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A PRESENTATION ON
DRUG ANTAGONISM
Presented by-
Vipul Agarwal
BBAU, Lucknow
1
DRUG ANTAGONISM
One drug or inhibits action of another drug
i.e
Effect of A + B < Effect of drug A +
Effect of drug B
Types of Antagonism
a) Physical antagonism
b) Chemical antagonism
c) Physiological/functional
antagonism
d) Pharmacologica...
A) Physical Antagonism
 Based on physical property of drugs,
e.g. charcoal (adsorb alkaloid) in alkaloidal
poisoning
B) Chemical Antagonism
 A type of antagonism where a drug
counters the effect of another by simple
chemical reaction / ne...
C) Functional Antagonism
(Physiological Antagonism)
Opposite effects of two drugs
on same function
 Two drugs act on two ...
D) Pharmacological Antagonism
Competitive Non-competitive
Equilibrium Non-equilibrium
(Reversible) (Irreversible)
Antagonist Receptor
Antagonist-Receptor
Complex
DENIED!
Competitive Antagonism
1.Same receptor by forming Weak
bonds
2.Maximal response is concentration
dependent
3.The effect of antagonist can be
over...
Cont……
e.g. Atropine and Acetylcholine at Muscarinic -R
Naloxone and Morphine at opioid-R
COMPETITIVE Irreversible
ANTAGONISM
1. Have affinity for the same receptor sites
and bind in an irreversible manner by
cov...
Agonist Receptor
Antagonist
‘Inhibited’-Receptor
DENIED!
NON COMPETITIVE
ANTAGONISM
i. Binds to site other than the agonist
site
ii. Prevent the receptor activation by
the agonist
e.g. Flumazenil by binding...
Cont……
REFERENCES
 Sharma – Priciples of Pharmacology,
2nd Edition
 K.D Tripathi – Essentials of Medical
Pharmacology, 7th edit...
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Drug Antagonism

Drug Antagonism

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Drug Antagonism

  1. 1. A PRESENTATION ON DRUG ANTAGONISM Presented by- Vipul Agarwal BBAU, Lucknow 1
  2. 2. DRUG ANTAGONISM One drug or inhibits action of another drug i.e Effect of A + B < Effect of drug A + Effect of drug B
  3. 3. Types of Antagonism a) Physical antagonism b) Chemical antagonism c) Physiological/functional antagonism d) Pharmacological antagonism
  4. 4. A) Physical Antagonism  Based on physical property of drugs, e.g. charcoal (adsorb alkaloid) in alkaloidal poisoning
  5. 5. B) Chemical Antagonism  A type of antagonism where a drug counters the effect of another by simple chemical reaction / neutralization(not binding to the receptor) e.g. Calcium sodium edetate form insoluble complexes with arsenic / lead
  6. 6. C) Functional Antagonism (Physiological Antagonism) Opposite effects of two drugs on same function  Two drugs act on two diff. types of receptors & antagonize action of each other e.g. Glucagon and insulin on blood sugar level
  7. 7. D) Pharmacological Antagonism Competitive Non-competitive Equilibrium Non-equilibrium (Reversible) (Irreversible)
  8. 8. Antagonist Receptor Antagonist-Receptor Complex DENIED! Competitive Antagonism
  9. 9. 1.Same receptor by forming Weak bonds 2.Maximal response is concentration dependent 3.The effect of antagonist can be overcome by increasing the concentration of agonist 4. Parallel rightward shift of DRC COMPETITIVE Reversible ANTAGONISM
  10. 10. Cont…… e.g. Atropine and Acetylcholine at Muscarinic -R Naloxone and Morphine at opioid-R
  11. 11. COMPETITIVE Irreversible ANTAGONISM 1. Have affinity for the same receptor sites and bind in an irreversible manner by covalent bond 2. Effects cannot be overcome even by increasing the concentration of the agonist 3. LDR curves of agonist would show reduced efficacy but altered potency e.g. Dibenamine and NE at α1 adrenoceptors
  12. 12. Agonist Receptor Antagonist ‘Inhibited’-Receptor DENIED! NON COMPETITIVE ANTAGONISM
  13. 13. i. Binds to site other than the agonist site ii. Prevent the receptor activation by the agonist e.g. Flumazenil by binding to BZD site antagonises the effects of BZD by preventing the binding of GABA to GABAA receptor Cont……
  14. 14. Cont……
  15. 15. REFERENCES  Sharma – Priciples of Pharmacology, 2nd Edition  K.D Tripathi – Essentials of Medical Pharmacology, 7th edition  R.S Satoskar – Pharmacology and Pharmacotherapeutics, 18th Edition  www.google.com

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