The absorption rates of the acylsalicylic acids were different in the intestinal regions. To understand the physiological factors which affect the oral absorption of drug products physiological factors. Greater the lipid water solubility coefficient, more is the lipid solubility of the drug and greater is the absorption. Sep 19, 2014 3 factors affecting drug absorption physicochemical factors. List the major factors that affect drug absorption from oral and nonoral routes of. For example, highfiber foods and calcium supplements may bind with a drug and prevent it from being absorbed. Solubility as a limiting factor to drug absorption. Some disorders like diabetic neuropathy causes gastric stasis and decrease the drug 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. Pharmacists must also understand the relationship of drug dosage to therapeutic efficacy. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The approach used would enable a cosmetic chemist to predict the relative degree of drug absorption through skin from the physicochemical constants of series of compounds and the absorption data. Properties pdf win32 programming is required to give optimal absorption.
A seminar on physicochemical properties affecting drug absorption. Molecular size and shape, aciditybasicity, lipophillicity and steric and electronic characteristic of a drug influence its interaction with the active site of enzyme. Feb 08, 2018 overall scheme of drug absorption, distribution, and elimination no matter how the drug is given other than i. Solubility and permeability are considered as the major physicochemical factor that affect the rate and extent of oral drug absorption, moreover other. Drug absorption, drug distribution, drug dissolution, drug solubility introduction. Ensuring a sufficient compound concentration in solution at the primary site of absorption is a requirement for successful oral drug absorption.
The purpose was to explore the relationship between precipitated solid form and inherent physicochemical properties of the drug. Physicochemical parameters affecting drug action dr. Pharmaceutical factors a chemical factors b physicochemical properties of drug substances 1. For most drugs, two to fivefold differences in the rate or extent of gastrointestinal absorption can occur, depending on the dosage form. Poor oral bioavailability affects drug performance and leads to high intra and interpatient variability. Factors influencing product bioavailability include drug sol ubility, permeability. For instance,a drug administered orally in tablet or capsule form it has to undergo disintegration and deaggregation rapidly. Factors affecting drug metabolism drug metabolism metabolism.
This chapter discusses the physicochemical properties of the drug and dosage form factors that influence bioavailability. Considerations in the design of a drug product to deliver the active drug with the desired bioavailability characteristics and therapeutic objectives include 1 the physicochemical properties of the drug molecule, 2 the type of drug product eg, tablet, capsule, transdermal delivery system, topical ointment, parenteral solution, 3 the. Physicochemical properties of oral drug candidates in the discovery and exploratory. 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. However, it was shown that the absorption rates in the small intestine tended to reach a ceiling at the high lipophilicity. Although some absorption of acids takes place in the stomach, absorption also occurs in small intestine due to. Factors affecting drug absorption linkedin slideshare. Factors related to the physicochemical properties of the drug. Physicochemical properties of drugs pharmaceutical press. Molecular and physicochemical properties impacting.
Drug solubility solubility of drug plays a prime role in controlling its dissolution from dosage form. Drug absorption drugs merck manuals consumer version. We classify the physicochemical characteristics of a drug molecule or particle into those that are solely related to chemical structures and those that are related to physical shape eg, crystalline forms. In this study we investigated lipolysistriggered supersaturation and precipitation of a set of model compounds formulated in lipidbased formulations lbfs. 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. Due to drug treatment some time motility is increased or decreased. The factors affecting absorption of drugs are related both to the drugs and to the body. Factors affecting fa are the characteristics of the formulation drug. Factors affecting dissolution rate divided into five classes a.
Physiological factors affecting absorption pharmatutor. Chemical factors of drugs affecting absorption, distribution, and excretion heinrich keberle chemical research laboratories, pharmaceutical division, ciba limited, basle, switzerland. Physicochemical factors affecting skin absorption request pdf. Molecular weight is an important physicochemical parameter that should be considered when optimizing intestinal permeability.
Eight drugs were studied after formulation in three lbfs, representing lipidrich extensively digestible. Aqueous solubility of drug is a major factor that determines its dissolution rate. Physicochemical factors affecting drug absorption i. Physicochemical factors affecting absorption authorstream. Physicochemical factors affecting absorption authorstream presentation. Physiologically, a drugs absorption is enhanced if there is a large surface area available for absorption e. A mechanistic approach to understanding the factors affecting. Download this books into available format unlimited. Factors influencing product bioavailability include drug solubility, permeability. Pdf nasal drug delivery systemfactors affecting and. 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. Biopharmaceutics links the physical and chemical properties of the drug and the drug product to their performance, in vivo. The objective of this paper is to focus on the rationality of drug selection based on pharmacokinetic parameters and physicochemical properties of the drug. Some basic thermodynamic concepts will be introduced, particularly that of thermodynamic activity, an important parameter in determining drug potency.
In this chapter we examine some of the important physicochemical properties of drugs in aqueous solution which are of relevance to such liquid dosage forms as injections, solutions, and eye drops. Physiochemical factors such as solubility, crystallinity, molecular weight may 29, 2018 for the love of physics walter lewin may 16, 2011 duration. Lipid water solubility coefficient is the ratio of dissolution of drug in lipid as compared to water. There are various factors which control of absorption through the oral route and thus affect the. Regarding the physicochemical factors affecting the absorption of drugs. Physicochemical and biopharmaceutical properties that. Physicochemical properties of drugs 61 applying knowledge of the pka and an appreciation of the extent to which drugs ionise in solution. Jun 25, 2019 the importance of the physicochemical properties on the dissolution of a drug substance into the dissolution medium is best illustrated by 3. The influence of physicochemical properties on adme. Impact of drug physicochemical properties on lipolysis. Deductions of this type form the basis ofmedicinal chemistry, the science of rational drug design. Biopharmaceutics is the study of the physicochemical properties of the drug and the drug product, in vitro, on the bioavailability of the drug, in vivo, to produce a desired therapeutic effect. Just as the absorption and distribution of a drug are influenced by its physicochemical properties so is its interaction with the drug metabolising enzymes.
Other factors that also impact drug absorption include the following. Bioavailability physicochemical and dosage form factors. In each region, the absorption rate increased with the drug lipophilicity. 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. Laxatives and diarrhea, which speed up the passage of substances through the digestive tract, may reduce drug absorption.
Absorption ionisation in man, stomach is ph 2 and small intestine ph 6 weak acids unionised form is more prevalent in the stomach. Drug absorption is determined by the drugs physicochemical properties, formulation, and route of administration. Despite the fact that these three equations are derived from different diffusion mechanisms, they clearly show that the dissolution rate depends on the solubility and surface area of a drug. Pdf overview of factors affecting oral drug absorption. Factors affecting gastrointestinal absorption of drugs. Considering the structure of membranes transport processes b.
Over 10 million scientific documents at your fingertips. The bioavailability of active drug can be varied from rapid and complete absorption to a slow, sustained rate of absorption or. Pharmaceutic factors affecting drug bioavailability toxicology. The oral absorption of any chemical entity reflects a complex spectrum of events. The excessively rapid movement of git impairs absorption. Certain changes within each of the four categories will produce uniform or predictable changes in drug absorption. Considerations in the design of a drug product to deliver the active drug with the desired bioavailability characteristics and therapeutic objectives include 1 the physicochemical properties of the drug molecule, 2 the type of drug product eg, tablet, capsule, transdermal delivery system, topical ointment, parenteral solution, 3 the nature of the excipients in the drug product, 4 the.
Physiological factors affecting oral absorption objective. A primary concern in biopharmaceutics is the bioavailability of drugs. Bioavailability of a drug depends on physicochemical properties of the drug and. Each route of drug application presents special biopharmaceutic consideration in designing a drug product. Request pdf a mechanistic approach to understanding the factors affecting drug absorption. The biopharmaceutical classification system bcs was introduced in early 90. Biological and physicochemical factors affecting bioavailability. Nasal drug delivery system factors affecting a nd applications current drug therapy, 2007, vol. Physicochemical and pharmacokinetic parameters in drug.
Populationbased mechanistic prediction of oral drug absorption. In oral drug absorption, prediciton and assessment. Phenols another commonly encountered acidic functional group found in drug molecules is phenol, or. Permeation of the drug across the membrane, gi transit, site specificity, firstpass. Neonatal absorptionintramuscular physicochemical and physiologic factors affect rate drug ph, lipophilicity blood flow, total surface area of muscle at injection site rate of absorption may be lower extent of absorption may be higher secondary to higher density of skeletal muscle capillaries compared to older children and. A mechanistic approach to understanding the factors. Minimum aqueous solubility of 1% is required to avoid potential solubility limited absorption problems. Absorption of drugs distribution of drugsbiotransformation. Physicochemical parameters affecting drug action posted jun 29, 2014, 10. Physiologic factors related to drug absorption applied. Food, other drugs, and digestive disorders can affect drug absorption and bioavailability.
Physicochemical properties effect on absorption of drugs slideshare. A mechanistic approach to understanding the factors affecting drug absorption. Factors that influence drug absorption through oral route are. These two characteristics, rate and completeness of absorption, comprise bioavailability. The systemic absorption of a drug is dependent on 1 the physicochemical. 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. 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.
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