微信号：callme_hr
扫码加一览职业生涯导师微信好友
深圳市一览网络股份有限公司（股票代码：833680）
版权所有 &研究内容/药物流行病学[医学学科]
人群中药物利用情况和药物效应分布；研究的最终目标是给医疗单位、预防部门、药政管理部门及社会大众提供有关人群中药物利用及药品安全性、有效性的信息，为合理用药提出有利的意见和建议，从而使药品的开发、、、及使用更趋于合理。
工作重点：是药物不良反应(adverse&drug&reaction,ADR)监测在深度和广度上获得发展和提高。
研究方法/药物流行病学[医学学科]
药物流行病学（1）描述性研究方法，研究某一人群用药后发生不良反应的分布状态，通过比较分析，提示某种可能性，为进一步研究打下基础。
（2）分析性研究方法，包括病例对照研究和队列。
1）病例对照研究又称回顾性研究，是药物上市后研究的主要方法之一。
2）队列研究又称定群研究或群组研究，在未患所要研究疾病的人群中将暴露于某药物的人群作为暴露组，未暴露于某药物者作对照组，检验并比较二者的发病率或检验二者的归因危险程度。
（3）实验性研究方法
1）随机对照临床试验，将病人随机分成试验组和对照组，对照组给予某种安慰剂或参照处理，然后评价药物的效果。医.学教育网搜集整理临床试验特别要注意随机、对照和盲法处理三点。
2）社区实验，主要是在开展的人群干预试验。
实施价值/药物流行病学[医学学科]
（1）样本更大，数据估测更确切；
（2）可长期进行；
（3）可在特殊中进行；
（4）可研究其他疾病、其他药物对效应的影响；
（5）可进行药物应用的研究；
（6）可进行超量用药对人体影响力的研究；
（7）可进行药物经济学研究。
设计原则/药物流行病学[医学学科]
第一，首先要明确本次研究的目的和研究推论的总体人群。进一步要根据目的选择正确的研究方法，并明了各种方法论证因果关系的强度；在研究设计过程中要始终坚持代表性、可靠性、可比性、显著性原则。
第二，要明确定义药物暴露。药物流行病学研究的暴露因素是药物，而药物的使用常随时间改变，也不象年龄、性别、产次等人口学变量可以清楚地定义，因此对所研究的药物必须按服用时间、剂量和疗程给予明确的规定，应尽可能地定量。
第三，要明确定义异常结局。药物流行病学经常以疾病作为研究的结局，因此，疾病发生的时间首先要明确定义，只有肯定是服药后发生的疾病才能作为不良反应研究的结局；研究结局的时间窗口也要考虑。
第四，要注意控制混杂因素和偏倚。药物暴露与不良反应之间的关系经常受、、其他疾病和合并用药等因素的影响，因此药物调查研究中必须对这类混杂因素进行分析和控制。
第五，正确使用统计分析方法。如果选用的统计方法不恰当或对的定义、分组不正确，可能得出错误的结论。最后，要谨慎地解说研究结果。药物流行病学研究，尤其是观察性研究中不可避免地存在一些偏倚，因此这些研究中发现的药物不良反应或有益作用必须遵循因果关系推断的原则合理地解说，以免引起公众不必要的混乱。
&|&相关影像
互动百科的词条（含所附图片）系由网友上传，如果涉嫌侵权，请与客服联系，我们将按照法律之相关规定及时进行处理。未经许可，禁止商业网站等复制、抓取本站内容；合理使用者，请注明来源于。
登录后使用互动百科的服务，将会得到个性化的提示和帮助，还有机会和专业认证智愿者沟通。
此词条还可添加&
编辑次数：7次
参与编辑人数：3位
最近更新时间： 10:21:24
贡献光荣榜百度拇指医生
&&&普通咨询
您的网络环境存在异常，
请输入验证码
验证码输入错误，请重新输入关于药物知识医学英语阅读_医学英语
关于药物知识医学英语阅读
学习啦【医学英语】 编辑：焯杰
　　下面学习啦小编为大家带来关于药物知识医学英语阅读，欢迎大家学习!
　　药物知识医学英语阅读：药物吸收
　　Process of drug movement from the administration site to the systemic circulation.
　　Drug absorption is determined by physicochemical properties of drugs, their formulations, and routes of administration. Drug products--the actual dosage forms (eg, tablets, capsules, solutions), consisting of the drug plus other ingredients--are formulated to be administered by various routes, including oral, buccal, sublingual, rectal, parenteral, topical, and inhalational. A prerequisite to absorption is drug dissolution. Solid drug products (eg, tablets) disintegrate and deaggregate, but absorption can occur only after drugs enter solution.
　　Transport Across Cell Membranes
　　When given by most routes (excluding IV), a drug must traverse several semipermeable cell membranes before reaching the systemic circulation. These membranes are biologic barriers that selectively inhibit the passage of drug molecules and are composed primarily of a bimolecular lipid matrix, containing mostly cholesterol and phospholipids. The lipids provide stability to the membrane and determine its permeability characteristics. Globular proteins of various sizes and composition are em they are involved in transport and function as receptors for cellular regulation. Drugs may cross a biologic barrier by passive diffusion, facilitated passive diffusion, active transport, or pinocytosis.
　　Passive diffusion: In this process, transport across a cell membrane depends on the concentration gradient of the solute. Most drug molecules are transported across a membrane by simple diffusion from a region of high concentration (eg, GI fluids) to one of low concentration (eg, blood). Because drug molecules are rapidly removed by the systemic circulation and distributed into a large volume of body fluids and tissues, drug concentration in blood is initially low compared with that at the administration site, producing a large gradient.
　　The diffusion rate is directly proportional to the gradient but also depends on the molecule's lipid solubility, degree of ionization, and size and on the area of the absorptive surface. Because the cell membrane is lipoid, lipid-soluble drugs diffuse more rapidly than relatively lipid-insoluble drugs. Small molecules tend to penetrate membranes more rapidly than large ones.
　　Most drugs are weak organic acids or bases, existing in un-ionized and ionized forms in an aqueous environment. The un-ionized form is usually lipid soluble and diffuses readily across cell membranes. The ionized form cannot penetrate the cell membrane easily because of its low lipid solubility and high electrical resistance, resulting from its charge and the charged groups on the cell membrane surface. Thus, drug penetration may be attributed mostly to the un-ionized form. Distribution of an ionizable drug across a membrane at equilibrium is determined by the drug's pKa (the pH at which concentrations of un-ionized and ionized forms of the drug are equal) and the pH gradient, when present. For a weak acid, the higher the pH, the lower the ratio of un-ionized to ionized forms. In plasma (pH, 7.4), the ratio of un-ionized to ionized forms for a weak acid (eg, with a pKa of 4.4) is 1:1000; in gastric fluid (pH, 1.4), the ratio is reversed (1000:1). When the weak acid is given orally, the concentration gradient for un-ionized drug between stomach and plasma tends to be large, favoring diffusion through the gastric mucosa.
　　At equilibrium, the concentrations of un-ionized drug in the stomach and in the plasma are equal because only un-ionized drug can pen the concentration of ionized drug in the plasma would then be about 1000 times greater than that in the stomach. For a weak base with a pKa of 4.4, the outcome is reversed. Thus theoretically, weakly acidic drugs (eg, aspirin) are more readily absorbed from an acid medium (stomach) than are weak bases (eg, quinidine). However, whether a drug is acidic or basic, most of its absorption occurs in the small intestine.
　　Facilitated passive diffusion: For certain molecules (eg, glucose), the rate of membrane penetration is greater than expected from their low lipid solubility. One theory is that a carrier component combines reversibly with the substrate molecule at the cell membrane exterior, and the carrier-substrate complex diffuses rapidly across the membrane, releasing the substrate at the interior surface. Carrier-mediated diffusion is characterized by selectivity and saturability: The carrier transports only substrates with a relatively specific molecular configuration, and the process is limited by the availability of carriers. The process does not require energy expenditure, and transport against a concentration gradient does not occur.
　　Active transport: This process is characterized by selectivity and saturability and requires energy expenditure by the cell. Substrates may accumulate intracellularly against a concentration gradient. Active transport appears to be limited to drugs structurally similar to endogenous substances. These drugs are usually absorbed from sites in the small intestine. Active transport processes have been identified for various ions, vitamins, sugars, and amino acids.
　　Pinocytosis: Fluid or particles are engulfed by a cell. The cell membrane invaginates, encloses the fluid or particles, then fuses again, forming a vesicle that later detaches and moves to the cell interior. This mechanism also requires energy expenditure. Pinocytosis probably plays a minor role in drug transport, except for protein drugs.
　　必备医学知识阅读：药物生物利用度
　　The physicochemical properties of a drug govern its absorptive potential, but the properties of the dosage form (which partly depend on its design and manufacture) can largely determine drug bioavailability. Differences in bioavailability among formulations of a given drug can have clinical significance. Thus, the concept of equivalence among drug products is important in making clinical decisions. Chemical equivalence refers to drug products that contain the same compound in the same amount and that meet curren however, inactive ingredients in drug products may differ. Bioequivalence refers to chemical equivalents that, when administered to the same person in the same dosage regimen, result in equivalent concentrations of drug in blood and tissues. Therapeutic equivalence refers to drug products that, when administered to the same person in the same dosage regimen, provide essentially the same therapeutic effect or toxicity. Bioequivalent products are expected to be therapeutically equivalent.
　　Sometimes therapeutic equivalence may be achieved despite differences in bioavailability. For example, the therapeutic index (ratio of the maximum tolerated dose to the minimum effective dose) of penicillin is so wide that moderate blood concentration differences due to bioavailability differences in penicillin products may not affect therapeutic efficacy or safety. In contrast, bioavailability differences are important for a drug with a relatively narrow therapeutic index.
　　The physiologic characteristics and comorbidities of the patient also affect bioavailability.
　　Absorption rate is important because even when a drug is absorbed completely, it may be absorbed too slowly to produce a therapeutic blood level quickly enough or so rapidly that toxicity results from high drug concentrations after each dose.
　　Causes of Low Bioavailability
　　When a drug rapidly dissolves and readily crosses membranes, absorption tends to be complete, but absorption of orally administered drugs is not always complete. Before reaching the vena cava, a drug must move down the GI tract and pass through the gut wall and liver, common site thus, a drug may be metabolized (first-pass metabolism) before it can be measured in the systemic circulation. Many drugs have low oral bioavailability because of extensive first-pass metabolism. For such drugs (eg, isoproterenol, norepinephrine, testosterone), extraction in these tissues is so extensive that bioavailability is virtually zero. For drugs with an active metabolite, the therapeutic consequence of first-pass metabolism depends on the contributions of the drug and the metabolite to the desired and undesired effects.
　　Low bioavailability is most common with oral dosage forms of poorly water-soluble, slowly absorbed drugs. More factors can affect bioavailability when absorption is slow or incomplete than when it is rapid and complete, so slow or incomplete absorption often leads to variable therapeutic responses.
　　Insufficient time in the GI tract is a common cause of low bioavailability. Ingested drug is exposed to the entire GI tract for no more than 1 to 2 days and to the small intestine for only 2 to 4 h. If the drug does not dissolve readily or cannot penetrate the epithelial membrane (eg, if it is highly ionized and polar), time at the absorption site may be insufficient. In such cases, bioavailability tends to be highly variable as well as low. Age, sex, activity, genetic phenotype, stress, disease (eg, achlorhydria, malabsorption syndromes), or previous GI surgery can affect drug bioavailability.
　　Reactions that compete with absorption can reduce bioavailability. They include complex formation (eg, between tetracycline and polyvalent metal ions), hydrolysis by gastric acid or digestive enzymes (eg, penicillin and chloramphenicol palmitate hydrolysis), conjugation in the gut wall (eg, sulfoconjugation of isoproterenol), adsorption to other drugs (eg, digoxin and cholestyramine), and metabolism by luminal microflora.
　　Assessment of Bioavailability
　　Assessment of bioavailability from plasma concentration-time data usually involves determining the maximum (peak) plasma drug concentration, the time at which maximum plasma drug concentration occurs (peak time), and the area under the plasma concentration-time curve. The plasma drug concentration increases with the
the peak is reached when the drug elimination rate equals absorption rate. Bioavailability determinations based on the peak plasma concentration can be misleading, because drug elimination begins as soon as the drug enters the bloodstream. The most widely used general index of absorpti the slower the absorption, the later the peak time. However, peak time is often not a good statistical measure because it is a discrete value that depends on frequency of blood sampling and, in the case of relatively flat concentrations near the peak, on assay reproducibility.
　　AUC is the most reliable measure of bioavailability. It is directly proportional to the total amount of unchanged drug that reaches the systemic circulation. For an accurate measurement, blood must be sampled frequently over a long enough time to observe virtually complete drug elimination. Drug products may be considered bioequivalent in extent and rate of absorption if their plasma-level curves are essentially superimposable. Drug products that have similar AUCs but differently shaped plasma-level curves are equivalent in extent but differ in their absorption rate-time profiles.
　　Single vs. multiple doses: Bioavailability may be assessed after single or repetitive (multiple) dosing. More information about rate of absorption is available after a single dose than after multiple dosing. However, multiple dosing more closely represents the usual clinical situation, and plasma concentrations are usually higher than those after a single dose, facilitating data analysis. After multiple dosing at a fixed-dosing interval for four or five elimination half-lives, the blood drug concentration should be at steady state (the amount absorbed equals the amount eliminated within each dosing interval). The extent of absorption can then be analyzed by measuring the AUC during a dosing interval. Measuring the AUC over 24 h is probably preferable because of circadian variations in physiologic functions and because of possible variations in dosing intervals and absorption rates during a day.
　　For drugs excreted primarily unchanged in urine, bioavailability can be estimated by measuring the total amount of drug excreted after a single dose. Ideally, urine is collected over a period of 7 to 10 elimination half-lives for complete urinary recovery of the absorbed drug. Bioavailability may also be assessed after multiple dosing by measuring unchanged drug recovered from urine over 24 h under steady-state conditions.
本文已影响 人
[关于药物知识医学英语阅读]相关的文章
看过本文的人还看了
1924人看了觉得好
2416人看了觉得好
2327人看了觉得好
【医学英语】图文推荐日，沙特阿拉伯阿卜杜拉国王医学研究中心（KAIMRC）医学研究平台主任MohamedBoudjelal博士访问药物研究所。药物研究所所…
日，药物所学术年会在所东楼五层会议室召开。所长蒋建东、党委书记陈晓光、副所长庾石山及广大科研人员参加了本次学术年…
内部办公系统
科研办公管理系统
数字信息检索系统
药物发现计算模拟平台
综合档案数字化管理系统
内部办公文件
核磁送样管理系统
核磁开放仪器预约系统
化合物管理系统
图书馆书目检索系统
计算机维护登记系统
新药研发动态追踪
北京协和药厂
中国药理学会
中国生物技术发展中心
中国医学科学院
国家科技重大专项}