Theory of drug activity and drug receptor interaction pdf

Mechanisms of drug interactions introduction the risk of dying from a drugrelated incident now exceeds the risk of dying in a traffic accident. It is defined as the affinity of one for the other. Drug receptor theory also furnishes the tools for quantifying the activity of drugs in a systemindependent manner, essential because drugs are almost always studied in test systems somewhat. Because this new class of drugs is extensively used, serious drugdrug interactions are an increasing risk. A molecule is a small chemical element that is made up of two or more atoms held together by chemical bonds. Receptors vary greatly in structure so a specific chemical structure is required for the receptor site and a.

The strength of the reversible interaction between a drug and its receptor. This statistic is a wide net and includes intentional overdose and illicit drug use, as well as adverse drug reac. A large category of them exerts their physiologic effects by binding with naturally selective receptor s and thus making the drug receptor interaction a widely studied subject, considering. In 2008 the most recent data available, 36,500 drug related deaths were reported. A drug that binds to a receptor and produces a biological response is an agonist. A drugs ability to affect a given receptor is related to the drugs affinity probability of the drug occupying a receptor at any given instant and intrinsic efficacy intrinsic activitydegree to which a ligand activates receptors and leads to cellular response. Explain the concept of drug action with respect to receptor theory, enzyme interactions and physicochemical interactions. This type of bonding is the strongest form of bond that can be formed between a ligand and a receptor. The drug receptor interaction is usually reversible. To find the interaction between drug molecule and receptor by performing docking studies. As noted above, drug receptor interaction can generally be defined as specific, doserelated and saturable. An important field of study in pharmacology comprises the investigation of drug target interaction kinetics.

Drugdrug interactions with tyrosinekinase inhibitors. A drug that interacts with a single type of receptor that is expressed on only a limited number of differentiated cells will exhibit high specificity. An important field of study in pharmacology comprises the investigation of drugtarget interaction kinetics. Occupancy theory rests on the concept that the proportion of occupied receptors is related to the effect of the drug eg. The interaction of the ligand at its binding site on the. Intrinsic activity ia and efficacy refer to the relative ability of a drugreceptor complex to produce a maximum functional response. The bond formed is so very strong that detachment of the ligand is very hard and nonspontaneous. Pdf drugs by definition, are characterized as those agents that can bring a change in. If a drug does not dissociate due to a very tight binding such as a covalent bond, the effect continues to be produced as long as the receptordrug complex remains intact. Drugs with short duration of action generally have weaker. What are the historical origins of the receptor concept. Pdf in presentday pharmacology and medicine, it is usually taken for granted. Drugreceptor interactions involve all known types of bond. The driving force for drugreceptor interaction is the low energy state of the drugreceptor complex.

Theories of drug receptor interaction free download as powerpoint presentation. Thus, an agonist has the properties of affinity and intrinsic activity. A common example of an antagonistic drug interaction is the effect of concurrent zidovudine and stavu2b4 202 inducers inhibitors substrates 1a2 ritonavir, rifampin. A drugreceptor interaction occurs where a drug binds to a specific ligand for an endogenous regulatory substance. The driving force for the drug receptor interaction can be considered as a low energy state of the drug receptor complex, where kon is the rate constant for formation of the drug receptor complex, which depends on the concentration of the drug and the receptor koff is the rate constant for breakdown of the complex, which depends on the. The central dogma of receptor pharmacology is that a drug effect is directly proportional to the number of receptors that are occupied. Classification of drugs based on drugreceptor interactions. Molecular orbital theory in drug research is a 12chapter text that emerged from a series of lectures presented to graduate students in medicinal chemistry at the university of michigan.

Classification of drugs based on drug receptor interactions. The interaction between the drug d and receptor r is governed by the law of mass action. Molecular pharmacology, structureactivity relations, gastric acid secretion, pp. Theories of drug receptor interaction receptor antagonist. Kinetics of drugreceptor interaction springer for research. Feb 25, 2018 theories of drug receptor interaction 1. An antagonistic effect results when a drugs pharmacologic effect is reduced due to concurrent therapy. Michael j curtis, pharmacologic analysis of drugreceptor interaction 2nd edition. The action of the benzodiazepines on the gaba receptor chapter 4 may be of this type. But it can be 0 if intrinsic receptor activity exists b threshold dose drug dose or below which there is no appreciable in receptor activity with agonist binding important to note this hyperbolic relationship is the result of the dynamics of drugreceptor interaction see law of mass action below. Pharmacodynamics is the study of the biochemical and physiologic effects of drugs and their mechanisms of action on the body or on microorganisms and other parasites within or on the body. The interaction of histaminomimetic compounds and of competitive antagonists of histamine with the histamine receptor.

Drug receptor interactions receptor antagonist receptor. Drugs interact with receptors in a reversible manner to produce a change in the state of the receptor, which is then translated into a physiological effect. Allows one to determine a rough estimate of an unlabeled ligands affinity for a receptor. Molecular orbital theory in drug research 1st edition. This molecular interaction with the receptor can be modeled mathematically and obeys the law of mass action. Pharmacologic analysis of drugreceptor interaction 2nd. Balis, in principles of clinical pharmacology second edition, 2007. Intrinsic activity ia and efficacy refer to the relative ability of a drug receptor complex to produce a maximum functional response. Thus, assessing both the lifetime of the drug on its receptor i. Quoting from kenakian 2008, receptor occupancy theory describes the quantitative relationships between drug concentrations and the responses that result from the interaction of those drugs with receptors. Activity and molecular composition in the case of pharmacology, the fundamental postulate of chemistry reduces to the proposition that. These characteristics of a drug at a receptor are described by k d and ed 50 and can be obtained from ligand binding and doseresponse curves. Frontiers exploring drugreceptor interaction kinetics. As the drug concentration is increased, a progressively higher fraction of available receptors will become occupied by drug until all available receptors become bound.

Drug receptor theory also furnishes the tools for quantifying the activity of drugs in a system. The drugreceptor concept of drug action and the receptor occupation theory describe a graded doseeffect relationship, in which the responding system is capable of showing a progressively increasing effect with increasing dose or drug concentration. Theories for relationship between drug receptor interaction. A minimum three point attachment of a drug to a receptor site is required. But it can be 0 if intrinsic receptor activity exists b threshold dose drug dose or below which there is no appreciable in receptor activity with agonist binding important to note this hyperbolic relationship is the result of the dynamics of drugreceptor interaction see. The term drug action is used to describe the method by which the drug influences a cell and the term drug effect or response is a. Drug action and pharmacodynamics pharmacology veterinary. Theories of drug activity last updated on tue, 03 sep 2019 how drugs act although there is no single uniform theory that can explain the activity of drugs, several theories have been advanced over the years in attempts to elucidate drug action. This must be distinguished from the affinity, which is a measure of the ability of the drug to bind to its molecular target, and the ec 50, which is a measure of the potency of the drug and which is proportional to both efficacy and affinity. When a drug is modelled on a hormone or a neurotransmitter, there is usually a need to develop selectivity so that the drug only interacts with specific receptors and not with all the receptors that are sensitive to a particular neurotransmitter.

In the past decade, many tyrosinekinase inhibitors have been introduced in oncology and haematooncology. A drug receptor interaction occurs where a drug binds to a specific ligand for an endogenous regulatory substance. A drug that binds to a receptor but does not initiate a cellular response is an antagonist. Drug receptor interactions an overview sciencedirect. A drug interaction is a change in the action or side effects of a drug caused by concomitant administration with a food, beverage, supplement, or another drug. When the ligand approaches the receptor in an appropriate distance, a bond is formed, and then the drug action happens. Mechanisms of drug interactions introduction the risk of dying from a drug related incident now exceeds the risk of dying in a traffic accident. A theory of drug action is developed on the assumption that excitation by a stimulant drug is proportional to the rate of drugreceptor combination, rather than. Ppt receptor theory powerpoint presentation free to view. Drugreceptor interactions clinical pharmacology msd. A drugs affinity and activity are determined by its chemical structure. This stability is commonly measured by how difficult is for the complex to dissociate, which is measured by its kd, the dissociation constant for the drug receptor complex at. General theory of drugreceptor interactions springerlink.

Receptor theory of drug action deranged physiology. The theoretical basis for using dipole moment as a free. Drug it is a natural or synthetic substances which has a physiological effects when administered into the body. The drugreceptor interaction implies a mutual molding of drug and receptor like a lock and its matching key. The receptor theory is as important and basic to pharmacology as the atomic theory is to physical sciences. The biological activity is related to the drug affinity for the receptor, i. A theory of drug action based on the rate of drugreceptor combination. For example, one drug may alter the pharmacokinetics of another. The biological activity of drug is related to its affinity for the receptor. The driving force for the drugreceptor interaction can be considered as a low energy state of the drugreceptor complex, where kon is the rate constant for formation of the drugreceptor complex, which depends on the concentration of the drug and the receptor koff is the rate constant for breakdown of the complex, which depends on the.

It covers the basic principles of how new drugs are discovered with. Dissociation constant of the drugreceptor complex gives an idea a bout how potent is the drug. An illustration of the relationship between drug concentration and receptor occupancy by drug is shown in. Receptor theory was propounded by alfred joseph clark, a theory of drug action based on occupation of receptors by specific drugs and the cellular function can be altered by interaction of the receptors with the drugs.

Drug receptor interactions an overview sciencedirect topics. The classical interaction theory dictates that receptors occupation is directly. Receptor theory is the application of receptor models to explain drug behavior. It considers both drug action, which refers to the initial consequence of a drugreceptor interaction, and drug effect, which refers to the subsequent effects.

Copeland dept of pharmacology october 17, 2008 concept of specific drug receptors most drugs combine with specific sites on macromolecules e. Pharmacological receptor models preceded accurate knowledge of receptors by many years. The drug receptor interaction implies a mutual molding of drug and receptor like a lock and its matching key. Drugs can exert their pharmacological action in two different ways. The interaction of human haemoglobin with allosteric. Agonist, antagonist and theories of drug receptor interaction presented by abhishek ghara 1st year m. J receptor theory and structureaction relationships. Molecular pharmacology, structure activity relations, gastric acid secretion, pp. The biological activity of drug is related to its affinity for the receptor, i. Theories of drug activity how drugs act drug times. Over 300 group dipole moments for aromatic substituents were compiled using the dipole moments of monosubstituted benzene derivatives. Binding of drug to receptor is essentially the same as drug to enzyme as defined by the michelismenten equation. Clarkes receptor occupation theory the occupancy model was the first model put forward by clark to explain the activity of drugs at receptors quantified the relationship between drug concentration and observed effect.