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 there are many causes of drug interactions. Under such conditions, regardless of the assay employed, ligand l binding to its receptor r at equilibrium is. Drugs act on the cell membrane by physical andor chemical interactions. 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. Amged sirelkhatim 2 when a drug interacts with a receptor, a. The driving force for drug receptor interaction is the low energy state of the drug receptor complex.
Some of these interactions can occur even at moderate drinking levels and result in adverse health effects for the drinker. Alternatively, drug interactions may result from competition for a single receptor or signaling pathway. Dissociation constant of the drug receptor complex gives an idea a bout how potent is the drug. We show the role of the conformational component of the entropy in the complex formation between a substance and a specific neuroreceptor, using mcholinolytics and ligands of. The binding of a drug to receptor depends on types of chemical bounds that can be established between drug and receptor. There are spare receptors, only very small amounts of drugs are required for maximum effect. Receptors are macromolecules involved in chemical signaling between and within cells. This is usually through specific drug receptor sites known to be located on the membrane. To firmly grasp the concepts of how effects, both desired and. Pharmacological receptor models preceded accurate knowledge of receptors by many years. Mohamed, faculty of pharmacy, university of khartoum 2014 4. A drug that binds to a receptor but does not initiate a cellular response is an antagonist. 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.
If you conceptualize drug receptor interactions as a lock and key model, agonists are keys that fit into a lock receptor and open activate them, whereas antagonists fit into the lock and jam the mechanism. A neurotransmitter has a specific shape to fit into a receptor site and cause a pharmacological response such as a nerve impulse being sent. For example, one drug may alter the pharmacokinetics of another. Drug discovery to drug development pipeline preexisting target literature target. Drug interactions between ccr5 antagonist and other drugs the information in the brief version is excerpted directly from the fulltext guidelines. The medicinal chemistry course adme adsorption, distribution, metabolism and excretion of drugs drug receptor interactions development of drugs screening techniques combinatorial chemistry d. The specific binding site on a receptor may be identified and studied.
Some drug interactions can be understood by looking at the properties of a single compound. Drug interactions of antidiabetics part 1 diabetic patients take insulin andor other oral hypoglycemic and antihyperglycemic drugs to control their blood sugar levels. Interaction between the drug and the biologic receptor would be expected to take place by utilizing the same bonding forces involved as thosewhensimple moleculesinteract. The vast majority of drugs show a remarkably high correlation of structure and specificity to produce pharmacological effects. Occupancy theory rests on the concept that the proportion of occupied receptors is related to the effect of the drug eg. Thus, an agonist has the properties of affinity and intrinsic activity. Mechanisms of pharmacodynamic drugdrug interactions. Ppt drugreceptor interactions powerpoint presentation. Law of mass action when a drug d combines with a receptor r, it does so at a rate which is dependent on the concentration of the drug and the concentration. Drugs, aging, genetic mutations, and disorders can increase upregulate or decrease downregulate the number and binding affinity of receptors. The neurotransmitter is similar to a substrate in an enzyme interaction.
Drug receptor interactions an overview sciencedirect. Mechanism of drug action drug receptor interactions howmed. The brief version is a compilation of the tables and boxed recommendations. For example, if we know how cannabidiol cbd, a nonintoxicating component of cannabis, inhibits drug metabolizing enzymes, then we can foresee certain interactions. For example, clonidine downregulates alpha 2 receptors. Baseline receptor density and the efficiency of stimulusresponse mechanisms vary from tissue to tissue. 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. 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 sequel to this action. Clinical implications of drugdrug interactions with p2y12. To elaborate on these is the objective of this chapter. Activated receptors directly or indirectly regulate cellular biochemical processes eg, ion conductance, protein phosphorylation, dna transcription, enzymatic activity.
Receptor theory of drug action deranged physiology. When receptor sensitivity changes, the same concentration of a drug will produce a greater or lesser physiological response. These biomolecules could be proteins, nucleic acids, receptors, enzymes, hormones, ion channels etc. Can glide retrieve known active compounds from a decoy set. General theory of drugreceptor interactions springerlink.
Copeland dept of pharmacology october 17, 2008 concept of specific drug receptors most drugs combine with specific sites on macromolecules e. However, the latter process does not last too long because at some point the receptor drug complex is degraded and eliminated, and a new free receptor is synthesized. The bond formed is so very strong that detachment of the ligand is very hard and nonspontaneous. Most drug interactions are not serious, but because a few are, it is important to understand the possible outcome before you take your medications. This molecular interaction with the receptor can be modeled mathematically and obeys the law of mass action. I pharmacodynamics in pharmacology terry kenakin encyclopedia of life support systems eolss pharmacodynamics in pharmacology terry kenakin glaxosmithkline research and development, usa keywords. Experimental evidence indicates that drugs interact with receptor sites localized in macromolecules which have proteinlike properties and specific three dimensional shapes. A large category of them exerts their physiologic effects by binding with naturally selective receptor s and thus making the drugreceptor interaction a widely studied subject, considering particularly the complex intracellular biochemistry, pharmacology and energetics involved in the entire event. Drug receptor interactions abstract in presentday pharmacology and medicine, it is usually taken for granted that cells contain a host of highly specific receptors. Here we will be focussing on two of the main biomolecules when it comes to drug target interaction, enzymes and receptors. The biological activity is related to the drug affinity for the receptor, i. A drug that binds to a receptor and produces a biological response is an agonist. The simplest model of drugreceptor or more generally protein interaction is the law of mass action in which the drug binds reversibly to the protein at a single site. After attachment to a receptor site, a drug may either initiate a response or prevent a response from occurring.
A chelator sequester of similar agent that interacts directly with the drug being antagonized to remove it or prevent it from binding its receptor. This means the drug is designed to specifically target and react with that specific biomolecule. Theories for relationship between drug receptor interaction. 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. Receptor theory is the application of receptor models to explain drug behavior. Ionic interactions are more reversible, compared to its covalent counterpart.
Whereas various drug drug interactions have been described for clopidogrel and ticagrelor, prasugrel seems to have a lower potential for drug drug interactions. However, some drug effects are non receptor mediated and are caused by the particular physical or chemical properties of the drug molecule. The pharmacodynamic interactions of drug on drug can be divided into three broad groups. Drug receptor interactions the ability of a drug to produce an effect results from specific chemical interactions between the drug and specific sites lipoprotein receptors, enzymes, biomembranes, nucleic acids or small molecules. Receptor is a macromolecule in the membrane or inside the cell that specifically chemically bind a ligand drug. A chemical antagonist does not depend on interaction with the agonists receptor although such interaction may occur. It is shown that conformational entropy may be used for prediction of the drug affinity to a certain receptor. Drug receptor interactions may be modified by changes in receptor sensitivity, this being influenced by complex regulatory and homeostatic factors. In general, concomitant administration of strong cyp3a4 inhibitors or inducers should be avoided in patients treated with p2y 12 receptor. Drugreceptor interactions clinical pharmacology msd. Ccr5 antagonist drug interactions drugdrug interactions. Functional groups, drugreceptor interactions and drug design. A drug molecule is considerably smaller in size than a receptor.
Antagonists are drugs that bind to receptors without activating them, and consequently prevent the binding of other agonists. Interactions between drugs can be classified as pharmacokinetic or pharmacodynamic. Most of the drugs binding receptors resemble the agonists but they cannot activate the receptors, and also prevent agonist binding. Receptor types, mechanism, receptor pharmacology, drug receptor interactions, theories of receptor pharmacology, spare receptors and new concepts like biased a slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. This type of bonding is the strongest form of bond that can be formed between a ligand and a receptor. The interest in conformational entropy started from developing new drugs.
Introduction cannabis or marijuana is the most commonly used illegal substance in the world and approximately four percent of the worlds population has used cannabis at least once in the past year leggett. Along with antidiabetic medicines they may take drugs such as otc medicines, prescription medicines, treat other illnesses which may interact with them. Classification of drugs based on drugreceptor interactions. Conformational entropy in drugreceptor interactions. Introduction to structurebased drug design a practical guide tara phillips. Pharmacology, psychoactive agents and drug interactions ureh nena lekwauwa, m.
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