The tissue permeability of a drug depends upon the physicochemical properties of the drugs as well as the physiologic barriers that restrict diffusion of the drug into tissues. Pd refers to the pharmacological effects elicited in the body by a drug. Describe factors affecting diffusion through lipid membrane describe factors affecting distribution into different body compartments mention clinical relevance of bioavailability, bioequivalence and volume of distribution definition pharmacokinetics what the body does to the drug. Pdf drug misuse and abuse are major health problems. Pdf commonly used drugs uses, side effects, bioavailability. Inside the body, drugs move in the blood to different parts of the body. 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. Factors affecting drug distribution rate of distribution membrane permeability. Jan 22, 2014 contents of the powerpoint on volume of distribution include. There are many factors that affect a drugs distribution throughout an organism, but pascuzzo considers that the most important ones are the following. Factors affecting drug absorption and distribution request pdf. Drug distribution drugs merck manuals consumer version. This animation presents 4 major factors that effect a drugs distribution in the body. Factors that affect the distribution of drugs in the body.
O factors affecting drug metabolism pharmaceutical chemistry. Factors affecting the clearance and biodistribution of polymeric. Contents of the powerpoint on volume of distribution include. Distribution and pharmacokinetics of methamphetamine in the. Background methamphetamine is one of the most toxic of the drugs of. Ratio of blood flow to tissue mass sa for drug transfer to tissue 4. Typically, distribution is much more rapid than elimination, is accomplished via the circulation, and is influenced by regional blood flow. Nov 07, 20 factors affecting drug distribution distribution of drugs throughout the body fluid is not equal. Jun 26, 2007 this animation presents 4 major factors that effect a drugs distribution in the body. Smaller size and less body water distribution issues smaller doses elderly. 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. Feb 27, 2019 drug distribution is a subject that is covered in a branch of pharmacology called pharmacokinetics. Each route of drug application presents special biopharmaceutic consideration in designing a drug product.
David nutt, leslie a king, william saulsbury, colin blakemore. This research project seeks to identify these factors and also determine in what way they may influence distribution logistics performance. Bumbaca d, wong a, drake e, reyes ae, 2nd, lin bc, stephan jp, et al. The following table highlights some of these other factors. There are many underlying chemical and physiological factors affecting the. Oct 24, 2014 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. Elimination which involves irreversible loss of drug from the body. Drug distribution drugs msd manual consumer version. After reading this article you will learn about the pharmaceutic factors affecting drug bioavailability. After a drug enters the systemic circulation, it is distributed to the bodys tissues. Example includes phenytoin, whose dose has to be increased during pregnancy specially second and third trimester.
Blood perfusion rate the rate at which blood perfuses to different organs varies widely. The ability of a drug to diffuse in polymers, its socalled. Affinity of drug for tissue constituents plasmatissue protein binding. The entry rate of a drug into a tissue depends on the rate of blood flow to the. Translational pharmacokinetics and pharmacodynamics of. Factors affecting drug distribution distribution of drugs throughout the body fluid is not equal. Elimination is further divided in to two process biotransformationmetabolism excretion the interrelationship between drug distribution, biotransformation and excretion and the drug in figure 1. Drug distribution to tissues clinical pharmacology. Adme of biologicswhat have we learned from small molecules. The bioavailability of active drug can be varied from rapid and complete absorption to a slow, sustained rate of absorption or. The process by which a drug reversibly leaves the blood stream and enters the interstitium extracellular fluid andor the cells or tissues. Membrane permeability tends to restrict the transfer and distribution of drugs once they are delivered to the tissue. Among other reasons, people respond to drugs differently because of genetic differences, because they may be taking. Factors affecting distribution of drugs include those related to the drug and those related to the body.
Selfreported data gathered from females 12 to 15 years of age in two northwestern communities in the united states showed an association among gender identity, peer and parental relationships, and substance use. Drug distribution transfer of drug between regions of the body distribution between bloodplasma, tissues. Overview of response to drugs msd manual consumer version. Beaker connected to another beaker which contains csf eg drug concentration sharply increases spike then plateaus as no elimination d. Factors affecting drug action drug dosage and theraphy. Most of the time cytochrome p450 is involved leading to increased synthesis of new enzymes. Smaller sized drugs are more extensively distributed. Biotransformation is significantly affected by a number of factors, these include 1.
A drug must diffuse through a variety of biological membranes during its time course in the body. Distribution pattern of scatter of specified amount of drug among various locations in the body volume of distribution vd metabolism enzyme catalysed chemical transformation of drugs within living organism elimination excretion of drug metabolites outside the body clearance cl half life t. Factors affecting drug abuse 2 abstract this article explores factors influencing adolescent female substance use in rural communities. Cultural factors as well as market factors in drug access are likely to. Drug distribution in the body rate of distribution factors influencing the rate of distribution the rate of distribution of a drug between the blood and a tissue can be limited either by perfusion or by diffusion. In addition, urinary excretion was the major excretion route. Differential drug response as a function of age emblebi. Factors affecting drug abuse in adolescent females in rural.
World report united nations office on drugs and crime. Many factors can affect a drugs absorption, distribution, metabolism, excretion, and ultimate effect. Factors influencing the design and performance of oral. Factors affecting drug abuse in adolescent females in. Metabolism is the study of how a drug is degraded within the body and excretion is the study. Factors effecting bioavailability studies bodavula samba siva rao department of pharmacy, khammam college of pharmacy, khammam, andhra pradesh the goal of most oral dosage forms is to serve as a vehicle for the delivery of drugs to the blood stream for distribution to the site of action. Absorption, distribution, metabolism and excretion of drug. Factors affecting the distribution of electrolytes, water and. As the name implies, this is the stage when the drug is distributed to the bodys tissues.
World report 2017 united nations office on drugs and crime. In pharmacology, bioavailability is a subcategory of absorption and is the fraction of an administered dose of unchanged drug that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. Pdf drugs medicines are considered either the primary therapy or an adjunct to another. This booklet constitutes the second part of the world drug report 2017. Absorption is the study of how, once a drug is ingested, it moves from the stomach to the blood stream. The process of transferring a drug from the bloodstream to tissues is referred to as distribution. Drug factors lipid solubility of the drugs molecular weight of the drugs pka of drug 7. Other factors that influence mab distribution include diffusion, pinocytosis.
Stephen fitzpatrick, top judge favoured bali nine appeal, the. As the fluid passes through, water and nutrients are reabsorbed. It includes absorption, metabolism and food effect of drugs. 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. Pdf development of a rational scale to assess the harm of drugs. Several physiologic factors affect the distribution of a drug in older adults, including decreased body mass, reduced plasma albumin levels, and a less effective bloodbrain barrier. Patient acceptance of, response to, and compliance with, drug therapies may be influenced by religious restrictions and beliefs or cultural practices christian scientists. Pauline carter, and barbara hubbard for nursing care, payton king for. Pharmaceutic factors affecting drug bioavailability toxicology. In the kidney, most of the fluid in the blood is released into one end of the nephron. 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. Distribution patterns body water in various organs blood specific organ or tissue, e.
Other factors affecting drug absorption and distribution. 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. These factors may affect how the body absorbs the drug, how the body breaks down metabolizes and eliminates the drug, or what effects the drug has on the body. Many factors can affect a drug s absorption, distribution, metabolism, excretion, and ultimate effect. Adme absorption, distribution, metabolism and excretion. Factors governing the extent of drug absorbed from the mucosal surface include the concentration the active ingredient, the vehicle used for its delivery, contact time with the mucosal surface. The other major factor which determines the rate of drug distribution is blood perfusion. There are many recent advances and factors affecting bioavailability. Distribution which involves reversible transfer of a drug between compartments. Factors that affect the distribution of drugs in the body are. The speed with which drugs move in and out of the body varies widely among different people. Drug factors ph of the media regional blood flow drug bindingprotein tissue membranes 6.
Percentage distribution of people in treatment, by primary drug type, by region and. Full text full text is available as a scanned copy of the original print version. After a drug has been absorbed into the circulatory system. Drug distribution to tissues merck manuals professional edition. Director clinical pharmacology program october 1, 2015 office of clinical research training and medical. Various factors may cause adverse effect on the expected performance of distribution logistics system. The cyp enzymes play central roles in the metabolism of sms. 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. A perfusionrate limitation prevails when the tissue membranes present no barrier to distribution. Rate of distribution membrane permeability we have already covered some material about membrane permeability. Get a printable copy pdf file of the complete article 233k, or click on a page image below to browse page by page. When drugs given over prolonged period of time, upregulation of enzymes takes place. Olavi pelkonen, jorma ahokas encyclopedia of life support systems eolss can be improved by many methods e.
Other agerelated factors that may affect drug distribution include declining cardiac output, extreme changes in body weight, poor nutrition, dehydration. After a drug is absorbed into the bloodstream see drug absorption, it rapidly circulates through the body. Physicochemical parameters affecting drug action posted jun 29, 2014, 10. In addition to diffusion through these biological membranes, drugs in many extendedrelease systems must diffuse through a ratecontrolling polymeric membrane or matrix. Total body water is much greater in infants, fat content is also higher in infants and elderly, skeletal muscles are lesser in infants and in elderly, organ composition the bbb is poorly developed in. Understanding pkpd of mabs and factors that impact them, are essential to achieve these. Factors affecting drug action flashcards from mandy d. The usual adult dose of medication as listed in standard references, is based on the assumption that the adult weighs 150. Factors affecting drug action at texas womens university. Organs of high perfusion, protein binding, molecular size, and polarity. Physiological properties of drug pka, lipid solubility, etc.
In order to overcome 64 drugs and drug policy 03mosher. Factors affecting drug treatment compliance in patients with rheumatoid arthritis article pdf available in rheumatology international 278. Pdf factors affecting mechanism and kinetics of drug. As the name implies, this is the stage when the drug is distributed to the body s tissues. Because so many factors affect drug response, doctors must choose a drug appropriate for each person and must adjust the dose carefully.
Factors affecting bioavailability global events usa. After the pregnancy is over, the dosage is decreased back to normal levels. Drug distribution once in the blood, drugs are simultaneously distributed throughout the body and eliminated. Biological barriers throughout the body present challenges for drug delivery. 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. 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. Unlike the discovery and development of sm drugs, where the sciences and the. The report looks at issues of gender, marginalization, stig matization, violence. Which causes irreversible loss of drug from the body. Factors affecting drug absorption and distribution.
Impaired renal function may lead to a clinically significant accumulation of drugs eliminated by the kidneys, if more than 50% of the dose is normally excreted unchanged in the urine and the renal function is less than 50% of the. The drugs are present in free or bound form and different processes or mechanisms affect their. Differences in distribution pattern of a drug in different age groups are mainly due to differences in. The drug distribution is usually varied, and depends on several factors such as. Important physicochemical properties that influence drug distribution are molecular size, degree of ionization and partition coefficient. Pdf factors affecting drug treatment compliance in patients. Pharmaceutic factors affecting drug bioavailability. Inducing agents may increase the rate of their own metabolism as well as those of other unrelated drugs or foreign compounds table 3. Greater the lipid solubility, more is the distribution and vice versa. Distribution is generally uneven because of differences in blood perfusion, tissue binding eg, because of lipid content, regional ph, and permeability of cell membranes. The most important proteins in the blood that can affect the distribution of a drug include the plasma protein albumin, the alpha1 acid glycoprotein, and lipoproteins. This concept is related to multicompartmentalization. Drug distribution describes the process which transports a drug to its site of action, to other storage sites in the body, and to organs of metabolism and excretion. Organs of high perfusion, protein binding, molecular size.
Distribution is the study of how the blood stream carries a drug throughout the body. Factors affecting renal excretion of drugs include. Factors affecting distribution of drug tissue permeability of drug 1. Toxic effects might result when drug combinations act as enzyme inhibitors and inducers. A thorough knowledge ofthe chemical and physical stability of drugs and dosage forms is criticalin the development andevaluationofpharmaceuticals.
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