甘草与甘遂配伍毒性成分的研究

甘草与甘遂合用有很大毒性。本文将二者配伍后的乙酸乙酯、乙醇、水提取液进行了毒性试验,采用柱层析、制备性薄层层析对毒性成分进行了分离。经化合物定性鉴别试验表明,甘草、甘遂合用后产生的毒性成分为三种黄酮甙类化合物。     

甘遂与甘草合用对大鼠肝药酶CYP1A2、CYP2C19和CYP2E1的影响

<正>"十八反"则告诫人们,甘遂(Euphorbia kansui,EK)与甘草(Glycyrrhiza uralensis,GU)相对立不宜伍用。但有学者认为,反药同用能相反相成,产生较强的功效。故一直以来,甘遂与甘草组合在临床上仍有广泛的应用~([1-3])。近年来,中药用药的安全性问题越来越受到重视,阐明"反"的机制,已成为中医药理论自身发展的必然要求。药物相互作用中最常见的原因是CYP450的诱导和抑制~([4-5])。中药虽然成分复杂,但效应成分多数仍要通过     

CYP2C9、CYP2C19、CYP3A4基因多态性对磺脲类降糖药代谢的影响

磺脲类口服降糖药在人体内主要经过肝脏代谢。肝脏中的细胞色素氧化酶P450是一种重要的药物代谢酶系统,在人群中存在基因多态性,导致药物疗效和不良反应在个体间存在着较大的差异。本文将对CYP450中的几种重要的代谢酶亚型CYP2C9、CYP2C19、CYP3A4的基本结构、基因多态性、种族差异及其对磺脲类降糖药代谢的影响作一综述。     

CYP2B和CYP3A参与药物代谢的影响因素及对氯胺酮代谢的影响

目的:为进一步研究氯胺酮在成瘾动物体内代谢动力学规律及细胞色素P_(450)活性的调控和相关性研究提供参考。方法:以"细胞色素P_(450)""性别""氯胺酮""CYP2B""CYP3A""Sex""Ketamine"等为关键词,组合查询1980-2016年在Pub Med、Elsevier、中国知网、万方、维普等数据库中的相关文献,对CYP2B和CYP3A参与药物代谢的诱导、抑制和性别等影响因素及对氯胺酮代谢的影响进行综述。结果与结论:共检索到相关文献256篇,其中有效文献62篇。CYP2B和CYP3A是重要的细胞色素P_(450),二者参与代谢了临床大多数药物,包括氯胺酮。诱导、抑制和性别差异等因素主要是通过改变细胞色素P_(450)的基因表达和蛋白表达来影响药物在动物体内代谢的。氯胺酮是一种被广泛滥用的药物,具有成瘾性和个体的耐受差异性。通过研究细胞色素P_(450)的基因表达和蛋白表达有利于指导研究氯胺酮在成瘾动物体内的特殊代谢动力学规律,以及为阐释成瘾动物体内的细胞色素P_(450)活性的调控机制和相关性研究提供理论支持。     

马钱子碱与甘草次酸、甘草苷配伍后对大鼠肝脏CYP450的影响(英文)

马钱子碱每日低、中、高(3,15和60 mg·kg-1)剂量以及高剂量马钱子碱和甘草次酸(每日25 mg·kg-1)、甘草苷(每日20 mg·kg-1)配伍,分别对Wistar大鼠连续灌胃给药7天后,检测不同给药组对CYP3A、CYP1A2、CYP2E1和CYP2C的酶活性和mRNA表达的影响。与对照组相比,高剂量马钱子碱使CYP3A活性下降24.5%,CYP2C的活性下降34.6%,而使CYP2E1的活性提高了146.1%。另一方面,与高剂量组相比,甘草次酸配伍组使CYP2E1的活性降低了51.4%,CYP1A2的活性降低了33.5%;甘草苷配伍组使CYP2E1的活性降低了41.1%,CYP2C的活性降低了37.7%。实验结果表明,马钱子碱和甘草次酸、甘草苷配伍后,可以在一定程度上影响上述CYP450酶的mRNA表达和酶活性。因此推测配伍后甘草苷对马钱子碱所致CYP450酶异常变化的拮抗作用,以及甘草次酸对CYP2E1和CYP1A2活性的抑制作用,可能是甘草降低马钱子毒性的重要机制之一。     

银杏叶提取物对细胞色素P450影响的研究进展

银杏叶提取物(Ginkgo biloba extract,GBE)是目前使用最为广泛的中草药之一。GBE与其他药物合用是否产生药物相互作用得到关注。GBE与其他药物合用,可能通过影响肝药酶的活性发生药物相互作用,其中GBE对肝药酶的诱导或抑制作用的研究较为深入。本综述回顾了近年来报道的关于GBE对细胞色素P450 CYP3A4、CYP2C9、CYP1A2、CYP2C19的影响。     

CYP2C9和CYP2C19基因多态性对药物代谢的影响及个体化用药研究进展

CYP2C9、CYP2C19酶是细胞色素P450系统中重要的药物代谢酶,共同参与许多重要药物的体内代谢。CYP2C9、CYP2C19基因具有高度多态性,在基因编码区和非编码区存在许多碱基突变,这种突变会影响酶的活性,导致酶底物药物清除率改变,从而导致药品不良反应的发生。本文对CYP2C9、CYP2C19基因突变的发生频率及对药物代谢的影响做详细阐述。     

甘草与甘遂的配伍对大鼠肠黏膜P-gp的影响

评价甘草与甘遂配伍对大鼠肠黏膜P糖蛋白 (P-glycoprotein) 的影响。通过对大鼠口服甘草煎液、甘遂煎液、甘草甘遂合煎液及其合并液1周后, 使用垂直型扩散池 (ussing chamber) 技术, 体外评价罗丹明123 (rhodamine123, R123) 和荧光素钠 (fluorescein sodium, CF) 经大鼠空肠黏膜的经时吸收方向和分泌方向的透过量和表观渗透系数。R123和CF在接受室的浓度用荧光分光光度计检测。应用实时荧光定量聚合酶链式反应技术 (real-time fluorescent quantitative polymerase chain reaction) 检测mdr1a基因在肠黏膜中的表达。在ussing chamber实验中, 4种药液除甘草外均具有增加R123经吸收方向 (mucosa to serosa, M-S) 透过性和减少分泌方向 (serosa to mucosa, S-M) 透过性的趋势。甘草只增加了R123吸收方向的透过, 但对分泌方向影响不大, 且均无统计学意义; 甘遂组与合煎组均使R123 S-M透过明显减少 (P < 0.01); 合并组明显增加了R123 M-S的透过 (P < 0.05)。各组的泵出比均明显降低 (P < 0.05)。而rt-pcr实验中, 评价甘遂对肠黏膜的P-gp活性的影响时, 发现大鼠灌胃7 d和14 d甘遂后, 与对照组相比都有下调mdr1a表达的趋势, 但是没有统计学意义。另外, 在评价甘草与甘遂对旁细胞转运CF影响的实验中, 甘遂组、合煎组和合并组均明显减少了CF S-M的透过 (P < 0.01); 甘遂组、合煎组和合并组则均明显减少了CF M-S的透过 (P < 0.05), 但甘草对CF转运的影响没有统计学意义。甘遂可能是一种P-gp抑制剂, 而甘草与甘遂合用后对R123透过的影响与单用甘遂相似, 可能是甘草与甘遂有协同作用, 使其毒性成分吸收增加, 这可能是两者配伍产生毒性的机制之一。     

海藻、大戟、甘遂和芫花分别与不同剂量的甘草配伍对小鼠肠功能的影响

目的探讨海藻、大戟、甘遂和芫花分别与不同剂量的甘草配伍对肠功能的影响。方法采用均匀设计进行分组。小鼠分别ig给予海藻甘草、大戟甘草、甘遂甘草或芫花甘草合煎液1次,分别于给药后20,60,30和20min后,再ig给予5%印度墨汁混悬液0.2ml。给予墨汁20min后处死小鼠,测定小肠推进率(IPR)。结果大戟甘草合煎液组小鼠在总给药剂量0～30g·kg-1范围内且总给药剂量一定时,随甘草剂量的增加小鼠IRP降低(R=0.7853,P<0.05)。芫花甘草合煎液组总给药剂量低于5g·kg-1时,小鼠IRP未见明显变化;总给药剂量>5g·kg-1且一定时,小鼠IRP随甘草呈剂量依赖性增加(R=0.8414,P<0.05)。海藻甘草合煎液和甘遂甘草合煎液组海藻和甘遂与甘草配伍比例的变化对IRP无明显影响。结论在一定的总给药剂量范围内,大戟甘草合煎液对小鼠肠功能的影响与配伍比例密切相关,甘草剂量增加时小鼠肠功能减弱。芫花甘草合煎液对小鼠肠功能的影响也与配伍比例密切联系,甘草剂量增加时肠功能增强。     

甘草与大戟甘遂芫花配伍对大鼠肝脏细胞色素P4501A2酶活性的影响

目的研究甘草与大戟、甘遂、芫花合用对细胞色素P450(CYP)1A2酶活性的影响。方法采用高效液相色谱法测定CYP1A2活性。结果单用甘草诱导CYP1A2的酶活性;大戟、甘遂、芫花单用抑制CYP1A2的酶活性;甘草与大戟、甘遂、芫花合用后抑制了CYP1A2的酶活性。结论甘草与大戟、甘遂、芫花合用对CYP1A2酶活性的抑制作用主要是由大戟、甘遂、芫花引起的。     

Contribution of CYP2C9, CYP2A6, and CYP2B6 to valproic acid metabolism in hepatic microsomes from individuals with the CYP2C9*1/*1 genotype.

The present study investigated the role of specific human cytochrome P450 (CYP) enzymes in the in vitro metabolism of valproic acid (VPA) by a complementary approach that used individual cDNA-expressed CYP enzymes, chemical inhibitors of specific CYP enzymes, CYP-specific inhibitory monoclonal antibodies (MAbs), individual human hepatic microsomes, and correlational analysis. cDNA-expressed CYP2C9*1, CYP2A6, and CYP2B6 were the most active catalysts of 4-ene-VPA, 4-OH-VPA, and 5-OH-VPA formation. The extent of 4-OH-VPA and 5-OH-VPA formation by CYP1A1, CYP1A2, CYP1B1, CYP2C8, CYP2C19, CYP2D6, CYP2E1, CYP4A11, CYP4F2, CYP4F3A, and CYP4F3B was only 1-8% of the levels by CYP2C9*1. CYP2A6 was the most active in catalyzing VPA 3-hydroxylation, whereas CYP1A1, CYP2B6, CYP4F2, and CYP4F3B were less active. Correlational analyses of VPA metabolism with CYP enzyme-selective activities suggested a potential role for hepatic microsomal CYP2A6 and CYP2C9. Chemical inhibition experiments with coumarin (CYP2A6 inhibitor), triethylenethiophosphoramide (CYP2B6 inhibitor), and sulfaphenazole (CYP2C9 inhibitor) and immunoinhibition experiments (including combinatorial analysis) with MAb-2A6, MAb-2B6, and MAb-2C9 indicated that the CYP2C9 inhibitors reduced the formation of 4-ene-VPA, 4-OH-VPA, and 5-OH-VPA by 75-80% in a panel of hepatic microsomes from donors with the CYP2C9*1/*1 genotype, whereas the CYP2A6 and CYP2B6 inhibitors had a small effect. Only the CYP2A6 inhibitors reduced VPA 3-hydroxylation (by approximately 50%). The extent of inhibition correlated with the catalytic capacity of these enzymes in each microsome sample. Overall, our novel findings indicate that in human hepatic microsomes, CYP2C9*1 is the predominant catalyst in the formation of 4-ene-VPA, 4-OH-VPA, and 5-OH-VPA, whereas CYP2A6 contributes partially to 3-OH-VPA formation.     

The hydroxylation of omeprazole correlates with S-mephenytoin and proguanil metabolism

Objectives: This pharmacogenetic study was aimed at studying the pattern of oxidation of omeprazole in a Turkish population and testing whether omeprazole metabolism cosegregates with the genetically determined metabolism of mephenytoin and proguanil in Turkish subjects. Methods: The hydroxylation of omeprazole was measured in 116 unrelated healthy Turkish subjects after administration of a single oral dose of omeprazole (20 mg), using the ratio of omeprazole to 5-hydroxyomeprazole in plasma 3 h after dosing. To 31 subjects, who were phenotyped with omeprazole, mephenytoin (100 mg, p.o.) or proguanil (200 mg, p.o.) were administered at least 1 week apart. The S/R ratio of mephenytoin and the ratio of proguanil to cycloguanil were determined from an 8-h urine collection. Results: Based on the distribution of the log (omeprazole/hydroxyomeprazole) values and using the antimode value of 0.8, the frequency of poor metabolizers of omeprazole was estimated to be 7.7% (95% confidence interval 3–18%) which was similar to that in the other Caucasian populations (P = 0.54, Fisher's exact test). Three poor metabolizers of omeprazole were also classified as poor metabolizers of both mephenytoin and proguanil and no misclassification occurred with three phenotyping methods. All three methods separated poor or extensive metabolizer phenotypes with complete concordance. The ratio of omeprazole to hydroxyomeprazole correlated with the S/R ratio of mephenytoin and the ratio of proguanil to cycloguanil. Conclusion: These results support the hypothesis that the oxidative metabolism of three different drugs may be catalyzed by the same cytochrome P450 enzyme. Received: 12 February 1997 / Accepted in revised form: 23 July 1997     

Different inhibitory effect of fluvoxamine on omeprazole metabolism between CYP2C19 genotypes

AIMS: Omeprazole is mainly metabolized by the polymorphic cytochrome P450 (CYP) 2C19. The inhibitory effect of fluvoxamine, an inhibitor of CYP2C19 as well as CYP1A2, on the metabolism of omeprazole was compared between different genotypes for CYP2C19. METHODS: Eighteen volunteers, of whom six were homozygous extensive metabolizers (EMs), six were heterozygous EMs and six were poor metabolizers (PMs) for CYP2C19, participated in the study. A randomized double-blind, placebo-controlled crossover study was performed. All subjects received two six-day courses of either daily 50 mg fluvoxamine or placebo in a randomized fashion with a single oral 40 mg dose of omeprazole on day six in both cases. Plasma concentrations of omeprazole and its metabolites, 5-hydroxyomeprazole, omeprazole sulphone, and fluvoxamine were monitored up to 8 h after the dosing. RESULTS: During placebo administration, geometric means of peak concentration (C(max)), under the plasma concentration-time curve from 0 to 8 h (AUC(0,8 h)) and elimination half-life (t(1/2)) of omeprazole were 900 ng ml(-1), 1481 ng ml(-1) h, and 0.6 h in homozygous EMs, 1648 ng ml(-1), 4225 ng ml(-1) h, and 1.1 h in heterozygous EMs, and 2991 ng ml(-1), 11537 ng ml(-1) h, and 2.8 h in PMs, respectively. Fluvoxamine treatment increased C(max) of omeprazole by 3.7-fold (95%CI, 2.4, 5.0-fold, P < 0.01) and 2.0-fold (1.4, 2.6-fold, P < 0.01), AUC(0,8 h) by 6.0-fold (3.3, 8.7-fold, P < 0.001) and 2.4-fold (1.7, 3.2-fold, P < 0.01), AUC(0, infinity ) by 6.2-fold (3.0, 9.3-fold, P < 0.01) and 2.5-fold (1.6, 3.4-fold, P < 0.001) and prolonged t((1/2)) by 2.6-fold (1.9, 3.4-fold, P < 0.001) and 1.4-fold (1.02, 1.7-fold, P < 0.05), respectively. However, no pharmacokinetic parameters were changed in PMs. The AUC(0,8 h) ratios of 5-hydroxyomeprazole to omeprazole were decreased with fluvoxamine in homozygous EMs (P < 0.05) and heterozygous EMs (P < 0.01). CONCLUSIONS: Even a low dose of fluvoxamine increased omeprazole exposure in EMs, but did not increase omeprazole exposure in PMs after a single oral dose of omeprazole. These findings confirm a potent inhibitory effect of fluvoxamine on CYP2C19 activity. The bioavailability of omeprazole might, to some extent, be increased through inhibition of P-glycoprotein during fluvoxamine treatment.     

Stereoselective metabolism of rabeprazole-thioether to rabeprazole by human liver microsomes

Objective Rabeprazole is metabolized mainly non-enzymatically to rabeprazole-thioether. This in vitro study was designed to clarify the stereoselective oxidation mechanism and to identify the enzyme(s) involved in the metabolic breakdown of rabeprazole-thioether to rabeprazole. Methods Rabeprazole-thioether was incubated with human liver microsomes and several recombinant cytochrome P450 (CYP) enzymes (CYPs 1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1, and 3A4). High-performance liquid chromatography was used for identification and quantification of each rabeprazole enantiomer. Results The K _m and V _max values for the formation of (R)-rabeprazole from rabeprazole-thioether in human liver microsomes were 6.6 μM and 92 pmol/min/mg protein, respectively, whereas those for the formation of (S)-rabeprazole were 5.1 μM and 21 pmol/min/mg protein, respectively. CYP3A4 was found to be the major enzyme responsible for (R)- and (S)-rabeprazole formation from rabeprazole-thioether. The intrinsic clearance (V _max /K _m ) for the oxidation by CYP3A4 of (R)-rabeprazole was 3.5-fold higher than that for the (S)-enantiomer (81 nl/min/pmol of P450 vs. 23 nl/min/pmol of P450). On the other hand, CYP2C19 and CYP2D6 were the main enzymes catalyzing the formation of desmethylrabeprazole-thioether from rabeprazole-thioether. The mean K _m and V _max values of desmethylrabeprazole-thioether formation for CYP2C19 were 5.1 μM and 600 pmol/min/nmol of P450, respectively, whereas those for CYP2D6 were 15.1 μM and 736 pmol/min/nmol of P450, respectively. Discussion Rabeprazole is reduced mainly non-enzymatically to rabeprazole-thioether, which is further stereoselectively re-oxidized by CYP3A4 mainly to (R)-rabeprazole. The difference in the enantioselective disposition of rabeprazole is determined by stereoselectivity in CYP3A4-mediated metabolic conversion from rabeprazole-thioether to rabeprazole.     

Effect of CYP2C19*2 and *17 mutations on pharmacodynamics and kinetics of proton pump inhibitors in Caucasians

AIMS

To investigate the impact of CYP2C19 mutations *2-*6 and *17 on acid-inhibition and pharmacokinetics of lansoprazole (L15), omeprazole (O10, O20) and pantoprazole (P40) in Caucasians.

METHODS

CYP2C19 genotyping for *2–*6 and *17 mutations was assessed in subjects who were H. pylori negative in two randomized crossover trials. The influence of CYP2C19 mutations on single and repeated administration of L15 and O10 (study A) and O20 and P40 (study B) was investigated. Pharmacokinetics and the cumulative percentage of time with intragastric pH above 4 (% > pH 4) were assessed on day 1 and 6.

RESULTS

For study A CYP2C19 genotyping found five *1/*1, four *1/*2, one *1/*17 and one *2/*17. For study B the results were six *1/*1, two *1/*2, six *1/*17, one *2/*2 and one *2/*17. For all PPIs AUC was highest in *2/*2 and lowest in *1/*17. On day 1, all PPIs significantly increased percentage >pH 4 compared with baseline. *1/*1 genotype showed no significant acid-inhibition after L15, O10 and O20. *1/*17 genotype showed no significant acid-inhibition after O20 and P40. *1/*2 genotype showed significant acid-inhibition after L15 and O10. On day 6, all four PPIs showed significantly increased acid-inhibition. *1/*1 and *1/*17 showed a significantly increased percentage > pH 4 after treatment with O20 and P40. However, in *1/*1 subjects percentage > pH 4 was not significantly increased after L15 and O10. *1/*2 genotype showed a significant acid-inhibitory effect after repeated dosing with L15 and O10.

CONCLUSIONS

Caucasian subjects with *1/*1 and *1/*17 genotype need stronger acid-suppression therapy, especially during the first days of treatment or with on-demand therapy.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• The influence of CYP2C19 on the kinetics and dynamics of omeprazole, lansoprazole and rabeprazole has been studied in Japanese subjects.
• It has been suggested that subjects with *1/*1 genotype might need stronger acid suppression than *1/*2 and *2/*2 subjects. This suggestion comes from data in Japanese subjects and has not been confirmed in Caucasians.
• Furthermore, a novel CYP2C19 mutation, *17, which mainly occurs in Caucasians has been discovered. This mutation has been associated with clinical failure, but its relevance for therapy with PPIs has not been studied yet.

WHAT THIS STUDY ADDS

• In this study, the influence of CYP2C19 on both the pharmacokinetics and dynamics in Caucasian subjects after single and repeated dosing has been investigated.
• This is the first study showing that Caucasian subjects with *1/*1 and *1/*17 mutations need stronger acid-inhibition. In this study three proton pump inhibitors (omeprazole, lansoprazole and pantoprazole, in different doses) were studied of which pantoprazole had not been studied before in this setting, not even in Japanese.

     

Possible inhibitory effect of diazepam on the metabolism of zotepine,an antipsychotic drug

Effects of smoking and cytochrome P450 2C19 (CYP2C19) status on the single dose kinetics of zotepine and pharmacokinetic interaction between zotepine and diazepam were investigated. In 14 healthy volunteers, the pharmacokinetics of zotepine after a single oral 25 mg dose were compared between eight smokers and six non-smokers, or between seven extensive metabolizers (EMs) and seven poor metabolizers (PMs) of S-mephenytoin. There was no significant difference in any pharmacokinetic parameters between smokers and non-smokers, or between the EM and PM groups. In 17 patients treated with zotepine 80–340 mg/day, intra-individual changes in plasma concentrations of zotepine caused by coadministration of diazepam 10 mg/day for 2 weeks were examined. Plasma concentrations of zotepine were significantly increased after coadministration of diazepam (P < 0.05). Consequently, it is suggested that neither smoking nor CYP2C19 status affects the metabolism of zotepine. The elevation in plasma concentrations of zotepine after coadministration of diazepam may be a result of competitive inhibition of zotepine metabolism by diazepam via other isoenzyme than CYP2C19, e.g., CYP3A4. Received: 25 March 1996/Final version: 28 May 1996