Compare the roles of passive diffusion and carriermediated transport in drug absorption. A need for adme characterization in drug discovery and development jay tibbittsa, david canter b, ryan graff, alison smithb, and leslie a. It has been shown that the dosageexcretion patterns of vitamins differ. Oral administration of a drug with food generally reduces its absorption. Factors affecting drug metabolism online lecture lecturio. Oral drug bioavailability can also be markedly influenced by physiological factors, such as gastrointestinal ph, gastric emptying, small intestinal transit time, bile. Factors influencing drug response intrinsic genetic absorption, distribution, metabolism, excretion genetic conditions genetic polymorphism of drugmetabolizing enzymes height race receptor. Discuss the factors which determine the bioavailability of a drug. Drugs are absorbed from the site of administration into the systemic circulation, where they may interact with the proteins. Pharmaceutical factors a chemical factors b physicochemical properties. With oral administration, several factors affect the absorption of a drug. Factors which influence gastrointestinal drug absorption. Factors influencing drug absorption powerpoint presentation. Drug absorption is a pharmacokinetic parameter that refers to the way a drug.
Factors influencing gi absorption of drug free download as powerpoint presentation. Several factors can affect the absorption of a drug. Factors affecting bioavailability learn with flashcards, games, and more for free. Pharmacokinetic part 01 absorption and factors affecting.
Drug distribution across the placenta is a special case and considered separately. Some factors affecting the absorption of vitamins the. Factors influencing the design and performance of oral. Pharmacokinetic factors influencing variability in human drug. Othe af90t is a fully automatic capsulefilling machine that can fill a large variety of powder formulations into hard gelatin capsules. A mechanistic approach to understanding the factors. Factors influencing gi absorption of drug tablet pharmacy. Although the solid solution is an attractive approach to increase drug absorption, only one drug, griseofulvin, is currently marketed in this form. Drug absorption depends on the lipid solubility of the drug, its formulation and the route of administration. The rate and extent of absorption after a particular route of administration are dependent on many drug and patient factors. Jan 24, 2019 the chemical composition of a drug, as well as the environment into which a drug is placed, work together to determine the rate and extent of drug absorption. Injection intravenous injection is the most direct route of administration, providing a patient with drug that is immediately available for distribution to its effect sites. Some drugs are irritating and should be administered with meals to reduce adverse effects. Hoener and others published factors influencing drug absorption and drug availability find, read and cite all the.
Pharmacokinetic is a quantitative study of drugs in the body absorption, distribution, metabolism and excretion of the law. Factors influencing gi bioavailabilityphysicochemical factors. Drugdrug interactions can be classified in terms of indirect effects by one drug on gastrointestinal tract physiology influencing the absorption of other drugs, or direct interactions involving altered ph, adsorption, absorption, or chelation. Factors affecting drug absorption and distribution. Physiological factors and drug absorption pharmacokinetics. Rang and dale basically brushes this aside by saying that the mechanism of drug absorption is the same as for other epithelial barriers, namely passive transfer at a rate determined by the ionisation and lipid solubility of the drug molecules.
Many factors, most of which are not fully understood, are involved in vitamin absorption. Explain how bioavailability can impact drug response and product selection. Amount of drug that exists in unionized form and in ionized form is a function of pka of drug and ph of the fluid at the absorption site, and it can be determined by handersonhasselbach equation. Pharmacokinetics defines what the body does to the drug. This article throws light upon the eight main physiological factors that affect the rate of drug absorption. The factors affecting absorption of drugs are related both to the drugs and to the body factors related to drugs. Some drugs are not affected by food, while the absorption of a third group of drugs is enhanced by food bile secretion by liver in response to food in gi tract increases drug absorption. The passage of drugs across cell membranes is a key part of most pharmacokinetic processes. Drug drug interactions can be classified in terms of indirect effects by one drug on gastrointestinal tract physiology influencing the absorption of other drugs, or direct interactions involving altered ph, adsorption, absorption, or chelation. Jun 19, 2019 drug absorption is a pharmacokinetic parameter that refers to the way a drug is absorbed from a pharmaceutical formulation into the bloodstream. Factors affecting drug absorption and distribution anaesthesia and. The volume of injection, osmolality of the solution, lipid solubility and degree of ionization influence absorption. Pharmacokinetics is the study of a drug absorption, distribution, metabolism and elimination from the body. Factors that increase gastric emptying will usually increase the rate of absorption of a drug.
It is well recognised that the clinical response to drug administration varies widely between individuals and that most of this variability is pharmacokinetic in origin. Factors affecting drug absorption and distribution sciencedirect. Lipid water solubility coefficient is the ratio of dissolution of drug in lipid as compared to water. Overview of factors affecting oral drug absorption naining song a,b, shaoy u zhang b, changxiao liu a a tianjin state key laboratory of pharmacokinetics and pharmaco dynamics, tianjin inst.
Certain changes within each of the four categories will produce uniform or predictable changes in drug. Factors affecting drug absorption and distribution anaesthesia. Factors affecting gastrointestinal absorption of drugs. The use of mathematical principles and methods to explain the plasma concentration with time changes in a discipline. Factors influencing drug absorption and drug availability. Variability of drug response is also a consequence of a variety of drug interactions.
Drug absorption is a pharmacokinetic parameter that refers to the way a drug is absorbed from a pharmaceutical formulation into the bloodstream. Specifically, this chapter deals with gastrointestinal absorption which seems to be important, not only because it is a common route of drug administration but also because it has appeared at least once in the written. Factors influencing product bioavailability include drug solubility, permeability, and the rate of in vivo dissolution. The passage of drugs across cell membranes is a key part of. Factors affecting surface drug absorption many factors affect how the application of a particular drug will be absorbed by the skin surface. Membrane structure and function the cell membrane is a semipermeable lipoid sieve containing numerous aqueous channels, as well as a variety of specialized carrier molecules. Physiological factors affecting absorption pharmatutor. Fulltext pdf drugs used to treat joint and muscle disease. Subcutaneous injection some drugs, notably insulin, are routinely administered sc. It should not be assumed that the im route is as reliable as the iv route. How a drug works and what happens to it upon entering the body are important factors in drug design, in order to ensure optimal action in the desired amount of time. Aug 14, 2017 there are four factors that will influence the pharmacokinetic drugs test. Interactions affecting drug absorption springerlink.
Several factors can affect the absorption of a drug into the body. Pharmacists must also understand the relationship of drug dosage to therapeutic efficacy. The chemical composition of a drug, as well as the environment into which a drug is placed, work together to determine the rate and extent of. Factors affecting pharmacokinetics of drugs medicilon inc. These include mode of administration, pharmaceutical form and size of the dose as well as site of absorption of the vitamin. The placental membrane is a lipid barrier that is less selective than the bloodbrain barrier, allowing the passage of lipidsoluble drugs more easily than watersoluble drugs.
Factors influencing the design and performance of 585 considering the ph partition hypothesis, the importance of equations 2 and 3 relative to drug absorption is evident. Key factors influencing adme properties of therapeutic. Already at this stage, there are several individual factors that can affect drug response, such as the patients age, gastric ph, a highfat diet, cardiovascular or digestive diseases, rate of gastric emptying and gastric motility. A mechanistic approach to understanding the factors affecting. Learn vocabulary, terms, and more with flashcards, games, and other study tools. In this regard, the biopharmaceutics classification system has proven to be an important tool for predicting compounds likely to be associated with bioavailability problems. Contents introduction definition factors affecting absorption conclusion references 3. If any drug is undergoing first pass metabolism and it may be degraded by liver or by the enzyme present in the gut, the bioavailability of the drug is decreased. Drugs such as neostigmine and gentamicin, which are highly ionised, are poorly absorbed. The ph partition hypothesis simply states that the unionized form in the stomach ph. For most tissues, passive aqueous diffusion through channels. If more is the cycling of drugs, then more absorption of drugs.
Pharmacokinetics definition, principles, factors affecting. Factors modifying drug effect and dosage pharmacodynamics. The pharmacokinetic properties determine the onset, intensity, and the duration of drug action in body. Study 74 terms factors affecting bioavailability flashcards. Hoener and others published factors influencing drug absorption and drug availability find, read and cite all the research you need on researchgate. There are four factors that will influence the pharmacokinetic drugs test. The pharmacokinetic properties of a drug comprise the relationship between its absorption, distribution and inactivation. This chapter answers parts from section bii of the 2017 cicm primary syllabus, which expects the exam candidate to describe absorption and factors that will influence it. Describe two types of drug interaction and explain how. The absolute bioavailability of a drug, when administered by an extravascular route, is usually less than one i. Certain changes within each of the four categories will produce uniform or predictable changes in drug absorption. Factors affecting drug absorption linkedin slideshare.
Pharmacokinetic factors influencing variability in human. Factors influencing drug absorption and drug availability request. Solubility lipophilicity degree of ionization pka complexation. Pdf overview of factors affecting oral drug absorption. In order to develop a drug product that elicits the desired therapeutic objective, the pharmaceutical scientist must have a thorough understanding of the biopharmaceutic properties of the drug and drug product and the physiologic and pathologic factors affecting drug absorption from the application site. A drug injected intravascularly directly enters the systemic circulation and exerts its pharmacological effects.
Scribd is the worlds largest social reading and publishing site. The factors affecting absorption of drugs are related both to the drugs and to the body. Greater the lipid water solubility coefficient, more is the lipid solubility of the drug and greater is the absorption. Factors influencing drug response intrinsic genetic absorption, distribution, metabolism, excretion genetic conditions genetic polymorphism of drug metabolizing enzymes height race receptor. In general, variability arises because of interindividual differences in rates of drug absorption, drug distribution and elimination, either by metabolism or excretion. Pharmacokinetic factors influencing variability in human drug response. List two physiologic factors that can alter each of the processes of absorption, distribution, and excretion. Pharmaceutical factors a chemical factors b physicochemical properties of drug substances 1.
1190 1153 1092 5 314 1044 1021 1414 1101 1296 31 972 753 175 642 227 955 608 58 970 910 1442 304 881 1059 427 1090 172