华法林抗凝个体化治疗研究进展

华法林是临床使用最多的口服抗凝药,其治疗窗窄,剂量个体差异大,容易发生出血或栓塞的风险,如何准确地调整华法林剂量一直是其抗凝治疗的关键及研究热点。多种因素均会影响华法林剂量,尤其是遗传因素（主要是CYP2C9、VKORC1及CYP4F2基因）。近十年来,基于药物基因组学的剂量预测模型和药代动力学药效学的快速发展,为华法林个体化治疗提供了新的契机。该文结合国内外各种华法林稳定剂量预测模型研究,总结影响华法林剂量相关因素的最新研究进展,旨在为华法林个体化治疗提供参考和指导依据。     

华法林的药物基因组学及其合理应用

华法林为香豆素类抗凝血药,广泛用于防治血栓栓塞性疾病。华法林治疗窗窄,剂量个体差异大,临床应用中易出现出血合并症。近年研究表明,华法林个体剂量差异与影响华法林代谢和作用的多个基因多态性如CYP2C9、VKORC等有关。本文回顾华法林的药物基因组学研究进展,为临床合理应用华法林提供参考。     

基因多态性与华法林的起始给药剂量的相关性研究

目的:探讨CYP2C9与VKORC1基因多态性对于个体华法林的起始给药剂量的影响,为临床个体化使用华法林提供实验依据。方法:选取某院2014年1月~2016年1月收治的232例心血管疾病患者,平均分为对照组和观察组。对照组采取常规华法林治疗模式,观察组通过基因测序法检测116例患者CYP2C9、VKORC1基因多态性后,分基因型个性化用药,检测不同给药剂量的INR值,统计并分析两组之间的华法林起始给药剂量、治疗效果及不良事件的发生率。结果:相比于对照组,观察组的华法林起始剂量降低,具有统计学差异(P0.05);不良反应发生率明显减少。结论:在个体化使用华法林的临床疗效中,CYP2C9和VKORC1基因与相应华法林的起始给药剂量及最终治疗疗效存在着密不可分的联系,对心血管疾病给药剂量具有重要性。     

基因多态性对华法林剂量影响的研究进展

目的:了解基因多态性对华法林剂量的影响以及其在临床的应用研究,以期为华法林的精准用药提供参考。方法:查阅近年来国内外相关文献,对华法林基因多态性以及其在临床的应用研究进行归纳和总结。结果与结论:影响华法林剂量的主要基因为细胞色素P450(CYP)2C9和维生素K氧化物还原酶复合体1(VKORC1)。华法林主要由CYP2C9酶完成代谢,与其代谢最密切的突变型为CYP2C9*2和CYP2C9*3。携带CYP2C9*2、CYP2C9*3等位基因的患者比野生型CYP2C9*1/*1患者有更高的过度抗凝和出血风险,提示携带CYP2C9*2、CYP2C9*3等位基因的患者所需华法林的剂量低于野生型CYP2C9*1/*1患者。VKORC1的酶活性直接影响华法林的抗凝效果,VKORC1基因与华法林早期治疗的影响较大。CYP4F2、γ-谷氨酰基羟化酶(GGCX)、载体蛋白E(APOE)、微粒体环氧化物水纤酶编码基因(EPHX1)等基因与华法林的剂量均呈现一定的相关性。华法林基因检测的临床应用主要依据FDA建议的基因多态性与华法林初始剂量对照表和剂量计算公式,但与华法林的给药剂量相关的两项临床研究结果并不一致,检测基因并结合计算公式将华法林应用于临床是否具有意义仍存在争议。     

基于CYP2C9和VKORC1基因多态性预测老年房颤患者使用华法林的稳定剂量

目的:探讨CYP2C9和VKORC1基因多态性对房颤患者华法林稳定剂量的影响,建立适合汉族人群老年房颤患者的华法林给药模型,指导华法林个体化抗凝治疗。方法:对200例口服华法林抗凝的老年患者进行CYP2C9和VKORC1基因分型,比较不同基因型房颤患者华法林日均稳定剂量的差异。采用多元线性回归分析法依据CYP2C9和VKORC1基因型、年龄、身高、体质量、合并用药建立华法林稳定剂量计算公式。结果:INR稳定在2.0～3.0之间时,CYP2C9*1/*1基因型患者日均使用华法林剂量(3.87±0.71)mg显著高于CYP2C9*3基因型患者(1.05±0.59)mg;VKORC1-1639AA基因型患者日均使用华法林剂量(2.94±1.03)mg显著低于VKORC1-1639GA/GG基因型患者(5.76±1.12)mg。通过多元线性回归分析得出华法林稳定剂量公式,建立的回归模型中包含年龄、体质量、合并用药、CYP2C9*3和VKORC1-1639基因型,该模型能解释约56.5%个体间华法林剂量差异。结论:基于CYP2C9和VKORC1基因多态性建立的华法林稳定剂量预测公式,能帮助指导华法林在老年房颤患者中的抗凝治疗。     

临床药师参与心脏瓣膜置换术后华法林药物基因导向个体化抗凝治疗

目的:尝试和建立以基因为导向的华法林个体化抗凝治疗模式,以期提高抗凝疗效,降低患者抗凝治疗风险。方法:临床药师参与心脏瓣膜置换术后患者的抗凝管理,积极探讨患者基因差异对华法林抗凝疗效的影响。结果:心脏瓣膜置换术后患者需接受华法林抗凝治疗,华法林疗效存在明显个体差异,而基因多态性是导致华法林剂量差异的主要原因。结论:传统经验抗凝治疗模式存在一定的盲目性和潜在的危险性。     

基因分型指导肺栓塞患者的华法林个体化药物治疗

目的探讨如何利用基因检测的结果指导华法林的个体化给药。方法参与2例初次使用华法林的肺栓塞患者治疗,通过基因分型计算华法林使用剂量。结果通过基因检测,指导华法林个体化给药,优化给药方案。结论临床药师利用药物基因检测的工具,指导华法林个体化给药,实现药物个体化治疗的目标。     

华法林基因导向的个体化抗凝研究进展

华法林是临床广泛使用的抗凝药，但其疗效存在明显个体差异，其中基因多态性是导致华法林剂量差异主要影响因素。本文查阅相关文献，综述与华法林剂量相关的基因，为临床华法林个体化应用提供参考。     

CYP2C9和VKORC1基因多态性对老年房颤患者华法林稳定剂量影响及分析

摘要：目的:探讨CYP2C9和VKORC1基因多态性对老年房颤患者华法林稳定剂量的影响,建立适合汉族人群老年房颤患者的华法林给药模型,指导华法林个体化抗凝治疗。方法:对195例口服华法林抗凝的老年患者进行CYP2C9和VKORC1基因分型,比较不同基因型房颤老年患者华法林日均稳定剂量差异。采用多重线性回归分析法依据CYP2C9和VKORC1基因型、年龄、体表面积（BSA）、胺碘酮建立华法林稳定剂量计算公式。结果:国际标准化比值（INR）稳定在2.0～3.0之间时,CYP2C9*1/*1基因型患者日均华法林剂量（3.10±0.91） mg,显著高于CYP2C9*1/*3与CYP2C9*3/*3基因型患者的（2.10±0.89） mg和（1.25±0.00） mg; VKORC1-1639AA基因型患者日均华法林剂量（2.86±0.88） mg,显著低于VKORC1-1639GA/GG基因型患者的（3.68±0.88） mg和（6.38±0.91） mg（P<0.05）。通过多元线性回归分析得出华法林稳定剂量公式,建立的回归模型中包含年龄、BSA、胺碘酮、CYP2C9和VKORC1-1639基因型,该模型能解释约60.4%个体间华法林剂量差异。结论:基于CYP2C9和VKORC1基因多态性建立的华法林稳定剂量预测公式,能帮助指导华法林在老年房颤患者中的抗凝治疗。     

中国人群CYP4F2基因多态性对华法林抗凝作用的影响

目的:研究中国人群中CYP4F2基因多态性对华法林抗凝作用的影响。方法:本研究纳入我院应用华法林进行抗凝治疗的患者,对患者CYP4F2基因多态性位点用连接酶检测反应进行检测,以国际标准化比值(INR)作为监测指标,统计学分析基因位点的多态性与华法林用药剂量个体间差异的相关性。结果:207例样品中,CYP4F2基因突变率为22.2%,其中杂合子分型为35.7%,且达到遗传平衡。不同基因分型组间的华法林剂量未见显著性差异,但是携带T的患者华法林稳定剂量有逐步升高的趋势。结论:CYP4F2基因多态性对华法林稳定期剂量有影响但不显著。     

CYP2C9和VKORC1基因多态性对心脏瓣膜置换术后华法林维持剂量和抗凝效果的影响

目的:探讨CYP2C9和VKORC1基因多态性对华法林稳定维持剂量和抗凝治疗的影响,为建立心脏机械瓣膜置换术后患者的华法林个体化给药模型提供依据。方法:应用聚合酶链式反应-限制性片段长度多态性(PCR-RFLP)方法检测福州地区119例心脏机械瓣膜置换术后患者CYP2C9*3、CYP2C9-65G/C和VKORC1-1639A/G基因多态性。收集性别、年龄、体质量信息,同时记录华法林的稳定维持剂量、达标天数,观察抗凝过量、不良反应等指标。结果:CYP2C9*3和CYP2C9-65G/C基因型与低华法林维持剂量相关,VKORC1-1639A/G基因型与高华法林维持剂量相关。CYP2C9杂合体组患者抗凝过量危险性增加,但出血的危险性没有增加;携带CYP2C9和VKORC1突变等位基因的患者,抗凝达稳态时间延长。结论:患者用药前进行CYP2C9和VKORC1基因型检查,预测华法林用药剂量,可减少抗凝过量的发生,缩短剂量调整的时间。     

Increase in international normalized ratio after smoking cessation in a patient receiving warfarin

A 58-year-old man who was taking warfarin at a stable dosage was admitted to the hospital with a diagnosis of bacterial meningitis. Although he had previously been a smoker, after this admission, he decided to give up smoking. He was continued on his previous warfarin maintenance dosage when discharged, and his international normalized ratio (INR) soon began to climb substantially. When questioned, the patient reported no diet or lifestyle changes other than his smoking cessation. The patient's INR was stabilized at a warfarin dosage 23% lower than the maintenance dosage before he stopped smoking. This case report illustrates the potential for an interaction between warfarin and cigarette smoking and further suggests that the effect could be significant if a patient starts or stops smoking during warfarin therapy.     

中国汉族人群基于临床特征和基因型华法林个体化给药模型的研究

目的：评价中国汉族人群临床特征及基因型对华法林剂量的影响,并构建华法林给药模型,为临床华法林个体化给药提供参考。方法：按照设定标准选取某医院2011年1月至2013年10月行心脏瓣膜手术后接受华法林抗凝治疗并达到华法林稳定剂量的中国汉族人群203例,对纳入人群进行CYP2C9＊3、VKORC1-1639G/A基因多态性检测,结合基因型及患者临床特征,分析对华法林稳定剂量的影响,并采用多元逐步线性回归分析建立数学模型。结果：性别、吸烟、饮酒及高血压病史对华法林剂量无明显影响（P＞0.05）。华法林剂量与年龄呈负相关（r=-0.155,P=0.027）;与身高、体质量呈正相关（r=0.166、0.190,P=0.009、0.003）。CYP2C9＊3、VKORC1-1639G/A基因多态性对华法林剂量的影响在统计学上有统计学差异（P＜0.01）。拟合得到华法林给药模型D=2.855－1.173×CYP2C9（AC）＋0.020×W－0.024×A＋4.064×VKORC1（GG）＋1.486×VKORC1（GA）。结论：华法林的剂量受到年龄、身高、体质量及CYP2C9＊3、VKORC1-1639G/A基因多态性的影响,依据华法林给药模型可优化华法林个体化给药方案,但仍有待于临床进一步验证。     

胺碘酮和CYP2C9、VKORC1基因型对华法林抗凝效果的影响分析

分析胺碘酮在不同的CYP2C9和VKORC1分型患者对华法林的抗凝作用的影响。纳入从2008年9月至2009年11月某三甲医院应用华法林的入院患者,收集患者一般信息、合并用药及其他临床相关数据,检测患者VKORCl和CYP2C9基因型;比较使用或未使用胺碘酮治疗患者抗凝稳定期INR值及华法林用量,纳入基因分型进行华法林/胺碘酮相互作用的亚组分析。结果未发现胺碘酮应用患者华法林稳定期用量和INR值的统计学差异,基因型亚组差异无统计学意义。这说明院内短期合并使用胺碘酮患者对华法林稳定剂量和INR值无显著影响。     

基因多态性与华法林剂量需求关系的研究进展

华法林是最常应用的口服抗凝药之一.近年来关于华法林个体化用药的最大的研究进展是基于基因多态性的给药模型,以及大规模的随机对照临床试验用于评价给药模型的有效性和安全性.本文综述了与华法林剂量需求相关的药效学及药代动力学基因多态性;同时,介绍了基于基因多态性的华法林给药模型的最新进展,为临床华法林个体化用药提供参考.     

Effect of carbamazepine initiation and discontinuation on antithrombotic control in a patient receiving warfarin: case report and review of the literature

A 72-year-old Caucasian woman with paroxysmal atrial fibrillation had been taking warfarin therapy for 5 years with a stable international normalized ratio (INR). Her dentist then prescribed carbamazepine 200 mg/day to control facial nerve pain. At her next physician visit about 2 weeks after the start of the carbamazepine, the patient's INR had dropped from 3.3 to 1.3; she reported no contributing changes in her diet or warfarin dosage, nor had she taken other interacting drugs. Her warfarin dosage was increased, and the INR returned to the target range of 2.0-3.0 approximately 2 months later. The patient's INR remained stable for approximately 6 more months, until she had facial surgery. During that time, her warfarin was discontinued for 5 days, and the patient had stopped taking the carbamazepine because she had no pain. One month later, her INR increased from 2.2 to 3.6. She did not experience any thrombotic or hemorrhagic episodes. Warfarin undergoes hepatic metabolism through cytochrome P450 2C9, and carbamazepine induces this isoenzyme. Inducing warfarin metabolism necessitates an increase in the warfarin dosage to maintain the INR in the therapeutic target range. To our knowledge, this is the first report documenting the effect of the carbamazepine initiation and discontinuation in a patient receiving anticoagulation therapy with warfarin. In patients taking warfarin, clinicians should monitor the INR closely when carbamazepine is started or discontinued, or when either dosage is changed.     

Oral anticoagulant drug interactions with statins: case report of fluvastatin and review of the literature

A 67-year-old man receiving a stable maintenance dosage of warfarin experienced an increased international normalized ratio (INR) without bleeding when his atorvastatin therapy was switched to fluvastatin. His warfarin dosage was reduced and his INR stabilized. The fluvastatin was switched back to atorvastatin, and the warfarin dosage was increased to maintain the patient's goal INR. The literature supports a drug interaction between warfarin and fluvastatin due to the strong affinity of fluvastatin for the cytochrome P450 enzyme 2D6. This interaction has not been seen with atorvastatin. Lovastatin also reportedly has caused increases in INR when coadministered with warfarin. It is unclear whether simvastatin interacts with warfarin, but it may increase INRs slightly or increase serum simvastatin levels. One case report describes an interaction between simvastatin and the anticoagulant acenocoumarol, which resulted in an elevated INR. Pravastatin does not appear to interact with warfarin but has caused an increased INR when combined with the anticoagulant fluindione. Thus, until more definitive data are available, clinicians should monitor the INR closely after starting statin therapy in any patient receiving anticoagulation therapy.     

Difficulties in anticoagulation management during coadministration of warfarin and rifampin

The clinical significance of rifampin's induction of warfarin metabolism is well documented, but no published studies or case reports have quantified this interaction with respect to the international normalized ratio (INR). A patient receiving concomitant rifampin and warfarin to treat a mycobacterial infection and intraventricular thrombus, respectively, underwent routine INR testing at a pharmacist-managed anticoagulation clinic to assess his anticoagulation regimen. A 233% increase in warfarin dosage over 4 months proved insufficient to attain a therapeutic INR during long-term rifampin therapy More aggressive titration of the warfarin dosage was needed. In addition, a gradual 70% reduction in warfarin dosage over 4-5 weeks was necessary to maintain a therapeutic INR after rifampin discontinuation, demonstrating the clinically significant offset of this drug interaction. Extensive changes in warfarin dosage are required to attain and maintain a therapeutic INR during the initiation, maintenance, and discontinuation of rifampin.     

A simple technique for predicting maintenance dosage of warfarin — Is it better than empirical dosing?

Summary In a prospective, randomised trial the clinical utility of a predictive warfarin maintenance dosing technique was compared with the more commonly employed empirical dosing method. A preliminary study in 35 patients established the applied technique for predicting the maintenance dosage of warfarin from the prothrombin activity on Day 4 of initial standardised warfarin administration. Forty-three patients admitted with venous thrombotic disease were investigated. All received the same loading dose of warfarin (10 mg daily) until the prothrombin percentage activity (Normotest) was less than 25%.Significantly more patients were correctly stabilised when warfarin doses were based on prediction than when they were empirically adjusted (86% vs 50%). Also, the median number of days to achieve stable anticoagulation was lower (8 vs 11 days).It is concluded that this simple predictive technique to determine the maintenance dosage of warfarin is superior to empirical dosing.