drug receptors intercaction and drug antagonism : dr rahul kunkulol's power point preparations
DESCRIPTION
TRANSCRIPT
![Page 1: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/1.jpg)
RECEPTORS AND RECEPTOR
SUPERFAMILIES
Dr.Rahul Kunkulol Asso. Professor dept. of Pharmacology
RMC,LONI
Receptor
DRUG
![Page 2: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/2.jpg)
INTRODUCTION
“Corpora non agunt nisi fixate”.P. Ehrlich (1908)
Paul Ehrlich described drug-receptor binding:(“Agents do not act unless they are bound”)
Receptor
DRUG
![Page 3: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/3.jpg)
DrugsDrugs can be defined as agents that uniquely interact with specific target molecules in the body, thereby producing a biological effect.
![Page 4: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/4.jpg)
Drugs can be
stimulatory or
inhibitory
![Page 5: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/5.jpg)
Drugs
Drugs interact with biological systems in ways that mimic, resemble or otherwise affect the natural chemicals of the body.
• - or -Drugs can produce effects by virtue of :• Acidic or basic properties (e.g. Antacids,
protamine)• Surfactant properties (amphotericin)• Ability to denature proteins (astringents)• Osmotic properties (laxatives, diuretics)• Physicochemical interactions with membrane
lipids (general and local anesthetics).
![Page 6: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/6.jpg)
DRUG SPECIFICITY Specificity is reciprocal: Individual classes of drug bind only to certain targets, and individual targets recognized only certain classes of drug.No drugs are completely specific in their action. In many cases increasing the dose of a drug will cause it affect target other than the principle one, and this can lead to side effects. E.g. TCA
![Page 7: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/7.jpg)
Targets for drug action
•Receptor
•Ion channels
•Enzymes
•Carrier molecules
Four kinds of
regulatory protein involved
as primary
drug targets.
![Page 8: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/8.jpg)
Targets for drug action
![Page 9: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/9.jpg)
ION CHANNELSLigand gated ion channels –incorporate a receptor and open or close only when the receptor is occupied by an agonist. Ex.- Local anesthetics (direct) Voltage gated ion channels-drugs binds on accessory sites on the channel protein and affect channel gating.Ex.- dihydropyridines (indirect)
![Page 10: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/10.jpg)
ENZYMESMany drugs target enzymes. Often the drug molecule is a substrate analogue that act as a competitive inhibitor of the enzyme ,either reversibly or irreversibly. Examples:- Enzymes Inhibitors Acetylcholinesterase Neostigmine Cyclooxygenase Aspirin
![Page 11: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/11.jpg)
CARRIER MOLECULE The transport across cell
membranes of ions and organic molecules generally requires a carrier protein . Ex. 1.Transport of glucose,a.a. into the cell. 2.Transport of ions, organic molecule into the tubule.
![Page 12: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/12.jpg)
RECEPTOR Receptor are the sensing elements in the
system of chemical communications that coordinates the function of all the different cells in the body.
Chemical messengers : Hormones
Drugs Transmitters Other mediators
![Page 13: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/13.jpg)
Drug and receptorDrugs, as well as hormones, neurotransmitter, autacoids and toxins can make possible the transfer of information to cells by interaction with specific receptive molecules called “receptors”.
Receptor
DRUG
![Page 14: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/14.jpg)
DRUG RECEPTOR INTERACTION
Receptor mediated response
Binding Activation
Occupation of receptor by a drug molecule may or may not result in activation of the receptor.
![Page 15: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/15.jpg)
Drug-Receptor Interactions
Drug-receptor interactions serve as signals to trigger a cascade of events. This cascade or signaling pathway, is a collection of many cellular responses which serve to amplify the signal and produce a final effect.
Effectors are thus the molecules that translate the drug-receptor interaction into changes in cellular activity.
+ EFFECT
DRUG DRUG + RECEPTOR DRUG + RECEPTOR EFFECTOR EFFECTOR INTERACTION COMPLEX SYSTEM
STIMULUS BINDING ACTIVATION TRANSDUCTION AMPLIFICATION RESPONSE
SIGNALLING PATHWAY
![Page 16: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/16.jpg)
Classification of Receptors
IUPHAR (International Union of Pharmacological Science)Pharmacological
Mediator (i.e. Insulin, Norepinephrine, estrogen)
Biochemical and BiophysicalSecond messenger system (i,.e. cAMP,
PLC, PLA) Molecular or Structural
Subunit composition (i.e. 5HT1A )Anatomical
Tissue (i.e muscle vs ganglionic nAChRs)
Cellular (i.e. Membrane bound vs Intracellular)
![Page 17: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/17.jpg)
RECEPTOR SUPERFAMILIES
LIGAND- GATED ION CHANNELS G-PROTEIN COUPLED RECEPTORS KINASE LINKED RECEPTORS NUCLEAR RECEPTORS
![Page 18: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/18.jpg)
Type- Ionotropic receptors
Location-cell membrane
Effector-ion channel
Coupling-direct Examples-Fast neurotransmitters :
Nicotinic Ach Glutamate GABAA,
LIGAND GATED ION CHANNELS
![Page 19: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/19.jpg)
LIGAND GATED ION CHANNELS
![Page 20: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/20.jpg)
GATING MECHANISM
Neurotransmitter
Post synaptic membrane inotropic receptor (LGIC)
Increased permeability of ions
Depolarization
Action potential
![Page 21: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/21.jpg)
STRUCTURE OF ACH NICOTINIC RECEPTOR
![Page 22: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/22.jpg)
GABAA RECEPTOR
![Page 23: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/23.jpg)
GABAA RECEPTOR
![Page 24: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/24.jpg)
GABA
metabolites
Succinic Semialdehyde
GT: GABA transaminase SSD: Succinic semialdehyde dehydrogenase
GT
SSD
Cl-
![Page 25: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/25.jpg)
G – PROTEIN COUPLED RECEPTORS
Type: Metabotropic Location: Cell membrane Coupling: G-protein
Exampels- Muscarinic, Adrenergic, Opioid, Dopamine, 5HT,Peptides,Purines
![Page 26: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/26.jpg)
![Page 27: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/27.jpg)
SIGNAL TRANSDUCTION
![Page 28: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/28.jpg)
CLASSES OF G-PROTEINS Gs Gi Gq Go
Amplification………..?
![Page 29: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/29.jpg)
![Page 30: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/30.jpg)
Receptor Signaling Pathways
Adenylate Cyclase (AC)
Guadenylyl Cyclase (GC)
Phospholipase C (PLC)
Phospholipase A (PLA2)
Nitric oxide Synthase
Ions
cAMP cGMP DAG and IP3 Arachidonic acid NO and CO Na+, Ca2+, K+, Cl-
SECOND MESSENGER
EFFECTOR
![Page 31: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/31.jpg)
Adenylate Cyclase ATP cAMP Activation of PK
Phosphorylation
of cell proteins 5AMP Enzymes involved in energy metabolism, cell division, cell differentiation, ion channels, and contractile proteins in smooth muscles
![Page 32: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/32.jpg)
REGULATION OF ENERGY BY CAMP
![Page 33: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/33.jpg)
PHOSPHOLIPASE C
![Page 34: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/34.jpg)
ION CHANNELLS AS TARGET FOR G- PROTEINS GPCR controls ion channels directly
by mechanism that they do not involve second messengers like cAMP or IP3.
Either alpha or beta and gamma subunits of G protein acts as second messenger
Ex-m ACH receptor enhances K+ permeability
![Page 35: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/35.jpg)
KINASE LINKED RECEPTORS
Mediate the actions of wide variety of proteins mediators including growth factors, cytokines & hormones such as insulin.
Receptor for various hormones (insulin) & growth factor incorporate tyrosine kinase activity in their intracellular domain.
Cytokine receptors have intracellular domain that activates cytosolic kinases when the receptor is occupied.
![Page 36: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/36.jpg)
SIGNAL TRANSDUCTION
Receptor Ligand binding
Dimerisation of receptor
Autophosporylation of tyrosine residue
Binding of intracellular proteins
Gene transcription
![Page 37: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/37.jpg)
![Page 38: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/38.jpg)
NUCLEAR RECEPTORS Nuclear receptors regulate gene
transcription. Nuclear receptor-a misnomer as
they are located in the cytosol and migrate to nucleus when ligand is present.
Examples: Steroid hormones, thyroid hormones retinoic acid and vit. D.
![Page 39: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/39.jpg)
SteroidReceptor
Confomational change
Dimer
Move to nucleus and bind to hormone – responsive elements
Increase RNA Polymerase activity
Production of specific m RNA
![Page 40: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/40.jpg)
NUCLEAR RECEPTORS
![Page 41: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/41.jpg)
RECEPTOR SUPERFAMILIES
![Page 42: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/42.jpg)
RECEPTOR SUPERFAMILIES
![Page 43: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/43.jpg)
DESENSITISATION & TACHYPHYLAXIS
Definition: TACHYPHYLAXIS The effect of a drug gradually diminishes
when it is given continuously or repeatedly, which often develops in the course of minutes.
Tolerance is conventionally used to describe a more gradual decrease in responsiveness to a drug, taking days or weeks to develop.
The distinction is not sharp. Refractoriness is used to indicate loss of
therapeutic efficacy. Drug resistance is used to indicate loss of
effectiveness of antimicrobial or anti tumor drugs.
![Page 44: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/44.jpg)
MECHANISMS Loss or change in receptors Exhaustion of mediators metabolic degradation Physiological adaptation Active extrusion of drug from cell
![Page 45: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/45.jpg)
Drug-Receptor InteractionsTheory and assumptions of drug-receptor
interactions. Drug Receptor interaction follows simple Law
mass-action relationships,
The magnitude of the response is proportional to the fraction of total receptor sites occupied by drug molecules.
Combination or binding to receptor causes some event which leads to a response.
Response to a drug is graded or dose-dependent.
![Page 46: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/46.jpg)
Dose response curve…...
![Page 47: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/47.jpg)
Agonism and Antagonism
![Page 48: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/48.jpg)
Cont..AGONIST: Binding + ActivationAgonists facilitate receptor response
ANTAGONIST: If a drug binds to the receptor without causing activation and thereby prevents the agonists from binding, is termed as Antagonist.
Tendency of a drug to bind the receptor is governed by its affinity, where as tendency of it, ones bound, to activate the receptor is denoted by its efficacy.
PARTIAL AGONISTS: Drugs with intermediate levels of efficacy, such that even if 100% of receptors are occupied the tissue response is sub maximal.
![Page 49: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/49.jpg)
PARTIAL & FULL AGONIST
![Page 50: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/50.jpg)
Partial Agonists Full agonists
max response Full response @
~20% occupancy Partial agonists
sub maximal response
100% occupancy ~40% response
![Page 51: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/51.jpg)
Comparison of Affinity & Efficacy of Ligands
Ligand Affinity Efficacy
Agonist ++++ ++++
Antagonist ++++ -
Partial agonist ++++ ++
![Page 52: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/52.jpg)
TWO STATE MODEL The receptor shows the two
conformational stage resting (R) and activated (R*) which exist in equilibrium.
R R* Normally when no ligand is present,
the equilibrium lies far to the left.
![Page 53: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/53.jpg)
In the presence of ligand (A) equilibrium will depend on
equilibrium constant i.e. /. For pure antagonist it is zero. For agonist it is a finite value. For drug X / is small – partial
agonist For drug Y / is large – agonist Therefore constant / is measure of
efficacy
![Page 54: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/54.jpg)
R+D=
![Page 55: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/55.jpg)
DRUG ANTAGONISM The effect of one drug is diminished or
completely abolished in the presence of another.
CLASSIFICATION Chemical antagonism Pharmacokinetic antagonism Antagonism by receptor block Noncompetitive antagonism, i.e. block of
receptor – effector linkage Physiological antagonism
![Page 56: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/56.jpg)
Cont…
CHEMICAL ANTAGONISM
Two substances combine in solution and effect of active drug is lost, e.g. Dimercaprol bind to heavy metals
PHARMACOKINETIC ANTAGONISM
In this antagonist effectively reduces the concentration of the active drug at its site of action. This can happen various ways by increased metabolic degradation, decreased absorption or increased excretion.
![Page 57: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/57.jpg)
REVERSIBLE COMPETITIVE ANTAGONISM
• Antagonist binds receptor but does not activates it.
• Incr’d [agonist] restores tissue response to agonist
• Antagonism “surmountable
• In the presence of antagonist, the agonist log concentration effect curve is sifted to the right without change in slope or maximum.
![Page 58: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/58.jpg)
Antagonism-Competitive
![Page 59: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/59.jpg)
IRREVERSIBLE COMPETITIVE ANTAGONISM
• In this antagonist dissociates very slowly or not at all resulting in no change in antagonist occupancy when agonist is applied. Covalently bind receptors
Irreversible, insurmountable antagonism
↓ number of available receptors -- ↓ agonist max response
![Page 60: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/60.jpg)
IRREVERSIBLE COMPETITIVE ANTAGONISM
![Page 61: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/61.jpg)
NONCOMPETITIVE ANTAGONISM Antagonists blocks at some points chain of
events that lead to production of response by agonist.
Effect will be slope and maximum of the agonist log concentration response curve.
PHYSIOLOGICAL ANTAGONISM In this there is interaction of two drugs
whose opposing action in the body tend to cancel each other example – Histamine and Omeprazole on parietal cell of gastric mucosa.
![Page 62: Drug Receptors intercaction and Drug antagonism : Dr Rahul Kunkulol's Power point preparations](https://reader033.vdocuments.mx/reader033/viewer/2022061102/53f6e1c98d7f72fb508b456f/html5/thumbnails/62.jpg)