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IN THE NAME OF GOD

Explore the principles of pharmacodynamics, the mechanism of drug actions, and the drug-receptor interaction in this comprehensive study of pharmacology. Learn about drug classification, dose-response relationships, and the scientific basis for drug selection and use.

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IN THE NAME OF GOD

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  1. IN THE NAME OF GOD

  2. Introduction What is pharmacology Principles of pharmacodynamics Mechanism of Drug Actions Drug-Receptor Interaction Classification of Drugs Dose-Response Relationships

  3. What is Pharmacology? Pharmakon= a drug or poison Logos= discourseor study The science that deals with: • The fate of drugs in the body Pharmacokinetics • The actions of drugs on the body Pharmacodynamics

  4. Pharmacy The science of preparation of drugs Pharmacotherapeutics The treatment of diseases by drugs

  5. Textbooks • Basic & Clinical Pharmacology, 2004 Bertram G. Katzung • Goodman and Gilman’s The pharmacological basis of therapeutics, 2001 (J.G. Hardman and L.E. Limbard, eds.) New York: McGraw-Hill • (first published in 1941)

  6. Principles of Pharmacodynamics

  7. Pharmacodynamics Mechanisms of drug action & the relationship between drug concentration and effect Why to study Pharmacodynamics? Scientific basis for the selection & use of drugs

  8. Mechanism of Drug Action Basic Concept Interaction of a drug with its target tissue involves specific binding sites Receptor A macromolecular component of the cell to which the drug binds and leads to an effect on the cell Nonspecific binding site A biological component to which the drug binds but does not lead to any effect

  9. Nature of Drug Receptors Proteins Transmembrane proteins Receptorsfor neurotransmitters Transport proteins Na+/K+ ATPase digitalis glycosides Ion channels benzodiazepines Structural proteins Tubulin colchicine Enzymes Cycloxygenase acetylsalicylic acid ACE Captopril

  10. Non-protein drug receptors • Lipids Anesthetics Nystatin, Amphotericin • Nucleotides Antineoplastic drugs Cyclophosphamide

  11. Other Sites of Drug Action • Water Osmotic Diuretics & Laxatives • Ions Antacids Changing urine pH Chelators Dimercaprol Hg+2 , As+2 Penicillamine Cu+2 EDTA Pb2

  12. Drug-Receptor Interaction Chemical forces or bonds Covalent Strong & Usually irreversible Electrostatic strong linkages between charged ionic molecules weak hydrogen bonds dipole interactions (van der Waals forces) Hydrophobic weak ; highly lipid soluble drugs

  13. Drug-Receptor Interaction

  14. Drug-Receptor Interaction K1 R + D R-D Effect Affinity The tendency of a drug to combine with its receptor Kd The concentration of drug that binds to 50% of the receptors Affinity= the reciprocal of the Kd K2

  15. Drug-Receptor Interaction K1 R + D R-D Effect Intrinsic Activity The ability of a drug to initiate a cellular effect K2

  16. Receptor-Effector Coupling • Receptor conformational change • Coupling Efficiency

  17. Drug-Receptor Binding

  18. Concentration-Effect Relationship

  19. Classification of drugs Agonist Full agonist Partial agonist Antagonist Competitive antagonist Non-competitive antagonist

  20. Other Drug Antagonism Chemical antagonists Heparin & protamine Physiologic antagonism Glucocorticoids & Insulin

  21. Dose-Response Relationship Graded dose-response Quantal dose-response

  22. Graded Dose-Response Relationship

  23. Sigmoidal D-R Curve

  24. Graded Dose-Response Relations Potency Efficacy

  25. Relative potency

  26. Relative Efficacy

  27. Agonists with different potency

  28. Agonists with different efficacy

  29. Competitive Antagonism

  30. D-R Curve for Competitive Antagonists

  31. Non-Competitive Antagonism

  32. Quantal D-R Curve

  33. Quantal D-R Curve

  34. Quantal D-R Curve

  35. Quantal-Dose Response • Median Effective Dose (ED50) • Median Toxic Dose (TD50) • Median Lethal Dose (LD50) • Therapeutic index LD50/ED50 or TD50/ED50

  36. Signaling Mechanisms& Drug Action

  37. Transmembrane Signaling • Intracellular receptors • Enzyme-linked receptors • Ligand-gated ion channels • G-protein-coupled receptors

  38. Intracellular Receptors Steroid Receptor Superfamily Glucocorticoids Mineralocorticoids Sex hormones Vitamin D Thyroid hormone Retinoic Acid

  39. Therapeutically important consequences • Slow onset of action • Persistence of effect following withdrawal of the drug

  40. Enzyme-Linked Receptors Receptor Tyrosine Kinases Insulin Epidermal growth factor (EGF) Platelet-derived growth factor (PDGF)

  41. Receptor Tyrosine Kinases

  42. Enzyme-Linked Receptors Receptor Guanylyl Cyclase Atrial natriuretic factor (ANF) cGMP (Natriuresis; Vasodilation) Receptor Serine Kinase Transforming growth factor-beta (TGF-b) Cytokine Receptors

  43. Cytokine Receptor

  44. Ligand-gated Ion Channels Acetylcholine nicotinic receptors Neuromuscular blocking drugs (tubucurarine) Ganglion blockers (Mecamylamine) GABAA Benzodiazepines (sedative-hypnotic) Glutamate Topiramate (anticonvulsant)

  45. Ligand-gated Ion Channels

  46. G Protein-Coupled Receptors

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