Pharmacodynamics

Pharmacodynamics is the study of the biochemical and physiological effects of drugs and their mechanisms of action. Pharmacodynamics is often referred to as “what the drug does to the body”.
In order to exert their effects, drugs usually interact in a structurally specific way with a protein receptor or act on physiological processes within the body. This activates a secondary messenger system that produces a physiological effect. Drugs do not create new action but they can only modify (alter) the functions of cells or tissues in body. The drug–receptor complex initiates alterations in biochemical and/or molecular activity of a cell by a process called signal transduction.

1. Prof. Amol B. Deore Department of Pharmacology MVP’s Institute of Pharmaceutical Sciences, Nashik

2. Introduction

3. Principles of drug action

4. Stimulation

5. Depression

6. Irritation

7. Replacement

8. Chemical action

9. Cytotoxic action Some drugs act by selective cytotoxic action on invading parasites or cancer cells without affecting the host cells. They are used for treatment of infectious diseases and cancer. e.g ., penicillin, chloroquine, remdesivir, cyclophosphamide.

10. MECHANISMS OF DRUG ACTION

11. Through receptors: Drugs may act by interacting with specific receptors in the body.

12. Through enzymes and pumps:

13. Through ion channels:

14. By physical action:

15. By chemical interaction:

16. By altering metabolic processes:

17. Drug and receptor concepts

18. Receptor

19. Potency

20. Affinity

21. Efficacy

22. Agonist

23. Agonist Receptor Response

24. Antagonist

25. Antagonist Receptor No Response e.g., atropine is antagonist of cholinergic receptors For example

26. Partial agonist

27. Drug Receptor Interaction

28. lock and key

29. Receptor types

30. Binding forces

31. Drug Antagonism

32. Competitive Antagonism

33. Competitive Antagonism

34. Ex. Competitive antagonist and their receptors Agonist Competitive Antagonist Receptors Acetylcholine Adrenaline Histamine Morphine Atropine Phentolamine Cetrizine Naloxone Cholinergic receptors Adrenergic receptors Histamine receptors Opioid receptors

35. Non-Competitive Antagonism

36. Ex. Non-competitive antagonist and their receptors Agonist Non-competitive Antagonist Receptors Nor-Adrenaline Acetylcholine Diazepam Organophosphorous compounds Phenoxybenzamine Bungarotoxin Bicuculine Atropine sulphate alpha receptors Cholinergic receptors GABA receptors Cholinergic receptors

37. Physiological Antagonism

38. Chemical Antagonism

39. Therapeutic Index

40. The therapeutic index formula Therapeutic index (TI) = Median Toxic Dose (TD50) _ Median Effective Dose (ED50)

41. Therapeutic window

42. Therapeutic Index

43. Prof. Amol Deore