Polymorphisms in the VKORC1 gene are strongly associated with warfarin dosage requirements in patients receiving anticoagulation

Background

Warfarin is a mainstay of therapy for conditions associated with an increased risk of thromboembolic events. However, the use of this common agent is fraught with complications and little is known regarding inter‐individual variation in warfarin response.

Objective

We tested for association between single nucleotide polymorphisms (SNPs) in VKORC1 and CYP2C9 and average weekly warfarin dose required to maintain patients at their desired anticoagulation target.

Methods

The sample consisted of 93 European‐American patients from anticoagulation clinics at the University of North Carolina at Chapel Hill. Data on mean weekly warfarin dose were collected over a mean treatment period of 20.6 months. ANCOVA models were used and haplotype analysis was performed.

Results

Three of six VKORC1 SNPs were found to be very strongly associated with the average warfarin dose required to achieve the target international normalised ratio (INR; p<0.0001). The mean weekly dose by genotype ranged from approximately 27 to 47 mg. There was no evidence for an association between either of the two CYP2C9 polymorphisms studied, CYP2C9*2 and CYP2C9*3. CYP2C9*3 was significantly (p = 0.05) associated with average warfarin dosage after adjustment for VKORC1*1173.

Conclusions

These results are of considerable clinical interest and confirm recently published results regarding the role of these two genes in modifying warfarin metabolism and maintenance dosage. The consistent findings regarding the role of VKORC1 and CYP2C9 in warfarin metabolism and maintenance dosage represent a clinically useful proof of principal for the use of pharmacogenomic information in medicine and may lead to improved understanding of warfarin''s actions.     

苔黑酚葡萄糖苷对L02细胞肝药酶CYP3A的调控作用研究

目的观察苔黑酚葡萄糖苷对体外培养的正常肝细胞株L02中CYP3A的影响,探讨苔黑酚葡萄糖苷是否通过cAMP-PKA信号通路调控CYP3A的活性。方法分别用cAMP-PKA信号通路中蛋白激酶A(PKA)激动剂环腺苷酸(cAMP)类似物8-溴-环腺苷酸(8-Br-cAMP)及其抑制剂H-89、苔黑酚葡萄糖苷干预L02细胞,MTT法检测细胞活力,完整细胞免疫组化法检测PKA蛋白表达,红霉素-N-脱甲基法检测CYP3A活性,Western blotting检测细胞中孕烷X受体(PXR)蛋白表达。结果与对照组(加入不含药的无血清培养基)相比,苔黑酚葡萄糖苷处理后的细胞CYP3A的活性增强,PKA、PXR蛋白表达增强,与8-Br-cAMP的作用相似。结论苔黑酚葡萄糖苷可通过cAMP-PKA信号通路调控CYP3A的表达,表明其可能是仙茅表现出辛热药性的主要成分之一。     

Herbal medicines for the prevention of alcoholic liver disease: A review

Ethnopharmacological relevance

Long-term excess alcohol exposure leads to alcoholic liver disease (ALD)—a global health problem without effective therapeutic approach. ALD is increasingly considered as a complex and multifaceted pathological process, involving oxidative stress, inflammation and excessive fatty acid synthesis. Over the past decade, herbal medicines have attracted much attention as potential therapeutic agents in the prevention and treatment of ALD, due to their multiple targets and less toxic side effects. Several herbs, such as Cnidium monnieri (L.) Cusson (Apiaceae), Curcuma longa L. (Zingiberaceae) and Pueraria lobata (Willd.) Ohwi (Leguminosae), etc., have been shown to be quite effective and are being widely used in China today for the treatment of ALD when used alone or in combination.

Aim of the review

To review current available knowledge on herbal medicines used to prevent or treat ALD and their underlying mechanisms.

Materials and methods

We used the pre-set searching syntax and inclusion criteria to retrieve available published literature from PUBMED and Web of Science databases, all herbal medicines and their active compounds tested on ALD induced by both acute and chronic alcohol ingestion were included.

Results

A total of 40 experimental studies involving 34 herbal medicines and (or) active compounds were retrieved and reviewed. We found that all reported extracts and individual compounds from herbal medicines/natural plants could be beneficial to ALD, which might be attributed to regulate multiple critical targets involved in the pathways of oxidation, inflammation and lipid metabolism.

Conclusions

Screening chemical candidate from herbal medicine might be a promising approach to drug discovery for the prevention or treatment of ALD. However, further studies remain to be done on the systematic assessment of herbal medicines against ALD and the underlying mechanisms, as well as their quality control studies.     

苯妥英钠血药浓度与CYP2C19基因多态性关系的研究

目的:探讨苯妥英钠药物浓度与CYP2C19基因多态性的关系,以指导临床个体化用药.方法:运用血药浓度监测仪测定患者血药浓度和变性高效液相色谱法检测癫痫患者的CYP2C19基因多态性位点,对二者结果进行相关性分析.结果:21例中国汉族癫痫患者中有12例含突变型CYP2C19基因.在7例(58.33%)苯妥英钠血药浓度的比值高于剂量比值的患者中,6例(85.7%)为突变型基因携带者(慢代谢者).结论:CYP2C19是苯妥英钠的主要代谢酶.CYP2C19基因突变等位基因携带者苯妥英钠代谢减慢,应给予小剂量苯妥英钠,以减少药物不良反应的发生和药物资源的浪费.     

体内、体外相结合测定及评价CYP2C19 酶活性研究的方法建立

目的:建立一种快速、准确的以奥美拉唑(Omeprazole,OPZ)作为“探针药物”评价或测定细胞色素P450 2C19(CYP2C19)酶活性的高效液相色谱(HPLC)-紫外检测(VWD)方法.方法:采用的色谱柱为Agilent Extend-C18柱(4.6 mm×100 mm,5μm),流速1.0 mL·min-1,紫外检测波长290 nm,柱温40℃.体内实验:大鼠静脉注射OPZ(20 mg· kg-1),按时间点眼眶取血,检测OPZ与其代谢产物5’-羟基奥美拉唑(5’-hydroxy omeprazole,5 '-OHOPZ)的血浆药物浓度.体外实验:不同浓度OPZ与大鼠肝微粒体温孵后,检测温孵体系中5’-OHOPZ的浓度,以其生成的速率来评价CYP2C19酶的活性.结果:体内实验:内标非那西丁、OPZ与5’-OHOPZ保留时间(tR)分别为8.91,10.26,14.93 min,OPZ线性范围为0.28 ～18.0 mg·L-1,最低定量限(lower limit of quantitation,LLOQ)为0.28 mg·L-1,高、中、低浓度提取回收率分别为91.13％,97.21％,96.55％,OPZ的日内、日间相对标准偏差(relative standard deviation,RSD)小于10％;5’-OHOPZ线性范围为0.19 ～6.25 mg·L-1,LLOQ为0.19 mg·L-1,高、中、低浓度提取回收率分别为94.36％,97.57％,90.64％,5’-OHOPZ的日内、日间RSD小于10％.体外实验:内标非那西丁、OPZ与5’-OHOPZ的保留时间(tR)分别为8.91,10.26,14.93 min,5’-OHOPZ的线性范围为0.06 ～2.0 mg·L-1,LLOQ为0.06 mg·L-1,高、中、低浓度提取回收率分别为96.53％,99.40％,98.00％,日内、日间RSD差小于10％.结论:大鼠血浆及肝微粒体温孵体系中的其他内源性物质不干扰待测物的测定.该方法快速、稳定、灵敏度高,适合OPZ及其代谢产物5’-OHOPZ的测定,该文建立了体内、体外相结合测定及评价CYP2C19酶活性研究的方法.     

脑心通胶囊干预经皮冠状动脉介入术后抗栓治疗27例临床研究

目的 探讨脑心通胶囊干预经皮冠状动脉介入术(PCI)后抗栓治疗的疗效. 方法 选取行PCI成功且符合纳入标准的冠心病患者54例,随机分为治疗组和对照组各27例.对照组进行术后规范抗栓治疗,治疗组在对照组基础上加用脑心通胶囊,每次4粒,每天3次,连续使用1个月.观察治疗前、治疗后10天气虚证、血瘀证积分及远近期抗栓疗效,同时评估安全性. 结果 与治疗前比较,治疗组治疗后10天气虚证积分明显降低(P＜0.01),对照组明显升高(P＜0.01);两组患者治疗后10天血瘀证积分、最大血小板聚集率(MPA)、血浆遗传性假血友病因子(vWF)、血小板膜糖蛋白Ⅱb/Ⅲa(GPⅡb/Ⅲa)、凝血酶原片段1+2[F(1+2)]和纤维蛋白原(Fg)均明显降低(P＜0.01),但治疗组下降更趋明显(P＜0.05);对照组3例发生主要不良心血管事件(MACE),治疗组均未发生MACE,两组比较差异无统计学意义(P＞0.05);两组在服药期间均无主要出血事件和次要出血事件发生.结论 脑心通胶囊可明显降低PCI术后10天气虚证、血瘀证积分,抑制血小板活化,保护血管内皮细胞,改善机体凝血功能,且不引起血小板减少和出血等药物不良反应.     

CYP3A5和GSTP1基因多态性与多西他赛联合塞替派治疗转移性乳腺癌近期疗效的相关性研究

 目的 获得中国人群药物代谢酶CYP3A5基因和GSTP1基因两个位点的多态性及其与转移性乳腺癌近期疗效的相关性。方法 所有患者均采用多西他赛联合塞替派化疗方案,对患者每2周期疾病控制率（disease control rate, DCR）进行评估。采用基质辅助激光解吸电离飞行时间质谱（atrix assisted laser desorption ionization/ time of flight, MALDI-TOF）确定两个位点的基因型,比较不同基因型与该化疗方案近期疗效的关系。结果 93例转移性乳腺癌患者中具有CYP3A5 A6986G纯合突变型（GG）的DCR（77.8%）,显著高于AA+AG基因型的（57.4%） ( P<0.05);具有GSTP1 A313G突变型（AG+GG）的DCR（81.6%）显著高于野生型（AA）（57.4%）(P<0.05);对两个基因多态性位点的联合分析显示,同时具有GSTP1 AG+GG和CYP3A5 GG基因型的DCR最高,为84.2% (P<0.05)。结论 CYP3A5和GSTP1的基因多态性与化疗疗效有关, GSTP1 A313G突变型（AG+GG）和/或CYP3A5 A6986G纯合突变型（GG）的患者使用多西他赛联合塞替派方案近期化疗疗效最好,可为临床用药提供参考。     

升板方对SD大鼠CYP3A1酶活性的影响

目的:研究升板方对于SD大鼠肝微粒体CYP3A1酶活性的影响,为临床化疗联合用药方案提供参考。方法:将25只SD雄性大鼠随机分为升板方高(8.645 g/kg)、中(4.322 g/kg)、低(2.161 g/kg)地塞米松诱导组(灌胃100 mg/kg,1次/d,连续3 d),及空白对照组(灌胃给予生理盐水,10 mL/kg,2次/d,连续14 d)。升板方各剂量组均灌胃给药,2次/d,连续14 d。以睾酮为底物探针,建立稳定、可靠的检测大鼠CYP3A1酶代谢活性的HPLC方法,考察体外代谢体系最佳的孵育时间、最佳蛋白浓度、最佳底物浓度,在最佳孵育条件下根据大鼠肝微粒体转化生成6β-羟基睾酮的速率,评价各组大鼠肝药酶的活性。结果:在大鼠肝微粒体孵育体系,睾酮代谢为6β羟基睾酮反应的最佳孵育时间是10 min,最佳酶蛋白浓度是0.25 mg/mL,最佳底物浓度为200μmol/L。在最佳孵育条件下,升板方高、中、低剂量组及空白对照组、地塞米松诱导组6β-羟基睾酮生成速率分别是:(55.82±5.97)、(65.10±6.83)、(60.89±6.53)、(62.17±6.55)、(126.73±15.40)μmol/(L.mg pro.min)。经统计学检验,升板方高中低剂量组与地塞米松组反应速率的差异有统计学意义(P0.05),与生理盐水组无统计学差异。而升板方各剂量组间均无统计学差异。结论:升板方对大鼠肝药酶CYP3A1酶活性无诱导作用。     

CYP1B1 and hormone-induced cancer

Cancers in hormone-responsive tissues (e.g., breast, ovary, endometrium, prostate) occur at high incidence rates worldwide. However, their genetic basis remains poorly understood. Studies to date suggest that endogenous/exogenous oestrogen and environmental carcinogens may play a role in development and/or progression of hormone-induced cancers via oxidative oestrogen metabolism. Cytochrome P450 1B1 is a key enzyme in its oestrogen metabolism pathway, giving rise to hydroxylation and conjugation. Although CYP1B1 is expressed in many cancers, particularly high levels of expression are observed in oestrogen-mediated disease. CYP1B1 is more readily found in tumour tissue compared to normal. Given the role of CYP1B1 in pro-carcinogen and oestrogen metabolism, polymorphisms in CYP1B1 could result in modifications in its enzyme activity and subsequently lead to hormone-mediated carcinogenesis. CYP1B1 may also be involved in progression of the disease by altering the tissue response to hormones and clinical response to chemotherapy. The exact mechanism behind these events is complex and unclear. Only a few functional single nucleotide polymorphisms of CYP1B1 are known to result in amino acid substitutions and have been extensively investigated. Studies examining the contribution of different CYP1B1 alleles to hormone-mediated cancer risks are inconsistent. The main focus of this review is to appraise the available studies linking the pathogenesis of the hormone-induced cancers to various CYP1B1 polymorphisms. Additionally, we explore the role of a neuronal protein, γ-synuclein, in CYP1B1-mediated pathogenesis.     

Pharmacogenetics of anti-estrogen treatment of breast cancer

A major effort is underway to select genetic polymorphisms potentially relevant to the clinical efficacy and safety of endocrine treatment of breast cancer. Genetic factors of the host that affect the metabolism of tamoxifen, a widely used drug for the adjuvant treatment of breast cancer, have received particular attention. Cytochrome P450 isoform 2D6 (CYP2D6) is a key step in the metabolism of tamoxifen to its active moiety endoxifen. Women with functionally deficient genetic variants of CYP2D6 who are given drugs that inhibit CYP2D6 are exposed to low endoxifen plasma levels and may enjoy reduced benefits from tamoxifen treatment. Therefore, CYP2D6 status may be an important predictor of the benefits of tamoxifen to an individual; unfortunately, the data are not uniformly concordant, and definitive evidence that would suggest the routine analysis of CYP2D6 before commencing tamoxifen treatment is not yet available. Recent research has focused on the role UDP-glucuronosyltransferases, a family of metabolizing enzymes that play an important role in the metabolic clearance of tamoxifen and of the aromatase inhibitors as well, and how interindividual differences in these enzymes may play a role in the clinical outcome upon administration of anti-estrogen treatment. In conclusion, whether a pharmacogenetic profile should be obtained prior to initiating tamoxifen therapy is currently a matter of debate, although summing up all the scientific evidence available on this issue it appears that the genetic screening would be an useful support for clinical decision making in selected patients.