非甾体抗炎药药物代谢酶多态性的研究进展

非甾体抗炎药(NAIDs)是一类具有解热、镇痛和抗炎作用的药物,临床上用于治疗骨关节炎、类风湿关节炎等疾病,疗效确切但常伴有胃肠道不适等不良反应,其产生与其药物代谢酶的遗传多态性有关.参与NSAIDs氧化代谢的细胞色素P450酶系,主要有CYP2C9、CYP1A2、CYP2E1和CYP3A4,本文就NSAIDs的药物代谢酶及其多态性和P450代谢的部分NSAIDs(双氯芬酸、布洛芬、氟比洛芬、萘普生和醋氨芬)等作一综述.     

木犀草素(苷)与药物代谢酶相互作用的研究进展

综述木犀草素及其苷的各相代谢研究及其与药物代谢酶的相互作用。木犀草素的代谢主要受二相代谢酶介导，其苷首先在肠道被水解成苷元，再被吸收，代谢。木犀草素对一相代谢酶CYP3A有诱导作用，而对CYP1A，1B和2E有强抑制作用，此外木犀草素也是CYP2B6，CYP2C9和CYP2D6有效的抑制剂；木犀草素对二相代谢酶SULTs有强抑制作用；并对多种ABC转运蛋白有抑制作用。了解木犀草素及其苷与药物代谢酶的相互作用，对其临床安全合理用药具有重要指导意义。     

Measurement of hepatic drug-metabolizing enzyme activity in man

Summary Three parameters of hepatic drug metabolism, cytochrome P-450 (P-450) content, antipyrine metabolism and urinary excretion of glucaric acid (GA) were investigated in 161 patients who underwent diagnostic liver needle biopsy. P-450 and antipyrine metabolism, but not GA were related to histological changes in liver. All the parameters were significantly increased in subjects treated with enzyme-inducing drugs, the extent of induction being related to alterations in liver histology. The largest responses were seen in subjects with an intact liver and the smallest in those with hepatitis or cirrhosis. Therapy with inducers partly compensated for the impairement in drug metabolism caused by the disease process; thus, some patients with altered liver had normal values in the tests if they had been treated with inducers. There were significant correlations between in vivo and in vitro parameters of drug metabolism, but in the interpretation of data selection of the material and the parameters influenced the results. Thus, the antipyrine plasma clearance rate was directly related to P-450 and GA values, whereas the correlation between the latter and the drug half-life was non-linear. Also, comparison of selected groups of patients resulted in better correlations between the indices of drug metabolism than in the entire series. The results demonstrate that the overall picture of hepatic drug metabolism in man is largely determined by histological changes in the liver and by exposure to drugs, which are reflected differently in various assays of hepatic drug metabolism. Quantitative evaluation of these factors, and selection of the appropriate assay method, seem to be of importance in investigating hepatic drug metabolism in man.     

细胞色素P450酶基因多态性的研究进展及临床意义

细胞色素P450（cytochrome P450,CYP）是重要的药物代谢酶,参与催化多种内源和外源化合物,特别是多种临床药物的生物转化。CYP存在广泛的基因多态性和表型多态性,体现在个体对于各种化合物的代谢存在明显差异。本文综述了CYP的基因多态性、与药物代谢相关的CYP各亚型的特点和临床意义,主要目的是合理解释和预测临床上药物间相互作用和药物不良反应等,为实现临床个体化给药提供科学依据。     

CYP450氧化还原酶的遗传多态对药物代谢的影响

CYP450氧化还原酶(cytochrome P450 oxidoreductase,POR)是所有肝微粒体的细胞色素P450氧化酶(cytochrome P450 monooxygenases,CYP)的唯一电子供体,其中一些CYP是I相药物代谢酶,负责临床上超过80%药物的氧化代谢。另外,POR直接介导了一些抗肿瘤前体药物的代谢。因此,POR的遗传多态引起其活性的改变,对临床药物代谢具有非常重要的临床意义。该文总结了近年来POR的遗传多态影响药物代谢的最新研究进展。     

六种大鼠肝微粒体细胞色素P450重组酶系对33种外来化合物的代谢

多氯联苯诱导的六种鼠肝微粒体细胞色素P450重组酶系A_1,A_2,B,C_1,C_2和D对33种外来化合物代谢的催化速率不同,其中以C_1酶系和C_2酶系催化活力最强,其次为A_1酶系,B酶系催化活力最弱,外来化合物的种类不同,经重组酶系催化的途径也不同,如卤代烷烃,卤代烯烃,苯及其同系物,亚硝胺类等化合物主要经P450C_1酶系代谢,而大多数有机磷酸酯,氨基甲酸酯类化合物及多环芳烃类致癌物则以P450 C_2酶系代谢为主。     

细胞色素P450 2D6氧化酶研究的表型分析及探针药物

近年来细胞色素P450酶（CYP450）的多态性已成为研究热点,而作为研究手段的表型分析及探针药物直接关系到研究的价值和意义.现综述CYP450 2D6氧化酶多态性研究的表型分析的影响因素及优缺点,并介绍几种探针药物,包括右美沙芬、美托洛尔、普罗帕酮、可待因、异喹胍、司巴丁的特点及其检测方法.     

Effects of silver nanoparticles on rat hepatic cytochrome P450 enzyme activity

Silver nanoparticles (AgNPs) are increasingly used in various products and consequentially the potential adverse effects associated with exposure to them are of concern. This study investigated the effects of AgNPs on the hepatic drug-metabolizing enzymes of the cytochrome P450 (CYP) families 1, 2 and 3, using both in vitro and in vivo biological assays. AgNPs were orally administered to Sprague-Dawley rats at various concentrations (0–1000?mg/kg body weight/day) for 2 weeks. No effect was found on the plasma levels of ALT, AST and ALP in all treated rat groups, and no significant change in the activities of CYP1A, CYP2C, CYP2D, CYP2E1 and CYP3A was observed for all tested AgNP doses. The results correlated with the observation that no AgNPs were detected in the liver sections of the tested rats. However, the in vitro system using rat liver microsomes demonstrated a strong inhibition of CYP2C (IC₅₀?=?28 µg/mL) and CYP2D (IC₅₀?=?23 µg/mL) activities, but not of CYP1A, CYP2E1 and CYP3A activities (IC₅₀ > 100 µg/mL) at concentrations up to 100 µg/mL of AgNPs. The inhibitory effect of AgNPs on these CYPs indicates the possibility of the AgNP-drug interaction when co-administered with some medicines and this may cause adverse effects to patients.     

细胞色素P450的基因多态性与药物代谢

细胞色素P450（cytochrome P450，CYP）是重要的药物代谢酶，参与催化多种内源和外源化合物，特别是多种临床药物的生物转化。CYP存在广泛的基因多态性和表型多态性，使其对于各种化合物的代谢存在统计学个体差异。核受体是配体依赖性转录因子超家族，与药物代谢过程中的基因表达调控密切相关，被外源物质活化后诱导或抑制CYP基因的表达。现综述CYP与药物代谢、CYP的基因多态性、CYP表达的诱导机制、核受体及其配体诱导CYP表达及近年研究CYP450的各种实验方法。     

The paraoxonase-1 pathway is not a major bioactivation pathway of clopidogrel in vitro

BACKGROUND AND PURPOSE

Clopidogrel is a prodrug bioactivated by cytochrome P450s (CYPs). More recently, paraoxonase-1 (PON1) has been proposed as a major contributor to clopidogrel metabolism. The purpose of this study was to assess the relative contribution of CYPs and PON1 to clopidogrel metabolism in vitro.

EXPERIMENTAL APPROACH

Clopidogrel metabolism was studied in human serum, recombinant PON1 enzyme (rePON1), pooled human liver microsomes (HLMs), HLMs with the CYP2C19*1/*1 genotype and HLMs with the CYP2C19*2/*2 genotype. Inhibition studies were also performed using specific CYP inhibitors and antibodies. Clopidogrel and its metabolites were measured using LC/MS/MS method.

KEY RESULTS

PON1 activity was highest in the human serum and there was no difference in PON1 activity between any of the HLM groups. The production of clopidogrel''s active metabolite (clopidogrel-AM) from 2-oxo-clopidogrel in pooled HLMs was approximately 500 times that in serum. When 2-oxo-clopidogrel was incubated with rePON1, clopidogrel-AM was not detected. Clopidogrel-AM production from 2-oxo-clopidogrel was lower in CYP2C19*2/*2 HLMs compared with CYP2C19*1/*1 HLMs, while PON1 activity in HLMs with both genotypes was similar. Moreover, incubation with inhibitors of CYP3A, CYP2B6 and CYP2C19 significantly reduced clopidogrel bioactivation while a PON1 inhibitor, EDTA, had only a weak inhibitory effect.

CONCLUSION AND IMPLICATIONS

This in vitro study shows that the contribution of PON1 to clopidogrel metabolism is limited at clinically relevant concentrations. Moreover, CYP2C19, CYP2B6 and CYP3A play important roles in the bioactivation of clopidogrel.     

咖啡因试验与氯氮平体内代谢的相关性

通过检测尿中咖啡因（Ｃａｆ）及其代谢产物,探讨细胞色素Ｐ４５０ １Ａ２（ＣＹＰ１Ａ２）与体内氯氮平（ＣＬＺ）去甲基代谢物的关系。方法单剂ｐｏ Ｃａｆ１５０ｍｇ,ｈ５末采取尿样,以Ｃａｆ代谢产物和Ｃａｆ的比值「（１７Ｘ＋１７Ｕ）／１３７Ｘ」反映ＣＹＰ１Ａ２活性。２ｄ后单剂ｐｏＣＬＺ１０ｍｇ,收集０－２４ｈ尿样。０－２４ｈ悄中ＣＬＺ剩余量占给药剂量的分率（ＣＬＺ％）反映ＣＬＺ清除;０－２４ｈ尿中去甲     

Relevance of induction of human drug-metabolizing enzymes: pharmacological and toxicological implications

1 Human drug-metabolizing systems can be induced, or activated, by a large number of exogenous agents including drugs, alcohol, components in the diet and cigarette smoke, as well as by endogenous factors.
2 Such perturbation of enzyme activity undoubtedly contributes to both intra- and inter-individual variation both with respect to the rate and route of metabolism for a particular drug. Induction may, in theory, either attenuate the pharmacological response or exacerbate the toxicity of a particular drug, or both.
3 The clinical impact of enzyme induction will depend upon the number of different enzyme isoforms affected and the magnitude of the inductive response within an individual, and also on the therapeutic indices of the affected substrates.
4 The toxicological implications will be determined either by any change in the route of metabolism, or by a disturbance of the balance between activation and detoxication processes, which may be isozyme selective.     

Drug-metabolizing activity of human and rat liver,lung, kidney and intestine slices

1. Organ-specific biotransformation was studied in human and rat liver, lung, kidney and small intestine slices and compared on a protein basis, using four model substances. 2. Deethylation of lidocaine was highest in liver slices from both man and rat, followed by the small intestine. 3. Metabolism of testosterone was highest in liver slices, but a different overall metabolic pattern was found between the different organs. 4. Lung, kidney and intestine slices prepared from human and rat organs showed mainly an unknown metabolite of 7-ethoxycoumarin identified as 4-ethoxy-2-hydroxyphenyl propionic acid (EPPA). 5. The maximal metabolism of 7-ethoxycoumarin in slices was equal with in vivo V_max in the rat. 6. Phase II metabolism of 7-hydroxycoumarin in kidney and intestinal slices was about 60% of the activity in liver slices. 7. In conclusion, organs other than the liver show a surprisingly high drug-metabolizing activity. Thus, the use of precision-cut slices of a combination of drug metabolizing organs in an in vitro test system from both animal and human origin is required for a proper systematic prediction of drug metabolism in man.     

Phenotypic polymorphism and gender-related differences of CYP1A2 activity in a Chinese population

AIMS: To investigate the distribution characteristics of CYP1A2 in a Chinese population, and to examine gender-related differences in CYP1A2 activity. METHODS: Two hundred and twenty-nine healthy subjects, 120 men and 109 women, were enrolled in this study. CYP1A2 activity was measured by plasma paraxanthine/caffeine (1,7X/1,3,7X) ratio 6 h after administration of 300 mg caffeine. The concentrations of paraxanthine and caffeine in plasma were detected by h.p.l.c. RESULTS: A 16-fold variation of CYP1A2 activity (range 0. 09 to 1.46) was shown in this study. The coefficient of variation (CV %) of CYP1A2 activity was 62.9%. Non-normal distribution of CYP1A2 activity was indicated by the Shapiro-Wilk test (P<0.001). Probit plots of CYP1A2 activity revealed a bimodal distribution with breakpoint of 1,7X/1,3,7X ratio of 0.12. The percentage of poor metabolizers (PMs) was 5.24% (95% CI: 2.35% approximately 8.13%) in this Chinese population. Residual analysis of the data also supported bimodality (P<0.01). The CYP1A2 activity of men was higher than that of women (median: 0.33 vs 0.23, P<0.001). A probit plot of CYP1A2 activity in men was shifted to the left compared with that in women. Based on phenotype, the gender-related difference was observed in extensive metabolizers (EMs) (P<0.001), but not in PMs (P >0.1). In addition, there was no sex-related difference in the incidence of PMs (P >0.1). CONCLUSIONS: There is a phenotypic polymorphism in CYP1A2 activity in this Chinese population, and CYP1A2 activity is higher in men than that in women.     

Population pharmacokinetic modelling of aripiprazole and its active metabolite,dehydroaripiprazole, in psychiatric patients

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Almost all reported studies have investigated the pharmacokinetics of aripiprazole in healthy volunteers.
• The pharmacokinetics of dehydroaripiprazole have not been identified in a combined model with aripiprazole.

WHAT THIS STUDY ADDS

• The data on aripiprazole and dehydroaripiprazole in psychiatric patients were modelled jointly using a population approach.
• The apparent clearance of aripiprazole in cytochrome P450 (CYP) 2D6 intermediate metabolizers (IM) was approximately 60% of that in CYP2D6 extensive metabolizers (EM) having two functional alleles, but the exposure to dehydroaripiprazole in CYP2D6 IM was similar to that in EM.

AIMS

The aims of this study were to develop a combined population pharmacokinetic model for both aripiprazole and its active metabolite, dehydroaripiprazole, in psychiatric patients and to identify to what extent the genetic polymorphisms of cytochrome P450 (CYP) enzymes contribute to the variability in pharmacokinetics (PK).

METHODS

A population pharmacokinetic analysis was performed using NONMEM software based on 141 plasma concentrations at steady state from 80 patients receiving multiple oral doses of aripiprazole (10–30 mg day¹).

RESULTS

A one-compartment model with first-order kinetics for aripiprazole and dehydroaripiprazole each was developed to describe simultaneously the concentration data. The absorption rate constant was fixed to 1.06 h¹. The typical value of apparent distribution volume of aripiprazole was estimated to be 192 l. Covariate analysis showed that CYP2D6 genetic polymorphisms significantly influenced the apparent clearance of aripiprazole (CL/F), reducing the interindividual variability on CL/F from 37.8% CV (coefficient of variation) to 30.5%. The CL/F in the CYP2D6 IMs was approximately 60% of that in CYP2D6 EMs having two functional alleles. Based on the CYP2D6 genotype, the metabolic ratios were calculated at 0.20–0.34. However, the plasma concentration : dose ratios of dehydroaripiprazole were not different across the CYP2D6 genotype.

CONCLUSIONS

This population pharmacokinetic model provided an adequate fit to the data for both aripiprazole and dehydroaripiprazole in psychiatric patients. The usefulness of CYP genotyping as an aid to select the starting dose should be further investigated.     

药物代谢酶遗传多态性对药物神经毒性的影响

神经毒性是药物常见的毒性反应之一。神经系统对药物引起的损害尤其敏感,药物引起神经系统结构和功能的微小改变即可表现出严重的精神或行为异常,因此药物引起的神经毒性越来越得到人们的关注。药物引起的神经毒性存在个体差异,其中遗传因素对这种差异的产生发挥重要作用。药物代谢酶影响药物体内的生物转化过程,因此代谢酶的遗传多态性在一定程度上决定了不同个体对药物神经毒性的易感性。本篇综述将着重探讨药物代谢酶中的细胞色素P450酶、谷胱甘肽转移酶和N-乙酰转移酶遗传多态性对药物神经毒性易感性的影响。     

Cytochrome P450 enzyme activity and protein expression in primary porcine enterocyte and hepatocyte cultures

1. A method for the isolation and cultivation of porcine hepatocytes and porcine duodenal enterocytes for the investigation of drug oxidation reactions has been established. 2. Hepatocytes as well as enterocytes metabolized ethoxyresorufin (EROD) and ethoxycoumarin (ECOD) effectively, the rate being 31 +/- 17 pmol/h dish (EROD) and 9530 +/- 4062 pmol/h dish (ECOD) in the case of hepatocytes, and 9 +/- 4 pmol/h dish (EROD) and 510 +/- 467 pmol/h dish (ECOD) in the case of enterocytes. Diazepam, another CYP monooxygenase substrate, was also metabolized by porcine hepatocytes but not with porcine enterocytes, thus indicating differences in the metabolic competence of the liver and the gut. 3. The ability to induce enzymes responsible for the metabolism of ethoxyresorufin and ethoxycoumarin was investigated in vitro on treatment of the cell cultures with either 50 muM 3-methylcholanthrene (3-MC) or 50 muM beta-naphthoflavone (beta-NF). With enterocyte cultures, ECOD activity was inducible up to 20-fold, whereas EROD remained unchanged following treatment with either 3-MC or beta-NF. 4. Western blotting provided additional evidence for the expression of CYP1A1 and CYP3A4 at the protein level and treatment of cultured enterocytes with 30 muM Aroclor 1254 or 50 muM beta-NF resulted in enhanced expression of the CYP1A protein, and CYP3A4 protein expression was induced following treatment with 50 muM DEX, 2 mM PB, 30 muM Aroclor 1254 or 50 muM beta-NF. 5. The metabolism of diazepam was also investigated with baculovirus-expressed human CYP enzymes (2C8, 2C9-ARG, 2C9-CYS, 2C19, 3A4, 3A4+cytochrome b₅ and 3A5) and evidence was obtained to suggest the formation of temazepam and oxazepam by enzymes of the CYP3A subfamily. Small amounts (32 +/- 12 ng/ml) of desmethyldiazepam were additionally recovered in microsomal preparations of all CYP-transfected cell lines. 6. In conclusion, porcine duodenal enterocytes can successfully be cultured for a short period and may be used as a tool for studying intestinal metabolism, whereas porcine hepatocytes can be cultured for prolonged periods (&gt; 10 days) reliably to investigate hepatic drug oxidation reactions.     

细胞色素氧化酶CYP 1A2基因多态性与物质代谢和癌症发生相关性的研究进展

细胞色素氧化酶CYP 1A2亚家族是近年来药物代谢研究领域较受关注的热点之一。该酶具有高度的个体间差异,并参与多种临床药物以及环境致癌物质的代谢,与癌症、炎症、心肌梗塞等疾病的发病易感性相关。CYP 1A2具有抗氧化作用;CYP 1A2基因多态性和表型差异的研究,可用于评价临床药物治疗效果;探针药物的应用是研究CYP 1A2活性的主要方法;人源化CYP 1A2转基因动物模型,是癌症发生研究中、新的研究手段。     

用体外代谢数据预测临床上药物体内代谢性相互作用

用体外代谢数据可以预测临床上药物体内代谢的相互作用。本文介绍其中一些重要概念、预测模型、方法及影响预测准确性的因素。