1. By Amany Helmy Hasanin Assistant Professor of Clinical Pharmacology
Pharmacodynamic-2 By
Amany Helmy Hasanin
Assistant Professor of Clinical Pharmacology

2. Student Activity Intrinsic activity is, a drug’s ability to elicit:
a) Strong receptor binding
b) Weak receptor binding c) Response
d) Excretion
e) Distribution

3. Agonists
A drug (chemical) that is able to alter the conformation of a receptor in such a way that it elicits a response in the system

4. Agonists Types
Full Agonist
Partial Agonist
Inverse Agonist

5. Full Agonist Agonist binds to receptors to activate them
Agonist possess affinity and efficacy

6. Partial Agonist (Agonist-Antagonist) In presence of agonist
works as antagonist

7. Inverse Agonist
Agonist
Antagonist

8. Graded dose response curve
Emax
100%
Response
50%
ED50
Dose (Log)
Graded dose response curve

9. Graded (quantitative) dose response curve
Drug A
Drug B
Emax
100%
Response
50%
ED50
ED50
Dose (Log)

10. Emax
The maximal effect produced by the drug (= the maximum value of the dose-response curve)
Efficacy

11. The dose that produces 50% of the maximum therapeutic effect
Effective dose fifty ED50
The dose that produces 50% of the maximum therapeutic effect

12. Slope The middle portion of the curve
(it reflects the effect of the drug produced by one unit of the dose)

13. Efficacy (Emax) Potency (ED50 and slope)
Data we can get from graded dose response curve
Efficacy (Emax)
Potency (ED50 and slope)

14. Graded (quantitative) dose response curve
Drug A
Drug B
Emax
Response
50%
ED50
ED50
Dose (Log)

15. Graded dose response curve
Drug A
100%
Emax
Drug B
100%
Emax
Response
50%
50%
ED50
ED50
Dose (Log)

16. Antagonist binds to receptors prevents Affinity without efficacy
Agonist to bind
Affinity without efficacy

17. Graded dose response curve
100%
Response
50%
ED50
Dose (Log)
Graded dose response curve

18. Compete with agonists for the same recognition site of the receptors
Types of Receptor Antagonists
Competitive
Compete with agonists for the same recognition site of the receptors

19. competitive antagonist
Graded dose response curve
Agonist+
competitive antagonist
Agonist alone
Emax
Response
50%
ED50
ED50
Dose (Log)

20. Types of Receptor Antagonists (Cont.)
Noncompetitive
Prevent binding of the agonist or
prevent activation of the receptor by the agonist

21. Non-competitive antagonist
Graded dose response curve
Agonist alone
Emax
Agonist+
increasing doses of
Non-competitive antagonist
Response
Dose (Log)

22. Is there any clinical application competitive and non competitive antagonist

23. Are there other types of antagonists
The action of a ligand can be reversed by non-receptor antagonists

24. Antagonist interact chemically with the agonist away from receptor
Chemical antagonist
Antagonist interact chemically with the agonist away from receptor
Negative charges on heparin are neutralized by positive charges on protamine sulfate (heparin antidote)

25. Physiological antagonist
Antagonist by acting on different receptors induce the opposite actions of the agonist

26. Histamine
H receptors
Epinephrine

27. Non-receptor Mediated Mechanisms
Drugs Acting on Enzymes Drugs Acting on Plasmatic Membranes Drugs Acting on the Genetic Apparatus Drugs Acting on Subcellular Structures Drugs Acting by Physical Means Drugs Acting by Chemical Action
May affect permeability, carrier systems, transport processes or enzyme systems in the plasmatic membrane
antifungal drugs increase permeability of fungal plasmatic membrane
Drus acting on genetic apparatus
Antibiotics (e.g. aminoglycosides, chloramphenicol & tetracyclines) inhibit bacterial protein synthesis
Anticancer Drugs affect DNA synthesis or function
Drugs acting on subcellular structures
Mitochondria: salicylates uncouple oxidative phosphorylation
Microtubules: Antimitotic agents

28. Drugs Acting on Enzymes

29. Drugs Acting on Plasmatic Membranes
Affect permeability, carrier systems, transport processes or enzyme systems in the plasmatic membrane

30. Drugs Acting on the Genetic Apparatus

31. Drugs Acting on Subcellular Structures
Mitochondria
Microtubules

32. Drugs Acting by Physical Means
Demulcents (soothing):
a substance that relieves irritation of the mucous membranes by forming a protective film, lozenges

33. Drugs Acting by Physical Means (Cont.)
Adsorbents: a substance that adsorbs another
charcoal adsorbs gases and toxins in intestine

34. Drugs Acting by Physical Means (Cont.)
Lubricants:
liquid paraffin is used in constipation
Osmosis:
osmotic diuretics
e.g. Mannitol

35. Drugs Acting by Chemical Action
Antacids
neutralize HCL in peptic ulcer
Citrates
interact with calcium to inhibit blood coagulation

36. Drugs Acting by Chemical Action (Cont.)
Protamine sulfate
neutralizes heparin by its positive charges
Heparin
Protamine

37. Drugs Acting by Chemical Action (Cont.)
Chelation
Desferroxamin (multiple blood transfusion)

38. At the end I am expecting from you to be able to
Compare efficacy and potency of two drugs
Identify and compare between different types of agonist
Specify and compare between different types of antagonist