CYP2D6 ultrarapid metabolism and morphine/codeine ratios in blood: was it codeine or heroin?

The concentration ratio of morphine (Mor) over codeine (Cod) in opiate positive blood samples is used to discriminate between the use of illegal heroin (high ratios) and therapeutic codeine (low ratios). However, genetically caused CYP2D6 ultra-rapid metabolism might lead to Mor/Cod comparable to heroin intake. A single oral dose of 30 mg codeine was administered to 11 CYP2D6 ultrarapid metabolizers (UMs) and 12 extensive metabolizers (EMs). Codeine and its morphine metabolites and Mor/Cod were quantified in plasma and urine by liquid chromatography with tandem mass spectrometry within 24 h after codeine intake. The Mor/Cod in plasma were below 1 for both UMs and EMs during the first 12 h. After 12 h, 9% of the 11 UM and none of the 12 EM had ratios > 1. In urine, Mor/Cod ratios were below one for all EMs and UMs during the first 12 h. Thus, CYP2D6 genotyping in general will not explain Mor/Cod ratios > 1 in plasma or urine, unless the time of drug intake is more than 24 h previous.     

CYP2D6基因多态性及其临床意义

CYP2D6是CYP酶系中重要的一种氧化代谢酶,参与多种药物的代谢.CYP2D6具有基因多态性,使药物代谢在不同种族之间,甚至在同种族不同人群中产生较大的差异,从而影响药物的疗效.因此,深入了解CYP2D6基因的多态性以及对药物代谢的影响,对指导临床合理用药和调整用药方案具有重大意义.     

CYP2D6基因与药物代谢

细胞色素P 45 0 (CYP)中的CYP2D6酶在抗抑郁药、安定药及某些抗心律失常药的代谢中起重要作用 ,CYP2D6基因位于 2 2号常染色体上为隐性遗传 ,CYP2D6基因呈多态性约有 70余种等位基因变异型 ,也存在特异人群差别 ,因而导致所编码的酶活性不同 ,这些数据有助于理解药物代谢的个体差异、有助于预测药物之间的相互作用。     

己烯雌酚对大鼠CYP2C6和CYP2D2酶的体外抑制作用

目的研究己烯雌酚对大鼠肝微粒体中细胞色素P450同工酶2C6(CYP2C6)和2D2(CYP2D2)的抑制作用。方法采用探针底物法,使用液相色谱-串联质谱检测在不同浓度的己烯雌酚孵育体系中,CYP2C6和CYP2D2的特征性底物双氯芬酸与右美沙芬产生的代谢产物4’-羟基双氯芬酸与右啡烷的浓度。计算得到己烯雌酚对CYP2C6与CYP2D2的半数抑制浓度(IC50)。结果己烯雌酚对大鼠CYP2C6与CYP2D2的IC50值分别为(5.31±0.06)μmol/L,(7.03±0.01)μmol/L。结论己烯雌酚对大鼠CYP2C6与CYP2D2具有中等抑制作用,有必要进一步在体外人体水平对其进行评价以预防潜在的临床药物相互作用。     

Inhibitory effects of phytochemicals on metabolic capabilities of.CYP2D6＊1 and CYP2D6＊10 using cell-based models in vitro

Aim： Herbal products have been widely used, and the safety of herb-drug interactions has aroused intensive concerns. This study aimed to investigate the effects of phytochemicals on the catalytic activities of human CYP2D6＊1 and CYP2D6＊10 in vitro. Methods： HepG2 cells were stably transfected with CYP2D6＊1 and CYP2D6＊10 expression vectors. The metabolic kinetics of the enzymes was studied using HPLC and fluorimetry. Results： HepG2-CYP2D6＊1 and HepG2-CYP2D6＊10 cell lines were successfully constructed. Among the 63 phytochemicals screened 6 compounds, including coptisine sulfate, bilobalide, schizandrin B, iuteolin, schizandrin A and puerarin, at 100 pmol/L inhibited CYP2D6＊1- and CYP2D6＊10-mediated O-demethylation of a coumarin compound AMMC by more than 50%. Furthermore, the inhibition by these compounds was dose-dependent. Eadie-Hofstee plots demonstrated that these compounds competitively inhibited CYP2D6＊1 and CYP2D6＊10. However, their K1 values for CYP2D6＊I and CYP2D6＊IO were very close, suggesting that genotype- dependent herb-drug inhibition was similar between the two variants. Conclusion： Six phytochemicals inhibit CYP2D6＊1 and CYP2D6＊lO-mediated catalytic activities in a dose-dependent manner in vitro. Thus herbal products containing these phytochemicals may inhibit the in vivo metabolism of co-administered drugs whose primary route of elimination is CYP2D6.     

与CYPOR共表达CYP2D6~*1和CYP2D6~*10及其代谢活性比较

细胞色素P450 2D6(cytochrome P450 2D6,CYP2D6)是一种重要的氧化代谢酶,呈基因多态性,对药物的代谢呈现明显的个体差异和种族差异,CYP2D6*10在中国人群中的发生率高达51.3%。采用杆状病毒昆虫表达系统,采用与细胞色素氧化还原酶(cytochrome oxidoreductase,CYPOR)共表达的方式获得具有代谢活性的CYP2D6*1/CYP2D6*10,并初步研究其催化右美沙芬的代谢活性差异。构建重组质粒pFastBac-CYP2D6*1,pFastBac-CYP2D6*10和pFastBac-CYPOR,并分别转化DH10Bac菌株构建重组Bacmid-CYPOR,Bacmid-CYP2D6*1和Bacmid-CYP2D6*10,转染Sf9昆虫细胞,获得重组杆状病毒用于病毒扩增和感染Sf9昆虫细胞。通过测定混悬蛋白催化右美沙芬的速率来优化重组CYPOR和CYP2D6病毒感染Sf9昆虫细胞的感染复数(multiplicity of infection,MOI)值和其比例,获得活力较高的重组CYP2D6*1和CYP2D6*10。重组CYP2D6*1催化右美沙芬的Km为(...     

ASA法测定细胞色素P450 2D6酶缺陷等位基因CYP2D6E

目的 :建立细胞色素P4 50 2D6(CYP2D6)第 3 0 2 3位A→C突变造成CYP2D6酶活性缺陷的等位基因CYP2D6E的测定方法。方法 :利用等位基因特异扩增法 (ASA)为基本原理 ,设计两对引物分别扩增野生型等位基因和突变型等位基因。结果 :经 3 96例测定 ,发现 2例CYP2D6E与CYP2D6B的异突变型纯合子 ,其表现型均为慢代谢者。阳性对照说明本法重复性好 ,阴性对照显示本法无污染问题。结论 :本法比PCR -RFLP法更为快捷、更少污染。对CYP2D6E的测定有助于准确预测CYP2D6表现型     

细胞色素P450 2D6等位基因CYP2D6C的特异扩增法测定

细胞色素Ｐ４５０２Ｄ６（ＣＹＰ２Ｄ６）第２７０３－５位ＡＡＧ缺失造成表达产物第２８１位赖氨酸缺失的等位基因称为ＣＹＰ２Ｄ６Ｃ．利用等位基因特异扩增法（ＡＳＡ）原理,建立了ＡＳＡ－ＰＣＲ测定ＣＹＰ２Ｄ６的方法．经３９６例测定,说明本法快捷,污染少．测定结果显示ＣＹＰ２Ｄ６Ｃ不属于ＣＹＰ２Ｄ６酶缺陷等位基因,表型仍为快代谢．     

Metabolism of (−)-fenchone by CYP2A6 and CYP2B6 in human liver microsomes

The in vitro metabolism of (?)-fenchone was examined in human liver microsomes and recombinant enzymes. The biotransformation of (?)-fenchone was investigated by gas chromatography-mass spectrometry. (?)-Fenchone was found to be oxidized to 6-exo-hydroxyfenchone, 6-endo-hydroxyfenchone and 10-hydroxyfenchone by human liver microsomal P450 enzymes. The formation of metabolites was determined by the relative abundance of mass fragments and retention times on gas chromatography (GC). CYP2A6 and CYP2B6 were major enzymes involved in the hydroxylation of (?)-fenchone by human liver microsomes, based on the following lines of evidence. First, of 11 recombinant human P450 enzymes tested, CYP2A6 and CYP2B6 catalysed the oxidation of (?)-fenchone. Second, oxidation of (?)-fenchone was inhibited by thioTEPA and (+)-menthofuran. Finally, there was a good correlation between CYP2A6, CYP2B6 contents and (?)-fenchone hydroxylation activities in liver microsomes of 11 human samples. CYP2A6 may be more important than CYP2B6 in human liver microsomes. Kinetic analysis showed that the V_max/K_m values for (?)-fenchone 6-endo-, 6-exo- and 10-hydroxylation catalysed by liver microsomes of human sample HG-03 were 24.3, 44.0 and 1.3?nM^?1?min^?1, respectively. Human recombinant CYP2A6 and CYP2B6 catalysed (?)-fenchone 6-exo-hydroxylation with V_max values of 2.7 and 12.9?nmol?min^?1?nmol^?1 P450 and apparent K_m values of 0.18 and 0.15?mM and (?)-fenchone 6-endo-hydroxylation with V_max values of 1.26 and 5.33?nmol?min^?1?nmol^?1 P450 with apparent K_m values of 0.29 and 0.26?mM. (?)-Fenchone 10-hydroxylation was catalysed by CYP2B6 with K_m and V_max values of 0.2?mM and 10.66?nmol?min^?1?nmol^?1 P450, respectively.     

Differential outcomes from metabolic ratios in the identification of CYP2D6 phenotypes–focus on venlafaxine and O-desmethylvenlafaxine

Background  

Venlafaxine (VEN), a well accepted anti-depressant, is metabolized through the cytochrome P 450 (CYP) 2D6 isozyme to form O-desmethyvenlafaxine (ODV). Due to the involvement of CYP2D6, the formation of ODV is influenced by genetic polymorphism. We used standard tools of assessment to explore the phenotypic distribution in a retrospective manner using the pharmacokinetic (PK) data of VEN and ODV obtained from several bioavailability/bioequivalence (BA/BE) studies in healthy subjects using the reference formulation.     

ASA法测定细胞色素P4502D6酶缺陷等位基因CYP2D6E

目的：建立细胞色素Ｐ４５０ ２Ｄ６（ＣＹＰ２Ｄ６）第３０２３位Ａ→Ｃ突变成ＣＹＰ２Ｄ６酶活性缺陷的等位基因ＣＹＰ２Ｄ６Ｅ的测定方法。方法：利用等位基因特异扩增法（ＡＳＡ）为基本原理,设计两对引物分别扩增野生型等位基因和突变型等位基因。结果：经３９６例测定,发现２例ＣＹＰ２Ｄ６Ｅ与ＣＹＰ２Ｄ６Ｂ的异突变型纯合子,其表现型均为慢代谢者。     

CYP2 D6的基因多态性与药物临床应用

CYP2D6是CYP酶系中重要的一种氧化代谢酶,参与多种药物的代谢。 CYP2D6具有基因多态性,这是构成药物代谢个体差异和种族差异的基础,它主要参与心血管类、抗精神病类、镇痛药、以及一些抗癌药物等的代谢。研究 CYP2D6基因多态性与药物代谢个体差异的相关性,有助于减轻药物不良反应,提高治疗效果,实施个体化给药。     

氧化苦参碱对大鼠CYP2D6酶的影响

目的 通过氧化苦参碱的大鼠体内、外实验,观察氧化苦参碱对大鼠CYP2D6 亚型酶的影响.方法 HPLC法测定大鼠尿液及肝微粒体中探针药物右美沙芬(DM)、代谢物去甲右美沙芬(DT)的含量.对照组和氧化苦参碱组大鼠分别经口给予生理盐水和氧化苦参碱两周,HPLC法测定大鼠尿样及肝微粒体中CYP2D6的探针药物右美沙芬的代谢率,观察氧化苦参碱对CYP2D6活性的影响.并且通过特异性抑制剂确定在肝微粒体重组系统中氧化苦参碱对CYP2D6亚型的影响.结果 实验组大鼠给予氧化苦参碱(100mg/kg),其尿样中右美沙芬的代谢率与对照组相比没有明显差别(P>0.05);实验组大鼠肝微粒体中加入右美沙芬(0.324mmol/L),其右美沙芬的代谢率与对照组相比没有明显差别(P>0.05);氧化苦参碱没有明显降低右美沙芬的代谢率(P>0.05),而CYP2D6特异性抑制剂西米替丁却明显降低右美沙芬的代谢率(P<0.01).结论 氧化苦参碱对CYP2D6酶无明显影响.     

丹参注射液对家兔体内CYP1A2、CYP2D6和CYP3A4活性的影响

目的：用Cocktail探针药物法研究丹参注射液对家兔细胞色素P450亚型酶活性的影响。方法：将家兔随机分成四组,耳缘静脉注射给予丹参注射液,分低、中、高剂量三个实验组,空白对照组给予生理盐水。用HPLC法测定各组Cock-tail探针药物（咖啡因、美托洛尔和氨苯砜）的血药浓度,比较药时曲线及药代动力学参数的变化,评价各组细胞色素P450亚型酶的活性。结果：丹参注射液低、中、高剂量组CYP2D6的活性与对照组相比降低,具有统计学意义（P〈0.05或P〈0.01）;CYP1A2和CYP3A4的活性与对照组相比差异均无统计学意义。结论：丹参注射液对家兔CYP2D6有抑制作用,对CYP1A2和CYP3A4的影响不显著。提示临床应用丹参注射液时,应关注其对CYP2D6的抑制作用,避免联合用药引发CYP2D6介导的药物相互作用,促进临床安全合理用药。     

CYP1A2、CYP2D6和CYP2C19基因多态性与氯氮平及其代谢物血药浓度的相关性研究

目的：研究CYP1A2、CYP2D6和CYP2C19基因多态性与精神分裂症患者氯氮平（clozapine,CLZ）及其活性代谢物去甲氯氮平（N-desmethy clozapine,N-CLZ）血药浓度的相关性。方法：纳入156例经CLZ单药治疗1个月以上的精神分裂症患者,采集清晨服药前空腹血,采用液相色谱-串联质谱（LC-MS/MS）法测定CLZ及N-CLZ稳态谷浓度。通过Axiom基因芯片分析技术检测CYP1A2（*1C、*1F）、CYP2D6（*2、*10）、CYP2C19（*2、*3）等6个SNP位点的基因型,比较不同基因型患者CLZ及其代谢物的浓度剂量比（C/D）及代谢物与CLZ血药浓度比值（C_N-CLZ/C_CLZ）的差异。结果：CYP2D6*10基因多态性与N-CLZ C/D具有相关性（P<0.01）。CYP1A2*1C、CYP2D6（*2、*10）基因多态性与C_N-CLZ/C_CLZ具有相关性（P<0.05,P<0.01,P<0.01）。CYP1A2*1F、CYP2C19*2、CYP2C19*3基因多态性与C/D及C_N-CLZ/C_CLZ无相关性（P>0.05）。结论：CYP1A2*1C和CYP2D6（*2、*10）基因多态性对CLZ代谢存在影响,建议临床在使用CLZ治疗前检测患者CYP1A2*1C和CYP2D6（*2、*10）基因型,为CLZ个体化治疗提供参考。