losartan in tablet form. The pharmacokinetic parameters were calculated by DAS 2.0 software and analyzed by SPSS 16.0 software. Pharmacokinetic parameters, including area under the curve from 0 h to the last measured point 24 h (AUC_0–24), area under the curve from 0 h to infinite time (AUC_0–∞), peak plasma concentration (C_max), time to reach C_max (t_max), oral clearance (CL), oral volume of distribution (V_d) and elimination half-life (t_1/2), were determined. Compared with the CYP2C9*1/*2 group, the AUC_0–24, AUC_0–∞ and C_max of E-3174 in CYP2C9*1/*1 group of Hui subjects were respectively 1.36, 1.32 and 1.64 times more, and the statistic differences were significant (P<0.05). The CYP2C9*2 mutant allele played an important role in the pharmacokinetics of losartan after oral administration, and itmight decrease the generationof E-3174. However, large-sample clinical trials are required to validate whether the dose adjustment according to CYP2C9 genotype is necessary.     

黄豆苷元对不同基因型健康受试者氯沙坦药代动力学的影响

目的 探讨黄豆苷元对不同基因型健康受试者氯沙坦药代动力学的影响.方法 筛选中国男性健康受试者18名(CYP2C9*1/*1、CYP2C9*1/*3、CYP2C9*1/*13基因型各6名).执行双周期、自身前后对照方案,第一阶段随机分为对照组和试验组,受试者分别口服黄豆苷元片或安慰剂15 d,第15天两组受试者均口服氯沙...