Absorption is used to described the journey of a drug travelling from the site of administration to. However, it was shown that the absorption rates in the small intestine tended to reach a ceiling at the high lipophilicity. Populationbased mechanistic prediction of oral drug absorption. The safety profile of the ingredients used in topical dosage forms and its evaluation is an issue of utmost importance. Stability of drugs and dosage forms rgm aisyahs blog.
A mechanistic approach to understanding the factors affecting drug absorption. Physiochemical factors affecting drug absorption free download as powerpoint presentation. The oral absorption of any chemical entity reflects a complex spectrum of events. These include age, species and strain, genetic or hereditary factors, sex, enzyme induction, and enzyme inhibition. Greater the lipid water solubility coefficient, more is the lipid solubility of the drug and greater is the absorption. Physicochemical factors affecting absorption authorstream presentation. Factors related to the physicochemical properties of the. Dissolution is rate limiting permeation is rate limiting step for lipophillic drugs. It includes absorption, metabolism and food effect of drugs. However, many drugs are given in solid dosage forms and therefore must dissolve before absorption can take place.
The absorption rates of the acylsalicylic acids were different in the intestinal regions. Phar 7633 chapter 11 physiological factors affecting oral. A mechanistic approach to understanding the factors. Some disorders like diabetic neuropathy causes gastric stasis and decrease the drug absorption. Physicochemical factors affecting absorption authorstream. 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. Factors affecting drug absorption free download as powerpoint presentation. Knowledge of the adme process and the factors influencing drug absorption and. To confirm this tendency, the absorption rates of acetaminophen and indomethacin were compared in the four intestinal regions. Drug absorption still continues after t max is reached, bodavula samba siva rao.
The bioavailability of drugs from oral formulations is influenced by many physiological factors including gastrointestinal fluid composition, ph. O factors affecting drug metabolism pharmaceutical chemistry. Introduction phpartition theory drug pka and gastrointestinal ph lipophilicity and drug absorption deviations from the ph partition theory a unifying hypothesis conclusion references drug absorption. Formulation factors affecting the dissolution rates of drugs from tablets and capsules, and thus influencing their absorption characteristics, include the surface area, polymorphic form, solvates and salt of the drug, the excipients and the process of manufacture. Director clinical pharmacology program september 30, 2010 office of clinical research training and medical education national institutes of health clinical center goals of drug absorption and bioavailability lecture factors affecting drug absorption estimation of.
Drug absorption is determined by the drugs physicochemical properties, formulation, and route of administration. Physicochemical and biopharmaceutical properties that. In each region, the absorption rate increased with the drug lipophilicity. Salt formation is frequently used to increase the solubility of a weak acid and base. The following table highlights some of these other factors. Pdf overview of factors affecting oral 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. Contents of the powerpoint on ph partition theory include. Absorption is the process by which drug molecules cross biological membranes. There are many recent advances and factors affecting bioavailability.
Factors affecting drug absorption flashcards quizlet. As discussed in chapter 19, the rate and extent of drug absorption are influenced by the physiological factors associated with the structure and function of the gastrointestinal tract. At t max, peak drug absorption occurs and the rate of drug absorption exactly equals the rate of drug elimination. Drug absorption is defined as the process of movement of unchanged drug from. Lipid water solubility coefficient is the ratio of dissolution of drug in lipid as compared to water. A free powerpoint ppt presentation displayed as a flash slide show on id. Ppt drug absorption powerpoint presentation free to. This chapter discusses the physicochemical properties of the drug and. The drug molecule combine with carrier protein and then it transferred drug to the other side of membrane, there it leaves the molecule and come back to normal situation or form. Factors affecting bioavailability global events usa. Due to drug treatment some time motility is increased or decreased.
Physico chemical factors affecting drug absorption vidyamitra. Absorption is a primary focus in drug development and medicinal chemistry, since the drug must be absorbed before any medicinal effects can take place. Physico chemical factors affecting drug absorption youtube. Drugdrug interactions memorable psychopharmacology duration. Pharmaceutic factors affecting drug bioavailability. There are many underlying chemical and physiological factors affecting the absorption of chemicals from the gi alimentary tract into the circulation. Factors affecting drug absorption small intestine stomach. Pharmacokinetic factors influencing variability in human. The excessively rapid movement of git impairs absorption. Solubility and permeability are considered as the major physicochemical factor that affect the rate and extent of oral drug absorption, moreover other physicochemical properties always show their. Factors influencing product bioavailability include drug solubility, permeability.
For most tissues, passive aqueous diffusion through channels. Developments in methods for measuring the intestinal. It also occurs by subcutaneous, intra muscular and transdermal routes of administration of drugs. Physiological factors affecting oral absorption physiological factors affecting oral absorption student objectives for this chapter after completing the material in this chapter each student should. A thorough knowledge ofthe chemical and physical stability of drugs and dosage forms is criticalin the development andevaluationofpharmaceuticals. The factors affecting absorption of drugs are related both to the drugs and to the body factors related to drugs. A suitable equilibrium between safety and efficacy is crucial before. Bioavailability physicochemical and dosage form factors. Physiological factors affecting absorption pharmatutor.
Moreover, the drugs pharmacokinetic profile can be easily and significantly changed by adjusting factors that affect absorption. Pdf impact of physiological, and biopharmaceutical. This article throws light upon the eight main physiological factors that affect the rate of drug absorption. The bioavailability of active drug can be varied from rapid and complete absorption to a slow, sustained rate of absorption or. Impact of physiological, physicochemical and biopharmaceutical factors in absorption and metabolism mechanisms on the drug oral bioavailability of rats and humans 480 expert opin. Physicalchemical factors affecting oral absorption drug dissolution so far we have looked at the transfer of drugs in solution in the gi tract, through a membrane, into solution in the blood. Drug solubility and dissolution rate the rate determining steps in absorption of orally administered drugs are. Department of pharmacology adapted from lectures of jeffrey l. Physicochemical factors drug solubility and dissolution rate solubility amount of a substance called the solute that dissolves in a unit volume of a liquid substance called the solvent to form a saturated solution under specified conditions of temperature and pressure. 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. Pharmacokinetic factors influencing variability in human drug response. Principles of gastrointestinal drug absorption part 5. Each route of drug application presents special biopharmaceutic consideration in designing a drug product.
Factors affecting gastrointestinal absorption of drugs. Physiological factors and drug absorption pharmacokinetics. These solubility differences may alter drug product in vivo dissolution, hence affecting oral drug absorption. 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. Drug absorption depends on the lipid solubility of the drug, its formulation and the route of administration. For instance,a drug administered orally in tablet or capsule form it has to undergo disintegration and deaggregation rapidly. 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. The solubility enhancement of a drug substance by salt formation is related to several factors including the thermodynamically. Factors effecting bioavailability studies bodavula samba siva rao department of pharmacy, khammam college of pharmacy, khammam, andhra pradesh. A mechanistic approach to understanding the factors affecting drug. Other factors affecting drug absorption and distribution. After reading this article you will learn about the pharmaceutic factors affecting drug bioavailability.
Drug absorption, drug distribution, drug dissolution, drug solubility introduction. Pharmaceutical factors a chemical factors b physicochemical properties of drug substances 1. 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. However, the absorptive process does not occur during direct injection of drug by intravenous or intra arterial injection. Learn vocabulary, terms, and more with flashcards, games, and other study tools. It is usually associated with oral drugs and their absorption through the git. Phar 7633 chapter 12 physicalchemical factors affecting. Dosage forms eg, tablets, capsules, solutions, consisting of the drug plus other ingredients, are formulated to be given by various routes eg, oral, buccal, sublingual, rectal, parenteral, topical, inhalational.
Physicochemical properties effect on absorption of drugs. Mechanism of absorption of drug by four ways the drug can be migrated. The rate and extent of absorption after a particular route of administration are dependent on many drug and patient factors. This chapter discusses the passive diffusion of an orally absorbed drug molecule. When the standard consists of intravenously administered drug, this is known as relative bioavailability. Other factors such as dose and drug stability in the intestinal medium, which can significantly impact oral absorption, must also be considered.
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