Is the transport of drugs from the plasma to the tissues site of action, site of storage, site of biotransformation factors affecting distribution of drugs. Drug distribution 7 311 principles of veterinary pharmacology dr. Factors affecting drug distribution distribution of drugs throughout the body fluid is not equal. Differences in drug distribution among the tissue essentially arise as result of a number of factors. As the fluid passes through, water and nutrients are reabsorbed. Multiple choice questions concerning drug administration, drug metabolism. The speed with which drugs move in and out of the body varies widely among different people.
Absorption the main factor which relates to absorption of drugs is the route of administration. Factors affecting drug disposition and response flashcards. Study flashcards on 4 pharmacology drug distribution at. The entry rate of a drug into a tissue depends on the rate of blood flow to the. The oral absorption of a drug is a complex process depending upon these factors and their. In meningitis and encephalitis, the bbb becomes more permeable and thus polar antibiotics such as penicillin g and ampicillin which do not normally cross it, gain assess to the brain. Factors affecting pharmacokinetics of drugs medicilon inc. I found the book absorbing, questions are well framed. As drug absorption occurs, drug transfers to the blood, resulting in a concentration gradient. Organs of high perfusion, protein binding, molecular size. After a drug enters the systemic circulation, it is distributed to the bodys tissues. Physicochemical properties of the drug concentration gradient plasma protein binding.
Distribution is the study of how the blood stream carries a drug throughout the body. Distribution of drugs to specific tissues a is independent of blood flow to the organ b is independent of the solubility of the drug in that tissue c depends on the unbound drug concentration gradient between blood and tissue. Start studying pharm 5 factors affecting drug distribution. Pdf overview of factors affecting oral drug absorption. Distribution in pharmacology is a branch of pharmacokinetics which describes the reversible transfer of a drug from one location to another within the body once a drug enters into systemic circulation by absorption or direct administration, it must be distributed into interstitial and intracellular fluids. Clinical pharmacokinetics is the application of pharmacokinetic principles to the safe. Drug distribution an overview sciencedirect topics. Factors affecting drug distribution through infusion by the infusion physics study group 051809 convection enhanced delivery ced is a technique used to distribute drugs inside the brain parenchyma using pressure to cause the movement of infused fluid. Inside the body, drugs move in the blood to different parts of the body. The location, extent, and distribution are dependent on the drugs physicochemical properties and individual patient characteristics such as organ. This animation presents 4 major factors that effect a drugs distribution in the body.
Lipid water solubility coefficient is the ratio of dissolution of drug in lipid as compared to water. Describe the physiology of drug distribution in the body. Drug distribution to tissues clinical pharmacology. Renal excretion factor i most likely to be sensitive to drug ionization state. The process of transferring a drug from the bloodstream to tissues is referred to as distribution. Physiologic drug distribution and protein binding applied. The drugs are present in free or bound form and different processes or mechanisms affect their distribution. The factors affecting absorption of drugs are related both to the drugs and to the body factors related to drugs. Changes in ph occuring in disease may also affect drug distribution. Pharm tech chapter 11 factors affecting drug activity. Many factors can affect a drugs absorption, distribution, metabolism, excretion, and ultimate effect. Factors affecting drug distribution through infusion. Drug distribution is a subject that is covered in a branch of.
Organs of high perfusion, protein binding, molecular size, and polarity. The use of mathematical principles and methods to explain the plasma concentration with time changes in a discipline. Apparent volume of distribution is the theoretical volume that would have to be available for drug to disperse in if. Test your expertise of the subject with a printable worksheet and an interactive quiz. Variations government medical college and hospital.
Pharm 5 factors affecting drug distribution flashcards. Drug aborption, metabolism, transport, and drug excretion practice. Distribution distribution is the dispersion of the drug among the various organs or compartments within the body. Drug distribution to tissues clinical pharmacology msd manual. Drug distribution drugs msd manual consumer version. Explain how bioavailability can impact drug response and product selection. Korawuth punareewattana faculty of veterinary medicine, khon kaen university a free powerpoint ppt presentation displayed as a flash slide show on id. Factors that affect the distribution of drugs in the body are lipid solubility, the bloodbrain barrier, protein binding, and the presence of active and passive transport mechanisms.
Drug distribution is affected by many factors, including plasma or tissue protein binding, body weight, body composition, and body fluid spaces 8. The rate of movement of a drug out of circulation will depend on its degree of ionization and therefore its pka. The following table highlights some of these other factors. Transfer of drugs from bloodstream to tissues around the body. Start studying chapter 1 factors that affect drug distribution. Genetic factors plasma protein binding specific drug receptor sites in tissues regional blood flow.
Distribution is generally uneven because of differences in blood perfusion, tissue binding eg, because of lipid content, regional ph, and permeability of cell membranes. Describe two types of drug interaction and explain how. List and describe the four factors that affect the rate of drug distribution. When a doctor prescribes you a pill or injects you with a medication in the hospital, it may seem like a really simple thing to an outsider. The apparent volume of distribution vd, has been devised to describe the distribution of the drug. Human variablitiy, disease states, adverse drug reations, drugdrug intereactions, drugdiet intereactions. Other factors affecting drug absorption and distribution. Drug distribution is the process of delivering a drug from the bloodstream to the tissues of the body especially the tissue s where its actions are needed. Dhanvanthari institute of pharmaceutical sciences, kothagudem, khammam. Factors affecting distribution of drug tissue permeability of drug 1.
Factors affecting drug absorption and distribution. In a patient suffering from ccf the perfusion rate to the entire body decreases affecting distribution of all drugs. Pharm tech chapter 11 factors affecting drug activity 44 questions by ashleycream last updated. Find out what you know about the biotransformation of drugs. Clinical pharmacokinetics is the application of pharmacokinetic principles to the safe and effective therapeutic management of drugs in an individual patient. Overview of factors affecting oral drug absorption. The process by which a drug reversibly leaves the blood stream and enters the interstitium extracellular fluid andor the cells or tissues.
Drug factors lipid solubility of the drugs molecular weight of the drugs pka of drug 7. The factors affecting absorption of drugs are related both to the drugs and to the body. And one thing should be remembered that in vitro disintegration test gives no means of a guarantee of drugs b. After a drug is absorbed into the bloodstream see drug absorption, it rapidly circulates through the body.
The systemic absorption of a drug is dependent on 1 the physicochemical properties of. List two physiologic factors that can alter each of the processes of absorption, distribution, and excretion. In addition to protein availability, other factors may affect drug absorption and distribution in the body as a whole or at specific sites within the body. It is defined as the volume of fluid required to contain the total amount of drug. Factors that affect the rate of drug distribution 704. Elimination which involves irreversible loss of drug from the body. The action of a drug requires the presence of an adequate concentration of the drug in the fluid bathing the target tissue, and this, in turn, is determined by the dynamic relationship between absorption into the plasma following administration, the extent and rate of its distribution and the rate of inactivation by the body.
Compare the roles of passive diffusion and carriermediated transport in drug absorption. In the kidney, most of the fluid in the blood is released into one end of the nephron. The drug distribution is usually varied, and depends on several factors such as. No part of this ebook may be reproduced in any form, by photostat, microfilm. Drug distribution once a drug enter in to the blood stream, the drug is subjected to a number of processes called as disposition processes that tend to lower the plasma concentration. Apparent volume of distribution amount of drug in body drug. Metabolism is the study of how a drug is degraded within the body and excretion is the study. Indeed, these results raise many questions, such as. Possible factors affecting this stage include the rate of blood flow perfusion to the tissue, the tissue mass itself, and vascular and tissue membrane permeability.
Greater the lipid water solubility coefficient, more is the lipid solubility of the drug and greater is the absorption. Learn vocabulary, terms, and more with flashcards, games, and other study tools. As the name implies, this is the stage when the drug is distributed to the bodys tissues. Drug distribution can be defined as the movement of drug between blood and extravascular tissues. In brain, perfusion or membrane permeability limits drug transport or distribution. Chapter 1 factors that affect drug distribution flashcards. Basic pharmacokinetics sample chapter pharmaceutical press. There are four factors that will influence the pharmacokinetic drugs test. Distribution of a drug is not uniform throughout the body because different tissues receive the drug from plasma at different rates and to different extents. Factors affecting distribution factors affecting distribution of drug tissue permeability of drug. Distribution which involves reversible transfer of a drug between compartments. Factors effecting on drug distribution ashok kari 1, gandhu sateesh, bharatha suresh, bodavula samba siva rao2 1. In the case of two compartment model vss gives best estimate of total volume of drug distribution 28.
Distribution of drug throughout the body is not uniform, because the different tissues receive the. Thiopental diffuses readily, thus perfusion limits its distribution. Introduction to pharmacokinetics and pharmacodynamics ashp. Introduction to pharmacokinetics and pharmacodynamics. Study factors affecting drug disposition and response flashcards from brittany parsonss class online, or in brainscapes iphone or android app. Drug distribution refers to the movement of a drug to and from the blood and various tissues of the body for example, fat, muscle, and brain tissue and the relative proportions of drug in the tissues. Absorption is the study of how, once a drug is ingested, it moves from the stomach to the blood stream. Click here to visit our frequently asked questions about html5 video. Physiological considerations in absorption are blood flow, total surface area, time of arrival of the drug and time of drug at absorption site.
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